An Update on Airway Management [1 ed.] 9789811432385, 9789811432378

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Recent Advances in Anesthesiology (Volume 3) (An Update on Airway Management) Edited by Eugenio Daniel Martinez-Hurtado Department of Anesthesiology and Intensive Care, University Hospital Infanta Leonor, Madrid, Spain

& María Luisa Mariscal Flores Department of Anesthesiology and Intensive Care, Hospital Universitario de Getafe, Madrid, Spain

 

5HFHQW$GYDQFHVLQ$QHVWKHVLRORJ\ Volume # 3 An Update on Airway Management Editors: Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores ISBN (Online): 2589-9392 ISBN (Print): 2589-9384 ISBN (Online): 978-981-14-3238-5 ISBN (Print): 978-981-14-3237-8 © 2020, Bentham Books imprint. Published by Bentham Science Publishers Pte. Ltd. Singapore. All Rights Reserved.

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CONTENTS PREFACE I .............................................................................................................................................. i PREFACE II .......... ................................................................................................................................... ii PREFACE III .......... .................................................................................................................................. iii INTRODUCTION ................................................................................................................................... iv LIST OF CONTRIBUTORS .................................................................................................................. v CHAPTER 1 AN UPDATE ON DIAGNOSTIC ACCURACY (CT, X-RAY) FOR AIRWAY MANAGEMENT ..................................................................................................................................... Montiel Redondo Castillo and Eduardo González Constán BACKGROUND ............................................................................................................................. CONVENTIONAL RADIOLOGY ............................................................................................... COMPUTED TOMOGRAPHY .................................................................................................... ULTRASONOGRAPHY ................................................................................................................ CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENT ............................................................................................................. REFERENCES ............................................................................................................................... CHAPTER 2 AN UPDATE ON ULTRASONOGRAPHY AS A TOOL FOR AIRWAY MANAGEMENT ..................................................................................................................................... Miguel Ángel Fernández Vaquero, Maria Aliaño Piña, Maria Aymerich De Franceschi and Monir Kabiri Sacramento INTRODUCTION .......................................................................................................................... BASIC CONCEPTS ....................................................................................................................... Anatomy of the Airway .......................................................................................................... Systematization of the Echographic Examination .................................................................. A. Transversal Cut ........................................................................................................ B. Longitudinal Cut ....................................................................................................... Parameters that could Define a Difficult Airway ................................................................... Location of the Cricothyroid Membrane ................................................................................ Confirmation of Oesophageal vs. Endotracheal Intubation .................................................... Directly .......................................................................................................................... Indirectly ....................................................................................................................... Percutaneous Dilatational Tracheostomy ............................................................................... ULTRASOUND VS. ANATOMIC REFERENCES .................................................................... ULTRASOUND VS. FIBEROPTIC BRONCHOSCOPY .......................................................... CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENT ............................................................................................................. REFERENCES ............................................................................................................................... CHAPTER 3 AN UPDATE ON PREOXYGENATION, APNEIC OXYGENATION, AND PREVENTION OF DISTORTION DURING AIRWAY MANAGEMENT ..................................... Paloma Muñoz Saldaña, Norma Aracil Escoda, Elena Sáez Ruiz, Ana Tirado Errazquin and Flores María Rey Tabasco INTRODUCTION .......................................................................................................................... PATHOPHYSIOLOGY OF OXYGENATION ........................................................................... PREOXYGENATION ....................................................................................................................

1 1 2 6 8 11 11 12 12 12 15 15 16 17 18 18 20 21 23 25 25 27 28 28 28 29 29 29 29 29 31 31 32 32

SECONDARY EFFECTS OF PREOXYGENATION ................................................................ APNEIC OXYGENATION ........................................................................................................... PREOXYGENATION BEFORE EXTUBATION ...................................................................... CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ...............................................................................................................................

35 36 38 38 38 38 38 39

CHAPTER 4 SUPRAGLOTTIC AIRWAY DEVICES UPDATE ................................................... María Luisa Mariscal Flores, Rocío Castellanos González, María Jesús Jiménez Garcia, Sonia Martín Ventura and Claudia Palacios Muñoz INTRODUCTION .......................................................................................................................... CLASSIFICATION OF SADS ...................................................................................................... LARYNGEAL MASKS AIRWAY (LMA) .................................................................................. Types ....................................................................................................................................... Classic Laryngeal Mask (cLMA) .................................................................................. Flexible Laryngeal Mask (fLMA) .................................................................................. Laryngeal Mask Proseal (PLMA) ................................................................................. Mask LMA (MLF or ILMA) Intubation Laryngeal Fastrach ........................................ Disposable Laryngeal Masks ........................................................................................ LMA Protector™ .......................................................................................................... LMA Indications ..................................................................................................................... Basic Indications ........................................................................................................... Indications of Rescue .................................................................................................... Advanced Instructions ................................................................................................... Complications ............................................................................................................... Risk Factors for Airway Management with SAD .......................................................... OTHER SUPRAGLOTTIC AIRWAY DEVICES ...................................................................... Combitube ............................................................................................................................... Easytube .................................................................................................................................. Laryngeal Tube ....................................................................................................................... CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ...............................................................................................................................

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CHAPTER 5 OPTIC AIRWAY DEVICES UPDATE ....................................................................... Eugenio Daniel Martinez-Hurtado, Miriam Sanchez-Merchante, Pablo Renedo Corcóstegui, Manuel Granell Gil and Guillermo Navarro INTRODUCTION .......................................................................................................................... CONCEPT ....................................................................................................................................... FEATURES ..................................................................................................................................... INDICATIONS ............................................................................................................................... LIMITATIONS ............................................................................................................................... COMPLICATIONS ........................................................................................................................ CLASSIFICATION ........................................................................................................................ Videolaryngoscopes with Rigid Blade .................................................................................... VL with 'Standard' Rigid Blade ..................................................................................... VL with Angled Rigid Blade .......................................................................................... Videolaryngoscopes with Blade with Channel to Guide the Endotracheal Tube ...................

56

40 41 42 42 42 43 43 43 43 45 46 46 47 47 48 48 49 49 51 51 52 53 53 53 53

56 57 57 59 60 61 62 62 62 63 63

Videolaryngoscopes that Allow the Oxygenation during Intubation Manoeuvre .................. Totaltrack VLM ............................................................................................................. CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENT ............................................................................................................. REFERENCES ............................................................................................................................... CHAPTER 6 TRACHEAL TUBE INTRODUCERS, STYLETS, EXCHANGE CATHETERS, AND STAGED EXTUBATION SETS IN AIRWAY MANAGEMENT ............................................ María Jesús Galán Arévalo, Javier Béjar García, Alicia Ruiz Escobar and Enrique Platas Gil TRACHEAL TUBE INTRODUCERS AND STYLETS ............................................................. Endotracheal Tube Introducer ................................................................................................. Stylets ...................................................................................................................................... Lighted Stylet ................................................................................................................. Optical Stylets ............................................................................................................... EXCHANGE CATHETERS AND STAGED EXTUBATION SETS IN AIRWAY MANAGEMENT ............................................................................................................................ PATIENTS THAT NEED SPECIAL EXTUBATION MAY BE CATEGORIZED IN ONE OF THESE THREE CASES ......................................................................................................... COMPLICATIONS ASSOCIATED WITH EXTUBATION ..................................................... CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENT ............................................................................................................. REFERENCES ............................................................................................................................... CHAPTER 7 AN UPDATE ON CAN'T INTUBATE, CAN'T OXYGENATE SITUATION (CICO) SCENARIOS .............................................................................................................................. María Eugenia Centeno Robles, Emilio Herrero Gento, María Paez Hospital and María Elena Pinilla Carbajo INTRODUCTION .......................................................................................................................... MANAGEMENT OF UNANTICIPATED DIFFICULT TRACHEAL INTUBATION IN ADULTS .......................................................................................................................................... CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ............................................................................................................................... CHAPTER 8 AN UPDATE ON BRONCHOSCOPY AND OTHER AIRWAY DEVICE UPDATES ................................................................................................................................................ Norma Aracil Escoda, Ana Tirado Errazquin, Elena Sáez Ruiz, Paloma Muñoz Saldaña1 and Olivia Espinosa de los Monteros INTRODUCTION .......................................................................................................................... HISTORY ........................................................................................................................................ DESCRIPTION ............................................................................................................................... TYPES OF BRONCHOSCOPY .................................................................................................... DIFFERENT TYPES OF FLEXIBLE INTUBATING SCOPE ................................................ The Classic Fiberscope ........................................................................................................... Flexible Video Bronchoscopes ...............................................................................................

63 63 70 71 71 71 71 74 74 75 76 76 77 79 81 83 85 86 86 86 86 89 89 90 94 94 94 94 94 96 96 97 98 98 99 99 100

INDICATIONS OF FLEXIBLE INTUBATING SCOPE .......................................................... EQUIPMENT .................................................................................................................................. Oral Airway ............................................................................................................................ Ovassapian Intubating Airway ...................................................................................... Berman II Intubation Airway ........................................................................................ Williams Intubation Airway .......................................................................................... VAMA Intubation Airway .............................................................................................. Facemask ................................................................................................................................. Patil-Syracuse Mask ...................................................................................................... Endoscopy Mask VBM Medizintechnik ......................................................................... Endotracheal Tube (ETT) ....................................................................................................... USES OF FLEXIBLE INTUBATING SCOPE ........................................................................... Videolaryngoscopes ................................................................................................................ CONTRAINDICATIONS AND DISADVANTAGES OF FLEXIBLE INTUBATING SCOPE ............................................................................................................................................. CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ...............................................................................................................................

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CHAPTER 9 AN UPDATE ON AWAKE INTUBATION MANAGEMENT ................................. María Luisa Mariscal Flove, Claudia Palacios Muñoz, Rocío Castellanos González María Jesús Jiménez Gascla and Sonia Martín Ventura INTRODUCTION .......................................................................................................................... Indications ............................................................................................................................... Contraindications .................................................................................................................... LOCAL ANAESTHESIA .............................................................................................................. Local Anesthetics .................................................................................................................... Lidocaine ....................................................................................................................... Cocaíne ......................................................................................................................... Vasoconstrictor Agents .......................................................................................................... Oxymetazoline 0.1% ...................................................................................................... Phenylephrine ............................................................................................................... Local Anesthesia Techniques ................................................................................................. Topical Anesthesia ........................................................................................................ Fogging ................................................................................................................................... Nerve Blocks ........................................................................................................................... Techniques of Local Anesthesia in The Hospital Universitario de Getafe (HUG) ................ Sedation ................................................................................................................................... WHAT IS CHANGING CURRENTLY? ..................................................................................... CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENT ............................................................................................................. REFERENCES ...............................................................................................................................

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CHAPTER 10 AN UPDATE ON THE SEDATIVE AGENTS ON AWAKE INTUBATION ....... Maria Aliaño Piña and Miguel Ángel Fernández Vaquero INTRODUCTION .......................................................................................................................... SEDATIVE AGENTS .................................................................................................................... Benzodiazepines .....................................................................................................................

108 109 109 109 109 109

112 112 112 113 113 113 114 114 114 114 114 114 116 116 116 119 119 120 121 121 121 121 123 123 124 125

Midazolam ..................................................................................................................... Opioids .................................................................................................................................... Fentanyl ......................................................................................................................... Remifentanil .................................................................................................................. Hypnotics ................................................................................................................................ Propofol ......................................................................................................................... Sevoflurane .................................................................................................................... Dexmedetomidine .......................................................................................................... Contraindications .................................................................................................................... CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ...............................................................................................................................

125 125 125 125 126 126 127 127 129 130 130 130 130 131

CHAPTER 11 AN UPDATE ON PAEDIATRIC AIRWAY MANAGEMENT .............................. Gema Pino Sanz and María Dolores Méndez Marín AIRWAY ANATOMY ................................................................................................................... AIRWAY PHYSIOLOGY ............................................................................................................. CLINICAL SITUATIONS OF EXPECTED DIFFICULT AIRWAY ...................................... FACE MASK VENTILATION ..................................................................................................... PREDICTORS OF DIFFICULT AIRWAY ................................................................................ RAPID SEQUENCE INDUCTION .............................................................................................. SUPRAGLOTTIC AIRWAY DEVICES ..................................................................................... LARYNGOSCOPY AND TRACHEAL INTUBATION ............................................................ ALTERNATIVE TECHNIQUES TO OPTIMIZE LARYNGOSCOPY .................................. GUIDELINE FOR THE UNEXPECTED DIFFICULT AIRWAY IN PEDIATRIC PATIENTS ...................................................................................................................................... Difficult Mask Ventilation During Anesthesia Induction ....................................................... Step A: It Considers Three Interventions to Check ....................................................... Step B: Consider to Insert an Oropharyngeal Airway Device ...................................... Step C: Insert a Supraglottic Airway Device (SAD) ..................................................... Unanticipated Difficult Tracheal Intubation During Induction of Anesthesia in a Child Aged 1 to 8 Years ............................................................................................................................. Step A: Initial Intubation Plan when MV is Satisfactory .............................................. Step B: Secondary Tracheal Intubation Plan ................................................................ Cannot Intubate and Cannot Ventilate (CICV) in a Paralyzed Anaesthetized Child 1 to 8 Years ...................................................................................................................................... Step A: Continue to Attempt Oxygenation and Ventilation ........................................... Step B: Attempt Wake Up if Maintaining SpO2 > 80% ................................................ Step C: Airway Rescue Technique for CICV (SpO2< 80% and Failing) and/or Heart Rate Decreasing ............................................................................................................ EXPECTED DIFFICULT AIRWAY IN PEDIATRIC PATIENT .......................................... CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ...............................................................................................................................

133 133 134 135 135 137 138 139 139 142 145 146 146 147 147 148 148 149 150 150 150 151 151 152 153 153 153 153

CHAPTER 12 AN UPDATE ON OBSTETRIC AIRWAY MANAGEMENT ................................ 157 Mónica San Juan Álvarez, Marta Chacón Castillo, Adriana Carolina Orozco Vinasco, María de la Flor Robledo and Concepción Rodríguez Bertos

INTRODUCTION .......................................................................................................................... SPECIFIC CONSIDERATIONS OF THE OBSTETRIC AIRWAY ........................................ SAFE GENERAL ANAESTHESIA IN THE OBSTETRIC PATIENT .................................... Pre-operative Evaluation ......................................................................................................... Fasting and Antacid Prophylaxis ............................................................................................ Planning and Preparation ........................................................................................................ Patient Positioning .................................................................................................................. Preoxygenation ....................................................................................................................... Cricoid Pressure ...................................................................................................................... Anaesthetic Induction ............................................................................................................. Face Mask Ventilation during Apnoea ................................................................................... First Intubation Attempt .......................................................................................................... Second Intubation Attempt ..................................................................................................... FAILED TRACHEAL INTUBATION ......................................................................................... CANNOT INTUBATE, CANNOT OXYGENATE ..................................................................... AWAKEN PATIENT VS CONTINUED SURGERY ................................................................. EXTUBATION ............................................................................................................................... TEACHING AND LEARNING .................................................................................................... CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ...............................................................................................................................

157 158 159 160 160 161 161 162 163 163 164 164 165 165 167 167 168 169 170 170 170 170 170

CHAPTER 13 AN UPDATE ON MORBID OBESITY AIRWAY MANAGEMENT ................... Orreaga Zugasti Echarte, María Polo Gil, Susana Hernandez García, Ainhoa Amat Remírez and Maider Valencia Alzueta INTRODUCTION .......................................................................................................................... ANATOMY CHANGES IN OBESITY ........................................................................................ Respiratory System ................................................................................................................. Sleep-Disordered Breathing .................................................................................................... Difficult Airway Predictors and Tests .................................................................................... PREOPERATIVE AIRWAY ASSESSMENT ............................................................................. AIRWAY MANAGEMENT .......................................................................................................... Preoxygenation ....................................................................................................................... Patient Positioning .................................................................................................................. Tracheal Tubes ........................................................................................................................ Introducers .............................................................................................................................. Supraglottic Airway Devices .................................................................................................. Videolaryngoscopes ................................................................................................................ Surgical Airway ...................................................................................................................... Extubation and Postoperative Oxygenation ............................................................................ CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ...............................................................................................................................

175 175 176 176 178 178 180 180 180 181 183 183 183 183 184 184 186 186 186 186

CHAPTER 14 AN UPDATE ON AIRWAY MANAGEMENT IN THE INTENSIVE CARE UNIT ......................................................................................................................................................... 189 Paula Martínez Fariñas, Ignacio Portalo González, Clara Morandeira Rivas, Barbara Algar Yañez and Enrique Platas Gil INTRODUCTION .......................................................................................................................... 189

MANAGEMENT ............................................................................................................................ Distinguish Risk of Difficult Intubation ................................................................................. Patient´s Preparation ............................................................................................................... Preoxygenation ....................................................................................................................... Anaesthesia Induction ............................................................................................................. Recruitment Manoeuvres ........................................................................................................ Intubation in the ICU Patient .................................................................................................. Direct Laryngoscopy ..................................................................................................... Videolaryngoscopy ........................................................................................................ Supraglottic Airway Devices (SAD) ...................................................................................... Fibreoptic Bronchoscope Intubation ....................................................................................... Front of the Neck Access (FONA) .......................................................................................... CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ............................................................................................................................... CHAPTER 15 AN UPDATE ON AIRWAY MANAGEMENT IN THE EMERGENCY DEPARTMENT ....................................................................................................................................... Alicia Guarnizo Ruiz and Sara Rut Arias Perez INTRODUCTION .......................................................................................................................... EVALUATION AND PREPARATION OF A DIFFICULT AIRWAY ................................... NECESSARY DEVICES AND EQUIPMENT ............................................................................ ALGORITHM ................................................................................................................................. CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ............................................................................................................................... CHAPTER 16 AN UPDATE ON PERCUTANEOUS AIRWAY MANAGEMENT ...................... Carlos Velayos Amo and Raquel del Olmo Monge INTRODUCTION .......................................................................................................................... TECHNIQUES ................................................................................................................................ Percutaneous Cricothyroidotomy ............................................................................................ Percutaneous Tracheostomy ................................................................................................... COMPARISON BETWEEN TECHNIQUES .............................................................................. PREVENTION OF COMPLICATIONS IN PERCUTANEOUS TRACHEOSTOMY BRONCHOSCOPY AND ULTRASOUND ................................................................................. Complications Facing Adverse Outcomes .............................................................................. Fibrobronchoscope .................................................................................................................. Ultrasound ............................................................................................................................... CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ...............................................................................................................................

191 191 191 192 193 194 194 194 195 197 199 199 201 202 202 202 202 205 205 206 206 208 208 209 209 209 210 212 212 214 214 217 218 222 222 224 224 225 226 226 226 226

CHAPTER 17 AN UPDATE ON AIRWAY MANAGEMENT IN ANAESTHESIA OUTSIDE THE OPERATING ROOM .................................................................................................................... Ignacio Portalo González, Flor de María Analía Sánchez Díaz, Paula Martinez Fariñas and Eugenio D. Martínez Hurtado INTRODUCTION .......................................................................................................................... ORGANIZATIONAL ASPECTS .................................................................................................. ANAESTHETIC TECHNIQUE .................................................................................................... DIFFICULT AIRWAY PREDICTION ........................................................................................ DIFFICULT AIRWAY ALGORITHMS ..................................................................................... VIDEOLARYNGOSCOPES ......................................................................................................... ADVANTAGES AND DISADVANTAGES OF VIDEOLARYNGOSCOPES ........................ CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ............................................................................................................................... CHAPTER 18 ANESTHESIOLOGIST’S ROLE IN SUPPORTING NONANESTHESIOLOGIST AIRWAY PROVIDER PRACTICE: EMERGENCY DEPARTMENT AND INTENSIVE CARE UNITS .......................................................................................................... Cristina Gil Lapetra, Jossy C. Salazar Aguirre, José Olarra Nuel, Beatriz Bolzoni Muriel and Marta Solera Toledo INTRODUCTION .......................................................................................................................... EVOLUTION OF AIRWAY MANAGEMENT AND NON-ANESTHESIOLOGISTS’ FUNCTIONS ................................................................................................................................... HEALTHCARE SYSTEMS’S ORGANISATION ACROSS COUNTRIES ............................ REVISITING THE CASE IN SPANISH HEALTHCARE FACILITIES ................................ BACKGROUND AND SKILLS REQUIRED TO ACHIEVE SUCCESSFUL RAPID SEQUENCE INTUBATION (RSI) ............................................................................................... OTHER POTENTIAL OBSTACLES .......................................................................................... ROLE OF SUPRAGLOTTIC AIRWAY DEVICES IN EMERGENCY SITUATIONS ........ DISCUSSION .................................................................................................................................. CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ............................................................................................................................... CHAPTER 19 AN UPDATE ON OUT-OF-HOSPITAL AIRWAY MANAGEMENT ................. Alfredo Serrano-Moraza and Armando J. Munayco Sánchez INTRODUCTION .......................................................................................................................... BASIC PRINCIPLES ..................................................................................................................... AIRWAY MANAGEMENT STATE OF THE ART .................................................................. First of All: Is there any Evidence about ETI Success Depending on the Model? ................. But, What is the Main Cause, the Model or the Experience? ................................................. Is RSI Safe Enough to Achieve ETI? ..................................................................................... Talking about Safety, What is the Hallmark? ......................................................................... Then, is There any Advantage between ETI and Some Alternative Devices? ....................... It is Really Needed to Emphasize the Confirmation of the ET Position? ............................... AIRWAY MANAGEMENT IN CPR ........................................................................................... AIRWAY MANAGEMENT IN MAJOR TRAUMA .................................................................. RECENT ADVANCES IN EMERGENCY AIRWAY MANAGEMENT ................................ CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................

229 230 231 231 233 233 234 235 237 237 237 237 237

240 240 241 241 243 245 246 246 247 249 250 250 250 250 253 253 255 257 257 258 259 259 259 261 261 262 263 263 263

CONFLICT OF INTEREST ......................................................................................................... 263 ACKNOWLEDGEMENTS ........................................................................................................... 263 REFERENCES ............................................................................................................................... 264 CHAPTER 20 AN UPDATE ON AIRWAY MANAGEMENT IN HIGH-THREAT ENVIRONMENTS .................................................................................................................................. Armando J. Munayco Sánchez, Alfredo Serrano Moraza, Jose Ramón Rey Fedriani and Alberto J. Hormeño Holgado INTRODUCTION .......................................................................................................................... MEDICAL SUPPORT ................................................................................................................... COMBAT CASUALTY CARE ..................................................................................................... ROTARY WING EVACUATIONS .............................................................................................. Flight Security ......................................................................................................................... Aeronautical Environment ...................................................................................................... CASUALTY CARE IN CIVILIAN SETTINGS .......................................................................... AIRWAY MANAGEMENT .......................................................................................................... CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ............................................................................................................................... CHAPTER 21 AN UPDATE ON EXTUBATION MANAGEMENT .............................................. Eugenio Daniel Martinez-Hurtado, Miriam Sanchez-Merchante, Nekari de Luis Cabezón, Javier Ripollés Melchor and Alicia Ruiz Escobar INTRODUCTION .......................................................................................................................... DEFINITIONS ................................................................................................................................ Extubation Failure ................................................................................................................... Weaning Failure ...................................................................................................................... “At Risk” Extubation .............................................................................................................. Difficult Extubation ................................................................................................................ Risk Factors ............................................................................................................................ Causes of Failure of Extubation .............................................................................................. EXTUBATION STRATEGY ........................................................................................................ Step 1: Plan ............................................................................................................................. Step 2: Prepare ........................................................................................................................ Step 3: Extubation ................................................................................................................... EXTUBATION WITH THE PATIENT ASLEEP ...................................................................... EXTUBATION AWAKE ............................................................................................................... EXTUBATION WITH TOTALTRACK® VIDEO LARYNGEAL MASK (VLM) ................ EXTUBATION ASSISTED BY AN EXCHANGER ................................................................... TRACHEOSTOMY PROCEDURE ............................................................................................. RESPIRATORY CARE IN PATIENTS WITH AIRWAY COMPROMISE ........................... DOCUMENTATION AND RECOMMENDATIONS ................................................................ CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ...............................................................................................................................

268 268 269 270 271 271 271 272 274 277 278 278 278 278 280 280 282 282 283 283 283 284 285 288 290 291 292 293 293 295 295 295 296 297 298 298 298 298 298

CHAPTER 22 AN UPDATE ON AIRWAY MANAGEMENT EDUCATION ............................... María Luisa Mariscal Flores, Alfonso Anduenza Artal, Sonia Martín Ventura, Claudia Palacios Muñoz and Rocío Castellanos González INTRODUCTION .......................................................................................................................... JUSTIFICATION ........................................................................................................................... DIFFERENT FORMS OF AIRWAY MANAGEMENT TEACHING ..................................... Technical Skills ....................................................................................................................... Basic .............................................................................................................................. Advanced ....................................................................................................................... Non-Technical Skills .............................................................................................................. VIRTUAL REALITY SIMULATION AND THE PROGRAMS THAT ALREADY EXIST A MODEL OF FORMATION IN DIFFICULT AIRWAY MANAGEMENT IN THE ANAESTHESIA SERVICE OF THE UNIVERSITY HOSPITAL OF GETAFE (MADRID, SPAIN) ............................................................................................................................................. EVALUATION AND MONITORING ......................................................................................... CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ............................................................................................................................... CHAPTER 23 AN UPDATE ON AIRWAY MANAGEMENT REGISTRY AND ORGANIZATION ................................................................................................................................... Eugenio Daniel Martinez-Hurtado, Miriam Sanchez-Merchante, Pablo Renedo Corcóstegui, Nekari de Luis Cabezón and Alicia Ruiz Escobar INTRODUCTION .......................................................................................................................... CLOSE CLAIMS PROJECT AND THE SAFETY OF PATIENTS ......................................... What should be known about patient's airway? ...................................................................... DOCUMENTATION OF CRITICAL INFORMATION ........................................................... DATABASES, RECORDS, AND CLINICAL PRACTICES ..................................................... Existing Databases .................................................................................................................. Type 1: Databases for Patient Safety ............................................................................ Type 2: Etiological and Epidemiological Databases .................................................... Type 3: Databases Combined (Epidemiological, Etiological and for the Safety of the Patient) .......................................................................................................................... Identification of Patients and Clinical Practices ..................................................................... Disclosure of the Documentation of the Anaesthesia Record ................................................ BIG DATA ....................................................................................................................................... THE PROBLEM OF INTEROPERABILITY ............................................................................ OTHER PROBLEMS .................................................................................................................... CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ............................................................................................................................... CHAPTER 24 BIBLIOMETRICS OF THE DIFFICULT AIRWAY .............................................. Miguel Ángel García Aroca, Andrés Pandiella Dominique and Ricardo Navarro Suay INTRODUCTION .......................................................................................................................... THE SEARCH FOR BIBLIOMETRIC INFORMATION ON DIFFICULT AIRWAY ........ Web of Science ....................................................................................................................... Scopus ..................................................................................................................................... The Difficult Airway through Web of Science and Scopus ...................................................

300 300 301 302 303 303 303 305 306 307 309 310 310 310 310 310 312 312 314 315 315 317 317 318 318 318 318 319 321 321 323 324 324 324 325 325 328 328 329 329 330 330

PRODUCTIVITY IN DIFFICULT AIRWAY ............................................................................ Productivity by Author ........................................................................................................... Productivity by Institution ...................................................................................................... COLLABORATION IN DIFFICULT AIRWAY ........................................................................ IMPACT ON DIFFICULT AIRWAY .......................................................................................... CONCLUSION ............................................................................................................................... CONSENT FOR PUBLICATION ................................................................................................ CONFLICT OF INTEREST ......................................................................................................... ACKNOWLEDGEMENTS ........................................................................................................... REFERENCES ...............................................................................................................................

331 332 332 333 336 337 337 338 338 338

SUBJECT INDEX .................................................................................................................................... 341

i

PREFACE I We have tried to create a work that approaches the latest developments in the field of airway management. To achieve this purpose, we created alliances with the best experts and most qualified professionals of recognized prestige in this field who reviewed the new preoperative diagnostic methods, the new intubation devices, the new ways of handling extubation, the novelties in postoperative management in the resuscitation units, the management of the airway of those patients in remote areas outside the operating room or in extreme situations, and all the news that may be of interest to our colleagues. Always trying to achieve a simple, easy, and direct reading that will be helpful in the daily work. From my role as the unifier of the authors and their chapters, I want to thank each of my colleagues for their work. The present book "Recent Advances in Anesthesiology Vol. 3 – An Update on Airway Management" emerged as an opportunity to unite the knowledge of those expert colleagues in this area and transmit it to readers interested in the subject, and I think we have achieved it. Finally, I want to thank my father, Dr. Vicente Martinez Navas, specialist in Internal Medicine, Pediatrics, Preventive Medicine, Epidemiology, Microbiology, General Medicine, as well as Military Doctor. One of the best, most trained and outstanding Spanish doctors of his generation. He instilled in me a humanistic mentality of medicine, fundamental when planning and approaching this kind of work. I also want to thank my mother for being the non-medical counterpoint in my life. Without them, I would never have reached where I am, and this book would not have seen the light.

Eugenio Daniel Martinez-Hurtado Department of Anesthesiology and Intensive Care, University Hospital Infanta Leonor, Madrid, Spain

ii

PREFACE II The Difficult Airway (DA) management is a challenge for anesthesiologists and for all those professionals who are related to it. Over the years, their knowledge and practice evolved to a great extent, becoming in most of the Services a known, practiced, and respected activity. Since the times when they were only used as handling devices to solve the DA, the laryngoscope, face mask, stylet, and guedel, until now, with a large number of Supraglottic Devices, Videolaryngoscopes, and Fibroscopes, have changed the DA approach significantly. However, we must not forget that the important thing is to assess the patient's airway and, with this knowledge, establish an action strategy with alternative plans based on theoretical knowledge and practical ability with the different devices and in the follow-up of DA Algorithms of each hospital. With this book, "Recent Advances in Anesthesiology Vol. 3 – An Update on Airway Management", we intend to update the knowledge of all those novelties that have been emerging in this field. We trust that it will be easy to read at the same time as deep and allow readers an update on the management of the difficult airway.

María Luisa Mariscal Flores Department of Anesthesiology and Intensive Care, Hospital Universitario de Getafe, Madrid, Spain

iii

PREFACE III This book entitled “Recent Advances in Anesthesiology Vol. 3 – An Update on Airway Management” is an excellent tool for learning about Airway management, which remains one of the pillars of anaesthesiology and critical care in a variety of "scheduled, urgent, or emergent" situations. The scope of action can be in hospital but also extrahospital, with all the connotations of difficulty that the latter usually possess. Unquestionably, the advances in devices to improve our ability to control the airway have been momentous in recent decades, particularly through the incorporation of different devices with built-in optics. These include video laryngoscopes, with or without a channel, that have irrefutably revolutionized our usual clinical practice, specifically useful for the unforeseen difficult airway (DA), but also for some cases of anticipated DA. This means that in the last Difficult Airway Society (DAS) guidelines, this device is already within Plan A of the algorithm. The inclusion of fiberscope in our daily clinical practice has also been very helpful as instruments that all specialists who need to manage the airway should know and be trained in its proper use. Furthermore, we must not forget the fundamental importance of the supraglottic devices that are described in detail in this work, or the intubation guidelines, stylets, tube interchanges and guide for safe extubation by stages, insomuch as extubation is one of the most dangerous moments where we must anticipate all possible secure clinical alternatives. Of course, the optimal management of DA requires a prior study of the patient to guide the most appropriate technique in each patient, which has been fundamental to improve the quality and safety of these procedures. However, the predictors are not always reliable, so more studies should be conducted to improve the prediction of DA. Training in airway management is perhaps the most important aspect from my modest point of view, so this work can contribute a lot to update this matter and specify how to act with the new guidelines endorsed by experts such as the participating authors in the same. Undoubtedly, the learning of airway management through clinical simulation is essential for any professional who requires training in this type of technique. In summary, I sincerely believe that this work will contribute to a better knowledge of safe clinical practice and quality control of the airway in all types of clinical situations.

Manuel Granell Gil Universidad de Valencia, Médico Jefe de Sección de Anestesiología, CHGUV. Vocal de Torácica (SEDAR) y del Thoracic SubCommittee (EACTA), Valencia Spain

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INTRODUCTION All anesthesiologists know that the highest morbidity and mortality associated with anaesthesia are related to the airway management of our patients. This area represents one of the basic pillars of the specialty, and the Difficult Airway is the undisputed protagonist in all the congresses and the subject of numerous publications periodically. Airway management has been changing over the years. Progressively, the evaluation and prediction of the possible difficulty in ventilation, oxygenation and intubation in the preoperative assessment have been standardized, while numerous devices have appeared that facilitate the way to approach the handling of the Difficult Airway. It is no longer just about knowing how to use the fiberoptic bronchoscope, although this is still the main tool for managing the Difficult Airway. We are also obliged to know and use a wide range of new devices, as well as the indications and peculiarities of each of them. Unfortunately, this great quantity of available devices means that many times we do not know them well, nor do we differentiate them. And, therefore, in many occasions, we do not use them in an adequate way. It does not consist in having and using all, but in mastering the use of those we have and acquiring experience with them so that they are effective when a Difficult Airway situation arises. This book “Recent Advances in Anaesthesiology Vol. 3 – An Update on Airway Management” is an update of those topics that have had an important development in recent years in airway management. We have tried to approach the latest developments in this field with a simple, easy and direct reading, which helps in professionals' daily work. We intend to reach a multitude of colleagues from all medical areas who have to manage their patients' airways: anaesthesiologists, intensivists, intra- and extra-hospital emergency physicians, pneumologists, and ENT surgeons who we believe could be of support for your work. We also believe that it may be of interest to residents in training, as a method of updating a subject that is basic and without which, almost all others are impossible to carry out.

v

List of Contributors Adriana Carolina Orozco Vinares

Departamento de Anestesiología y Reanimación, Universitario Severo Ochoa, Leganes, Madrid, Spain

Hospital

Ainhoa Amat Remírez

F.E.A. Anestesiología y Reanimación, Hospital García Orcoyen. Estella, Estella, Navarra, Spain

Alfonso Anduenza Artal

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Fundación Alcorcón, Madrid, Spain

Alberto Joaquin Hormeño Holgado

Unidad Médica Aérea de Apoyo al Despliegue de Madrid (UMAAD Madrid), Ejército de Aire, Madrid, Spain

Alfredo Serrano-Moraza

Servicio de Urgencias Médicas Summa 112, Madhid, Spain

Alicia Guarnizo Ruiz

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Infanta Cristina, Parla, Madrid, Spain

Alicia Ruiz Escobar

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Infanta Leonor, Madrid, Spain

Ana Tirado Errazquin

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Infanta Leonor, Madrid, Spain

Andrés Pandiella-Dominique

Research Institute on Higher Education and Science (INAECU), Madrid, Spain

Armando J. Munayco Sánchez

Unidad Médica Aérea de Apoyo al Despliegue de Madrid (UMAAD Madrid), Ejército de Aire, Madrid, Spain

Barbara Algar Yañez

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Infanta Leonor, Madrid, Spain

Beatriz Bolzoni Marciel

Department of Anaesthesia, and Critical Care Medicine, University Hospital of Fuenlabrada, Madrid, Spain Rey Juan Carlos University, Alcorcón, Madrid, Spain

Carlos Velayos Amo

Médico Especialista en Medicina Intensiva, Servicio de Medicina Intensiva, Hospital Universitario de Fuenlabrada, Fuenlabrada, Madrid, Spain

Clara Morandeira Rivas

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Fundación Alcorcón, Madrid, Spain

Claudia Palacios Muñoz

Department of Anaesthesiology and Critical Care Medicine, Hospital Universitario de Getafe, Madrid, Spain

Concepcion Rodríguez Bertos

Departamento de Anestesiología y Reanimación, Universitario Severo Ochoa, Leganes, Madrid, Spain

Cristina Gil Lapetra

Department of Anesthesiology and Critical Care Medicine, University Hospital of Fuenlabrada, Madrid, Spain

Eduardo González Constán

Department of Anesthesiology, La Plana University Hospital, Ctra, Vila-real – Burriana km 0,5, 12540 Vila-real, Castellón, Spain

Elena Sáez Ruiz

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Infanta Leonor, Madrid, Spain

Hospital

vi Emilio Herrero Gento

Departamento de Anestesiología y Reanimación, Complejo Asistencial Universitario de Palencia, Palencia, Spain

Enrique Platas Gil

Servicio de Medicina Intensiva, Hospital Universitario de la Princesa, Madrid, Spain

Eugenio Daniel MartinezHurtado

Department of Anaesthesiology and Intensive Care, University Hospital Infanta Leonor, Madrid, Spain

Flor de María Analía Sánchez Díaz

Department of Anesthesiology and Critical Care Medicine, Complejo Asistencial Universitario de León, León, Spain

Flor María Rey Tabasco

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario de Getafe, Madrid, Spain

Gema Pino Sanz

Department of Pediatric Anesthesia, Critical Care and Pain, Children´s Hospital Doce De Octubre, Madrid, Spain

Guillermo Navarro

Department of Anesthesiology and Critical Care Medicine, “Hospital de Emergencias Dr. Clemente Álvarez”, Ciudad de Rosario, R., Argentina

Ignacio Portalo González

Department of Anesthesiology and Critical Care Medicine, Hospital Infanta Cristina, Parla, Madrid, Spain

Javier Béjar García

Department of Anesthesiology and Critical Care Medicine, Clínica CEMTRO, Madrid, Spain

Javier Ripollés Melchor

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Infanta Leonor, Madrid, Spain

José Olarra Nuel

Department of Anaesthesiology and Critical Care Medicine, University Hospital of Fuenlabrada, Madrid, Spain Department Of Basic Sciences, Pharmacology, University of Rey Juan Carlos, Alcorcón, Madrid, Spain

Jose Ramón Rey Fedriani

Unidad Militar de Emergencias (UME), Primer Batallón de Intervención, Madrid, Spain

Jossy C. Salazar Aguirre

Department of Anesthesiology and Critical Care Medicine, University Hospital of Fuenlabrada, Madrid, Spain

Maider Valencia Alzueta

F.E.A. Anestesiología y Reanimación, Complejo Hospitalario de Navarra. Pamplona, Navarra, Spain

Manuel Granell Gil

Universidad de Valencia, Médico Jefe de Sección de Anestesiología, CHGUV, Vocal de Torácica (SEDAR) y del Thoracic SubCommittee (EACTA), Valencia, Spain

Maria Aliaño Piña

Department of Anesthesiology and Critical Care, Clínica Universidad de Navarra. Calle Marquesado de Sta, Marta, 1, 28027 Madrid, Spain

Maria Aymerich De Franceschi

Department of Anesthesiology and Critical Care, Clínica Universidad de Navarra. Calle Marquesado de Sta, Marta, 1, 28027 Madrid, Spain

Maria de la Flor Robledo

Profesora asociada universidad Alfonso x el Sabio, Madrid, Spain Departamento de Anestesiología y Reanimación, Hospital Universitario Severo Ochoa, Leganes, Madrid, Spain

vii María Dolores Méndez Marín

Department of Pediatric Anesthesia, Critical care and Pain. Children´s Hospital Doce De Octubre, Madrid, Spain

María Elena Pinilla Carbajo

Departamento de Anestesiología y Reanimación, Complejo Asistencial Universitario de Palencia, Palencia, Spain

María Eugenia Centeno Robles

Departamento de Anestesiología y Reanimación, Complejo Asistencial Universitario de Palencia, Palencia, Spain

María Jesús Galán Arévalo

Department of Anesthesiology and Critical Care Medicine, Clínica CEMTRO, Madrid, Spain

María Jesús Jiménez García

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario de Getafe, Madrid, Spain

María Luisa Mariscal Flores

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario de Getafe, Madrid, Spain

María Paez Hospital

Departamento de Anestesiología y Reanimación, Complejo Asistencial Universitario de Palencia, Palencia, Spain

María Polo Gil

F.E.A. Anestesiología y Reanimación, Hospital García Orcoyen. Estella, Estella, Navarra, Spain

Marta Chacón Castillo

Departamento de Anestesiología y Reanimación, Universitario Severo Ochoa, Leganes, Madrid, Spain

Marta Solera Toledo

Department of Anesthesiology and Critical Care Medicine, University Hospital of Fuenlabrada, Madrid, Spain

Miguel A. García-Aroca

Anesthesia and Critical Care Unit, Hospital Central de la Defensa "Gómez Ulla", Madrid, Spain Glorieta del Ejército número 1, CP: 28047 Madrid, Spain

Miguel Ángel Fernández Vaquero

Department of Anesthesiology and Critical Care, Clínica Universidad de Navarra. Calle Marquesado de Sta, Marta, 1, 28027 Madrid, Spain

Miriam Sanchez-Merchante

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Fundación Alcorcón, Madrid, Spain Bioethics expert, Rey Juan Carlos University, Madrid, Spain Mindfulness in Health Contexts Expert, Complutense University, Madrid, Spain

Monica San Juan Álvarez

Profesora asociada universidad Alfonso X el Sabio, Madrid, Spain Departamento de Anestesiología y Reanimación, Hospital Universitario Severo Ochoa, Leganes, Madrid, Spain

Monir Kabiri Sacramento

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Infanta Leonor, Madrid, Spain

Montiel Redondo Castillo

Department of Anesthesiology, La Plana University Hospital. Ctra. Vila-real – Burriana km 0,5, 12540 Vila-real, Castellón, Spain

Nekari de Luis Cabezón

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario de Basurto, Bizkaia, Spain

Norma Aracil Escoda

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Infanta Leonor, Madrid, Spain

Hospital

viii Olivia Espinosa de los Monteros

Department of Cellular Pathology, John Radcliffe Hospital, Oxford, UK

Orreaga Zugasti Echarte

F.E.A. Anestesiología y Reanimación, Complejo Hospitalario de Navarra, Pamplona, Navarra, Spain

Pablo Renedo Corcóstegui

Department of Anesthesiology and Critical Care Medicine, OSI Alto Deba, Mondragón, Guipúzcoa, Spain

Paloma Muñoz Saldaña

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Infanta Leonor, Madrid, Spain

Paula Martínez Fariñas

Department of Anesthesiology and Critical Care Medicine, Hospital FREMAP Majadahonda, Madrid, Spain

Raquel del Olmo Monge

Médico Especialista en Medicina Intensiva, Servicio de Medicina Intensiva. Hospital Universitario de Fuenlabrada, Fuenlabrada, Madrid, Spain

Ricardo Navarro-Suay

Anesthesia and Critical Care Unit, Hospital Central de la Defensa “Gómez Ulla”, Madrid, Spain Glorieta del Ejército número 1, CP: 28047 Madrid, Spain Associate Professor of Anesthesia, University of Alcalá, Madrid (Spain). Instituto Mixto de Investigación Biosanitaria de la Defensa (IMIDEF), Madrid, Spain

Rocío Castellanos González

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario de Getafe, Madrid, Spain

Sara Rut Arias Pérez

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Infanta Cristina, Parla, Madrid, Spain

Sonia Martín Ventura

Department of Anesthesiology and Critical Care Medicine, Hospital Universitario de Getafe, Madrid, Spain

Susana Hernández García

F.E.A. Anestesiología y Reanimación, Complejo Hospitalario de Navarra. Pamplona, Navarra, Spain

Recent Advances in Anesthesiology, 2020, Vol. 3, 1-14

1

CHAPTER 1

An Update on Diagnostic Accuracy (CT, X-ray) for Airway Management Montiel Redondo Castillo* and Eduardo González Constán Department of Anaesthesiology, La Plana University Hospital, Vila-real (Castellón), Spain Abstract: Diagnostic imaging tests play an increasingly important role in diagnosing a difficult airway. The variety of tests and their relatively easy availability provide anaesthesiologists with valuable information regarding the challenge of potential difficulty in managing airways. In this chapter, the radiological parameters proven most useful in the various imaging techniques commonly employed in clinical practice will be reviewed: conventional radiology, computed tomography, and ultrasonography.

Keywords: Acromegaly, Airway assessment, Airway sonography, Computed tomography, Cormack-Lehane grade, Cervical soft tissue, Difficult intubation, Difficult Laryngoscopy, Difficult airway, Diagnostic odds ratios, Hyomental distance, Lateral neck radiography, Morbid obesity, Positive predictive value, Radiological indicator, Thyromental distance, Ultrasound, X-ray. BACKGROUND Although a difficult airway (DA) is a low prevalence clinical condition, it presents a true challenge for anaesthesiologists due to the severe consequences resulting from inefficient management [1, 2]. There has been a noticeable reduction in recent decades in mortality attributable to anaesthesia [3]; however, up to 40% of deaths and severe sequela are still related to airway management [4]. A significant portion of the difficulties in airway management is unexpected [5], and most classical clinical tests employed to convert an unforeseen DA into a predicted DA have a poor predictive capacity [6 - 8]. Various imaging techniques have therefore been employed in recent years to improve the predictive capacity of classical tests. Computed tomography (CT), magnetic resonance imaging (MRI), conventional radiology (X-rays), and Corresponding author Montiel Redondo Castillo: Department of Anaesthesiology, La Plana University Hospital, Vila-real (Castellón) 12540, Spain; Tel/Fax: 0034 964 39 97 75; E-mail: [email protected]

*

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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ultrasound are recommended for assessing DA [9 - 13]. This chapter reviews the indices in imaging techniques that provide the most value in DA management. To provide more consistency and make the results more understandable, the positive predictive value (PPV) and diagnostic odds ratio (DOR) for each radiological index discussed in this chapter were calculated. Given that the PPV is dependent on the prevalence of the disease, the value will be adjusted, considering a theoretical prevalence of difficult laryngoscopy of 10%. DOR is a measure that integrates the sensitivity and specificity of a diagnostic test and is considered an appropriate global indicator for comparing the accuracy of various diagnostic tests [14]. CONVENTIONAL RADIOLOGY The images provided by conventional radiology, even without being specifically requested for the airway assessment, can provide important information on the anatomy and possible pathology of that anatomy, which can alert anaesthesiologists to potential difficulties during airway management [15]. To this end, studies are underway that seek to relate the anthropometric measures of radiological images that act as predictors of DA and have already shown promising results. The lateral cervical radiography projection can provide an almost complete view of the upper airways, because they are shown incidentally, due to anatomical reference points (bone and cartilage) that help to delimit the airways. The nasopharynx, oropharynx, hypopharynx, larynx and, depending on the extent of the study, the proximal trachea can be clearly differentiated [15] (Fig. 1). As a result, most evaluated radiological indicators have been obtained by measuring the distances and angles between bone structures and laryngeal cartilages, which are easily identifiable in lateral neck radiography. One of the most complete studies in terms of the number of measurements and angles evaluated in the bone structures of the lateral neck radiography is the study by Xu et al. conducted on patients with cervical spondylosis [16], with a total of 12 bone distances, 2 angles in the cervical vertebrae, and 4 angles in the axes of the mouth, pharynx, and larynx, measured in the neutral, extension and flexion positions. After comparing the measurements with the Cormack-Lehane laryngoscopic grading system, the authors obtained 12 significantly different radiological indicators, 2 of which were identified with better correlation in predicting DA: one was the angle between the lines that pass through the base of the C2 and C6 vertebral bodies in the head’s neutral position (angle C2-C6), and the second was the difference between the angle between the epiglottal and

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laryngeal axes in the neutral to extension position. However, the calculated PPV for a C2-C6 angle greater than 12.1° is 21% with a DOR of 5, and therefore, appears to not be an accurate indicator.

Fig. (1). Anatomical airway landmarks on the lateral cervical X-ray film in neutral position. NP: nasopharynx; OP: oropharynx; HP: hypopharynx; H: hyoid bone; E: epiglottis; T: thyroid cartilage; C: cricoid cartilage.

Kamalipour et al. [17] focused their measurements on the laryngeal structures, taking as reference points the hyoid bone, epiglottic cartilage, arytenoid cartilage, and thyroid cartilage. Two angles stand out: angle α’, formed by the line that joins the hyoid bone to the thyroid cartilage and the line that joins the latter with the

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arytenoid cartilage (this second line corresponds to the location of the vocal cords) and angle β’, which is between the lines that join the hyoid bone to the base and to the tip of the epiglottis (Fig. 2). The study results on 100 evaluated patients were noteworthy, achieving 100% sensitivity, specificity, and PPV in predicting DA when taking a low angle of graduation. Based on angle β’, the authors suggested a simple method to assess the ease of intubation, which they called the EHE’ triangle or triangle of safety, whose vertices are the hyoid bone, the base of the epiglottis, and the tip of the epiglottis. The presence of this triangle is correlated to the ease of intubation, and its absence predicts difficulty. The established cut-off is a β’ angle ≤9.1° with a PPV of 100%.

Fig. (2). Lateral x-ray of the neck. β-angle is in yellow and α-angle is in orange. After connecting E, E’ and H a triangle is formed, named EHE’ triangle. E: tip of the epiglottis; E’: base of the epiglottis; H: hyoid bone.

Based on the same angles, Liu et al. [18] performed the measurements on Chinese patients. The study data showed that angles α’ and β’ are more accurate than the modified Mallampati test (MMT) and the thyromental distance in terms of

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sensitivity, specificity, and PPV. The authors also found that angle α’ is a better radiological indicator than angle β’, with a resulting PPV of 42% and DOR of 43 for an angle α’ ≤85.52°. Angle α’ is, therefore, an easy angle to measure because if it is smaller than 90°, there would be fewer possibilities of difficulty in tracheal intubation. One of the studies notable for the number of included patients is the one by Khan et al. [19], with data from 4500 patients. Measurements were performed of bone structures, especially in the jaw, which were compared with clinical tests and the Cormack-Lehane grade. The study results revealed that none of the radiological measurements were superior to the clinical upper lip bite test and that the only radiological indicator comparable to the clinical tests was the mandibulo-hyoid distance (the perpendicular distance from the hyoid bone to the jaw), although without outperforming the bite test. This indicator presented a PPV of 45% and a DOR of 27 for a mandibulo-hyoid distance shorter than 40 mm. Another radiological bone indicator studied by Gupta et al. [20] is the maxillopharyngeal angle, which is formed by joining the line of the upper jaw axis that runs parallel to the hard palate with the line of the pharyngeal axis that passes through the anterior part of the C1 and C2 vertebral bodies (Fig. 3). Measured with the head in the neutral position, this angle is typically greater than 100°. When measuring the angle electronically in 157 patients, an increase was observed in the difficulty of laryngoscopy for values below 90°. Lastly, Lee et al. [21] studied the airways in patients with acromegaly, finding as a predictor of DA (also at the bone level) the distance from the alveolar line of the mandible to the hyoid bone, with a PPV of 22% and DOR of 12 for a value greater than 48 mm. Of all the radiological indicators described, it appears that those based on the cartilage structures of the larynx with a higher DOR could be more advantageous at the statistical level than measurements of bone structures in predicting DA. In truth, radiographic images represent a simple, non-invasive, economical, and easily reproducible assessment method. The disadvantage of conventional radiography is exposure to ionising radiation. It is important to know that the radiation dose of lateral neck radiography is approximately 0.1 millisievert (mSv) and that of chest radiography is 0.2 mSv. These are therefore acceptable doses, because the effective dose limit considered safe for the population is 1 mSv per year, according to the directives of the European Union [22]. However, when the clinical evaluation predicts a difficult airway, studies that demonstrate the cost-effectiveness of radiographic evaluation are still lacking.

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Fig. (3). Lateral x-ray of the neck showing the normal maxillo-pharyngeal angle.

COMPUTED TOMOGRAPHY CT is currently one of the best modalities for obtaining images due to its spatial resolution and because it presents images in 3 layers and creates 3D and volumetric reconstructions (Fig. 4). CT also helps accurately visualise bone structures and the various organs in an easily recognisable anatomical form [15].

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Fig. (4). Volumetric reconstructions (property image of E.M. Hurtado. Editor).

In the search for potential radiological indicators that help predict DA, Naguib et al. [9] employed 3D CT reconstructions of the upper airways from 52 patients. The authors assessed the following measures: 1) distance from the most posterior aspect of the base of the tongue to the posterior pharyngeal wall; 2) distance from the uppermost posterior aspect of the epiglottis to the posterior pharyngeal wall; 3) distance between the tip of the uvula and the posterior pharyngeal wall; 4)

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distance between the uppermost visible part of the airway at the vocal cord level and the posterior pharyngeal wall at the piriform sinus level; 5) length of the epiglottis; 6) angle between the epiglottis and the tongue; 7) angle between the long axis of the pharynx and long axis of the larynx; and 8) the angle between the long axis of the larynx and the trachea. However, none of these parameters achieved a significant result for discerning those patients with intubation difficulty. More recently, Lee et al. [21] measured the area of the tongue using CT in patients with acromegaly and found that a larger tongue was associated with difficulty in the laryngoscopy. The results showed that a tongue area greater than 2600 mm2 offered a PPV of 18% and DOR of 5, showing that the tongue area is a fairly deficient indicator. CT is superior for assessing tracheal anatomy and airway disease. Anaesthetists, therefore, need to continue searching for potential radiological indicators of DA. Nevertheless, it needs to consider the limitations due to the risk of radiation exposure and therefore not consider CT a routine examination for airway assessment. And, in some countries, the cost can also be deterrent. ULTRASONOGRAPHY Airway ultrasonography can be helpful for assessing and managing DA [23]. Although the various assessed indices do not have the desired predictive capacity per se, they can significantly improve the diagnostic yield by combining them with classical clinical tests. Ultrasound machines are currently available in most surgical areas, and their use has become widespread among anaesthesiologists [24]. In addition, ultrasonography has easy point-of-care availability and no radiation for the patient, unlike other imaging tests such as X-rays and CT. Most ultrasound indices for assessing DA are focused on quantifying the amount of soft tissue in the neck or floor of the mouth [25 - 29]. Other indices, in contrast, assess the visualisation of anatomical structures or the distance between them [30, 31]. Wu J et al. [25] studied the relationship between laryngoscopy difficulty and the anterior neck soft tissue thickness at the hyoid bone (DSHB) measured by ultrasonography (Fig. 5). The authors analysed 203 patients and found that the cut-off with the best discriminatory power was a DSHB index of 1.28 cm. Although the authors concluded that this ultrasound parameter was an independent predictor of difficult

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laryngoscopy, both the PPV and DOR were of little clinical utility (39% and 35%, respectively).

Fig. (5). Ultrasound measurement of anterior neck soft tissue thicknesses. Yellow dotted line denotes the distance from skin to hyoid bone (DSHB).

Ezri et al. measured the distance from the skin to the anterior aspect of the trachea at the vocal cords (ANS-VC) in a sample of 50 patients with morbid obesity [26]. When the authors related this index to the laryngoscopy difficulty, they observed excellent discrimination when using an ANS-VC of 28 mm as the cut-off. The PPV was 100%, with no overlap between the easy and difficult laryngoscopy groups in terms of the ANS-VC value. Nevertheless, a sample of 50 patients (considering the low prevalence of difficult laryngoscopy) is small, because only 9 patients in the study presented laryngoscopy with a Cormack-Lehane grade of III-IV. Reddy PB et al. conducted a study that assessed the same ultrasound parameter but with a sample of 100 patients without morbid obesity [27]. These authors obtained an ANS-VC cut-off of 23 mm (Fig. 6). Surprisingly, the PPV and DOR were very poor (18% and 8, respectively), unlike those in the Ezri study. The ultrasound quantification of pretracheal soft tissue, therefore, appears to be a promising index for assessing DA in patients with morbid obesity, although more studies with larger samples are needed to confirm this parameter.

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Fig. (6). Transverse ultrasound view of the anterior cervical soft tissue at the level of the vocal cords. LVC: Left Vocal Cord. RVC: Right Vocal Cord. White dotted line denotes the anterior neck soft tissue thickness at the level of the vocal cords (ANS-VC).

Pinto J et al. measured the amount of soft tissue between the skin and epiglottis (distance from skin to epiglottis, DSE) in a sample of 74 patients and related this index to the presence of difficult laryngoscopy (Fig. 7) [28]. For a DSE cut-off of 27.5 mm, the authors obtained unremarkable statistical parameters (PPV of 33% and DOR of 13), although the parameters improved significantly by combining DSE with MMT (PPV and DOR of 71% and 18, respectively). Yao W et al. used the tongue thickness measurement to predict a difficult laryngoscopy or intubation in 2254 patients [29]. Despite combining this ultrasound index with the thyromental distance, the predictive capacity was very poor (PPV of 27% and DOR of 7.2). Among the parameters that do not measure soft tissue thickness, there are those of the study by Andruszkiewicz et al. [30], which employed the hyomental distance in extension (HMDE) as the predictive index for difficult laryngoscopy in a sample of 199 patients. Thus, an HMDE value of less than 4.28 cm presented a PPV of 64% and a DOR of 73. Lastly, the study by Hui CM et al. [31] employed the non-visualisation of the hyoid bone in the ultrasonography as a predictor of difficult laryngoscopy in 110 patients. The authors performed ultrasounds of the floor of the mouth using a sublingual probe, resulting in a PPV of 71% and a DOR of 76.

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Fig. (7). Ultrasound measurement of the distance from skin to epiglottis (DSE). Three measurements (central axis, left and right extremities of the epiglottis) were taken and averaged.

Therefore, it can be concluded that there is currently no ultrasound index that improves the typical clinical tests in a clinically significant manner. Nevertheless, combining ultrasonography with classical tests does improve the capacity to predict a potential DA. CONCLUSION - Radiology (CT, X-ray) is a promising technique that provides a good comprehensive and accurate assessment of the airway, allowing assessment for diagnosis and exclusion of management difficulties. - The search for perfect radiological parameters to predict Difficult Airway is still on. - Basic knowledge of radiology would reduce morbidity and mortality arising out of difficulties in airway management. - Whenever possible, imaging done for other purposes, for example, for surgical, would be used to formulate effective airway management plans. CONSENT FOR PUBLICATION Not applicable.

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CONFLICT OF INTEREST The authors confirm that the contents of this chapter have no conflict of interest. ACKNOWLEDGEMENT Declared none. REFERENCES [1]

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and intervention in airway management: from the mouth to the lungs and pleurae. Insights Imaging 2014; 5(2): 253-79. [http://dx.doi.org/10.1007/s13244-014-0309-5] [PMID: 24519789] [12]

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Ezri T, Gewürtz G, Sessler DI, et al. Prediction of difficult laryngoscopy in obese patients by ultrasound quantification of anterior neck soft tissue. Anaesthesia 2003; 58(11): 1111-4. [http://dx.doi.org/10.1046/j.1365-2044.2003.03412.x] [PMID: 14616599]

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Reddy PB, Punetha P, Chalam KS. Ultrasonography - A viable tool for airway assessment. Indian J Anaesth 2016; 60(11): 807-13. [http://dx.doi.org/10.4103/0019-5049.193660] [PMID: 27942053]

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Pinto J, Cordeiro L, Pereira C, Gama R, Fernandes HL, Assunção J. Predicting difficult laryngoscopy using ultrasound measurement of distance from skin to epiglottis. J Crit Care 2016; 33: 26-31. [http://dx.doi.org/10.1016/j.jcrc.2016.01.029] [PMID: 26948251]

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Hui CM, Tsui BC. Sublingual ultrasound as an assessment method for predicting difficult intubation: a pilot study. Anaesthesia 2014; 69(4): 314-9. [http://dx.doi.org/10.1111/anae.12598] [PMID: 24641637]

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CHAPTER 2

An Update on Ultrasonography as a Tool for Airway Management Miguel Ángel Fernández Vaquero*, 1, Maria Aliaño Piña1, Maria Aymerich De Franceschi1 and Monir Kabiri Sacramento2 Department of Anesthesiology and Intensive Care, Clínica Universidad de Navarra, Madrid, Spain 2 Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Infanta Leonor, Madrid, Spain 1

Abstract: Because inadequate airway management continues to be an important contributor to serious complications, ultrasound is an emerging tool that has many obvious advantages (safe, fast, repeatable, portable, widely available, and gives dynamic images in real time) that we can use for patient safety. In the upper airway, there are many uses for the ultrasound, for example, oesophageal intubation, adequate placement of the endotracheal tube, selection of the appropriate size of conventional tube and double-lumen tube, adequate placement of supraglottic devices, predictors of difficult airway, predictors of post-extubation stridor risk, prandial status, nerve blocks, or percutaneous tracheostomy.

Keywords: Air-mucosal interface, Airway management, Difficult airway, Cricothyroid Membrane, Hypoechoic, Hyperechoic, Intubation, Intratracheal, Laryngoscopy, Predictors, Pretracheal tissues, Skin-to-epiglottis distance, Skin to hyoid distance, Tracheostomy, Thyrohyoid Membrane, Ultrasonography. INTRODUCTION Ultrasound has become an essential tool for the daily work of any doctor, but in certain specialties such as anaesthesiology, its use has greatly increased the safety offered to patients throughout the perioperative period, either to perform nerve blocks, for vascular access, intraoperative hemodynamic management or any other use that allows increasing quality of care.

Corresponding author Miguel Ángel Fernández Vaquero: Department of Anesthesiology and Intensive Care, Clínica Universidad de Navarra, Madrid, Spain; Tel/Fax: 0034 913 53 19 20; E-mail: [email protected]

*

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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The management of the upper and lower airway and the diagnosis of pathological conditions are essential skills for any doctor especially for Anaesthesiologist, ER physician, Pulmonologist, or Intensive Care physician. Because inadequate airway management continues to be an important contributor to patient mortality and morbidity, any tool that can improve it should be considered as an addition to conventional clinical evaluation. Ultrasound has many obvious advantages (safe, fast, repeatable, portable, widely available, and gives dynamic images in real time). Sonographic studies are operator-dependent and although the identification of basic structures could be acquired with only a few hours of training, more complex studies require a learning curve of months or even years. The highfrequency linear probe (5-14 MHz) is probably the most suitable for the airway because images are of superficial structures (within 0-5 cm below the skin surface) [1]. BASIC CONCEPTS Ultrasound (US) evaluation of the airway is complex in areas that contain air; however, the anterior and lateral walls of the neck are superficial structures and easily assessed by ultrasound. In the upper airway, there are many uses for US (identification of structures, oesophageal intubation, adequate placement of the endotracheal tube, selection of the appropriate size of conventional tube and double-lumen tube, adequate placement of supraglottic devices, predictors of difficult airway, predictors of post-extubation stridor risk, prandial status, nerve blocks, or percutaneous tracheostomy), but this chapter will focus on those that experts think may have a greater application in daily medical work for a better quality of care and greater patient safety, and assess the most recent lines of research. Thus, the main sections of the chapter will be divided into the following: - Anatomical US of the airway. - Systematization of an examination methodology. - Parameters that could define a Difficult Airway (DA). - Location of the Cricothyroid Membrane. - Confirmation of oesophageal vs. tracheal intubation. - Percutaneous Dilatational Tracheostomy (PDT).

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Anatomy of the Airway The anatomical reference to study is the anterior cervical triangle, whose sides are the anterior edges of the sternocleidomastoid muscles, the base is the lower edge of the mandible and the apex is the midline of the jugular notch. The content of this is the hyoid bone, supra and infrahyoid muscles, pharynx, oesophagus, larynx, trachea, thyroid and parathyroid glands, and the thymus (Fig. 1).

Fig. (1). Anterior Cervical Triangle.

The sonographic consistency of each structure must be known. The cartilaginous elements are hypoechoic and homogeneous, the striated muscle and connective tissue are hypoechoic, the fat and glands slightly hyperechoic and homogeneous, the bone is hyperechoic with a posterior acoustic shadow, and finally the hyperechoic and bright air-mucosal interface (Fig. 2).

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Fig. (2). Densities. 1. Cartilage, 2. Striated Muscle, 3. Thyroid gland, 4. Airway.

Systematization of the Echographic Examination Adopting a systematic protocol for the implementation of a standardized examination is important to achieve uniformity and consequent reduction of interprofessional variability. Interpretation of echographic images requires a basic understanding of the physical principles involved in ultrasonography image generation. Besides, transducer selection, orientation, and anatomy of airway relevant to echographic imaging are important to evaluate the anatomy of the airway The patient is placed in the supine position with the head centred and in a sniffing position, using the high-frequency linear probe (5-14 MHz), with a depth of between 3-4 centimeter and the focus at approximately 1 centimeter. A. Transversal Cut A1. Hyoid Level Hyoid bone with an “umbrella shape” is a hyperechoic structure with a posterior acoustic shadow (Fig. 3).

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Fig. (3). Yellow is the Hyoid Bone. Red is the acoustic shadow of the bone.

A2. Thyrohyoid Membrane Level Visualization of the epiglottis with hypoechoic appearance and in its posterior area with a hyperechoic area corresponding to the Air-Mucosal interface. The image that can be obtained is like a “toad mask” (Fig. 4).

Fig. (4). Red is the striated muscle, blue the epiglottis, and Purple is the hyperechoic mucosa-air interfaces.

A3. Thyroid Cartilage Level In young people, the thyroid cartilage is hypoechoic with a “Delta Wing” shape, but in adults, it becomes calcified and prevents us from observing the structures that exist behind it. This is the most appropriate window to assess the vocal cords and their movement, they have a triangular shape and in the deepest area the arytenoids can be observed (Fig. 5).

Fig. (5). Orange is the striated muscle, green is the thyroid cartilage and Purple is the vocal chords.

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A4. Cricoid Cartilage Level It has an “inverted U” shape and it is thicker than the tracheal rings (Fig. 6).

Fig. (6). Red is for striated muscle, Purple is for thyroid gland, Yellow is for cricoid and Blue is for for trachea.

Level Tracheal rings: Inverted U shape (Fig. 7).

Fig. (7). Red striated muscle, purple Thyroid Gland, yellow Tracheal Ring, blue Trachea.

B. Longitudinal Cut B1. Cricoid Cartilage and Tracheal Rings Typical image in pearl necklace (hypoechoic), the last one of a larger size that corresponds to the cricoid cartilage (Fig. 8).

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Fig. (8). Yellow is for cricoid and tracheal rings.

B2. Thyroid and Cricoid Cartilages The cricothyroid membrane appears as a hyperechoic band that joins the thyroid cartilage and cricoid cartilage (hypoechoic), it could be measured and marked (Fig. 9).

Fig. (9). Yellow is for thyroid and cricoid cartilages, and Green is for cricothyroid membrane.

Parameters that could Define a Difficult Airway The inadequate management of the airway is one of the major causes of morbidity and mortality in the hospital and outpatient area, therefore good management of it can prevent many complications. Unfortunately, most of the clinical parameters that should allow us to assess a potential difficult airway, do not always lead us to an adequate prediction, that is why US is used as an emerging tool in many fields, is also gathering strength in this search for a definitive predictor parameter. The growing academic interest in the use of US to look for predictors of difficult airway is centred mainly on measurements at the level of pretracheal tissues. Different studies at different anatomical levels allow us to measure distances that are being evaluated to study their statistical significance. The greatest limitation of these studies is the disparity of the fat distribution that exists between different ethnic groups and sexes, and the lack of standardization method in patient´s intubation conditions.

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In 2003, some authors started to evaluate the pretracheal tissues, with measurements at the level of the vocal cords looking for a parameter to predict a possible DA [2], although unfortunately these values were tried to reproduce years later by other authors concluding that the difference of fat distribution between sexes and ethnic groups limited this possibility [3]. Later in 2011, the measurements of the pretracheal tissues were made in several ultrasound windows, among them the most important are at the level of hyoid, thyrohyoid membrane, vocal cords, thyroid isthmus and finally at the suprasternal level, determining that only the cuts performed at the level of the hyoid [4] (Fig. 10), and the thyrohyoid membrane could be useful as independent predictors of clinical factors to determine a possible DA. For the first time, this study established 15 mm of maximum distance from hyoid bone to skin and 28 mm in the Thyrohyoid membrane window as critical cut-off points for DA.

Fig. (10). Distance from skin to hyoid bone.

Currently, the largest line of research established is around these two windows. In skin to epiglottis distance (DSE) (Fig. 11), the thyrohyoid membrane window, a cut-off point of 27.5 mm was established with an estimated accuracy of 74.3% (sensitivity 64.7% and specificity 77.1%), increasing it to 85.1% when the Mallampati scale was also used and a degree greater than or equal to 3 was obtained [5].

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The DSE is therefore, a good predictor of a possible DA, with a high sensitivity and a high negative predictive value, also considering that if the ultrasound study is added the Mallampati scale increases its value and in patients with a Mallampati score greater or equal to 3 the critical point can be reduced to 26 mm [6].

Fig. (11). Distance from skin to epiglottis.

In conclusion, ultrasound windows at the level of Hyoid and thyroid membrane have been assessed as independent predictors of DA because they are statistically significant in conducted studies [7]. Therefore, the research lines to determine the future DA prediction parameters should continue in these lines. Location of the Cricothyroid Membrane It has been shown that even in expert hands, only 3 out of 10 specialists are able to locate the cricothyroid membrane with only anatomical references. The tracheal structures can be identified by ultrasonography, even when they are not identifiable by palpation, therefore before the possibility of complications in the management of the airway arises, the location of the cricothyroid membrane can convey in a certain degree of reassurance for medical professionals [8]. Following a standardized systematic exploration allows the non-expert hands to locate the Cricothyroid Membrane in less than 1 minute [1] (Fig. 12).

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Fig. (12). Systematic exploration of the cricothyroid membrane.

- Step 1: The patient must be in the supine position and the operator is seated on the right bedside of the patient. - Step 2: The linear transducer must be placed transversely on the neck just above the suprasternal notch. In this cross-section, the trachea is observed in the midline. - Step 3: The transducer must be moved to the right side of the patient until the tracheal midline appears at the right edge of the ultrasound screen. - Step 4: Keeping the right edge in the trachea midline, the left end of the transducer rotates in the sagittal plane 90° counter-clockwise, which results in a longitudinal sweep of the midline of the trachea. In this section, hypoechoic images can be seen as a “string of pearls” that can even be counted and at the end one larger, more superficial and more rounded in the form of a “bean” in cephalic position (corresponding to the tracheal rings and the cricoid cartilage, respectively).

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- Step 5: To locate the cricothyroid membrane these steps must be followed by the cephalic advance of the probe. The tissue that appears at the end of the cricoid is the beginning of the membrane, and at the other end of the membrane the lower portion of the thyroid cartilage can be seen. In this section, the image can be frozen, and the membrane measured. - Step 6: To mark the membrane, a Tuohy needle or any metallic guide of similar thickness can be used. The needle is placed between the skin and the probe, resulting in a hyperechoic image that shows a posterior acoustic shadow. The transducer will move until it is placed on the upper edge of the cricoid cartilage. Once located, the probe can be removed, leaving the needle just on top of the membrane. A marker can be used to mark it. Confirmation of Oesophageal vs. Endotracheal Intubation Ensuring the airway in patients who are going to receive general anaesthesia is very important to provide adequate ventilation and to avoid possible complications that may arise from the failure of an unsuccessful management, therefore anaesthetist can use ultrasound as another tool for the confirmation of intubation, being of special interest in situations where do not have capnography, where auscultation is complex (noisy environments) or in patients with low cardiac output. In expert hands, ultrasound is as quick as auscultation and faster than the auscultation-capnography combination. The confirmation of the orotracheal intubation can be done, at the cricothyroid membrane or suprasternal level, evaluating it: 1. Directly: in real time during the intubation, seeing the tube pass at the level of the different possible sonographic windows (Cricothyroid membrane or suprasternal level). 2. Indirectly: a. Probe placement to observe the pleural sliding, which would also allow us to diagnose selective intubation. b. Movements at the diaphragm level. Directly At the level of the cricothyroid membrane, the following signs have been described [9]:

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1.a. “Snow storm sign” or “flutter sign” is the dynamic phase of the introduction of the endotracheal tube at the level of the vocal cords that previously have a specific triangular shape and later become round. It is observed in 48% of cases. 1.b. “Bullet Sign”, when the tube is inside the trachea and the triangular aspect of the vocal cords is lost, it is observed around 89%. The specificity and sensitivity of both signs together is around 98%. At the suprasternal level, the TRUE PROTOCOL (Tracheal Rapid Ultrasound Exam) has been described, in which the ultrasound probe is placed 1 centimetre above the sternal notch, observing the trachea and trying to locate the oesophagus (the patient can be requested to swallow) (Fig. 13). Maintaining it at this level, a second operator performs the intubation, being able to distinguish in this sonographic section if an oesophageal (Fig. 14). or tracheal intubation is performed [10]. Although capnography still remains as the Gold Standard for correct orotracheal intubation, this methodology would allow us also to assess adequate intubation in patients before being ventilated.

Fig. (13). Orange arrow: oesophagus swallowing.

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Fig. (14). White arrow: oesophageal intubation.

Indirectly Anaesthetist can find a bilateral lung sliding in B mode (Fig. 15) to determine that there is no selective intubation and in M mode it can see the “beach sign”. Although it can be considered the diaphragmatic variability that occurs when starting the ventilation [11].

Fig. (15). Lung sliding.

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Percutaneous Dilatational Tracheostomy Is one of the most used method today for the placement of a permanent cannula, since its complication rate is lower than other techniques. The most common complications are bleeding, hypoxia, multiple punctures, or the laceration of the posterior wall of trachea. Real-time ultrasound adds a series of advantages in performing this technique: 1. Location of the trachea even in difficult cases. 2. Visualization of the anterior wall of the trachea and pretracheal tissue. 3. Visualization and location of the blood vessels by Doppler. 5. Measurement of the distance of the skin to the tracheal lumen to determine the length of the puncture cannula that can be needed and avoid perforating the posterior wall [12]. Ultrasonography has been widely compared in the medical literature to other techniques such as anatomical references or fiberoptic bronchoscopy to perform a percutaneous tracheostomy, the most relevant conclusions are the following [13, 14]. ULTRASOUND VS. ANATOMIC REFERENCES 1. Real-time ultrasound significantly improves the success rate in the first attempt and the precision of it. 2. Lower rate of complications with the use of ultrasound than anatomical references. 3. Ultrasound real time guided should be standardized as a gold standard for performing a percutaneous tracheostomy. ULTRASOUND VS. FIBEROPTIC BRONCHOSCOPY 1. The effectiveness of ultrasound-guided puncture is similar to guide by fiberoptic bronchoscopy. 2. The ultrasound guided procedure involves less time than fiberoptic bronchoscopy. 3. The hypoxia episodes observed with the ultrasound technique are much fewer.

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4. Bleeding episodes are similar in both cases. CONCLUSION - Ultrasound presents a large utility in more and more fields of anaesthesiology and, among them, in the management of the airway. - They have multiple applications, but not all can still be recommended routinely. In the future, it will be necessary to select those more practical applications or of more real interest. - Ultrasound is very useful to locate the trachea or the cricothyroid membrane, even when they are not identifiable by palpation or there are anatomical alterations. - It is to be determined if its predictive value to evaluate the airway is sufficiently high as to recommend it routinely. - As a disadvantage, the anaesthetist must highlight the high learning curve. While learning to identify structures and ultrasound basic is not very laborious, identification of distorted anatomy is. - It could increase quality and safety, but more clinical studies will be needed that confirm their practical feasibility. CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that the contents of this chapter have no conflict of interest. ACKNOWLEDGEMENT Declare none. REFERENCES [1]

Kristensen MS, Teoh WH, Graumann O, Laursen CB. Ultrasonography for clinical decision-making and intervention in airway management: from the mouth to the lungs and pleurae. Insights Imaging 2014; 5(2): 253-79. [http://dx.doi.org/10.1007/s13244-014-0309-5] [PMID: 24519789]

[2]

Ezri T, Gewürtz G, Sessler DI, et al. Prediction of difficult laryngoscopy in obese patients by ultrasound quantification of anterior neck soft tissue. Anaesthesia 2003; 58(11): 1111-4. [http://dx.doi.org/10.1046/j.1365-2044.2003.03412.x] [PMID: 14616599]

[3]

Komatsu R, Sengupta P, Wadhwa A, et al. Ultrasound quantification of anterior soft tissue thickness

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fails to predict difficult laryngoscopy in obese patients. Anaesth Intensive Care 2007; 35(1): 32-7. [http://dx.doi.org/10.1177/0310057X0703500104] [PMID: 17323663] [4]

Adhikari S, Zeger W, Schmier C, et al. Pilot study to determine the utility of point-of-care ultrasound in the assessment of difficult laryngoscopy. Acad Emerg Med 2011; 18(7): 754-8. [http://dx.doi.org/10.1111/j.1553-2712.2011.01099.x] [PMID: 21707828]

[5]

Pinto J, Cordeiro L, Pereira C, Gama R, Fernandes HL, Assunção J. Predicting difficult laryngoscopy using ultrasound measurement of distance from skin to epiglottis. J Crit Care 2016; 33: 26-31. [http://dx.doi.org/10.1016/j.jcrc.2016.01.029] [PMID: 26948251]

[6]

Parameswari A, Govind M, Vakamudi M. Correlation between preoperative ultrasonographic airway assessment and laryngoscopic view in adult patients: A prospective study. J Anaesthesiol Clin Pharmacol (Internet] 2017; 33(3): 353. Available from: http://www.joacp.org/text.asp?2017/33/3/353/214297

[7]

Zheng J. Role of anterior neck soft tissue quantifications by ultrasound in predicting difficult laryngoscopy. Med Sci Monit (Internet] 2014; 20: 2343-50. Available from: http://www.medscimonit.com/abstract/index/idArt/891037 [http://dx.doi.org/10.12659/MSM.891037]

[8]

Elliott DSJ, Baker PA, Scott MR, Birch CW, Thompson JMD. Accuracy of surface landmark identification for cannula cricothyroidotomy. Anaesthesia 2010; 65(9): 889-94. [http://dx.doi.org/10.1111/j.1365-2044.2010.06425.x] [PMID: 20645953]

[9]

Carrillo-Esper R, Nava-López JA, Romero-Sierra G, Cáñez-Jiménez C. Evaluación ultrasonográfica de la vía aérea superior. Rev Mex Anestesiol 2014; 37(2): 123-30.

[10]

Chou HC, Tseng WP, Wang CH, et al. Tracheal rapid ultrasound exam (T.R.U.E.) for confirming endotracheal tube placement during emergency intubation. Resuscitation 2011; 82(10): 1279-84. [http://dx.doi.org/10.1016/j.resuscitation.2011.05.016] [PMID: 21684668]

[11]

Weaver B, Lyon M, Blaivas M. Confirmation of endotracheal tube placement after intubation using the ultrasound sliding lung sign. Acad Emerg Med 2006; 13(3): 239-44. [http://dx.doi.org/10.1197/j.aem.2005.08.014] [PMID: 16495415]

[12]

Chacko J, Gagan B, Kumar U, Mundlapudi B. Real-time ultrasound guided percutaneous dilatational tracheostomy with and without bronchoscopic control: an observational study. Minerva Anestesiol 2015; 81(2): 166-74. [PMID: 25057932]

[13]

Rudas M, Seppelt I, Herkes R, Hislop R, Rajbhandari D, Weisbrodt L. Traditional landmark versus ultrasound guided tracheal puncture during percutaneous dilatational tracheostomy in adult intensive care patients: a randomised controlled trial. Crit Care (Internet] 2014; 18(5): 514. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25231604%5Cnhttp://www.pubmedcentral.nih.gov/articlerender .fcgi?artid=PMC4189189 [http://dx.doi.org/10.1186/s13054-014-0514-0]

[14]

Rajajee V, Williamson CA, West BT. Impact of real-time ultrasound guidance on complications of percutaneous dilatational tracheostomy: a propensity score analysis. Crit Care (Internet] 2015; 19: 198. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25925262%5Cnhttp://www.pubmedcentral. nih.gov/articlerender.fcgi?artid=PMC4438345 [http://dx.doi.org/10.1186/s13054-015-0924-7]

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CHAPTER 3

An Update on Preoxygenation, Apneic Oxygenation, and Prevention of Distortion During Airway Management Paloma Muñoz Saldaña1,*, Norma Aracil Escoda1, Elena Sáez Ruiz1, Ana Tirado Errazquin1 and Flores María Rey Tabasco2 Department of Anaesthesiology and Intensive Care, Hospital Universitario Infanta Leonor, Madrid, Spain 2 Department of Anaesthesiology and Intensive Care, Hospital Universitario de Getafe, Madrid, Spain 1

Abstract: General anaesthesia induction leads to an apneic period which may be longer in case of a difficult airway. Apnea interrupts oxygen supply and may lead to hypoxemia. Desaturation is associated with several serious complications, like brain injuries, rhythm disturbances or cardiac arrest. Preoxygenation and apneic oxygenation help to prevent desaturation.

Keywords: Apneic ventilation, Continuous positive airway pressure, Hypoxia, Hyperoxia, Oxygenation, Oxygen therapy, Preoxygenation, Rapid sequence intubation, Tidal volume breathing, Ventilation. INTRODUCTION Oxygen uptake in adults is about 3 ml.kg/min. Anaesthetic induction can lead to a lack of control of O2 intake that can cause life-threatening complications. Through apnea, tissue oxygenation is maintained using oxygen reserve and continuous O2 administration. During an apnea, the available oxygen reserve (mainly in lungs and blood) is about 1-1.5 L. After 3 or 4 minutes, our body will use all this reserve and peripheral oxygen saturation (SpO2) will decrease [1]. The goal of preoxygenation is to obtain the highest possible oxygen saturation at the time that the residual capacity of the lungs and the bloodstream is denitroge* Corresponding author Paloma Muñoz Saldaña: Department of Anaesthesiology and Intensive Care, Hospital Universitario Infanta Leonor, Madrid, Spain; Tel/Fax: 0034 911 91 80 00; E-mail: [email protected]

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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nated. There are several methods to accomplish this end goal. The variables that contribute to successful preoxygenation include: duration of actions, patient position, comorbidities, and the source of oxygen. The techniques of apnea oxygenation can extend the safe time of apnea, assisting the airway management. PATHOPHYSIOLOGY OF OXYGENATION During anaesthesia, oxygenation depends on alveolar ventilation, distribution of ventilation/perfusion ratio and O2 consumption (VO2). Oxygen reserves: the body´s oxygen reserves are mainly situated in lungs, plasma and haemoglobin. This reserve increases approximately three times when breathing pure O2. Oxygen consumption: in healthy awake subjects is about 300 ml per minute, falling in the elderly about 15%. In an anesthetized patient, oxygen consumption remains rather constant at 250 mL per minute. After ventilation with ambient air, oxygen reserves allow a maximum of 3 minutes of apnea without a serious impact on SpO2. This time can be doubled by correctly performed preoxygenation. The time that apnea is tolerated also decreases if the O2 reserves are low due to reduced functional residual capacity, low arterial oxygenation and/or high oxygen consumption. The objective of preoxygenation is to maintain haemoglobin saturation despite continuous oxygen consumption during apnea. Arterial desaturation during induction and intubation: before upper airway control, desaturation occurs when the O2 reserves are insufficient to support the O2 consumption during the apnea period [2]. PREOXYGENATION Preoxygenation should be defined as the time between the onset of denitrogenation until the beginning of mechanical ventilation and, therefore, includes the apneic period. Denitrogenation of the functional residual capacity is 95% complete within 2-3 minutes breathing at a normal tidal volume form a circle anaesthesia system using an oxygen flow of 5 l/min [3].

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Preoxygenation is an important method to increase the patient's oxygen reserve and the duration of safe apnea before intubation. If it is not done, there is an increased risk of desaturation. ASA Task Force on “Management of the Difficult Airway” 2003 publishes the topic of face mask preoxygenation before initiating management of the difficult airway [4]. Preoxygenation before anaesthetic induction is also recommended in patients with low pulmonary residual functional capacity, associated with high oxygen consumption. This category includes new-borns, pregnant women, and patients with morbid obesity. Preoxygenation is also recommended in patients with decreased oxygen administration, including patients with low cardiac output or pulmonary disease, as well as patients with low or abnormal haemoglobin, such as methaemoglobin. Techniques for administering oxygen can be diverse: ● ● ● ● ● ● ● ●

●

●

Tidal volume breathing. Single tidal capacity breathing. One vital capacity breath followed by tidal volume breathing. Four deep (inspiratory capacity) breaths. Eight deep (inspiratory capacity) breaths. Extended deep breathing (12-16 inspiratory capacity breaths). Continuous positive airway pressure (CPAP). Non-invasive bilevel positive airway pressure. There are several preoxygenation methods depending on the oxygen source, the pressure support, the breathing depth and the duration of the technique: Unsupported ventilation: facemask with reservoir, non-rebreather mask (NRB), bag-valve-mask (BVM) connected to a reservoir, facemask connected to an anaesthesia machine with or without positive end-expiratory pressure (PEEP). Set at 15 L/min, a facemask with a reservoir delivers a FiO2 of 60 to 70%. A true NRB mask can deliver near 90% FiO2 at flow rates > 30 L/min. The optimal oxygen source is a tightly sealed face mask connected to an anaesthesia machine that can deliver near 100% FiO2 at flow rates of about 10 L/min. After ensuring that a right FiO2 is supplied, anaesthetist fixes the facemask to the patient´s face and asks him/her to start tidal volume breathing (TVB) until oxygen expired fraction is above 90%. Usually, about 3 minutes are required. In urgent situations with cooperative patients, the time to achieve adequate preoxygenation can be decreased asking the patient to perform 8 vital capacity breathes (VCB) in a minute. Non-invasive pressure supported ventilation: is typically reserved for situations in which acceptable oxygen saturations cannot be achieved with spontaneous

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breathing and as high as possible FiO2 alone. Preoxygenation with high flow nasal cannula (HFNC) (Fig. 1): this is a relatively recent development. The proposed advantages of this method include the provision that the cannula may be left in place during laryngoscopy.

Fig. (1). Comfort Flow® High Flow Nasal Cannula Therapy, Teleflex.

Traditionally, preoxygenation and intubation are performed in the supine position. This position is physiologically suboptimal, since it decreases the functional residual capacity (FRC), which decreases the volume of air remaining in the lungs at the end of expiration and accelerates the onset of desaturation during apnea. A growing amount of studies support preoxygenation elevating the head by 20°. For patients in whom semi-recumbent positioning is contraindicated (for example traumatic injury), reverse Trendelenburg positioning with the head elevated 15-30° with respect to the feet, provides similar benefits to preoxygenation [1, 5, 6].

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Continuous PEEP improves oxygenation by increasing FRC by reversing pulmonary shunting recruiting poorly ventilated alveoli [5]. In critical situations, preoxygenation can be improved with high-flow nasal oxygen (Fig. 2). This is a technique introduced as non-invasive ventilatory support for infants and adults in ICUs that anaesthetists are using now in operating rooms. This concept is also named as transnasal humidified rapid insufflation ventilator exchange (with the acronym THRIVE). Humidified oxygen flow of up to 50-70 L/min provides not only a high FiO2 but also seems to have another benefit: ● ● ● ● ● ●

Achieve a high and stable FiO2. Decreased upper airway anatomical dead space. Decreased work of breathing. Warmed and humidified inspired gas. Continuous positive airway pressure (up to 8 cm H2O). Lung recruitment.

Factors that affect the efficacy of preoxygenation include the FiO2, duration of preoxygenation, and the alveolar ventilation/functional residual capacity ratio. Failure to achieve an FiO2 near 1.0 may be due to a leak under the face mask, rebreathing of exhaled gases, and the use of resuscitation bags incapable of delivering high FiO2. Patients with beards, edentulous, elderly with sunken cheeks, wrong size face mask, improper position and/or subjection of the head, and gastric tubes are common factors causing air leak and a lower FiO2. The absence of a normal capnography curve, and a lower than expected end-tidal carbon dioxide concentration (EtCO2) and end-tidal oxygen concentration (EtO2) must alert the anaesthesiologist to the presence of leaks in the anaesthetic circuit. FiO2 can also be influenced by the duration of breathing, technique of breathing, and the level of the fresh gas flow (FGF). SECONDARY EFFECTS OF PREOXYGENATION Oxygen has little cardiovascular effects: it increases systemic vascular resistance and decreases cardiac output and cardiac rate. These are minor changes but pregnant women can jeopardize placental flow due to increased thoracic pressure. Increasing PaO2, preoxygenation can lead to a decrease in PaCO2 when using speed techniques, thus reducing brain flow. Preoxygenation leads to micro-atelectasis. High FiO2 is not the only mechanism

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responsible. This micro atelectasis are reversible by application of an alveolar recruitment manoeuvre and they can be prevented by the addition of a PEEP of 10 cm H2O [1, 2].

Fig. (2). Optiflow system®, Fisher & Paykel.

APNEIC OXYGENATION Healthy apneic patients move about 250 mL/min of oxygen from the alveoli to the bloodstream. Contrariwise, just 8-20 mL of carbon dioxide (CO2) moves into the

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alveoli during apnea, creating a pressure in the alveoli to become slightly subatmospheric, generating a mass flow from the upper airway to alveoli via diffusion [5]. This is how supplemental oxygen during apnea provides oxygenrich mixture in the pharynx and may improve arterial oxygen saturation and increases safe apnea time [5, 7]. The extent of delay arterial oxyhaemoglobin desaturation during apnea depends on the efficacy of preoxygenation, the capacity for O2 loading, and the VO2 [8] Fig. (3).

Fig. (3). Arterial oxyhaemoglobin saturation (SaO2) versus time of apnea in an obese adult, a 10-kg child with low functional residual capacity and high ventilation, and a moderately ill adult compared with a healthy adult. FaO2 indicates fractional alveolar oxygen concentration; VE, expired volume. From classic Benumof et al. [9] (https://bit.ly/2Tm9xBK).

Patients with a decreased capacity for O2 transport (decreased functional residual capacity, PaO2, arterial O2 content, or cardiac output), or those with an increased VO2 develop oxyhaemoglobin desaturation more rapidly during apnea than healthy patients [9].

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There are several methods for apneic oxygenation: buccal oxygen delivery device [10], nasal cannula [5, 11] and high flow nasal cannula [5]. PREOXYGENATION BEFORE EXTUBATION Extubation is a critical time during which an oxygen reserve is needed to prevent adverse outcomes associated with the return of spontaneous ventilation and maintenance of a patent upper airway [12]. Due to the potential for airway and ventilation problems, routine preoxygenation before the reversal of neuromuscular blockade and tracheal extubation has been recommended too [8]. Nevertheless, the administration of 100% oxygen, including before extubation, can contribute to the development of atelectasis as well as other adverse effects of hyperoxemia. For this reason, it can be recommended to seek an end-tidal oxygen concentration of 90% before extubation [13]. CONCLUSION ●

●

● ● ●

● ●

Preoxygenation is a technique well recommended by all anaesthesia societies in their difficult airway management guides. Preoxygenation was initially recommended for rapid-sequence induction of anaesthesia in patients with a full stomach, as well as in patients with predicted difficult airway. Today, the technique is recommended as a routine during induction, as well as during recovery from general anaesthesia. The preoxygenation objective is to increase safe apnea time. There are several methods of preoxygenation. Optimal preoxygenation may be carried out with a tightly sealed face mask connected to an anaesthesia machine that can deliver near 100% FiO2 at flow rates about 10 L/min, with the patient breathing tidal volume during about 3 minutes. Preoxygenation has little secondary effects. Apneic oxygenation may be another way to increase safe apnea time.

CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that the contents of this chapter have no conflict of interest. ACKNOWLEDGEMENTS Declared none.

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REFERENCES [1]

Nimmagadda U, Salem MR, Crystal GJ. Preoxygenation: Physiologic basis, benefits, and potential risks. Anesth Analg 2017; 124(2): 507-17. [http://dx.doi.org/10.1213/ANE.0000000000001589] [PMID: 28099321]

[2]

Bouroche G, Bourgain JL. Preoxygenation and general anesthesia: a review. Minerva Anestesiol 2015; 81(8): 910-20. [PMID: 26044934]

[3]

Hamilton WK, Eastwood DW. A study of denitrogenation with some inhalation anesthetic systems. Anesthesiology 1955; 16(6): 861-7. [http://dx.doi.org/10.1097/00000542-195511000-00004] [PMID: 13268902]

[4]

Practice guidelines for management of difficult airway: An updated report by the American Society of Anaesthesiologists Task force on the management of the difficult Airway. Anaesthesiology 2003; 98: 1269-77.

[5]

Gleason JM, Christian BR, Barton ED. Nasal cannula apneic oxygenation prevents desaturation during endotracheal intubation: An integrative literature review. West J Emerg Med 2018; 19(2): 403-11. [http://dx.doi.org/10.5811/westjem.2017.12.34699] [PMID: 29560073]

[6]

Pourmand A, Robinson C, Dorwart K, O’Connell F. Pre-oxygenation: Implications in emergency airway management. Am J Emerg Med 2017; 35(8): 1177-83. [http://dx.doi.org/10.1016/j.ajem.2017.06.006] [PMID: 28623005]

[7]

Wong DT, Yee AJ, Leong SM, Chung F. The effectiveness of apneic oxygenation during tracheal intubation in various clinical settings: a narrative review. Can J Anaesth 2017; 64(4): 416-27. [http://dx.doi.org/10.1007/s12630-016-0802-z] [PMID: 28050802]

[8]

Baraka AS, Salem MR. Preoxygenation. Benumof and Hagberg’s Airway Management. 3rd ed. Philadelphia, PA: Mosby Elsevier 2012; pp. 657-82.

[9]

Benumof JL, Dagg R, Benumof R. Critical hemoglobin desaturation will occur before return to an unparalyzed state following 1 mg/kg intravenous succinylcholine. Anesthesiology 1997; 87(4): 97982. [http://dx.doi.org/10.1097/00000542-199710000-00034] [PMID: 9357902]

[10]

Heard A, Toner AJ, Evans JR, Aranda Palacios AM, Lauer S. Apneic oxygenation during prolonged laryngoscopy in obese patients: A randomized, controlled trial of buccal RAE tube oxygen administration. Anesth Analg 2017; 124(4): 1162-7. [http://dx.doi.org/10.1213/ANE.0000000000001564] [PMID: 27655276]

[11]

Brown DJ, Carroll SM, April MD. Face mask leak with nasal cannula during noninvasive positive pressure ventilation: A randomized crossover trial. Am J Emerg Med 2018; 36(6): 942-8. [http://dx.doi.org/10.1016/j.ajem.2017.10.055] [PMID: 29208322]

[12]

Ortega R, Connor C, Rodriguez G. Endotracheal extubation. N Engl J Med 2014; 370(13): 1267-8. [PMID: 24670181]

[13]

Higgs A, Mitchell V, Dravid R, Patel A, Popat M. Pre-oxygenation before extubation. Anaesthesia 2015; 70(8): 1007-8. [http://dx.doi.org/10.1111/anae.13171] [PMID: 26152265]

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CHAPTER 4

Supraglottic Airway Devices Update María Luisa Mariscal Flores1,*, Rocío Castellanos González1, María Jesús Jiménez Garcia1, Sonia Martín Ventura1 and Claudia Palacios Muñoz1 Department of Anesthesiology and Intensive Care, Hospital Universitario de Getafe, Madrid, Spain 1

Abstract: Difficult Airway Devices (DAD) are instruments used in difficult airway management, with or without intubation. The characteristics of an “ideal” airway device are adequate contact with the upper airway that allows an adequate ventilation, easy insertion for beginners, with short learning curve, minimum risk of aspiration, effective sealing of the upper airway which allows ventilation with positive pressure, no distortion of the pharyngeal anatomy by the pressure cuff or the shape of the device, low morbidity, and good quality. Supraglottic Airway Devices (SAD) are those devices that are placed above the glottis with the objective of ventilating patients, transporting anesthetic gases and oxygen. However, some of these devices can also be located below the glottis, so that some groups now call them Extraglottic Devices (DE). In the last years of the 20th century, many SADs were introduced, and currently, there are at least 20 types of non-disposable and disposable laryngeal masks.

Keywords: Airway device, Difficult Airway, Difficult Airway Society algorithm, Endotracheal tube, ILMA, Laryngeal mask airway, Supraglottic airway devices, SAD, Second generation supraglottic airway devices. INTRODUCTION The classic laryngeal mask (cLMA) designed by Brain in 1981 was the first Supraglottic Airway Device (SAD) introduced into clinical practice in 1988. Several modifications of the original design led to improved types of laryngeal masks. The acronym LMA (but not the term laryngeal mask airway) is a trademark of the company that designed the cLMA and it will only be used in this chapter to indicate the laryngeal masks of this brand, the rest will be called Laryngeal Masks (LM) and are variations of the first one. Most of them have been modified several times since their introduction, so every modification should be carefully evaluated before being approved. Supraglottic devices are rated as class I devices by the FDA (Food and Drugs Administration) since 1996, which means Corresponding author María Luisa Mariscal Flores: Department of Anesthesiology and Intensive Care, Hospital Universitario de Getafe, Madrid, Spain; Tel: 0034 916 83 93 60; E-mail: [email protected]

*

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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that their efficacy and security no longer have to be submitted to the DA when new ones were registered. SADs are in constant evolution, the ideal device has not been developed yet and all of them have their strengths and weaknesses, so the clinician must select the SAD to use in each situation and in each patient. There is an increasing number of different SADs. This chapter will address mostly LMA-type SADs, and in the end, we will make a brief mention of other SADs like the Combitube and laryngeal tube. CLASSIFICATION OF SADS Current classifications of SADs are confusing. There should be an international consensus for this classification, based on the function and safety of the device. Once the published classifications were reviewed, the authors found that the most didactic and simple one was Timmermann’s in 2011 [1], in which devices are classified as: ● ●

●

●

●

First generation SADs, simple airway tubes, such as the cLMA. Second-generation SADs [2], which incorporate features designed to improve safety and protect against aspiration including a gastric tube and provide a better seal, such as the LM Proseal. Intubation SADs, which allow intubation through the device, such as the Intubation Laryngeal Mask (ILMA) Fastrach. Esophageal blockers, which were designed initially for the management of outpatient and emergent airways, such as the Combitube or laryngeal tube. Third generation SADs; this is a controversial term, currently being used without definition, which implies improvement and superiority of the new SAD, or used for self-pressure devices (the LMs that maintain their own pressure), like the Mask Baska LM and Air-Q SP (self-pressure) LM.

Lindsay et al. [3] reviewed the different published classifications from the anatomic-mechanic point of view. Brimacombe’s classification (2004) is based on the presence or absence of sleeve, on the route of insertion and the anatomic location of the distal portion. Miller’s (2004) is based on the mechanism of sealing, proposing a subdivision as disposable or reusable or if they protect from aspiration or not. Hernandez (2012) also published a classification based on the design of the sleeve. Cook and Michalek (2014) described another classification based on the type of sealing (pharyngeal or at the base of the tongue) and introduced the third generation SAD concept.

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LARYNGEAL MASKS AIRWAY (LMA) In this chapter, the term LMA will be used to denote those devices designed by Brain, because this is the first laryngeal mask. We will detail the most interesting aspects of this device. For a more in-depth study, please refer to two books published in 2017 [3, 4] (Fig. 1).

Fig. (1). Laryngeal masks.

Types Classic Laryngeal Mask (cLMA) The classical LMA is a device used for airway management, which occupies the space between the face mask and the endotracheal tube. It was designed by Brain in 1981 and accepted by the FDA as a substitute for the face mask in elective anesthesia in 1991. It consists of a small bowl designed to hold in the hypopharynx with an anterior opening located at the entrance of the glottis, which fitted with some retention bars, that prevent airway occlusion by the epiglottis. The edge of the mask consists of an inflatable silicone sleeve that sits in the hypopharyngeal area.

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Flexible Laryngeal Mask (fLMA) The flexible or reinforced laryngeal mask is similar to the classic LM, with a silicone airway tube fitted with an interior metallic reinforcement, to prevent it from obstruction when twisted. Laryngeal Mask Proseal (PLMA) This 2001 design is intended to improve the protection of the airway against aspiration and malposition frequently occurring with the cLM. It is an open bowl design, without bands, characterized by a second sleeve and a second pipe parallel to the airway tube. The second tube runs along the inside of the bowl to open at the tip of the LM. This opening should reach the upper esophageal sphincter, establishing continuity between the digestive tract and the outside [5]. Mask LMA (MLF or ILMA) Intubation Laryngeal Fastrach This is an advanced LMA, designed by Brain in 1990 to facilitate tracheal intubation, which can be inserted with one hand in any position, without moving the head and neck from a neutral position (Fig. 2). The airway tube is rigid, anatomically curved and fitted with a metallic standard 15 mm connector; it is wide, allowing the passage of a tube more than 8mm. The tube is attached to a rigid handle for easier insertion with one hand. The inflatable cuff can pass through an oral opening of 2 - 2.5 cm. The Epiglottis Elevating Bar (EEB) set at the opening of the mask, raising the epiglottis while the tube passes. This mask is accompanied by a straight, wire-reinforced, silicone endotracheal tube (ETT), provided with depth markers to indicate the distance to the distal tip of the LM airway. It also has a small pilot balloon that fits through the MLF and a specifically designed atraumatic tip. There is also a stabilizer rod that is inserted in the outer end of the ETT to remove the LMF after the intubation, to prevent accidental extubation [6]. Disposable Laryngeal Masks In recent years, new disposable airway devices have appeared, primarily to prevent the transmission of infections. Perhaps in the near future, most devices will be disposable, but currently, these devices have not proven to be as valid and effective as the reusable ones.

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Fig. (2). The intubation laryngeal mask.

We will mention briefly the most popular of these LMs, (designed by Brain); there are other well-known devices, like the i-gel which adapts to the hypopharynx and has a channel for aspiration of gastric content, or the LM Air-Q, disposable, designed for intubation through it, with a shorter shaft which facilitates intubation, and a distal tube to directly guide the ETT to the larynx; the complete description of these LMs exceeds the scope of this chapter.

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Marketed in 2007, the laryngeal mask Supreme (Fig. 3) is a laryngeal mask with gastric access, similar to Proseal, but fitted with epiglottic retention bars and a higher sleeve profile to provide a better seal.

Fig. (3). The LMA Supreme®.

It is disposable, with an angle similar to Fastrach, allowing an easier introduction in any position. In theory, it is a mix of Fastrach, Proseal, and Unique (single-use classical LMA) with disposable material. This is a very good combination because a single mask combines the advantages of the three of them [7, 8]. LMA Protector™ It is a silicone device that incorporates features from previous laryngeal masks. It presents a central tube larger than other models and two lateral drainage pipes. The sleeve incorporates a new system of “traffic light” that allows continuous monitoring of the cuff pressure during use (Fig. 4).

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Fig. (4). The LMA Protector™, Teleflex.

LMA Indications Indications are operator-dependent: The more experienced in LMs use, the wider the indications. According to Lindsay et al, indications are as follows: Basic Indications These devices were initially indicated in ASA I and II patients, for scheduled surgery of short duration and low-risk peripheral surgeries. Indications expanded thanks to a safer design and a better sealing and gastric drainage [9]. Safety in the use of the devices depends on correct positioning, avoidance of hypoventilation due to leakage, avoidance of gastric insufflation, and prevention of regurgitation and aspiration. They are currently used in controlled ventilation in selected patients and surgeries, provided the device is correctly positioned.

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They are used much more in pediatric scheduled surgery [10 - 12]. Indications of Rescue ●

●

●

In CPR, LMs are used, although the endotracheal tube is still the gold standard. Both are considered advanced airway devices, with their advantages and disadvantages, depending on the clinical situation, the experience of the operator, and the characteristics of the patient. More research is needed. In the current ERC and ESA ALS Guidelines, it is clearly stated that SADs can be used by non-proficient rescuers without intubation, and they can even be inserted without interrupting chest compressions [13, 14]. Unforeseen difficult airway management, included in the ASA algorithm of 2003 and 2013, laryngeal masks have two main roles, as a rescue device after face mask ventilation or intubation failure, and secondly as a conduit for intubation.

Advanced Instructions ●

●

●

●

●

●

●

Anticipated difficult airway management: NAP4 (2011) [15] does not recommend it; an alternative plan for the failure of the SAD in these situations is needed. Head and neck surgery, and in those surgeries in which the airway is shared with the surgeon; the flexible laryngeal mask is particularly suitable for these cases. Evaluation of larynx and respiratory tract: as an intermediate device prior to extubation, inserted behind the endotracheal tube and inflated before removing the ETT (Bailey maneuver) [16]. Surgery in prone position [17]: there are few cases in the literature. The safety of this technique is not proved. The selection of patients is very important, and a second-generation device must always be used. Minor laparoscopic surgery (gynecological and abdominal): Currently, there is no evidence that supports this indication, although it is increasingly common. Second-generation devices must be used, in selected patients and with great vigilance. It is very important to empty the stomach before the beginning of surgery. Morbidly obese patients (BMI > 35): the NAP4 reports a greater number of airway complications, particularly when 1st generation devices are used; the 2nd generation devices complication risk is uncertain. A 2013 Cochrane review concludes that the Proseal laryngeal mask is better than ETT in obese patients, improving oxygenation and reduction of postoperative cough [18]. Pregnant women: there is little evidence on their safety because there are few published cases. Their use is controversial today.

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Complications There are generally fewer complications with LMA than with ETT [19]. Aspiration of gastric contents is the most serious complication, and it cannot be completely avoided, although its incidence is similar to endotracheal tube in selected patients (1-5/11000). In case of regurgitation, the following steps should be followed: ●

●

● ●

●

●

Do not remove the LM, because there may be plenty of regurgitated fluid behind; make sure that it is properly positioned and inflated. Disconnect the ventilation circuit temporarily, in order to drain the fluid and move the patient's head downward and laterally. Suction through the LMA and provide 100%oxygen Ventilate the patient manually with low flow and small tidal volume, to avoid fluid passage from the trachea to bronchi. Use a large-caliber fiberscope, to evaluate the tracheobronchial tree and suction the remaining fluid if it is required. If aspiration below the vocal cords is confirmed, consider intubating the patient and follow the proper treatment protocols.

Other complications are: ●

● ● ●

Sore throat and hoarseness, which are more frequent than in endotracheal intubation; it is very important to always use a manometer to measure the pressure of the cuff and never exceed the pressure recommended by the manufacturer [20]. If insertion was difficult, the uvula and pharyngeal pillars can be damaged. Cranial nerve injury [21]. Malposition can appear in 50-80% of cases, such as insertion of the tip of the mask in the glottis, incomplete insertion or tip bending forward or backward. For the detection of these complications, there are different manoeuvres such as the bubble test, yugulum test, insertion of a gastric tube test, or checking that depth marks are in place [22].

Risk Factors for Airway Management with SAD Risk factors described in the literature for the possible difficulty to ventilate with SAD [23] are: ●

Male sex.

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Age > 45 years. Short tiromentonian distance. Limited neck mobility.

OTHER SUPRAGLOTTIC AIRWAY DEVICES Combitube This is a difficult airway device used to ventilate in urgent situations, especially in the pre-hospital setting. It was designed by Dr. Michael Frass in Austria in 1983 in collaboration with Reinhard Frenzer and Dr. Jonas Zahler. It is useful in all circumstances with limited space and lighting (traffic accident, prone position). Insertion is easy for any minimally trained person and can be inserted blindly, although it is easier with a laryngoscope [24, 25] (Fig. 5).

Fig. (5). Combitube.

It is a double lumen latex tube that combines the features of an esophageal obturator airway and a conventional ETT. The esophageal lumen is open at the top (No. 1, longer, blue) and its distal end is closed; there are perforations at

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pharynx level. The tracheal lumen is open in its proximal (No. 2, clear, shorter tube) and distal ends (Figs. 6 and 7).

Fig. (6). Tracheal position (left) and esophageal position (right).

Fig. (7). Malposition.

There are two balloons (latex) that are inflated from the outside: an oropharyngeal balloon with an 85 to 100 ml capacity that is conveniently located proximal to the pharyngeal perforations and is intended to seal the oral and nasal cavity. The tracheoesophageal balloon has a volume of 12 or 15 ml and it is designed to seal

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the trachea or the esophagus. When the Combitube is inserted, it can be placed in the esophagus or in the trachea. If the tube goes into the esophagus, which occurs in more than 95% of the cases, the patient could be ventilated by the holes located in the esophageal tube and the stomach can be suctioned through the tracheal lumen. If the tube enters the trachea, the patient can be ventilated through the tracheal lumen. Easytube Similar to the Combitube, although their balloons are latex-free, and there is a pediatric size [26, 27] (Fig. 8).

Fig. (8). Easytube.

Laryngeal Tube It is a supraglottic airway device used in general anesthesia during spontaneous or positive pressure ventilation. It is a good choice to secure the airway during difficult airway management as an alternative technique to mask ventilation and tracheal intubation (Fig. 9). The laryngeal tube has a single lumen and two balloon cuffs, pharyngeal and esophageal. It was designed by Volker Bertram. The original 1999 prototype had two inflation channels and it has gone through a series of modifications to the current Probe laryngeal tube (PLT 2001), which has a single inflation channel for both balloons and with an internal non-ventilatory channel which allows drainage of the stomach. Further modification of the balloons rendered the laryngeal tube Probe II. There is also a disposable PLT (2004). In the United States, it was marketed under the name “King LT”. The recently appeared Intubation laryngeal tube allows intubation through it, and the Gastro laryngeal tube, which is a

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modification of the PTL II, has a channel for gastroscopic insertion, while it acts as a SAD for the ventilation of the patient) [28].

Fig. (9). Laryngeal tube.

CONCLUSION ●

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●

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●

Supraglottic devices are placed above the glottis, although, sometimes, some of them are also located below the glottis, by what currently some groups call them extraglottic devices. Since 1996, the FDA (Food and Drugs Administration) classified supraglottic devices as class I devices, which means that manufacturers no longer have to submit evidence of efficacy and safety to the FDA when they register new devices. In recent years, new disposable airway devices are appearing, but currently, these devices have not proven to be as valid and effective as the reusable ones. There is not enough data to determine the complications and safety profile for specific SADs. Currently, each anesthesiologist can choose the proper device according to their

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preference. Experts recommend the use of 2nd generation SADs. CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that the contents of this chapter have no conflict of interest. ACKNOWLEDGEMENTS Declared none. REFERENCES [1]

Timmermann A. Supraglottic airways in difficult airway management: Successes, failures, use and misuse. Anaesthesia 2011; 66 (Suppl. 2): 45-56. [http://dx.doi.org/10.1111/j.1365-2044.2011.06934.x] [PMID: 22074079]

[2]

Timmermann A, Bergner UA, Russo SG. Laryngeal mask airway indications: New frontiers for second-generation supraglottic airways. Curr Opin Anaesthesiol 2015; 28(6): 717-26. [http://dx.doi.org/10.1097/ACO.0000000000000262] [PMID: 26539790]

[3]

Helen A. Supragottic Airway Techniques: Laryngeal mask Airways. In: Carin AH, Carlos AA, Michael FA, Eds. Hagberg and Benumof’s Airway Manegement. Eselvier 2017; pp. 328-48.

[4]

Mariscal Flores ML, Martínez Hurtado E, Lucena de Pablo E, Moreno Casanova I. Dispositivos de la Vía Aérea Difícil: Dispositivos supraglóticos.Manual de manejo de la Vía Aérea Difícil. AnestesiaR.org. 2017; pp. 75-108.

[5]

Cook TM, Lee G, Nolan JP. The ProSeal laryngeal mask airway: A review of the literature. Can J Anaesth 2005; 52(7): 739-60. [http://dx.doi.org/10.1007/BF03016565] [PMID: 16103390]

[6]

Gerstein NS, Braude DA, Hung O, Sanders JC, Murphy MF. The Fastrach Intubating Laryngeal Mask Airway: An overview and update. Can J Anaesth 2010; 57(6): 588-601. [http://dx.doi.org/10.1007/s12630-010-9272-x] [PMID: 20112078]

[7]

Verghese C, Ramaswamy B. LMA-Supreme-a new single-use LMA with gastric access: A report on its clinical efficacy. Br J Anaesth 2008; 101(3): 405-10. [http://dx.doi.org/10.1093/bja/aen174] [PMID: 18559351]

[8]

Maitra S, Khanna P, Baidya DK. Comparison of laryngeal mask airway Supreme and laryngeal mask airway Pro-Seal for controlled ventilation during general anaesthesia in adult patients: Systematic review with meta-analysis. Eur J Anaesthesiol 2014; 31(5): 266-73. [http://dx.doi.org/10.1097/01.EJA.0000435015.89651.3d] [PMID: 24145803]

[9]

Timmermann A, Bergner UA, Russo SG. Laryngeal mask airway indications, new frontiers for second generation supraglottics airways. Curr Opin Anesthes 2015; 28: 716-26.

[10]

Kim MS, Oh JT, Min JY, Lee KH, Lee JR. A randomized comparison of the i-gel and Laryingeal mask Airway classic in infants. Anaesthesia 2014; 69: 362-67.

[11]

Ronald S. Litman. Complications of laryngeal masks in children. Big data comes to pediatric anesthesia. Anesthesiology 2014; 119(6): 1239-40.

[12]

Mihara T, Asakura A, Owada G, Yokoi A, Ka K, Goto T. A network meta-analysis of the clinical properties of various types of supraglottic airway device in children. Anaesthesia 2017; 72(10): 1251-

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64. [http://dx.doi.org/10.1111/anae.13970] [PMID: 28737223] [13]

European Resuscitation Council Guidelines for Resuscitation. 2015. https://cprguidelines.eu/.

[14]

American Heart Association Guidelines for CPR & Emergency Cardiovascular Care. https://bit.ly/1LPMvNW.

[15]

Cook TM, Woodall N, Frerk C. Mayor complications of airway management in the UK. Results of The Fourth national Audit Proyect of the Royal College of Anaesthetists and Difficult Airway society. Br J Anaesth 2011; 106(5): 617-31. [http://dx.doi.org/10.1093/bja/aer058] [PMID: 21447488]

[16]

Dob DP, Shannon CN, Bailey PM. Efficacy and safety of the laryngeal mask airway vs Guedel airway following tracheal extubation. Can J Anaesth 1999; 46(2): 179-81. [http://dx.doi.org/10.1007/BF03012554] [PMID: 10084000]

[17]

López AM, Valero R. Use of supraglottic airway devices in patients positioned other than supine. Trends Anaesth Crit Care 2012; 2(2): 65-70. [http://dx.doi.org/10.1016/j.tacc.2012.02.006]

[18]

Nicholson A, Cook TM, Smith AF, Lewis SR, Reed SS. Supraglottic airway devices versus tracheal intubation for airway management during general anaesthesia in obese patients. Cochrane Database Syst Rev 2013; (9): CD010105. [http://dx.doi.org/10.1002/14651858.CD010105.pub2] [PMID: 24014230]

[19]

Yu SH, Beirne OR. Laryngeal mask airways have a lower risk of airway complications compared with endotracheal intubation: A systematic review. J Oral Maxillofac Surg 2010; 68(10): 2359-76. [http://dx.doi.org/10.1016/j.joms.2010.04.017] [PMID: 20674126]

[20]

Bick E, Bailes I, Patel A, Brain AI. Fewer sore throats and a better seal: Why routine manometry for laryngeal mask airways must become the standard of care? Anaesthesia 2014; 69(12): 1304-8. [http://dx.doi.org/10.1111/anae.12902] [PMID: 25303083]

[21]

Thiruvenkatarajan V, Van Wijk RM, Rajbhoj A. Cranial nerve injuries with supraglotic airway devices: a systematic review of published case reports and series. Anaesthesia 2015; 70: 344-59.

[22]

Van Zundert AAJ, Kumar CM, Van Zundert TCRV. Malpositioning of supraglottic airway devices: Preventive and corrective strategies. Br J Anaesth 2016; 116(5): 579-82. [http://dx.doi.org/10.1093/bja/aew104] [PMID: 27106958]

[23]

Saito T, Liu W, Chew ST, Ti LK. Incidence of and risk factors for difficult ventilation via a supraglottic airway device in a population of 14,480 patients from South-East Asia. Anaesthesia 2015; 70(9): 1079-83. [http://dx.doi.org/10.1111/anae.13153] [PMID: 26052860]

[24]

Agro F, Frass M, Benumof JL, Krafft P. Current status of the Combitube: A review of the literature. J Clin Anesth 2002; 14(4): 307-14. [http://dx.doi.org/10.1016/S0952-8180(02)00356-2] [PMID: 12088818]

[25]

Enlund M, Miregard M, Wennmalm K. The Combitube for failed intubation--instructions for use. Acta Anaesthesiol Scand 2001; 45(1): 127-8. [http://dx.doi.org/10.1034/j.1399-6576.2001.450120.x] [PMID: 11152025]

[26]

Lorenz V, Rich JM, Schebesta K, et al. Comparison of the EasyTube and endotracheal tube during general anesthesia in fasted adult patients. J Clin Anesth 2009; 21(5): 341-7. [http://dx.doi.org/10.1016/j.jclinane.2008.09.008] [PMID: 19700284]

[27]

Gaitini L, Yanovsky B, Somri M, et al. Prospective randomized comparison between Easy-Tube and Esophageal Tracheal Combitube during general anesthesia with mechanical ventilation. J Clin Anesth 2011; 23: 475-81. [http://dx.doi.org/10.1016/j.jclinane.2011.01.007] [PMID: 21911194]

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Hagberg C, Bogomolny Y, Gilmore C, Gibson V, Kaitner M, Khurana S. An evaluation of the insertion and function of a new supraglottic airway device, the King LT, during spontaneous ventilation. Anesth Analg 2006; 102(2): 621-5. [http://dx.doi.org/10.1213/01.ane.0000189101.26403.06] [PMID: 16428573]

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CHAPTER 5

Optic Airway Devices Update Eugenio Daniel Martinez-Hurtado1,*, Miriam Sanchez-Merchante2, Pablo Renedo Corcóstegui3, Manuel Granell Gil4 and Guillermo Navarro5 Department of Anaesthesiology and Intensive Care, Hospital Universitario Infanta Leonor, Madrid, Spain 2 Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Fundación Alcorcón, Madrid, Spain 3 Department of Anesthesiology and Critical Care Medicine, OSI Alto Deba, Mondragón, Guipúzcoa, Spain 4 Universidad de Valencia, Médico Jefe de Sección de Anestesiología, CHGUV, Vocal de Torácica (SEDAR) y del ThoracicSubCommittee (EACTA), Valencia, Spain 5 Department of Anesthesiology and Critical Care Medicine, “Hospital de Emergencias Dr. Clemente Álvarez”, Ciudad de Rosario, R. Argentina 1

Abstract: Difficult orotracheal intubation (OTI) represents the main cause of anaesthetic morbidity and mortality. A third of all anaesthesia-related deaths are secondary to the inability to maintain a clear airway to guarantee a correct oxygenation, and nearly two-thirds of problems related to the management of the airway occur during anaesthetic induction.

Keywords: Airway management, Difficult airway, Fiberoptic Bronchoscopy, Intubation, Intratracheal, Laryngoscopy, Macintosh, Oxygenation, Predictors, Videolaryngoscope. INTRODUCTION Achieving safe airway management, oxygenation, and ventilation is a priority in all patients who undergo general anaesthesia. Serious or catastrophic consequences of a failed airway management intervention are: unforeseen admission into a critical care unit, permanent hypoxic neurological damage, emergency or unplanned airway surgery, and death [1]. Difficult orotracheal intubation (OTI) represent the main cause of anaesthetic morbidity and mortality, and it is considered that a third of anaesthesia-related * Corresponding author Eugenio D. Martinez-Hurtado: Department of Anesthesiology and Intensive Care Hospital, Universitario Infanta Leonor, Madrid, Spain; Tel/Fax: 0034 911 91 80 00; E-mail: [email protected]

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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deaths are due to the inability to maintain safe airway to guarantee correct oxygenation [2], and nearly two-thirds of problems related to the management of the airway will occur during anaesthetic induction [3]. Macintosh blade represents a direct laryngoscope (DL) gold standard. OTI with a conventional DL is still considered as the common practice. On the contrary, in difficult airway cases (DA), Fiberoptic Bronchoscopy (FOB) is still the technique of choice for intubation. Many studies claim videolaryngoscope in the induced/asleep or awake patient as a shorter time intubation method, with a success rate and safety profile comparable to FOB [4]. Besides, FOB is fragile and expensive equipment and requires regular maintenance, it is difficult to have it available in emergency situations or emergency pre-hospital and it is required in previous training [5 - 12]. Failure in endotracheal intubation with Macintosh direct laryngoscopy or other technique can occur unexpectedly. Facing difficult tracheal intubation during general anaesthesia is always a cause for concern because multiple intubation attempts increase the morbidity and mortality significantly. Several studies demonstrated increased morbidity when multiple tracheal intubation attempts are made. Therefore, when Difficult Airway is suspected, tracheal intubation in asleep patients after induction should be considered only when intubation is expected to be achieved with a maximum of 3 attempts [13], and that is how it is reflected in every current guideline of the distinct societies. CONCEPT Videolaryngoscopes (VL) allow a view of the entrance of the glottis independent of the line of sight (indirect laryngoscope [IL]), especially those with angled blades [14, 15] (Fig. 1). An image sensor is located in the distal part of the blade and it provides a panoramic view of the glottis, without a need to “align the axes” and avoiding head hyperextension [16]. In daily practice, VLs provide a Cormack-Lehane laryngoscopy (CL) grade 1 or 2 in 99% of cases (1/4 or 2/4 CL). FEATURES VL and other optical devices (OD) have common characteristics [17, 18]: ●

●

●

Technically: Large high-resolution image that improves the view degree of direct laryngoscopy. Procedure: Similar to Macintosh or Miller laryngoscope intubation technique. Some models must be introduced by midline. Teaching: It allows to teach and show multiple views. A student can see the

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result of laryngeal manipulation. The procedure can be stored and displayed multiple times. It facilitates the learning of alternatives to FBO techniques. Research: Images can be stored and shared. User comfort: A more comfortable position, less contact with secretions or blood. Secretions and blood can make the use of a videolaryngoscope difficult or impossible as they can stain the camera. Some models can be used to perform both direct or indirect laryngoscopy, with advantages of video versus classical Macintosh.

Fig. (1). Video line of vision, blind spot and operator’s direct line of vision with C-Mac videolaryngoscope (From: Lawrence, Michal et al. “Trismus and the limits of laryngoscopy.” Anaesthesia 69 12 (2014): 1401-2 [bit.ly/2Ng2OXj]).

Among the characteristics that would define an ideal intubation device, the following should be included: ● ● ● ●

Economic and single-use. Brief learning curve. Good glottis view. Quick orotracheal intubation.

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Suitable for all types of endotracheal tubes (ETT). Allows the administration of O2. Allows the suction. Not producing hemodynamic changes. It can be used with little mouth opening. No need for cervical hyperextension (Fig. 2). It can be used in any patient position. Possibility of connection to monitor for teaching. It can be used in awake patients.

Fig. (2). Cervical manipulation for alignment of the 3 axes. OA: oral axe, PA: pharyngeal axe, LA: laryngeal axe (From: Mendis D, Oates J. The Application of Airtraq (fibreoptic intubation device) to Otolaryngology. Online J Health Allied Scs. 2011;10(2):16).

INDICATIONS In order to ensure a safe airway, oxygenation and ventilation are priorities in all patients who undergo general anaesthesia. When an anaesthetist performs laryngoscopy, the first step is to determine if the glottis structures are visible. If this is not possible, additional measures to achieve an improvement in vision will be needed. Even though there are a variety of laryngoscope blades, all of them have restrictions in design (width, thickness, profile, etc.). This diversity indicates that there is still no optimal design that can achieve a complete exposure to the glottis in all cases. Common indications [19] to all OD would be: ● ● ● ● ● ●

Difficult Airway management. Awake patient intubation. Helps fiberscope. Cervical instability. Obesity. Teaching.

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Rapid Sequence Induction intubation. Intubation with a lot of secretions, blood, in which fiberscope cannot be used (even though they can make difficult the use of a VL / OD as they can stain the camera, as we explained before). Infectious diseases. Hemodynamic alterations and increased intracranial pressure. Nasotracheal intubation. Intubation with the double-lumen tube. Introduction of probe nasogastric tube. Support for ETT change.

Along with the improvement of vision, there will be needed an efficient intubation technique [20]. All these devices allow optimal viewing of the glottis anatomy, but sometimes it is necessary to perform manoeuvres for intubation which may require more complexity than LD because of the difficulty in the orientation of the ETT. Guides and specific stylet have been designed for that purpose. The real difficulty in intubation with videolaryngoscopy is often independent of the glottis view in the screen, contrary to direct laryngoscopy [21]. Therefore, a record system has been suggested that incorporates the difficulty found during the passage of the ETT. It can be integrated by a description of the difficulty encountered (easy, difficult or failed), documentation of the glottis vision obtained (modified CL), and device description [22]. Channelled videolaryngoscopes give the advantage of orienting ETT towards the trachea allowing intubation guided with least manipulation. Thus, it is possible to avoid the trauma on the oro-pharynx-tracheal mucosa, besides greater simplicity of usage that implies greater intubation success and fewer injuries associated with handling. Thereby, these devices can be handled without manipulating the ETT, since intubation is guided by the blade, achieving a greater manoeuvrability. Avoiding oral cavity manipulation secondary to ETT due to intubation performed with the channelled blade guarantees the lack of perforations or injuries on the pharyngeal mucosa. Besides that, limitation of the mouth opening complicates its use. LIMITATIONS [23] Videolaryngoscopes have an important cost limitation that implies above all, limited access in some areas, such as outside the operating room, emergency services, out of hospital services, etc. Devices need to be connected to the mains or batteries, and those who have an external monitor may be “little portable”.

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Because they provide an indirect image, blood, secretions and fogging of the lens obscure or abolish the image. In these critical situations, it is still possible to have a direct glottis view with some of them (with direct blades similar to Macintosh laryngoscope blade). Fogging can be prevented by previously suctioning the pharynx, pre-heating or applying specific solutions to the distal lens if the device does not have a specific anti-fog system (such as Airtraq, GlideScope, King Vision, etc.). Like any other device, VLs need a learning curve [24]. Those who have a nonchannelled direct blade similar to Macintosh blade, need an insertion transglottic device (intubating stylet, Frova, Eschman, Bougie, etc.). It is mandatory to learn the technique since they can lead to injuries of the soft palate during their usage. COMPLICATIONS All these devices allow optimal viewing of the glottis anatomy, but sometimes more complex manoeuvres for intubation are needed because of the difficulty in ETT orientation [25, 26]. Therefore, complications have been described in parallel with clinical uses of these devices as glottis mucosal lacerations, lesions of vocal cords, subluxations of arytenoid and supracarinal´s tears (Fig. 3).

Fig. (3). Perforation of the palate with Glidescope.

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CLASSIFICATION Optical devices have a camcorder that allows the operator to view the glottis indirectly. Its design may vary depending on how the camcorder is available. There are several types of VLs, with different types of blades, interfaces and intubation strategies, as well as different models from the rest of the OD. This indirect vision of the glottis can be obtained in different ways: ●

●

Video miniature camera: digital image is electronically transmitted to a screen in the device (King Vision, Totaltrack), or an external monitor (McGrath MAC, CMAC, Glidescope). Bundle of optical fibres or prisms (Airtraq): transmits the image to the device through a video (Pentax AWS) or lens system (Airtraq).

Pott and col [27], Healy DW and col [28], and Niforopoulou et al. [29] proposed different classifications, and we summarized and modified them in a proposed classification of optical devices that tries to pool together all the varieties according to similar characteristics to each other (Fig. 4): ●

● ● ● ●

Videolaryngoscopes with Rigid blade, either a blade “standard”, similar to the Macintosh DL, or an angled blade. Videolaryngoscopes with a channelled blade to guide the ETT. Fiberoptic stylets. Videofibroscopes. Videolaryngoscopes that allow oxygenation during the intubation manoeuvre.

Videolaryngoscopes with Rigid Blade VL with 'Standard' Rigid Blade All of them present a fundamental characteristic: they can be used as a conventional direct laryngoscope. This reduces, at least theoretically, the learning process required to use them correctly. Another advantage they have in common is the ease with which they visualize glottis structures, which enables them to use any type of ETT, for a longer duration than the fiberscope at a lower cost. The disadvantage is that, although CL usually improves the introduction of ETT, sometimes it is difficult and it requires some practice. Therefore, sometimes ETT should be guided with an intubation stylet (as with the angled blades).

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VL with Angled Rigid Blade Common advantages to all of them are: ease visualization of glottis structures, use of any type of ETT, longer duration than the fiberscope, and lower cost. The disadvantage is that, although CL usually improves, the introduction of ETT is sometimes difficult. The absence of a channel that guides the ETT along with the blade angle obliges to use an intubation stylet at the same angle as the blade to direct the ETT to the entrance of the glottis.

Fig. (4). Weight classification based on Body Mass Index (BMI).

Videolaryngoscopes with Blade with Channel to Guide the Endotracheal Tube These blades have a channel where ETT slides for intubation. As ETT moves into the channel, any modification or movements must be made on the device and not on the tube. The ETT does not require to be trusted with an intubating stylet, and these devices usually improve the CL view. Videolaryngoscopes that Allow the Oxygenation during Intubation Manoeuvre Totaltrack VLM This is the only new device appeared in recent years. The other devices have been widely described and studied over the last two decades, since Jon Jack Berall created the first videolaryngoscope in 1998 (Fig. 5), in books and scientific articles. Therefore, due to its novelty and its unique and specific characteristics, a revision of this device will be carried out.

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Fig. (5). First Videolaryngoscope U.S. patent (5.827.178). 27 Oct 1998.

The Totaltrack® Video Laryngeal Mask (VLM) (Medcomflow, S.A.) was designed by Dr. Pedro Acha, whose previous design was the Airtraq. It could be defined as a 3rd generation disposable Supraglottic Airway Device (SAD) allowing intubation with a direct view and continuous ventilation since the device is introduced into the patient's mouth while adding the possibility of intubation keeping with ventilation; or as a 3rd generation Videolaryngoscope which allows ventilation while performing intubation (Fig. 6). Airway management is usually done with a sequential combination of different devices, with a facemask, SAD, direct laryngoscopes, and videolaryngoscopes being the most commonly utilised, using guides, algorithms, VORTEX approach, etc. The VLM concept can itself integrate several functions that previously mentioned devices do separately. This includes keeping the airway permeable, ventilating/oxygenating, separating the digestive tract from the respiratory tract, and intubating under continuous viewing “without stopping ventilation”. In cases of a failed intubation attempt, VLM can continue optimal ventilation/oxygenation while the operator thinks about the next step of the strategy. VLM can integrate functions that other devices on their own cannot provide to the patient. Initial airway management with VLM is done at the time of inducting general anaesthesia with the insertion of the VLM according to the technique recommended by the manufacturer.

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It begins functioning through “Mask Mode” (MM), with or without the use of neuromuscular blocking agents (NMBA). The ventilation of the patient is started and verified clinically by monitoring the CO2 End-tidal (three consecutive capnography of normal morphology). Then, without interrupting ventilation, the anatomical structures of the larynx are located with the Videotrack by going to the next functional mode known as “Intubation Mode” (IM), and ETT descends towards the tracheal lumen. The reverse process can be followed for extubation.

Fig. (6). Totaltrack® Video Laryngeal Mask (VLM). Images courtesy of Medcomflow.com.

VLM can function sequentially in modes that guarantee safe management of the patient’s airway in various contexts. The “safe apnoea period” is a value estimated in seconds and independently of the population considered. In addition to the technique and device chosen for airway management, it is always a factor of interest and critical concern for anaesthesiologists. The VLM, while having initial

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control of the ventilation and the ability to continue this process, enables operative margins for specifying intubation that other devices cannot provide on their own. The consideration to add neuromuscular blockers in the mask mode or to maintain spontaneous ventilation of the patient is a big advantage in the management of patients where, because of their history, stopping ventilation is a risk. Clinical judgement and experience of the anaesthesiologist will define the right time to use these agents. An additional advantage of VLM is that continuous real-time viewing of the laryngeal structures can be obtained with the integrated anti-fogging system, which facilitates intubation. In the case of an initial failed intubation attempt, intubation can be aided with a bougie guide supplied with the equipment or with a fibre optic device while ventilation/oxygenation is maintained, thus bringing in more options for intubation. It is integrated by a reusable camcorder (Videotrack) and a disposable kit (Totaltrack VLM) (Fig. 7).

Fig. (7). Totaltrack® Video Laryngeal Mask (VLM) Pack. Images courtesy of Medcomflow.com.

The VLM mask component has been designed by considering the desirable elements in modern SADs: ease of insertion, high rate of first attempt insertion

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success, protection against regurgitation events, good peri-laryngeal sealing quality, and low incidence of post-operative period complications. Nevertheless, additional studies are needed to authenticate the quality of the proposed design [30] (Fig. 8).

Fig. (8). Totaltrack® Video Laryngeal Mask (VLM) parts.

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VLM Totaltrack Features ● ●

● ● ● ● ● ● ● ●

●

●

●

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Allows first to ventilate and then intubate, and vice versa. Continuous vision during both manoeuvres with a unique camcorder for this system. Oxygenation with continuously positive pressure during both operations. Allows using ETT standard large size up to 8.5 mm. Allows safe extubation under safe ventilation and a continuous vision. Only takes a person for management. It has a dedicated channel for gastric aspiration. It has a unique suction system for the internal secretions of the mask. An anti-mist system. It can be used in any position on the patient. It is not necessary to hyperextend the neck of the patient. Superficial anaesthesia in the final stage of the surgery to the Exchange mode intubation by the ventilation mode. Management of medications: taking advantage of the 2 modes of use of the VLM Totaltrack, intubation and ventilation can: Make an induction without relaxing the muscle to insert the VLM Totaltrack, airing as a supraglottic. After checking that you can ventilate the patient, muscle relaxants can be applied to be able to intubate the patient.

VLM Totaltrack Contraindications ●

● ●

Interdental opening greater than the minimum recommended: #3 size 17 mm and the size #4 / #5 19 mm. Bleeding in the oral or laryngeal cavity, preventing a proper vision. Allergy to the medical quality silicone or PVC medical quality (compounds of the VLM Totaltrack).

VLM Totaltrack Management Technique VLM is a device that can allow tracheal intubation under safe conditions and uninterrupted ventilation, oxygenation, and delivery of anaesthetic gas. In addition, with the Videotrack, all the management processes are performed under real-time continuous viewing. These characteristics make VLM a useful device under various airway scenarios. Its ability to maintain ventilation is especially interesting in difficult cases because it allows the operator to have time to think about the strategy to follow (Fig. 9). VLM is a device that can allow for tracheal extubation under safe conditions and

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uninterrupted ventilation, and oxygenation as well (Fig. 10) [31].

Fig. (9). Insertion of the Totaltrack® Video Laryngeal Mask (VLM) in the mouth in the midline.

Fig. (10) cont.....

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Fig. (10). Safe extubation with Totaltrack® Video Laryngeal Mask (VLM) [31].

VLM Totaltrack Contraindications and Warnings The contraindications for the use of VLM Totaltrack are the same as that for SADs, and can vary depending on the clinical contexts analysed. There is possibly no other factor that would interfere with or contraindicate its use when recovering oxygenation in airway rescue cases (hypoxemia or serious hypoxemia not managed by other devices). Nevertheless, as in all SADs, the risks with VLM Totaltrack must be weighed against the benefits of its indication. Its use has frequently been contraindicated in patients with more than one defined risk factor of regurgitation, vomiting and posterior bronchial inhalation of gastric content, since aspiration of gastric content is considered the most serious complication of its use. CONCLUSION ●

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There is no scientific evidence to indicate the superiority of any optical device over the rest. Inexperience is the risk factor leading to a higher rate of failures. Skill is achieved with daily practice. The learning curve must begin with CL 1 cases and planned management of theoretically easy airway patients. With greater skill, its use will be more effective. Greater numbers of studies are needed to make definitive conclusions about the optical device. The authors should carry out randomized clinical trials.

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CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST None declared. No company funded this chapter. Only some images are courtesy of Medcomflow.com. ACKNOWLEDGEMENT Declared none. REFERENCES [1]

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Abramson SI, Holmes AA, Hagberg CA. Awake insertion of the Bonfils Retromolar Intubation Fiberscope in five patients with anticipated difficult airways. Anesth Analg 2008; 106(4): 1215-7. [http://dx.doi.org/10.1213/ane.0b013e318167cc7c] [PMID: 18349195]

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Hindman BJ, Fontes RB, From RP, et al. Intubation biomechanics: laryngoscope force and cervical spine motion during intubation in cadavers—effect of severe distractive-flexion injury on C3–4 motion. J Neurosurg Spine 2016; (May): 27.

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Wallace CD, Foulds LT, McLeod GA, Younger RA, McGuire BE. A comparison of the ease of tracheal intubation using a McGrath MAC(®) laryngoscope and a standard Macintosh laryngoscope. Anaesthesia 2015; 70(11): 1281-5. [http://dx.doi.org/10.1111/anae.13209] [PMID: 26336853]

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Hurford WE. The video revolution: a new view of laryngoscopy. Respir Care 2010; 55(8): 1036-45. [PMID: 20667151]

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Akihisa Y, Maruyama K, Koyama Y, Yamada R, Ogura A, Andoh T. Comparison of intubation performance between the King Vision and Macintosh laryngoscopes in novice personnel: a randomized, crossover manikin study. Anesth 2014; 28: 51. [http://dx.doi.org/10.1007/s00540-013-1666-9]

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Najafi A, Imani F, Makarem J, et al. Postoperative sore throat after laryngoscopy with macintosh or glide scope video laryngoscope blade in normal airway patients. Anesth Pain Med 2014; 4(1)e15136. [http://dx.doi.org/10.5812/aapm.15136] [PMID: 24660157]

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Niforopoulou P, Pantazopoulos I, Demestiha T, Koudouna E, Xanthos T. Video-laryngoscopes in the adult airway management: a topical review of the literature. Acta Anaesthesiol Scand 2010; 54(9): 1050-61. [http://dx.doi.org/10.1111/j.1399-6576.2010.02285.x] [PMID: 20887406]

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Hurtado EM, Merchante MS. Safe Extubation with Totaltrack® Video Laryngeal Mask. Acad Anesthesiol Int 2016; 1(1): 3-5.bit.ly/2NbkH9A. [http://dx.doi.org/10.21276/aan.2016.1.1.2]

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CHAPTER 6

Tracheal Tube Introducers, Stylets, Exchange Catheters, and Staged Extubation Sets in Airway Management María Jesús Galán Arévalo1,*, Javier Béjar García1, Alicia Ruiz Escobar2 and Enrique Platas Gil3 Department of Anesthesiology and Critical Care Medicine, Clínica CEMTRO, Madrid, Spain Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Infanta Leonor, Madrid, Spain 3 Servicio de Medicina Intensiva, Hospital Universitario de la Princesa, Madrid, Spain 1 2

Abstract: Introducers and stylets are two very useful devices for overcoming difficulties in airway management. In fact, they are the first option in many difficult airway algorithms. The design and use of these tools have evolved over the years, and several introducers and stylets are currently available on the market, with different indications and applications in daily clinical practice. Anaesthetists should be familiar with the different devices, characteristics and indications in order to ensure correct application in each situation [1].

Keywords: Bonfils, Bougies, Criteria for extubation, Difficult intubation, Exchange catheters, Extubation algorithm, Extubation complications, Extubation failure, Introducers, Intubation, Intubation aids, Laryngotracheal damage, Laryngospasm, Lighted stylets, Optical stylets, Paralysis of vocal cords, Periglottic damage, Pulmonary edema, Staged extubation sets, Stylets, Tracheal extubation. TRACHEAL TUBE INTRODUCERS AND STYLETS Difficult airway management may entail serious complications [2 - 4]. When the glottis cannot be seen with direct laryngoscopy, two options are available: the first involves shaping and directing the tube using a stylet, and the second involves

* Corresponding author María Jesús Galán Arévalo: Department of Anesthesiology and Intensive Care, Clínica CEMTRO, Madrid, Spain; Tel/fax: 0034 917 35 57 57; E-mail: [email protected]

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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blindly placing an introducer, over which the endotracheal tube can be inserted. Since these devices are associated with a high success rate, their use is recommended at an early stage in many cases [5, 6]. Furthermore, they can easily be combined with more recently developed devices such as videolaryngoscopes [7 - 9]. Endotracheal Tube Introducer The classic endotracheal tube introducer is known by many names but is most commonly called a bougie. This device consists of a 60 cm stylet, the distal tip of which is angled at 30 degrees. This means the tip can be aimed anteriorly and passed under the epiglottis and through the glottis, even if the vocal cords are not visible. Broadly speaking, three main types of introducer are available, with similar dimensions and uses: The Eschmann introducer (designed to be sterilised and reused; commonly known as a bougie), the SunMed Flex Guide (single-use), and the Frova (single-use and fenestrated to enable oxygenation, including an adaptor for this purpose) (Fig. 1). All three devices have a similar per-use cost: The Eschmann, though more expensive, can be used several times.

Fig. (1). Frova Intubating Introducer, Cook medical.

●

●

Indications: Introducers are particularly useful when the epiglottis is visible but not the vocal cords (Cormack-Lehane grade 3) [10]. They can be combined with other devices besides the traditional laryngoscope, such as videolaryngoscopes. Contraindications: Pimarily if there is a suspicion of laryngeal or tracheal injury since introducers can aggravate these lesions or migrate to adjacent structures outside the respiratory tract. These devices are less effective when

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neither the glottis or epiglottis is visible (Cormack-Lehane grade 4). Technique: Lubricant may be applied so that the tube glides more easily over the introducer, depending on the difference in calibre between the two. Ideally, the introducer and tube should be of a similar size, but depending on the degree of difficulty of intubation, a smaller tube may be preferable.

The next step is identifying the epiglottis, with or without external manoeuvres or other placement techniques. The introducer is then advanced towards the trachea, with the tip in the midline, aimed anteriorly and below the epiglottis. To be able to see the anterior tracheal rings (one sign confirming the introducer is correctly positioned) [11], it is recommended not to twist the introducer. Nor should it be inserted with force, as this may result in the rare but reported complications of bleeding or perforation [12]. Another sign confirming the tracheal placement of the introducer is the resistance felt between 24 cm and 40 cm past the teeth when it reaches a smaller airway. If the introducer enters the oesophagus, it can be easily advanced towards the stomach, even past the 40 cm mark. The endotracheal tube is inserted by sliding it over the introducer. An assistant is normally needed to preload the endotracheal tube over the proximal end of the introducer. The laryngoscope must be kept in place during the whole process. The introducer is removed when the endotracheal tube has advanced far enough. The correct placement of the latter will be confirmed by capnography. * If the endotracheal tube hits the arytenoid cartilages and cannot be advanced further, the anaesthetist can retract it slightly (to release the tip from the cartilage), twisting it carefully counter clockwise and reducing the cricoid pressure (if applied). Stylets Lighted Stylet The lighted stylet is a useful device for managing difficult airways, especially when the difficulty is due to an anteriorly positioned glottis [13] (Fig. 2). However, it should not be used in patients with anatomical abnormalities of the upper airways, such as traumas, tumours, infections, or foreign bodies [14]. The lighted stylet has a bright light on its distal tip to locate the glottis by transillumination through the soft tissues of the neck, thus enabling indirect

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visualisation of tracheal tube placement. When intubating with a lighted stylet, the clinician cannot directly visualise the internal structures but must recognise when the stylet is in the midline (trachea), as opposed to in the oesophagus or displaced to the side (soft tissue).

Fig. (2). Aaron Surch-lite™ Orotracheal Stylet, Tiger Medical, Inc.

Aside from facilitating intubation in patients with an anterior glottis, the advantages of this technique include a lower risk of pharyngeal trauma compared to direct laryngoscopy [15] and reduced need for neck hyperextension [16, 17]. The haemodynamic changes are similar or even less significant than with direct laryngoscopy [13, 16 - 18]. The lighted stylet can also be used in nasotracheal intubation [18, 19]. Optical Stylets Optical stylets (OS) are metal stylets with a fibreoptic bundle or video camera on the distal tip. They can be rigid, semi-rigid, or flexible. They are used less frequently than videolaryngoscopes. Optical stylets require less mouth opening than videolaryngoscopes (in theory, only enough to insert the endotracheal tube) but they provide a smaller visual field. Although they are more expensive than lighted stylets, they are cheaper than videolaryngoscopes and fibreoptic bronchoscopes. Some optical stylets can be connected to an external monitor for better visualisation or as an application in teaching or supervision. Many of these devices also have a side port through which oxygen can be administered to prevent secretions covering the fibreoptic tip of the stylet, which would obstruct vision. The most commonly used optical stylets are the Bonfils (Fig. 3), the Fiberscope

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(Storz), the Levitan FPS (Clarus), and the Video System (Clarus). Models for adult patients have an exterior diameter of 5 mm, which means they can be used with endotracheal tubes with an internal diameter of 5.5 mm or more. All optical stylets must be treated with an anti-fog solution or kept warm until use. The tip of the stylet must remain inside the endotracheal tube to prevent injury.

Fig. (3). Intubation with Bonfils.

●

Technique: Firstly, the tip of the stylet is prepared by covering it with an antifog solution or keeping it warm until ready for use. The stylet is lightly lubricated before the endotracheal tube is placed over it, at which point the clinician must ensure that the tip of the stylet is near the distal end of the endotracheal tube. The patient is placed in the optimal position for ventilation with a face mask and a direct laryngoscope. If the stylet is flexible, it should be shaped accordingly at this point.

Optical stylets can be used alone or in combination with a laryngoscope, which is useful for identifying the epiglottis before inserting the stylet. When used alone, the stylet should be inserted as follows: The Bonfils stylet is traditionally designed for retromolar placement in the oral cavity, but it can also be inserted along the midline (no published studies have compared the two techniques). It is then advanced slowly, with reference structures such as the uvula and the epiglottis serving to prevent misplacement. Using these structures is very important as optical stylets provide a small visual field. After identifying the epiglottis, using our free hand, the patient's jaw will be lifted with the thumb (placing it on the patient’s tongue) and index finger, in order to see the vocal cords. This jaw lift manoeuvre can be performed by an assistant,

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especially if the patient has removable dental prostheses. The stylet and tube are advanced past the vocal cords, but only the tube is advanced into the trachea, to prevent airway injury. There are fewer published studies on the complications associated with these devices than on those associated with videolaryngoscopes. Most complications reported are related to technique failure resulting in intubation failure, while less common complications involve traumas [20] and technical difficulties due to secretions or device fogging. EXCHANGE CATHETERS AND STAGED EXTUBATION SETS IN AIRWAY MANAGEMENT Extubation has been considered as a sub-section within the guide of difficult airway management. This is despite the fact that a large number of patients may suffer morbidity or mortality directly associated with this part of the anaesthesia [21]. Tracheal extubation should be considered as important as the tracheal intubation for all patients [22]. Extubation failure is often defined as the need for re-intubation within 24-72 h of planned extubation [23]. Extubation is difficult because it is necessary to consider the airway conditions including: excess laryngeal reflex, reduced airway reflex, laryngeal reflex dysfunction, atelectasis, reduced functional residual capacity, and the influence of the surgical procedure, such as airway injury [24]. Intubation without complications does not necessary means extubation without complications. Therefore, an action plan for airway management should be taken [21]. The risk factors including in the Difficult Airway Society Guidelines for Management of Tracheal Extubation are the following [23]: 1. Pre-existing airway difficulties. 2. Perioperative airway deterioration (Surgical factors such as anatomical distortion, haemorrhage, hematoma and edema or Nonsurgical factors such as dependent edema due to positioning, airway trauma from prior airway management and aggressive fluid management). 3. Restricted airway access (Halo fixation, mandibulo-maxillary fixation, surgical implants, cervical collar or Large head/neck dressings). In 2012, The Difficult Airway Society recommended the use of an airway Exchange catheter (AEC)- assisted tracheal extubation to all risk patients (Fig. 4). The AEC maintains a conduit with the trachea after the extubation to allow airway rescue and may also be used for insufflation of oxygen and jet ventilation [25]. The anaesthetist should consider it for every difficult extubation.

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AECs are long hollow semirigid catheters that are designed to be used on the ETT Exchange. Its interior is hollow and has a removable adapter “Rapi-fit” that allows the use of ventilation devices during the exchange procedure if necessary (jet ventilation) and also has a conventional 15 mm connector for connection to the anaesthesia circuit or Ambu bag and one with a Luer-Lok connector for jet ventilation to deliver oxygen to the patient [24]. The tube exchange guide is based on the Seldinger technique [21]. This technique consists of introducing the exchange “guide” that previously was lubricated inside the endotracheal tube. It should be placed at a similar depth that of the tube in order not to reach the carina and avoid barotrauma, perforation of the bronchus or pulmonary parenchyma.

Fig. (4). Cook® Airway Exchange Catheter.

These catheters should be inserted to a depth of 20-22 cm (not more than 25 cm) when used for orotracheal intubation; when used for nasotracheal intubation, a depth of 27-30 cm is appropriate. Before removing the tube, the anaesthetist must verify with capnography that the guide is in the trachea. This system allows us to use a jet ventilation method and facilitate reintubation if necessary. Other purposes of the AEC are: Exchange from nasal to oral endotracheal tube and the cases of laryngeal tubes [26]. Two fiberoptic bronchoscope (FOB) facilitated techniques have been described to Exchange an LT for an ETT: an intraluminal technique using an Aintree intubating catheter and an extraluminal technique using a nasal route alongside LT. For the extraluminal technique, the

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FOB should be inserted orally, going around the deflated pharyngeal cuff, and then into the trachea. In the case of the intraluminal technique, the catheter must go into the trachea through the ventilation channel of the LT [27]. The recommended lengths for the exchange catheters are the following [21]: ●

●

●

Patients with a difficult airway but without respiratory problems or edema, 1 hour. Patients with difficult airway but without respiratory problems with possible edema > 2 hours. Patients with a difficult airway with associated respiratory problems or previous extubation failure > 4 hours and finally in patients with a difficult airway, respiratory or neurological disorder associated between 4 hours and 72 hours.

PATIENTS THAT NEED SPECIAL EXTUBATION CATEGORIZED IN ONE OF THESE THREE CASES [28]

MAY

BE

Case 1: Extubation in a standard airway with a need for suppression of hemodynamic responses: Tracheal extubation has been associated with an increase of 10% to 30% in blood pressure and heart rate. Patients are extubated when they are awake or under deep inhalational anaesthesia. When the patient is extubated in awake state, in order to avoid the hemodynamic response, the anaesthetist can use pharmacological agents such as topical lidocaine 10%, intravenous b-blocker, fentanyl 0.5-1 mcg/kg, dexmedetomidine 0.75 mcg/kg (15 min before extubation), or remifentanil infusion [23] (at the time of extubation). Another technique used is to replace the ETT with a supraglottic airway device (SAD) under deep anaesthesia. This procedure, demonstrated to reduce hemodynamic stress or coughing. Techniques of exchanging and ETT for a SAD at emergence include as follows. Blind removal of ETT and insertion of SAD. Insertion of SAD with ETT in situ. SAD is placed behind the ETT, and thereafter, ETT is removed (Bailey manoeuvre) [22]. Removal of ETT over an airway Exchange catheter (AEC) and railroading the LMA through its airway lumen into the pharynx for its placement. Nevertheless, there is a possibility of losing the airway during the exchange procedure [29]. Case 2: Extubation with a difficult airway that includes: difficult mask ventilation, difficult intubation/reintubation or airway difficulty due to preexisting disease. The anaesthetist must ensure a full recovery regarding the conscious level and neuromuscular recovery. All patients should receive 100%

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oxygen to improve oxygen reserve. If necessary, tracheal extubation could be done over an AEC/fibre-optic bronchoscope (FOB). Case 3: Extubation with a difficult airway due to a complication during the surgery such as airway oedema or airway collapse. In these cases, the anaesthetist suggests performing a cuff-leak test [30] before extubation to check if there is airway oedema or collapsibility of the airway. A cuff leak refers to normal airflow around the ETT after the cuff of the ETT is deflated. In case there is no normal airflow, it suggests a reduced space between the ETT and the larynx. This could be due to laryngeal edema, another laryngeal injury, secretions, or a large ETT within a relatively small larynx. The cuff leak can be detected qualitatively or quantitatively. Qualitative assessment is performed by deflating the cuff to listen for air movement around the ETT using a stethoscope placed over the upper trachea. Quantitative assessment is performed by deflating the ETT cuff and measuring the difference between the inspired and expired tidal volumes of ventilator-during volumecycled mechanical ventilation. The lowest three expired tidal volumes obtained over six breaths are average and then subtracted from the inspired tidal volume to give the cuff leak volume. Cuff leak volumes less than 110 ml or less than 12 to 24 percent of the delivered tidal volume have been suggested as thresholds for determining whether airway patency may be diminished. The algorithm for extubation is comprised of four procedures [24, 30]: ●

●

●

Step 1: Plan Extubation [22]: In the case of low risk, extubation is a routine one and without any complications. In the case of the high risk of extubation, there are risk factors in the airway that may be prior to the induction, due to perioperative deterioration or due to restricted access on the airway. Step 2: Prepare for Extubation: It is recommended to review the pharyngolaryngeal structures with a fiberscope or direct laryngoscopy [21]. Also, it is important to consider the risk factors such as airway trauma, edema, infections and secretions in the low airway that may be contraindicate extubation. If necessary, a rescue plan should include subglottic access, approachability to the neck should be confirmed. Step 3: Perform Extubation: There is a key question the anaesthetist must ask “is it safe to remove the tube? If the answer is “Yes”, the anaesthetist should proceed to an “Awake extubation” or “Advanced techniques” (laryngeal mask or extubation with AEC). If the answer is “No”, the anaesthetist must consider the “Postponement of extubation” and “Tracheotomy”.

The extubation will be performed when the patient is awake, that is with reflexes

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recovered so the patient can protect its airway, without paradoxical breathing, but with hemodynamic stability, it must present a complete recovery of the neuromuscular block. Oxygen reserves (preoxygenation) must be increased before extubation. This is vital as it is in the induction. It is convenient to increase the FiO2 above 0.9-1. Another option in performing extubation is when the patient is still asleep, without reflexes and without spontaneous ventilation: in this case, the anaesthetist can use a facial mask or laryngeal mask. This is considered as an alternative by some authors as an intermediate step but it has been criticized by others as it is considered a particularly risky practice when it comes to situations with a known difficult airway. There are some criteria for extubation [23, 26]: ● ● ● ● ● ●

Breathing frequency < 30 breaths /min. Maximum inspiratory pressure < 20 cmH20. Vital capacity > 15 ml/kg, tidal volume > 6 ml/kg. Hemodynamically stable with no significant inotropic support. Adequate gas exchange. Adequate neuromuscular block reversal.

-Step 4: Post-Extubation Cares: Recovery and follow-up After extubation, the patient must be managed in the ICU o reanimation. All patients should be closely monitored following extubation [30, 31]. COMPLICATIONS ASSOCIATED WITH EXTUBATION [21, 26, 32] Hemodynamic Alterations: Extubation with an awake or semi-awake patient produces a significant increase in heart rate and blood pressure. It is reasonable to try to attenuate the hemodynamic response to extubation in patients with cardiovascular pathology, intracranial hypertension or with limited myocardial reserve. The administration of β-blockers and lidocaine 1 to 2 mg/kg intravenously, 2 to 3 minutes before extubation may attenuate this response. Hypoventilation: It is essential to notice the ventilatory pattern adopted by the patient, pharmacological reversal, adequate analgesia and the administration of supplemental oxygen and maintaining a positive pressure in the airway after extubation can avoid reintubation in these cases. Residual neuromuscular blockade [23], known as a train-of-four ratio of < 0.9, can manifest as weaning or extubation failure. Studies in postsurgical patients have proven a high incidence of postoperative residual curarization after extubation whether or not reversal with neostigmine was administered.

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Accidental Extubation: This may occur by insufficient fixation of the tube, by movements of the patient and when the surgeon works on the airway. Laryngospasm: Laryngospasm is a normal cause of upper airway obstruction right after extubation that can lead to extubation failure. Its global incidence is 8/1000 patients. Laryngospasm is an excessive glottal closure reflex [22] caused by the stimulation of the superior laryngeal nerve. When the glottic closure is complete and does not give away after ventilation with positive pressure to the airway, the administration of a neuromuscular relaxant may be needed to allow the opening of the vocal cords and help the patient's ventilation. If laryngospasm persists and oxygenation by facemask is not satisfactory, reintubation will be necessary to control the airway. In any case, the best treatment of glottis spasm is based on its prevention. Intravenous anaesthesia using propofol is related to a lower incidence of complications related to exaggerated reflexes. Pulmonary Edema by Negative Pressure (NPPE): This may result in spontaneously breathing patients when laryngospasm or other reasons for airway obstruction occur following extubation. This condition is seen within minutes after extubation. NPPE is a potentially life-threatening complication with a multifactorial pathogenesis. Frequently, the principal mechanism involved is the generation of high negative intrathoracic pressure (NIP) needed to overcome upper airway obstruction (UAO) [33]. This negative pressure finally causes a form of noncardiogenic pulmonary edema (PE) secondary to an increase in pulmonary vascular volume and pulmonary capillary transmural pressure, which can cause the rupture of the alveolar–capillary membrane [34]. Bronchospasm: Bronchospasm may present as an expiratory wheeze, prolonged expiration and/or increased inflation pressure during intermittent positive-pressure ventilation (IPPV). Range of auscultation can go from complete silence on auscultation or a few quiet musical notes at the end of exhalation to loud discordant expiratory noise. It can be secondary to laryngotracheal stimulation or histamine release, among other causes. Periglottic or Laryngotracheal Damage: Subglottic edema is often seen in children, particularly infants and neonates. Post-extubation subglottic edema is characterized by the presence of stridor, thoracic retraction, croup, and varying degrees of ventilatory obstruction. The treatment of subglottic edema consists of adapting the position of the airway, administering non-humidified and heated oxygen, and nebulization with adrenaline 0.5-5 micrograms/kilogram. If the symptoms are not fixed with nebulization’s every half an hour or signs of hypoventilation and -/- or hypercapnia appear, the patient should be re-intubated.

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Risk factors for postextubation laryngeal edema include [35]: ● ● ●

● ● ● ● ● ● ● ●

Prolonged intubation (variably defined as 36 hours to 6 days). People older than 80 years. A large endotracheal tube (> 8 mm in men, > 7 mm in women), a ratio of ETT to a laryngeal diameter greater than 45 percent, or a small ratio of patient height to ETT diameter. Elevated Acute Physiology and Chronic Health Evaluation (APACHE) II score. A Glasgow Coma Scale/Score (GCS) < 8. Traumatic intubation. Female gender. History of asthma. Excessive tube mobility due to insufficient fixation. Insufficient or lack of sedation Aspiration.

Paralysis of Vocal Cords: It is frequently secondary damage to post-surgical nerve injury of the inferior or laryngeal nerve, and -/- or of the superior laryngeal nerve, especially in head and neck surgeries, thyroid, carotid endarterectomy, thoracic, and maxillofacial surgery. Hoarseness and aspiration occur in unilateral paralysis, and dyspnea occurs in bilateral paralysis, for which tracheotomy is the most [26]. Tube Trapping: Related to malfunction of the pilot valve of the pneumo-balloon tube or to the dire situation of the fixation of the tube to the trachea or the bronchus in the situation of a double-lumen tube through sutures or staples during the surgical procedure. The anaesthetist should never force the withdrawal of the tube if suspect some identified difficulty since its complications can be mortal. Finally, it is important to recall that the doctor should have a preformulated strategy for extubation of the difficult airway. This strategy will depend on the surgery, the condition of the patient, and the skills and preferences of the anaesthesiologist. CONCLUSION ●

●

●

When direct laryngoscopic visualization of the glottis may not be possible intubating guides, stylets and introducers have been developed and have proved to be effective, safe and simple approaches. Besides, first-attempt intubation success among patients undergoing emergency endotracheal intubation used to be higher. Although stylets are malleable, they should be considered rigid intubating aids

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and therefore never be advanced into the patient's larynx or trachea due to the risk of causing significant trauma. CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that the contents of this chapter have no conflict of interest. ACKNOWLEDGEMENT Declare none. REFERENCES [1]

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Cook TM, Woodall N, Frerk C. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 1: anaesthesia. Br J Anaesth 2011; 106(5): 617-31. [http://dx.doi.org/10.1093/bja/aer058] [PMID: 21447488]

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Apfelbaum JL, Hagberg CA, Caplan RA, et al. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anaesthesiologists Task Force on Management of the Difficult Airway. Anaesthesiology 2013; 118(2): 251-70. [http://dx.doi.org/10.1097/ALN.0b013e31827773b2]

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Kidd JF, Dyson A, Latto IP. Successful difficult intubation. Use of the gum elastic bougie. Anaesthesia 1988; 43(6): 437-8. [http://dx.doi.org/10.1111/j.1365-2044.1988.tb06625.x] [PMID: 3407866]

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Marson BA, Anderson E, Wilkes AR, Hodzovic I. Bougie-related airway trauma: dangers of the holdup sign. Anaesthesia 2014; 69(3): 219-23. [http://dx.doi.org/10.1111/anae.12534] [PMID: 24548354]

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Agrò F, Hung OR, Cataldo R, Carassiti M, Gherardi S. Lightwand intubation using the Trachlight: a brief review of current knowledge. Can J Anaesth 2001; 48(6): 592-9. [http://dx.doi.org/10.1007/BF03016838] [PMID: 11444456]

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Amornyotin S, Sanansilp V, Amorntien V, Tirawat P. Effectiveness of lightwand (Trachlight) intubation by 1st year anesthesia residents. J Med Assoc Thai 2002; 85 (Suppl. 3): S963-8. [PMID: 12452236]

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Turkstra TP, Pelz DM, Shaikh AA, Craen RA. Cervical spine motion: a fluoroscopic comparison of Shikani Optical Stylet vs Macintosh laryngoscope. Can J Anaesth 2007; 54(6): 441-7. [http://dx.doi.org/10.1007/BF03022029] [PMID: 17541072]

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Turkstra TP, Craen RA, Pelz DM, Gelb AW. Cervical spine motion: a fluoroscopic comparison during intubation with lighted stylet, GlideScope, and Macintosh laryngoscope. Anesth Analg 2005; 101(3): 910-5. [http://dx.doi.org/10.1213/01.ane.0000166975.38649.27] [PMID: 16116013]

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Hirabayashi Y, Hiruta M, Kawakami T, et al. Effects of lightwand (trachlight) compared with direct laryngoscopy on circulatory responses to tracheal intubation. Br J Anaesth 1998; 81(2): 253-5. [http://dx.doi.org/10.1093/bja/81.2.253] [PMID: 9813535]

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Kihara S, Brimacombe J, Yaguchi Y, Watanabe S, Taguchi N, Komatsuzaki T. Hemodynamic responses among three tracheal intubation devices in normotensive and hypertensive patients. Anesth Analg 2003; 96(3): 890-5. [http://dx.doi.org/10.1213/01.ANE.0000048706.15720.C9] [PMID: 12598280]

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Murphy M, Walls RM. Identification of the Difficult and Failed Airway. Manual of Emergency Airway Management, 3rd. Philadelphia: Lippincott 2008; p. 81.

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Favaro R, Tordiglione P, Di Lascio F, et al. Effective nasotracheal intubation using a modified transillumination technique. Can J Anaesth 2002; 49(1): 91-5. [http://dx.doi.org/10.1007/BF03020426] [PMID: 11782336]

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Halligan M, Charters P. A clinical evaluation of the Bonfils Intubation Fibrescope. Anaesthesia 2003; 58(11): 1087-91. [http://dx.doi.org/10.1046/j.1365-2044.2003.03407.x] [PMID: 14616594]

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De la Linde Valverde CM. La extubación de la vía aérea difícil. REDAR 2005; 52: 557-70.

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extubation from United Kingdom. Manual de manejo de la vía aérea difícil. 3rd ed. AnestesiaR.org 2017; pp. 232-45. [26]

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Nagata M, Shimomura Y, Hara Y, et al. A devised strategy for tracheal extubation for predicted difficult airway in a child with unilateral vocal cord paralysis: a case report. JA Clin Rep 2017; 3(1): 21. [http://dx.doi.org/10.1186/s40981-017-0091-8] [PMID: 29457065]

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Lee SH, Kim JE, Kang JM. Alternative technique for changing from nasal to oral endotracheal tube for orthognathic and nasal surgery by using an airway exchange catheter: a case report. Korean J Anesthesiol 2014; 67(1): 48-51. [http://dx.doi.org/10.4097/kjae.2014.67.1.48] [PMID: 25097739]

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Kundra P, Garg R, Patwa A, et al. All India Difficul Airway Association 2016 guidelines for the management of anticipated difficult extubation. Indian Journal of Anaesthesia 2016; 60: 915-21.

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Raveendran R, Sastry SG, Wong DT. Tracheal extubation with a laryngeal mask airway and exchange catheter in a patient with a difficult airway. Can J Anaesth 2013; 60(12): 1278-9. [http://dx.doi.org/10.1007/s12630-013-0041-5] [PMID: 24097300]

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CHAPTER 7

An Update on Can't Intubate, Can't Oxygenate Situation (CICO) Scenarios María Eugenia Centeno Robles1,*, Emilio Herrero Gento1, María Paez Hospital1 and María Elena Pinilla Carbajo1 Departamento de Anestesiología y Reanimación, Complejo Asistencial, Universitario de Palencia, Spain 1

Abstract: A difficult airway is defined as the clinical situation in which a conventionally trained anaesthesiologist experiences difficulty with facemask ventilation of the upper airway, difficulty with tracheal intubation, or both. The greatest challenge is “cannot intubate and cannot oxygenate (CICO)” scenarios. This is a true emergency situation because if spontaneous effective breathing does not recover and the surgical airway cannot be established, CICO often ends in a catastrophe.

Keywords: Bougie, Brain damage, Cricothyroidotomy, Death, Emergency, Hypoxia, Intubation, Oxygenation, Scalpel, Supraglottic, Ventilation, Videolaryngoscope. INTRODUCTION A difficult airway is defined as the clinical situation in which a conventionally trained anaesthesiologist experiences difficulty with facemask ventilation of the upper airway, difficulty with tracheal intubation, or both [1]. The difficult airway represents an interaction between patient factors, the clinical setting, and the skills of the anaesthesiologist. The induction of general anaesthesia impairs control of the upper airway maintenance mechanisms. Failure of airway control is a cause of cardiorespiratory arrest and death associated with general anaesthesia [2]. Corresponding author María Eugenia Centeno Robles: Complejo Asistencial, Universitario de Palencia, Spain; Tel: 0034 979 16 70 00; E-mail: [email protected]

*

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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The greatest challenge is “cannot intubate and cannot oxygenate (CICO)” scenarios. This is a true emergency situation because if spontaneous effective breathing does not recover and the surgical airway cannot be established, CICO often ends in catastrophe [3].Preparation for the management of a difficult airway should include: appropriateinformation to patients with a difficult airway known or suspected, appropriate material for handling an unexpected difficult airway situation, denitrogenation prior to induction of general anaesthesia with a face mask and supplemental oxygen throughout the process of managing the difficult airway [1]. Good communication between anaesthetists and anaesthetic assistants is very important. Talking before every patient about the plan to manage difficulties is essential for good practice. Sometimes facial mask ventilation is possible at first and failed attempts of tracheal intubation lead to a “non-intubatable, non-ventilate” situation. For this reason, we should focus on maintaining oxygenation and not continue to try to intubate the trachea [4]. MANAGEMENT OF UNANTICIPATED INTUBATION IN ADULTS

DIFFICULT

TRACHEAL

In 2015, Difficult Airway Society published updated guidelines for the management of unanticipated difficult intubation in adults [5]. These guidelines propose consecutive plans to follow if tracheal intubation is not possible (Fig. 1).

Fig. (1). Difficult Airway Society difficult intubation guidelines: an overview. Difficult Airway Society, 2015, by permission of the Difficult Airway Society. (www.das.uk.com/files/das2015intubation_ guidelines.pdf).

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Plan A: Mask Ventilation and Tracheal Intubation The guidelines recommend a maximum of three attempts at intubation (a fourth attempt by a more experienced colleague is permissible). Maintenance of oxygenation is the priority. All anaesthetists should be trained and familiar with the use of the videolaryngoscope. If intubation fails, move to the next step. Plan B: Maintaining Oxygenation: Supraglottic Airway Device Insertion Second-generation laryngeal masks (SADs) are recommended and a maximum of three attempts are recommended for insertion. Intubation through the laryngeal mask is only suitable if the oxygenation is correct and the anaesthesiologist is accustomed to the technique. In case of intubation through the laryngeal mask it would be preferable to use a fiberscope [6]. If after three attempts the oxygenation is not effective, move to the third step. Plan C: Final Attempt at Face-Mask Ventilation If the ventilation through the face mask is possible, we will have to wake up the patient (except in exceptional circumstances). If face mask ventilation is not possible, ensuring full paralysis offers the final chance to oxygenate the patient. If unsuccessful, CICO situation must be declared. Plan D: CICO Situation. Emergency Front of Neck Access When CICO situation is declared, brain injury and/or death will inevitably happen if the situation is not resolved quickly. Cricothyroidotomy will be done, either with a scalpel or with a cannula. The training of all anaesthesiologists in carrying out cricothyroidotomy with a scalpel is recommended [2] (Fig. 2). There is evidence that surgical cricothyroidotomy is faster and therefore more interesting in CICO situations [7]. In terms of the patient’s position, a neck extension is required, even putting a pillow under the shoulders. When the cricothyroid membrane is palpable, the anaesthetist must [5]:

● ●

●

●

Continue attempts at rescue oxygenation via the upper airway (assistant). Stand on the patient’s left-hand side if you are right-handed (reverse if lefthanded). Perform a laryngeal handshake to identify the laryngeal anatomy. Stabilize the larynx using the left hand. Use the left index finger to identify the cricothyroid membrane. Hold the scalpel in your right hand, make a transverse stab incision through the

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skin and cricothyroid membrane with the cutting edge of the blade facing towards you. Keep the scalpel perpendicular to the skin and turn it through 90° so that the sharp edge points caudally (towards the feet). Swap hands; hold the scalpel with your left hand. Maintain gentle traction, pulling the scalpel towards you (laterally) with the left hand, keeping the scalpel handle vertical to the skin (not slanted). Pick the bougie up with your right hand. Holding the bougie parallel to the floor, at a right angle to the trachea, slide the coude tip of the bougie down the side of the scalpel blade furthest from you into the trachea. Rotate and align the bougie with the patient’s trachea and advance gently up to 10–15 cm. Remove the scalpel. Stabilize trachea and tension skin with the left hand. Railroad a lubricated size 6.0 mm cuffed tracheal tube over the bougie. Rotate the tube over the bougie as it is advanced. Avoid excessive advancement and endobronchial intubation. Remove the bougie. Inflate the cuff and confirm ventilation with capnography. Secure the tube.

If we are unable to palpate the cricothyroid membrane or if the previous technique fails, we will continue the oxygenation attempts and make a vertical incision in the midline to try to identify the cricothyroid membrane. Cricothyrotomy is considered a temporary airway [8]. Studies suggest that although cricothyrotomy is the emergent airway of choice, emergent tracheostomies are also safe and may be performed more often [9, 10]. It is estimated that the percentage of acute complications of emergent cricothyrotomy is 15% and these include haemorrhage, poor positioning of the endotracheal tube, damage to adjacent neck structures, and pneumothorax. The Difficult Airway Algorithm of the American Society of Anaesthesiologists (ASA) advises when ventilation is not adequate and intubation is unsuccessful, call for help and try emergency non-invasive airway ventilation with supraglottic airway devices (SAD). If SAD placement fails, an emergency invasive airway access will be necessary. Invasive airway access includes retrograde intubation, jet ventilation, and surgical or percutaneous airway [1]. Japanese Society of Anaesthesiologists (JSA) airway management algorithm during induction of anaesthesia recommends in CICO scenarios the establishment

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of a surgical airway. They emphasize the correct identification of the cricothyroid membrane.

Fig. (2). Failed intubation, failed oxygenation in the paralysed, anaesthetized patient. Technique for scalpel cricothyroidotomy. Difficult Airway Society, 2015, by permission of the Difficult Airway Society. (das.uk.com/files/das2015intubation_guidelines.pdf).

If the membrane is palpable, they recommend the use of commercial cricothyrotomy kits. If the cricothyroid membrane is not identified or there are no available kits, they

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recommend performing a surgical cricothyrotomy. If the cricothyroid membrane cannot be identified after the surgical incision, a surgical tracheostomy is indicated [11]. In the case of a CICO situation, it is necessary to proceed without delay to the establishment of a surgical airway as it will be the only way to save the patient's life. Maintenance of the technical as well as psychological skills to handle difficult airway is critically important for all anaesthesiologists. Knowing the physiology of the airway, updated techniques and using easy algorithms are key elements of our daily good practice [12]. CONCLUSION ●

●

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●

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There is no method of intubation with 100% success. “Cannot intubate, cannot oxygenate” (CICO) scenario exists, and we must be prepared to face it. Transcutaneous techniques are not easy handling, and their training is scarce during the training period and later. Theoretical-practical courses must be carried out, with mannequins and simulation techniques that allow to knowing in depth these techniques and gain skills in its management. It is essential that each specialist knows the means available to manage a CICO situation. This includes cricothyrotomy, tracheotomy and retrograde intubation set. Not only medical doctors must be trained, but all the health personnel that can be involved in these types of scenarios.

CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that the contents of this chapter have no conflict of interest. ACKNOWLEDGEMENTS Declared none. REFERENCES [1]

Apfelbaum JL, Hagberg CA, Caplan RA, et al. ASA Practice guidelines for management of the difficult airway: an updated report by the American Society of Anaesthesiologists Task Force on Management of the Difficult Airway. Anaesthesiology 2013; 118: 251-70.

[2]

Cook TM, Woodall N, Frerk C. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 1: anaesthesia. Br J Anaesth 2011; 106(5): 617-31.

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[http://dx.doi.org/10.1093/bja/aer058] [PMID: 21447488] [3]

Cheney FW, Posner KL, Lee LA, Caplan RA, Domino KB. Trends in anesthesia-related death and brain damage: A closed claims analysis. Anesthesiology 2006; 105(6): 1081-6. [http://dx.doi.org/10.1097/00000542-200612000-00007] [PMID: 17122570]

[4]

Liu EH, Asai T. Cannot intubate cannot ventilate-focus on the ‘ventilate’. J Anesth 2015; 29(3): 323-5. [http://dx.doi.org/10.1007/s00540-014-1858-y] [PMID: 24943454]

[5]

Frerk C, Mitchell VS, McNarry AF, et al. Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults. Br J Anaesth 2015; 115(6): 827-48. [http://dx.doi.org/10.1093/bja/aev371] [PMID: 26556848]

[6]

Joo HS, Kapoor S, Rose DK, Naik VN. The intubating laryngeal mask airway after induction of general anesthesia versus awake fiberoptic intubation in patients with difficult airways. Anesth Analg 2001; 92(5): 1342-6. [http://dx.doi.org/10.1097/00000539-200105000-00050] [PMID: 11323374]

[7]

Heard AMB, Green RJ, Eakins P. The formulation and introduction of a ‘can’t intubate, can’t ventilate’ algorithm into clinical practice. Anaesthesia 2009; 64(6): 601-8. [http://dx.doi.org/10.1111/j.1365-2044.2009.05888.x] [PMID: 19453312]

[8]

Patel SA, Meyer TK. Surgical airway. Int J Crit Illn Inj Sci 2014; 4(1): 71-6. [http://dx.doi.org/10.4103/2229-5151.128016] [PMID: 24741501]

[9]

Brennan J, Gibbons MD, Lopez M, et al. Traumatic airway management in Operation Iraqi Freedom. Otolaryngol Head Neck Surg 2011; 144(3): 376-80. [http://dx.doi.org/10.1177/0194599810392666] [PMID: 21493199]

[10]

Bobek S, Bell RB, Dierks E, Potter B. Tracheotomy in the unprotected airway. J Oral Maxillofac Surg 2011; 69(8): 2198-203. [http://dx.doi.org/10.1016/j.joms.2011.01.041] [PMID: 21601339]

[11]

JSA airway management guideline 2014. For improving safety of anaesthesia induction. J Anesth in press.

[12]

Grande B, Kolbe M, Biro P. Difficult airway management and training: simulation, communication, and feedback. Curr Opin Anaesthesiol 2017; 30(6): 743-7. [http://dx.doi.org/10.1097/ACO.0000000000000523] [PMID: 28957878]

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CHAPTER 8

An Update on Bronchoscopy and Other Airway Device Updates Norma Aracil Escoda1,*, Ana Tirado Errazquin1, Elena Sáez Ruiz1, Paloma Muñoz Saldaña1 and Olivia Espinosa de los Monteros2 Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Infanta Leonor, Madrid, Spain 2 Department of Cellular Pathology, John Radcliffe Hospital Oxford, UK 1

Abstract: In 1954, the first coherent fiberoptic bundle capable of transmitting an image was built, and in 1958, the first flexible fibergastroscope prototype. In 1967, Murphy introduced the technique of tracheal intubation by a coledoscope, through which he slid a 7.5 mm endotracheal tube (ETT) into the nasopharynx, visualizing only the entrance to the larynx because it was too short to guide the ETT. In 1968, the first fiberoptic bronchoscope (FBO) was constructed and, later, 60 cm. insertion cords appeared. In 1972, a series of 100 intubations with FBO was published with 96% success. Following the publication of the ASA airway management guidelines of 1993, the use of FBO increased considerably, becoming the gold standard for Difficult Airway (DA).

Keywords: Airway management, aScope, Bronchoscopes, Cricothyroid Membrane, Difficult airway, Fibro-bronchoscopes, Intubation, Intratracheal, Laryngoscopy, Predictors, Tracheostomy, Videolaryngoscope. INTRODUCTION Bronchoscopy is an endoscopic technique that, by placing an optical instrument into the airways, enables us to view the tracheobronchial tree and allows the operator to assess the appropriate access technique for intubation. Fibro-bronchoscopes (flexible bronchoscopes using fiberoptic transmission) are widely used and used to be the gold standard in difficult airway management, but this concept is changing. Initially, the introduction of the rigid videolaryngoscopes and, later, flexible devices, has been useful in situations of difficult airway management in both awake and asleep patients. Corresponding author Norma Aracil Escoda: Department of Anesthesiology and Intensive Care. Hospital Universitario Infanta Leonor, Madrid, Spain; Tel: 0034 911 91 80 00; E-mail: [email protected]

*

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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Its combination is opening new horizons in airway management. HISTORY An endoscopic procedure is defined as a technique that uses an endoscope to examine the interior of a hollow organ or cavity of the body. The self-illuminated endoscope was developed at Glasgow Royal Infirmary in Scotland in 1894/5 by Dr. John Macintyre as part of his specialization in the investigation of the larynx [1]. Basil Hirschowitz and Larry Curtiss developed the first fibre optic endoscope in 1957 [2]. This was based on the earlier 1950s Harold Hopkins´s “fiberscope” which consisted of a bundle of flexible glass fibres able to coherently transmit an image [3]. Hirschowitz and Curtiss’s device was improved by the development of the flexible fiberoptic bronchoscope, which features a sterile single-use disposablesheath endoscope system. The latter was developed with the aim to reduce scope downtime by eliminating the need for high-level disinfection between procedures. It was the beginning of the age of reusable devices [4]. While flexible fiberoptic bronchoscopy has been widely used in difficult airway management, newer bronchoscopes no longer use fiberoptic technology due to its expensive and fragile nature and issues with strict maintenance and disinfection needs. The terms “flexible scope intubation” (FSI) and “flexible intubating scope” (FIS) will be used in this text to designate the indirect technique of endotracheal intubation using a flexible bronchoscope (FSI) and for the device (FIS), respectively. An important milestone was reached in 2010, with the emergence of the first single-use flexible video laryngoscope incorporating a miniaturised digital camera with a light-emitting diode (LED). In this device, the image is transmitted via an electric cable to a colour liquid crystal display (LCD) monitor. It operates without fibre optic bundles and it does not feature an integrated viewer. However, it has a small working channel [5]. In the last few years, new bronchoscopes have appeared, including some with reusable miniaturized digital cameras. The trend in recent years includes small monitors at the proximal end of the scope, located on the control handle, and therefore featuring a completely portable device. An example of this is the video flexible intubation scope: ENT

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flexiblescope model MCE-A30 or Electronic Endoscope Video laryngoscope UNICARE among others. DESCRIPTION The flexible bronchoscope is a device that can be used for indirect laryngoscopy and endotracheal intubation [6, 7]. It is particularly valuable when direct laryngoscopy is difficult or impossible, or in high-risk situations for the patient. It is also widely used to locate the vocal cords and acts as a stylet for the endotracheal tube (ETT) once the FIS is placed into the trachea [8]. TYPES OF BRONCHOSCOPY The main types of bronchoscopy [9] are: ●

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Flexible Bronchoscopy: Also known as standard white light bronchoscopy or in our case, with newer devices, “flexible intubating scope” (FIS) (Fig. 1). Rigid Bronchoscopy: This is based on a white light source too. However, compared to flexible bronchoscopy, it is a more rigid piece of equipment that can only access proximal airways. Virtual Bronchoscopy: This is a non-invasive form of bronchoscopy. It is an imaging modality that reconstructs the airways in a three-dimensional manner, with data derived from multirow detector X-ray CT scans. Unlike flexible and rigid bronchoscopy, it cannot be used to acquire samples. This technique may have a role in pre-bronchoscopy planning, endoscopy training, and endobronchial therapy. Its availability is limited to centres with expertise [10].

The Flexible intubating scope (FIS) consists of a flexible insertion cord that contains either optical fibres or a small camera at the tip, used to transmit images to an eyepiece or camera head. It has three parts: ●

●

The control handle: This is held by the operator and contains a lever to flex or extend the distal tip of the bronchoscope. It also has a suction port and an opening through which instruments (forceps, brushes, etc) are inserted into the working channel. The flexible shaft: This contains cables enclosed within a sheath that allows flexion and extension of the distal tip of the bronchoscope by moving the lever on the handle. It also contains lighting cables and imaging cables or, in the case of a “fiberscope”, a bundle of fiberoptics transmitting the image from the distal tip to the viewer (Eyepiece or a monitor). Modern instruments may be videoscopes; where a distal camera transmits an image to a screen for image capture. It has a working channel through which

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airway contents are aspirated and catheters or other instruments are directed through. The Distal Tip: This is the part of the bronchoscope that guides the operator through the patient's airway. It contains an image retrieval element (camera), an illumination component (light), and the opening of the working channel.

A newer single unit portable system is available that features a built-in small display monitor at the proximal end of the bronchoscope eliminating the need for any cables or attachment to an image processor.

Fig. (1). Flexible bronchoscopy, Olympus.

DIFFERENT TYPES OF FLEXIBLE INTUBATING SCOPE The Classic Fiberscope ● ●

This uses fiberoptic technology. It is expensive, fragile, and needs great care when handling. Bending or twisting any part of the insertion cord should be avoided to prevent the breakage of fiberoptic fibres.

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It is reusable, albeit subject to mandatory cleaning, disinfection, and sterilisation routines. It needs a light source. It can be either a portable battery-powered source or a hard-wired. The light source may be halogen, incandescent, or LED.

Flexible Video Bronchoscopes A camera transmits an image to a screen for image capture. ●

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Reusable: Such as C-MAC FIVE Flexible Intubation Video Endoscope (FIVE) (Fig. 2). Single-Use: It is always accessible, cost-efficient, and sterile straight from the pack. There are no repair costs and no complex post-use handling procedures. It is available in different sizes (Fig. 3).

Fig. (2). FIVE 3.0, Flexible Intubation Video Endoscopes (FIVE), KARL STORZ.

Fig. (3). aScope, AMBU.

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Nowadays, there are two generations on the market for aScope device: 3 or 4 Broncho. They differ in the quality of image, field depth, and in manoeuvrability. The same monitor is in use, but with updated software. ●

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aScope (4 Broncho or 3) Slim. It has a small outer diameter of 3.8mm. It is the ideal solution for a wide range of bronchoscopy procedures including difficult intubation and placement and control of double lumen tubes. aScope (4 Broncho or 3) Regular. It has a working channel width of up to 2.2 mm. It is a solution for a wide range of bronchoscopy procedures. aScope (4 Broncho or 3) Large. It has a working channel of 2.8mm which makes it highly suitable for the management of: Difficult intubation (orally). Bedside bronchoscopy procedures: ♦ Management of tough retained secretions. ♦ Broncho Alveolar Lavage (BAL). ♦ Percutaneous Dilatational Tracheostomy (PDT) (Fig. 4). ❍ ❍

Fig. (4). Percutaneous Dilatational Tracheostomy procedure with aScope, AMBU.

INDICATIONS OF FLEXIBLE INTUBATING SCOPE The use of Flexible scope intubation (FIS) to guide tracheal intubation has found its way into several airway management algorithms. FSI is a standard technique for every anaesthetist.

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FSI can be used in clinical settings where direct laryngoscopy is contraindicated, or in those situations in which direct laryngoscopy is not the safest option including the following [11]: ●

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Limited mouth opening, as the FIS will pass through a narrow oral opening or through the nose. Abnormal airway anatomy or a mass obstructing direct visualization of the vocal cords. Unstable cervical spine, when the movement of the spine should be minimized or avoided. Airway trauma airway requiring visualization of the larynx and trachea before intubation. Prone or lateral position requiring rescue intubation.

Both oral and nasal access are possible and appropriate for both anesthetized or awaked patients. For awake intubation, FIS is better tolerated than laryngoscopy with a standard laryngoscope. The oral route is more used, although the nasal route is preferred for patients with a severely limited mouth opening or a strong gag reflex, and when nasotracheal intubation is necessary for the surgical procedure. Other advantages of the nasal access are better tolerance than oral intubation by the awake patient and improved laryngeal view. The risks of nasal intubation, however, include local trauma and epistaxis and submucosal tunneling of the nasopharynx. For asleep intubation, anaesthetised patients often feature oropharyngeal obstruction as a result of reduced muscle tone, with subsequent contact of the soft palate, base of the tongue, and epiglottis with the posterior pharyngeal wall. This leads to other specialist equipment tools being needed in these situations. EQUIPMENT Accessories required to facilitate the insertion of the FSI, and provide ventilation are: Endoscopy facemasks, Bite blocks or specialised oral airways, adaptors for ventilation, anti-fogging and lubricating agents, equipment for topicalization, and a video monitor if our FSI needs it.

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Supraglottic devices designed to facilitate endotracheal intubation can be used along with flexible scopes and may be included with routinely stocked equipment. Oral Airway These are designed to keep the scope in the midline, to prevent a patient’s breathing from becoming obstructed and to act as a bite block for awake oral FSI. It is inserted into the mouth and upper throat. It is used only in patients under general anaesthesia, heavy sedation, or with excellent local anaesthetic topicalization of the tongue and pharynx to avoid eliciting a gag reflex in conscious patients. There are several types of oral airways [12, 13]: Ovassapian Intubating Airway This device is open on its back. It has a posterior channel location, which may limit access to “anterior” airways. This channel is absent near the tip. Incomplete rings along the posterior aspect allow for easy removal once the patient is intubated. Its disadvantage is that it is available in a single size that allows the introduction to up to a maximum TET of 8 mm. Berman II Intubation Airway It is more circular, and available in four sizes. It has a posterior channel and a lateral slit for removal. Williams Intubation Airway It is available in two sizes, and the distal half is cut. It has an anterior channel location. It has no lateral cleft, so the endotracheal tube must be removed by slipping it over the tracheal tube (Fig. 5). VAMA Intubation Airway This device is only available in Spain (Fig. 6). It presents an anterior piece that is removed when the endotracheal tube is inserted. The rest of the cannula is easily removed at a later stage. A line in the internal/posterior zone identifies the way for the FIS.

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Fig. (5). Williams intubation airway.

Fig. (6). VAMA intubation airway.

Facemask In healthy patients’ ventilation, it may not be necessary during the brief period required for flexible scope intubation. However, supplemental oxygen is useful in patients with decreased physiologic reserve or functional residual capacity, and especially with an anesthetized patient during the procedure. There are standard facemasks with a bronchoscopic adapter attached, or specialized endoscopy masks with an in-built port for the bronchoscope. Patil-Syracuse Mask It has an additional port with a soft silicone membrane to accommodate endotracheal tubes or different endoscopic devices.

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The port can be closed off with a plastic cap obtaining a seal around an endotracheal tube or bronchoscope. It is re-usable and can be autoclaved (Fig. 7).

Fig. (7). Patil-Syracuse mask.

Endoscopy Mask VBM Medizintechnik It has a flexible membrane like the other mask. After intubation, the membrane is pushed inside which allows easy removal of the mask (Fig. 8).

Fig. (8). Intubation with Endoscopy Mask VBM Medizintechnik and Williams intubation airway.

Endotracheal Tube (ETT) Advancing the ETT through the vocal cords over the FIS is a difficult moment

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during FSI, and it is a blind point during the procedure. It is easier to work with a warmed and softened ETT and placing it in warm saline prior to the procedure is an interesting alternative. It is interesting to place it in warm saline prior to the procedure. The best options are flexible ETT, tapered-tip ETT for use with intubating laryngeal mask airway (LMA), and a specialized ETT with a bull-nose tip (Parker Flex-Tip). USES OF FLEXIBLE INTUBATING SCOPE ● ●

● ● ● ●

Airway inspection, placing and checking endotracheal tube. Placement of Double Lumen Tube (DLT) and checking its placement after blind attempt [14]. Placing of Bronchial Blockers [15]. Bronchoscope-assisted bedside percutaneous tracheostomy [16, 17]. Diagnostic and therapeutic endoscopic procedures such a BAL procedure [18]. Combined Use: Supraglottic Airway Devices (SAD): They can be used as a conduit for endotracheal intubation supported by a FIS, enabling patient ventilation. Fiberoptic laryngoscopy through the LMA was reported first by Payne [19]. Some SGAs (i-gel, LMA Fastrach, air-Q) allow direct insertion of an endotracheal tube (ETT). Nevertheless, standard laryngeal mask airways (LMAs) are too narrow to allow it with a standard TET size [20, 21]. This situation can be solved by using an Aintree intubation catheter [22, 23] (Figs. 9 and 10). ❍

Aintree intubation catheter is a blunt-tipped, 19 Fr, radio-opaque catheter with an internal diameter of 4.7 mm that allows introducing a FIS through it. The kit includes two connectors (one with a standard 15 mm tube connector and another with a Luer-lock connector) and a soft-seal swivel adaptor to enable ongoing ventilation whilst placing the catheter. The smallest suitable ETT which accommodates the device is a 6.5 ETT [24]. Videolaryngoscopes These are rigid devices that allow visualization of the vocal cords and related airway structures not in direct line of sight. Its combined use is well known in recent years [25] and different devices have been combined for this use. Initially, it was the Airtraq device [25 - 27] (Fig. 11) and later King Vision [28, 29], both described in the literature.

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Fig. (9). Fibreoptic guided tracheal intubation through Supraglottic Airway Device (SAD) using Aintree intubation catheter.

Fig. (10). DAS protocol for Fibreoptic guided tracheal intubation through Supraglottic Airway Device (SAD) using Aintree intubation catheter (https://das.uk.com/files/AIC_abbreviated_Guide_Final_for_ DAS.pdf).

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Fig. (11). Awake intubation with Airtraq & aScope.

They limit the blind point of advancing the ETT through the vocal cords over the FIS, very useful, for instance, in the management of giant laryngeal cyst [29]. In this manoeuvre, a videolaryngoscope is used as a guide for the flexible scope intubation device (as a “video oral airway accessory” before that an intubation device), and during the moment of sliding the ETT inside the vocal cords, the anaesthetist will have direct vision through the video laryngoscope. This combined technique is feasible with awake patients, necessitating maximum blocking of the airway. Patient's collaboration is mandatory, with adequate preparation, information to the patient and so on is being essential. CONTRAINDICATIONS INTUBATING SCOPE

AND

DISADVANTAGES

OF

FLEXIBLE

There are no absolute contraindications to FSI. Clinical situations in which it may be difficult or impossible are: ● ●

●

Blood or copious secretions in the airway. Need to observe the passage of the endotracheal tube (ETT) through the vocal cords as the ETT is passed blindly over the FIS. Troubleshooting making a combined use with a video-laryngoscope. Need for fast control of the airway.

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Clinician inexperience. Patient unable to cooperate (for awake FSI).

CONCLUSION ●

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The Fiberscope is still the most important DA device, all specialists need to handle it, since there are exclusive indications for its use. With the appearance of new Optical Devices, its use has diminished, as it is a fragile device that needs very rigorous care in its maintenance. Requires a long and systematized learning, first in mannequins and finally, in healthy patients relaxed and with local anaesthesia, ending in an awake patient with possible difficult intubation. The FBO is not substitutable in all circumstances, when it is necessary to perform a nasal intubation due to minimal opening of the mouth or an intubation with awake patient, it is irreplaceable (although nowadays there are more and more frequent publications of other devices with the awake patient), what you should know and know how to use.

CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that the contents of this chapter have no conflict of interest. ACKNOWLEDGEMENTS Declared none. REFERENCES [1]

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Frerk C, Mitchell VS, McNarry AF, et al. Difficult Airway Society intubation guidelines working group. Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults. Br J Anaesth 2015; 115(6): 827-48. [http://dx.doi.org/10.1093/bja/aev371] [PMID: 26556848]

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Matioc AA. Use of the Airtraq with a fibreoptic bronchoscope in a difficult intubation outside the operating room. Can J Anaesth 2008; 55(8): 561-2. [http://dx.doi.org/10.1007/BF03016679] [PMID: 18676394]

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Yuan YJ, Xue FS, Liao X, Liu JH, Wang Q. Facilitating combined use of an Airtraq® optical laryngoscope and a fiberoptic bronchoscope in patients with a difficult airway. Can J Anaesth 2011; 58(6): 584-5. [http://dx.doi.org/10.1007/s12630-011-9484-8] [PMID: 21431451]

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Gomez-Rıos MA, Nieto Serradilla L. Combined use of an Airtraq optical laryngoscope, Airtraq video camera, Airtraq wireless monitor, and a fibreoptic bronchoscope after failed tracheal intubation. Can J Anesth 2011; p. 58.

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El-Tahan MR, Doyle DJ, Khidr AM, Regal MA, El Morsy AB, El Mahdy M. Awake tracheal intubation with combined use of King Vision™ videolaryngoscope and a fiberoptic bronchoscope in a patient with giant lymphocele. Middle East J Anaesthesiol 2014; 22(6): 609-12. [PMID: 25669006]

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Sowers N, Kovacs G. Use of a flexible intubating scope in combination with a channeled video laryngoscope for managing a difficult airway in the emergency department. J Emerg Med 2016; 50(2): 315-9. [http://dx.doi.org/10.1016/j.jemermed.2015.10.010] [PMID: 26531708]

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CHAPTER 9

An Update on Awake Intubation Management María Luisa Mariscal Flores1,*, Claudia Palacios Muñoz1, Rocío Castellanos González1, María Jesús Jiménez Garcia1 and Sonia Martín Ventura1 Department of Anesthesiology and Critical Care Medicine, Hospital Universitario de Getafe, Madrid, Spain 1

Abstract: Local anesthesia in airway management allows orotracheal or nasotracheal intubation in awake patients with anticipated or known difficult airway predictors. Until a few years ago, the device that was used for awake intubation was the Fiberscope (FBO) but currently, in addition, you can use any airway device, as long as you effectively anesthetize the structures through which the device is inserted [1]. This requires adequate local anesthesia during the necessary time, waiting long enough for the local anesthetic to work in order to achieve quick and easy intubation with minimal or nil sedation, although other working groups use sedation during this procedure [2].

Keywords: Awake intubation, Airway management, Airway anesthesia, Airway topicalization, Airway nerve blocks, Awake fibreoptic bronchoscopy, Awake videolaryngoscopy, Difficult airway, Dexmedetomidine, Ketamine. INTRODUCTION In this chapter, local anesthetics and application techniques are described. Finally, the preparation of the patient to the FBO used in the hospital, University Hospital of Getafe, Madrid (HUG), is exposed [3]. Indications - Previous history of difficult intubation or ventilation. - Very obvious predictive signs of the difficult airway. Contraindications - Inexperience of the anesthesiologist. - Refusal of the patient. - Absence of patient collaboration. - Children or mental retardation. Corresponding author María Luisa Mariscal Flores: Department of Anesthesiology and Intensive Care, Hospital Universitario de Getafe, Madrid, Spain; Tel/Fax: 0034 916 83 93 60; E-mail: [email protected]

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- Allergy to anesthetics. - Massive bleeding from the mouth. LOCAL ANAESTHESIA Perform intubation with the patient awake requires adequate local anesthesia in all areas where devices used for intubation will be introduced (Fig. 1).

Fig. (1). Preparation for awake intubation procedure. Xilonibsa, VAMA cannula, Fiberscope, Magill tweezers, Lidocaíne and swabs.

Local Anesthetics Lidocaine This local anesthetic, used in the respiratory tract, is an amide derivative, with vasodilator properties and bitter taste. It can be found in cream and spray in 1%, 2%, 5% concentration and in 10% gel. In the upper airway, it is used at 5% and its lasts 30-60 minutes and has a latency of 2-4 minutes. 2% also is used, especially in children and the lower airway. Lidocaine absorption is lower in the upper than in the lower airway due to its lower surface area. The maximum dose of lidocaine for topical anesthesia in the respiratory tract is 3 mg/kg. In practice, doses up to 9.3 mg/kg have been used without systemic toxicity [4]. Although clinical experience with lidocaine has proven to be an effective topical agent with an ample safety margin, if the patient has a committed airway, topical anesthesia and airway manipulation can produce a complete obstruction and

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might be advisable to perform a tracheostomy with local anesthesia. Cocaíne It is an ester derivative and the only local anesthetic with vasoconstrictor properties, since it prevents the reuptake of Catecholamines by adrenergic nerve endings, increasing their levels in the blood and producing vasoconstriction. Used at the concentration of 5%, it acts at 3-5 min, has its maximum plasma peak after 60 min and is metabolized in 5-6 h. The recommended maximum dose of topical cocaine in the nasal cavity is 1.5-3 mg/Kg, with systemic absorption of 40% [5]. You should always use carefully in patients with hypertension, coronary heart disease, preeclampsia, and butyrylcholinesterase deficit. There are other local anesthetics such as benzocaine or tetracaine. Vasoconstrictor Agents [1, 3, 6, 7] The nasal mucosa is highly vascularized being able to bleed easily, so, before any operation, the use of local anesthetic with vasoconstrictor is required when topical anesthesia in the nose is performed. Oxymetazoline 0.1% It is a sympathomimetic used as a nasal decongestant spray or drops being as effective as cocaine to produce nasal vasoconstriction. If 5-10 drops (0, 5-1 ml) are used, mixed with 3 ml of lidocaine 5% and 3 ml of 2% lidocaine, we obtain good analgesic and vasoconstriction. Phenylephrine It is an alpha agonist powerful vasoconstrictor. HUG hospital uses a blend of 5% lidocaine (3 ml) and 2% lidocaine (3 ml) and Oxymetazoline (1 ml) in which four patties will be captured, two for each nostril. Local Anesthesia Techniques Topical Anesthesia The direct application of local anesthetic in the mucous membranes of the respiratory tract is the most common method, being easy and effective. There are different ways to perform this technique:

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● Direct application is to apply lidocaíne gel or spray on the floor of the tongue and oropharynx. ● Chiffons or pattie, are useful for applying cocaine or lidocaine with vasoconstrictor in the nasal cavity. A rhinoscope and special pliers are used to introduce the patties soaked with anesthetic at the bottom of the nasal cavity (lidocaine 2% 3 ml and 5% 3 ml and oxymetazoline 0.5 - 1ml). ● The local anesthesia should be deposited in the space that exists after the inferior turbinate along the floor of the nose up to the choana, anesthetizing the nose and part of the oropharynx depositing the anesthetic by gravity towards such structures. ● Spray as you go (SAYGO) consists of instilling the local anesthetic in the mucous membrane of the respiratory tract that moves with the FBO (Fig. 2). It is introduced through the working channel measuring 60 cm in length and 1.5 mm in diameter. 2 ml lidocaine 2% in 10 ml syringe is loaded and the rest is filled with air, thus leaving a mixture of lidocaine and air.

Fig. (2). Spray as you go (SAYGO).

In this way, a force majeure is created when the plunger is pressed and lidocaine drops to the distal part of the working channel almost in the form of a jet.

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Also, it can instill local anesthesia through an epidural catheter placed in the working channel. This maneuver normally requires an assistant. It can produce coughing and the dropped spray will cloud the vision by the FOB. It is necessary to manage or asking the patient for deep inspiration to regain good vision. Topical Glossopharyngeal nerve anesthesia by swab application, using lidocaine 5% (soaking the swab in a punt with 10 ml of anesthetic), enters the channel between teeth and tongue and pressing over the palatoglossus arch. The swab should be remain there for 1 minute approximately 3-4 times and repeat on the other side. Fogging The respiratory tract can be anesthetized with lidocaine through a nebulizer. The particles larger than 100 m will concentrate on the oral mucosa; those of 60-100 um into the trachea and main bronchi and the 60-30 um in the larger bronchi. In the nebulizer, there are 4-6 ml of lidocaine 5% and the O2 is released with flow of 8 liters per minute. The technique is easy, safe, non-invasive, and comfortable for the patient; cough is minimal or absent. It requires 20 to 30 minutes to get an adequate anesthetic level. Nerve Blocks It consists of the injection of a local anesthetic in the area of a nerve to anesthetize it. The airway is innervated by several cranial nerves and topical anesthesia is sometimes not enough to block some specific ones. It can be achieved by specifically blocking: -Palatine nerve (Sphenopalatine ganglion). - Glossopharyngeal nerve. - Superior laryngeal nerve. - Inferior laryngeal or recurrent nerve. It is important to know this technique because it is easy to prepare, fast-acting, and produces an intense blockage, although it presents a higher risk of complications than other ones and it must be always bilateral [6]. Techniques of Local Anesthesia in The Hospital Universitario de Getafe (HUG) The HUG awake intubation follows several consecutive steps described below,

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based on proper local anesthesia, adequate oxygenation, and minimal sedation for our patients [8, 9] (Figs. 3 and 4).

Preparation for awake intubation procedure. Xilonibsa, VAMA cannula, Fibroscope, Magil, Lidocaine, tweezers, swabs, laryngoscope, etc.

Nasal Topical anesthesia: 4 lentins impregnated in a solution of 3 ml. of lidocaine 5% + 3 ml. of lidocaine 2% + oxymetazoline 2 ml.

Oropharyngeal anesthesia: spray atomizer connected to syringe with 2 ml. of lidocaine 2%, divided into 2 puffs on the base of tongue and 2 side puffs. (can be repeated 2-3 times). If nausea persists → Swabs.

Fig. (3). HUG awake intubation protocol.

Nausea reflex valoration

Topical blockade of nausea reflex in anterior palatoglossal fold (glossopharyngeal): bilateral swab helped by laryngoscope (light and tongue displacement) soaked in lidocaine 5%, maintain 30 sg.-1 min. Repeat 3-4 times until the reflex is canceled (check with depressor). If nausea persists → Infiltration.

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Infiltration of the anterior palatoglossal fold: use spinal needle 22, cutting the plastic protector and leaving 0.5 cm free. Needle, connected to a syringe with 2 ml. of lidocaine 2%. Make small bilateral wheal.

Spray as you go (SAYGO) in glottis

Introduce the epidural catheter through the working channel of the FBO and, upon reaching the glottis, remove the catheter and administer 2 ml. of lidocaine 2% in syringe of 2 ml. Wait 3 minutes.

Spray as you go (SAYGO) in trachea Introduce the catheter into the trachea and administer 2 ml. of 2% lidocaine in a 2 ml syringe. The patient will probably cough. Wait 3 minutes. Insert the FBO up to 3-4 cm. over the carina and slide the endotracheal tube, confirm the intubation with capnography and proceed to general anesthesia.

Fig. (4). HUG awake intubation protocol.

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Sedation In our center, we try to use the minimum possible sedation, in most of the cases only 1-2mg of midazolam are administered. It is really important establishing a bond of trust with the patient, carefully explaining what the process will be and why it is done, and asking him his maximum collaboration. Administering topical anesthesia carefully, choosing the right anesthetic, dedicating enough time required, and achieving patient confidence are keys to success in awake intubation. Other authors use drugs for sedation such as opioids, hypnotics, and ketamine, alone or in combination. They should be carefully titled to maintain consciousness and patient spontaneous ventilation. Currently, dexmedetomidine is also used (bolus 1 microg/kg intravenously in 10 minutes, followed by an infusion of 0.20.7 µmg/Kg/h). The dose should be reduced in the elderly and patients with cardiac depression) [10 - 13] (Fig. 5). To evaluate sedation, the Ramsay scale is used, which assesses the degree of sedation depth from level 1, where the patient is alert, anxious, and agitated; to level 6 where the patient does not respond, so defining levels 1-3 as a patient "awake" and 4-6 as "asleep" [14, 15]. WHAT IS CHANGING CURRENTLY? Despite the fact that the audit NAP4 (2011) recommended the use of awake FBO in high-risk VAD patients [16], less and less is being used and the use of video laryngoscope (VDL) is being given way for its largest current use, shorter execution time, and easier implementation. To achieve awake intubation with VDL, the same techniques as those used with the FBO can be described [17]. These devices should not be considered mutually exclusive in the awake intubation of the patient but can be used together to optimize glottis vision and the proper position of the endotracheal tube. Despite this, it is necessary to continue learning and practicing with the FBO because there are some cases, such as limited mouth opening, in which nasal intubation with FBO is the only option. In the future, there will surely be written guides on awake intubation and the VDL will have their site.

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All the anesthesiologists should learn awake intubation with VDL as a fundamental skill in their usual work environment [18 - 20]. Awake Fiberoptic Intubation Adult Treatment Protocol Premedicate With Atropine 0,5-1 mg i.v Helps minimize aspiration risk by: • Reducing salivary, tracheobronchial and pharyngeal secretions. • Reducing volume and free acidity of gastric secretions. Atropine can also be used intraoperatively to counteract surgical, drug-induced or vagal reflexes associated arrhythmias and protect against peripheral muscarinic effects (e.g., bradycardia and excessive secretions) of cholinergic agents. Start Supplemental Oxygen by Nasal Cannula or Face Mask Infuse Dexmedetomidine infusion device.

with

a

controlled

In patients already sedated with other anesthetics, sedatives, hypnotics or opioid analgesics, a Dexmedetomidine loading dose may not be necessary. - Coadministration of anesthetics, sedatives, hypnotics and opioids with Dexmedetomidine can enhance the pharmacodynamic effects of these agents. - A reduction in the dosage of Dexmedetomidine or the concomitant medication may be required. - Patients receiving Dexmedetomidine may be arousable and alert when stimulated. - This alone should not be considered as evidence of lack of efficacy in the absence of other clinical signs and symptoms.

Prepare Dexmedetomidine: • Withdraw 200 mcg. • Add sodium chloride injection to total 50 mL. • Shake gently to mix well.

Expect Moderate Decreases in BP & HR if intervention is required, consider: • Reducing Dexmedetomidine dosage. • Discontinuing Dexmedetomidine. • Administering intravenous fluid. • Elevating lower extremities. • Administering Atropine.

Initiate Dexmedetomidine: • Loading Dose 1 mcg/kg over 10 min. After 10 min, continue Dexmedetomidine Maintenance Infusion at 0.7 mcg/kg/hr. Assess Sedation Level 15 min after initiating Dexmedetomidine and every 3 min thereafter.

Transient Hypertension also may occur: • This occurs primarily during the loading infusion. • Treatment has generally not been necessary, although reduction in the loading infusion rate may be desirable.

Undersedated: • Ramsay Sedation Score (RSS) = 1. • RSS 1 = Patient anxious and agitated or restless or both.

Adequately Sedated: • Target RSS 2 or 3.  RSS 2 = Patient cooperative, oriented and tranquil.  RSS 3 = Patient responds to commands only.

Administer 0.5 mg midazolam as needed (maximum 0.2 mg/kg) until RSS 2 or 3

Maintain Dexmedetomidine

Apply Airway Topical Anesthesia: • Deliver nebulized 4 to 6 mL of 5% lidocaine over 20-30 min using a standard nebulizer with oxygen 8 l/min. • If possible, have the patient gargle with 4% viscous lidocaine (1 to 2 ml) o 2 pufs Xilonibsa (10% lidocaine). • Prepare nasal intubation (always): 5% lidocaine (2 ml) + oxymetazoline within the nostril. • Assess sedation level (target RSS 2 or 3). Assess Topicalization: • Oral intubation: stimulate the uvula, tongue and bilateral posterior pharyngopalatine fauces with a wooden tongue Blade. • Nasal intubation: stimulate the posterior nares at least 3 cm from the anterior os with a soft-tipped swab stick in addition to stimulating the uvula, posterior tongue and bilateral posterior pharyngopalatine fauces with a wooden tongue Blade. Intubate the Patient After Adequate Topical Anesthesia, RSS 2 or 3 and Absence of Gag Reflex: • Administer additional 2% lidocaine (in 1 to 2 ml aliquots) to the lower airway via the working channel of the bronchoscope (airway topical anesthesia with a spray-as-you-go technique via the fiberoptic bronchoscope). • Ask the patient to take slow, regular and deep breaths to facilitate distribution of the local anesthetic to the lower airway. • Administer 0.5 mg midazolam as needed (maximum 0.2 mg/kg) until RSS 2 or 3.

Safety Considerations: • Hypotension and bradycardia may necessitate intervention and may be more pronounced in patients with hypovolemia, diabetes mellitus or chronic hypertension as well as in the elderly. • Use with caution in patients with advanced heart block or severe ventricular dysfunction.

Fig. (5). Protocol for Awake Fiberoptic Intubation in Adult with Dexmedetomidine (HR image: bit.ly/2OUA6wp).

CONCLUSION - Airway topical anesthesia is recommended as a technique of awake intubation. - The collaboration of the patient is very important, and therefore it is necessary to explain in a correct and simple language, describing the reason for it.

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- It is advisable to carry out the entire process with proper local anesthesia, which is the key to the success of the procedure. When the local anesthetic is used, you must be familiar with the speed of onset of action, duration, optimal concentration, maximum recommended dose, signs and symptoms of toxicity. It also requires adequate oxygenation and minimal sedation. - It is advisable to submit a report on the technique used and the reasons of their use to the patient or the family. CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that the contents of this chapter have no conflict of interest. ACKNOWLEDGEMENT Declared none. REFERENCES [1]

Hagberg C. Preparation of the patient for awake intubation. In: Hagberg and Benumof's Airway Management.Elselvier 2017; pp. 216-34.

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Hagberg CA, Artime CA. Airway management in the adult. In: RD Miller Miller’s Anesthesia. 8th ed. Philadelphia: Elsevier/Saunders 2015.

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Mariscal Flores ML, Martínez Hurtado E. Intubación en el paciente despierto. In: Mariscal Flores ML, Martínez Hurtado E. (Eds).Manual de manejo de la vía aérea difícil AnestesiaRorg. 2017; pp. 211-22.

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Daos FG, Lopez L, Virtue RW. Local anesthetic toxicity modified by oxygen and by combination of agents. Anesthesiology 1962; 23: 755-61. [http://dx.doi.org/10.1097/00000542-196211000-00004] [PMID: 14025067]

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Walsh ME, Shorten GD. Preparing to perform an awake fiberoptic intubation. Yale J Biol Med 1998; 71(6): 537-49. [PMID: 10604785]

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Jhon Doyle D. Topical and regional Anesthesia for tracheal intubation. Anesthesiology News 2014; pp. 9-13.

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Pani N, Kumar Rath S. Regional & topical anaesthesia of upper airways. Indian J Anaesth 2009; 53(6): 641-8. [PMID: 20640090]

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Patel A, Nouraei SA. Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE): a physiological method of increasing apnoea time in patients with difficult airways. Anaesthesia 2015; 70(3): 323-9. [http://dx.doi.org/10.1111/anae.12923] [PMID: 25388828]

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Law JA, Morris IR, Brousseau PA, de la Ronde S, Milne AD. The incidence, success rate, and complications of awake tracheal intubation in 1,554 patients over 12 years: an historical cohort study. Can J Anaesth 2015; 62(7): 736-44. [http://dx.doi.org/10.1007/s12630-015-0387-y] [PMID: 25907462]

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[10]

Hu R, Liu JX, Jiang H. Dexmedetomidine versus remifentanil sedation during awake fiberoptic nasotracheal intubation: a double-blinded randomized controlled trial. J Anesth 2013; 27(2): 211-7. [http://dx.doi.org/10.1007/s00540-012-1499-y] [PMID: 23073729]

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Sinha SK, Joshiraj B, Chaudhary L, Hayaran N, Kaur M, Jain A. A comparison of dexmedetomidine plus ketamine combination with dexmedetomidine alone for awake fiberoptic nasotracheal intubation: a randomized controlled study. J Anaesthesiol Clin Pharmacol 2014; 30(4): 514-9.

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Mingo OH, Ashpole KJ, Irving CJ, Rucklidge MW. Remifentanil sedation for awake fibreoptic intubation with limited application of local anaesthetic in patients for elective head and neck surgery. Anaesthesia 2008; 63(10): 1065-9. [http://dx.doi.org/10.1111/j.1365-2044.2008.05567.x] [PMID: 18673364]

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Eugenio DMH, Míriam SM, Gómez-Ríos MA, et al. Proposal for a protocol for awake fiberoptic intubation in adult with dexmedetomidine. SOJ Anesthesiol Pain Manag 2017; 4(2): 1-7. [http://dx.doi.org/10.15226/2374-684X/4/2/00145]

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Berning V, Laupheimer M, Nübling M, Heidegger T. Influence of quality of recovery on patient satisfaction with anaesthesia and surgery: a prospective observational cohort study. Anaesthesia 2017; 72(9): 1088-96. [http://dx.doi.org/10.1111/anae.13906] [PMID: 28510285]

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Dhasmana SC. Nasotracheal fiberoptic intubation: patient comfort, intubating conditions and hemodynamic stability during conscious sedation with different doses of dexmedetomidine. J Maxillofac Oral Surg 2014; 13(1): 53-8. [http://dx.doi.org/10.1007/s12663-012-0469-0] [PMID: 24644397]

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Cook TM, Woodall N, Frerk C, et al. The NAP4 report Major complications of airway management in the United Kingdom. London: The Royal College of Anesthesists 2011. http://www.rcoa. ac.uk/system/files/CSQ-NAP4-Full.pdf

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Alhomary M, Ramadan E, Curran E, Walsh SR. Videolaryngoscopy vs. fibreoptic bronchoscopy for awake tracheal intubation: a systematic review and meta-analysis. Anaesthesia 2018; 73(9): 1151-61. [http://dx.doi.org/10.1111/anae.14299] [PMID: 29687891]

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Wilson WM, Smith AF. The emerging role of awake videolayngoscopy in airway management. Anaesthesia 2018; 73(9): 1058-61. [http://dx.doi.org/10.1111/anae.14324]

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Marshall SD, Chrimes N. Time for a breath of fresh air: Rethinking training in airway management. Anaesthesia 2016; 71(11): 1259-64. [http://dx.doi.org/10.1111/anae.13665] [PMID: 27677258]

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Fitzgerald E, Hodzovic I, Smith AF. ‘From darkness into light’: time to make awake intubation with videolaryngoscopy the primary technique for an anticipated difficult airway? Anaesthesia 2015; 70(4): 387-92. [http://dx.doi.org/10.1111/anae.13042] [PMID: 25764402]

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CHAPTER 10

An Update on the Sedative Agents on Awake Intubation Maria Aliaño Piña1 and Miguel Ángel Fernández Vaquero1,* Department of Anesthesiology and Critical Care, Clínica Universidad de Navarra, Madrid, Spain 1

Abstract: The success of awake intubation depends on the ability of the anaesthesiologist and adequate sedation which promotes safe intubation in a cooperative patient. In order to achieve this, it is advisable to know the pharmacokinetics of the different drugs and choose those which you are more familiarised with.

Keywords: Awake fibreoptic intubation, Dexmedetomidine, Difficult airway, Fentanyl, Flexible bronchoscopy, Midazolam, Propofol, Remifentanil, Sedation, Sevoflurane, TCI. INTRODUCTION In this chapter, we will review the main sedative drugs used to perform awake intubation. The first fibreoptic intubation was described in 1967 by Murphy [1]. Since then, it has been the recommended technique for the management of the difficult airway in both anticipated and unknown airways. The awake fibreoptic intubation is the gold standard management of patients with an anticipated difficult airway; however, nowadays, awake intubation can also be performed with the aid of videolaryngoscopes [2]. In order to perform awake intubation, conscious sedation is necessary to make the procedure tolerable, preserve spontaneous ventilation, and maintain a patent airway. The goal is to allow the patient to be responsive and cooperative. This is only possible due to individualised sedation and appropriate local anaesthesia of the airway. Corresponding author Miguel Ángel Fernández Vaquero: Department of Anesthesiology and Intensive Care. Clínica Universidad de Navarra, Madrid, Spain; Tel/fax number 0034 913 53 19 20; E-mail: [email protected]

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SEDATIVE AGENTS There are different groups of drugs with sedative capacities. This chapter will focus on the agents that are most frequently used in the sedation of awake intubation. These groups are benzodiazepines, opioids, anesthetic inductors, and the alpha-2 agonist dexmedetomidine. The best sedative for awake intubation depends on the patients and their comorbidities, therefore, it will be necessary to individualize. Needs will be different in a patient with a difficult airway with respiratory distress from another with difficult airway and mental disorder or cervical spinal cord section. Ideal agents would provide anxiolysis, amnesia, analgesia, suppress cough and gag reflex, and be easy to titrate with minimal respiratory and cardiovascular side effects (Fig. 1).

Fig. (1). Awake intubation: Airtraq & FOB (full video: bit.ly/2vxNs9S).

When performing awake intubation, we need to consider standard monitoring and the administration of antisialogogue agents such as glycopyrrolate or atropine that will facilitate the procedure. Next, we will talk about the different groups of medicines, emphasizing the most representative examples.

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Benzodiazepines Midazolam Midazolam is the most commonly used among the benzodiazepines because of its rapid onset, short half-life, and ability to provide anterograde amnesia. It is usually administered in combination with other agents; for example, fentanyl, remifentanil, or propofol due to its amnesic properties. The recommended dose for this purpose is 0,03-0,05 mg/kg. It provides hemodynamic stability and the respiratory depression can be antagonized by flumazenil. Opioids Opioids are strong analgesics that in combination with pure sedatives can help to attenuate the intense nociceptive stimulation during awake intubation. In addition to sedation, opioids provide analgesia, depress laryngeal reflexes, and are antitussive. Moreover, they can improve the analgesia when the topic anaesthesia is not complete; for example, due to mucosal inflammation or excessive secretions. Side effects include respiratory depression and euphoria. Opioidinduced respiratory depression can be easily reversed with naloxone 1-5 µg/kg. Fentanyl Fentanyl is a rapid-acting and a short duration agent. It was commonly used in combination with midazolam for awake intubation before remifentanil was synthesized. The recommended dose is 1-1,5 µg/kg and supplementary doses of 10 µg can be administered in order to obtain the desired effect. Opioid rigidity is not a problem when fentanyl is administered in these low doses. Remifentanil Remifentanil is a potent and ultra-short-acting opioid with a context-sensitive half-time of three minutes and an elimination half-time of six minutes. It provides profound analgesia, suppresses airway reflexes, and has minimal effect on cognitive function. It is easy to titrate due to its pharmacokinetics and, nowadays, it is used as the primary agent or in combination with other agents for the awake intubation [3]. Remifentanil can be administered both manually and via TCI (target-controlled infusion). Machata et al. [4] designed a randomized trial in order to find the optimal dose of remifentanil. They administered a 0,75 µg/kg bolus + 0,075 µg/kg/min infusion to the lower dose group and 1,5 µg/kg bolus + 0,15 µg/kg/min infusion to the higher dose group. The higher dose group presented more

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respiratory depression and higher tolerance to the procedure; therefore, they recommended the lower dose. The use of TCI is associated with a lower incidence of complications compared with manual administration [5]. Target-controlled infusion allows the user to achieve a chosen predicted concentration rapidly and with minimal overshoot. The device uses a computer-controlled algorithm that considers the drug’s particular pharmacokinetics properties. Stable effect-site concentrations can be obtained rapidly and maintained for as long as desired. Song et al. [6] found that the estimated EC 95 of remifentanil needed for smooth nasotracheal fibreoptic intubation was 3.38 ng/mL when used in combination with midazolam and topical lidocaine. TCI remifentanil has also been compared to TCI propofol in this scenario. Rai et al. [7] concluded that remifentanil provides better conditions than propofol for awake intubation regarding intubation time and patient tolerance, although there was no difference in patient satisfaction scores. In addition, remifentanil presents more incidence of recall. In conclusion, remifentanil may provide a tolerable experience of awake fibreoptic intubation despite the high incidence of recall [6 - 8]. The incidence of recall can be decreased by concomitant use of midazolam or propofol. Its main benefits are the antitussive and analgesic properties which result in reduced coughing and tracheal tube tolerance during intubation. Hypnotics Propofol Nowadays, propofol is the mostly used hypnotic worldwide. It has a short half-life without accumulation. It can be administered in bolus, manual infusions, and TCI. Diverse studies have been published regarding its use for sedation in awake intubation; its main benefit is being the low incidence of recall. The combination of propofol and remifentanil provides less incidence of coughing and better intubation conditions [3]. Reviewing the literature, it can be observed that over the last two decades, different concentrations of propofol have been used for awake intubation. The dose depends on the administration alone or in combination with other agents such as midazolam, fentanyl, or remifentanil. When choosing manual infusion administration, a recommended dose could be a bolus of 1 mg/kg followed by an infusion of 2 mg/kg/h and titrate to obtain the desired effect. It is important to note that for tolerable awake intubation, the required dose of propofol may be higher than for another purpose. Target-controlled infusion is a good option for induction under spontaneous

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ventilation. However, there is no clear consensus on the rate range. Knolle et al. [9], in their retrospective study, concluded that the plasma concentration for nonresponsiveness was 2,8 µg/ml. They used alfentanil but no local anaesthetic. On the other hand, the mean target plasma concentration with TCI propofol used in the study of Rai et al. [7] was 1,3 µg/ml. In this study, they also administered midazolam depending on the patient´s weight. This led to the belief that the concentration of propofol is highly dependent on the use of concomitant drugs. The risk of oversedation increases with effect-site concentrations higher than 33.5 µg/ml. Sevoflurane The use of sevoflurane for the management of a difficult airway was documented in the late 90s with different cases published in that time [10, 11]. This inhalational agent provides safe conscious sedation and maintenance of spontaneous ventilation and quick reversal of anaesthetic effects. The induction can be started at 4% with increasing concentrations of 1% until there is no reaction during mandibular manipulation. The sevoflurane allows good fibreoptic conditions with a progressive induction and low rates of desaturation [12]. The concomitant use of midazolam or fentanyl may decrease the minimum alveolar concentration. Sevoflurane may be the elective agent for children with difficult airways. The drawbacks of using sevoflurane are the excitation stage and the fact that it contaminates the environment. Dexmedetomidine Dexmedetomidine is a selective alpha-2-adrenoceptor agonist that can cause sedation, anxiolysis, analgesic sparing, reduced salivary secretion and minimal respiratory depression (Fig. 2). It has become very popular in the last decade for sedation in critical patients and for the management of the difficult airway. It has shown to reduce patients’ discomfort. However, to date, it has not demonstrated better awake intubation conditions when compared with other agents such as remifentanil or propofol [13 - 15]. It is usually administered as a slow 0.7-1.0 µg/kg bolus over ten minutes, followed by a 0.3-0.7 µg/kg/h infusion [15 - 17] (Table 1). Habitual dosage (see Table 1): ● ● ●

Initial dose: 0.7 mcg/kg/hr. Dosage range: 0.2-1.4 mcg/kg/hr. Usual dose: 0.5 mcg/kg/hr.

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Fig. (2). Physiology of the α2-adrenoceptor agonists receptor [15]. Table 1. Calculate IV rate as mL/hr. of Dexmedetomidine as a function of the weight and dose administered (bit.ly/2P1TMyf) [15]. Weight (kg)

Dosage (mcg/kg/h) 0.2 0.4 0.5 0.6 0.7 0.8 1.0 1.2 1.4

40

0.4 0.7 1 1.1 1.3 1.5 2 2.4 2.8

45

0.5 0.8 1.1 1.3 1.5 1.7 2.2 2.6 3.2

50

0.5 1 1.2 1.5 1.7 2 2.5 3 3.4

55

0.6 1.1 1.5 1.6 2 2.2 2.8 3.3 3.8

60

0.6 1.2 1.5 1.8 2.1 2.4 3 3.5 4.2

65

0.7 1.3 1.6 2 2.3 2.6 3.2 4 4.5

70

0.7 1.4 1.7 2.2 2.5 2.8 3.5 4.2 4.8

75

0.8 1.5 1.8 2.2 2.6 3 3.8 4.5 5.2

80

0.9 1.5 2 2.5 3 3.3 4 4.8 5.5

85

1 1.8 2.2 2.6 3.1 3.5 4.2 5

6

90

1.1 1.9 2.3 2.7 3.2 3.6 4.5 5.4 6.2

95

1.1 2 2.5 2.9 3.4 3.8 4.8 5.6 6.5

100

1.2 2.2 2.6 3 3.5 4

5

6

IV rate (ml/h)

7

Drug presentations in our hospital are Ampoules of 2 ml, with 100 mcg/ml (200 mcg per ampoule), or 10 ml ampoules with 100 mcg/ml (1000 mcg per ampoule = 1 mg).

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Dilution Table 1: 1 ampoule of 10 ml (1,000 mcg = 1 mg) in 40 ml of sodium chloride (50 mL total = 20 mcg/ml = 0.002 mg/ml). Adjust the dose to achieve a Ramsey Sedation Scale (RSS) [18] of 2 - 3. 1. Start the infusion at 1 mcg/kg/h (2- 5 ml/hr) over 10 min (Loading Dose). 2. After 10 min, continue at 0.7 mcg/kg/hr (1.3 - 3.5 ml/h) (Maintenance Infusion). 3. After 5 min (15 min after initiating infusion) and every 3 min there after Assess Sedation Level. Target Ramsey Sedation Scale (RSS): 2 - 3: a. Usual dose 0.5 mcg/kg/hr (1-2.6 ml/h). b. Usual dosage range: 0.4 -0.7 mcg/kg/hr (0.7 - 3.5 ml/hr). c. Do not exceed the dose of 1.4 mcg/kg/hr (2.8 - 7 ml/hr). The disadvantages of dexmedetomidine could be the relatively long loading time of the first dose, bradycardia, and hypotension. Caution should be exercised when administering Dexmedetomidine to patients with advanced heart block and/ or severe ventricular dysfunction. Because Dexmedetomidine decreases sympathetic nervous system activity, hypotension and/or bradycardia may be expected to be more pronounced in patients with hypovolemia, diabetes mellitus, or chronic hypertension and in elderly patients [19]. In terms of adverse reactions, rates observed in the clinical trials of a drug cannot be directly compared to rates in studies of another drug, and may not reflect the rates observed in practice. Use of Dexmedetomidine has been associated with the following serious adverse reactions: ● ●

Hypotension, bradycardia, and sinus arrest. Transient hypertension has been observed primarily during the loading dose in association with the initial peripheral vasoconstrictive effects of Dexmedetomidine.

Contraindications ● ● ● ●

●

Hypersensitivity to Dexmedetomidine. Second or third-degree AV block without a pacemaker. Bradycardia < 55 bpm. Fluid refractory hypotension and need for noradrenaline at doses> 0.5 mcg/kg/minute. Dysautonomia (e.g. spinal cord injury).

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Table 2. Resume of the pharmacokinetics properties. Sedatives

Pharmacological Actions

Midazolam

Anxiolysis, amnesia

Fentanyl

Analgesia, sedation

Remifentanil

Propofol

Doses for AI

anterograde 0,03-0,05 mg/kg/iv

Onset Time

Duration

Side Effects

1-3 min 13-30 min

Respiratory depression

1-1,5 µg/kg/iv

1-3 min

15-20 min

Respiratory depression

Analgesia, sedation

0,025-0,1 µg/kg/min TCI: 3-5 ng/ml

1-3 min

5-10 min

Respiratory depression

Sedation

1 mg/kg 2 mg/kg/min 1 min TCI: 2-3,6 µg/ml

5-10 min

Respiratory depression

Anxiolysis, sedation, 1 µg/kg bolus+ Dexmedetomidine analgesia, antisialogogue, 15 min 0,3-0,7 µg/kg/h simpaticolitic AI: awake intubation; TCI: target-controlled infusion.

Bradycardia hypertension

CONCLUSION ●

●

●

Awake fiberoptic orotracheal intubation (AFOI) is used in patients with expected difficult airways. Adequate sedation techniques are important during the procedure in order to maintain the patient’s airway and minimize discomfort. Drugs commonly used for sedation during awake intubation tend to be either primarily anxiolytic or analgesic, although some newer agents demonstrate both properties. The ideal choice of the drug may vary depending on the patient and the indication for AFOI. Awake intubation used to be underused, and increased use requires improvements in training.

CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that the contents of this chapter have no conflict of interest. ACKNOWLEDGEMENTS Declare none.

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REFERENCES [1]

Murphy P. A Fibre-optic endoscope used for nasal intubation. Anaesthesia 1967; 22(3): 489-91.

[2]

Gaszyński T. The use of the C-MAC videolaryngoscope for awake intubation in patients with a predicted extremely difficult airway: case series. Ther Clin Risk Manag 2018; 14: 539-42. [http://dx.doi.org/10.2147/TCRM.S150536] [PMID: 29559790]

[3]

Can J Anesth/J Can Anesth. 2013; 60: 584-99.

[4]

Machata AM, Gonano C, Holzer A, et al. Awake nasotracheal fiberoptic intubation: patient comfort, intubating conditions, and hemodynamic stability during conscious sedation with remifentanil. Anesth Analg 2003; 97(3): 904-8. [http://dx.doi.org/10.1213/01.ANE.0000074089.39416.F1] [PMID: 12933427]

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Moerman AT, Herregods LL, De Vos MM, Mortier EP, Struys MM. Manual versus target-controlled infusion remifentanil administration in spontaneously breathing patients. Anesth Analg 2009; 108(3): 828-34. [http://dx.doi.org/10.1213/ane.0b013e318198f6dc] [PMID: 19224790]

[6]

Song JW, Kwak YL, Lee JW, Chang CH, Kim HS, Shim YH. The optimal effect site concentration of remifentanil in combination with intravenous midazolam and topical lidocaine for awake fibreoptic nasotracheal intubation in patients undergoing cervical spine surgery. Minerva Anestesiol 2012; 78(5): 521-6. [PMID: 22240620]

[7]

Rai MR, Parry TM, Dombrovskis A, Warner OJ. Remifentanil target-controlled infusion vs propofol target-controlled infusion for conscious sedation for awake fibreoptic intubation: a double-blinded randomized controlled trial. Br J Anaesth 2008; 100(1): 125-30. [http://dx.doi.org/10.1093/bja/aem279] [PMID: 18037667]

[8]

Puchner W, Egger P, Pühringer F, Löckinger A, Obwegeser J, Gombotz H. Evaluation of remifentanil as single drug for awake fiberoptic intubation. Acta Anaesthesiol Scand 2002; 46(4): 350-4. [http://dx.doi.org/10.1034/j.1399-6576.2002.460403.x] [PMID: 11952431]

[9]

Knolle E, Oehmke MJ, Gustorff B, Hellwagner K, Kress HG. Target-controlled infusion of propofol for fibreoptic intubation. Eur J Anaesthesiol 2003; 20(7): 565-9. [http://dx.doi.org/10.1097/00003643-200307000-00009] [PMID: 12884991]

[10]

Kandasamy R, Sivalingam P. Use of sevoflurane in difficult airways. Acta Anaesthesiol Scand 2000; 44(5): 627-9. [http://dx.doi.org/10.1034/j.1399-6576.2000.00523.x] [PMID: 10786753]

[11]

Mostafa SM, Atherton AMJ. Sevoflurane for difficult tracheal intubation. Br J Anaesth 1997; 79(3): 392-3. [http://dx.doi.org/10.1093/bja/79.3.392] [PMID: 9389864]

[12]

Bonnin M, Therre P, Albuisson E, et al. Comparison of a propofol target-controlled infusion and inhalational sevoflurane for fibreoptic intubation under spontaneous ventilation. Acta Anaesthesiol Scand 2007; 51(1): 54-9. [http://dx.doi.org/10.1111/j.1399-6576.2006.01186.x] [PMID: 17073850]

[13]

He XY, Cao JP, He Q, Shi XY. Dexmedetomidine for the management of awake fibreoptic intubation. Cochrane Database Syst Rev 2014; (1): CD009798. [http://dx.doi.org/10.1002/14651858.CD009798.pub2] [PMID: 24442817]

[14]

Tsai CJ, Chu KS, Chen TI, Lu DV, Wang HM, Lu IC. A comparison of the effectiveness of dexmedetomidine versus propofol target-controlled infusion for sedation during fibreoptic nasotracheal intubation. Anaesthesia 2010; 65(3): 254-9. [http://dx.doi.org/10.1111/j.1365-2044.2009.06226.x] [PMID: 20105150]

[15]

Eugenio DMH, Míriam SM, et al. Proposal for a protocol for awake fiberoptic intubation in adult with dexmedetomidine. SOJ Anesthesiol Pain Manag 2017; 4(2): 1-7.

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[http://dx.doi.org/10.15226/2374-684X/4/2/00145] [16]

Abdelmalak B, Makary L, Hoban J, Doyle DJ. Dexmedetomidine as sole sedative for awake intubation in management of the critical airway. J Clin Anesth 2007; 19(5): 370-3. [http://dx.doi.org/10.1016/j.jclinane.2006.09.006] [PMID: 17869990]

[17]

Hagberg CA, Lam NC, Abramson SI, Vahdat K, Craig J. Dexmedetomidine vs. remifentanil for sedation in awake intubations. A randomized, double-blind trial. Anesthesiology 2008; 109: A14.

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Ramsay MA, Savege TM, Simpson BR, Goodwin R. Controlled sedation with alphaxalonealphadolone. BMJ 1974; 2(5920): 656-9. [http://dx.doi.org/10.1136/bmj.2.5920.656] [PMID: 4835444]

[19]

Dexmedetomidine hydrochloride injection, for intravenous use. Initial U.S. Approval 1999.

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133

CHAPTER 11

An Update on Paediatric Airway Management Gema Pino Sanz1,* and María Dolores Méndez Marín1 Department of Pediatric Anesthesiology, Hospital Universitario Doce De Octubre, Madrid, Spain 1

Abstract: The condition of “cannot intubate cannot ventilate” is very rare and stressful scenario in paediatric patients, requiring a deep knowledge about anatomic and physiologic features as well as their congenital anomalies. Their anatomical differences as compared to adults imply different laryngoscopy techniques and, for this reason, the endotracheal tube placement is more difficult than in adults. Moreover, paediatric patients have increased oxygen consumption and a reduced functional residual capacity, so the apnea time decreases considerably. In healthy infants under the age of 6 months, with the previous preoxygenation, the saturation pulse oximetry reaches 90% in 90 seconds, while in adults, it happens at 6 minutes [1]. The respiratory events are very common in the paediatric population during general anaesthesia induction. There are some risk factors such as age of under 12 months and the experience and skills of the anaesthesiologist [2]. The hypoxemia (airway management) is one of the causes of cardiac arrest in the operating-room (27%), while failed endotracheal intubation appears in 7% of the cases [3]. All paediatric anaesthesiologists should be warned about the anatomical and physiological characteristics of the paediatric airway [4].

Keywords: Combitube, Cricoid pressure, EC position, Extubation, Flexible fiberoptic bronchoscope, Functional residual capacity, Gastric distension, Laryngeal braking, Laryngeal mask airway, Laryngospasm, Light wand, Miller laryngoscope, Sniffing position, Lemon score , Sugammadex, Two hands ventilation, Uncuffed ETT, Videolaryngoscopy. AIRWAY ANATOMY The anatomical differences between adults and children decrease as the child grows to maturity. In Table 1, the significant characteristics are shown. The head and the prominent occiput are relatively large with respect to the rest of the body and, a supine position, the neck flexion can produce airway obstruction [5]. The nasal passages are narrower due to lymphoid tissues, increasing the airway resistance. Corresponding author Gema Pino Sanz: Department of Pediatric Anesthesiology, Hospital Universitario Doce De Octubre, Madrid, Spain; Tel/Fax:0034 913 90 80 00; E-mail:[email protected] *

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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The hypertrophy of lymphoid tissues in the pharynx can result in airway obstruction when sleeping (obstructive sleep apnea) and in performing laryngoscopy. In addition, the tongue is large and sticks to the palate, causing airway obstruction [6]. The elevation of the head to the “sniffing position” can improve this airway obstruction [1, 7]. The pediatric larynx has a cylindrical shape, not conical as it was assumed, and with an anterior diameter bigger than the transverse diameter. The cricoid ring is the most rigid area and the narrowest airway is in the subglottic area. These characteristics explain the inadequate seal of the uncuffed endotracheal tube (ETT) and do not prevent the ischemic damage caused by the pressure of the lateral walls [8, 9]. The larynx is situated more cephalad (C4) in newborns and then becomes caudal until level C6-C7 in adults [7]. The small cross-sectional area of the infant’s airway increases exponentially the resistance of the airflow; hence it can worsen the breathing. Epiglottis is relatively long and stiff. It is positioned more horizontal than in adults. In neonates, it is V-shaped and mobile, so a straight-blade laryngoscope is recommended because it can raise the epiglottis with the tip of the blade and improve the endotracheal intubation. At the age of 4- 5 years, the epiglottis is less mobile and smaller and the curve-blade laryngoscope is recommended. The larynx is situated more cephalad and anteriorly, so this creates an acute angle between the base of the tongue and the larynx; therefore, it is recommended to insert a roll under the shoulder, limiting the excessive flexion and improving laryngoscopy view. AIRWAY PHYSIOLOGY The pediatric airway has greater compliance while the connective tissue is poor, leading to a dynamic collapse in case of obstruction. If there is an extra-thoracic obstruction, the collapse occurs during the inspiratory phase, but if there is an intrathoracic disease, the collapse happens during the expiratory phase. The lung volumes of the children are similar to those of adults, except for the functional residual capacity (FRC), which increases as children grow. This smaller FRC tends to lung collapse, but there are compensatory mechanisms to avoid it, such as rapid respiratory rate, expiration control (“laryngeal braking”) and the tonic activity of the ventilatory muscles. This mechanism is blocked during sleep and general anesthesia.

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Table 1. Paediatric Airway Anatomy. Anatomy

Implication

Management

Prominent occiput Nares small Neck short Lymphoid tissue

Neck flexed in supine position Upper airway obstruction Oral/pharyngeal/laryngeal axes not lined up Laryngoscopy difficult

Shoulder roll Sniff position

Cephalad larynx Large tongue to mouth size

Larynx view more anterior Entire tongue in the oral cavity

Lateral approach to laryngoscopy

Epiglottis angled projecting above the glottic opening Larynx cylinder [10] Vocal cords slanted anteriorly and rostrally Narrow subglottic area

Epiglottis obstructs the view of vocal cords Straight laryngoscope blade < 3 years old Air leak Several intubation attempts

Cuffed endotracheal tubes

Moreover, during anesthesia, the collapse of the upper airway can occur due to the relaxation of the muscles of the soft palate, the base of the tongue and the uvula. In infants and neonates, the ETT can be shifted by manoeuvres e.g., putting a roll under the shoulder, the Trendelenburg position, the gastric distension, flexing or extending the neck, etc [11]. The ETTs have marks that, located at the vocal cords level, indicate the endobronchial intubation or extubation positions (only for children older than two) [12, 13]. CLINICAL SITUATIONS OF EXPECTED DIFFICULT AIRWAY All clinical situations of the expected difficult airway are summarized in Table 2. The craniofacial malformations are frequent and, due to pediatric growing, airway management could be improved or degraded with time. These anatomical anomalies can affect bones and soft tissues in different areas. FACE MASK VENTILATION The correct position of the facial mask, with an appropriate size, should provide adequate ventilation without disturbing structures. Sometimes-anesthesiologists can produce airway obstruction caused by tongue shift or vascular compression. The facial mask should be placed following the “EC position” rule: the thumb and the index finger of the left hand form a “C” around the hole of the mask, and the remaining three fingers form an “E” between the jaw angle and the anterior area (Fig. 1). During mask ventilation, the bag should be pressed until the thorax is elevated,

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allowing that the expiration time takes twice the inspiration time. In this way, the gastric distension does not appear [7, 12, 14]. Table 2. Associated congenital malformations to Difficult Airway (DA). Naso-Pharynx Tongue Maxillary Laryngx Trachea Cervical Spine CONGENITAL Choanal atresia Encephalocele Hemangioma Laryngomalacia Glottic membrane Stenosis subglottic S,Pierre-Robin S. Goldenhar S. Apert, S.Treacher-Collins, S.Turner, Achondroplasia, S. Cornelia de Lange, S. Smith-Lemli-Opitz, S. Hallermann-Streiff S. Down S. Kippel-Feil, Congenital torticollis Tracheomalacia Stenosis tracheal Anbomalities vascular

** **

** ** **

TRAUMA Airway foreign body Burn Laceration

** ** **

** **

INFLAMMATORY Adenoid/tonsilar inflammation Epiglotitis Juvenil arthritis Pharyngeal abscess

**

METABOLIC S.Beckwith-Wiedemann Mucopolysaccharidosis Morquio Gangliosidois Glucogenosis

** ** ** ** **

** ** ** ** ** ** ** ** **

**

** ** ** ** **

** ** **

** ** ** **

** ** **

** ** **

**

** ** **

**

**

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Fig. (1). “EC position” facial mask fastening.

Manual ventilation should be improved with the subluxation of the temporomandibular joint or with the ventilation with two hands. Capnography confirms adequate ventilation [15] (Table 3). Table 3. Causes of airway obstruction and treatment. Cause

Treatment

Inadequate head position

Repositioning head

Poor facemask technique

Reopening airway (chin lift, jaw thrust)

Large adenoids, tonsils, obesity

Oro/nasopharyngeal airway

Overinflated stomach

Gastric drain

Foreign body, gastric content, blood

Direct laryngoscopy to remove the foreign body

Laryngospasm

Deepen anesthesia (propofol) Two-person bag-facemask ventilation Muscle relaxation

Muscle rigidity

Deepen anesthesia

PREDICTORS OF DIFFICULT AIRWAY The incidence of difficult intubation in pediatric patients ranges from 0.1% to 0.35% [16], being this rate increased for children younger than 1-year, low

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weight, ASA III-IV and congenital heart disease [17]. However, the incidence is lower than in adults. The patient's history and his physical examination can help us predicting the difficult airway. Pediatrics patients do not collaborate, so the parameters to be considered are the size and position of the jaw and the facial features. Mallampatti classification system can be applied in children between 4 and 8 years old. The LEMON score for predicting a difficult airway in adults is not yet accepted for pediatric use [18]. Even though this score can be useful in some situations: ● ●

● ●

●

L: Look externally for indicators of a difficult airway. E: Evaluate mouth opening, thyromental distance, mandible distance and thyroid cartilage. M: Mallampati score. O: Obstruction signs airway: stridor, muffled voice, difficulty handling secretions. N: Neck mobility.

RAPID SEQUENCE INDUCTION The concept of the rapid sequence induction is to achieve secure airway by tracheal intubation in the shortest possible time after anesthesia induction, in order to prevent aspiration of gastric content. This particular anesthesia condition involves preoxygenation, drugs for rapid induction agent and muscle relaxant, cricoid pressure and sitting position. In pediatric anesthesia, rapid sequence induction has demonstrated a high rate of cardiorespiratory complications (hypoxemia, bradycardia and difficult endotracheal intubation), in particular when it is not performed by expert pediatric anesthesiologists. There is a modification of this technique, which consists of maintaining face mask ventilation during the procedure. This adjustment decreases the complications in children. The sequence requires a standard patient monitoring and intravenous access should be established prior to anesthesia induction. There are different induction agents (propofol, ketamine, midazolam or etomidate) according to clinical status and the use of a non-depolarizing muscle relaxant to secure an adequate paralysis prior to tracheal intubation is mandatory. Moreover, external stimuli to induce cough or vomit should be avoided. Cricoid pressure is not recommended because it distorts the airway, resulting in difficult ventilation and intubation. In infants, the ventilation should be kept during anesthesia induction, because apnea time is shorter than in adults, even if a correct preoxygenation is

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administrated. The face mask ventilation, performed with 100% oxygen and a limited pressure of 10 cm of water, decreases the severe hypoxemia, the bradycardia and the difficult tracheal intubation, without increasing the gastric aspiration risk [19 - 23]. SUPRAGLOTTIC AIRWAY DEVICES These devices are designed for ventilation and oxygenation and they are placed without entering into the larynx. These devices can be supraglottic as the laryngeal mask airway (LMA) or the Combitube, which has an entry into the esophagus. The classic Laryngeal Mask Airway (LMA) is the reference for other devices (Table 4). The LMA has demonstrated efficacy in emergency situations as cardiac arrest and in the management of the difficult airway. In this situation, LMA is a rescue device for ventilation and can be used as a conduit for fiberoptic endotracheal intubation. Actually, the LMA is incorporated in pediatric difficult airway algorithms. The LMA is relatively easy to insert in 90% of the patients, except for patients below 10 Kg of weight, where incorrect positions and complications are common [24 - 29]. Despite this fact, LMA can obtain adequate ventilation in less time than endotracheal intubation. LMA can be used as an alternative to tracheal intubation. The second generation of these devices provides access to evacuate gastric contents, better airway seal and more effective when used as a conduit for fiberoptic intubation.

The LMA has an easy learning curve if the following insertion is performed. LMA should be placed by a rotational movement and partially cuffed. In this way, there are fewer complications or misplacements and it is quicker than lateral or standard technique [30]. The removal of the LMA should be done under deep anesthesia to avoid cough and laryngospasm [31]. LARYNGOSCOPY AND TRACHEAL INTUBATION The laryngoscopy technique has several differences with respect to adult laryngoscopy. Anesthesiologists should consider the correct position of the head and neck, the use of a pillow-ring that aligns the airway and the glottis view, a careful

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examination of the teeth and the rise of the epiglottis with the tip of the straight blade for viewing the glottis. Table 4. Supraglottic Airway Devices (SAD). First Generation Supraglottic Airway

Simply Airway Device

Gastric Epiglottic Designed Drainage Downfolding Tracheal Tube Prevention Intubation

Limitations

cLMA

no

yes

no

Poor airway seal Mask displacement Gastric insufflation

fLMA

no

yes

no

Poor airway seal Mask displacement Gastric insufflation

Cobra Perilaryngeal Airway

no

yes

no

Unique LMA

no

yes

no

Second Generation Supraglottic Airway

Controlled Ventilation and Increased Airway Protection

Gastric Epiglottic Designed Drainage Downfolding Tracheal Tube Prevention Intubati0n

Poor airway seal Mask displacement Gastric insufflation Limitations

Proseal LMA

yes

no

no

gastric insufflation enable higher seal pressure

Laryngeal tube

yes

no

no

rate failure

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(Table 4) cont.....

i-gel

yes

yes

no

Spontaneous dislodgement

Supreme LMA

yes

yes

no

AIR-Q

no

yes

yes

Not blind Intubation in children

AURA-i

no

no

yes

Not blind Intubation in children Size 1,5 not cuffed tracheal tubes

AuraGain

yes

no

yes

No studies

There are two different types of direct laryngoscopes: Macintosh and Miller. The Miller laryngoscopes with a straight-blade are recommended for neonates and infants because they improve the glottis view, while the Macintosh laryngoscopes with a curve blade are commonly used for the older children. Both laryngoscopes are available in different sizes for all pediatric patients [6]. Traditionally, uncuffed ETTs are recommended for children up to eight years old. This is based on the anatomical peculiarities of the airways of young children in whom the circumferential and non-distensible cricoid cartilage is the narrowest point of the airway. Indeed, this can be narrowed with the formation of edema caused by trauma with an inappropriate size of the tube. However, uncuffed tubes are no longer the gold standard in pediatric airway management. Furthermore, there are tubes with high-volume low-pressure cuffed tubes such as the Microcuff tube. Despite the existence of formulas to choose the adequate ETT size, many times it is needed to change the tube for an appropriate one. The cuffed endotracheal tubes are preferred for major surgery with a high risk of aspiration and it is

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recommended to use a smaller tube size. These tubes may increase the risk of laryngeal and tracheal injury and post-extubation stridor. Recently, the results of this meta-analysis showed no evidence in the development of postextubation stridor in the children who received cuffed ETTs as compared to those receiving uncuffed ETTs [32]. ALTERNATIVE TECHNIQUES TO OPTIMIZE LARYNGOSCOPY The choice of device depends upon the specific obstacles to conventional endotracheal intubation during direct laryngoscopy, and upon the training and experience of the anesthesiologist in other devices. Currently, the Flexible Fiberoptic Bronchoscope (FFB) is the gold standard for difficult intubation, including patients who have limited opening mouth. New devices can have quicker preparation or availability, and can solve the management of the difficult airway. Some recommendations about the most appropriate device to be chosen depend on the clinical situation of the patient, as shown in Table 5. Nowadays, there are many different indirect laryngoscopy concepts in the market, but there is no evidence to support the superiority of one to the rest of them. Each device has its own recommendations for successful use [33]. The majority of the devices for difficult airway are based on indirect laryngoscopy, and can be classified into three groups: stylets, videolaryngoscopes (VL) or a combination of both. Table 5. Recommendations for airway device in Difficult Airway. Able to see epiglottis but not vocal cords

Intubation introducer (gum elastic bougie)

Unable to visualize the airway

Lighted stylet, fiberoptic stylet, flexible fiberoptic bronchoscope, indirect fiberscope, or video laryngoscope

Limited mouth opening or neck mobility

Lighted stylet, fiberoptic stylet, flexible fiberoptic bronchoscope, or indirect rigid laryngoscope

Videolaryngoscopy is a good alternative, easy to learn, and can replace the use of the FFB in some cases (emergency or elective). A metanalysis compared VL with direct laryngoscopy reporting fewer failed intubation when VL was used in the anticipated difficult airway [34]. Sometimes this technique provides a good glottis view but it is difficult to insert the tube (curved–blade). It is contraindicated when the opening mouth is limited. The DAS 2015 recommended that all anesthesiologists should be trained in using video-

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laryngoscopes [35]. Table 6 shows the most important videolaryngoscope types. The light wand intubation is a good technique for difficult airway. The endotracheal tube can be advanced into the trachea following a light path. This method requires practice but may be successful in difficult airway. It is limited by the size of the tube that can be passed over the stylet. This device should be used with caution when airway anatomy is not visible and it is possible to damage the larynx or the trachea. Table 7 shows different stylets.

Table 6. Videolaryngoscopes. Model C Trach

Pentax AWS

Photo

Characteristic

Inconvenient

Integrated channel Risk of remove laryngoscopes TET - Airway Laryngeal mask - Easy learning curve

Integrated channel laryngoscopes-Blade

Require mouth opening

Pediatric Use Yes

Yes

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(Table 6) cont.....

Model

Photo

Characteristic

Inconvenient

Pediatric Use

Airtraq

Integrated channel laryngoscopes-Blade - Easy learning curve

Require mouth opening Risk of TET damage (cuffed)

All pediatric sizes

Bonfils

Video Stylets-Rigid Easy learning curve Easy to prepare in emergency

Airway trauma Evidence in pediatric limited

V-MAC C-MAC

Rigid blade Laryngoscopes - Standard blade - Macintosh and Miller blade

Require mouth Neonates opening Pediatrics

Glidescope

Rigid blade Laryngoscopes - Angled blade

Require mouth Neonates opening Pediatrics

McGrath

Rigid blade Laryngoscopes-Angled Blade - To wrap(shape) the TET - Angled blade

Difficult to slide the TET

Table 7. Light Wand Types. Trachlight (two sizes)

ID: 4- 6 mm (child) ID:2.5-4 mm (infant)

Optical Stylet

ID > 2.5mm and videocamera–monitor to visualize the laryngeal inlet

ID: internal diameter tube

Pediatric blade for > 15 Kg

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GUIDELINE FOR THE UNEXPECTED DIFFICULT AIRWAY IN PEDIATRIC PATIENTS There are many guidelines for the assessment of difficult airway for adults but not enough for the pediatric patients. Most airway problems arise when unanticipated difficult tracheal intubation appears during a routine anesthesia induction [35]. The incidence of the unexpected difficult pediatric airway is lower than in adults and it can be predicted on many occasions. In some reviews the incidence of difficult mask ventilation is 2.8-6.6% [36] and of the difficult tracheal intubation is 0.06-1.34% [17, 36, 37]. All Pediatrics Anesthesiology Departments should have a specific guideline with the appropriate equipment (airway trolley) for unexpected difficult airway. Therefore, all anesthesiologists should be trained in all techniques that are available in their hospital for the management of the difficult pediatric airway. The learning curve should have been realized in ordinary procedures, so in this way, difficult airway management will be successfully accomplished in an emergency situation [38, 39]. The development of this guideline can improve the management of the difficult airway and allows decreasing the appearance of serious complications. This guideline should consider the following three important scenarios: difficult mask ventilation, unanticipated difficult tracheal intubation and the “cannot intubate - cannot ventilate” scenario with the surgical airway technique. The most important priority is always to maintain oxygenation during airway manipulation, calling immediately for help to another anesthesiology or ENT (ear, nose and throat) specialist. In pediatric patients, severe hypoxemia can lead to a cardiac arrest quicker than in adult patients. All anesthesiologists should be trained in techniques assuring ventilation and oxygenation in the difficult airway management (anticipated or not). These techniques are: one to two hands ventilation, nasotracheal intubation and insertion of a supraglottic airway device (SAD) [36]. The Association of Pediatric Anaesthetists of Great Britain and Ireland (APAGBI), the Difficult Airway Society (DAS) and expert pediatric anesthesiologists have designed specific national pediatric guidelines for the management of unanticipated difficult pediatric airway during routine anesthesia induction in children aged 1 to 8 years [40]. These guidelines are shown as the following text in three possible situations:

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Difficult Mask Ventilation During Anesthesia Induction (Fig. 2) Step A: It Considers Three Interventions to Check ●

●

Optimize head position: The manoeuvre of adjusting chin lift and jaw thrust is useful in all ages. In children under two years, the insertion of a roll under the shoulder and the lateral position may help to ventilate. The ventilation with two hands increases the peak inspiratory pressure and improves the ventilation, but the cricoid pressure is not recommended. Check the equipment again (before anesthesia induction, it should have been already checked).

The difficulty to maintain mask ventilation (MV) in children may be as high as 7%. In this situation, three important steps have to be followed. (https://www.das.uk.com/files/APA1-DiffMaskVent-FINAL.pdf). At this point, laryngospasm, gastric distension and lightening anesthesia as the causes of difficult ventilation should be ruled out. These should be solved before the next step.

Fig. (2). DAS - Difficult mask ventilation.

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Step B: Consider to Insert an Oropharyngeal Airway Device ●

●

Before inserting an oropharyngeal device, it is mandatory to deepen anesthesia with propofol and use continuous positive airway. The laryngospasm may have an incidence of 2% and it is more common on emergence than on routine anesthesia induction. The mild upper respiratory tract infection is one of the common causes of this situation in pediatric patients so it must be dismissed before the induction of anesthesia. The recommended initial management for laryngospasm is to provide CPAP with 100% oxygen and to deepen anesthesia by increasing the volatile anesthetic concentration.

It is suggested, when there is no intravenous access, that an intramuscular muscle relaxant should be given for this emergency situation. Suxamethonium was the classical option, but rocuronium at a dose of 1.2 mg/kg is effective in producing laryngeal relaxation in 30-60 sg. Rocuronium is increasing its clinical use in pediatrics and sugammadex has been shown effective in reversal paralysis. It is suggested that rocuronium is the most appropriate option because of no adverse effects. When the intravenous access is stablished, a bolus of propofol is the first line of strategy, maintaining the CPAP with oxygen 100% [42]. If this management does not allow to ventilate the patient, the use of muscle relaxants is accepted. The gastric distension is common in pediatric patients, and produces severe trouble in the diaphragm movement. It is recommended to insert an orogastric or nasogastric tube for avoiding this problem. If a muscular relaxant has been given, it is expected to facilitate the ventilation with a facial mask, being the tracheal intubation the next step to consider. Step C: Insert a Supraglottic Airway Device (SAD) ●

●

SADs (e.g., laryngeal mask airway) are the most appropriate second-line airway devices by a general consensus of pediatric anesthesiologists. The use of nasopharyngeal airway should be considered in the situation of insufficient mouth opening to insert an oropharyngeal airway or a SAD. More than 3 attempts of SAD insertion are not recommended. Generally, this device is successfully inserted, and it improves ventilation and oxygenation, so it is reasonable to continue with the procedure. If there is SAD malposition and the oxygen saturation of the patient is above 80%, a safe strategy is to wake up the patient. When it is impossible to place SAD correctly and to achieve a good oxygen saturation (SpO2< 80%), it is recommended to intubate after paralysis. Successful intubation allows going on with the procedure, and if intubation fails, this will lead to the scenario “cannot intubate, cannot ventilate” (CICV)

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Unanticipated Difficult Tracheal Intubation During Induction of Anesthesia in a Child Aged 1 to 8 Years (Fig. 3) Before tracheal intubation, the patient should be monitored (EKG, SpO2, PANI) with an intravenous access established and with an orogastric tube inserted. (https://das.uk.com/files/APA2-UnantDiffTracInt-FINAL.pdf). Step A: Initial Intubation Plan when MV is Satisfactory The anesthesiologist should call for help after the first failed intubation attempt and when the laryngoscopy is grade 3 or 4 in the Cormack-Lehane scale. The number of attempts at intubation should be four at total (two of them by an expert anesthesiologist). At this situation following steps should be considered: ●

●

●

●

●

●

Modify the head position for improving the laryngoscope view. External laryngeal manipulation does not improve this situation, differently than from adults. Change endotracheal tube size for using a smaller one or a cuffed tube that improves ventilation (not a consensus for children aged 1 to 3 years) and tracheal intubation. Laryngoscopes: there is no evidence that the use of the straight blade can improve the laryngoscope view. Newer indirect laryngoscopes (Airtraq, Glidescop es, Bullard, etc.) are widely used for children, but there is no evidence about which one is the most appropriate. The laryngoscopy offers a good view when there is deep anesthesia and paralysis. In this situation, an adequate paralysis of the vocal cords facilitates tracheal intubation. The possibility of blind intubation with a bougie in Laryngoscopes view 3-4 is not recommended in pediatric patients. Verification of intubation is required, and the capnography is the gold standard of monitoring. Sometimes the tube is progressed to the right bronchial unintentionally. If there is any doubt about the correct tube placement, the safer option is to remove it and maintain oxygenation via facemask.

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Fig. (3). DAS-Difficult tracheal intubation.

Step B: Secondary Tracheal Intubation Plan ●

●

●

In this situation of having adequate oxygenation but failed intubation, the next step should be to insert a SAD, but not in more than three attempts. Once the SAD allows adequate oxygenation and ventilation, the anesthetist can proceed safely with the surgery. If ventilation is not adequate, SAD should be changed for a larger one. If intubation is still necessary, fiberoptic intubation (FOI) via the laryngeal mask is the only secondary intubation technique supported by consensus [41]. If there is correct placement of SAD, adequate muscle relaxation and cardiovascular instability, one attempt of FOI via SAD is recommended in children aged 3 to 8 years. For children aged 1 to 3 years, this technique should be performed by a trained anesthesiologist. If the intubation is failed and the oxygenation is adequate, the safer option is to wake up the patient. If, after the placement of the SAD, there is inadequate oxygenation (SpO2 80% There is consensus in waking up the patient if oxygen saturation is 80% or greater and there is no hemodynamic compromise (e.g., bradycardia), but always a rescue subglottic access should be prepared in case the patient deteriorates the respiratory conditions. The reversal of neuromuscular blockade (sugammadex) cannot return to adequate spontaneous ventilation if there is upper airway obstruction, so the surgical airway should not be delayed.

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Step C: Airway Rescue Technique for CICV (SpO2< 80% and Failing) and/or Heart Rate Decreasing In this situation, a specialist ENT should be required immediately. If ENT is available, a surgical tracheostomy is recommended. In case the ENT is not available, the first line is to insert a percutaneous cannula cricothyroidotomy and jet ventilation (Fig. 5). This technique can have serious complications (emphysema, pneumothorax and barotrauma) and training is required [41]. Pediatric patients are more susceptible to these complications, so this should be carried out in life-threatening situations and converted into a definitive airway (tracheostomy) as soon as possible. Some experts suggest that percutaneous needle/cannula cricothyroidotomy or tracheostomy should not be used in children under 6 years old, preferring surgical airway [41]. In infants and neonates, the cricothyroid membrane is small and difficult to localize and the trachea is mobile, flaccid and easily compressible, so it is common to damage the posterior tracheal wall.

Fig. (5). Technique Percutaneous Cricothyrotomy.

EXPECTED DIFFICULT AIRWAY IN PEDIATRIC PATIENT (FIG. 6) The anticipated difficult airway in pediatric patients has a very low incidence (0.6%), so it is a very rare situation. In spite of this, it is recommended to anticipate the possibility of a difficult airway [43], and the predictors of the difficult airway should be considered previous to anesthesia induction [45]. The patient with an expected difficult airway should be transferred to a specialized center [36].

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Fig. (6). Pediatric Department Anesthesiology, Doce de Octubre – Madrid algorithm based on recommendations of DAS.

Pediatric patients do not allow awake endotracheal intubation because of the lack of collaboration. Inhalational anesthesia is considered the first option because it provides a good depth of anesthesia and keeps the spontaneous ventilation. Other possibilities of anesthesia drugs are ketamine, propofol, remifentanil and dexmedetomidine. CONCLUSION ●

●

●

●

●

In children, it is recommended to maintain spontaneous ventilation and adequate oxygenation; sometimes the use of SAD allows reaching this situation and maintaining general anesthesia for a safe surgery [36] The Flexible fiberoptic bronchoscopy (FFB) technique is the gold standard for difficult intubation and pediatric anesthesiologist should be trained to maintain skills in emergency situations [44]. FFBs are available in pediatric sizes and allow placing ETT for neonates and infants. The smaller FFBs do not have a suction channel. The Videolaryngoscopes can be an alternative for difficult tracheal intubation and can reduce the use of elective or emergency use of FFB. Videolaryngoscope technique is not possible if there is a limited opening mouth [37]. The surgical airway should always be always prepared for an emergency, and expert assistance should be required in the operating room. The extubation of a difficult airway should be planned, having prepared all the

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equipment for reintubation in advance. The patient should have totally recovered from anesthesia and with adequate ventilation. If there is any doubt about maintaining the clearance of the airway, it is recommended to leave a catheter a guide of a new reintubation [36]. CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that the content of this chapter has no conflict of interest. ACKNOWLEDGEMENTS Declared none. REFERENCES [1]

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Jagannathan N, Sequera-Ramos L, Sohn L, Wallis B, Shertzer A, Schaldenbrand K. Elective use of supraglottic airway devices for primary airway management in children with difficult airways. Br J Anaesth 2014; 112(4): 742-8. [http://dx.doi.org/10.1093/bja/aet411] [PMID: 24322570]

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Nykiel-Bailey SM, McAllister JD, Schrock CR, Molter DW, Marsh JK, Murray DJ. Difficult airway consultation service for children: steps to implement and preliminary results. Paediatr Anaesth 2015; 25(4): 363-71. [http://dx.doi.org/10.1111/pan.12625] [PMID: 25677176]

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CHAPTER 12

An Update on Obstetric Airway Management Mónica San Juan Álvarez1,*, Marta Chacón Castillo1, Adriana Carolina Orozco Vinasco1, María de la Flor Robledo1 and Concepción Rodríguez Bertos1 Department of Anesthesiology and Intensive Care, Hospital Universitario Severo Ochoa, Madrid, Spain 1

Abstract: Airway management in the obstetric patient is a challenge for anaesthesiologists, not only because of the anatomical and physiological changes during pregnancy, but also because of the surgery´s urgency, the location of the procedure, which sometimes takes place even outside the operation theatre, and also due to conflicts emerging between the needs of mother and foetus. The arising incidence in maternal comorbidities such as obesity, contributes to complications in airway management in this population.

Keywords: Airway management, Apnoeic times, Cricothyroid Membrane, Difficult airway, Difficult intubation, Laryngoscopy, Maternal death, Neuraxial anesthetic blocks, Predictors, Pregnant patient, Pregnancy, Pre-eclampsia, Ultrasonography, Videolaryngoscopy. INTRODUCTION Among pregnant patients, the incidence of difficult intubation is around 1.3%16.3% and of failed intubation is 1:250-1:300 general anaesthesia, which is at least ten times greater than in the general population [1, 2]. Nowadays, the number of caesarean sections performed under general anaesthesia is decreasing, and thus are the learning opportunities for new anaesthesiologists and trainees. Quinn et al found that the incidence of difficult intubation is 2.5 times greater among trainees than experienced anaesthesiologists [3]. Morbidity and mortality related to airway management in obstetric patients differ from the rest of the surgical population due to the fact that there are two patients at risk, the mother and the foetus. The most frequent cause of morbidity and mortality related to anaesthesia, in this setting, is failure or difficulties in airway Corresponding author Mónica San Juan Álvarez: Department of Anesthesiology and Intensive Care, Hospital Universitario Severo Ochoa, Madrid, Spain; Tel/Fax: 0034 914 81 80 00; E-mail: [email protected] *

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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control after general anaesthesia induction. This is the main reason why, general anaesthesia is being progressively abandoned favouring regional anaesthesia, reserving the first for selected cases, which are mostly non-elective caesarean sections [4, 5]. In the USA, the rate of maternal death related to anaesthesia is 1.6%, and this cause ranks in the seventh place of all maternal death causes [6]. In the UK, complications related to anaesthesia are also the seventh cause of maternal death, causing almost 3% of all deceases [7]. Kinsella et al reviewed literature over a 45year period, finding a maternal death due to an intubation failure ratio of 1:90. Hypoxaemia and aspiration were found to be the main causes of mortality. The authors reported incidences of 3,4 cricothyroidotomies over 1000 general anaesthesias and 1/60 failed intubations [8]. SPECIFIC CONSIDERATIONS OF THE OBSTETRIC AIRWAY Anaesthetic management of the obstetric patient has changed rapidly in the last 20 years, basically due to the development of neuraxial anesthetic blocks, with two main objectives: to reduce maternal mortality due to gastric content aspiration and failed intubation during general anesthesia, and to obtain better pain management during labor [9]. The Obstetric Anaesthetists Association (OAA) and the Difficult Airway Society (DAS) published the first specific guidelines for the management of the obstetric difficult airway in 2015 [10]. Airway management is profoundly affected by the anatomic and physiologic changes that develop during pregnancy, which are maximal in the third trimester and remain for 2-3 weeks after delivery. Anatomic changes include weight gain and enlargement of breasts, which can impair the use of the laryngoscope. The mucosa of the upper airway becomes edematous and has increased vascularization, and bleeds more easily. Swelling of the upper respiratory tract increases Mallampati score, not only along with the pregnancy, but also during labor and delivery [11]. Some other factors such as pre-eclampsia, fluid administration, oxytocin therapy, and Valsalva manoeuvres can increase swelling during labor and delivery. Nasal intubation is complicated in these patients by edema of the mucous membranes and bleeding risk. Among the physiologic changes of the respiratory system, the pregnant uterus causes a cephalad shift of the diaphragm, which decreases expiratory reserve

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volume. These changes make the pregnant woman more susceptible to hypoxaemia and hypercapnia with lesser apnoeic times. Compared to nonpregnant women, parturients present desaturation twice as fast [12]. Progesterone causes relaxation of the lower esophageal sphincter and delays gastric emptying. Gastrin secretion by the placenta increases gastric volumes and causes hyperchlorhydria. The upward shift of the stomach by the gravid uterus displaces the gastroesophageal junction and increases intra-abdominal and intragastric pressures. Obesity is nowadays a healthcare problem with increasing prevalence, which can complicate airway management in pregnant women. Obese patients have diminished thoracic compliance and oxygen reserves, as well as increased intraabdominal pressures. Obstructive sleep apnea and obesity impair facemask ventilation, and also, in case of failed intubation, the capacity of oxygenating the patient. Quinn et al found that, by every 1 Kg/m2 increase in BMI, the risk of difficult intubation increases by 7% [3]. Maternal age and higher body mass index are associated with a higher risk of preeclampsia, which is a specific risk factor for difficult airway due to increased edema and fragility of the oropharyngeal mucosa [13]. Besides these physiological and anatomical changes, there are local and human factors that contribute to the difficulty in the management of the airway in these women. Most important local factors are the isolation of the obstetric ward, frequently located far from the surgical ward, the lack of equipment for the management of the difficult airway and the lack of training and familiarity with the available equipment. These factors could be easily analysed by the simple act of endowing the obstetric unit with its own equipment for airway management. Human factors include communication organization, decision-making and behavior in a high-stress situation. One of the major contributing factors to disaster in airway management is lack of training. Effective training improves dexterity in airway management, but this requires teamwork as well as technical ability [14]. SAFE GENERAL ANAESTHESIA IN THE OBSTETRIC PATIENT Once the anatomical and physiological changes are known and the proper anaesthetic technic has been chosen, the problems related to the airway management can be anticipated and minimised. To achieve these goals, an adequate anaesthetic strategy preparation and planning is the best practice in order to make a successful laryngoscope and intubate such complex patients.

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Pre-operative Evaluation Any obstetric patient, who will undergo a surgical procedure, should have an airway assessment, not only to predict any potential intubation trouble but also to foresee problems regarding face mask ventilation or supraglottic device insertion, as well as to assess a surgical airway approach. This evaluation should be performed in the third trimester preferably [15]. Airway management complications can be reduced by previously identifying women at risk, with the purpose of planning a proper anaesthetic strategy [16]. Mallampati score, oral aperture, jaw subluxation, range of neck motion, thyromental distance and neck circumference are easy to evaluate bedside. A combination of more than one of these tests can increase positive predictive value, when comparing to the use of just one [17]. Brodsky reported that obesity will not predict difficult intubation, but wider neck circumference and higher Mallampati scores will [18]. Despite the importance of airway assessment seems evident, it is not routinely performed in usual clinical practice. Mckeen et al. observed that among 2633 general anaesthesia patients in an obstetric population over a period of 19 years, only 16,33% had a pre-operative evaluation [1]. Airway ultrasound is gaining popularity and can be used to identify the cricothyroid membrane, anticipating a more invasive approach [19]. Fasting and Antacid Prophylaxis Pregnant women are at higher risk of bronchoaspiration due to gastroesophageal reflux and delayed gastric emptying. The first can be demonstrated even if symptoms are lacking. Pain, labour and opioid treatment contribute to delay gastric emptying, which returns to normal status 18 hours after delivery [20]. All women who undergo a caesarean section are considered at risk of pulmonary aspiration, even in the case of a long fasting period. This aspiration may occur during intubation or extubation. Indeed, mortality is more likely during extubation rather than during anaesthesia induction [21]. Preparation for caesarean section includes a combination of H2 antagonists on surgery´s eve and two hours prior to surgery, with or without a prokinetic drug. Sodium citrate should be administered before induction. McDonell et al. reported high rates of antacid prophylaxis in elective cases, but just 64% in urgent caesarean section [22].

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In general terms, it can be affirmed that before a caesarean section usual fasting period should be considered: two hours for clear liquids and six hours for solid food [15]. In the UK, it is recommended that women during the second stage of labour should be stratified in low or high risk of undergoing general anaesthesia. The firsts are allowed to intake clear fluids, preferably as isotonic beverages, accompanied by H2 antagonists every 6 hours [23]. Planning and Preparation The success of the surgery depends on the team´s functionality, having help available if needed, and potentially necessary equipment. The World Health Organization suggests the application of a checklist before every surgical intervention [24]. The obstetrician should inform the anaesthesiologists of all clinical and surgical details in every case. A second anaesthesiologist should be available for consultation if required. The team must be familiar with the advanced airway trolley and this trolley must be checked regularly. Airway equipment must include different sized laryngeal masks, oropharyngeal cannulas, an alternative laryngoscope with various blades, supraglottic devices, videolaryngoscope and cricothyroidotomy material. Prior to induction, it is recommended to discuss potential airway problems and to plan airway management, including whether wakening up or not the patient if tracheal intubation failed. The final decision depends on the mother, foetus, medical team and clinical situation. A combination of all these factors makes each case unique. Main indications to proceed to general anaesthesia are maternal compromise that will not respond to resuscitation and foetal critical alterations of irreversible causes. Indications to wake up the patients include oedema and airway obstruction in the presence of a supraglottic device or face mask ventilation (Fig. 1). Patient Positioning Adequate positioning of the patient, in order to ease ventilation and intubation, is essential. Unfortunately, in emergent situations, mostly are mispositioned. Besides lateral displacement of uterus, it is recommended to elevate the head 20º30º. There is evidence in the literature that when the head is elevated, preoxygenation is more effective than in supine position [26]. This position increases functional residual capacity, enhances the view at laryngoscopy and reduces gastroesophageal reflux. The head up position improves ventilation mechanics and thus lengthens apnoea time.

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Fig. (1). Algorithm 1 – Safe obstetric general anaesthesia. Reproduced from Mushambi MC et al. Obstetric Anaesthetists' Association and Difficult Airway Society guidelines for the management of difficult and failed tracheal intubation in obstetrics. Anaesthesia 2015; 70(11): 1286 – 1306 (bit.ly/2P0dNo3) [10].

A proper position maximises intubation success, especially in obese obstetric patients. In these patients a ramped position favours laryngoscopic view when compared to sniffing position [27]. Preoxygenation During pregnancy, reduction in functional residual capacity and enlarged oxygen demands, results in shorter apnoea time and earlier desaturation. The aim of the preoxygenation is to provide a sufficient oxygen reserve to the patient, so that apnoea is tolerated without desaturation before the airway can be isolated. Apnoea time without desaturation is defined as the time interval occurring since the apnoea beginning until peripheral saturation reaches 90% or a lower value. This time is reduced in pregnant women when compared to non-pregnant women. Non-pregnant women, during apnoea, reach peripheral oxygen saturation below 90% after 1-2 minutes.

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After adequate preoxygenation, this time extends up to 7-10 minutes. In pregnant women, hypoxaemia occurs within the first minute, if a preoxygenation is lacking, and may be extended up 4 to 6 minutes if a proper preoxygenation has taken place. Preoxygenation is an effective manoeuvre to extend apnoea time. This manoeuvre is considered successful if an end-tidal O2 above 90% is achieved [28]. Many preoxygenation´s techniques have been described, including Tidal volume breathing, during 3 minutes or until ETO2>0,9 is achieved. Moreover, 4 to 8 deep breaths during 30 or 60 seconds respectively. Chiron et al. concluded that preoxygenation during 3 minutes is as effective as 8 deep breaths, the latter being more useful during emergent situations [29]. To achieve denitrogenation of these women a>=10L/min gas flow and an adequate face mask seal are required. High flow oxygen administration by the Opti-Flow system has been used to prevent hypoxia in non-pregnant patients during prolonged apnoea time. To date there are no surveys for pregnant patients, but some cases have been published, recognising that it might be useful to reduced desaturation in difficult airway cases [30]. Cricoid Pressure Sellick first described cricoid pressure in 1961 [31], and, since then, it has become routine during rapid sequence induction in patients at high risk of pulmonary aspiration. It must be applied correctly because failure in its application can result in serious complications such as hinder endotracheal intubation or supraglottic device insertion, impede face mask ventilation, pulmonary aspiration and rarely oesophageal rupture. Most of these problems occur due to excessive pressure. A 20 N pressure is probably enough and a 30 N force is more than enough to prevent regurgitation of gastric content. If patient is awake, a 20 N pressure causes retching and might trigger pulmonary aspiration and oesophageal rupture. Before anaesthetic induction, a 10 N (1 kg.) force is recommended, increasing until 30 N (3 kg.) when loss of consciousness occurs [32]. Successful endotracheal intubation must be confirmed by capnography. Cricoid pressure can be terminated as once as capnography has been checked and the endotracheal cuff inflated. Anaesthetic Induction Thiopentone has been the classic anaesthetic induction agent. However, its use is decreasing favouring propofol. The fact that anaesthesiologists are more familiar with propofol is increasing its popularity in these patients. Besides, this inductor agent inhibits airway reflexes more effectively than thiopentone. The NAP5 survey describes a higher incidence or intraoperative awareness when using

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inappropriately low doses ( 40

Obese 3 (previously “morbid obesity”)

ANATOMY CHANGES IN OBESITY There are multiple anatomy changes in obesity, which influence the airway [3]: ● ● ●

●

●

● ●

●

Increase in tongue size. Restricted mouth opening due to submental fat. Limited movement of the atlantoaxial joint and cervical spine due to the accumulation of fat at the thoracic and cervical levels. Diminution of the diameter of the upper airway by excessive submucosal tissue in the oral and pharyngeal cavity favoring the collapse of these structures. More frequent presence of high and anterior glottis than in the normal weight population. Degenerative joint disease. Increase in breast size (the mammary fat makes it difficult for the introduction of the laryngoscope and the insertion of supraglottic airway device). Increased neck and chest diameter (this morphology limits the urgent percutaneous approach of the larynx through cricothyroidotomy or tracheostomy).

Respiratory System The respiratory system of obese patients involves a reduction in functional residual capacity (FRC), important atelectasis and the shunt phenomenon in dependent pulmonary regions; however, resting metabolic rate, respiratory work and oxygen demand per minute are increased. This mixture of factors means that by interrupting respiration, arterial oxygen levels decrease rapidly [4]. It is undoubtedly said that BMI is inversely related to the impact of obesity on lung function, especially when the BMI exceeds 45. On the other hand, the pattern of distribution of excess fat (central vs peripheral) further conditions the restrictive pattern of pulmonary function based on BMI.

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Obesity leads to a series of respiratory modifications (Table 2) that affect volumes, compliance and ventilation/perfusion ratio, which in turn cause permanent hypoxemia due to the ineffectiveness of respiratory work. Table 2. Respiratory changes with obesity. Parameter

Obesity-Related Change

Work of breathing (WOB)

Increased

Functional residual capacity (FRC)

Decreased

Expiratory reserve volume (ERV)

Decreased

Total lung capacity (TLC)

Unchanged, though decreased in severe obesity

Vital capacity (VC)

Decreased

Forced expiratory volume in 1 s (FEV1)

Unchanged, though decreased in severe obesity

Forced vital capacity (FVC)

Unchanged, though decreased in severe obesity

FEV1/FVC

Unchanged, though decreased in severe obesity

Diffusing capacity of the lung for carbon monoxide (DLCO)

Unchanged in simple obesity

There is a decrease in the volume of the expiratory reserve (ERV) proportional to overweight, with maintenance or even an increase in residual volume, which causes a reduction in functional residual capacity (FRC) and an important risk of atelectasis formation. On the other hand, thoracic distensibility is reduced, with the consequent increase in the respiratory tract and the limitation of the individual to respond to the increase in ventilatory demand. Pulmonary compliance remains normal, except when obesity becomes long-standing, decreasing then due in part to the increase in blood in the lung parenchyma and partly to the fall of the CRF itself. In addition, changes in gas exchange occur for two reasons: there are areas of dead space (increased ventilation / perfusion ratio), originated by circulatory anomalies and hypoxic pulmonary vasoconstriction; and areas with shunt effect (decrease in the ventilation / perfusion ratio), due to the alveolar collapse produced by the decrease in FRC and the increase in pulmonary blood volume. While lung conditions allow it, a state of hyperventilation usually occurs to maintain normal CO2 levels, since the increase in the metabolism of the obese translates into an increase in the consumption of oxygen and an increase in the production of carbon dioxide.

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Sleep-Disordered Breathing Sleep-disordered breathing includes a series of diagnoses from obstructive sleep apnea (OSA) through obesity hypoventilation syndrome (OHS). The parapharyngeal structures are increased in size due to a deposit of adipose tissue, made with magnetic resonance imaging studies. In addition, it has been described that the increase in weight implies a reduction in the caliber of the airway (which translates into an increase in the resistance of this airway) [5]. It has been documented that these anatomical changes increase the risk of airway collapse. The retropalatal and/or the retroglossal regions are the points where the obstruction is most frequently observed. Between 40% and 90% of the obese population is affected by obstructive sleep apnea (OSA) and its main characteristic is a periodic decrease or interruption of breathing because during the sleep period a narrowing of the upper airways occurs [6]. In general, the incidence of postoperative desaturation, respiratory failure, postoperative cardiac events and ICU admission doubles even more than twice as patients presenting OSA. Moreover, difficult airway and laryngoscopy are described. OSA can become an obesity hypoventilation syndrome if it is not treated. This syndrome is characterized by the following triad: obesity (BMI > 35 kg/m2), sleep-disordered breathing (usually OSA) and daytime hypercapnia (pCO2 > 6 kPa). This subgroup of patients, conditioned by the combination of chronic hypoxemia and hypercapnia, may suffer acute and chronic hypoventilation and respiratory arrest in the early postoperative period because they are more susceptible to the effects of anesthetic agents and opioids. Difficult Airway Predictors and Tests It has been shown that there is a 30% higher risk of difficult/failed intubation in obese patients, although predictors for difficult laryngoscopy are the same as for non-obese patients [1]. Predictors of the difficult airway: 1. BMI: Some studies have shown that BMI is not an independent risk factor for difficult tracheal intubation in obese patients [7 - 9]. 2. Mallampati Classification: It has not by itself a high sensitivity and specificity

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3.

4.

5.

6.

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but is a part of the routine preoperative airway assessment [10]. Mallampati III or IV was the only independent risk factor for difficult intubation in obese patients [11]. Neck Circumference: We usually measure it at the level of the superior border of the cricoid cartilage. Large-neck circumference has been shown in several studies to be a predictor of difficult intubation in morbidly obese patients [7, 11]. Neck circumference > 40 cm has a 5% probability of problematic intubation and when greater than 60 cm is associated with a 35% probability of difficult laryngoscopy [7]. It has also been shown an association between large neck circumference was with male gender, higher Mallampati score, grade III laryngoscopy and OSA [7] (Fig. 1). Thyromental Distance (Patil’s Test): It is measured from the tip of the thyroid cartilage to the tip of the mandible with the neck fully extended. Problematic intubation is associated with a thyromental distance less than 6,5 cm and this predicts how much space do we probably have in the mouth to displace the tongue during laryngoscopy. A distance 35 kg/m2, preoxygenation with PEEP of 10 cm H2O during induction, increased the non-hypoxic apneic period by 50 percent (from 127 to 188 seconds) [16]. In other trials, application on NIV with PEEP prior to induction resulted in higher end tidal oxygen [17] and post intubation PaO2 [18] tan spontaneous breathing of 100 percent oxygen. In addition to these techniques, the administration of high-flow nasal oxygen during preoxygenation and continued during apnea can prolong the time to desaturation during intubation [19]. Patient Positioning At the moment of induction of anesthesia, the patient should be placed in a ramped position. The bed can be tilted (Fig. 2) (or a stack of blankets or preformed ramp can be used). The tragus of the ear must be at the level of the sternum. This position optimizes the alignment of the oral, pharyngeal and laryngeal axes, improving the conditions for intubation, as well as improves lung mechanics, oxygenation and ventilation [20]. The goal is to achieve an adequate anaesthetic depth and relaxation to facilitate bag-mask ventilation and laryngoscopy. Minimizing the time from induction to intubation will reduce the risk of oxygen desaturation. Between the different drugs used in anaesthesia, those with fast onset and offset, should be chosen for obese patients. A very careful drug dosing titration is necessary. Succinylcholine has been used to facilitate rapid sequence intubation (RSI) since the presence of Sugammadex, Rocuronium has become an effective

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and safe choice for difficult airway management. Fasciculations associated to Succinylcholine are associated with an increase of oxygen consumption and a shortening of safe apnea time. A dose of 1,2 mg/kg of Rocuronium of ideal body weight provides excellent intubation conditions. In case of emergency, the reversing dose of Sugammadex must be calculated and available for preparation beforehand [21].

Fig. (2). Bed with the pre-formed ramp in the operating room.

Awake tracheal intubation should be considered in patients with known or anticipated difficult airways (Fig. 3).

Fig. (3). Awake Fiberoptic intubation.

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Tracheal Tubes Once an obese patient is anesthetized, tracheal intubation and controlled ventilation is the airway management procedure of choice. As tracheal diameter reduces slightly with increasing body weight, the size of the tracheal tube and the tidal volume during controlled ventilation, should be chosen by the ideal body weight [21] In case of difficulty or failure of intubation, it must be immediately managed in accordance with the Difficult Airway Society guidelines [22]. Introducers When a suboptimal laryngeal inlet view is obtained with direct or indirect laryngoscopy, the use of a tracheal tube introducer (EschmannTM or FrovaTM) or a malleable stylet could be helpful [5]. Supraglottic Airway Devices In highly selected patients, scheduled for short procedures where the patient could be kept head-up, supraglottic airway devices (SAD) may be considered the primary airway device [21]. Double-lumen SAD with gastric channels could be used to ventilate morbidly obese patients as a bridge before tracheal intubation. SAD is have been shown to be easier to use and provides a superior ventilation score when compared with face-mask ventilation in novice hands [23, 24]. In morbidly obese patients, second-generation SAD offers greater leak pressures, so they may be safer, even though they do not preclude an airway aspiration. SAD could be used as a stent to preserve the airway open and to ease the access to the laryngeal inlet when there is a stained or bloody field. With this purpose, a tracheal tube could be railroaded over a bronchoscope through the SAD and thus be guided through the glottis. Another technique is the use of an Aintree Intubating Catheter, that could be advanced over the bronchoscope into the trachea through the SGA. Videolaryngoscopes Videolaryngoscopy (VL) provides a better glottic view than direct laryngoscopy, while producing less airway trauma and fewer desaturation when compared with direct laryngoscopy (DL) in the obese population [25]. Nevertheless, the intubation time was not equally reduced with all the VL [26].

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An improved laryngeal view does not always result in easy intubation, and it may be necessary to use an introducer. Despite the huge and increasing number of VL available, not a single one has demonstrated to be superior to intubate obese patients. However, as VL could be helpful in the airway management of these patients, they should be quickly available in the operating room (Fig. 4).

Fig. (4). Intubation of obese patients using Airtraq with a similar movement as a guedel as it is introduced.

Surgical Airway In a “cannot intubate, cannot ventilate” scenario, emergency cricothyroidotomy could be especially challenging in obese patients because of undefined anatomical landmarks. The use of ultrasonography may help to identify the cricothyroid membrane precisely in patients with large neck circumference and impalpable landmarks [27]. Extubation and Postoperative Oxygenation Tracheal extubation is a critical step during the emergence of general anesthesia. As shown in the Fourth National Audit Project (NAP4) of the Royal College of Anesthetists and the DAS, in 1/3 of the reported cases relating to anesthesia, major airway complications occurred during emergence [28]. Obesity is an independent airway risk factor of difficult extubation and extubation problems are more frequent in obese patients and patients with OSA. These patients are more sensitive to residual effects of opioids anesthesia, which may

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cause a reduction in pharyngeal tone and increase the risk of aspiration and airway obstruction. Moreover, a strong inspiratory effort could cause a significant negative intrathoracic pressure, which opens the esophagus, increasing the risk of regurgitation. Additionally, a residual neuromuscular blockade can increase the frequency of postoperative complications, so neuromuscular block should be totally reversed. The frequency of postoperative airway complications is shown to be reduced with the utilization of a peripheral nerve stimulator to assure a TOF ratio of 0.9 or above. The main objective is to provide continuous oxygen delivery to the patient, without airway stimulation. It is important to have a back-up plan to assure ventilation and reintubation if extubation fails. It is also important to achieve cardiovascular stability, adequate fluid balance and satisfactory analgesia. The purpose of pre-oxygenation before extubation is to maximize pulmonary oxygen stores by raising the FEO2 above 0.9, or as close to the FIO2 as possible. There is a growing tendency in relation to extubate the patient in a head-up (reverse Trendelenburg) or semi-recumbent position. This is particularly beneficial in the obese population as it gives a mechanical advantage to respiration and provides better conditions to manage the airway. Usually it is safer to perform awake extubation. The risk of airway obstruction may be reduced by exchanging the tracheal tube for a SAD before emergence. This procedure is superior to either awake or deep extubation and may be beneficial in cases where there is a risk of rupture of the surgical repair due to the cardiovascular stimulation consequence of the tracheal tube. It could also be useful in smokers, asthmatics and patients with irritable airways. It is not suitable for patients with difficult intubation or at risk of regurgitation. Extubation could also be performed using an airway exchange catheter. It may be used as a guide over which a tracheal tube can be passed and also permit to oxygenate the patient’s lungs. During the transfer to the recovery room, oxygen should be provided. Portable monitoring may be taken into consideration if there is a great distance or in the presence of the patient’s instability. In the recovery room, there should be capnography available. Deep breaths and coughing to clear secretions should be encouraged. It may be observed that in

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patients with OSA, a nasopharyngeal airway may cause upper airway obstruction. If the patient is a CPAP device user, it should be available for use in the recovery room. CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that the content of this chapter has no conflict of interest. ACKNOWLEDGEMENTS Declared none. REFERENCES [1]

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position than in the supine position in severely obese patients: a randomized controlled study. Anesthesiology 2005; 102(6): 1110-5. [http://dx.doi.org/10.1097/00000542-200506000-00009] [PMID: 15915022] [13]

Baraka AS, Taha SK, Aouad MT, El-Khatib MF, Kawkabani NI. Preoxygenation: comparison of maximal breathing and tidal volume breathing techniques. Anesthesiology 1999; 91(3): 612-6. [http://dx.doi.org/10.1097/00000542-199909000-00009] [PMID: 10485768]

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Gagnon C, Fortier LP, Donati F. When a leak is unavoidable, preoxygenation is equally ineffective with vital capacity or tidal volume breathing. Can J Anaesth 2006; 53(1): 86-91. [http://dx.doi.org/10.1007/BF03021532] [PMID: 16371614]

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Carron M, Zarantonello F, Tellaroli P, Ori C. Perioperative noninvasive ventilation in obese patients: a qualitative review and meta-analysis. Surg Obes Relat Dis 2016; 12(3): 681-91. [http://dx.doi.org/10.1016/j.soard.2015.12.013] [PMID: 26948450]

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Gander S, Frascarolo P, Suter M, Spahn DR, Magnusson L. Positive end-expiratory pressure during induction of general anesthesia increases duration of nonhypoxic apnea in morbidly obese patients. Anesth Analg 2005; 100(2): 580-4. [http://dx.doi.org/10.1213/01.ANE.0000143339.40385.1B] [PMID: 15673897]

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Delay JM, Sebbane M, Jung B, et al. The effectiveness of noninvasive positive pressure ventilation to enhance preoxygenation in morbidly obese patients: a randomized controlled study. Anesth Analg 2008; 107(5): 1707-13. [http://dx.doi.org/10.1213/ane.0b013e318183909b] [PMID: 18931236]

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Futier E, Constantin JM, Pelosi P, et al. Noninvasive ventilation and alveolar recruitment maneuver improve respiratory function during and after intubation of morbidly obese patients: a randomized controlled study. Anesthesiology 2011; 114(6): 1354-63. [http://dx.doi.org/10.1097/ALN.0b013e31821811ba] [PMID: 21478734]

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Ramachandran SK, Cosnowski A, Shanks A, Turner CR. Apneic oxygenation during prolonged laryngoscopy in obese patients: a randomized, controlled trial of nasal oxygen administration. J Clin Anesth 2010; 22(3): 164-8. [http://dx.doi.org/10.1016/j.jclinane.2009.05.006] [PMID: 20400000]

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Collins JS, Lemmens HJ, Brodsky JB, Brock-Utne JG, Levitan RM. Laryngoscopy and morbid obesity: a comparison of the “sniff” and “ramped” positions. Obes Surg 2004; 14(9): 1171-5.

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Nightingale CE, Margarson MP, Shearer E, et al. Peri-operative management of the obese surgical patient 2015: Association of Anaesthetists of Great Britain and Ireland Society for Obesity and Bariatric Anaesthesia. Anaesthesia 2015; 70(7): 859-76. [http://dx.doi.org/10.1111/anae.13101] [PMID: 25950621]

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Frerk C, Mitchell VS, McNarry AF, et al. Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults. Br J Anaesth 2015; 115(6): 827-48. [http://dx.doi.org/10.1093/bja/aev371] [PMID: 26556848]

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Keller C, Brimacombe J, Kleinsasser A, Brimacombe L. The Laryngeal Mask Airway ProSeal(TM) as a temporary ventilatory device in grossly and morbidly obese patients before laryngoscope-guided tracheal intubation. Anesth Analg 2002; 94(3): 737-40. [http://dx.doi.org/10.1097/00000539-200203000-00048] [PMID: 11867408]

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Abdi W, Dhonneur G, Amathieu R, et al. LMA supreme versus facemask ventilation performed by novices: a comparative study in morbidly obese patients showing difficult ventilation predictors. Obes Surg 2009; 19(12): 1624-30. [http://dx.doi.org/10.1007/s11695-009-9953-0] [PMID: 19730959]

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Ndoko SK, Amathieu R, Tual L, et al. Tracheal intubation of morbidly obese patients: a randomized trial comparing performance of Macintosh and Airtraq laryngoscopes. Br J Anaesth 2008; 100(2): 263-8. [http://dx.doi.org/10.1093/bja/aem346] [PMID: 18211999]

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Yumul R, Elvir-Lazo OL, White PF, et al. Comparison of three video laryngoscopy devices to direct laryngoscopy for intubating obese patients: a randomized controlled trial. J Clin Anesth 2016; 31: 717.

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CHAPTER 14

An Update on Airway Management in the Intensive Care Unit Paula Martínez Fariñas1,*, Ignacio Portalo González2, Clara Morandeira Rivas3, Barbara Algar Yañez4 and Enrique Platas Gil5 Department of Anesthesiology and Critical Care Medicine, Hospital FREMAP Majadahonda, Madrid, Spain 2 Department of Anesthesiology and Critical Care Medicine, Hospital Infanta Cristina, Parla, Madrid, Spain 3 Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Fundación Alcorcón, Madrid, Spain 4 Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Infanta Leonor, Madrid, Spain 5 Servicio de Medicina Intensiva, Hospital Universitario de la Princesa, Madrid, Spain 1

Abstract: Tracheal intubation is a frequent and dangerous procedure in the intensive care units (ICU), and is usually performed in more difficult conditions than in the operating room. Intubation failure can occur unexpectedly, and is the second most common event reflected in the ICU in the NAP4. Complications that cause damage to the patient (severe hypoxemia, arrhythmia, hypotension, cardiovascular collapse, etc.). Videolaryngoscopes present theoretical benefits, as proper and correct use, offering the potential to reduce the difficulty of intubation in the ICU. Videolaryngoscopes allow a view of the entrance of glottis independent of the line of sight, and have also been shown to improve glottis and intubation success rates, specifically in patients with known predictors of the difficult airway (DA).

Keywords: Airway management, Complications, Critical patient, Difficult airway, ICU, Intensive care, Laryngoscopy, NAP4, Tracheal intubation, Videolaryngoscopes. INTRODUCTION Airway management, optimize oxygenation and tracheal intubation are common procedures in the intensive care units (ICU). The performing conditions are more complicated and the harm we can cause to patients is higher than those exhibit Corresponding author Paula Martínez Fariñas: Department of Anesthesiology. Hospital FREMAP Majadahonda, Madrid, Spain; Tel/fax number 0034 916 26 56 80; E-mail: paula_martinez-fariñ[email protected] *

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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during anaesthesia or in the emergency department, so intubation in the ICU is frequently required in emergency situations becoming a high-risk procedure. The 4th National Audit Project (NAP4) of the Royal College of Anaesthetists and Difficult Airway Society (DAS) [1] found a higher rate of adverse outcomes and deficiencies of airway management in ICU [2]. At least one in four major airway events reported to NAP4 was from ICU or the emergency department. Indeed, the failure of airway management was the second most common event [3] and some factors that contribute to these difficulties are [4, 5]: ●

Patient Factors: Comorbidities and lack of physiological reserve. Organ dysfunction: respiratory, cardiovascular, neurological, renal and hepatic. Inefficient preoxygenation secondary to ventilation/perfusion mismatch, low oxygenation reserve leading to rapid low oxygen saturation levels during the manipulation. Potentially full stomach due to gastroparesis and a high risk of aspiration frequently is an emergent procedure. Are more likely to have a poorer Cormack-Lehane grade view at the laryngoscopy. Vulnerable airways: secondary to surgery, trauma (cervical, head and neck.), oedema. Environmental Factors: (consider as a hostile environment): Lack of space due to the equipment (infusion pumps, ventilator, monitors, haemofilter, ECMO.). The ICU bed design does not facilitate optimized positioning. Poor access to the airway due to cervical collar, mattresses, paediatric frames. Poor lightening. Staff and Training Factors: Senior doctors with airway skills are not always available. ICU nurses usually have less airway skills and experience in assisting intubation. Supervising the intubation improves success [6]. Equipment Factors: Capnography available to ensure the tracheal intubation. “Airway trolley” with standardized airway equipment and bronchoscope in every ICU [1]. Cognitive aids: guidelines/protocols. Check list [2] (Fig. 1). ❍ ❍

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Fig. (1). Intubation Check list: critically ill adults (bit.ly/2w60740).

MANAGEMENT The incidence of difficult intubation in ICU is increased and varies from 8-23% depending on the series [10]. Anticipating problems and preventing them with careful preparation can reduce the incidence of life-threatening complications such as respiratory and cardiovascular. Distinguish Risk of Difficult Intubation Identifying patients with difficult airway is highly recommended and it helps to airway management planning. However, this assessment has a low positive predictive value and specificity [2]. The MACOCHA score is the only validated airway tool in critically ill patients [7 - 9], which is coded from 0-12. In critically ill patient the difficult airway is predicted when score ≥ 3 (Table 1). Patient´s Preparation Most of the ICU tracheal intubations occur as an emergency procedure, but if possible, it is highly recommended to follow a checklist and plan some strategy. ●

●

●

Standard monitorization: oximetry, blood pressure, heart rate, ECG, capnography. Prepare the basic material: the adequate size of the oropharyngeal cannula and facial mask, the intubation trolley, the vacuum cleaner. Position [10]: Whenever it is possible, the patient´s head should be up to 25-30

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degrees or semi-seated because they can achieve better PaO2 [11]. The “sniffing position” with the lower cervical spine is flexed and the upper cervical spine is extended to line up the airway axis. However, if there is a spine injury, it is not possible to move the neck, so it is recommended to tilt the whole bed head-up. Table 1. MACOCHA score. Factors

Score

M. Mallampati score III or IV

5

A. Apnoea syndrome (obstructive)

2

C. Cervical spine limitation

1

O. Opening mouth < 3 cm.

1

C. Coma

1

H. Hypoxaemia

1

A. Anaesthesiologist untrained or non-anaesthesiologists

1

Preoxygenation The preoxygenation goal is to denitrogenate the alveolus replacing it with oxygen. This manoeuvre increases the O2 reserve and allows longer apnoea without desaturation. As the main cause of intubation in the ICU is the acute hypoxemic insufficiency, desaturation is a common complication during tracheal intubation in ICU [3], so that is why an optimum preoxygenation is mandatory. The end-tidal oxygen concentration (>85%) is the best way to measure a proper preoxygenation, although it is not always available in the ICU. Usually, in critically ill patients, the standard preoxygenation technique (100% FiO2 and 10-15 lpm fresh gas flow during 3min with a tight facemask or 3-8 vital capacities) is poorly effective [12]. Non-invasive mechanical ventilation is the preferred technique preoxygenation in ICU [13, 14]. Anaesthetists have different options: ●

● ●

for

FiO2 100%, with PEEP of 5-10 cmH2O and a CPAP of 5-15 cmH2O. The CPAP improves oxygenation, extends the safe apnoea time and reduces the absorption atelectasis associated with FiO2 100% breathing, but is recommended not to exceed pressures > 20 cm H2O causing gastric distension. Nasal oxygenation with a standard mask. High-flow nasal oxygenation can provide 100% FiO2 warm and humidified with 30-70 lpm [13]. It is contraindicated in severe facial trauma and suspected fractures of the base of the skull.

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The preoxygenation is the O2 administration during the onset of neuromuscular blockade while the patient is in apnoea. Using standard nasal or buccal cannula only increases oxygen concentration in the hypopharynx. The DAS recommends facemask ventilation with CPAP before attempting intubation, especially if hypercarbia is problematic, and between intubation attempts [2]. Facemask ventilation may be improved by “two-person technique”, airway adjuncts or both. Anaesthesia Induction As critically ill patients have a high risk of aspiration, rapid sequence induction is preferred. There is not a perfect induction agent in the ICU, which meets all the safety criteria and ideal characteristics. More studies are required to determine which drug is the best [15]. The chosen drug depends on the clinical situation of the patient. The drug administration sequence usually is an opioid, a hypnotic agent, and a neuromuscular blocking agent (NMBA): ●

●

Opioids: It is preferred rapidly acting opioids. An important advantage is that it reduces the dose of the hypnotic agent. Hypnotic Agent: Etomidate: The major concern is the increased risk of adrenal insufficiency in continuous or prolonged infusion. Use with caution in septic patients [16]. Ketamine: Can be a good alternative. Ketamine stimulates the sympathetic system, which can lead to great advantage in patients haemodynamically unstable. Propofol: It is used worldwide. The main problem is the vasodilatation and hypotension [17]. Although structurally, it is different, clinical actions and effects on cerebral activity and intracranial dynamics are very similar to short-acting barbiturates (e.g., Thiopental) [18]. Thiopental: Barbiturates have a dose-dependent sedative, hypnotic and anesthetic action, furthermore anticonvulsant and cerebro-protective properties. They produce central nervous system depression by facilitation of chloride conductance at inhibitory GABA ion channels [18]. NMBA [19]: These agents have improved facemask ventilation, intubating conditions, avoiding laryngospasm, easy insertion of supraglottic devices [15]. The rapid onset NMBA is fast enough to allow rapid sequence intubation Succinylcholine: It has many side effects (life-threatening hyperkalaemia, bradycardia, arrhythmias, anaphylaxis, etc) and in addition, many ❍

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contraindications are common in ICU: neuromuscular junction damage, extensive burns, rhabdomyolysis, prolonged bed rest). Rocuronium: With doses of 0.9 mg/kg the intubation conditions are similar to succinylcholine [20]. Another advantage is that the use of sugammadex ensures fast recovery from rocuronium.

Another part of the rapid sequence induction (RSI) is the cricoid pressure (Sellick manoeuvre). It should start with awake patients and 10 N of pressure and after the anaesthesia induction, the pressure must be increased to 30 N [3]. The aim of this technique is to occlude the oesophagus preventing the aspiration, but sometimes it only achieves to complicate the intubation. If this occurs, it is preferable to reduce or release the pressure and allow the intubation or the facemask ventilation [2]. As well it is important to consider the prevention of the complications during tracheal intubation. Anaesthetists can consider two types of complications [21, 22]: ●

●

Severe life-threatening complications: cardiac arrest or death, cardiovascular shock (define as SBP < 65 mmHg or vasoactive drugs needed), right ventricular failure, hypoxaemia (SpO2 < 80%), metabolic acidosis. Moderate complications: arrhythmias with the pulse, oesophageal or bronchial intubation, aspiration, dental injury, difficult intubation.

Recruitment Manoeuvres Anaesthesia and intubation attempts worsen the gas exchange and facilitate the atelectasis. In many patients, these are added to the hypoxic situation due to their respiratory failure. For that reason, recruitment manoeuvres are frequently needed. They consist of a progressive increase in the inspiratory pressure, for example, CPAP of 30-40 mmHg during 25-30 seg. immediately after the intubation. They are associated with a higher PaO2 secondary to the increase of lung volume and the decrease of the atelectasis. Intubation in the ICU Patient After the preparation, oxygenation, induction and mask ventilation comes the tracheal intubation. The ideal airway management is a coordinated sequence of logical plans that covers the backups when it is needed. Direct Laryngoscopy The Macintosh laryngoscope remains the most popular device for the first attempt [9]. Multiple intubation attempts are associated with airway trauma and

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deterioration, progressing to a “cannot intubate, cannot oxygenate” situation. That is why the number of intubation attempts is limited to three [2]. After the first intubation failure, anaesthetist need to ask for help and improve the laryngoscopic view. Firstly, it will be necessary to check the correct patient position and muscle relaxation. When it is done, we can change the blade, optimize the external manipulation with BURP (backwards, upwards, rightwards pressure) or releasing the cricoid pressure, use other devices such as stylets, bougies or videolaryngoscopes or change the operator. The endotracheal tube commonly used in the ICU is high volume - low pressure cuffs with subglottic suction. They are associated with less incidence of trauma and tracheal stenosis [5]. In cases of difficult airway management, usually, a small tube is preferred to easier the intubation, and after the crisis is solved, it could be exchanged easily. It is mandatory to check the tracheal intubation by obtaining a waveform in the capnography [2]. Some reasons for the lack of capnography trace are: tube misplacement, tube obstruction (severe oedema, blood, secretions, bronchospasm.), water in the circuit, etc. Videolaryngoscopy Nowadays, the videolaryngoscopes are becoming more popular, not only in the operation room but also in the ICU or emergency department [23]. It can be used either initially when the difficult airway is suspected or after the failure of direct laryngoscopy. There are three types of videolaryngoscopes (VL): ●

●

●

VL with “Standard” rigid blade (C-MAC, McGrath MAC, Medan, etc.). They are similar to the Macintosh laryngoscope, so it reduces the learning curve theoretically. VL with Angled Rigid Blade (Glidescope, King Vision, etc.). They facilitate the glottic view, but sometimes direct the endotracheal tube is more difficult. Videolaryngoscopes with channel to guide the ETT (Airtraq, King vision, etc.). The channelled blade allows the endotracheal tube introduction, so the modifications are done with the VL instead of the tube (Fig. 2).

Some of the VL disadvantages are: ● ● ●

They use batteries or they need to be plugged in. Low quality of image with secretions, blood or fog. It requires a learning curve.

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There is an important lack of evidence comparing direct laryngoscopy and videolaryngoscopy in the ICU, especially performed by non-anaesthesiologists. The MACMAN trial [24] (McGrath MAC Videolaryngoscope [VL] Versus Macintosh Laryngoscope [ML] for orotracheal intubation in the critical care unit) was the first randomised multicentre study of videolaryngoscopy for endotracheal intubation in ICU. They found no differences in first-pass success between the VL and the ML, even adjusting for MACOCHA score and operator expertise. Moreover, they concluded that the reason for intubation failure in the ML group was the inability to see glottis and was the failure of tracheal catheterization.

Fig. (2). Airtraq. Images courtesy of Prodol (airtraq.com).

Videolaryngoscopy has demonstrated to be useful in first attempt success in the operating room, especially in the difficult airway [25 - 28], but these results are not necessarily transferrable to the ICU conditions (Fig. 3). However, a VL should be available and considered as an option for intubation in critically ill patients.

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Fig. (3). Intubation with Airtraq. A. Technique to guide Endotracheal Tube (ET) B. Technique for orienting the ET. Images courtesy of Prodol (airtraq.com).

Supraglottic Airway Devices (SAD) SADs are commonly used as plan B when intubation in ICU has failed, that happens in 10-30% of critically ill patients [29]. The aim is to restore the oxygenation, either with facemask or second-generation SAD. After three intubation attempts, “fail intubation” is declared, so an airway rescue

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is needed. The Vortex approach suggests SAD placement interspersed with facemask ventilation [30] (Fig. 4):

Fig. (4). Vortex approach (vortexapproach.org/) [30].

● ●

●

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Green zone represents the effective oxygenation and a relative safety situation. In the Vortex intubation attempts, SAD placement and facemask ventilation form an alternating continuum. However, in critically patients, the intubation attempts come first, and afterwards, if they fail, they rescue the airway management with the SAD placement and the facemask ventilation. When the three techniques fail, then there is a spiralling to the Vortex, where anaesthetists found the front of the neck access (FONA). During the oxygenation rescue attempts, an expert may arrive. It is permitted an extra attempt is performed by an expert in each phase: intubation, SAD insertion and facemask ventilation. The optimal ventilation must be checked by capnography waveform, or if it is not available, with the oxygenation improvement.

After failed intubation is declared, three facemask ventilation attempts are permitted with changes of size, type, adjuncts, position and operator as required. The SADs have some advantages in comparison with the facemask ventilation.

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SADs provide some protection from aspiration, facilitate intubation using other devices and more frequently enable oxygenation. The second generation of SAD is the most popular because they have more properties of a desirable device [31]. For example, they reduce the risk of aspiration due to a higher oropharyngeal seal pressure and oesophageal drain tube; they more likely to accomplish the reoxygenation, ventilation and maintain the PEEP; some of these SADs also have a narrow channel that let fibreoptic intubation through it. At the end, the SAD used depends on the availability and experience of the operator. Fibreoptic Bronchoscope Intubation In ICU, the fibreoptic intubation is usually performed through the SAD. Many projects, as NAP4 audit, or scientific societies, such as DAS, recommend immediate availability of fibreoptic endoscopes in the ICU, chiefly the single-use, disposable ones. Some limitations are: ●

● ●

The small endotracheal tube size. Usually has to be a 6 mm inner diameter or smaller to pass through the channel. The fibreoptic intubation image can be lost due to blood discharge. The training curve is more difficult and is essential.

A single attempt of intubation through SAD is recommended to avoid airway trauma and worsening the situation to a “cannot Intubate, Cannot Oxygenate (CICO)” situation. Front of the Neck Access (FONA) [32] This is an emergency situation indicated after a failed intubation and a failed ventilation either with SAD or facemask. Critically ill patients, due to their fragile conditions, need a quick transition to FONA because if not, deep hypoxemia and cardiac arrest are inevitable. An important worldwide problem is the delay of the progression to FONA resulting in an avoidable harm1. In order to prevent this delay, the sequence should be: getting the FONA set after the first failed intubation attempt; open the set after a failed attempt of SAD or facemask ventilation and use the set when a CICO situation is declared.

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Current evidence supports a scalpel cricothyroidotomy as a fast and reliable technique, recommended by the DAS. The keys steps are: ● ●

●

Maximum neck extension. Locate the cricothyroid membrane and make an incision (horizontal if the membrane is easily palpable or vertical incision if not). Insert a bougie as a guide for a 5-6 mm tracheal tube.

The transtracheal jet ventilation or high-pressure ventilation via a narrow cannula was a common practice during the FONA. NAP4 identified high rates of device and technique failure and complications. In critically ill patients, jet ventilation is poorly effective because their recruitment and preoxygenation need PEEP and is difficult to get without a cuffed tube. Some complications of the jet ventilation are [33]: barotrauma, subcutaneous emphysema hindering later approaches, etc. CHECKLIST AND PREOXYGENATION -

Head up if possible. Assess airway and identify cricothyroid membrane. Capnograph available. Preoxygenation: Facemask, CPAP, HFNO… Optimise cardiovascular system. Share a plan for failure.

MACOCHA < 3

MACOCHA < 3

Two operators if possible

Two operators mandatory

Metal blade if possible

Metal blade mandatory

Malleable stylet up to physician

Malleable stylet recommended

RSI mandatory

RSI mandatory Fig. (5) cont.....

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Fig. (5). Airway Management Algorithm in The ICU Patients [2, 7].

Other surgical approaches have insufficient evidence to recommend them for FONA, such as Seldinger cricothyroidotomy, percutaneous and surgical tracheostomy, etc. Afterwards, a capnography trace is also needed to ensure ventilation. Once the emergency situation is solved, fibreoptic inspection or X-ray is also recommended to check the optimal tube placement until it is converted to a tracheal tube or tracheostomy. CONCLUSION ●

Airway management in the intensive care unit (ICU) differs significantly from routine surgical procedures in the operating room, and uses to be a challenging procedure and is frequently associated with life- threatening complications.

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The use of a protocol and algorithms for airway management that includes appropriate staffing, pre-oxygenation, adequate ventilation, pulmonary gas exchange and strategies to avoid cardiovascular complications, has been shown to decrease complications. Many physicians are working in ICUs and have no anaesthesiological experienced. Critical care physicians must be familiar with the equipment and techniques to maintain and secure the airway, because the high practical skill of airway management is needed in critically ill patients.

CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that the content of this chapter has no conflict of interest. ACKNOWLEDGEMENTS Declare none. REFERENCES [1]

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Dixon BJ, Carden JR, Burn AJ, et al. Preoxygenation is more effective in the 25 degrees head-up position tan in the supine position in severely obese patients: A randomized controlled study. Anesthesiology 2005; 102(6): 1110-5. http://www.ncbi.nlm.nih.gov/pubmed/15915022 discussion 5ª.

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Jaber S, Monnin M, Girard M, et al. Apnoeic oxygenation via high-flow nasal cannula oxygen combined with non-invasive ventilation preoxygenation for intubation in hypoxemic patients in the intensive care unit: the single-centre, blinded, randomised controlled OPTINIV trial. Intensive Care Med 2016; 42: 1877-87.

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Mosier JM, Hypes CD, Sakles JC. Understanding preoxygenation and apneic oxygenation during intubation in the critically ill. Intensive Care Med 2017; 43(2): 226-8. [http://dx.doi.org/10.1007/s00134-016-4426-0] [PMID: 27342820]

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Jabre P, Combes X, Lapostolle F, et al. Etomidate versus ketamine for rapid sequence intubation in acutely ill patients: a multicentre randomised controlled trial. Lancet 2009; 374(9686): 293-300. [http://dx.doi.org/10.1016/S0140-6736(09)60949-1] [PMID: 19573904]

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Koenig SJ, Lakticova V, Narasimhan M, Doelken P, Mayo PH. Safety of propofol as an induction agent for urgent endotracheal intubation in the medical intensive care unit. J Intensive Care Med 2015; 30(8): 499-504. [http://dx.doi.org/10.1177/0885066614523100] [PMID: 24536033]

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Paul BS, Paul G. Sedation in neurological intensive care unit. Ann Indian Acad Neurol 2013; 16(2): 194-202. [http://dx.doi.org/10.4103/0972-2327.112465] [PMID: 23956563]

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Marsch SC, Steiner L, Bucher E, et al. Succinylcholine versus rocuronium for rapid sequence intubation in intensive care: a prospective, randomized controlled trial. Crit Care 2011; 15(4): R199. [http://dx.doi.org/10.1186/cc10367] [PMID: 21846380]

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Tran DTT, Newton EK, Mount VA, Lee JS, Wells GA, Perry JJ. Rocuronium versus succinylcholine for rapid sequence induction intubation. Cochrane Database Syst Rev 2015; 10(10): CD002788. [http://dx.doi.org/10.1002/14651858.CD002788.pub3] [PMID: 26512948]

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Jaber S, Amraoui J, Lefrant JY, et al. Clinical practice and risk factors for immediate complications of endotracheal intubation in the intensive care unit: a prospective, multiple-center study. Crit Care Med 2006; 34(9): 2355-61. [http://dx.doi.org/10.1097/01.CCM.0000233879.58720.87] [PMID: 16850003]

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De Jong A, Molinari N, Conseil M, et al. Video laryngoscopy versus direct laryngoscopy for orotracheal intubation in the intensive care unit: a systematic review and meta-analysis. Intensive Care Med 2014; 40(5): 629-39. [http://dx.doi.org/10.1007/s00134-014-3236-5] [PMID: 24556912]

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Lascarrou JB, Boisrame-Helms J, Bailly A, et al. Video laryngoscopy vs direct laryngoscopy on successful first-pass orotracheal intubation among ICU patients a randomized clinical trial. JAMA 2017; 317(5): 483-93. [http://dx.doi.org/10.1001/jama.2016.20603] [PMID: 28118659]

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Taylor AM, Peck M, Launcelott S, et al. The McGrath Series 5 videolaryngoscope vs the Macintosh laryngoscope: A randomised, controlled trial in patients with a simulated di cult airway. Anaesthesia 2013; 68(2): 142-7. Available from: www.ncbi.nlm.nih.gov/pubmed/2312147010.1111/anae.12075

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Malik MA, Subramaniam R, Maharaj CH, Harte BH. Randomized controlled trial of the Pentax AWS®, Glidescope®, and Macintosh laryngoscopes in predicted GLIILFXOW intubation. British J Anaesth. 2009 [cited 2017 Aug 8];103(5): 761-8.

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Wallace CD, Foulds LT, McLeod GA, Younger RA, McGuire BE. A comparison of the ease of tracheal intuba- tion using a McGrath MAC laryngoscope and a standard Macintosh laryngoscope. Anaesthesia 2015; 70: 1281-5.

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Lewis SR, Butler AR, Parker J, Cook TM, Smith AF. Videolaryngoscopy versus direct laryngoscopy for adult patients requiring tracheal intubation. Cochrane Database Syst Rev 2016; 11CD011136 [http://dx.doi.org/10.1002/14651858.CD011136.pub2] [PMID: 27844477]

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Futier E, Constantin J-M, Petit A, et al. Positive end-expiratory pressure improves end-expiratory lung volume but not oxygenation after induction of anaesthesia. Europ J of Anaesth 2010; 27(6): 508-13. [http://dx.doi.org/10.1097/EJA.0b013e3283398806]

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Chrimes N. The Vortex: a universal ‘high-acuity implementation tool’ for emergency airway management. Br J Anaesth 2016; 117: i20-7.

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Kristensen MS, Teoh WH, Asai T. Which supraglottic airway will serve my patient best? Anaesthesia 2014; 69: 1189-92. [http://dx.doi.org/10.1111/anae.12856]

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Pracy JP, Brennan L, Cook TM, et al. Surgical intervention during a can’t intubate can’t oxygenate (CICO) event: emergency front-of-neck airway (FONA)? Br J Anaesth 2016; 117: 426-8.

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CHAPTER 15

An Update on Airway Management in the Emergency Department Alicia Guarnizo Ruiz1,* and Sara Rut Arias Perez1 Department of Anesthesiology and Intensive Care, Hospital Universitario Infanta Cristina, Parla, Madrid, Spain 1

Abstract: Physicians of emergency department should be trained in airway management and be familiar with the algorithms and devices at their hospitals. Whenever possible, a rapid evaluation should be carried out in order to attempt to manage a possible difficult airway. Limiting the number of attempts (maximum of three attempts) to achieve a timely nontraumatic endotracheal intubation is the main goal in airway management. Therefore, it is important to make the first attempt in the best conditions and with a device with the highest likelihood of success in order to prevent airway trauma and progression to a “cannot intubate, cannot oxygenate” situation.

Keywords: Cricoid pressure, Capnography, Difficult Airway, Emergency Department, Failed intubation, FONA, Hypoxia, Oesophageal intubation, RSI, Surgical airway, Videolaryngoscope. INTRODUCTION According to the literature, difficult airway occurs at the emergency department in around 2.4%, 8.5% of the cases [1 - 3]. The most frequent causes are the presence of an anterior larynx, neck immobility and profuse oral secretions, being more common in men (75.5%). It is essential to consider that the risk of encountering a difficult airway is higher outside the operating theatre, with more attempts and therefore, a higher rate of morbidity and mortality as a result of failed intubations, oesophageal intubations, hypoxia and the need for surgical airway management [3, 4]. Corresponding author Alicia Guarnizo Ruiz: Department of Anesthesiology and Intensive Care, Hospital Universitario Infanta Cristina, Parla, Madrid, Spain; Tel/Fax: 0034 911 91 30 00; E-mail: [email protected] *

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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EVALUATION AND PREPARATION OF A DIFFICULT AIRWAY [3, 5] ●

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It is always necessary to carry out a rapid evaluation of the airway using various predictors with the objective of managing a potential difficult airway. Never forget to carry out preoxygenation, whenever possible, through a nasal cannula or mask ventilation. Tracheal tubes of assorted sizes. Capnography should always be available. It is necessary to place the patient in an appropriate position and to have the equipment ready with a known device, and a Plan B in case. Carry out a rapid sequence induction and intubation (RSI) in accordance with the latest consensus (the use of etomidate, ketamine, thiopental or midazolam as inductors, and succinylcholine and rocuronium as NMBAs [6]). Cricoid pressure. Its use is controversial since it has not been shown to completely obstruct the passage of the content from the oesophagus and may make laryngoscopy difficult. The use of RSI is recommended (level C) provided that it does not mean difficulty in ventilation and/or intubation, according to the NAP4 study. The emergency service staff should be continuously trained to deal with difficult airway.

NECESSARY DEVICES AND EQUIPMENT According to the ASA recommendations [7], a difficult airway trolley containing the following elements must be available and should be adjusted to the requirements and availability of each hospital. This must be known by all the staff, immediately available and reviewed periodically. ●

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Rigid laryngoscope blades of alternate design and size from those routinely used; this may include a rigid fiberoptic laryngoscope. Videolaryngoscope (Fig. 1). Tracheal tubes of assorted sizes. Tracheal tube guides. Examples include (but are not limited to) semirigid stylets, ventilating tube-changer, light wands, and forceps designed to manipulate the distal portion of the tracheal tube. Supraglottic airways (e.g. LMA or ILMA of assorted sizes for non-invasive airway ventilation/intubation). Flexible fiberoptic intubation equipment. Equipment suitable for emergency invasive airway access. An exhaled carbon dioxide detector.

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There are numerous studies on rescue devices following failed direct laryngoscopy. Laryngeal mask airway (LMA) has been shown to be an effective alternative with regards to difficulties with in ventilation and/or intubation, with success rates between 53.3% and 98% [8, 9] after a period of training. The principal complication is air leakage. The use of a second generation LMA is recommended (Fig. 2), owing to its ability to prevent aspiration, since it is easy to insert [9, 10] even by untrained personnel [11].

Fig. (1). Different videolaryngoscopes and Macintosh direct laryngoscope.

The use of a videolaryngoscope improves the success rate of intubation and patient’s safety if the personnel have prior training in its use [12 - 14].

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Fig. (2). Second generation LMA, Auragain, Ambu (bit.ly/2o5vkA0).

Those most studied are Airtraq, Glidescope, C-Mac, Pentax and King Vision. It has been suggested that they improve vocal cord exposure and the percentage of glottis opening scores [12]. They are particularly useful in patients who have limited mouth opening [14], while in the first attempt, intubation does not differ [13]. ALGORITHM This chapter proposes an algorithm modified by the difficult airway Society in its 2015 guidelines (Alg. 1) [15]. It should be emphasized that the algorithms must always be adapted to each hospital. CONCLUSION ●

●

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The managment of difficult airway in the emergency department proposes a challenge for the medical personnel. It is necessary to train the personnel regarding how to evaluate the airway and the various existing devices and algorithms. Every emergency department should have a trolley containing difficult airway material at their disposal.

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PLAN A - FACEMASK VENTILATION AND TRACHEAL INTUBATION  CALL FOR HELP  Adequate head and neck position  Preoxygenation  RSI  3 attempts  Machintosh +/- bougie  Videolaryngoscopy

PLAN B - SUPRAGLOTIC AIRWAY DEVICE (SAD)  LMA 2nd gen. insertion  Combitube  Fastrach (Maximum 2 attempts)

Confirm with capnography

Options:  Intubate via the SAD  Surgical airway

PLAN C - FACEMASK VENTILATION

PLAN D - SURGICAL AIRWAY Alg. (1). An algorithm modified by the difficult airway Society in its 2015 guidelines.

CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that this chapter’s content has no conflict of interest. ACKNOWLEDGEMENTS Declared none.

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REFERENCES [1]

Wong E, Ng YY. The difficult airway in the emergency department. Int J Emerg Med 2008; 1(2): 10711. [http://dx.doi.org/10.1007/s12245-008-0030-6] [PMID: 19384660]

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Law JA, Broemling N, Cooper RM, et al. The difficult airway with recommendations for management--part 1--difficult tracheal intubation encountered in an unconscious/induced patient. Can J Anaesth 2013; 60(11): 1089-118. [http://dx.doi.org/10.1007/s12630-013-0019-3] [PMID: 24132407]

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Cook TM, Woodall N, Frerk C. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the difficult airway Society. Part 1: anaesthesia. Br J Anaesth 2011; 106(5): 617-31. [http://dx.doi.org/10.1093/bja/aer058] [PMID: 21447488]

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Goto T, Gibo K, Hagiwara Y, et al. Multiple failed intubation attempts are associated with decreased success rates on the first rescue intubation in the emergency department: a retrospective analysis of multicentre observational data. Scand J Trauma Resusc Emerg Med 2015; 23(1): 5. [http://dx.doi.org/10.1186/s13049-014-0085-8] [PMID: 25700237]

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Law JA, Broemling N, Cooper RM, et al. The difficult airway with recommendations for management, part 2 ,the anticipated difficult airway. Can J Anaesth 2013; 60(11): 1119-38. [http://dx.doi.org/10.1007/s12630-013-0020-x]

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Ollerton JE. Adult trauma Clinical Practice Guidelines, Emergency Airway Mangement in the Trauma Patient, NSW Institute of Trauma and Injury Management, 2007.

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Apfelbaum JL, Hagberg CA, Caplan RA, et al. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the difficult airway. Anesthesiology 2013; 118(2): 251-70. [http://dx.doi.org/10.1097/ALN.0b013e31827773b2] [PMID: 23364566]

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Bernhard M, Gries A, Ramshorn-Zimmer A, Wenzel V, Hossfeld B. Insertion success of the laryngeal tube in emergency airway management. Biomed Res Int 2016; 2016(3619159). [http://dx.doi.org/10.1155/2016/3619159]

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Bosch J, de Nooij J, de Visser M, et al. Prehospital use in emergency patients of a laryngeal mask airway by ambulance paramedics is a safe and effective alternative for endotracheal intubation. Emerg Med J 2013; 31(9): 750-3.

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Saeedi M, Hajiseyedjavadi H, Seyedhosseini J, Eslami V, Sheikhmotaharvahedi H. Comparison of endotracheal intubation, combitube, and laryngeal mask airway between inexperienced and experienced emergency medical staff: A manikin study. Int J Crit Illn Inj Sci 2014; 4(4): 303-8. [http://dx.doi.org/10.4103/2229-5151.147533] [PMID: 25625062]

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Szarpak Ł, Kurowski A, Truszewski Z, Robak O, Frass M. Comparison of 4 supraglotttic devices used by paramedics during simulated CPR: a randomized controlled crossover trial. Am J Emerg Med 2015; 33(8): 1084-8. [http://dx.doi.org/10.1016/j.ajem.2015.04.050] [PMID: 25963675]

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Choi HY, Oh YM, Kang GH, et al. A randomized comparison simulating face to face endotracheal intubation of pentax airway scope, C-MAC video laryngoscope, glidescope video laryngoscope, and macintosh laryngoscope. BioMed Res Int 2015; 2015: 961782. [http://dx.doi.org/10.1155/2015/961782] [PMID: 26161424]

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Choi HJ, Kim Y-M, Oh YM, Kang HG, Yim HW, Jeong SH. GlideScope video laryngoscopy versus direct laryngoscopy in the emergency department: a propensity score-matched analysis. BMJ Open 2015; 5(5): e007884. [http://dx.doi.org/10.1136/bmjopen-2015-007884] [PMID: 25968006]

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Eismann H, Sieg L, Etti N, et al. Improved success rates using videolaryngoscopy in unexperienced

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users: a randomized crossover study in airway manikins. Eur J Med Res 2017; 22(1): 27. [http://dx.doi.org/10.1186/s40001-017-0268-7] [PMID: 28797305] [15]

Frerk C, Mitchell VS, McNarry AF, et al. Difficult airway Society 2015 guidelines for management of unanticipated difficult intubation in adults. Br J Anaesth 2015; 115(6): 827-48. [http://dx.doi.org/10.1093/bja/aev371] [PMID: 26556848]

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CHAPTER 16

An Update on Percutaneous Airway Management Carlos Velayos Amo1,* and Raquel del Olmo Monge1 1

Department of Intensive Care, Hospital Universitario de Fuenlabrada, Madrid, Spain Abstract: The ability to guarantee adequate and quick access to the airway in lifethreatening situations poses a challenge for clinicians who attend critically ill patients. Surgical or percutaneous techniques have an important role in stabilizing patients in such emergency scenarios. Patients who need prolonged mechanical ventilation may benefit from a tracheostomy to avoid complications related to the orotracheal tube. In these cases, tracheostomy must be achieved in the safest conditions to minimize risks for patients. As an alternative to surgical techniques, the use and indications of percutaneous management of the airway are rapidly increasing. In this chapter, percutaneous management of the airway is described. The authors try to clarify the indications and contraindications of this approach and to answer multiple clinical questions, such as is percutaneous tracheostomy better than the surgical approach? Which percutaneous modality is the best? When is the best moment to perform percutaneous tracheostomy in a critically ill patient? Is there any way to reduce complications related to percutaneous techniques?

Keywords: Blue Rhino, Blue dolphin, Cricothyrotomy, Ciaglia, Critical Care, Emergent airway management, Fantoni, Griggs, Intensive Care Unit, Mechanical ventilation, Prolonged ventilation, Percutaneous airway management, Percutaneous tracheostomy, Percutwist, Surgical tracheostomy, Weaning. INTRODUCTION Surgical tracheostomy is a well-known technique, which was first described in ancient times. It used to be the strategy of choice to manage acute respiratory insufficiency when non-invasive strategies were not successful, until direct laryngoscopy was developed and became the gold standard to intubate and stabilize the airway [1]. Nowadays, doctors who treat critical patients still need to be proficient in surgical or percutaneous approach to airway management, because it could be an option when other techniques have failed. Corresponding author Carlos Velayos Amo: Department of Intensive Care, Hospital Universitario de Fuenlabrada, Madrid, Spain; Tel/Fax: 0034 916 00 60 00; E-mail: [email protected] *

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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On one hand, guaranteeing adequate and quick access to the airway in lifethreatening situations (such as airway obstruction or acute respiratory failure when orotracheal intubation cannot be achieved) seems to be a challenging situation for clinicians who attend critically ill patients. Surgical or percutaneous techniques have an important role in the stabilization of patients in such emergency situations [2]. On the other hand, a tracheostomy might be performed in a non-emergency situation. For example, patients who need prolonged mechanical ventilation may benefit from a tracheostomy to avoid complications related to the orotracheal tube. In these cases, tracheostomy must be performed in the safest conditions, in an attempt to minimize the risks for patients [3, 4]. Traditional surgical techniques include cricothyroidotomy and tracheostomy. Both are simple interventions, which can be performed quickly and safely by an expert surgeon. By contrast, for physicians without surgical training or without experience, facing life-threatening situations which involve the airway and associated with a high risk of death or permanent sequelae seem to be some of the most stressful situations in their clinical practice. As an alternative to surgical techniques, percutaneous management of the airway is possible. It was first described by Dr. Pasquale Ciaglia and is based on Seldinger’s technique [5]. At present, anaesthetists are familiar with numerous approaches to airway management using a percutaneous technique from the easiest and fastest one (mini-cricothyr- oidotomy) to more complex forms of percutaneous tracheostomy. All of these techniques have evolved to achieve quick and safe access to the airway, both in emergency and non-emergency situations. Due to this great evolution, percutaneous tracheostomy has become a routine in daily clinical practice for doctors who treat critical patients [6]. The standardization of percutaneous techniques has extended their use and expanded their indications. However, at the same time, anaesthetists need to answer multiple clinical questions, such as is percutaneous tracheostomy the surgical approach? Which percutaneous modality is the best? When is the best moment to perform a percutaneous tracheostomy in a critically ill patient? Is there any way to reduce complications related to percutaneous techniques? The aim of this chapter is to provide a better understanding of percutaneous management of the airway to define indications and contraindications of this approach as well as to guide decisions and answer questions related to these techniques when applied to clinical practice, using the best available scientific evidence.

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TECHNIQUES Percutaneous Cricothyroidotomy Cricothyroidotomy gives clinicians access to the trachea through the cricothyroid membrane, which is one of the most superficial and easily accessible areas of the airway. Due to these circumstances, cricothyroidotomy is a simple and fast technique to get access to the upper airway in an emergency and has a low potential to produce vascular damage if it is located properly. It does not require cervical hyperextension, which is widely known, and should be avoided in patients with a suspected cervical injury. Cricothyroid membrane lies between the thyroid and the cricoid ere are two other variations of Ciaglia cartilages (Fig. 1). In most populations, both the cartilages are easily visualized and palpated, but in obese people, an adequate identification of these structures could be challenging. Proper detection of the cricothyroid membrane is crucial to achieve the technique successfully. A recently published study showed that the overall success rate identifying the cricothyroid membrane by palpation was ≤ 50%, and there were no differences between anesthesia providers and trauma surgeons. Furthermore, there were no significant differences in the success rates identifying the cricothyroid membrane based on either clinical experience or emergency surgical airway experience [7]. Classically, physicians used a surgical technique to perform a cricothyroidotomy. A small incision is made on the cricothyroid membrane, which is later enlarged with a Trousseau tracheal dilator to introduce a tracheostomy tube or a small caliber orotracheal tube (nº 4-5). If the procedure is run by expert surgeons, with the appropriate equipment, it is a secure technique that guarantees rapid access to the airway, gas exchange and secretion´s removal [2]. Besides the surgical approach, there are two variants of the percutaneous approach: cricothyroidotomy with needle, and cricothyroidotomy based on Seldinger’s technique. The first one allows precarious, quick and transient access to the airway whenever, in an extreme emergency, circumstances do not allow the clinician to achieve a cricothyroidotomy successfully. Another scenario where a cricothyroidotomy with a needle is employed is in children with acute respiratory failure and impossibility to obtain good access, in an attempt to improve oxygenation until an optimum approach is obtained [8].

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Thyroid cartylage Cricothyroid Cricoid cartylage Tracheal rings

Fig. (1). Neck Anatomy References.

First of all, the cricothyroid membrane is localized and punctured with an abbocath of size 12-14. Then, the needle is removed and an Ambu bag or a ventilator delivering 100% oxygen is connected. This is achieved either by connecting a 2 or 3 ml syringe without plunger to the cannula and attaching the connection piece of a 6.5 tracheal tube or by connecting a 10 ml syringe without plunger into the cannula and inserting an endotracheal tube with the cuff inflated, as seen in Fig. (2). Nevertheless, the anesthetist must keep in mind that this technique does not guarantee adequate gas exchange and secretion removal, therefore, safer access to manage the airway should be obtained as soon as possible. When a cricothyroidotomy is performed, any of the commercially available sets may be used. Every advanced airway trolley and each resuscitation cart must include one of these sets. All the hospital areas where a critical patient could be located should be provided with one (Intensive Care Unit, Emergency, Recovery Room, etc.) This technique is based on Seldinger’s method, and it is almost as fast as surgical

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cricothyroidotomy. All the sets for percutaneous cricothyroidotomy include a scalpel, which is used to perform the initial incision. Then, a dilator fitted with a number 4 cannula is inserted through the first incision. The dilator is now taken away, and the cannula is placed in the trachea.

Fig. (2). System to ventilate through a vascular catheter (Two Options).

Later, an Ambu bag or a ventilator is connected through a piece to the cannula. Some sets provide a needle to puncture the cricothyroidotomy membrane. A wire is inserted through the needle into the trachea. The needle is then removed, and an adequate dilator and mini cannula are threaded in the wire guide to their proper position. When it is achieved, the wire and dilator are removed, and the cannula stays inside the trachea (Fig. 3). There are no studies comparing surgical versus percutaneous cricothyroidotomy. Accordingly, experts are not able to establish which technique is better in terms of success rate, complications and speed. Our point of view is that, except for an

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expert surgeon using the procedure, the best way to get familiar with the technique is to practice it with cadavers or mannequins, using one of the above mentioned cricothyroidotomy sets. Even though it is a simple technique, it requires a high grade of security to achieve it as soon and as safely as possible because it is always performed under extreme emergency situations.

Fig. (3). Percutaneous cricothyroidotomy technique: a) Small incision in the middle line over the cricothyroid membrane (optional) b) Puncture with a needle to localize endotracheal lumen (air bubbles are observed). c) A guidewire is progressed through the needle. d) Needle is removed, leaving the wire inside the trachea. e) Dilator with the mini-cannula is inserted in the trachea. f) Guidewire and dilator are removed. Mini-cannula is left in the tracheal lumen.

Percutaneous Tracheostomy This technique was first described in 1985 by Dr. Pasquale Ciaglia [5]. He adapted Seldinger’s technique to place a cannula in the trachea without open access, replacing the traditional surgical approach. First of all, the trachea is located with a needle. Then, a wire is inserted through the needle. Later, multiple sequentially larger dilators are inserted over the guidewire to enlarge the stoma. When the stoma is large enough, the tracheostomy cannula is inserted. This technique had great acceptance different commercial sets were developed to perform it, and consequently, it was used by health care providers. In 1990, Dr. Griggs published a modification of Ciaglia´s technique [9]. He replaced progressive dilation catheters, with using instead a specially designed forcep with a hole in the middle. The guidewire is threaded through this hole.

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Using the forceps, pretracheal soft tissues and tracheal space dilated. Then, the cannula is placed in the trachea. This instrument simplifies Ciaglia´s technique because the dilation is performed with only one or two steps, therefore, procedure becomes easier and faster. In 1999, Ciaglia´s technique underwent another modification. A single dilator, which looks like a Rhino´s horn (thick on its base, and progressively thinner) is used to enlarge the stoma instead of multiple dilators [10]. The industry has developed commercial sets called Rhino, due to the shape of the dilator. Nowadays, Rhino´s technique is used all around the world, and it is perhaps the safest and easiest one to learn. It is probably the technique the other percutaneous modalities should be compared to [11]. There are two other variations of Ciaglia´s technique, both are recently developed, therefore there are less evidence and experience among professionals. The first one, called PercuTwist, due to the name of the commercial kit designed to perform it, uses a single step screw-type dilator [12]. The dilator is rotated to make the stoma, which differs from the pressure movement used with Ciaglia´s Blue Rhino. Balloon dilatational tracheostomy (Ciaglia Blue Dolphin) is the second one. The inflation of a modified angioplasty balloon over a guidewire is used to dilate the trachea. Then, the balloon is deflated and the cannula is placed in the trachea [13]. None of these two techniques have demonstrated advantages over the method of Ciaglia Blue Rhino in terms of success rate, timing or complications therefore they are rarely used [11, 15 - 17]. Finally, there is percutaneous access described by Fantoni [18]. It is different from all the methods previously described. Access to the trachea is retrograde. It involves passing the guidewire through the vocal cords after puncturing the trachea. An experimented operator is needed, which showed no benefits when compared with all the other methods [17]. COMPARISON BETWEEN TECHNIQUES The decision to employ any percutaneous access to perform a tracheostomy must be carefully evaluated. The advantages and disadvantages of each are shown in Table 1. The anesthetist needs to keep in mind the patient´s clinical status, operator experience and available equipment. Clinical trials have tried to assess which percutaneous technique has the best results but it is difficult to draw conclusions from them because of their heterogeneity [19]. It seems that Ciaglia’s method, preferably with a single dilator (Blue Rhino), could be the simplest, safest (even with a higher rate of minor hemorrhages) and one of the fastest [11,

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17]. It also seems that, in expert hands, Griggs´s procedure is equivalent in terms of success, safety and duration [20]. Furthermore, when sterilized forceps are used, the costs are reduced as compared with any other techniques. Another conclusion that can be established from the published literature is that Fantoni’s method has a higher rate of failures and severe complications, therefore it should not be considered as the first choice [17]. Table 1. Advantages and disadvantages of each technique to perform a percutaneous tracheostomy. Technique

Advantages

Disadvantages

Ciaglia (multiple dilators)

- Well known and studied - Low complication rate - Multiple sequential dilators ensure that little force and little pressure is required (less risk of posterior wall puncture) - Less tracheal trauma

- Prolonged procedure - Multiple steps: difficult to learn - Multiple manipulations of the guidewire can result in the dislodgement of the wire out of the trachea. - Potential for posterior tracheal wall puncture - Exposes operators to blood spatter - Long straight dilators facilitate posterior tracheal wall laceration - Supraglottic ETT position may result in the loss of PEEP or loss of airway control. - Increases exposure to aerosolized airway secretions

Ciaglia Blue Rhino

- Faster than the classic technique - Single large dilator: risk of tracheal (fewer steps) trauma - Easy to learn - Same problems with positioning ETT - Curved dilator: less risk of above the cords (see above) posterior wall puncture - Widely practiced

Griggs forceps technique - Faster technique - less dilations - Potentially more harmful to the trachea (potentially, the fastest) and soft tissues - The cheapest set - Requires sterile forceps - Less experience than with Ciaglia Cianchi balloon - No risk of injuring the posterior technique (Blue dolphin) wall - No sequential dilators: Only one balloon. - Not much pressure required to place the cannula

- Prolonged procedure - More steps required - Tracheostomy tube is more difficult to pass into the dilated opening - Less experience than with Ciaglia

PercuTwist technique

- No specific protection against posterior wall lacerations or cartilage fractures - Not widely available - No speed advantage over Griggs or Ciaglia single-dilator technique - Less experience than with Ciaglia

- Less risk of injuring the posterior wall - No sequential dilators: Only one step required - Not much pressure required to place the cannula - Single dilator technique

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(Table 1) cont.....

Technique

Advantages

Disadvantages

Translaryngeal (Fantoni) - No pressure through the posterior - Largely unknown technique wall of the trachea - Higher rate of failure - No need for additional operators - Higher rate of severe complications - Relies on the small endotracheal tube to ventilate - Requires additional equipment - Potentially vocal cord damage

Based on this data, experts can affirm that Ciaglia with a single dilator (Blue Rhino) is currently the gold standard technique when a tracheotomy is performed. Any other potential method should be compared to this one, which is considered the best nowadays. Ciaglia with a single dilator is explained in more detail in Fig. (4) [6]. Anatomical references of the neck are shown in Fig. (1).

Fig. (4). Ciaglia Single Dilator (Blue Rhino) Percutaneous tracheostomy technique.

●

Before the Procedure: ❍

Keep patient on 100% FiO2. Ensure adequate sedation and paralysis of the patient. Deflate the endotracheal tube (ET) cuff and withdraw ET under laryngoscopic vision until cuff is visualized just below the cords, then inflate the cuff again. Clean and drape the patient as per protocol.

Percutaneous Airway Management ❍

●

An anaesthetist localizes the site of insertion by palpation (1st-2nd tracheal ring) and obtains an ultrasound to check the trachea´s depth and anatomical structures and to confirm that there are no vascular structures.

During The Procedure: ❍ ❍ ❍

❍

❍

❍ ❍

❍

❍

●

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Infiltrate the skin with a local anaesthetic containing a vasoconstrictor. Make a 2–2.5 cm transverse incision (A) Pass the bronchoscope through the ET tube until the tracheal lumen is visualized. The trachea is punctured with a 14-gauge sheathed introducer needle (with nondominant hand stabilizing the trachea during the process). (B) Tracheal placement of the needle is confirmed by aspirating air bubbles and by direct visualization through the bronchoscope. The needle is now removed, and a guidewire is introduced through the plastic sheath. The first dilation is made with the help of a small tracheal dilator (optional). Single rhino dilator is moisturized with saline and then loaded over the guiding catheter. The whole assembly is then loaded over the guidewire and advanced as a unit into the trachea in a sweeping action. After adequate dilatation, dilator is removed. The tracheostomy cannula with an appropriate adapter is inserted into the trachea over the guiding catheter.

After the Procedure: ❍

❍

❍

The placement of tracheostomy tube is confirmed by direct visualization of carina through the bronchoscope, by auscultation or by EtCO2. Connect the cannula to the ventilator. Secure the cannula. Remove secretions. Obtain a chest X-ray after the procedure.

Nowadays, the main indication for tracheostomy is prolonged mechanical ventilation, followed by otorhinolaryngology disorders [21]. Traditionally, if a patient needed mechanical ventilation for less than 10 days, an orotracheal tube was placed, but if the patient was likely to be intubated for more than 21 days, a tracheostomy was performed. This recommendation has little evidence, based only on experts’ opinions [22]. Studies comparing prolonged orotracheal intubation versus tracheostomy have not shown a decrease in mortality or incidence of pneumonia [23, 24]. However, it

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seems that tracheostomized patients show less damage in vocal cords and tracheal stenosis when submitted to prolonged mechanical ventilation, compared to the intubated population. In addition, tracheostomy provides better access to the oral cavity for cleaning the tracheobronchial toilet. It improves the quality of life of patients because it facilitates communication. It seems to be better tolerated and more comfortable than the orotracheal tube, which allows clinicians to decrease sedation. Finally, it facilitates weaning by decreasing dead space and resistance to air flow [21]. As a consequence of all these findings, studies on the benefit of early tracheostomy (2-5 days after orotracheal intubation versus classical strategy on day 15), have been performed. Early tracheostomy has failed to demonstrate a clear decrease in mortality, pneumonia related to mechanical ventilation rate, ICU stays or laryngotracheal complications. Some trials have shown a reduction in days under mechanical ventilation, however, if it is considered a potential advantage, the number of tracheostomies could be avoided should be taken into account if deferred until the tenth day of orotracheal intubation due to extubation [25, 26]. If a tracheostomy is needed, the presence of contraindications to perform a percutaneous technique (see Table 2) must be ruled out. If there is none, then percutaneous tracheostomy is preferred because, although the incidence of major complications (death, bleeding, pneumothorax) is similar, a lower rate of stoma infection is described with this modality. If any contraindication is present, a surgical procedure is indicated [27]. PREVENTION OF COMPLICATIONS IN PERCUTANEOUS TRACHEOSTOMY BRONCHOSCOPY AND ULTRASOUND Complications Facing Adverse Outcomes Although percutaneous tracheostomy is becoming a routine technique, some risks are associated with it. The complications are mostly related to the patient’s anatomy and clinical situation, but they are also related to the operator´s experience. The actual rate of complications is difficult to establish, however, the anesthetist should not forget that they could potentially be very serious (some of them may lead to death and others are associated with high risk of permanent sequelae, both physical and psychological). These complications include: false passage and fistula generation: innominate artery fistula (most feared, with mortality reaching 100%), tracheoesophageal and tracheocutaneous fistula, tracheal stenosis; infections; hemorrhages; changes in voice, etc [8] (Table 3).

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For this reason, in an effort to minimize the risks, some strategies have been developed to increase the safety of the procedure. Although it is true that its use is not standardized, and that studies show contradictory results, percutaneous tracheostomy is an increasingly common procedure, with support of different security devices, such as bronchoscope [28] or ultrasound guide [29]. Table 2. Contraindications of percutaneous tracheostomy. Absolute

Relative

- Infants

- Enlarged thyroid glands

- Infection at the insertion site

- Presence of pulsatile vessels at the insertion site

- Operator inexperience

- Difficult anatomy (short neck, morbid obesity, limited neck extension, local malignancy, tracheal deviation)

- Unstable cervical spine injuries

- Coagulopathy

- Uncontrollable coagulopathy

- Close proximity to burns or surgical wounds - High PEEP or FiO2 requirements (FiO2 >70%, PEEP >10 cm of H2O) - History of cervical injury or tracheostomy - High riding innominate artery - Radiotherapy to the cervical region in the last 4 weeks - Controlled local infection

Table 3. Complications of percutaneous dilatational tracheostomy. Immediate

Early

Late

- Bleeding

- Tracheal ring fracture

- Subglottic stenosis

- Loss of airway

- Tracheal tube obstruction

- Unplanned decannulation

- Hypoxia

- Paratracheal placement

- Tracheoinnominate artery bleed

- Pneumothorax

- Posterior tracheal wall injury

- Displaced tracheal tube

- False passage

- Pneumothorax/pneumomediastinum

- Delayed healing after decannulation

- Pneumomediastinum

- Surgical emphysema

- Tracheoesophageal fistula

- Posterior tracheal wall injury

- Atelectasis

- Stomal infection

- Esophageal injury

- Raised intracranial pressure

- Scarring of the neck

- Surgical emphysema

- Swallowing difficulty

- Needle damage to bronchoscope

- Permanent voice changes

- Raised intracranial pressure

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Fibrobronchoscope Regarding the first one, it seems to be obvious that direct visualization of the anatomical structures of the airway may reduce complications derived from wrong positioning of the tracheostomy tube, such as false passage or injury to the posterior wall of the trachea. Another potential benefit is the possibility of instilling sclerosing substances through one of the channels of the fiberoptic bronchoscope if any hemorrhagic complication is detected. However, the use of the fibrobronchoscope as a support device poses certain risks by itself. On one hand, the introduction of a fiberoptic bronchoscope in a tracheal lumen reduces the diameter of the trachea lumen, which can lead to hypoventilation. Thus, patients with deep alteration in gas exchange, fragile patients, and those with acute neurological damage should be carefully evaluated before carrying out the technique with bronchoscope assistance. On the other hand, the fibrobronchoscope-related reduction of the lumen of the trachea increases the pressure of the airway, and therefore, the risk of barotrauma becomes higher. It is also well known that when a fibrobronchoscope is used, the duration, complexity and cost of the procedure become higher than when the technique is performed without it. In view of all these considerations, the available evidence does not allow us to give firm recommendations on the generalization of the use of the bronchoscope to reduce the complications associated with a percutaneous tracheostomy. Nevertheless, its use by expert hands and in selected patients could be very helpful to guide the procedure [30 - 32]. Ultrasound The benefit of ultrasound resides in the possibility of detecting anatomical variations and vascular structures adjacent to the puncture area. It is logical to think then, that the number of hemorrhagic events associated with percutaneous tracheostomy should decrease [29]. This fact is even more relevant in obese patients, people with short necks and those with limited cervical extension [33]. In addition, the measurement of the distance between the skin and the trachea helps to calculate how deep the needle should be introduced. Measurement of the tracheal diameter allows to anticipate the size of the tracheostomy tube needed. Real-time visualization of the needle and the wire while being introduced allows the operator to have better control of the structures during the procedure, which

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accounts for a lower risk of damage to the posterior wall of the trachea or thyroid isthmus. The ultrasound transducer is a surface device, which does not reduce the effective ventilatory space, as the bronchoscope does; therefore, the aforementioned complications are not associated with ultrasound. Nevertheless, the anesthetist should not forget that ultrasound is a subjective technique, with great interobserver variability, and a steep learning curve. These circumstances may affect the measurements, results and safety of the procedure. Multiple studies have been published to assess whether the routine use of ultrasound decreases the complications associated with a percutaneous tracheostomy. Although performing a cervical ultrasound has led to a change in the planned puncture site in 25-50% of the cases (depending on consulted series), a reduction in the rate of bleeding has not been demonstrated. According to the available scientific evidence, the widespread use of ultrasound prior to a percutaneous tracheostomy may not be recommended to decrease the number of complications associated with the procedure [34, 35]. With all this information, experts can conclude that, as the number of percutaneous tracheostomies grows, complications associated with the technique are reduced. The techniques and support devices are spreading around the world to increase the safety of around the procedure, such as ultrasound and the use of the bronchoscope. Although the available evidence does not allow to recommend the universal use of these tools, in selected patients with risk factors they could be of great help for those physicians who face the airway management and the potential complications related to it. Their use depends on the operator's ability to use both the instruments [14]. CONCLUSION ●

●

●

Percutaneous techniques are essential to airway management. There are two main scenarios: 1. Life-threatening situations. Failure of all other strategies to get access and stabilize the airway. 2. Patients who need prolonged mechanical ventilation. With the available studies, there is limited evidence to make recommendations. Due to the published data, it can be concluded that percutaneous cricothyroidotomy seems to be the easiest and fastest technique in a lifethreatening situation, when all other strategies have failed. Cricothyroidotomy guarantees an acceptable gas exchange and acts as a bridge to a definitive access to the airway. When a patient is suspected to need prolonged mechanical ventilation, then a

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percutaneous tracheostomy should be done if no contraindication is found. Currently, the preferred method is Ciaglia with a single dilator (Blue Rhino), although this choice should be subjected to the patient´s baseline status, operator´s preference and available material. Therefore, it is recommended that a set of cricothyroidotomy with a minicannula and a kit for percutaneous tracheostomy (Blue Rhino as first option) must be available in all the hospital where airway management is routine or where complications related to it may occur (Emergency, Operating Room, Recovery Room, Intensive Care Unit). An adequate training of the personnel who faces this that kind of a situation is equally important.

CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that this chapter’s content has no conflict of interest. ACKNOWLEDGEMENTS Declared none. REFERENCES [1]

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CHAPTER 17

An Update on Airway Management in Anaesthesia Outside the Operating Room Ignacio Portalo González*, 1, Flor de María Analía Sánchez Díaz2, Paula Martinez Fariñas3 and Eugenio D. Martínez Hurtado4 Department of Anesthesiology and Critical Care Medicine, Hospital Infanta Cristina, Parla, Madrid, Spain 2 Department of Anesthesiology and Critical Care Medicine, Complejo Asistencial Universitario de León, León, Spain 3 Department of Anesthesiology and Critical Care Medicine, Hospital FREMAP Majadahonda, Madrid, Spain 4 Department of Anaesthesiology and Intensive Care, University Hospital Infanta Leonor, Madrid, Spain 1

Abstract: The airway management in the operating room has received a lot of attention during the last years from the anaesthesiologists. However, in recent years there has been a significant increase in the demand for anesthetic care in diagnostic and therapeutic procedures performed outside the operating room. Metzner et al. investigated the main mechanisms of injuries of 87 cases in the United States [1] compared with cases outside the operating room. The most frequent procedure was monitored anaesthetic care, and the most frequent mechanism was adverse respiratory events. The results highlighted inadequate ventilation/oxygenation in 18 cases, difficult intubation in 6 cases, oesophageal intubation in 8 cases and stomach contents aspiration in 3 cases. The majority of the adverse effects were due to excessive sedation manifested by severe respiratory depression. Therefore, it could be concluded that general anesthesia with endotracheal intubation management may be safer than the monitored anesthesia care (MAC) for these procedures.

Keywords: Airway management, Anaesthesia outside operating room, Airway prediction, Aspiration of stomach contents, Algorithms, Cannot intubate - cannot ventilate, Challenge for the anesthesiologist, Difficult intubation, Difficult ventilation, Education for airway management, Emergencies, Infrastructure, Intensive care, Monitored anesthetic care, Neuromuscular relaxants, Organizational aspects, Respiratory events, Remote places, Remifentanil, Videolaryngoscopes. Corresponding author Ignacio Portalo González: Department of Anesthesiology and Intensive Care. Hospital Infanta Cristina, Madrid, Spain; Tel/Fax: 0034 911 91 30 00; E-mail: [email protected]

*

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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INTRODUCTION The 4th National Audit Project (NAP4), an audit of the Anesthetists and Difficult Airway Society [2] provides detailed information on the incidence of major complications in airway management. The most important problems are “difficult or delayed intubation”, “aspiration of gastric contents” and “failed intubation” [3, 4]. Most of the cases of airway management outside the operating room occurred in the emergency and intensive care departments, in which intubation is usually emergent (Fig. 1).

Fig. (1). Intubation in ICU with flexible fibrobronchoscope.

Although there have not been specific analyses of the scenarios in which

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anesthesiologists perform airway management outside the operating room in remote locations, an analysis of this situation confirms the high risk of these procedures but highlights the lack of algorithms, trained personnel, rescue procedures and organizational aspects [4, 5]. This chapter highlights some recent and relevant aspects of airway management outside the operating room. ORGANIZATIONAL ASPECTS The main problems in airway management in faraway places outside the operating room are the difficulty in requesting assistance and help, as well as the limited training and education of airway management of the personnel working in these locations [6]. Therefore, a fast and safe communication system is a prerequisite to ensure available assistance without delay [4, 7]. The available space of the rooms may be small and the access to power lines, gas supply and suction equipment can be complicated. Careful inspection and, if needed, adaptation of the space by the anesthesiology service is essential [8]. Another aspect that is often disregarded is the optimal positioning of the patient before the anesthesia induction. The tables where interventions are performed outside the operating room have limitations to adjust the proper position to manage the airway, as well as to have access to the airway. Last but not the least, to optimize the safety of anesthesia, the entire team should be trained in the management of the difficult airway. ANAESTHETIC TECHNIQUE An anesthetic technique selection between sedation and general anesthesia with a supraglottic device or orotracheal intubation will influence the different scenarios on the management of a difficult airway. In sedation cases, abrupt loss of breath or airway patency could cause the anesthesiologist to end up in a disaster situation. Therefore, the anesthesiologists must always be prepared and have the required equipment available. It is advisable to have one or more additional difficult airway trolleys available with the necessary tools. These should also include invasive airway instruments [5]. A question without consensus is whether the use of muscle relaxants can facilitate ventilation with a face mask. It is more recognized that neuromuscular blockers are useful in cases of difficult ventilation with facial masks and even recommended in patients in a situation of “cannot intubate-cannot oxygenate” (CICO) or if waking up the patient is not possible [9].

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Warters et al. [10] demonstrated that the administration of rocuronium significantly improved ventilation without complications in any of the patients. Another study investigated the use of rocuronium or succinylcholine in patients with normal upper airway anatomy [11]. Rocuronium did not impair mask ventilation, but succinylcholine obtained better ventilation with more dilation of the isthmus of the fauces. Rapid reversal of the neuromuscular block induced by rocuronium with sugammadex has been suggested for the management of a difficult airway (Fig. 2). Nevertheless, in case of a “cannot intubate, cannot oxygenate” (CICO) scenario, it may not be enough to reverse it as this situation can be caused by the multiple manipulations of the airways [12] or drugs.

Fig. (2). Sugammadex and intubation devices.

Even so, anaesthetists must bear in mind that, currently, in the airway algorithms, it is not advisable to perform a neuromuscular blockade and that the objective in ventilation preservation is always the best option to awaken the patient if possible [4]. Total intravenous anesthesia (TIVA) using remifentanil with a combination of intravenous agents, or remifentanil with inhaled agents has

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been widely proposed as an alternative to optimize intubation conditions [13]. The pharmacokinetic profile (rapid onset of action and short elimination half-life, independent of the infusion time) and pharmacodynamic properties (attenuation of the sympathetic and hemodynamics reaction to intubation) support its use in the normal and difficult airway management. The duration is similar to succinylcholine and allows the chance to awaken the patient in difficult scenarios. Nonetheless, the literature remains inconclusive regarding the potential side effects (nausea, vomiting, shivering, muscle pain, sore throat, dizziness, confusion, agitation, hypotension, bradycardia, slowed breathing, muscle stiffness, vocal fold closure, etc.), although some of them may be due to the combination with other drugs, administration time and dosage. DIFFICULT AIRWAY PREDICTION An accurate prediction of the difficult airway constitutes a mainstay in airway management and includes both difficult mask ventilation (DMV) assessment and difficult intubation. This prediction has significant importance in the optimally planification and management of the respiratory tract in remote locations. Langeron et al. [14] identified five risk factors in a prospective study related to difficult mask ventilation. These were: age over 55 years, BMI greater than 26 kg / m2, lack of teeth, history of snoring and presence of facial hair. A high probability of DMV was indicated by the presence of at least two of these factors. In 2004, Han et al. [15] proposed a scale to stratify the ability to perform mask ventilation, including four grades in ascending difficulty. Grade 1 was effective ventilation without the aid of devices, grade 2 was with the help of cannula, grade 3 was inadequate ventilation, unstable or requiring two practitioners and grade 4 was an inability to ventilate. Regarding the predictors of difficult intubation, individual risk factors include Mallampati, head and neck movement, mouth opening, jaw movement, prominent incisors, thyromental distance, sternomental distance, obesity (BMI of 35 kg / m2) as well as a previous history of difficulty in intubation. DIFFICULT AIRWAY ALGORITHMS Difficult Airway Society (DAS) and the American Society of Anesthesiologists (ASA) algorithms are among the most widely accepted guidelines. The last DAS protocol for unforeseen intubation difficulties in an adult non-obstetric patient was published in 2015 [16]. The advantage of the DAS guideline is the use of fair flow charts based on 4 plans:

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Plan A. Mask ventilation and tracheal intubation Plan B. Maintaining oxygenation: supraglottic airway device insertion Plan C. Final attempt at face-mask ventilation Plan D: Emergency front-of-neck access [CICO (cannot intubate/cannot oxygenate) scenario]

The Practice Guidelines for the Management of Difficult Airway by the ASA were updated in 2013 [17], and recognized the introduction of videolaryngoscopes as an initial approach to intubation. The guidelines do not oblige, but should be considered as guides to develop more specific algorithms related to airway management inside and outside the operating room. VIDEOLARYNGOSCOPES Evidence on the use of videolaryngoscopes has been widely increased in the last decade. Videolaryngoscopes are devices that differ slightly in design and function, containing a miniaturized camera to indirectly visualize the glottis. All of them are especially useful in remote locations for managing difficult airways [4]. Although there are no specific studies, there is a considerable amount of clinical evidence to support their use in emergencies [18] or intensive care [19]. There are some devices (Airtraq, King Vision, GlideScope, C-MAC, McGrath MAC, etc.) that have been extensively studied [20, 21] and appeared as extensively potential for use in remote locations (Fig. 3). Nonetheless, there are many other videolaryngoscopes available but their proper use depends on the availability of the center. These devices are classified into three generic categories. The first category is the group with standard Macintosh blades. These devices have the same blade as a standard Macintosh direct laryngoscope and are used by performing the standard intubation technique. This category, includes C-MAC, Intubrite, Mcgrath MAC, etc. The endotracheal tube is inserted with a pre-curved stylet. In the second group, there are devices with angled blades. These devices are inserted over the midline of the tongue until its tip is inserted into the vallecula or posterior to the epiglottis. The endotracheal tube is inserted with a pre-curved stylet because intubation is always viewed indirectly. The most studied devices in this category are GlideScope, D-blade C-MAC, King Vision, Mcgrath MAC Xblade, etc. The third category includes videolaryngoscopes with a channeled blade for the

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tube. They have an anatomical shape and guide channel which directs the endotracheal tube towards the glottis. The devices in this category are the Airtraq, King Vision, etc.

Fig. (3). Airtraq in Africa operation room.

The list of airway devices will continue to grow and new definitions and algorithms will be needed to optimize their use [4]. All these devices have the advantage of being portable, many of them are operated with batteries, and some of them have built-in screens that make them even more compact and portable. ADVANTAGES AND DISADVANTAGES OF VIDEOLARYNGOSCOPES It is important to note that most of these devices improve the visualization of the glottis; nevertheless, a good glottic view does not always result in a better success intubation rate [22], and correct training in its use is necessary to solve the difficulties that may appear. The advantages of videolaryngoscopes are the most evident in the management of the difficult airway, to resolve difficult intubations under visual control and to limit the number of failed attempts. There is evidence of the use of some of these devices by untrained personnel and paramedics, in a prehospital environment, emergency department or ICU [18, 19]. Studies that compared the use of GlideScope versus C-MAC obtained similar success in intubation in the first attempt (82 versus 84%, respectively). Otherwise,

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C-MAC was better compared to standard Macintosh laryngoscopy, leading to a higher proportion of successful intubation. In ICU, GlideScope improves visualization compared to direct laryngoscopy with novice users; however, it does not result in improved intubation [23]. The strongest predictor of intubation failure with GlideScope was DOWHUHG neck anatomy. In another study, a better success rate of intubation on the first attempt was described with the use of C-MAC compared to standard laryngoscopy [24]. The use of GlideScope was recently revised in a systematic review [25]. Compared to conventional direct Macintosh laryngoscopy, the use of GlideScope in patients with normal airways applies significantly less force to the soft tissues of the oropharynx. In the context of a predicted difficult airway, the use of CMAC videolaryngoscopy was better than the classical methods, that resulted in more success in the first attempt. Finally, videolaryngoscopy could also offer a potential use for awake intubation in patients with predicted difficult airways (Fig. 4).

Fig. (4). Awake intubation using Airtraq + Flexile Fibrobronchoscope (full video in bit.ly/2MIUwKw).

Nonetheless, in cases of blood or secretions, which is often the case in the emergency department, these devices perform poorly, but always better than fiberscope and at least equal to the classical direct laryngoscopes. This fact is a really stressed scenario.

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CONCLUSION ●

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Airway management outside the operating room is challenge for the anesthesiologist. Aspects such as organization, infrastructure and lack of trained personnel should be considered. Therefore, a thorough evaluation of the airway remains a cornerstone in anesthesia practice, even when monitored anesthetic care without airway instrumentation is provided. Differences in pharmacological regimens such as remifentanil use or avoidance of neuromuscular relaxants are of particular interest in these scenarios. The use of videolaryngoscopes has offered a new tool for airway management, which improves visualizations, but does not always result in successful intubation. The wide variety of available devices makes it difficult to compare them and multicenter trials are still needed to justify their use. A potential danger is that the training and experience is insufficient when needed in an emergency setting due to the large number of devices. Therefore, it is advisable to use only one or two devices in each anesthesia service to ensure optimal management and experience.

CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that this chapter's content has no conflict of interest. ACKNOWLEDGEMENTS Declared none. REFERENCES [1]

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Souter KJ, Davies JM. Diversification and specialization in anesthesia outside the operating room. Curr Opin Anaesthesiol 2012; 25(4): 450-2. [http://dx.doi.org/10.1097/ACO.0b013e3283557a05] [PMID: 22691620]

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Engelhardt T, Weiss M. Difficult mask ventilation and muscle paralysis. Anesthesiology 2013; 118(4): 994. [http://dx.doi.org/10.1097/ALN.0b013e3182874659] [PMID: 23511535]

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Warters RD, Szabo TA, Spinale FG, DeSantis SM, Reves JG. The effect of neuromuscular blockade on mask ventilation. Anaesthesia 2011; 66(3): 163-7. [http://dx.doi.org/10.1111/j.1365-2044.2010.06601.x] [PMID: 21265818]

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Ikeda A, Isono S, Sato Y, et al. Effects of muscle relaxants on mask ventilation in anesthetized persons with normal upper airway anatomy. Anesthesiology 2012; 117(3): 487-93. [http://dx.doi.org/10.1097/ALN.0b013e3182668670] [PMID: 22846679]

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Curtis R, Lomax S, Patel B. Use of sugammadex in a ‘can’t intubate, can’t ventilate’ situation. Br J Anaesth 2012; 108(4): 612-4. [http://dx.doi.org/10.1093/bja/aer494] [PMID: 22287458]

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Fotopoulou G, Theocharis S, Vasileiou I, Kouskouni E, Xanthos T. Management of the airway without the use of neuromuscular blocking agents: the use of remifentanil. Fundam Clin Pharmacol 2012; 26(1): 72-85. [http://dx.doi.org/10.1111/j.1472-8206.2011.00967.x] [PMID: 21771056]

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Langeron O, Masso E, Huraux C, et al. Prediction of difficult mask ventilation. Anesthesiology 2000; 92(5): 1229-36. [http://dx.doi.org/10.1097/00000542-200005000-00009] [PMID: 10781266]

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Han R, Tremper KK, Kheterpal S, O’Reilly M. Grading scale for mask ventilation. Anesthesiology 2004; 101(1): 267. [http://dx.doi.org/10.1097/00000542-200407000-00059] [PMID: 15220820]

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Frerk C, Mitchell VS, McNarry AF, et al. Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults. Br J Anaesth 2015; 115(6): 827-48. [http://dx.doi.org/10.1093/bja/aev371] [PMID: 26556848]

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Apfelbaum JL, Hagberg CA, Caplan RA, et al. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2013; 118(2): 251-70. [http://dx.doi.org/10.1097/ALN.0b013e31827773b2] [PMID: 23364566]

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Mosier J, Chiu S, Patanwala AE, Sakles JC. A comparison of the GlideScope video laryngoscope to the C-MAC video laryngoscope for intubation in the emergency department. Ann Emerg Med 2013; 61(4): 414-420.e1. [http://dx.doi.org/10.1016/j.annemergmed.2012.11.001] [PMID: 23374414]

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Niforopoulou P, Pantazopoulos I, Demestiha T, Koudouna E, Xanthos T. Video-laryngoscopes in the adult airway management: a topical review of the literature. Acta Anaesthesiol Scand 2010; 54(9): 1050-61. [http://dx.doi.org/10.1111/j.1399-6576.2010.02285.x] [PMID: 20887406]

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Paolini JB, Donati F, Drolet P. Review article: Video-laryngoscopy: another tool for difficult intubation or a new paradigm in airway management? Can J Anaesth 2013; 60(2): 184-91. [http://dx.doi.org/10.1007/s12630-012-9859-5] [PMID: 23233395]

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Rothfield KP, Russo SG. Videolaryngoscopy: Should it replace direct laryngoscopy? a pro-con debate. J Clin Anesth 2012; 24(7): 593-7. [http://dx.doi.org/10.1016/j.jclinane.2012.04.005] [PMID: 23101777]

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Griesdale DE, Chau A, Isac G, et al. Video-laryngoscopy versus direct laryngoscopy in critically ill patients: a pilot randomized trial. Can J Anaesth 2012; 59(11): 1032-9. [http://dx.doi.org/10.1007/s12630-012-9775-8] [PMID: 22932944]

[24]

Noppens RR, Geimer S, Eisel N, David M, Piepho T. Endotracheal intubation using the C-MAC® video laryngoscope or the Macintosh laryngoscope: a prospective, comparative study in the ICU. Crit Care 2012; 16(3): R103. [http://dx.doi.org/10.1186/cc11384] [PMID: 22695007]

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Griesdale DE, Liu D, McKinney J, Choi PT. Glidescope® video-laryngoscopy versus direct laryngoscopy for endotracheal intubation: a systematic review and meta-analysis. Can J Anaesth 2012; 59(1): 41-52. [http://dx.doi.org/10.1007/s12630-011-9620-5] [PMID: 22042705]

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CHAPTER 18

Anesthesiologist’s Role in Supporting NonAnesthesiologist Airway Provider Practice: Emergency Department and Intensive Care Units Cristina Gil Lapetra1,*, Jossy C. Salazar Aguirre1, José Olarra Nuel1, Beatriz Bolzoni Muriel1 and Marta Solera Toledo1 Department of Anesthesiology and Critical Care Medicine, University Hospital of Fuenlabrada, Madrid, Spain 1

Abstract: The high complication rate following inadequate airway management and its fatal consequences sometimes call for a cross-national comparison to understand different approaches in different settings. Anaesthesiologists have long been considered experts in Airway Management (AM), notwithstanding other medical professionals are frequently solicited to perform such procedures outside Operating Rooms (OR), in some cases without adequate training.

Keywords: Airway management, Blind nasotracheal intubation, Cricothyroid membrane, Difficult airway, Emergency Room, Laryngoscopy, Paramedical, Simulation, Tracheal intubation, Training. INTRODUCTION A literature review including several European and North American countries revealed multiple practices associated with airway management techniques by non-anesthesiologist medical staff outside Operating Rooms (OR). Lately, the question arises whether it is the responsibility of anesthesiologists to train Emergency Room (ER) staff in order to perform Airway Management (AM) or not [1]. Role failure outside OR differs across countries. According to the sources reviewed, nearly half of the regular procedures were carried out by Emergency Physicians (EP), whereas only one third was performed by anesthesiologists, (19 percent were performed by both jointly), consequently, the responsibility of acute Corresponding author Cristina Gil Lapetra: Department of Anesthesiology and Intensive Care, Hospital Universitario de Fuenlabrada, Madrid, Spain; Tel/Fax: 0034 916 00 60 00; E-mail: [email protected] *

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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airway management often falls into the hands of non-anesthesiologists. This is frequently the case in the United States, United Kingdom and Canada. Conversely, countries in northern Europe, as well as Spain, have different handlings. It is a fact that most of the papers reviewed were authored by emergency departments, corresponding to countries where these activities are often carried out by EPs and paramedics. Anesthesia literature is nonetheless non-abundant. Airway management, like any other technique, requires continuous learning. Skills and competencies are to be upgraded regularly. Training must, therefore, be systematic and so must be the completion of the technique. Training programs are the key, along with the number of patients treated and the organization and structure of facilities. EVOLUTION OF AIRWAY MANAGEMENT ANESTHESIOLOGISTS’ FUNCTIONS

AND

NON-

AM in emergency services is higher in the United States, Canada and United Kingdom; indeed, the majority of all the Tracheal Intubations (TI) are executed in these services by EPs. Training of EPs comprises Rapid Sequence Induction (RSI) and the use of Neuromuscular Blockade (NB). In the early 1970s, AM consisted of Orotracheal Intubation (OI) for cardiac arrest patients. Alternatively, awakened patients were treated by Blind Nasotracheal Intubation. Spontaneously-breathing patients would require the presence of an anesthesiologist. EPs became progressively involved in AM during the 1980s, executing advanced airway techniques, including RSI, even as a pre-hospital regular technique. As AM practice spread to become prevalent, the anesthesiology community expressed its concern. Induction with high doses of sedation and without muscle blockage was more frequently performed, increasing the risk of complications. Since the early 1990s, EPs in the United Kingdom, the United States and Canada successfully accomplish RSI with a complication rate similar to that of anesthesiologists [2]. HEALTHCARE SYSTEMS’S ORGANISATION ACROSS COUNTRIES Most of the scientific papers reviewed were published in the United Kingdom, where more homogeneous core training exists (Fig. 1), although, there is limited evidence.

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Fig. (1). Simulation training in AnestesiaR.org, Difficult Airway Management International course.

In the United Kingdom, basic instruction for EPs enforces longer training periods, along with the ER staff fully involved in AM. They execute most of the emerging tracheal intubations [3]. Anesthesiologist assistance is required for patients exhibiting difficult AM (polytraumatized, burned, face and neck injuries patients). EPs commonly go through three to six months in Anesthesia Department and Critical Care Units (although they may go beyond). Pre-hospital ES are thereby carried out jointly by paramedical staff and EPs, under the supervision of Anesthesia Department staff. Evidence of RSI management with adequate use of neuromuscular relaxants and other anesthetic drugs dates to the early 1990s [4, 5]. Likewise, in the United States and Canada, most of the tracheal Intubations in Emergency Department (ED) are taken care of by EPs [6]. Meanwhile, prehospital emergency in the United States is led by paramedical staff with ED remote assistance, as needed. Flying squads anesthetic support is available too. Northern European countries show different courses of action. In Scandinavian countries, tracheal intubations are mainly the responsibility of anesthesiologists. Pre-hospital ED may count upon a helicopter´s fleet (with an anesthesiologist on board), assisted by ground ambulance paramedical staff [7, 8]. Conversely, Central European countries, such as Austria and Germany, do not require proficient AM skills to work in the ED [9].

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A study published by The Scandinavian Journal of Trauma, Resuscitation and Emergency (2017) depicting descriptive quality control techniques, evaluated outcomes and excellence performance of training offered to Austrian Emergency Medical Services (EMS), both pre-hospital and intra-hospital. This article concluded that there had been increase in lawsuits following failed intubations and higher rate of complications [10, 11], which seemed to be the reason for such a scientific activity. In parallel, data was collected to help justify extra funding of training programs. This study sought to illustrate EPs rotation in Anesthesia Department, including scheduled operating room, over a period of three months with a follow-up of skills for the next ten years, improved the outcomes. The observed results were satisfactory in terms of the skills developed. Moreover, intubation rates reached over 60 TIs per year, confirming the need for continuous learning skills. In Germany, EMS training is quite similar to comparable poor outcomes of Emergency AM. In contrast, a study published by the UH in Bangkok [12] revealed the lack of AM training of EPs. According to this study, rapid sequence intubations fall consequently into the hands of anesthesiologists. Tracheal Intubations (TI) often seem to be carried out without anesthetic drugs by Emergency Physicians, insufficiently trained. The complication rate is similar to that of the considered studies, that reported the number of mild complications, such as dental and soft tissue injuries, which increased probably due to the lack of neuromuscular blockade. Globally, all the revised publications conclude that the fewer the TI performed at pre-hospital and intra-hospital emergency per year, the harder to acquire a robust AM, along with adequate periodical training. Similarly, without a minimal number of TI at ED settings, it is very difficult not only to achieve acceptable AM but also to maintain it in the absence of periodical training. The overall number of TI to achieve a 95% rate of success is estimated to be roughly 50 [13] (200 Tis for some authors). In a similar manner, evidence proves that robust training followed by a regular upgrade in operating rooms allow for the most inexperienced physicians to achieve a rate of success in intubation over 95% [14]. Indeed, satisfactory training in AM is concomitant to successful neuromuscular blockade and RSI. Rotation in scheduled operating rooms coordinated by anesthesiologist staff is the key to acquire skills [15]. REVISITING THE CASE IN SPANISH HEALTHCARE FACILITIES In Spain, each hospital applies a different protocol (Fig. 2). In small and medium facilities, when no anesthesiologist is available, EP controls the airway. In bigger

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hospitals ER have specialized trained staff, either the anesthesiologist or the Intensive Care physician. Practices vary; in ER, there is the most rapid sequence induction for acute and critically ill patients. In Critical Care units, the difficult airway may require specific technical support from the anesthesiologist.

Fig. (2). Simulation training in AnestesiaR.org, Difficult Airway Management International course.

In Fuenlabrada University Hospital (HUF), AM training supervisor is in charge of the Anesthesia Unit, which organizes technical workshops for the hospital staff involved in AM. Technical lectures are given by registrars and trainees receive hands-on practices with models regarding the use of direct laryngoscope and different supraglottic devices. Trainees initiate with the technical use of manikins, receiving training in small groups (5 interns in average). At a later stage, they are requested to assist in OR for 8-hours shifts to perform both tracheal intubation and the use of supraglottic devices. Along with these technical workshops, trainees from other medical specialties may be admitted to scheduled operating rooms during 4 to 8 weeks, in order to learn advanced airway technical support; most of them, are Critical Care, ENT or General Surgery residents, who have been admitted as pre-hospital emergency groups. A special 3-weeks protocol has been designed for them (Table 1). The issues discussed along with the course include the management of induction

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drugs and hemodynamic changes in healthy and critically-ill patients. By the end of this period, a total of 50 TI and 40 Laryngeal Mask (LM) intubation should be performed by each trainee who are ready to deal with neuromuscular blockade and safely perform RSI. Table 1. Prehospital rotatory protocol.

Lectures

- Airway Anatomy. - Ventilation. - Airway Management Techniques. Different Devices. - Difficult Airway Algorithm. - Induction and Anesthesia Maintenance. Physiology and Pharmacology.

Operating Room

- Vascular Access. - Patients Airway Examination. - Induction of Anesthesia. - Bag-mask-valve Ventilation. - Direct Laryngoscopy. - Videolaryngoscopy. - Tracheal Intubation. - Laryngeal Mask. - Use of Additional Devices (gum elastic bougie). - Rapid Sequence Induction. - Knowledge and practical use of Different Ventilation Modes. - Transport Ventilators Airway Assessment. - Evaluation Exercise.

BACKGROUND AND SKILLS REQUIRED TO ACHIEVE SUCCESSFUL RAPID SEQUENCE INTUBATION (RSI) Correct AM goes beyond intubation. A number of elements are the key to achieve satisfactory RSI. ●

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Identifying when to intubate a patient. An indication for induction of anesthesia and TI must be made with spontaneously breathing patients. Always identifying a difficult airway, expect for non-anticipated difficult airway. Call for help when necessary. Proper pre-oxygenation, as well as adherence to difficult airway algorithms. Correct use of bag-manual-valve ventilation. Correct management of supraglottic devices, such as LMA, ensuring a safer situation where intubation is not an option. A good knowledge of indications and contraindications of rapid sequence induction. Special emphasis must be put to cardiovascular drug side-effects during the induction of emergency anesthesia. Identify failed intubation. After successful intubation hypo and hyper-ventilation must strictly be avoided.

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Failing to consider the above key factors may lead to intubation failures among paramedical staff more frequently. Fullerton et al. raised the question whether non-anesthesiologists should perform pre-hospital RSI [16]. RSI can be performed safely in critically-ill patients by non-anesthesiologists, provided appropriate training and supervision are available. The clinical condition of the patient determines the possibility of immediate complications after RSI [17]. The training and ability of the operator will determine the options for the patient. Nevertheless, it is difficult to ascertain the number of cases necessary to attain sufficient experience to successfully handle the entire RSI process [18]. OTHER POTENTIAL OBSTACLES Despite adequate training programs, complications in AM may always come forth (for which no written reports exist). The number of cricothyrotomies remains higher in the ER than in the operating room. This may have to do with criticallyill emergency patients. However, some authors realized that laryngoscopic vision corresponded to higher Cormack grades for non-anesthesiologists [19, 20], leading to more manipulation of the airway and worse outcomes. Improvements in laryngoscopic techniques would decrease the number of failed intubations and its consequences, such a surgical airway. Poor use of laryngeal masks and combitube is common to all the sources reviewed. Better and more frequent use could avoid surgical airway. Whether it is due to the lack of knowledge in the management of supraglottic devices or not, is uncertain [21]. Carley et al. described a new “tailored-drill” for failure in RSI intubation in the emergency room [22]. Since patients in these settings are critically ill, the time of procedure and AM are both challenging circumstances in case of the difficult airway (Fig. 3). Compared with DAS unexpected difficult airway (Fig. 4), it should be placed on the box right after the patient wakes up and surgery should be delayed. ROLE OF SUPRAGLOTTIC AIRWAY DEVICES IN EMERGENCY SITUATIONS Airway management does not necessarily mean endotracheal intubation, the goal is to maintain oxygenation. Different guides have become the gold standard in addressing the urgent response to the inability to oxygenate and ventilate, which are the Supraglottic Airway Devices (SAD). Tracheal intubation is a relatively complicated and risky procedure for non-anesthetist personnel, such as paramedics [23], and ERC guidelines recommend that the airway should be secured within 30 secs [24].

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Furthermore, as far as paramedics are concerned, non-anesthetists and other EM staff should be trained to use SAD as a rescue device in intubation situations or when ETI is considered inappropriate [25, 26]. Supraglottic Airway Devices can generally be inserted without interrupting chest compressions and efforts to treat reversible causes for cardiac arrest (e.g., pleural decompression of tension pneumothorax) [25]. However, SADs do not completely protect the airway from gastric insufflation, regurgitation and aspiration. Second-generation SADs offer greater protection against aspiration than the first-generation devices and should be recommended in failed intubation during a rapid sequence induction [26]. NAP4 identified the potential advantages of second-generation devices in airway rescue and recommended that all the hospitals should have them for both routine use and rescue airway management [27], and it is recommended that Emergency Medical Services (EMS) should have them too. When clinical circumstances and provider competence allow, the SAD can be converted to a definitive tracheal tube, reflecting a stepwise approach to airway management involving multiple techniques during a single resuscitation [24]. DISCUSSION AM must be well-known not just in operating rooms and critical care but also in any setting within the hospital boundaries, besides emergency departments. Because of the high level of serious complications and the elevated morbidity and mortality rates derived from unexpected airway management [28], providing adequate training to practitioners is important, which is concluded by all the explored sources about implications from Anesthesia Departments in both training and technical support. Training should cover rotatories in the operating room, as well as workshops with manikins and simulators. This should be settled under formal protocol in all those settings where there is none yet. Regarding training, it is essential to start the use of bag-hand-valves to ventilate a patient. It also seems basic to recognize a possible difficult airway and call for help when needed. To achieve 95 percent rate of success in the first-attempt Tracheal Intubation (TI), at least a total of 50 TI must be completed. The skills are expected to decline early after initial training, therefore, a minimum of 60 TI per year should be performed to allow acceptable management. For the laryngeal mask, at least 40 insertions need to be fulfilled to achieve the first successful attempt in 86 percent of the cases and the second in 96 percent of cases [29].

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The knowledge of supraglottic devices will certainly make a big difference, although it is dependent on the healthcare facility resources.

Fig. (3). Carley's Algorithm. From: Rapid sequence induction in the emergency department: a strategy for failure [22] (bit.ly/2P1TSoS).

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Fig. (4). Difficult Airway Society difficult intubation guidelines: an overview. Difficult Airway Society 2015 guidelines for the management of unanticipated difficult intubation in adults. (From: bit.ly/2PxodMY).

Nevertheless, it is still believed to be a faster option for handling when a prior high-level of airway management is confirmed (among anesthesia interns and even interns from different specialties, it has been found to be a faster learning process than direct laryngoscopy). Again, recognizing a possible difficult airway and calling for help when needed are the basic steps. Adequate instruction is fundamental for emergency physicians to identify a possible difficult airway and decide when to call an anesthesiologist. Ultimately, the responsibility falls upon the in charge of the unit, though synergies must be facilitated between anesthesia and emergency departments to foster robust training and support [30]. In the United States, nearly half of the patients have had regular quality assurance checks in ED patients’ intubation. In general results are satisfactory. CONCLUSION ●

In many settings, anesthesia assistance is still poor, improved links and different

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specialties would ensure correct training and support. Closer cooperation between the two specialties is needed. Besides good AM training, it is also important to be able to take over the management after successful intubation. The audit of these processes should be mandatory to ensure that training is adequate and appropriate. The use of simulators for training could be an option.

CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that this chapter's content has no conflict of interest. ACKNOWLEDGEMENTS Declare none. REFERENCES [1]

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Timmermann A, Russo SG, Eich C, et al. The out-of-hospital esophageal and endobronchial intubations performed by emergency physicians. Anesth Analg 2007; 104(3): 619-23. [http://dx.doi.org/10.1213/01.ane.0000253523.80050.e9] [PMID: 17312220]

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de Oliveira Filho GR. The construction of learning curves for basic skills in anesthetic procedures: an application for the cumulative sum method. Anesth Analg 2002; 95(2): 411-6. [PMID: 12145063]

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Graham CA, Munro PT. Airway management in the accident and emergency department. Anaesthesia 2000; 55(8): 814. [http://dx.doi.org/10.1046/j.1365-2044.2000.01629-7.x] [PMID: 10947705]

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Carley SD, Gwinnutt C, Butler J, Sammy I, Driscoll P. Rapid sequence induction in the emergency department: a strategy for failure. Emerg Med J 2002; 19(2): 109-13.bit.ly/2P1TSoS. [http://dx.doi.org/10.1136/emj.19.2.109] [PMID: 11904254]

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CHAPTER 19

An Update Management

on

Out-of-Hospital

Airway

Alfredo Serrano-Moraza1,* and Armando J. Munayco Sánchez2 Servicio de Urgencias Médicas Summa 112, Madrid, Spain Unidad Médica Aérea de Apoyo al Despliegue de Madrid (UMAAD Madrid), Ejército de Aire, Madrid, Spain 1 2

Abstract: Emergency Management of the Airway (EMA) may become a major challenge in the prehospital setting, in part because of differential and specific characteristics of Patient, Pathology and Environment. Sometimes, these procedures will be part of the initial resuscitation efforts, even in respiratory or cardiac arrest scenarios. Historical and preliminary articles show an increased incidence in airwayrelated complications in the prehospital. Most of this variability depends on the distinct comparison between different Prehospital Emergency Medical Services (EMS) and sources, different personnel origin, educational programs, level of skills, etc. The idea is to reduce these important differences to promote safety as the main goal.

Keywords: Advanced Life Support, Cardiopulmonary Resuscitation, CPR, Difficult airway, Emergency Medical Services, EMS, Endotracheal intubation, ETI, High-qualified intubation, High-quality CPR, Out-of-hospital, Prehospital, Prehospital Emergency Medicine, Rescue Support. INTRODUCTION In the prehospital arena, the place where the patient loses health and, frequently, needs advanced care, Emergency Medical Services (EMS) face many different situations threatening the patient's life. Each of these scenarios will be able to house different combinations between Patient, Pathology and Environment PPE level of complexity, making it unique and difficult to repeat [1, 2]. In some of them, Emergency Management of the Airway (EMA) may become a major challenge, in part because of differential and specific characteristics (Table 1) [3]. Corresponding author Alfredo Serrano-Moraza: Servicio de Urgencias Médicas Summa 112, Madrid, Spain; Tel/Fax: 0034 91 338 75 55; E-mail: [email protected] *

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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In order to find relevant evidence, a preliminary search on PubMed®-Medline (1966-2018) and the Cochrane Database of Systematic Reviews combining the Boolean sequence (“Airway Management”[Mesh]) AND (“Emergency Medical Services”[Mesh] OR “Out-of- Hospital Cardiac Arrest”[Mesh]) with the high quality evidence-search filter (meta-analysis [pt] OR randomized [ti] OR randomized controlled trial [pt] OR systematic [sb] OR review [pt] OR guidelines [ti] OR guideline [pt] OR Prospective studies [mh] OR Retrospective studies [mh]) was performed. Preliminary data are shown in Table 2. Table 1. Differential and specific characteristics of Emergency Management of the Airway in the Prehospital setting. (*) Adapted from its own source [3]. Patient

Pathology

Environment

Operator / Team

Airway Devices

P

P

E

O

D

Always Patient often hosts a Usually performed at A single operator performed critical pathology, home, on the streets must, under an the origin of the or, perhaps, inside an simultaneously, take emergency emergency request ambulance control of indication. resuscitation and Sometimes in airway management minutes after the first contact

Most devices are actually not designed for prehospital work

Always consider patient in full stomach

Some patients have Patient may be Emergency providers Some devices´ a previous difficult entrapped, crushed or have a behaviour may depend airway. in a reduced or heterogeneous on environmental Anyway, any confined place education profile, conditions. anatomic learning curve and e.g.: endotracheal abnormality will expertise tubes flexibility increase difficulty in depends on laryngoscopic view temperature variations and performance (summer/winter) (e.g.: obesity, pregnancy, etc.)

Often unknown previous diseases, allergies, surgeries and treatments

Contaminated, Hot and cold Occasionally, you New electronic devices traumatized or environments, adverse will enjoy the only may stop working or bloody airway may meteorology, poor clear chance to malfunction under worsen airway illumination, noise isolate the airway extreme or hostile management level, fumes, etc. may (e.g.: facial trauma environments conditions interfere patient with edema, bloody resuscitation and airway, etc.) airway control

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(Table 1) cont.....

Patient

Pathology

Environment

Operator / Team

Airway Devices

P

P

E

O

D

Difficult airway incidence is increased (Expected / Unexpected)

Some environments may present additional risks, specific hazards and/or a special complexity.

Usually, portable vacuum aspirators are not powerful enough

Table 2. Data results from PubMed® preliminary search. Pubmed/Cochrane Results

Filtered Results

Metaanalysis

28

12

Randomized studies RCTs

171

Reviews*

579 (43 systematic)

29

Guidelines

93

Prospective studies

564

-

Retrospective studies

605

(*) any kind of review

BASIC PRINCIPLES In general terms, about the EMA in the prehospital setting, it must be emphasized: As described, most of the airway management procedures will be performed under emergency situations. This factor, alone, will be able to increase previously known patient morbi-mortality. Sometimes, these procedures will be part of the initial resuscitation efforts. Even under respiratory or cardiac arrest scenarios. The patient´s related condition (e.g., major trauma, acute myocardial infarction, respiratory failure, etc.) may also have the worst prognosis on its own. As a result: you will have to control the airway and ventilate the most critical patient in the most critical situation, in order to transport the patient under the most stable condition as possible, to reach critical care technique or for survival. Besides providing care, prehospital teams must be engaged in the control of additional risks from the environment to increase patient's and emergency responders´ safety and security. Historical and preliminary articles show an increased incidence in airway-related complications in the prehospital setting. Most of this variability depends on the

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difficult comparison between different Prehospital Emergency Medical Services (EMS) and sources [4] (Table 3). Table 3. Models of Prehospital Emergency Medicine PhEM in the world. Model Name

Characteristics

Worldwide Countries

Paramedic model

Emergency Medical Services EMS with paramedics/EMTs in ambulances. Occasionally, nurses RN, often alone. Most of them with on-line telephone medical supervision (e.g.: NAEMSP).

USA, UK and Commonwealth-related**

Medical hospital model (Franco-German model)

This physician-staffed is a multi-tier system Central Europe composed of basic EMS providers with similar (Germany, France, etc.)*** training to an EMT as well as intermediate providers with skills and training similar to that of an AEMT or paramedic. The last tier is physician staffed ground vehicles or helicopters. Requirements are not standardized but usually include a minimum of two years of completed residency training**. Doctors and nurses, in-hospital trained, share activity between hospital wards and the Prehospital

Prehospital-based model Medical, nurses and technical personnel from and in Euromediterranean the prehospital or Third model (mICUs, HEMS, etc.)

Mediterranean countries. Spain is the model

Note 1: Adapted from its own source [3]. Note 2: This Table is an oversimplification. Models often coexist in time and geography. ** They may coexist with models with flight nurses and/or doctors (physicians on-board) in helicopter care. ***Jacobs PE et al. [17]. EMT: Emergency Medical Technician. NAEMSP: National Association of Emergency Medical Professionals.

Probably because of different qualifications of EMS teams, unexpected difficult airway (DA) ranges from 5% in the physician-based model to 13% in the paramedic one. Drug-assisted RSI, not always available in the paramedic model, may also account for it [1 - 7]. In selected models, high-risk endotracheal intubation (ETI) in medical helicopters by anesthesiologists showed similar results to the rest of studies with physicians on-board [3, 8, 9]. In addition, there may be an inconsistency in the first versions of DA definition from the American Society of Anesthesiologists (ASA), in particular, for the prehospital environment [10]. This is one of the reasons that could explain the variability results of DA incidence and publication. Many of the old results are, probably, inaccurate.

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AIRWAY MANAGEMENT STATE OF THE ART Standardization of techniques and open literature barriers is part of the key to modern prehospital work. It shares knowledge and experience between services and models worldwide, in order to provide safety and reduce morbi-mortality. A few years ago, prehospital educational programs and skills training were a new implementation full of different plans, approaches and heterogeneous protocols. First unified efforts came from the hand of Cardiopulmonary Resuscitation (CPR) International Guidelines in the nineties. Unfortunately, not all the areas followed this way. Nowadays, no author will ignore the scientific guidelines and experience in airway management from associations such as ASA, DAS, SAM, etc. Nevertheless, prehospital is a fertilized field for heterogeneity in all these areas, not only because of the different prehospital models, but from the specific characteristics of personnel origin, educational programs, level of skills, etc. The idea is to reduce these important differences to promote safety as the main goal. According to the available evidence, numerous series of patients agree that the operator's experience is a major factor in success rates [3, 11 - 15]. In a systematic review, Lecky et al. [16] presented data from 3 RCT out of 452 studies, carried out in an urban non-traumatic prehospital environment. The first one found a non-significant survival disadvantage in patients randomized to receive a physician-operated ETI versus a combi-tube (RR 0.44). The second trial detected a non-significant survival disadvantage in patients randomized to paramedic intubation versus an oesophageal gastric airway (RR 0.86) [16]. New accumulated evidence suggests that prehospital ETI success ranges from 69% to 98.4% [17]. Described variations in training, education and procedures may, in part, explain it as shown in Fig. (1). But, perhaps, some questions may arouse. First of All: Is there any Evidence about ETI Success Depending on the Model? As said, most of the studies emphasize differences between operators´ education, experience and level of proficiency. In a meta-analysis from 38 out of 1838 studies, Crewdson et al. [18] found an overall ETI success of 0.953, 0.917 for non-physicians vs. 0.988 for physicians (p= 0.003). This is one of the first significant evidence studies on this subject.

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Fig. (1). Emergency Airway Management.

But, What is the Main Cause, the Model or the Experience? Studies with poor ETI success rates are frequently related to low levels of training and skills. Some of them suggest a direct relation between airway training attempts and ETI success [11]. Many scientific societies have recognized this is a major challenge worldwide. Most EMS must reinforce this area [11]. Therefore, while paramedic national standards require a minimum of 5 intubations for a license, German physicians need 25-50 ETI and the ACGME talks about 35 ETI attempts for training [19]. In contrast, many anesthesiology programs may require more than 1.000 ETI for in-hospital work [17]. Ancient studies about paramedic training suggested that 20-25 ETIs were required to achieve an overall success rate of 90% in their learning curve [2]. In a recent, more controlled study, Kim et al. [20], after two years´ review of CPR video clips in an urban Emergency Department ED, estimated that more than 240 experiences were required to achieve a 90% success rate of highly qualified ETI.

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Is RSI Safe Enough to Achieve ETI? Fouche et al. [21] included 83 studies in a meta-analysis comparing the ETI skills of physicians (Ph) vs. non-physicians (NoPh). Results show successful intubation 99% (Ph) vs. 97% (NoPh). First-pass FP RSI success data were 88% (Ph) vs 78% (NoPh). On the other hand, the Ph group had a lower prevalence of adverse events. However, the NoPh group had a lower prevalence of hypoxia and esophageal intubations. A global analysis did not find reliable differences between Ph and NoPh groups for adverse events. Talking about Safety, What is the Hallmark? Definitely, EMA is mandatory in the Prehospital. But, is ETI really necessary? Such an important question was proposed by Shafi et al. [22] after knowledge of preliminary data from the National Trauma Data Bank suggesting that prehospital ETI correlated with a higher incidence of mortality. Since then, many studies have been conducted in this area. However, security was not, usually, the main objective of them. Restrictive selection criteria have forced us to present the only specific meta-analysis found. Indeed, most of the studies talk about success rates and safety, but not exactly about safety as a priority. It can be admitted this could be a non-true discussion. In 2012, Lossius et al. performed a comprehensive meta-analysis in 58 out of 1070 studies, showing that physicians have significantly fewer pre-hospital ETI failures than non-physicians. This difference persists when non-physicians have access to drug-assisted RSI: 0.991 and 0.955, in favor of physicians (P=0.047) [23]. Then, is There any Advantage between ETI and Some Alternative Devices? Some meta-analysis collected studies suggest that patients with Out-of-Hospital Cardiac-Arrest (OHCA) who receive ETI by EMS are more likely to obtain Recovery of Spontaneous Circulation (ROSC) (OR 1.28), survive to hospital admission (OR 1.34), and survive neurologically intact when compared to supraglottic devices (SAD) (OR 1.33). There were no statistic differences in survival to hospital discharge (OR 1.15) [24]. On the other hand, a meta-analysis conducted by Hubble et al. compared the pooled estimated success rate of different alternative devices from 35 out of 2.005 studies, and a total of 10.172 prehospital patients. The results are as follows: King LT had the highest insertion success rate, 96.5% (71.2%-99.7%); esophageal obturator airway-esophageal gastric tube airway (EOA-EGTA) 92.6% (90.1%-

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94.5%); pharyngeotracheal lumen airway (PTLA) 82.1% (74.0%-88.0%); Combitube 85.4% (77.3%-91.0%); laryngeal mask airway (LMA) 87.4% (79.0%92.8%); Needle cricothyrotomy had a low success rate, 65.8% (42.3%-83.59%); and surgical cricothyrotomy had a much higher success rate, 90.5% (84.8%94.2%), considered the preferred percutaneous rescue airway [25]. A different meta-analysis from the same author and source compared 117 oral ETI vs 23 nasal ETI studies, in a total of 57.132 prehospital patients, with and without drug assisted intubation DFI or RSI and a good interobserver agreement (kappa 0.81). Success rates are: overall non-RSI/non-DFI oral ETI, 86.3% (82.6%-89.4%); Oral ETI for non-cardiac arrest patients, 69.8% (50.9%-83.8%); DFI 86.8% (80.2%91.4%); and RSI 96.7% (94.7%-98.0%). For pediatric patients, the paramedic oral ETI success rate was 83.2% (55.2%-95.2%). The overall nasal ETI success rate for nonphysician clinicians was 75.9% (65.9%-83.7%). The historical trend of oral ETI reflects a 0.49% decline in success rates per year. For nonarrest patients, DFI and RSI appear to increase success rates. Across all clinicians, NTI has a low rate of success, raising questions about the safety and efficacy of this procedure [26]. As it has been repeated in other chapters, airway management does not necessarily mean endotracheal intubation, maintaining oxygenation as the goal. Tracheal intubation is a relatively complicated and risky procedure in the hands of non-anesthetist personnel such as paramedics [27]. Therefore, as far as prehospital concerns paramedics, non-anesthetists and other EM staff, they will be trained in to use SAD as a rescue device in intubation situations or when ETI is considered inappropriate, difficult or impossible [28, 29]. First-generation SADs do not completely protect the airway from gastric insufflation, regurgitation and aspiration, but Second-generation SADs offer greater protection against aspiration and intubation fail during a rapid sequence induction [30]. NAP4 identified the potential advantages of second-generation devices in airway rescue and recommended that all hospitals have them available for both routine use and rescue airway management [31], and it will also be recommendable in the prehospital settings. When the situation requires it, the SAD can be converted into a definitive airway management device. This exemplifies the gradual approach to airway management that involves multiple techniques during a single resuscitation [28].

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It is Really Needed to Emphasize the Confirmation of the ET Position? Many different techniques have been used in the prehospital to confirm the correct placement of the endotracheal tube ETT, with different fortune results. From the beginning, some limitations suggested capnography may be a “soft” gold standard [32, 33]. Trying to solve this problem, Li performed an interesting two-phase study [34]. From 2.192 ETI, he found capnography predictive values: S 93%, E 97%, FN failure 7% (tube in the trachea when capnography shows esophagus) FP 3% (tube in esophagus when capnography shows the trachea), the last one is the most dangerous situation. In the same study, after 4.602 ETI from the National Emergency Airway Registry, 4% of emergency intubation attempts resulted in accidental esophageal intubation, 10% in no trauma CPR scenarios [34]. Therefore, as capnography –and no other single method- may show a nonnegligible mistake rate, the author emphasizes on the simultaneous use of multiple methods of tube placement confirmation to increase safety [34]; experts in this area also agree [3]. AIRWAY MANAGEMENT IN CPR By definition, if any field is defined by Emergency Airway Management (EAM), it is CPR. Most of the available evidence often rely on the registry and observational designs. More evidence studies are needed to determine the optimal approach to EAM in CPR but have not yet been performed [35]. On the other hand, so much data are frequently hidden or masked under studies of global survival rates between Basic and Advanced Life Support [36]. Besides, this pioneering field and frequent updates are open access and full of valid and reliable literature [37 - 40], even in the raw version available for researchers at the Consensus on Science and Treatment Recommendations CoSTR [36, 41]. Besides this frequently updated bibliography, Jeong et al. [42] published in a meta-analysis 10 out of 1452 studies comparing 17.380 patients who received advanced airway management vs. 67.525 in basic airway management. The advanced group had lower rates of survival (OR 0.51) than the basic one. ETI subgroup vs. basic group had no significant association with respect to survival (OR 0.44). There were no statistically significant differences in neurologic recovery between advanced and basic groups (OR 0.64). Another study conducted by Fouche et al. (meta-analysis from 388.878 patients)

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showed a similar significant association against advanced airway management [43]. This had lower short-term survival rates against overall basic maneuvers (OR 0.84), ETI (OR 0.79) and SAD (OR 0.59). Subgroup analysis of only adult, non-trauma and successfully intubated did not modify these results at a significant rate. An interesting discussion in these and other studies suggests that part of the observed differences can be attributed to many identified factors: trauma vs. nontrauma, adult vs child, successful ETI vs. not, etc. that make patient jumping between subgroups, etc [42]. Similar results are found by Tiah et al. in a systematic review [44]. In this scenario, the delay in performing EMA may play a central role. Future studies must control possible bias from no-flow and low-flow times impact on ROSC and neurological recovery rates [17, 41, 45]. AIRWAY MANAGEMENT IN MAJOR TRAUMA As with CPR, Prehospital advanced EMA in Major Trauma in one of the most controversial areas in recent years. DFI and RSI are now considered the standards of care to avoid death or hypoxic brain injury [17]. Many studies show that evidence bases for advanced airway management are inconsistent, contradictory and rarely report all key data. On the other hand, poorly performed advanced airway management is harmful, and less-experienced providers have higher intubation failure rates and complication rates. International guidelines carry many common messages about the system requirements for the practice of advanced airway management [46]. Most of the pre-hospital and emergency in-hospital RSI has been modified from standard RSI techniques to improve patient safety [46]. In the meta-analysis from Bossers et al. [47], from 6 out of 733 studies (N 4.772 patients), prehospital ETI under limited experience had an increased double odds mortality (OR 2.33), especially in traumatic brain injury, while trained personnel had no increased mortality (OR 0.75). Once again, the experience is shown as a strong significant predictor of mortality (p = 0.009). In a curious systematic review, Ollerton et al. [48] posed different considerations about the relations between potential cervical spine injury and DA management for emergency ETI in trauma adults in the ED. Even in the absence of quantitative results, this is an interesting article to read [46].

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RECENT ADVANCES IN EMERGENCY AIRWAY MANAGEMENT Probably the key in the prehospital for survival and damage control, many areas and decisions are waiting for new evidence in EMA. Between them, airway management by first responder (lay person), assessment of the value of spontaneous breathing as a valid option, new preoxygenation devices, mouth to mouth ventilation, bag-mask ventilation efficiency, oro- and nasopharyngeal airways usefulness, no-DFI or no-RSI evaluation, new advances in EMA in major trauma, etc. [17, 49]. Clinicians and researchers must be aware of the need for new practical questions to be answered. For example, as a sample, in a meta-analysis of 6 studies (and a total of 1.822 patients), Binks et al. found a significant reduction in the incidence of desaturation (RR 0.76, p 0.002) and critical desaturation (RR=0.51, p=0.01) when apneic oxygenation Ap-Ox was implemented. There was also a significant improvement in first pass intubation success rate (RR 1.09, p 0.004) [50]. CONCLUSION ●

●

●

Endotracheal intubation success in the prehospital depends on multiple factors. According to the available evidence, operator's experience is one of the most important factors in success rates. First experiences in Emergency Airway Management (EMA) came from the hand of Cardiopulmonary Resuscitation (CPR) International Guidelines in the nineties,which have now been updated. Unfortunately, not all the areas have followed this way. Major Trauma EMA was the second revisited challenge. In recent years, new Anesthesia-related guidelines emphasize scientific basics and experience in EAM from associations such as ASA, DAS, SAM, etc. New devices are waiting just around the corner, some of them from the hand of electronics. Many of them are not included here due to a lack of experience and evidence-based references.

CONSENT FOR PUBLICATION Not Applicable. CONFLICT OF INTEREST The authors confirm that the content of this chapter has no conflict of interest. ACKNOWLEDGEMENTS Declared none.

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CHAPTER 20

An Update on Airway Management in High-Threat Environments Armando J. Munayco Sánchez1,*, Alfredo Serrano Moraza2, Jose Ramón Rey Fedriani3 and Alberto J. Hormeño Holgado1 Unidad Médica Aérea de Apoyo al Despliegue de Madrid (UMAAD Madrid), Ejército de Aire, Madrid, Spain 2 Servicio de Urgencias Médicas Summa 112, Madrid, Spain 3 Unidad Militar de Emergencias (UME), Primer Batallón de Intervención, Madrid, Spain 1

Abstract: Emergency management of the critical patient in some specific scenarios is a difficult job, not only related to the patient's condition but also to austere and hostile environments. Working as a medical provider in this arena, specific procedures, techniques and treatments must be reconsidered as per the most important factor, i.e. the presence and characteristics of a major threat over you.

Keywords: Critical patient, Emergency management, Hostile environments. INTRODUCTION Emergency management of the critical patient in some specific scenarios is a difficult job, not only related to the patient's condition but also to an austere and hostile environment. Such a task can be a major challenge when medical providers become combat targets themselves. The available data shows that medical treatment facilities around the world in combat or violent areas are often under threat and frequently attacked. With the passage of time [1], in 2017, 20 countries in Africa and the Middle East suffered assaults and abductions; having 322 attacks, with 242 deaths and 229 injured [2]. Only in the first three months of 2018, 13 countries were attacked, with 221 deaths and 261 injured [3]. Working as a medical provider in this arena, specific procedures, techniques and Corresponding author Armando J. Munayco Sánchez: Unidad Médica Aérea de Apoyo al Despliegue de Madrid (UMAAD Madrid), Ejército de Aire, Madrid, Spain; Tel/Fax: 0034 916 274 710; E-mail: [email protected] *

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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treatments must be reconsidered as the most important factor, i.e., the presence and characteristics of a major threat over you. Therefore, experts must address some considerations regarding logistics, safety, security, and the basis of care. The airway management is included within these proposals. Before starting, it must be encouraged that regular procedures should not be performed in these situations of ruling out any of these principles. MEDICAL SUPPORT Medical treatment facilities are generally not close to the battlefield. It is in mountain areas, offshore, disaster areas or battle field where victims suffer not only conventional injuries and diseases but also specific wounds due to combat epidemiological characteristics or violent mechanisms. In most cases, there are no medical facilities in these scenarios, so medical providers must develop special strategies, capabilities, and resources to reach patients at the right time and in the right way; retrieving them for critical and noncritical care to make possible an efficient recovery as healthy as possible for daily life. From the combat experience, it can be interesting to follow the “10-1-2 rule” [4, 5]. Not more than 10 minutes from the injury to first care, applied by battle comrades or self-aid. Not more than 1 hour for advanced life support (ALS) and not more than 2 hours to reach medical facilities with damage control surgery and critical care capability. One hour for the latter, if possible. In recent years, new findings have come to light after improvement in medical skills provided by medics or paramedics to combat casualties, a fact that is changing the “golden hour” concept about ALS. In a conscious aimed-at-survival effort, all personnel involved in medical care are increasing their abilities in combat evidence-based medicine. In these operational scenarios, medical evacuations (medevac) become of special interest based on the following considerations: ● ● ● ●

The threat is always present. Patients are under extreme weather conditions and at remote access. Medical treatment facilities (surgery and blood) are often far away. Most injuries and diseases are time-dependent.

Once on board, the victim is in the evacuation asset with little time as possible, while medical techniques are being performed on the way. This is the so-called “en-route care” [5].

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Usually, the best medical evacuation assets are aerial. This point enforces that flight medical providers must master techniques in resuscitation damage control, ALS, critical care support, etc. Most of the NATO countries have Emergency Medicine in their doctrinal corp. For example, Spain [6], France, Netherlands, Czech Republic, Italy, EE.UU., UK, Germany, etc. [7, 8]. COMBAT CASUALTY CARE The main causes of casualties are related to gunshot wounds and blast injuries. Nevertheless, difficult roads and terrains and vehicle characteristics also have a significant impact on motor vehicle crash and trauma injuries and deaths. In this medical doctrine, NATO countries share common procedures, frequently updated from publications and experiences from the battlefield. In this way, highlighting the pioneering experience of the US Armed Forces in the “Tactical Combat Casualty Care” [9] program, three phases and different approaches are described: 1. Care under fire (CUF) or non-permissive phase. CUF talks about the idea of working under an imminent direct fire or environmental threat. In this phase, the only clinical care after taking cover is the tourniquet application, if possible, by self-aid or other comrades. 2. Tactical field care (TFC) or semi-permissive phase. In this phase, under an indirect secondary threat, minimal basic care against life-threatening injuries will be performed with small medical supplies and quick procedures, in order to prepare for medical evacuation. The casualty collection point is likely to be within this zone. The first task in this phase is always focused on maintaining tactical awareness. 3. Tactical evacuation phase (TEP). TEP is related to “en-route-care”. Additional medical supplies and qualified personnel may be required, but focused on combat or trauma management. Even though it is considered a safer phase, it is still under permanent threat. “MARCH [9]” or “CABCDE” mnemonic protocols describe the way to manage combat casualties in the second and third phases: M A R C H

C A B C D/E

MASSIVE BLEEDING CONTROL AIRWAY MANAGEMENT RESPIRATION / BREATHING CIRCULATION / SHOCK HEAD / HYPOTHERMIA

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ROTARY WING EVACUATIONS The role of rotary wings in evacuations will never be emphasized enough in these environments. Time should not be wasted on the land in combat or high threat areas. Therefore, rule “scoop and run playing” is making shorter the time to approach surgery and blood products. So, how can we work properly on these assets? Just consider two lines: Flight Security Doctrinal corps must be known and applied when working around aerial assets in order to avoid accidents. These skills must be developed by medical crews on a daily basis especially by: ● ● ●

● ● ● ●

Flight personnel equipment (guns, protections, radios, helmets, lanyard, etc.) Get patients ready in a proper way to evacuation. Choose the right point with proper signalling and support for helicopter approaching operations. Casualty handling procedures with litter and/or ambulatory patients. Secure and attach crew and patients into the helo. If necessary, perform in-flight duties under safety rules. Prepare patients to alight and handover to the medical facilities.

According to James Reason´s theory, flight safety may follow a model of confronted walls (layers of defences) with weak holes [10]. When these holes are aligned with the wall, the accident occurs. The walls are organization, supervision, conditions and safety work. In this model, knowledge of the flight security doctrine keeps these defence walls in full in addition to human factors (teamwork, leadership, etc.). Aeronautical Environment Some special conditions in rotary-wing evacuations must be underlined (Fig. 1). Changes in partial oxygen pressures may affect patients at high altitudes. Medical providers must anticipate physiological signs and symptoms to offset low PaO2. As Boyle-Mariotte law states: under constant temperature, the gas pressure is inversely proportional to gas volume. Therefore, when helicopter flights over 8.000 feet, in gas anatomical compartments, the volume is increased as pressure is reduced. It could have an effect on the lungs, gastrointestinal tract, etc. developing tension pneumothorax among other conditions. Electronic medical devices may

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malfunction because of these changes. The medical crew must counteract this incident or use proper devices to accomplish their tasks. Accelerations are really hard in tactical flight close to the ground and following the orography. This type of flight is usually under vibrations, noise, darkness, extreme temperatures and inner wind (flying with the doors open). All these factors make the task even more difficult. Considering all the above-mentioned facts, it is clear to say that medical crews face many adversities to manage these kinds of casualties. Such difficulties enforce an improvement of regular procedures and standards to achieve the best medical quality during the evacuation.

Fig. (1). Austere environmental factors in rotary wing evacuation. Own elaboration.

CASUALTY CARE IN CIVILIAN SETTINGS Violence-related attacks take place in the US, Europe, etc. causing multiple casualty incidents (MCI) with a variable number of victims. These events share some characteristics with combat operation theatres. Therefore, war procedures may be useful in these scenarios, as well. The serious problem of MCI in the US with active shooters has forced the

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development of some strategic protocols. One of them is the Tactical Emergency Casualty Care [11], with similar technical procedures from the battlefield experience but with some important differences: ● ● ●

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These events may be surprising in a peaceful zone. Management belongs to the law enforcement corps. Emergency services are not military, they do not have ballistic protections nor guns. Citizens are not used to thinking and training regarding violent incidents. Casualties are not combatants and can be old people, babies, children, pregnant women, etc. Many of these casualties may have previous diseases.

Depending on the countries, injury mechanisms might be different. Daily press and mass media show active shooters in the US, stab wounds, cars or trucks in Europe or in the Middle East, etc. You must know your own environment. These current threats and some others are the main reasons to develop specific procedures for an organized civilian response under military philosophy. In order to achieve the best results, three phases in civilian management of violent attacks are described [11]: 1. Direct threat: according to the basic principles, civilian responders must: 1. Find protection first, by running far away from the hot zone. 2. Second: look for hiding and 3. Fight against the threat. Afterward, they should alert 112 (911) or a similar number and finally, take care of oneself, move as far from the direct threat zone as possible. Law enforcement corps will run to this zone to combat the hostile action. In this area, the only care allowed, if tactically feasible, is the application of tourniquets. 2. Indirect threat: civilians should always be alert and follow similar steps as indicated in the direct threat phase. They will follow the authorities´ orders to stay in safe areas. However, sometimes they can treat casualties. After bleeding control with direct pressure or improvised tourniquets, citizens can protect the airway as follows: Unresponsive breathing patient: apply chin lift or jaw thrust manoeuvre and/or recovery position. Breathing severe casualties: try to get the best position to protect breathing: chin lift, jaw thrust or recovery position. ❍

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During the first minutes, under the threat, unconscious patients will be placed in the recovery position, even without a breath check [12].

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Law Enforcement members must be trained in additional skills about bleeding control sets (tourniquets, hemostatic bandages, and dressings). For example, they can improve patient care with a nasopharyngeal airway. When checking victims for breathing, they can assess the application of vent patches over open and/or sucking chest wounds. They must continue checking the patient breathing patterns because of the possibility to develop a tension pneumothorax. Emergency Medical Services (EMS) will develop their own protocols from similar procedures, trying to optimize scarce medical supplies, reduce on-scene times and improve survival rates. AIRWAY MANAGEMENT Airway management has just been introduced regarding citizens and law enforcement units. These recommendations are useful for EMS as well. In areas under high threat, EMS providers must apply the described similar techniques and shared with the rest of responders, in order to gain access to the evacuation asset as soon as possible: chin-lift or jaw-thrust manoeuvre, recovery position, nasopharyngeal airway, and other fast techniques. They must always keep situational awareness trying to perform their duties under safety and evacuate this zone. In this sense, the focused phase is the evacuation with en-route-care, shortening the transport time, while basic techniques are being applied. During the evacuation, the most difficult transport asset is the rotary-wing one. Medical crews will deal with limited space, accelerations, vibrations, changes in PO2 and gas volume with altitude, etc. to provide care (Fig. 2). ●

Organization: you must practice with the team trying to avoid movements around the patient and take medical supplies you need in your hands.

Always be ready to reach medical equipment and supplies considering the critical condition of the patient, as time is life.

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Fig. (2). Medical supplies and devices in tactical rotary-wing evacuations. Own elaboration.

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Airway Opening: if no contraindications, perform the chin-lift or jaw-thrust manoeuvre and apply the nasopharyngeal airway, if necessary.

When evacuating a brain-injured patient, the injured head should be placed inside the cockpit. In a conscious victim without sedoanalgesia indications, casualties must be placed in the best position to keep on breathing: recovery position, semisitting, etc. If necessary, cricothyroidotomy must be performed in flight. ●

Intubation: this is the gold standard. Besides conventional technique, face to face in situ intubation must be provided.

In these scenarios, in the Spanish medical forces, the Airtraq device has been a very useful tool: it needs small space in confined areas and it resists under hard conditions. Other devices, as Glidescope, have also been used in these settings successfully by the Italian and the American forces. Rapid sequence intubation (RSI) procedure must be mastered (Fig. 3) [13]. Supraglottic Airway Devices (SAD) could help you as useful alternatives [8]. Although intubation may be the absolute method to secure the airway, SADs have been used successfully for short air evacuations. Second generation SADs are easier to use, safer than the first-generation ones and provide more alternatives [14]. In the absence of endotracheal tube cuff, an i-Gel can be considered as a significant device to overcome the varying changes of pressure and volume by altitude. Accelerations and vibrations may provoke supraglottic devices to be pulled out, forcing you to frequently check its proper position. - Sedoanalgesia (Sedation and Analgesia): the rotary- wing is not a good environment for procedural sedation, making it a difficult and a major challenge during evacuations. In this scenario, Bispectral Index (BIS) can be an invaluable

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tool for continuous sedation level assessment, avoiding under dosage or overdose by using the right drug amount.

Fig. (3). Rapid Sequence Induction and Intubation procedure in an austere environment. Own elaboration. 2nd version [13].

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Bolus doses are useful in the first moments and for short evacuations. Sometimes, it could be better to use Ketamine or benzodiazepines in small doses to avoid respiratory depression. BIS could be used in the army field, and there are some data emerging, but more studies are needed to provide solid evidence from clinical trials. - Mechanical Ventilation: if possible, use devices able to compensate for changes in pressure / volume and PaO2 [15]. If not, to avoid ventilation-induced lung injury (VILI), ventilator settings must follow casualty outputs: fraction of inspired oxygen FiO2, pulse-oximetry SpO2, end-tidal carbon dioxide ETCO2 lung compliance, different airway pressures, continuous monitoring of performed mechanical ventilation (curves and loops) and continuous blood arterial gas analysis. • Controlled modes are recommended due to accelerations and vibrations. Volume control mode is a good way to start. • Monitor breathing for possible new onset of tension pneumothorax immediately after take-off. CONCLUSION ●

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Working in austere environments under high threats will force you to modify conventional casualty management and airway techniques. Safety is paramount. Medical care priorities are always behind tactical alert awareness and safety considerations. In an indirect threat zone, immediate responders (citizens) can also contribute to control basic airway management: chin lift or jaw thrust manoeuvre, recovery position and the best position to keep breathing when conscious. In the same zone, first responders (Law Enforcement Corps) will perform similar manoeuvres, adding some devices, such as the nasopharyngeal airway. In this zone as well, EMS will only perform minimal procedures, and reserve advanced care for the evacuation phase. “Scoop and run playing”. While flying, keep all your medical supplies by hand. They should be as small as possible, and with few pieces. It is mandatory to keep in mind and train to perform a safe Rapid Sequence Induction (RSI) and an Intubation procedure. New electronic devices have been developed to compensate for changes in a hypobaric environment.

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CONSENT FOR PUBLICATION Not Applicable. CONFLICT OF INTEREST The authors confirm that the content of this chapter has no conflict of interest. ACKNOWLEDGEMENTS Declared none. REFERENCES [1]

World Health Organization. Switzerland: [updated 6th July 2018; cited 6th July 2018].

[2]

World Health Organization. Switzerland: Attacks on health care dashboard. Reporting period: 1 January to 31 December 2017 [updated: 2017; cited 6th July 2018].

[3]

World Health Organization. Switzerland: Attacks on health care dashboard. Reporting period: 1 January to 31 March 2018 [updated: 2018; cited 6th July 2018].

[4]

Tien H, Beckett A, Garraway N, Talbot M, Pannell D, Alabbasi T. Advances in damage control resuscitation and surgery: implications on the organization of future military field forces. Can J Surg 2015; 58(3) (Suppl. 3): S91-7. [http://dx.doi.org/10.1503/cjs.001815] [PMID: 26100784]

[5]

NATO Standardization Office (NSO). Allied joint Medical Support Doctrine(AJP-410-B V1). Nueva York: NATO 2015.

[6]

Orden DEF/2892/2015, de 17 de diciembre, por la que se establecen las especialidades complementarias del Cuerpo Militar de Sanidad. 979-83, Madrid: BOE nº 6, 7th January 2016.

[7]

Committee of Chiefs of Military Medical Services in NATO (COMEDS).

[8]

Henlin T, Sotak M, Kovaricek P, Tyll T, Balcarek L, Michalek P. Comparison of five 2nd-generation supraglottic airway devices for airway management performed by novice military operators. BioMed Res Int 2015; 2015: 201898. [http://dx.doi.org/10.1155/2015/201898] [PMID: 26495289]

[9]

TCCCCommitte. United States of America: Tactical Combat Casualty Care for All Combatants Guidelines [updated: 2015; cited 7th july 2018]. CoTCCC; [about 2 screens].

[10]

Robert SH, Gary R. High Reliability in Health Care. UT Southwestern. Parkland: UTSW, Parkland Health and Hospital System 2016; p. 9.

[11]

Tactical emergency casualty care committee. United States of America: Tactical emergency casualty care guidelines for first care providers [updated June 2016; cited 9th July 2018]. CoTECC; [about 2 screens].

[12]

Pajuelo Castro JJ, Meneses Pardo JC. Evita una muerte, está en tus manos [homepagefor internet]. Spain: Guía para el manejo de heridos en incidentes armados con múltiples víctimas y tiradores activos [updated: November 2017; cited 9th July 2018]. Evita una muerte, está en tus manos; [about 2 screens]. Available from: https://evitaunamuerte.es/wp-content/uploads/2017/11/Gui%CC%81aavanzada-actualizada-nov.-2017.pdf

[13]

Munayco Sánchez AJ, Guiote P. Figura Secuencia de intubación rápida en entonos hostiles Avances en el conocimiento de la vía aérea Manejo extrahospitalario. 1st ed., Madrid: SEDAR 2013.

[14]

Frerk C, Mitchell VS, McNarry AF, et al. Difficult Airway Society intubation guidelines working

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group. Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults. Br J Anaesth 2015; 115(6): 827-48. [http://dx.doi.org/10.1093/bja/aev371] [PMID: 26556848] [15]

Hernández Abadía A, Gil Heras A, López López JA, Ríos Tejada F. Mechanical ventilation in hiphobaric atmosphere – aeromedical transport of criticallly ill patients. Combat Casualty Care in Ground Based tactical Situations: Trauma Technology and Emergency Procedures. 16-18.

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CHAPTER 21

An Update on Extubation Management Eugenio Daniel Martinez-Hurtado1,*, Miriam Sanchez-Merchante2, Nekari de Luis Cabezón3, Javier Ripollés Melchor1 and Alicia Ruiz Escobar1 Department of Anaesthesiology and Intensive Care, University Hospital Infanta Leonor, Madrid, Spain 2 Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Fundación Alcorcón, Madrid, Spain 3 Department of Anesthesiology and Critical Care Medicine, Hospital Universitario de Basurto, Bizkaia, Spain 1

Abstract: Although extubation is often considered a mere intubation reversal, it is actually a potentially dangerous process where there is a transition from a controlled to an uncontrolled situation. Anatomical and/or physiological airway changes secondary to airway manipulation or related to the surgical procedure, as well as other factors as hemodynamic instability and time pressure, contribute to a situation that can become more challenging than intubation for the anaesthesiologist. Management of the airway during this phase of anaesthesia may be more complex than induction and requires careful planning that is frequently overlooked.

Keywords: Bronchospasm, Complications, Extubation, Intubation, Laryngospasm, Morbidity, Mortality, Mortality, Planification, Reintubation, Safe, Strategy, Severe outcomes, Videolaryngoscopes. INTRODUCTION Intubation and extubation are two of the most important processes in airway management in anesthesia, both during surgical and non-surgical procedures. It may represent a critical moment, especially when encountering a difficult airway, which makes preparation for potential complications essential. Extubation has an important role in the optimal patient recovery after surgery. It is as essential as intubation and therefore requires proper planning [1]. In every case, * Corresponding author Eugenio D. Martinez-Hurtado: Department of Anesthesiology and Intensive Care, Hospital Universitario Infanta Leonor, Madrid, Spain; Tel/Fax: 0034 911 91 80 00; Email: [email protected]

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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it poses a risk for a potential reintubation due to extubation manoeuvre failure, which ould put the patient in a vulnerable and potentially dangerous situation. Respiratory complications after tracheal extubation are associated with significant morbidity and mortality. Planning is a critical component of a successful airway management strategy. Process improvement in this clinical area is still needed, as extubation failure may lead to severe outcomes. Extubation may cause laryngospasm, bronchospasm and elevated intracranial pressure in predisposed subjects [2]. However, it is often disregarded as a mere reversal procedure of intubation [3]. According to data from the NAP4 audit, serious complications during extubation following anaesthesia occurred in 13% of cases, with a mortality rate of 5% [4]. According to the American Society of Anesthesiologists (ASA), intubation complication rates show a clear decrease after the implementation of guidelines for the management of the difficult airway (DA) in 1993. However, complications during extubation have not decreased. The complication rate during extubation and recovery has been reported as 14% and 5%. Among the claims that have appeared since 2000, 16 were related to extubation failure. Of these, 15 (94%) ended in death or permanent brain damage, and 8 occurred in patients with DA [5]. According to the NAP4 audit, a third of severe respiratory complications related to airway management happened during extubation or in the post anesthetic recovery care unit (PACU) [4]. The incidence of reintubation after a planned extubation, either in-operating rooms or in PACUs, is lower than that reported in ICUs (0,1-0,4% vs. 0,4-25%). Severe complications during extubation occurred in 13% of the cases and showed a 5% mortality. Reintubation cases in ICU are usually related to a longer duration of mechanical ventilation and an increase in mortality of up to 50%. The lack of an extubation strategy and inadequate risk factor assessments are associated with extubation failure, which contributes to an increased incidence of complications during extubation, both in ICU and PACU. Although more emphasis has been placed on the care that must be taken during this stage in recent years, extubation continues to be an overlooked process in the management of the difficult airway as compared with intubation. There are not many studies that can be used as a basis for the development of guidelines in the management of extubation. This lack of consensus makes the

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anesthetic management during extubation very variable. For instance, only 54% of anesthesiologists in the United Kingdom use a FiO2 of 100% prior to extubation. In January 2012, the Difficult Airway Society (DAS), in the absence of extubation management protocols, proposed an extubation guideline based mainly on experts' opinions and book chapters. These guides serve only for the management of extubation in adult patients, and they are not designed for the paediatric population or critical patients. In the absence of enough scientific evidence due to the lack of randomized studies, endorsement by the rest of societies is still necessary. However, these guidelines can be a helpful tool in the decision-making process during the assessment of a certain patient’s risk of extubation failure. The ASA Practice Guidelines for Management of the Difficult Airway (2013) states that an extubation plan is the logical extension of an intubation strategy. The anesthesiologist should, therefore, be prepared for extubation taking into account the characteristics of both the patient and the surgical procedure, as well as specific preferences and abilities [4]. It is impossible to guarantee successful and uncomplicated extubation. Consequently, it is advisable to consider all extubations as potentially complicated. Risk factors (depending on the patient and surgery) may be the cause of a higher percentage of complications during extubation. The identification of these enables us to stratify the risk and, thus, prepare a strategy in order to be able to anticipate complications that may arise. Careful extubation planning is required before intubation, since complications during tube removal are actually more frequent than during its insertion. DEFINITIONS Extubation Failure Although there is not a universally accepted definition for “extubation failure”, it can be defined as the inability to tolerate the removal of the endotracheal tube (ET) [6] requiring the reinstitution of non-invasive ventilatory support or reintubation. Benumof considers that extubation differs depending on whether it takes place in one of these two scenarios: PACU or ICU. He also intends to distinguish between extubation failure and weaning failure [5, 7].

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Extubation failure can happen to up to 72 hours after ET withdrawal. It is more common within the first two hours both in ICU and PACU, and rare after 24 hours [1, 8 - 10]. Early reintubation is uncommon after elective surgery and wellplanned extubation. Most common causes of failed extubation are: - Airway obstruction secondary to laryngospasm. - Bronchospasm. - Edema secondary to surgical manipulation or aggressive fluid management. - Bleeding that leads to airway compressing hematoma or intra-airway clots. - Poor secretion clearance. - Airway collapse secondary to tracheomalacia or residual effects of opioids or neuromuscular blocking agents. These causes of failed extubation are frequently described as extubation related complications or adverse during-extubation events. Weaning Failure It is the inability to sustain spontaneous breathing without ventilatory support. Treatment includes reintubation or, in selected patients, non-invasive mechanical ventilation (NIMV). Assessing the permeability of the airway, as well as its integrity and the presence of gag reflex, are critical steps. “At Risk” Extubation It is the situation in which the ability of the patient to maintain the airway patency and/or oxygenation after extubation is uncertain [3]. This definition was recently proposed in the frame of risk stratification during extubation, based on the assessment of the airway and general risk factors, such as the full stomach, cardiovascular instability and acid-base or temperature alterations. Difficult Extubation The concept of difficult extubation is complex, since many situations can be considered to contribute or result in a partial or complete extubation failure. There is little information regarding its incidence and morbidity. It could be defined as the inability to remove the ET. It is a rare situation that depends on mechanical factors, related to the patient, surgery or anesthesia [11]. E.g. subglottic stenosis, or severe airway edema are

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factors related to the patient. The wrong tube to tracheal fixing is a factor related to the surgery. ET malfunction or an incomplete cuff deflation are factors related to anesthesia. Risk Factors Risk factors that increase the rate of complications during extubation in the operating room can be related to the patient, associated pathology or derived from the surgery, either because it is focused on or around the airway, or due to surgery-related complications. Various pathologies are recognized by most authors as risk factors for difficulties during both intubation and extubation. According to NAP4, obesity (46%), COPD (34%) and Obstructive Sleep Apnea Syndrome (OSAS) (13%) are associated with problems during extubation. The DAS extubation guidelines consider as risk factors previous difficulties related to the airway (difficult airway expected, high risk of aspiration, obesity/OSAS) perioperative deterioration of the airway (anatomical distortion, edema or hemorrhage) and/or difficult access to the airway [4]. Risk Factors Associated with Extubation Failure in ICU are: age, prolonged mechanical ventilation (MV), anemia, disease severity, need for continuous IV sedation, need for the outside of ICU transfer and unplanned extubation. The most relevant risk factors are: -Obstructive Sleep Apnea Syndrome (OSAS): it increases the risk of gastroesophageal reflux, difficulty in ventilation and intubation and rapid desaturation. Post-extubation obstruction can occur in up to 7% of these patients. -Rheumatoid Arthritis: management can be difficult due to fibrosis and ankylosis by ligamentous destruction, limited mouth opening due alteration of the temporomandibular joint, limited cervical spine extension, narrow glottis, laryngeal deviation, micrognathia or crico-arytenoid arthritis. For all these characteristics they are considered high-risk extubation patients. It is recommended to extubate these patients when fully awake. -Tracheomalacia: airway obstruction due to tracheal cartilage loss. -Parkinson's Disease: these patients, having altered laryngopharynx movements, are at higher risk of airway obstruction and hypoxemia. They are more susceptible to laryngospasm (both spontaneous and induced after glottal stimulation) and the risk of gastric aspiration is higher. It is important to reintroduce the prescribed medication as soon as possible in these patients, in order to decrease the risk of complications during extubation. -Surgeries: thyroid, cervical, spinal and carotid surgeries can increase the risk of

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extubation complications. Other procedures in head and neck can be a cause of direct trouble in the airway due to edema, hematoma, nerve paralysis, reflexes abolition, altered lymphatic drainage vocal cords and tracheomalacia. Surgeries with greater risk of complications during extubation include: Cervical spine surgery, both performed by anterior and posterior approach. Several authors state that complications secondary to this surgery are mainly vocal cord paralysis and airway obstruction, especially due to pharyngeal edema, which is more frequent if the intervention duration exceeds 5 hours and when more than 3 vertebral bodies are approached, particularly when C2, C3 and C4 are involved. Carotid and thyroid surgery, especially because of the high incidence of hematoma (up to 12%) and cervical edema, can be caused by venous or lymphatic congestion. The dangerousness of cervical edema should not be overlooked. Voice changes should alert us, because clinical deterioration after stridor can be very rapid. Airway complications resulting from edema are not resolved in many cases after surgical wound opening, as retropharyngeal edema can cause an obstruction that may diminish the antero-posterior airway caliber. Furthermore, nerve injuries (glossopharyngeal and laryngeal nerve) have been described after carotid endarterectomy, causing alterations of the vocal cords and, consequently, of the airway. Maxillofacial surgery, posterior fossa surgery, stereotactic surgery, tracheal resection, palatoplasty and deep cervical infections (submandibular, sublingual or prevertebral abscesses) are also related to complications during extubation. ❍

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Causes of Failure of Extubation Several studies show that causes of reintubation after routine extubation are mainly related to respiratory problems, i.e., respiratory failure, hypoxemia, hypercapnia, airway obstruction (laryngospasm and bronchospasm) and insufficient reversal of neuromuscular blockade and opioid residual effect. Contrary to what might be expected, these last two causes (lack of reversal of neuromuscular blockade and the residual effect of narcotics) are the less frequent causes of extubation failure. Comparing groups of patients who required reintubation, most were patients with OSAS, obese patients with pneumonia, with ascites and those with an SRIS [7, 12]. Airway Obstruction is the most common cause of extubation failure both in the ICU and in the operating room. It can be due to laryngospasm, bronchospasm, laryngeal edema, pharyngeal muscle tone alteration causing collapse, cervical hematoma and vocal reflexes paralysis.

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Laryngospasm is an exaggerated glottic closure reflex caused by the stimulation of the superior laryngeal nerve. It is a common cause of obstruction, primarily in children, although it has been documented in 23.3% of adults. Although there are different stimuli that may lead to this complication (vagal stimulation, trigeminal, auditory, phrenic, sciatic, splanchnic stimulation, flexion or cervical extension, irritation, nasal, oral, pharyngeal or laryngeal) it is often triggered by irritation of the vocal cords by blood, vomit, oral secretions or surgical detritus, especially while on a superficial plane of anaesthesia. Clinical experience and scientific evidence suggest that intravenous anesthesia using propofol is associated with a lower incidence of complications related to exaggerated airway reflexes. Typically, laryngospasm causes signs of high airway obstruction and requires immediate treatment. If it is not rapidly addressed, it may cause post-obstructive pulmonary edema (also known as negative pressure pulmonary edema) and may even lead to cardiac arrest. The equivalent of laryngospasm at the level of the low airway is bronchospasm. Management should focus on prevention, patient extubation at a deep plane of anaesthesia or, alternatively, at a stage of full consciousness. Larson described an effective form of treatment consisting in firmly pressing so-called “laryngospasm notch”, which lies between the ascending ramus of the maxilla and the mastoid process [13] (Fig. 1).

Fig. (1). “The laryngospasm notch” (Original from: Larson PCJ: Laryngospasm–The best treatment. Anaesthesiology 1998; 89: 1293-1294). (bit.ly/2Lx64NM).

When vocal cords paralysis is caused by vagus or recurrent laryngeal nerve injury,

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the incompetence is bilateral and can cause severe airway obstruction, requiring immediate reintubation. It is a rare complication, most frequently seen after thyroid, cervical or thoracic surgery. Laryngeal edema is a major cause of post-extubation obstruction and may not become evident before extubation. It can be supraglottic, retroarytenoidal or subglottic. -Supraglottic Edema causes further displacement of the epiglottis, decreasing the size of the larynx and causing inspiratory obstruction. -Retroarytenoidal Edema hinders the mobilization of the cartilages, restricting cords abduction during inspiration. -Subglottic Edema occurs primarily in infants and children due to edema in the connective tissue that surrounds the cricoid cartilage. The patient position (prone or prolonged Trendelenburg), duration of surgery, fluid overload and anaphylaxis can contribute to airway edema. Laryngeal edema is presented as inspiratory stridor 30 to 60 minutes after extubation, although it may occur up to 6 hours later. Residual Neuromuscular Blockade alters protective airway reflexes. A TOF ratio of 0,7-0,9 is associated with pharyngeal function alteration and obstruction, increasing the risk of aspiration and attenuating the ventilatory response to hypoxia. Acute Pulmonary Edema, also called negative pressure pulmonary edema [14], occurs after severe airway obstruction due to laryngospasm, airway tumors or, more rarely, by vocal cords paralysis. It can also be caused by airway stimulation, especially in superficial anesthesia stages. Post-operative obstructive pulmonary edema incidence is around 1/1000, being most frequent in young men. Other causes of acute post-operative obstructive pulmonary edema include croup, epiglottitis and foreign body airway obstruction [15]. Hypoxemia is one of the major problems that can be found during or after extubation, and may be due to any of the previously mentioned causes. Bronchopulmonary Aspiration has an incidence of 1 in 2.000-3.000 general anesthesias. There are no evidence-based recommendations that reduce the risk of this complication during extubation. Partial or complete obstruction of the airway is associated with an inspiratory effort increase. This generates a significant negative intrathoracic pressure, which opens the esophagus, increasing the risk of

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regurgitation and, therefore, of aspiration. General Risk Factors should also be considered, since they can also complicate or delay extubation. These include: alteration of respiratory function, hemodynamic instability, neurological or neuromuscular conditions, hypo or hyperthermia, electrolyte or acid-base disturbances and coagulopathy. EXTUBATION STRATEGY The keys to proper management of the airway during extubation are good preparation and an extubation strategy. When anaesthetists plan an extubation strategy, the risk of extubation failure must be assessed, as well as the feasibility of an early reintubation. The main objective of extubation is to avoid reintubation. This objective is extremely important when facing a Difficult Airway (DA), in which reintubation can involve greater risk for the patient and is a challenge for the anesthesiologist. Anaesthetists must remember that extubation is an elective technique and, therefore, it must be a well-planned, controlled, gradual and reversible process, and its execution must ensure minimal disruption in the O2 delivery. The team (staff and logistics), monitoring and assistance should have the same quality as during the induction / intubation. Airway stimulation should be avoided, and there must be a plan that allows ventilation and reintubation with the least possible difficulties. In most hospitals, there is a great pressure for the anesthesiologist to perform quick extubation, and frequently the situation for extubation is less controlled than that in the intubation. Several factors, both organizational and human, must be considered before determining the decision to extubate. The patient will not be safe until he regains “control” of his airway; this is why during extubation, the patient is still vulnerable and at-risk [16]. According to NAP4, a lack of planning and insufficient anticipation of the problems that could emerge during extubation were present in 50% of reported cases of the failure of extubation. The DAS proposes three algorithms to manage extubation in its article on extubation handling: a standard one, another for ‘low risk’ extubation and the last one for ‘at risk’ extubation (Fig. 2).

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Each algorithm is divided into 4 steps: 1. 2. 3. 4.

Extubation planning. Preparation. Extubation. Postextubation care.

Fig. (2). DAS Extubation Guidelines: Basic algorithm. (Original from: www.das.uk.com/files/DASExtubation-Guidelines-Basic-Algorithm.pdf).

This guide is primarily based on the experience of authors and experts recommendations. An extubation plan strategy is recommended before anesthetic induction, using a phased approach in order to stratify the risk and identify the optimal management for each patient. This plan or extubation strategy should be revised before every extubation. Both step 1 (planning) and step 2 (preparation) make it possible to stratify the risk of extubation failure in order to be ready for step 3 (performing the actual extubation).

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Step 1: Plan General risk factors should be considered. Anaesthetists can assess the risk of extubation failure using questions such as the following: - Are there risk factors related to the airway? - Was the airway not difficult during induction? - Were there any changes in the airway? - Are there any general risk factors? Thereby when preparing an extubation strategy, anaesthetists will need to stratify patients according to assessed risk factors in order to classify them in one of the two large groups (low or high risk of extubation failure) and to act according to the corresponding algorithm (Figs. 3 and 4).

Fig. (3). DAS Extubation Guidelines: Low risk algorithm. (Original from: www.das.uk.com/files/DASExtubation-Guidelines-Lowrisk-algorithm.pdf).

Based on this classification, it can be said that low risk extubation includes routine, uncomplicated extubations, where the airway is normal or not complicated during the induction and where no changes occurred during the surgery.

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On the other hand, high-risk extubation will be that in which the reintubation, if needed, is not granted. That is, the anaesthetist has no security to establish a permeable and safe airway as soon as possible, either due to patient-related factors (OSAS, rheumatoid arthritis, Parkinson's disease, DA) or to alterations related to the surgery (endarterectomy, carotid, cervical, cervical contusion, etc.).

Fig. (4). DAS Extubation Guidelines: “At risk” algorithm. (Original from: www.das.uk.com/files/DASExtubation-Guidelines-Atrisk-algorithm.pdf).

Step 2: Prepare The preparation aims to optimize the airway and all the factors to ensure the best conditions and the success of the extubation. Final Evaluation and Optimization of Airway Related Factors: the airway should be reassessed at the end of surgery and prior to extubation, to determine the most appropriate reintubation plan. It is essential to know if mask ventilation is possible. Edema, bleeding, clots and foreign bodies can be measured by direct or indirect laryngoscopy.

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It is important to remember that the presence of an endotracheal tube can give a falsely optimistic of the larynx, and that edema can progress rapidly and become more evident after extubation. If the rescue plan includes subglottic access, neck accessibility must be confirmed. Step 3: Extubation Any extubation technique should ensure minimal interruption of oxygen administration. The following considerations are relevant for extubation both in low and high risk cases (Table 1): ●

-Increase the residual capacity of oxygen (pre-oxygenation): both anatomical and physiological perioperative changes described earlier can compromise the gaseous exchange. Therefore, pre-oxygenation prior to extubation is vital.

As during induction, it is suitable to increase the FiO2 above 0.9, and it is recommended to use 100% oxygen (although some studies show the increase of atelectasis, clinical relevance is still not certain). Lung recruitment before extubation has not shown benefit. ●

●

-Patient position: there is no evidence to recommend one position when extubating, although there is a tendency to favor reverse Trendelenburg or semiseated position, especially in the obese population. -Aspiration: oropharyngeal soft tissue can be injured if it sucks without sight. Ideally, a laryngoscope should be used in order to aspirate secretions, blood or detritus. Low airway aspiration using a bronchial catheter is advisable in some cases.

Several techniques are described as part of the extubation strategy. Among them: the leak test, the stridor detection test, the Bailey manoeuvre, the use of tube exchangers or guides and the extubation while the patient is under the effects of sedatives. Leak test consists of deflating the cuff in order to detect whether there is peritube leakage. It can be used to assess the subglottic caliber. Extubation is not secure in the absence of leakage around the cuff and, if there is clinical suspicion of airway edema, it is advisable to postpone extubation. On the other hand, many studies have shown that the presence of a leak does not ensure successful extubation.

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The post-extubation stridor detection test simply consists of listening to the neck with a stethoscope. This test is useful to detect early stridor, even before it becomes clinically apparent. Table 1. Sequence of extubation in patients at low risk. 1. 100% FiO2. 2. Vacuum if oropharyngeal secretions is performed under direct vision. 3. Prevent tube occlusion bite. 4. Ensure the correct position of the patient. 5. Antagonize the residual effect of muscle relaxants. 6. Set proper spontaneous ventilation. 7. Patient awake (open your eyes and obey orders). 8. Minimize movements of the head and neck. 9. Apply positive pressure, deflate the inflatable cuff and remove the tube. 10. Administering O2 to 100% and confirm the patency of the will and adequate ventilation. Continue to administer O2 by mask until complete recovery.

EXTUBATION WITH THE PATIENT ASLEEP It is an advanced technique and should be reserved for patients in whom the management of the airway is easy, and in those where the risk of aspiration is not increased. It reduces the incidence of cough and hemodynamic changes associated, with the disadvantage of an increase in the incidence of obstruction in the high airway. It is possible to reduce the risk of blockage of ETE by exchanging it through a laryngeal mask (LMA) before eduction (Bailey manoeuvre). None of these techniques should be carried out without adequate training and experience in their use, and if there is not a safe extubate scenario, extubation will be postponed to PACU or ICU or a tracheostomy will be performed. EXTUBATION AWAKE The awake patient extubation cases are usually safer, since patients recover the tone of the airway and their protective reflexes. An example of extubation at risk is the case of a patient operated on an aortic aneurysm with general risk factors such as the full stomach, acidosis or alkalosis, hypothermia and cardiovascular instability. Another example of extubation of risk is where awake intubation with a fiberoptic bronchoscope has been performed in a patient with DA.

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When there are risk factors, extubation will be performed in the same way as if they did not exist. However, in patients at risk, i.e., those with a risk of aspiration, obese or patients with DA, one or more of the following techniques may be beneficial. Exchange the Tube by a Laryngeal Mask (Bailey´s maneuver). This maneuver keeps the airway permeable and protected (Table 2). This technique shows superiority when compared to awake or asleep extubation and is used in cases where there is a risk of wound dehiscences due to hypertension caused by the endotracheal tube. It may also be beneficial in smokers, asthmatics and patients with a reactive airway. Table 2. Bailey´s maneuver. 1. Manage FiO2 100% 2. Avoid the stimulation of the airway: is essential good depth of anaesthesia or neuromuscular blockade. 3. Aspirate secretions. 4. Insert the LMA deflated behind the tube. 5. Make the position of the LMA. 6. Inflate the LMA. 7. Deflate the tube cuff and remove while maintaining positive pressure. 8. Continue with FiO2 100% 9. Avoid obstruction of the LMA by the bite. 10. Keep the patient in proper position. 11. Continue with extubation.

It is not appropriate in patients where reintubation may be difficult or if there is a risk of regurgitation. This technique requires practice and is essential to ensure an adequate anesthetic depth to prevent laryngospasm. Similar to Bailey´s Maneuver, techniques are as follows: 1. Remove the tube before the LMA, and then pick up secretions. 2. Insert an FBO through the LMA to confirm its correct position and observe the mobility of the vocal cords. This technique is very useful after thyroid or parathyroid surgery, and in situations in which the integrity of the airway may have been altered.

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EXTUBATION WITH TOTALTRACK® VIDEO LARYNGEAL MASK (VLM) Two-Phase extubation planning with TotalTrack® VLM is a viable and safe extubation strategy with continuous visualisation and uninterrupted ventilation, using VLM as SAD in Bailey´s manoeuvre [3]. This strategy allows a gradual control of awakening, seeing the vocal cords, allowing them to remove our device once the patient is ventilating correctly (Fig. 5).

Fig. (5). Two-Phase extubation planification with TotalTrack® VLM (A, B), and eduction and extubation as a SAD dispositive (C) [3].

EXTUBATION ASSISTED BY AN EXCHANGER This technique can be useful in patients where reintubation may be difficult after extubation. The device is inserted into the trachea through the tube prior to extubation. Exchangers can be used as guides for the endotracheal tube and pulmonary oxygenation. TRACHEOSTOMY PROCEDURE This technique is indicated when the permeability of the airway can be compromised at the end of the surgery due to airway problems that already existed or issues arising during surgery (bleeding, edema, extensive tumor, etc.) and / or if it is anticipated that the resolution of the problem may take as long as weeks or months. It must include the evaluation of the level of consciousness, respiratory rate, heart rate, blood pressure, peripheral saturation of oxygen, temperature and pain assessment. A Difficult Airway trolley must be available. The patient should stay under monitoring in the recovery room and capnography must be available. All extubations should be supervised by an anaesthesiologist and potentially

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dangerous extubation should be performed in the operating room. Those patients in whom there is a doubt about the risk of extubation failure should be transferred under the supervision of an anesthesiologist to the PACU or ICU. During the transfer, the necessary materials and experienced personnel must be available. The pulse oximeter is not a ventilation monitor and can give incorrect measurements in many circumstances; it should never be used as a single monitor. Warning signs can be divided into: - Early (of the airway): stridor, respiratory pattern, blockage and agitation. - Derivatives of surgery: debit by drainage perfusion in free flaps, airway bleeding, hematoma formation, airway inflammation. - Late: Mediastinitis, lesion of the airway. Mediastinitis may appear after difficult intubation and is characterized by pain (severe pain in the throat, deep cervical pain, dysphagia, pain swallowing), fever and crackling. Patients should be informed about the signs of mediastinitis so they can seek medical help if it occurs. An analysis of ASA close claims determines that most common injuries involve larynx after routine intubation and pharynx and esophagus after difficult intubation. A patient who is restless or complains of shortness of breath should never be ignored, even in the absence of other alarm signs. RESPIRATORY CARE IN PATIENTS WITH AIRWAY COMPROMISE Patients with airway commitment should be closely watched and high-flow humidified oxygen should be administered. It is desirable to monitor the ETCO2. Patients should keep fasting until laryngeal competence and full level of consciousness have been recovered. Factors that may prevent venous drainage should be avoided. Deep breaths and coughing should be encouraged in order to improve secretion clearance. In OSAS´s patients, a nasopharyngeal cannula can open the tract obstruction. If the patient is using CPAP at home, it should be available to be used in the resuscitation room.

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Although there are contradictory data regarding the use of glucocorticoids to prevent post-extubation stridor, they can be used prior to extubation. Glucocorticoids reduce airway swelling when this has been the result of direct injury (surgery, anesthesia, thermal, chemical) but they have not been effective in secondary edema due to venous compression (cervical hematoma). The evidence suggests that all steroids are just as effective at equivalent doses. They should be initiated as soon as possible in patients at high risk of airway inflammation or edema. A single dose prior to extubation is ineffective, so it is recommended to administer at least 3 doses [17]. Opioids such as alfentanil, fentanyl and morphine have been used to suppress the cough reflex. Currently, remifentanil and dexmedetomidine [18] are the drugs of choice. The presence of an endotracheal tube may trigger cough, agitation and hemodynamic alterations during the eduction. In some groups of patients (e.g., neurosurgical, maxillofacial, plastic and those with heart disease and stroke), cough is undesirable. The suppressive effect of cough and cardiovascular complication related to opioids are well known. The infusion of remifentanil or dexmedetomidine mitigate these undesirable effects, and they can be used to improve tube tolerance in patients who are awake and obey orders. Lidocaine has been used to reduce cough, and it can be used topically for intubation and IV prior to extubation. Other drugs that may also be useful to reduce respiratory and hemodynamic changes associated with extubation are calcium channel blockers, magnesium, clonidine, ketamine and β-adrenoceptors blockers [18]. If obstruction or stridor in the high airway is developed, nebulized adrenaline can be used. Helium may also be helpful but decreases the FiO2. Analgesia optimizes respiratory function. However, analgesia with sedative action should not be used or at least used at careful doses. Antiemetics may also be very important. DOCUMENTATION AND RECOMMENDATIONS - Clinical details and instructions for recovery and post-surgery care must be well documented. - Details of management, future recommendations and difficulties must also be well documented in the alerts section of a database. A copy should be sent to the family doctor and another patient, who must give a detailed explanation when it can retain that information. In addition, the patient must be warned about late symptoms of trauma in the airway and recommend to seek medical help.

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- Patients with Difficult Airways should be registered in a medical alert database. CONCLUSION - Intubation and extubation are two of the most important phases in the handling of the airway. Extubation can become a critical juncture, mainly when intubation has been difficult, so it is indispensable to be prepared. - The risk factors of extubation failure should be carefully rated and resolved or addressed in each case. CONSENT FOR PUBLICATION Not Applicable. CONFLICT OF INTEREST The authors confirm that the content of this chapter has no conflict of interest. ACKNOWLEDGEMENTS Declare none. REFERENCES [1]

Mort TC. Continuous airway access for the difficult extubation: the efficacy of the airway exchange catheter. Anesth Analg 2007; 105(5): 1357-62. [http://dx.doi.org/10.1213/01.ane.0000282826.68646.a1] [PMID: 17959966]

[2]

Asai T, Koga K, Vaughan RS. Respiratory complications associated with tracheal intubation and extubation. Br J Anaesth 1998; 80(6): 767-75. [http://dx.doi.org/10.1093/bja/80.6.767] [PMID: 9771306]

[3]

Hurtado EM, Merchante MS. Safe extubation with Totaltrack® VLM. Acad Anesthesiol Int 2016; 1(1): 3-5. [http://dx.doi.org/10.21276/aan.2016.1.1.2]

[4]

Cook TM, Woodall N, Frerk C. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 1: anaesthesia. Br J Anaesth 2011; 106(5): 617-31. [http://dx.doi.org/10.1093/bja/aer058] [PMID: 21447488]

[5]

Metzner J, Posner KL, Lam MS, Domino KB. Closed claims’ analysis. Best Pract Res Clin Anaesthesiol 2011; 25(2): 263-76. [http://dx.doi.org/10.1016/j.bpa.2011.02.007] [PMID: 21550550]

[6]

Epstein SK. Decision to extubate. Intensive Care Med 2002; 28(5): 535-46. [http://dx.doi.org/10.1007/s00134-002-1268-8] [PMID: 12029399]

[7]

Artime C A, Hagberg C A. Tracheal extubation. Respiratory Care 2014; 59(61): 991-1002– discussion 1002–5. [http://dx.doi.org/10.4187/respcare.02926]

[8]

Nwakanma CC, Wright BJ. Extubation in the Emergency Department and Resuscitative Unit Setting. Emerg Med Clin North Am 2019; 37(3): 557-68. [http://dx.doi.org/10.1016/j.emc.2019.03.004] [PMID: 31262421]

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[9]

Faris K, Zayaruzny M, Spanakis S. Extubation of the difficult airway. J Intensive Care Med 2011; 26(4): 261-6. [http://dx.doi.org/10.1177/0885066610389551] [PMID: 21887863]

[10]

Ramachandran SK, Nafiu OO, Ghaferi A, Tremper KK, Shanks A, Kheterpal S. Independent predictors and outcomes of unanticipated early postoperative tracheal intubation after nonemergent, noncardiac surgery. Anesthesiology 2011; 115(1): 44-53. [http://dx.doi.org/10.1097/ALN.0b013e31821cf6de] [PMID: 21552116]

[11]

Nag D S, Samaddar D P. Inappropriate fixation of an endotracheal tube causing cuff malfunction resulting in difficult extubation. Brazilian Journal of Anesthesiology 2016; 66(5)536 [http://dx.doi.org/10.1016/j.bjane.2013.04.009]

[12]

Ting PC, Chou AH, Yang MW, Ho AC, Chang CJ, Chang SC. Postoperative reintubation after planned extubation: a review of 137,866 general anesthetics from 2005 to 2007 in a Medical Center of Taiwan. Acta Anaesthesiol Taiwan 2010; 48(4): 167-71. [http://dx.doi.org/10.1016/j.aat.2010.12.003] [PMID: 21195986]

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Larson CP Jr. Laryngospasm-the best treatment. Anesthesiology 1998; 89(5): 1293-4. [http://dx.doi.org/10.1097/00000542-199811000-00056] [PMID: 9822036]

[14]

Krodel DJ, Bittner EA, Abdulnour R, Brown R, Eikermann M. Case scenario: Acute postoperative negative pressure pulmonary edema. Anesthesiology 2010; 113(1): 200-7. [http://dx.doi.org/10.1097/ALN.0b013e3181e32e68] [PMID: 20526178]

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Udeshi A, Cantie SM, Pierre E. Postobstructive pulmonary edema. J Crit Care 2010; 25(3): 508.e1-5. [http://dx.doi.org/10.1016/j.jcrc.2009.12.014] [PMID: 20413250]

[16]

Heidegger T. Extubation of the difficult airway-an important but neglected topic. Anaesthesia 2012; 67(3): 213-5. [http://dx.doi.org/10.1111/j.1365-2044.2011.07043.x] [PMID: 22321073]

[17]

Robert C. Hyzy, Scott Manaker, Geraldine Finlay extubation management. Up to date 2016; (Aug): 16.

[18]

Shruthi AH, Nethra SS, Sudheesh K, Devika Rani D, Raghavendra Rao RS. Effect of dexmedetomidine on hemodynamic parameters during extubation. A prospective randomized double blind study. Middle East J Anaesthesiol 2016; 23(4): 457-63. [PMID: 27382816]

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CHAPTER 22

An Update on Airway Management Education María Luisa Mariscal Flores1,*, Alfonso Anduenza Artal2, Sonia Martín Ventura1, Claudia Palacios Muñoz1 and Rocío Castellanos González1 Department of Anesthesiology and Critical Care Medicine, Hospital Universitario de Getafe, Madrid, Spain 2 Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Fundación Alcorcón, Madrid, Spain 1

Abstract: Until recently, the anaesthesiology and resuscitation resident training in difficult airway (DA) consisted solely of learning the techniques to maintain a patent airway, ventilation with face mask and direct laryngoscopy. In addition, it was believed that their acquisition was possible only with the repetition of such techniques during training, assuming that enough cases were exposed to meet this objective. There are several reasons that make it necessary to review this training system. such as the known data of avoidable morbidity related to DA, the development of a large number of new techniques for the management of DA in the last decade, the lower exposure of the resident to tracheal intubation, derived from the great thrust of regional anaesthesia, use of supraglottic elements or greater dedication to rotations outside the operating room. Besides, there have been advances in research on airway learning that deserve attention.

Keywords: Airway learning, Airway management, Direct laryngoscopy, Education, Morbidity, Mortality, Safe, Simulation, Supraglottic, Training, videolaryngoscopy. INTRODUCTION One of the most important aspects of the training of an anesthesiologist is appropriate airway management (AM). One of the main challenges in this field is that the incidence of difficult airway (DA) is low, but the lack of experience may turn orotracheal intubation into a catastrophic event.

Corresponding author María Luisa Mariscal Flores: Department of Anesthesiology and Intensive Care, Hospital Universitario de Getafe, Madrid, Spain; Tel/fax: 0034 916 83 93 60; E-mail: [email protected]

*

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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During training in anesthesiology, medical residents pretend to be able to manage their VSHFLDOW\, including airway (Fig. 1). The definition used byliterature on professional competence is “judicious and regular use of communication, knowledge, technical skills, clinical reasoning, emotions, values and reflexion in daily practice for the benefit of the individuals and the community we attend” [1]. Training in AM requires a combination of knowledge, technical abilities, decision making, communication skills and leadership [2].

Fig. (1). Difficult Airway training in anesthesia residency.

JUSTIFICATION Published clinical guidelines for Difficult Airway (DA) management recommend the development of training programs based on the use of algorithms [3 - 5]. However, the responsible organisms for training and accreditation in anesthesiology have not defined a specific program on this subject. The Accreditation Council for Graduate Medical Education (ACGME) in the U.S. recommends the development of programs that ensure a significant experience in special techniques of airway management, including fibrobronchoscopy (FOB) and laryngeal mask (LMA). The European Board of Anaesthesia, Reanimation and Intensive Care [6] suggests a minimum number of techniques to be carried out such as spinal anaesthesia, epidural anaesthesia and central venous and arterial

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catheterization, but does not mention basic or advanced airway techniques [7]. This means that each hospital must determine the content and form of training in DA. According to the available data from published studies and surveys, few centres have developed a structured training program in DA [8]. Several reasons could explain this fact: logistical problems of teaching in the operating room, always conditioned by workload and need for agility; ethical reasons on the possible risks of these techniques for the patient; lack of safety culture, and lack of competent trainers in new development devices. The Fourth National Audit Project (NAP4) of the Royal College of Anaesthetist and the Difficult Airway Society (DAS), is one of the most interesting publication in the recent years [9], in which 184 cases of patients with severe morbidity and mortality due to AM complications are described. It was reviewed by a group of experts to find the related factors: A poor judgment and inadequate education and training in AM were described as the second and third causes of these complications. For all the above- mentioned, discussion it is necessary to establish systematized training programs in AM in every hospital and in different airway societies. DIFFERENT FORMS OF AIRWAY MANAGEMENT TEACHING The theorical knowledge that must be obtained by an anaesthesia medical resident on the AM should be defined. Several published training programs include [10]: ● ● ● ● ● ●

●

Airway anatomy Basic management on airway. Prediction of difficult airway Prediction of difficult ventilation Difficult Airway algorithms. Detailed description of the equipment and techniques planned to be used (Including preparation for awake intubation and invasive techniques). Complications related to the management of the airway.

Different ways have been described for theoretical training based on the points mentioned above: selection of bibliography for medical residents and discussion about it, theoretical sessions, interactive multimedia material and videos, etc. [7]. Before the first contact with the airway patient in clinical practice by the resident, the desirability of certain essential theoretical training has been discussed. At a minimum, it should include information of the airway anatomy and a detailed

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description of techniques to be used. The residents must learn both technical and non-technical skills. Technical Skills The ACGME (Accreditation Council Medical for Graduate) and The American Board of Anaesthesiology, in the section on technical skills in the management of airway included in the Milestone Project [11], specify that during the anaesthesiologists training, “they must perform” Basic and Advanced management of the airway. Basic ● ● ● ●

Face mask ventilation. Direct laryngoscopy. Supraglottic airway device. Videolaryngoscopy (direct and indirect laryngoscopy).

Advanced ● ● ● ●

Awake intubation. Fiberoptic intubation. Lung isolation. Cricothyrotomy.

Different published training programs and articles on teaching airway management indicate the need to learn techniques, the utility of which has been demonstrated in clinical practice. It is accepted, that nowadays, the training and learning of all the existing techniques are impossible. It seems clear that residents should receive training on a selected group of techniques which allow them to carry out every step of DA algorithms (nuclear, essential skills or “minimum competition kit”). Therefore, based on the latest ASA algorithm, residents should choose some techniques from the list below to be used in their sequence of steps. ● ●

●

●

Expected difficult airway: awake patient intubation. Alternatives to failed direct laryngoscopy: videolaryngoscopy/intubation through supraglottic devices / fiberoptic intubation/bright stylet / blind oral or nasal intubation. Alternatives to face mask ventilation: supraglottic devices (laryngeal mask/laryngeal tube). Emergent invasive access: surgical or percutaneous approach/retrograde intubation.

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The training in DA is not standardized in official accreditation and training (Royal College of anaesthetists ACGME) organizations. They recommend the development of programs, but relegated to different hospital departments. According to survey studies, more hospitals are increasingly organizing a systematic training, including a specific rotation. This is justified by the complexity of the techniques to teach, the limited operating room time and the variability among different professionals. A specific rotation would ensure at least exposure to a minimum number of cases, techniques, and expert guidance. Although residents can easily use basic routine use techniques, it is safer than using more advanced and complex techniques. Before recommending a specific rotation, several aspects should be made clear [11]: ●

●

●

●

●

Specific techniques for the rotation: it depends on each hospital which devices are available and which one is defined as basic or advanced. Those who have related experience start by selecting DA trolley material for later transmission to the resident. Duration of the rotation: between two weeks and two months, depending on the proposed objectives and the number of cases that can be seen in a week. Duration of rotation: each one has its advantages and disadvantages. In general, an early start has been considered more appropriate an early start, believing that young doctors can perfectly acquire these skills and have more time to improve them. There is no evidence to learn these techniques in a staggered way. Appointment of the instructors: the importance of choosing between people who not only have experience, but also motivation to pass on their knowledge has been highlighted. Some articles maintain the convenience of a single responsible instructor at the beginning to ensure the continuity of education. It could be enriching in a later stage. Methodology of rotation: the convenience of the following points has been discussed in the published literature: Previous delivery of literature, videos or multimedia information and a detailed description of the basis of the design, insertion techniques, correct placement confirmation procedures and potential complications of the different devices included in the rotation. Use of artificial models: there seems to be enough information to defend previous training on mannequins or non-anatomical models of manual techniques in the early stages of learning, and as a consequence, for real cases to succeed, a higher success rate, lower esophageal intubations, etc. In addition, other advantages like learning in a more relaxed environment and leaving residents to work on their own have been described. For this purpose, ❍

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there are different equipment: models, mannequins, animals, corpses and maybe the only possibility to carry out invasive techniques. Use of TV monitors: faster learning has been described where it has been used. In addition, it provides greater protection to the patient, and allows an analysis of its utility by recording the technique. Definition of a minimum number of procedures: some articles have tried to identify the number of cases needed to learn certain techniques with a high rate of success. In general, the minimum number of cases to be carried out is defined by rotations. There is not an official number of cases required during residency (the ACGME only indicates that the resident must acquire "a significant experience"). Assistance to intubations in patients with difficult airway predictors: an advance notice of surgical programming of these patients is required. A case evaluation and an action plan establishment are convenient to be carried out by the resident. Protection of the patient [12]: both the studies on learning curves and those that describe the specific rotations, protect patients by limiting the number of attempts or execution time of the technique. Good judgement stimulation: DA training is not only having good skills with a set of devices. In order to describe the indications, contraindications, benefits or potential dangers of the techniques, the discussion and reflection of all the seen cases and the planning of other possible variants and hypothetical incidents ("what-if" scenarios) have been suggested. The use of algorithms must be taken as a guide in decision making.

Non-Technical Skills The importance of integrating knowledge and skills in organized plans that require the capacity of making decisions, communication, teamwork and leadership is increasingly recognized in anaesthesia in general, and in the management of DA especially [13]. It has been proposed that a proper learning should include these abilities (non-technical skills), which has been called “an integral management of the airway. It is difficult to practice required skills in uncommon crisis scenarios in real patients. With this purpose, HD simulators have been designed [14] to train regarding the global task by replicating a real clinic scenario and using both technical and non-technical skills. Non-technical skills include: ● ● ●

Ask the right questions. Find relevant data. Devising plans of action (strategy, ability to follow an algorithm).

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Communicate plans to the rest of the team. Resolve conflicts. Make decisions. Command from the rest of the team.

This methodology has been adopted by simulation centres, although it is difficult to develop and implement [15]. Some authors defend the well-established efficacy of simulators, but its effect in reducing the incidence of bad forecasts is more controversial. Simulation is an ideal method for the reproduction of clinical situations and it is helpful for the evaluation of different strategies, decision-making and monitoring of algorithms [16]. The effectiveness of medical simulation education is well established, but its effects in reducing the incidence of adverse events are not clear. It is easy to check the effect of the theoretical reading or the analysis of pretest and post-test knowledge. It is not that easy to test the effect of simulation in the care of patients in critical situations like the DA. However, there is scientific evidence that proves that the simulation and training in clinical situations improve patient care [17]. VIRTUAL REALITY SIMULATION AND THE PROGRAMS THAT ALREADY EXIST Simulation in anaesthesia has revolutionized the teaching method because it allows an interactive and immersive activity recreating a clinical experience without exposing patients to risks of failure of proper airway management. The cost of simulation is the main concern in program implementation, especially in developing countries. Simulation-based training compared to conventional learning has more advantages, especially in ethical aspects. Almost half of the residency programs in USA have incorporated simulation-based training. The next step will be the virtual reality: students will experience clinical scenarios through software specially designed for their education. In this sense, there are already several studies which demonstrate that virtual airway simulation improves the dexterity of beginners in performing upper airway endoscopy [18].

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A MODEL OF FORMATION IN DIFFICULT AIRWAY MANAGEMENT IN THE ANAESTHESIA SERVICE OF THE UNIVERSITY HOSPITAL OF GETAFE (MADRID, SPAIN) A DA training proposal for residents of Anaesthesiology and Resuscitation is presented below, which has been in force in the University Hospital of Getafe (UHG) since 2004. The main goal of the program is that the resident in anaesthesiology and resuscitation acquire the necessary skills to carry out the highlights of DA algorithms of the 2013 ASA and the DAS 2015. Firstly, techniques considered as essential for the implementation of the algorithms have been classified as basic and advanced techniques: ●

●

Basic Techniques: their learning begins from the first day and is reinforced during the whole period of UHVLGHQF\. Every consultant of the team is capable of teaching them. Advanced Techniques: resident begins to learn them at the end of the second year of UHVLGHQF\. This part of the training is divided into several phases [9]: Firstly, updated bibliographic material to study and further discuss. Secondly, there is a mixed course (online and face-to-face) in difficult airway divided into three modules: two modules are 100% online, with a total of 80 hours each, and a third one (online- attendance) that includes a full day of physical presence in the Centre of simulation IDEhA (Hospital Universitario Fundación Alcorcón, Madrid) and an online module. To keep the groups of practices small, students of module III are separated into two groups (Figs. 2 and 3). ❍

❍

Each online module is developed by the student in two months, receiving 13-14 chapters per module, which could be downloaded in order to make the study easier. The differential feature of this course is the interactivity between the student and the tutor (14 tutors + guest teachers). There are various purposes to solve clinical cases, to expose doubts, to talk with other students. Also, each part has a web link to AnestesiaR which allows access to various entries related to the topic that the student is reading. Students are evaluated throughout the entire course for their involvement in the resolution of several issues raised in each part and the solution of clinical cases and finally, they carry out a self-evaluation.

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The course has a video library of procedures and devices, an airway dictionary with which the student can consult in case of doubt of any term exposed in the text and a consultation chat in real time. Finally, a specific rotation is performed in DA and the previously learned techniques are carried out in real patients. The DA rotation has a duration of 2 months and it takes places in the otorhinolaryngology operating room (Fig. 4). A single experienced teacher participates during this period. To ensure the presence of the instructor during every session, the participation of other anaesthesiologists who collaborate in the training of specific skills is required. During this rotation, a target of a minimum number of exhibitions for different techniques depending on their complexity is set. Whenever possible, video systems are used to provide both the resident and the instructor a joint vision.

Figs. (2 and 3). Difficult Airway Course CS-IDEhA. On-site module.

During this specific time, the training is complemented with the discussion of practical cases derived from possible variants of daily life situations in the operating room. Besides this, practical information on cleaning, sterilization and care of different devices, raising awareness about its fragility and cost is provided. At the end of the rotation, the resident must describe the activity carried out and indicate the number of the different techniques performed in order to compare with the indicated main objectives. In addition, progression is daily evaluated in clinical situations. This information is then provided to the tutor.

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Fig. (4). Rotation in DA in ENT operating room.

Once the rotation is over, residents are encouraged to complete their training by using the different devices together with experienced anaesthesiologists in each technique. EVALUATION AND MONITORING The main objective of the evaluation is to detect deficiencies and solve them. The evaluation of theoretical knowledge and how to apply it to real clinical situations is recommended. For this purpose, the use of interviews, written tests, assessment during routine anaesthesia, use of simulators, etc. have been suggested. For the monitoring of the acquired skills, it is recommended that the resident should register the number of cases carried out with each technique. This allows to identify if, at least, the target of a minimum number of cases is achieved. If a particular resident does not reach this target, it can be valued to extend the length of the rotation. On the other hand, if this happens frequently, it means that the duration or the targets are not realistic. It has been shown that there may be significant variability among students in the

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acquisition of different skills. For this reason, some authors proposed to evaluate the achieved competencies more than the number of cases carried out. Different tools for this purpose have been designed: CuSum curves, curves of accumulated success, systematic evaluation forms, etc. When one has the learning curves of several residents, then specific students can be compared with the media. CONCLUSION ●

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Over the past decade, a lot of materials on training methods in DA management have been published, indicating the official establishment of a specific rotation during anaesthesiology residency. It is considered that such responsibility must be assumed by every hospital with educational accreditation in speciality, rather than delegated exclusively in external courses. In the absence of recommendations by the competent trainers, our proposal may be considered useful for those services which are pending the development of a training plan on DA during the residency in anaesthesiology and resuscitation.

CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that this chapter’s content has no conflict of interest. ACKNOWLEDGEMENTS Declare none. REFERENCES [1]

Epstein RM, Hundert EM. Defining and assessing professional competence. JAMA 2002; 287(2): 226-35. [http://dx.doi.org/10.1001/jama.287.2.226] [PMID: 11779266]

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Baker PA, Weller JM, Greenland KB, Riley RH, Merry AF. Education in airway management. Anaesthesia 2011; 66 (Suppl. 2): 101-11. [http://dx.doi.org/10.1111/j.1365-2044.2011.06939.x] [PMID: 22074084]

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Apfelbaum JL, Hagberg CA, Caplan RA, et al. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2013; 118(2): 251-70. [http://dx.doi.org/10.1097/ALN.0b013e31827773b2] [PMID: 23364566]

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Guidelines to the practice of anesthesia. Revised Edition 2015 Canadian Journal of Anesthesia Volume 62, N°1.

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Frerk C, Mitchell VS, McNarry AF, et al. Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults. Br J Anaesth 2015; 115(6): 827-48. [http://dx.doi.org/10.1093/bja/aev371] [PMID: 26556848]

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Programa de formación en Anestesiología, Dolor y Cuidados Críticos (Syllabus to the postgraduate training program. From the standing Committee on education and training of the section and board of anaesthesiology).

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Paul A. Baker and Robert Tino Greif. Airway Management Education.Airway Manegement. 4. Eselvier 2017; pp. 891-904.

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Grande B, Kolbe M, Biro P. Difficult airway management and training: Simulation, communication and feedback. Current Opinion in anesthesiology 2017; 30: 1-5. [http://dx.doi.org/10.1097/ACO.0000000000000523]

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Cook TM, Woodall N, Frerk C, Fourth R, Mahajan R, et al. Fourth National Audit Project. Major complication of airway management in the UK: results of the Fourth National Audit Proyect of the Royal College of Anaesthetists and the Difficult Airway Society. Br J Anaesth. 2011; 106: pp. (5)61731.

[10]

Mariscal Flores M L, Pindado Martínez ML, Anduenza Artal A, Rey Tabasco F. Docencia en vía aérea difícil durante la residencia de anestesiología. María Luisa Mariscal Flores y Eugenio D. Martínez Hurtado. Manual de manejo de la vía aérea difícil. AnestesiaRorg. 3 Edición. 2017; pp. 459-67.

[11]

ACGME Program Requirements for Graduate Medical Education in Anesthesiology. ACGME approved focused revision: June 10, 2018; effective July 1, 2018 en web: bitly/2TbTJBn

[12]

Ward PA, Irwin MG. Mans vs. manikin revisited-the ethical boundaries of simulating difficult airways in patients. Anaesthesia 2016; 71: 1391-407. [http://dx.doi.org/10.1111/anae.13526]

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Myatra SN, Kalkundre RS, Divatia JV, et al. Optimizing education in difficult airway management: meeting the challenge. Curr Opin Anaesthesiol 2017; 30(6): 748-54.

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Lindkaer Jensen NH, Cook TM, Kelly FE. A national survey of practical airway training in UK anaesthetic departments. Time for a national policy? Anaesthesia 2016; 71(11): 1273-9. [http://dx.doi.org/10.1111/anae.13567] [PMID: 27679501]

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Hubert V, Duwat A, Deransy R, Mahjoub Y, Dupont H. Effect of simulation training on compliance with difficult airway management algorithms, technical ability, and skills retention for emergency cricothyrotomy. Anesthesiology 2014; 120(4): 999-1008. [http://dx.doi.org/10.1097/ALN.0000000000000138] [PMID: 24434303]

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Zonic L, Savoldelli GL. Evidence base in airway management training. Trend in Anaesthesia and Critical Care 2015; 5: 36-41. [http://dx.doi.org/10.1016/j.tacc.2014.12.002]

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Pedersen TH, Gysin J, Wegmann A, et al. A randomised, controlled trial evaluating a low cost, 3Dprinted bronchoscopy simulator. Anaesthesia 2017; 72(8): 1005-9. [http://dx.doi.org/10.1111/anae.13951] [PMID: 28603907]

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Komasawa N, Berg BW. Simulation-based airway management training for anesthesiologists - a brief review of its essential role in skills training for clinical competency. J Educ Perioper Med 2017; 19(4): E612. [PMID: 29766036]

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CHAPTER 23

An Update on Airway Management Registry and Organization Eugenio Daniel Martinez-Hurtado1,*, Miriam Sanchez-Merchante2, Pablo Renedo Corcóstegui3, Nekari de Luis Cabezón4 and Alicia Ruiz Escobar1 Department of Anaesthesiology and Intensive Care, University Hospital Infanta Leonor, Madrid, Spain 2 Department of Anesthesiology and Critical Care Medicine, Hospital Universitario Fundación Alcorcón, Madrid, Spain 3 Department of Anesthesiology and Critical Care Medicine, OSI Alto Deba, Mondragón, Guipúzcoa, Spain 4 Department of Anesthesiology and Critical Care Medicine, Hospital Universitario de Basurto, Bizkaia, Spain 1

Abstract: After an unexpected difficult intubation, management, documentation and sharing of relevant clinical information in the perioperative period may be useful to enhance the safety of the patient. The inclusion of these patients in a computerized hospital database, together with the creation of a visible information sheet, was proposed in 1992. Digital coded recognition, distribution and access to the digital data of the patient by different providers of health, and the registration of the patient in a medical alert base with a 24-hour access were also proposed as procedures to reduce the anesthetic morbidity and mortality related to the unexpected difficult intubation.

Keywords: BIG DATA, Database, Digital, Documentation, Information, Interhospitalary, Interoperability, Legislation, Security, Semi-structured data, Structured data, Unstructured data. INTRODUCTION One of the fundamental responsibilities of the anesthesiologist is airway control, which aims to establish a patent airway and ensure adequate oxygenation and ventilation. This is the cornerstone of anesthetic practice. Documentation and dissemination of critical information, including entry of patient data into an in-hospital computerized Difficult Airway/Intubation RegCorresponding author Eugenio Daniel Martinez-Hurtado: Department of Anaesthesiology and Intensive Care, University Hospital Infanta Leonor, Madrid, Spain; Tel/Fax: 0034 911 91 80 00; E-mail: [email protected]

*

Eugenio Daniel Martinez-Hurtado & María Luisa Mariscal Flores (Eds.) All rights reserved-© 2020 Bentham Science Publishers

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istry, summary reports distributed to health care providers and enrolment of the patient in the Medic Alert Foundation International's category difficult airway/intubation were suggested in 1992 [1]. The American Society of Anesthesiology (ASA) published the first difficult airway management algorithm [2] at the time when 28% of anesthesia-related deaths were caused by either the impossibility to guarantee ventilation with a facial mask or unsuccessful intubation. Recommendations derived from this document included a range of possibilities such as an information card, a bracelet or a specific mention in the medical record [3, 4]. The need for a specific airway management record was further explored by the Canadian Society of Airway Management in 2013 [5]. Their proposal recommended that a record ought to be filled including appropriate documentation after each airway intervention, difficult or not (strong recommendation, evidence level C). They proposed that within the record there should be specific mention of ease of ventilation with a face mask or supraglottic airway device (SAD), type of device used to perform tracheal intubation, obtained vision and the number of attempts. According to the Helsinki Declaration on the safety of patients in anaesthesiology, anesthesiologists share responsibility for the quality and safety of patient care in anesthesia, intensive care, emergency medicine and pain medicine, including all the peri-operative process, as well as in many other situations in which patients can be vulnerable. Anesthesiology is therefore, a medical specialty in which it is necessary to take responsibility for achieving these objectives, which, in turn greatly improves patient safety [6]. The above discussion may be summarized by the following two points: ●

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All the institutions that provide DQHVWKHVLD care to patients must collect all the data required to be able to produce an annual report on patient's morbidity and mortality. All the institutions that provide anesthesia care to patients must participate in audits or contribute to specific National Safe Practices Audits and critical communications systems. Adequate resources must be provided to achieve this.

The Difficul Airway Society of United Kingdom (DAS) guidelines 2015 highlight that the difficulties encountered in airway control during intraoperative management, as well as the implications that this may generate for postoperative care, should be discussed at the end of the procedure [7, 8]. This should be done not only through verbal information, but must also include a description of the airway management plan and clear documentation of the patient's medical history. The latter is particularly relevant, as the patient undergoes a follow-up by the

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anesthesia service to confirm and communicate possible complications that appear in the airway in the postoperative period. CLOSE CLAIMS PROJECT AND THE SAFETY OF PATIENTS In response to the rapid increase in the insurance premiums of professional responsibility during the 1980's, ASA developed the “Closed Claims Project” in 1984 to improve patient safety and prevent anesthetic injuries [9]. The database started in 1985, and currently contains over 8,954 claims [10], of which 581 are related to airway management. “Closed Claims Project” database analysis shows that the development of any airway emergency increases the likelihood of death or brain damage by 15 times [2]. For this reason, the ASA published the first practice guidelines for management of the difficult airway in 1993, the objective of which was to “facilitate the control of difficult airway and reduce the likelihood of adverse outcomes” [10]. Due to these guidelines, the proportion of claims attributable to airway complications has significantly dropped in the last three decades; nevertheless, airway complications are still the second most frequent cause of legal proceedings, only just surpassed by those related to regional blocks [10]. The 2011 NAP4 project [8] audited the major complications of airway management in the United Kingdom, and estimated that they occurred in up to a total of 46 cases per million of general anesthesias (95% CI 38-54), which was equivalent to1 in every 22,000 anesthesias (95% CI 1 each 26-18,000), with a rate of mortality or irreversible brain damage of 5.6 million of general anesthesias (IC 9 5% 2, 8-8, 3), 1 in every 180,000 (95% CI 1 each 352-120,000). The complications related to airway management are not limited exclusively to situations in which the primary plan is tracheal intubation, and 25% of anesthetic incidents reported to NAP4 began with the intention of managing the airway using an SAD. The percentages differ very little depending on the device used, either with a face mask, supraglottic airway device, or endotracheal tube. Although these figures can continue to make us believe that the incidence of death or irreversible brain damage attributable to the airway management during general anesthesia is low, the statistical analysis of the distribution of collection of cases suggests that the percentage of collected incidents would not exceed 25% of those that were estimated to truly occur. In other words, as up to 75% of events were not reported, the results could be up to 4 times more significant.

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While the rate of complications can be considered low, and airway management was considered good in 19% of the cases studied, a committee of experts considered that the management of airway was poor or very poor in 4 out of every 5 cases, and the review of the airway management in the affected cases suggested that there was a significant room for improvement in applied techniques. What should be known about patient's airway? Analysing the data provided by 570 anesthesiologists and nurses certified in the United States in 2013, the current prevalence of difficult laryngoscopy would be estimated at 10%, while data on difficult airway was not provided in approximately 4% of the cases [11]. This data is consistent with the previous evidence by Shiga in 2005 following their meta-analysis of more than 50,000 patients [12]. The NAP4 detected an incidence of difficult intubation between 1.15-3% (8% in the general population), although the impossibility of intubation was rare (0,13-0, 3%), due to the fact that modern technology and new devices have improved ability to manage the airway [8]. In 2008, through the data collected from 56 participating countries (out of 192 Member countries) the World Health Organization (WHO) estimated 234,2 million major surgical procedures per year (95% CI 187,2-281,2) [13]. In 2012, with the data provided from 194 countries, it estimated that this amounted to 312,9 million more surgical procedures per year (95% CI 266,2-359,5) [14]. Hence, it can be extrapolated from 2012 data that if 3% of unforeseen difficult airway (DA) are assumed [15], more than 9 million possible unforeseen DA a year can be found. However, although the history of difficult intubation has been recognized as one of the predictive factors of intubation difficulty, the fact that the history of difficult intubation or the failure of intubation had not been recorded does not lead to a failed direct laryngoscopy [16]. DOCUMENTATION OF CRITICAL INFORMATION ASA recognises that the existing literature is insufficient to demonstrate the benefit of disseminating information after an event of DA [3, 4]. However, their guidelines strongly recommend that informing the patient is a “must” and that the systems of notification, such as a letter or a report to attach to the medical record, communication with the primary care physician, alert type bracelet or similar systems “may” be advisable.

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DAS has developed algorithms only for the management of unexpected difficulty [6, 17], but instructions with the recommended action plan in the event of difficulty in airway management are available on their website [18]. In them, they indicate the need to record the event in the anesthetic chart and clinical history, offering a verbal explanation to the patient and providing a written report with a copy submitted to the primary care and to the department of anesthesiology. As a means to standardise the above, the DAS has initiated a pilot project for the development of a database of difficult airway in the United Kingdom (https://www.das.uk.com/dad). A DA alert card for patients has also been designed (Fig. 1).

Fig. (1). DAS Difficult Airway CARD.

Finally, the DAS recommended that a model or proforma report be provided so that the essential information is accurately recorded and the appropriate steps are taken [18]. The Italian Society of Anesthesiology, Analgesia, Resuscitation and Intensive Therapy (SIAARTI) in its 2005 published DA guidelines [19] considered it “mandatory” for any service of anesthesiology to produce a standard operating plan for the provision of care during DA performance. This should include written information on successful management and written notification to the patient. The Austrian airway management working group [20] also recommended that a verbal explanation and a written report be given to the patient. They especially advise on the development of a database with the most relevant up to date information to be available upon both in-house or external requests. Denmark has implemented a national early warning system in DA consisting of an identification card that is delivered to the patient for safe-keeping, with the

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most important data of the event [21]. A notification by various means to ensure easy access to information to the history of DA has also been recommended by Canadian [22] and French [23] Societies. The communication of success and failure of the airway management techniques is composed of two parts: 1. Documentation at the time of the event (pre-anaesthesia, anaesthesia, postanaesthesia) by related specialists with the episode. 2. Broadcasting that information to other specialists for further / future episodes. DATABASES, RECORDS, AND CLINICAL PRACTICES There are currently various mechanisms to record the data and communicate a DA, which includes specific DA databases or clinical records [24 - 29]. Existing Databases Various societies of anesthesiology have agreed on recommending documentation and reporting on events of DA, while there is no unanimity concerning the content of the information which must be included. Even though there are recommendations on the registration of the DA since 1990, various studies have shown that these recommendations have not been incorporated sufficiently in hospitals [26, 27]. Albeit several information transfer systems have been developed, they all have short comings. Verbal information to the patient has a high risk of not being understood or remembered, since most of the useful data are highly technical; it may be that the patient is not able to provide the information when necessary; the notification in the form of a letter or report can go astray or lack essential information; despite a systematic approach have been stipulated previously, the information in the anaesthesia monitoring records or in the medical history can, for the same reason, lack essential information and is often not accessible to other hospitals. A critical information notification proforma approach system (akin to a minimum dataset approach) should ensure the inclusion of all the essential data and their availability at the required time. DA has attempted to achieve these goals in several ways: searchable databases, on-demand centralised systems with updated information provided via telephone and alert card identifiers. The implementation of searchable databases is complex due to legal compliance with data protection requirements [24], since the information related to health en-

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joys maximum protection. The DA Austrian group was denied permission to carry out such a nationwide project by the agency of protection of data of Austria ban. The databases have two main objectives: identify specific patients for safety and collect data to learn about epidemiology and etiology of the DA. There are 3 types of databases: 1. Patient safety databases. 2. Epidemiological and aetiological databases. 3. Databases with a combination of both. Type 1: Databases for Patient Safety They aim to protect patients from adverse effects associated with the VA during current and future hospital stays. They are usually limited to a single location and anesthetic practice. An example is the “Veterans Affairs Healthcare”. Type 2: Etiological and Epidemiological Databases An example is the ASA closed claims project, which is the most recognised and widely used. Since its creation in 1984, it has analysed anesthesia-related events that have resulted in legal complaints in the United States, with the caveat that the analysis is limited to legal claims associated with DA which has resulted in morbidity or mortality. Type 3: Databases Combined (Epidemiological, Etiological and for the Safety of the Patient) An example is the Medic Alert Foundation: difficult airway / intubation registry. It aims to develop mechanisms to standardise the documentation of the VA, set up national and international databases and determine whether the distribution of this information can prevent future adverse effects. It records events between 1992 and 2014, with 12,000 patients from more than 150 health institutions included. Professionals can fill out a form to give to the patient or it can be reported online. Identification of Patients and Clinical Practices Techniques and devices that are used successfully in intubation may vary with the situation. One may wonder how this information can be transmitted to the professional.

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The ASA guidelines recommend DA documentation & communication, with a description of the difficulties encountered & techniques used. Items to record are: ● ● ● ●

● ● ●

Date and place. Professional contact details. Features of BMI, VA, comorbidity. Difficulty (manual ventilation, ventilation with a laryngeal mask, intubation, extubation). Failed techniques. Successful techniques. Recommendation Medical Alert registration.

Disclosure of the Documentation of the Anaesthesia Record This information should be first and foremost clear and accessible to all healthcare professionals. It is traditionally featured in the form of a note in the patient's history folder. With the incorporation of electronic patient records, many systems have the possibility of adding an “electronic flag” in the history which is shown whenever the record is accessed [30, 31]. ●

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Consultation: In 2003, ASA guidelines recommended that the anaesthesiologist notify the existence of a DA to the patient and/or family. Sometimes, information is not effective (pain, post surgery’s anxiety), and later, even up to 50% of patients do not recall having a conversation with the anesthesiologist [32]. For this reason, the best approach is to inform the patient and back it up with written information. In some hospitals, it is structured within a DA questionnaire. It is also backed up with a letter with instructions to keep by the patient, if needed in the future. Hospital bracelet: Sometimes, bracelets of different colours are used to alert regarding important comorbidities, allergies etc. One issue is the lack of standardization of colours and alerts, which can lead to confusion. The use of a DA bracelet could increase the safety of the patient, but it should not be used as a single measure. Screening of non-surgical patients: Many non-surgical hospitalised patients may have an underdiagnosed DA and identifying these patients ought to be considered. All the healthcare professionals should be instructed and trained on the importance of accurate evaluation of the patient, which might help reduce the incidence of encountering DA in the operating room. Patients with suspicion of DA could be subsequently referred to specialist consultation for DA for in-depth evaluation. Difficult Airway Cards: The creation of an alert card ID is a simple method that

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causes minimum disruption to the patient, as evidenced by a previous Danish study and, also the community of Madrid in December 2011. The British DAS has just started an identical pilot project, as mentioned previously, Fig. (1). The Working Group of Difficult Airway in SAR Madrid initiative has its roots in the conviction that the identification card passport is an ideal option to ensure adherence to DA objectives, without excluding the possibility of supplementing the information with other methods. This was facilitated by the fact that its implementation in the community of Madrid was expected to be simple, since it exploited the already existing interhospitalary shared information with the DA included (Fig. 2).

Fig. (2). Difficult Airway Card Working. Group of difficult airway in SAR Madrid.

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BIG DATA Patients information stored in databases is not provided if anesthetists are not able to manage it, process it, analyse it, and find issues on which to work. This is what promises to make Big Data. Big Data, aggregate or mass data refers to the storage of large amounts of data procedures used for finding repeating patterns within an amalgamation of the following data: structured data, stored in a traditional database, such as hospital records; unstructured data, not organized under the data relational model, such as text, images, audio and video files; semi-structured data, not set in traditional relational databases but with an internal organization that facilitates its treatment and analysis, such as XML documents, data stored on NoSQL databases. The analysis and management of enormous volumes of data that cannot be handled in a conventional manner may be done by biomedical sensors, imaging tests (CT scans, MRI), audio files, camera footage etc. Its purpose, just like conventional analytical systems, is to convert data into information that facilitates decision making, even in real time. The question that may be posed is whether the analysis of data made available in the history using Big Data techniques (especially those relating to the airway) would help improve the outcomes of a potential DA [33, 34]. At present, exploiting large databases created with the implementation of HCDSNS is one of the potentials uses of Big Data, which would aid in the collection of epidemiological data in DA prediction research. Big Data analysis offers us a helpful tool to discern between significant and nonsignificant variables [35, 36]. However, to infer value to this data and detect trends on the impact on patients managed in different centres or by different doctors (and not only applied to individuals but of the whole population), predictive models will allow us to apply optimised patient care and, therefore, use healthcare resources in the most intelligent manner and at a lower cost. The concept of Big Data is a new approach to making decisions. There are technical problems, such as the fragmentation of electronic systems and interoperability (Fig. 3), quality information and development in epidemiologic designs and Chi-square analysis methods to improve the strength of the causal analysis. THE PROBLEM OF INTEROPERABILITY Healthcare models are in a process of constant adaptation and, therefore, in continuous transformation. Nowadays, patients are acquiring an increasingly

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active role in their care process and, as experts, public health administration and healthcare providers are aware that it is necessary to focus on the patient as an active part of the care process. The patient has been referred to as the “main player of the organizational interoperability” by some authorities [37].

Fig. (3). Interoperability in Spanish clinical record (HCDSNS). Green: community connected. Blue: community non-connected. googl/zGzAEf.

Industry will be able to provide solutions that allow the development of a model according to three essential development keys: ● ● ●

Legislation cannot be an impediment to the development of interoperability. Confidentiality of information is an essential requirement. The cultural evolution of patients and professionals is required so that patients’ access to their health information becomes the norm.

In this not-so-distant future healthcare model, access to clinical information will be in the hands of the patient, who will play a more active role in their care and greater autonomy in the therapeutic process. Having ownership of their health information, patients may make use of the healthcare system with a full guarantee of continuity of care and efficiency of processes. The timeline of information

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transfer between professionals and patients may develop as follows: 1. Professionals record clinical information into their systems. 2. Information is available to other professionals and to the patient. 3. The patient can access reports and save them as appropriate on a platform of their choice. 4. The patient can attend any healthcare centre with complete clinical information. OTHER PROBLEMS Beyond the issues afore mentioned, healthcare systems are facing specific barriers resulting in the inability to use huge amount of data in research, evaluation and improvement of patient care. This is the result of the instability and weakness of a wide range of healthcare research structures that cannot afford even a small part of the knowledge that defines the healthcare systems. There is also a need for greater transparency in the information conveyance process and improvement of the speed in which data from health organizations is accessed. Digital communication has an increasingly vital importance in the relationship between service user and healthcare professionals. According to some recent studies, more than 80% of patients forget what is told to them in medical consultation, and up to 93% of patients prefer communication via e-mail with their doctors [38]. Furthermore, another issue that must be considered is the ownership of data. The maintenance of data privacy should occupy a prominent place. In Spain, this area is highly regulated, and there is a legislation on data protection, biomedical research, patients’ rights and so on, to ensure adequate compliance. Even though to improve how it will handle the data from the clinical history has failed, the profiles of patients will be defined. As the doctor who cares for the patient in the pre-, intra- and post-operative period, the anesthesiologist has access to large amounts of relevant similar data. The ability to analyse this data efficiently has important consequences in future care and treatment options, especially in the operating room. Moreover, the ability to quickly process data facilitates the identification of pathological states and subsequent early treatment [39]. Using Big Data-based analysis, researchers can analyse thousands of millions of items of data collected during the perioperative period to identify patients at a risk of adverse intra and post-operative events. Through the development of early warning systems, Big Data analysis provides proactive rather than reactive patient care support.

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However, the anesthetist must be cautious when it comes to substantiating the safety of a given patient through the data based on Big Data analysis, particularly when attempting to ascertain the incidence of rare events. It is essential to keep in mind that most of the difficult airway situations are and will remain unexpected. Big Data does not only allow the analysis of millions of electronic health records, request systems and medical prescriptions (electronic prescription, laboratory tests, referrals etc.) but also of support systems for the management of the storage systems, sharing of images and a long series of databases built for clinical purposes, including administrative and statistical databases. This is the so-called Real world data (RWD) [40], that allows us to analyse the benefits and adverse effects of medical decisions in clinical practice. It will be a reflects the real care that patients receive in each particular context and the results actually obtained, leaving behind evidence-based medicine (EBM) and getting closer to personalized medicine. CONCLUSION ●

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It is a must to fill out appropriate documentation after each intervention on the airway, difficult or otherwise, making specific mention of: ease of ventilation with a face mask or supraglottic device; a device used to perform tracheal intubation; obtained vision; the number of attempts. Evidence of a prior DA, with direct laryngoscopy and intubation failure, should make us suspect that we will find a similar situation in subsequent events. Nevertheless, anticipating a DA will not serve if the strategy to manage the airway does not change based on one's knowledge. The previous history of DA is not enough as a single predictor of further DA. It is essential to have available data on ventilation with a mask in the previous procedure, as it is the true indicator of morbidity in the difficult airway. Despite the fact that finding an unplanned DA is associated with significant morbimortality, in practice, the information passed on is always poor, which complicates monitoring and subsequent surgery, mostly by an unprepared anesthesiologist approach and/or procedures at different hospitals. It should improve the interoperability between health systems so that the interhospital records are easily accessible.

CONSENT FOR PUBLICATION Not applicable. CONFLICT OF INTEREST The authors confirm that this chapter's content has no conflict of interest.

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CHAPTER 24

Bibliometrics of the Difficult Airway Miguel Ángel García Aroca1, Andrés Pandiella Dominique2 and Ricardo Navarro Suay3,* Glorieta del Ejército número 1, CP: 28047 Madrid, Spain Research Institute on Higher Education and Science (INAECU), Madrid, Spain 3 Anesthesia and Critical Care Unit, Hospital Central de la Defensa “Gómez Ulla”, Madrid, Spain 1 2

Abstract: Bibliometrics or citation analysis, the statistical analysis of written publications, is an increasingly popular approach for the assessment of scientific activity. Using databases, a search of published manuscripts on the difficult airway from January, 1981 to December, 2013 was conducted. 2,412 articles were identified and analyzed as a group to assess the indicators of productivity, collaboration, and impact over this time period. There has been an increase in the productivity over the study period, with 37 manuscripts published between 1981 and 1990, and 1,268 between 2001 and 2010 (P