The Difficult Airway : A Practical Guide 9780199344246, 9780199794416

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The Difficult Airway: A Practical Guide

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The Difficult Airway: A Practical Guide Edited by

Carin A. Hagberg, MD Joseph C. Gabel Professor and Chair Department of Anesthesiology University of Texas Medical School at Houston Houston, Texas

Carlos A. Artime, MD Assistant Professor Department of Anesthesiology University of Texas Medical School at Houston Houston, Texas

William H. Daily, MD Assistant Professor Department of Anesthesiology University of Texas Medical School at Houston Houston, Texas

1

3 Oxford University Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide. Oxford New York Auckland Cape Town Dar es Salaam Hong Kong Karachi Kuala Lumpur Madrid Melbourne Mexico City Nairobi New Delhi Shanghai Taipei Toronto With offices in Argentina Austria Brazil Chile Czech Republic France Greece Guatemala Hungary Italy Japan Poland Portugal Singapore South Korea Switzerland Thailand Turkey Ukraine Vietnam Oxford is a registered trademark of Oxford University Press in the UK and certain other countries. Published in the United States of America by Oxford University Press 198 Madison Avenue, New York, NY 10016 © Oxford University Press 2013 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, by license, or under terms agreed with the appropriate reproduction rights organization. Inquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above. You must not circulate this work in any other form and you must impose this same condition on any acquirer. Library of Congress Cataloging-in-Publication Data The difficult airway : a practical guide / edited by Carin A. Hagberg, Carlos A. Artime, William H. Daily. p. ; cm. Includes bibliographical references and index. ISBN 978–0–19–979441–6 (alk. paper) I. Hagberg, Carin A. II. Artime, Carlos A. III. Daily, William H. [DNLM: 1. Airway Management. WF 145] 615.8′36—dc23 2012035304 This material is not intended to be, and should not be considered, a substitute for medical or other professional advice. Treatment for the conditions described in this material is highly dependent on the individual circumstances. And, while this material is designed to offer accurate information with respect to the subject matter covered and to be current as of the time it was written, research and knowledge about medical and health issues is constantly evolving and dose schedules for medications are being revised continually, with new side effects recognized and accounted for regularly. Readers must therefore always check the product information and clinical procedures with the most up-to-date published product information and data sheets provided by the manufacturers and the most recent codes of conduct and safety regulation. The publisher and the authors make no representations or warranties to readers, express or implied, as to the accuracy or completeness of this material. Without limiting the foregoing, the publisher and the authors make no representations or warranties as to the accuracy or efficacy of the drug dosages mentioned in the material. The authors and the publisher do not accept, and expressly disclaim, any responsibility for any liability, loss or risk that may be claimed or incurred as a consequence of the use and/or application of any of the contents of this material. 9 8 7 6 5 4 3 2 1 Printed in the United States of America on acid-free paper

Dedicated to my family in gratitude for their love and support. – Carin A. Hagberg

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Acknowledgments I would like to sincerely acknowledge the scholarly efforts of all the contributors, who I consider to be both friends and colleagues at the University of Texas Medical School at Houston, especially my Associate Editors, Carlos Artime, MD and William Daily, MD. I would also like to thank my publisher for her patience and my assistant, Naz Hassan, for her devoted efforts on my behalf. — Carin A. Hagberg

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Preface The Difficult Airway: A Practical Guide is designed for airway managers of all specialties who want to improve their success with modern airway devices and techniques in their clinical practice. The approach to airway management has changed considerably in the last 20 years, and many technological improvements have been made during this time. However, many techniques were introduced after some clinicians completed their training. This book will fill a niche for teachers and students alike who practice airway management. This paperback is a unique handbook that serves as a key resource for all airway managers, regardless of their experience and training. It is a practical, portable clinical handbook that cuts to the chase and provides the reader with the necessary tips that will increase their understanding and success rate in the use of the many airway devices and techniques currently available to the clinician. These tips apply to both basic and advanced airway skills. The contributors provide a succinct and practical structured format that encourages hands-on, active learning similar to the workshops of most major meetings that educate those interested in airway management.

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Contents Contributors xiii

Chapter 1: Airway Assessment

1

Ankur Khosla and Davide Cattano

Chapter 2: Preparation for Awake Intubation

9

Carlos A. Artime

Chapter 3: Preoxygenation Strategies and Positioning Tips Henrique Vale and Davide Cattano

Chapter 4: Mask Ventilation

35

William H. Daily

Chapter 5: Nasotracheal Intubation

41

William H. Daily

Chapter 6: Supraglottic Airway Devices

47

William H. Daily

Chapter 7: ETTs and Laryngoscopy Techniques William H. Daily

Chapter 8: Intubation Stylets

83

Lara Ferrario

Chapter 9: Flexible Fiberoptic Intubation Carlos A. Artime

97

63

27

xii

Chapter 10: Retrograde Intubation

109

Katherine C. Normand and A. Paul Aucoin

Chapter 11: Percutaneous Transtracheal Jet Ventilation

117

Katherine C. Normand

Chapter 12: Cricothyrotomy

125

Contents

Katherine C. Normand

Chapter 13: Extubation Catheters

135

Lara Ferrario

Chapter 14: Combination Techniques

143

Jay R. Pinsky and Carin A. Hagberg

Chapter 15: Pediatric Airway Management

155

Ranu Jain

Chapter 16: Difficult Airway Supplies

165

William H. Daily

Chapter 17: Special Considerations for Out of the Operating Room and Cardiopulmonary Resuscitation 169 Sam D. Gumbert

Chapter 18: Communication of the Difficult Airway and Dissemination of Critical Airway Information Sam D. Gumbert Index 183

177

xiii

Contributors Carlos A. Artime, MD

Sam D. Gumbert, MD

Assistant Professor Department of Anesthesiology University of Texas Medical School at Houston Houston, Texas

Assistant Professor Assistant Director, Residency Program Medical Director, Case Western Reserve Anesthesia Assistant Program Department of Anesthesiology University of Texas Medical School at Houston Houston, Texas

A. Paul Aucoin, MD Anesthesiology Group Associates Baton Rouge, Louisiana Davide Cattano, MD, PhD Assistant Professor Medical Director, Preoperative Anesthesia Clinic Department of Anesthesiology University of Texas Medical School at Houston Houston, Texas William H. Daily, MD Assistant Professor Director, Operating Rooms Department of Anesthesiology University of Texas Medical School at Houston Houston, Texas Lara Ferrario, MD Assistant Professor Director, Neuroanesthesia Department of Anesthesiology University of Texas Medical School at Houston Houston, Texas

Carin A. Hagberg, MD Joseph C. Grabel Professor and Chair Department of Anesthesiology University of Texas Medical School at Houston Houston, Texas Ranu Jain, MD Assistant Professor Education Coordinator, Pediatric Anesthesia Department of Anesthesiology University of Texas Medical School at Houston Houston, Texas Ankur Khosla, MD, MBA, MS Department of Anesthesiology University of Texas Medical School at Houston Houston, Texas

Contributors

xiv

Katherine C. Normand, MD Assistant Professor, Education Coordinator, Neuroanesthesia Director, 3rd and 4th Year Clerkship Department of Anesthesiology University of Texas Medical School at Houston Houston, Texas

Jay R. Pinsky, MD Medical Anesthesia Associates Houston, Texas Henrique Vale, MD Department of Anesthesiology University of Texas Medical School at Houston Houston, Texas

1

Chapter 1

Airway Assessment

Ankur Khosla, MD, MBA, MS and Davide Cattano, MD, PhD

Objectives • Understand the importance of a methodical and thorough airway assessment. • Identify the key features of a patient history that have implications for a difficult airway with respect to difficult mask ventilation, difficult laryngoscopy, difficult intubation, difficult supraglottic device placement, and difficulty with invasive techniques for airway management. • Provide an overview of the tools available for airway management with respect to airway assessment.

Introduction Maintaining the airway in a controlled fashion is the most critical step in the care of patients during surgical procedures. For many years, difficulty with airway management has been the leading cause of morbidity and mortality in the perioperative period and it maintains an important role when planning anesthetic care. The incidence of difficult mask ventilation or difficult intubation in surgical patients has been reported to be as high as 10%. Therefore, careful assessment and planning are critical to successful airway management. It is important that anesthesiologists become familiar with the anatomy of the airway, patient variables that affect that anatomy, and the tools available to help the anesthesiologist secure the airway. A difficult airway can become apparent and problematic in four different areas of airway management. Starting from the onset of general anesthesia, there is the possibility of difficult mask ventilation, followed by a difficult laryngeal view during laryngoscopy and difficult intubation. In addition, if all attempts at intubation fail, then there may be difficulty with establishment of an invasive airway. A relatively unexplored area is that of difficult supraglottic device placement or difficult ventilation with a supraglottic device. Because their use could be primary, or secondary as a rescue

2

device, familiarity with the use of supraglottic airway devices in both routine and emergent airway management is fundamental. .

1 Airway Assessment

History and Physical Emergent anesthetic inductions and intubations occur significantly less frequently than elective inductions and intubations. If time allows, conducting a formal assessment of the patient can prove to be invaluable, as it allows for appropriate planning. A thorough history includes current medications, allergies, last oral intake, evaluation of comorbid conditions, and prior difficult airway management. Approaching the evaluation by organ systems helps to keep management strategies organized and also helps in documentation for communication with other health-care providers. For example, neurological status is an important indicator, as an obtunded patient may not allow an in-depth airway evaluation, and protecting the airway becomes a necessity. Confounding variables, such as prior surgeries or advanced pathology, may affect clinical management, as in the case of cervical vertebral fusion, severe trauma, or advanced carcinoma involving the oropharynx. Assessing the potential effects of positive pressure ventilation on each patient’s cardiorespiratory status is key; for example, a tiny pneumothorax could quickly develop into a tension pneumothorax requiring invasive decompressive maneuvers. Careful consideration to these details will allow better preparation for difficulties, if they should arise. A difficult airway algorithm can be utilized in emergent or urgent airway management in patients with a “threatened” airway, in which obstruction is imminent. The clinical assessment is pivotal in defining a threatened airway and in the determination of possible airway collapse. Knowledge of the anatomic and physiologic changes that occur in both normal and diseased states is critical in the evaluation of a threatened airway. A systematic approach should assess the cause of airway collapse, including, but not limited to, infectious, neoplastic, iatrogenic, traumatic, and neuropsychiatric etiologies, and their effects on oxygenation and ventilation.

Difficult Mask Ventilation Although controversial among anesthesiologists, the authors feel that it is pivotal that the ability to ventilate be assessed prior to administration of paralytics or opioids during anesthetic induction. Difficult mask ventilation occurs when it is impossible to breathe for a patient using an airtight facemask, as a result of inherent anatomic obstruction or traumatic injury. The presence of excessive facial hair, a lack of dentition, or the presence of facial deformities (as seen in various genetic disorders) may prevent an airtight seal. Redundant oropharyngeal tissue may impede airflow. Several factors have been identified as independent predictors of difficult mask ventilation and can be summed up with the mnemonic FACES—Facial hair, Age greater than 55 years, Chubby (BMI > 26 kg/m2), Edentulous, Snoring history. A large neck circumference (male > 45 cm, female > 40 cm) indicates the risk for sleep apnea, airway obstruction, difficult mask ventilation, and/ or difficult laryngoscopy. In obese patients, the distribution of fat (apple- vs. pear-shaped) is also important. Mask ventilation can be facilitated with the use of nasal trumpets or oral airways in most causes of difficult ventilation. Because facial hair impedes a tight mask seal, options include shaving the patient or the application of occlusive dressings (e.g., Tegaderm™) over the beard. The importance of correct hand positioning, patient positioning in the “sniffing position” (Figs. 1.1 and 1.2), and proper jaw thrust are paramount. If these steps are unsuccessful, however, one must consider employing a supraglottic airway device such as a laryngeal mask airway (LMA) or a Combitube.

3 Predictors of Difficult Mask Ventilation (FACES): • Facial hair • Age > 55 years • Chubby (BMI > 26 kg/m2) • Edentulous • Snoring history

Figure 1.1 The “sniffing position”—flexion of the cervical spine at C6-C7 with extension at C1-C2.

Figure 1.2 A patient in whom difficult laryngoscopy could be expected. Reduced neck mobility, a Mallampati 3 airway, and a reduced laryngeal profile. The line drawings illustrate poor alignment of the oral and laryngeal axes.

Difficult Intubation A difficult laryngoscopy (inability to obtain adequate exposure and view of the glottic opening with conventional laryngoscopic tools) is one of the most common reasons for difficult intubation (tracheal intubation requiring multiple attempts with or without tracheal pathology). Other factors include anatomic variants secondary to pathology or trauma that may prohibit adequate

1 Airway Assessment

Tip

1 Airway Assessment

4

Figure 1.3 A patient with progressive degenerative torticollis.

mouth opening, neck extension, or maneuvering of the endotracheal tube (ETT) to the glottic opening (Fig. 1.3). Finally, the skill level of the practitioner is another variable in the determination of difficult intubation. An unskilled practitioner is likely to experience more difficulties than an experienced practitioner. Several tools have been employed to evaluate the potential for a difficult airway by assessing the patient’s anatomy. However, the sensitivity and specificity of these pretests do not always provide much utility. Specifically, a pretest indicating a difficult intubation may not always correlate with a difficult intubation. The converse also holds true: A pretest indicating an easy intubation does not necessarily mean that the intubation will be easy. Nonetheless, the following are some of the predictors that are more commonly used.

Tip • Pretest indicators of a difficult intubation or an easy intubation are neither 100% sensitive nor specific and may not always be accurate. The most obvious and reliable predictor of a difficult airway is a history of prior difficult intubation. A large body habitus with morbid obesity is a risk factor for difficult intubation. The most commonly used pretest scoring system (Mallampati Classification) evaluates the mouth opening and exposure of the patient’s soft palate, faucial pillars, uvula, and posterior pharynx (Fig. 1.4A–1.4D). This evaluation is performed while the patient is seated upright looking directly at the clinician. A Grade III or IV Mallampati Classification is associated with greater difficulty with glottic exposure during laryngoscopy. Neck extension is crucial when placing the patient in a sniffing position prior to anesthetic induction. Limited neck range of motion may indicate the possibility of a difficult laryngoscopy resulting

5 (B)

1 Airway Assessment

(A)

(D)

(C)

Figure 1.4 A–D Mallampati Airway Classification Scores. From left to right—(A) Class I: Full visibility of the tonsils, uvula, and soft palate. (B) Class II: Visibility of the hard and soft palate and the upper portions of the tonsils and uvula. (C) Class III: The soft and hard palate and base of the uvula are visible. (D) Class IV: Only the hard palate is visible.

from suboptimal positioning. Verifying that a patient can bite their top lip with their lower teeth gives feedback regarding the ability to subluxate and overall mobility of the mandible. A thyromental distance (the distance from the superior portion of the thyroid cartilage to the anterior portion of the mandible) of less than four fingerbreadths may correlate with an anterior or high glottis making the laryngoscopic view difficult. A thick neck (neck circumference > 45 cm) is associated with a short neck and poor cervical extension and has been correlated with a significant risk of failed direct laryngoscopy. With regards to describing the view of the glottis achieved during laryngoscopy, the most commonly used scoring system is that described by Cormack and Lehane. Recording the view is

6

1 Airway Assessment

(A)

Laryngoscope

(B)

Epiglottis

(C) (D)

Figure 1.5 A–D Cormack-Lehane Score for direct laryngoscopy. (A) Grade 1 (Full view of the vocal cords), (B) Grade 2 (Partial view of the vocal cords), (C) Grade 3 (Only epiglottis visible), and (D) Grade 4 (Neither the epiglottis nor glottis visualized). (From Cormack RS, Lehane J. Difficult tracheal intubation in obstetrics. Anaesthesia 1984;39:1105–1111; with permission.)

important as a way of communication to other practitioners in future situations that require airway management. The grades range from I to IV, starting at grade I (the best view), where there is a complete view of the epiglottis and vocal cords, and culminating with grade IV (the most difficult view), in which there is no visualization of the epiglottis or larynx. (Figs. 1.5A–1.5D) A modified classification scheme with five different grades based on the Cormack-Lehane scoring system was described by Yentis. Cook has described a further modification with six grades that takes into account difficulty of intubation.

Difficult Cricothyrotomy When the situation arises where one cannot ventilate by facemask or LMA and intubation is not possible, a surgical airway may need to be placed via the cricothyroid membrane (see Chapter 12). It is rare that this anatomic point has poor exposure. Reasons for suboptimal access include morbid obesity, neck immobility, or trauma to the area. Neck assessment of the patients to identify this critical landmark is rarely performed pre-operatively. In situations when difficult mask ventilation or difficult laryngoscopy is anticipated, it is advisable to identify the thyroid notch, cricothyroid membrane, and cricoid cartilage prior to induction. Recently, percutaneous tracheostomy has been increasingly used rather than percutaneous needle or open cricothyrotomy. The use of ultrasound has also been increasingly advocated as an alternative or as part of a combined assessment of external neck landmarks.

7 Tip

Supraglottic Devices Standardized recommendations for the markers to be used for assessing proper size, proper device, depth of insertion, and anticipation of difficulty with placement of supraglottic devices do not currently exist. The authors (D. Cattano) have proposed the use of different external landmarks (thyroid width, length, hyoid to cricoid distance, thyroid to cricoid distance, occipital notch to C7 tubercle), in addition to a focused history to assess the appropriate size and type of supraglottic device.

Tools for Success A thorough history and plan for airway management is invaluable. Experience with various airway management techniques is important for the development of an appropriate airway management plan, as the experienced practitioner has insight as to which technique is most applicable to each situation and is well-skilled at the use of various airway tools. Positioning the patient for ease of ventilation and maximum exposure of the glottis during laryngoscopy is very useful. The sniffing position involves flexing the cervical spine at C6-C7 with extension at C1-C2 (see Chapter 15). Access to supraglottic ventilation devices (e.g., LMA, Combitube, or King-LT) and familiarity with their function can be pivotal when mask ventilation becomes difficult. When faced with a difficult intubation secondary to a poor view of the glottis during direct laryngoscopy, changing the size or type of blade may improve the view. Video laryngoscopes (e.g., the Storz C-MAC, GlideScope, or McGrath) are also useful in the setting of failed direct laryngoscopy or when the initial airway assessment portends a difficult direct laryngoscopy (see Chapter 6). Other techniques include intubating stylets (e.g., a gum-elastic bougie), which can act as a rigid guide over which an ETT is passed (see Chapter 7). Occasionally, these measures may not be enough to secure the airway. Ultimately, having well-established back-up plans if the original approach fails is what saves the patient—hence, the importance of the pre-operative airway assessment and planning.

Summary Approaching the management of a patient’s airway in a controlled or emergent situation cannot be a one-size-fits-all method. A methodical and thorough evaluation of the airway, along with an appreciation of potentially complicating variables, will guide the plan to successful airway management. If the first approach to airway management fails, then swift progression through a pre-devised algorithm is critical for the patient’s safety. Thus, knowledge and familiarity with the various tools available for ventilation and intubation are essential.

Suggested Reading Williamson D, Nolan J. Airway Assessment. In: Benger J, Nolan J, Clancy M, eds. Emergency Airway Management. London: Cambridge University Press; 2009:19–26. Kheterpal S, Han R, Tremper KK, Shanks A, Tait AR, O’Reilly M, et al. Incidence and predictors of difficult and impossible mask ventilation. Anesthesiology 2006;105(5):885–891.

1 Airway Assessment

• Prior to induction, if there is the expectation of a difficult airway, locate the cricothyroid membrane and denote the location on the skin with a marker.

1 Airway Assessment

8

Cattano D, Cavallone L. Airway Management and Patient Positioning: A Clinical Perspective. Anesthesiology News 2011;37(8):17–23. Shiga T, Wajima Z, Inoue T, Sakamoto A. Predicting difficult intubation in apparently normal patients: a meta-analysis of bedside screening test performance. Anesthesiology 2005;103(2):429–437. Koh LK, Kong CE, Ip-Yam PC. The modified Cormack-Lehane score for the grading of direct laryngoscopy: evaluation in the Asian population. Anaesth Intensive Care 2002;30(1):48–51.

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Chapter 2

Preparation for Awake Intubation Carlos A. Artime, MD

Objectives • Explain the indications and rationale for awake intubation. • Discuss premedicants and sedatives that are useful for preparation of a patient for awake intubation. • List the various methods for topicalization of the airway with local anesthetics. • Describe the most common airway nerve blocks and their use in awake intubation.

Introduction The ASA Task Force for Management of the Difficult Airway defines the difficult airway as “a clinical situation in which a conventionally trained anesthesiologist experiences difficulty with mask ventilation, difficulty with endotracheal intubation, or both.” In a patient with a known or suspected difficult airway, awake intubation is generally regarded as the safest method for securing the airway because of the following: • Patency of the airway is maintained through upper pharyngeal muscle tone. • Spontaneous ventilation is maintained. • The awake patient is easier to intubate, as the larynx moves to a more anterior position after induction of anesthesia. • The patient can still protect his or her airway from aspiration. • The patient is able to monitor his or her own neurological symptoms (e.g., the patient with potential cervical pathology). Other indications for awake intubation include severe aspiration risk, facial or airway trauma, severe hemodynamic instability, and unstable cervical spine pathology. A more comprehensive list can be found in Table 2.1. Once the decision to perform awake intubation is made, communication with the patient and psychological preparation is of the utmost importance to maximize the odds for a successful

2 Preparation for Awake Intubation

10

Table 2.1 Indications for Awake Intubation 1. History of difficult intubation 2. Anticipated difficult airway based on physical examination: Small mouth opening Receding mandible/micrognathia Macroglossia Short, muscular neck Limited range of motion of the neck (rheumatoid arthritis, ankylosing spondylitis, prior cervical fusion) Congenital airway anomalies Morbid obesity Pathology involving the airway (tracheomalacia) Airway masses (malignancy of the tongue, tonsils, or larynx; large goiter; mediastinal mass) Upper airway obstruction 3. Unstable cervical spine 4. Trauma to the face or upper airway 5. Anticipated difficult mask ventilation 6. Severe risk of aspiration 7. Severe hemodynamic instability 8. Respiratory failure

awake intubation. The practitioner should explain the specific indications for awake intubation, as well as potential complications, including local anesthetic toxicity, airway trauma, discomfort, recall, and failure to secure the airway. Operating room set-up should include routine monitors (electrocardiogram, noninvasive blood pressure, pulse oximetry, and capnography). Standard emergency medications should be available, including an appropriate IV induction agent and paralyzing agent. The equipment needed for the chosen intubation technique as well as supplemental airway equipment as delineated by the ASA Task Force should also be readily available. This includes a range of laryngoscope blade styles and sizes, tracheal tubes of assorted sizes, tracheal tube guides (e.g., stylets and bougies), laryngeal mask airways of various sizes, flexible pediatric bronchoscope, retrograde intubation equipment, and equipment suitable for emergency invasive and noninvasive airway. It is recommended that a qualified assistant be present who can help with airway management, should the need arise.

Premedication Prior to awake airway management, certain premedicants may be useful and should be considered. Antisialagogues can be used to dry airway secretions, facilitating indirect or fiberoptic laryngoscopy and increasing the effectiveness of airway topicalization. Nasal mucosal vasoconstrictors should be utilized if a nasotracheal intubation is planned. In the patient at high risk for aspiration, prophylactic medications should be administered.

Antisialagogues One of the most important goals of premedication for awake intubation is drying of the airway. Secretions can obscure the view of the glottis, especially when using flexible fiberoptic bronchoscopy. In addition, secretions can prevent local anesthetics from reaching intended areas, resulting in failed sensory blockade, or can wash away and dilute local anesthetics, diminishing their potency and duration of action. The medications most often used for their antisialagogic properties are

Table 2.2 Dosing Intravenous (IV)

Intramuscular (IM)

Dose

Onset

Duration of action

Dose

Onset

Duration of action

Glycopyrrolate

Adult: 0.1–0.3 mg IV Pedi: 4–8 μg/kg IV

1–2 minutes

2–4 hours

Adult: 0.1–0.3 mg IV Pedi: 4–8 μg/kg IV

20–30 minutes

6–8 hours

Scopolamine

Adult: 0.4 mg IV Pedi: 6 μg/kg IV

5–10 minutes

1–2 hours

Adult: 0.4 mg IV Pedi: 6 μg/kg IV

30–60 minutes

4–6 hours

Atropine

Adult: 0.4–0.6 mg IV Pedi: 10 μg/kg IV

1 minute

15–30 minutes

Adult: 0.4–0.6 mg IV Pedi: 10 μg/kg IV

15–20 minutes

2–4 hours

Table 2.3 Pharmacologic Characteristics Tachycardia

Antisialagogue effect

Sedation/Amnesia

Glycopyrrolate

++

+++

0

Scopolamine

+

+++

+++

+++

++

+

Atropine

0, no effect; +, minimal effect; ++, moderate effect; +++, marked effect (Adapted from Morgan GE Jr., Mikhail MS, Murray MJ. Clinical Anesthesiology, 3rd edition. New York: McGraw-Hill; 2002:208.)

Tips • Because of its pharmacologic profile, glycopyrrolate is the drug of choice in most clinical circumstances. If tachycardia is contraindicated (e.g., in patients with coronary artery disease or severe aortic or mitral stenosis), then scopolamine should be considered, as it is the least vagolytic. • Administer anticholinergics as early as possible for maximal effect (at least 30 minutes in advance), as they do not eliminate existing secretions but, rather, prevent new secretion formation. • If there is not enough time to administer an anticholinergic and for it to take effect, then consider using a 4″ × 4″ gauze to dry the tongue.

11

2 Preparation for Awake Intubation

the anticholinergics. These drugs inhibit salivary and bronchial secretions by way of their antimuscarinic effects. The anticholinergics used in clinical practice are glycopyrrolate, scopolamine, and atropine. These agents should be administered at least 30 minutes in advance of the planned procedure. See Tables 2.2 and 2.3 for dosing and pharmacologic characteristics of anticholinergics.

2 Preparation for Awake Intubation

12

Nasal Mucosal Vasoconstrictors The nasal mucosa and nasopharynx are highly vascular. When a patient requires nasotracheal intubation, adequate vasoconstriction is essential, as bleeding can make visualization of the larynx extremely difficult. This is especially a concern during nasal fiberoptic intubation. Nasal mucosal vasoconstrictors should be applied 15 minutes prior to nasal intubation. Several agents are available. • Cocaine 4% can be applied using cotton-tipped applicators. Maximum dose is 1.5 mg/kg to 3 mg/ kg. A benefit of cocaine is that it has both vasoconstrictive and local anesthetic effects. Caution in patients with hypertension, coronary artery disease, hyperthyroidism, pseudocholinesterase deficiency, preeclampsia, and in patients taking MAOIs. • A mixture of lidocaine 3%/phenylephrine 0.25% can be made by combining lidocaine 4% and phenylephrine 1% in a 3:1 ratio. This combination has similar anesthetic and vasoconstrictive properties as cocaine and can be used as a substitute. The mixture can be sprayed intranasally or applied with cotton-tipped applicators if viscous lidocaine is used. • Commercially available nasal decongestants containing either oxymetazoline 0.05% (Afrin) or phenylephrine 0.5% (Neo-Synephrine) may also be applied to nasal mucosa. The usual dose is two sprays in each nostril. Pediatric patients are especially sensitive to these drugs and require lower concentrations.

Aspiration Prophylaxis Routine prophylaxis against aspiration pneumonitis is no longer routinely recommended but may be beneficial in patients at high risk for aspiration (see Indications). The goal of aspiration prophylaxis is twofold: to decrease gastric volume and to decrease gastric fluid pH. Commonly used agents include non-particulate antacids (e.g., Bicitra), pro-motility agents (e.g., metoclopramide), and H2-receptor antagonists. These drugs may be used alone or in combination. See Table 2.4. Indications: • Pre-operative fasting guidelines not met (i.e., “full stomach”) • Symptomatic gastroesophageal reflux disease • Hiatal hernia • Morbid obesity • Diabetic gastroparesis • Pregnancy • Presence of a nasogastric tube

Table 2.4 Drugs used for aspiration prophylaxis Route Adult dose Pedi dose

Onset

PO

Effect on Effect on gastric volume Gastric pH

15–30 mL

0.4 mL/kg

5 min

↑

↑

Metoclopramide IV

10 mg

0.15 mg/kg

1–3 min

↓

–

H2-Antagonists Cimetidine Ranitidine Famotidine

300 mg 50 mg 20 mg

5–10 mg/kg 45–60 min 0.25–1 mg/kg 30–60 min 60–120 min 0.15 mg/kg

↓

↑

Bicitra

IV IV IV

Depending on the clinical circumstance, intravenous sedation may be useful in allowing the patient to tolerate awake intubation by providing anxiolysis, amnesia, and analgesia. Benzodiazepines, opioids, hypnotics, α2 agonists, and neuroleptics can be used alone or in combination. It is important that these agents be carefully titrated to effect, as oversedation can render a patient uncooperative and make awake intubation more difficult. Spontaneous respiration with adequate oxygenation and ventilation should always be maintained. Care should be taken in situations with critical airway obstruction, as awake muscle tone is sometimes necessary in these patients to maintain airway patency. Avoidance of oversedation is also important in the patient with a full stomach, as an awake patient can protect his or her own airway in the chance of regurgitation.

Benzodiazepines Benzodiazepines are frequently used to achieve sedation for awake intubation in combination with opioids or are used for their amnestic and anxiolytic effects when other sedatives (e.g., dexmedetomidine, ketamine, or remifentanil) are chosen as the primary agent. Three benzodiazepine receptor agonists are commonly used in anesthesia practice: midazolam, diazepam, and lorazepam. Because of its more rapid onset and relatively short duration, midazolam is the more commonly used agent. See Tables 2.5 and 2.6 for dosing and pharmacology. Systemic Effects: • CNS: amnesia, sedation/hypnosis, anti-convulsive • CV: mild decrease in systemic vascular resistance and reduction in cardiac output • Respiratory: mild decrease in respiratory rate and tidal volume; effects augmented with co-administration of opioids Reversal: • Flumazenil 0.2 mg IV, repeated as needed to a maximum dose of 1 mg • Half-life of 0.7 hours to 1.8 hours; monitor for resedation

Table 2.5 Benzodiazepine Dosing IV

IM

PO

Midazolam

1–2 mg, repeat prn (0.025–0.1 mg/kg)

0.07–0.2 mg/kg

0.25–0.5 mg/kg

Diazepam

2–4 mg, repeat prn (0.05–0.2 mg/kg)

0.05–0.2 mg/kg

0.2–0.5 mg/kg

Table 2.6 Benzodiazepine Pharmacology Relative potency

Time to peak onset

Duration

Midazolam

3

IV: 2–3 minutes IM: 15–30 minutes PO: 20–30 minutes

IV: 20–30 minutes IM: 2 hours

Diazepam

1

IV: 3–5 minutes IM: 30–45 minutes PO: 60–90 minutes

IV: 20–30 minutes

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13

Sedation

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14

Opioids Opioids, by way of their agonist effect on opioid receptors in the brain and spinal cord, provide analgesia, depress airway reflexes, and prevent hyperventilation associated with pain or anxiety. These properties make them a useful addition to the sedating regimen for awake intubation. Although any opioid receptor agonist could theoretically be used for this purpose, the synthetic phenylpiperidine class of opioids—fentanyl, sufentanil, alfentanil, and remifentanil—are best-suited to the task. These drugs are particularly useful because of their rapid onset, relatively short duration of action, and ease of titration. Systemic Effects: • CNS: analgesia, pruritus, muscle rigidity; augmentation of sedative effects of other intravenous agents • CV: bradycardia; little effect on myocardial contractility or afterload • Respiratory: respiratory depression characterized by increased tidal volume and decreased respiratory rate with an overall decrease in minute ventilation; apnea with higher doses Dosing and Pharmacology: Fentanyl • Sedative dose: 25μg to 200 μg IV (0.5–2 μg/kg) • Rapid onset within 2 to 3 minutes • Duration of a single bolus dose is roughly 30 minutes to 1 hour • Most commonly used opioid for awake intubation; usually used in combination with other agents (e.g., midazolam, propofol) Sufentanil • Sedative dose: 5μg to 20 μg IV (0.05–0.2 μg/kg) • Is 7 to 10 times more potent than fentanyl; has a similar pharmacokinetic profile after a single bolus dose Alfentanil • Sedative dose: 500μg to 1500 μg IV (10–30 μg/kg) • Very rapid onset within 1.5 to 2 minutes • Rapid recovery; duration of a single bolus dose is 10 to 15 minutes Remifentanil • Sedative dose: Bolus 0.5 μg/kg IV followed by an infusion of 0.1 μg/kg/min • Infusion can subsequently be titrated by 0.025 μg/kg/min to 0.05 μg/kg/min in 5 minutes intervals to achieve adequate sedation • Ultrashort-acting opioid; half-life of 3 minutes • May be used as a single agent or in combination with other agents (e.g., midazolam, propofol) Reversal: • Naloxone 0.04 mg to 0.08 mg IV, repeated every 3 minutes until restoration of spontaneous ventilation • Onset within 1 to 2 minutes; duration of 30 to 60 minutes

Propofol Propofol is the most frequently used intravenous anesthetic today. Its primary effect is hypnosis as a result of an unclear mechanism; however, there is evidence that a significant portion of this

Systemic Effects: • CNS: sedation/hypnosis, antiemesis, euphoria, anti-convulsive • CV: decrease in arterial blood pressure (decreases in SV, CO, and SVR) • Respiratory: decrease in tidal volume, increase in respiratory rate; decreased respiratory responsiveness to CO2; bronchodilation Dosing and Pharmacology: • Sedative dose: Intermittent doses of about 0.25 mg/kg IV or a continuous IV infusion of 25 μg/kg/min to 75 μg/kg/min titrated to effect • Onset of approximately 90 seconds • Recovery of 4 minutes to 5 minutes after an induction dose; more rapid with sedative doses

Dexmedetomidine Dexmedetomidine is a centrally acting, highly selective α2 adrenoreceptor agonist with sedative, analgesic, anxiolytic, antitussive, and antisialagogue properties that make it well suited for use in awake intubation. It causes minimal respiratory impairment, even at high doses. There are several reports of dexmedetomidine sedation for awake fiberoptic intubation, including a Phase IIIb FDA study specifically for this indication. Systemic Effects: • CNS: sedation/hypnosis, analgesia, • CV: small reduction in minute ventilation with preservation of carbon dioxide responsiveness • Respiratory: bradycardia, decreased systemic vascular resistance, cardiac output, contractility, and arterial blood pressure; hypertension during initial loading dose resulting from direct vasoconstrictive effect Dosing and Pharmacology: • Dose: Bolus 1 μg/kg over 10 minutes, followed by a continuous infusion of 0.2 μg/kg/hr to 0.7 μg/kg/hr (some patients may require higher maintenance doses) • Onset of effect in approximately 15 minutes • Half-life of 2 hours to 3 hours • Consider pretreatment with midazolam to decrease incidence of recall. • Prevent bradycardia with administration of an anticholinergic. • Reduce doses in the elderly, patients with hepatic or renal impairment, or in patients with depressed systolic function.

Ketamine Ketamine is an NMDA antagonist that produces dissociative anesthesia, which manifests clinically as a cataleptic state with eyes open and many reflexes intact, including the corneal, cough, and swallow reflexes. Its use in awake intubation has been described in combination with benzodiazepines and dexmedetomidine. Systemic Effects: • CNS: sedation/hypnosis, dissociative anesthesia, hallucinations; increase in cerebral blood flow and intracranial pressure

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hypnotic effect is mediated by interaction with GABA receptors. The use of propofol in awake intubation is well described both as a single agent and in combination with remifentanil.

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16

• CV: increased arterial blood pressure, heart rate, and cardiac output secondary to inhibition of norepinephrine reuptake; direct myocardial depression that may be unmasked in catecholaminedepleted states • Respiratory: no respiratory depression; bronchodilation; increased salivation Dosing and Pharmacology: • Sedative dose: 0.2 mg/kg to 0.8 mg/kg IV • Onset within 1 to 2 minutes; duration of hypnosis of 5 to 10 minutes • Pretreatment with an antisialagogue is imperative • Consider administration of a benzodiazepine to attenuate undesirable psychological effects.

Droperidol Droperidol is a neuroleptic medication occasionally used in anesthesia practice for its sedative and anti-emetic properties. Its mechanism of action is antagonism of dopamine receptors in the central nervous system. In combination with fentanyl, it produces a state of hypnosis, analgesia, and immobility classically referred to as neuroleptanalgesia. Neuroleptanalgesia can be used for awake intubation with favorable results. Systemic Effects: • CNS: sedation, cataleptic immobility; no anxiolysis; extrapyramidal symptoms • CV: QT prolongation, mild vasodilation, and reduction in arterial blood pressure • Respiratory: no significant effect Dosing and Pharmacology: • Sedative dose: 2.5 mg to 5 mg IV • Onset in 15 to 20 minutes; half-life of approximately 2 hours • Should be administered with a benzodiazepine for amnesia and anxiolysis • Contraindicated in patients with QT prolongation (>440 msec for males, >450 msec for females) • ECG should be performed during and for 2 hours to 3 hours after treatment

Tips Combining different classes of sedative medications allows for lower doses, quicker recovery, and a lower incidence of recall. Some well-studied combinations include: • Midazolam and fentanyl • Propofol and remifentanil • Propofol, fentanyl, and midazolam • Dexmedetomidine and midazolam • Droperidol, fentanyl, and midazolam

Airway Anesthesia Numbing of the airway with local anesthetics should, in most cases, be the primary anesthetic for awake intubation. Topicalization is often sufficient; if supplemental anesthesia is required, then a variety of nerve blocks may be utilized. These techniques may be used in many different combinations as long as the maximum dosage of local anesthetic is not exceeded.

Concentration

Speed of onset

Duration

Maximum dosage

Lidocaine

2%–4% for topicalization; 1%–2% for local infiltration and nerve blocks

2–5 minutes

30–60 minutes

8 mg/kg for airway topicalization (5 mg/kg for local infiltration w/o epinephrine)

Cocaine

4% solution

3 minutes

30–60 minutes

1.5 mg/kg

Benzocaine

20% spray

1 minute

30–60 minutes

100 mg

Tetracaine

0.5%–1% solution

3 minutes

30–60 minutes

100 mg

Local Anesthetics When using local anesthetics, it is important to be familiar with the speed of onset, duration of action, optimal concentration, signs and symptoms of toxicity, and the maximum recommended dosage of the drug chosen. The rate and amount of topical local anesthetic absorption vary depending on the site of application, the concentration and total dose of local anesthetic applied, the hemodynamic status of the patient, and individual patient variation. Local anesthetic absorption is more rapid from the alveoli than from the tracheobronchial tree, where it is more rapid than from the pharynx. Lidocaine and cocaine are the most commonly used agents for topical anesthesia of the airway. See Table 2.7. Signs of Local Anesthetic Toxicity: • Early symptoms: euphoria, dizziness, tinnitus, confusion, perioral numbness, metallic taste • Severe toxicity: seizures, respiratory failure, loss of consciousness, circulatory collapse Special Considerations: • Cocaine: caution in patients with hypertension, coronary artery disease, hyperthyroidism, pseudocholinesterase deficiency, preeclampsia, and in patients taking monoamine oxidase inhibitors • Benzocaine: risk of methemoglobinemia (early symptoms of cyanosis, tachycardia, and tachypnea leading to stupor, coma, and death) → treatment with methylene blue 1 mg/kg to 2 mg/kg IV

Topicalization Techniques Atomizers: • A standard DeVilbiss Atomizer with the bulb removed. The atomizer reservoir is filled with 2% to 4% lidocaine. Oxygen tubing is connected from the atomizer to an oxygen cylinder with a flow rate of 8 L/min to 10 L/min. A bleed hole is cut in the oxygen tubing, allowing for intermittent application of the local anesthetic when a thumb is placed over the hole in the tubing. • Disposable plastic atomizer (Fig. 2.1). This device is attached to an oxygen tank with a flow rate of 8 L/min to 10 L/min and the phalange is depressed to deliver the local anesthetic solution to the oropharyngeal mucosa. • MADjic Mucosal Atomization Device (Wolfe Tory Medical, Salt Lake City, UT) is an inexpensive, disposable, latex-free device that, when attached to a Luer fitted syringe containing local anesthetic, can be used to dispense a fine mist to the oropharyngeal or nasal mucosa (Fig. 2.2). The tubing is malleable, allowing for delivery of local anesthetic to deeper pharyngeal structures and the glottis.

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Table 2.7 Commonly Used Local Anesthetics

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18

Figure 2.1 Typical disposable atomizer. From Hagberg CA, ed., Benumof’s Airway Management, 3rd ed., St Louis: Mosby; 2012.

Figure 2.2 MADjic Mucosal Atomization Device (Wolfe Tory Medical, Salt Lake City, UT). From Hagberg CA, ed. Benumof’s Airway Management, 3rd ed., St Louis: Mosby; 2012.

Tip Using the MADjic atomizer with a syringe instead of a standard DeVilbiss atomizer allows for a known amount of local anesthetic to be administered. This helps to ensure that the maximum dose is not exceeded. Nebulizers: • A standard mouthpiece-type nebulizer (Fig. 2.3) can be used to topicalize the oropharynx and trachea. Oxygen flow rates of 5 L/min to 8 L/min should be used to ensure that the nebulized particle size is large enough to adequately anesthetize the upper airway.

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Figure 2.3 Typical mouthpiece-type nebulizer. From Hagberg CA, ed., Benumof’s Airway Management, 3rd ed., St Louis: Mosby; 2012.

• A facemask-type nebulizer (Fig. 2.4) can be used if nasal cavity anesthesia is needed; the patient is instructed to breathe in through the nose. • Because the patient does not cough or gag, this approach is especially advantageous in patients with increased intracranial pressure, open eye injury, and severe coronary artery disease. • A typical dose of lidocaine used in a standard nebulizer is 4 mL of 4% lidocaine. This results in a total dose of 160 mg of lidocaine, which is well within the safe dosage range. To aid in nasal vasoconstriction, 1 mL of 1% phenylephrine may be added to the 4% lidocaine.

Tip Administer nebulized lidocaine prior to other airway anesthetics (e.g., atomization, intraoral, or intranasal nerve blocks) to minimize coughing, gagging, and patient discomfort.

Direct Application: • “Lidocaine lollipop”: Lidocaine 5% ointment or viscous lidocaine 2% to 4% is placed on the end of a tongue depressor and placed lidocaine-side-down onto the posterior tongue. The patient is encouraged not to swallow but, rather, allow the lidocaine to “melt” and run down the base of the tongue and pool above the glottis, where it is then aspirated. • The “toothpaste method” is a similar concept and involves placing a line of lidocaine 5% ointment down the middle of the tongue. The patient is instructed to place the tongue against the roof of the mouth and is encouraged not to swallow. • “Gargle and spit”: The patient is administered 15 mL of viscous lidocaine 2% to 4% and instructed to gargle the preparation for at least 15 seconds before spitting it out. Allow 4 minutes to 6 minutes for adequate anesthesia to set in. • Nasal anesthesia can be achieved by placing cotton pledgets or cotton-tipped swabs soaked in cocaine 4%, lidocaine 4% with epinephrine 1:200,000, or a 3:1 mixture of lidocaine 4% and phenylephrine 1% in the nares. A similar preparation using viscous 4% lidocaine can be applied using a syringe attached to a 14-g angiocatheter.

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20

Figure 2.4 Typical facemask-type nebulizer. From Hagberg CA, ed., Benumof’s Airway Management, 3rd ed., St Louis: Mosby; 2012.

• The “spray-as-you-go” technique involves injecting local anesthetics through the suction port of a fiberoptic bronchoscope (FOB). One method requires attaching a triple stopcock to the proximal portion of the suction port to connect oxygen tubing from a regulated oxygen tank set to flow at 2 L/min to 4 L/min. Under direct vision through the bronchoscope, targeted areas are sprayed with aliquots of 0.2 mL to 1.0 mL of 2% to 4% lidocaine. The physician then waits 30 seconds to 60 seconds before advancing to deeper structures and repeating the maneuver. The flow of oxygen allows higher FiO2 delivery, keeps the FOB lens clean, disperses mucous secretions away from the lens, and aids in nebulizing the local anesthetic. A second method involves passing a multi-orifice epidural catheter (internal diameter of 0.5–1.0 mm) through the suction port of an adult FOB and intermittently administering aliquots of 0.2 mL to 1.0 mL of 2% to 4% lidocaine.

Tip The “spray-as-you-go” technique is especially useful in patients who are at risk for aspirating gastric contents because the topical anesthetic is applied only seconds before the intubation is accomplished and allows the patient to maintain his or her airway reflexes as long as possible.

Because of the multitude of nerves innervating the airway, there is no single anatomic site where a physician can perform a nerve block and anesthetize the entire airway. Although topicalization of the mucosa serves, in the majority of patients, to anesthetize the entire airway adequately, some patients require supplementation to ablate sensation in the nerve endings running deep to the mucosal surface, such as the periosteal nerve endings of the nasal turbinates and the stretch receptors at the base of the tongue, which are involved in the gag reflex. Sphenopalatine Nerve Block (Fig. 2.5A): • This block provides anesthesia of the nasal cavity, as well as the roof of the mouth, soft palate, and tonsils. • Equipment: Long cotton-tipped applicators or cotton pledgets soaked in either 4% cocaine or 4% lidocaine with epinephrine 1:200,000; bayonet forceps (if using pledgets) • Technique: Apply the cotton-tipped applicator along the upper border of the middle turbinate at approximately a 45° angle to the hard palate and directed posteriorly until the upper posterior wall of the nasopharynx (sphenoid bone) is reached. The sphenopalatine ganglion underlies the mucosal surface at this point. The applicator is left in place for approximately 5 minutes to 10 minutes. • Alternatively, cotton pledgets soaked in the local anesthetic solution may be used and applied to the nasal cavity in the same manner using bayonet forceps.

A

B Figure 2.5 Left lateral view of the right nasal cavity, showing long cotton-tipped applicators soaked in local anesthetic. (A) Applicator angled at 45° to the hard palate with cotton swab over mucosal surface overlying the sphenopalatine ganglion. (B) Applicator placed parallel to the dorsal surface of the nose, blocking anterior ethmoidal nerve. (From University of California, Irvine, Department of Anesthesia: D.A. Teaching Aids; Reprinted with permission from Hagberg CA, ed., Benumof’s Airway Management, 2nd ed., St. Louis: Mosby; 2007.)

Tip Because it provides anesthesia of the roof of the mouth and soft palate, a sphenopalatine block is useful even when a transoral intubation is planned.

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Airway Nerve Blocks

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22

Anterior Ethmoidal Nerve Block (Fig. 2.5B): • This block provides anesthesia of the anterior portion of the nasal cavity. • Equipment: Long cotton-tipped applicators soaked in either 4% cocaine or 4% lidocaine with epinephrine 1:200,000 • Technique: Insert the cotton-tipped applicator into the nare parallel to the dorsal surface of the nose until it meets the anterior surface of the cribriform plate. The applicator is held in position for 5 minutes to 10 minutes. Glossopharyngeal Nerve Block (Fig. 2.6): • This block primarily targets the lingual branch of the glossopharyngeal nerve (CN IX), providing anesthesia to the posterior third of the tongue and blocking the afferent limb of the gag reflex. Some blockade of the more proximal branches of CN IX may be achieved, providing anesthesia of the vallecula, anterior surface of the epiglottis, posterior and lateral walls of the pharynx, and tonsillar pillars. • Equipment: Tongue blade or Mac 3 laryngoscope; 25 g spinal needle attached to a 5 mL syringe containing 1% to 2% lidocaine • Positioning: Place the patient in the sitting position and stand facing the patient on the contralateral side of the nerve to be blocked. Instruct the patient to open his/her mouth widely and protrude the tongue. • Technique: With the non-dominant hand, displace the tongue medially with a tongue blade or a Mac 3 laryngoscope blade, forming a gutter or trough along the floor of the mouth between the tongue and the teeth. The gutter ends in a cul-de-sac formed by the base of the palatoglossal arch (also known as the anterior tonsillar pillar), which is a U- or J-shaped structure starting at

Tongue

Gutter

Figure 2.6 Glossopharyngeal nerve block, anterior approach. Tongue displaced medially forming a gutter (glossogingival groove), which ends distally in a cul-de-sac. A 25 gage spinal needle is placed at the base of the palatoglossal fold. (From University of California, Irvine, Department of Anesthesia: D.A. Teaching Aids; Reprinted with permission from Hagberg CA, ed., Benumof’s Airway Management, 2nd ed., St. Louis: Mosby; 2007.)

Tip Consider a glossopharyngeal nerve block when planning to perform awake direct laryngoscopy, awake videolaryngoscopy, or in patients with a pronounced gag reflex. Superior Laryngeal Nerve Block (Fig. 2.7): • This block provides anesthesia of the hypopharynx and upper glottis, including the vallecula and the laryngeal surface of the epiglottis. • Equipment: 25 g spinal needle attached to a 5 mL syringe containing 1% to 2% lidocaine

A

Superior laryngeal nerve Cornu of hyoid bone

Fat pad

Cornu of thyroid

B C

Thyrohyoid membrane

Figure 2.7 Superior laryngeal nerve block, external approach. (A) using the greater cornu of the hyoid bone as landmark; (B) using the superior cornu of the thyroid cartilage as landmark; and (C) using the thyroid notch as landmark. (From University of California, Irvine, Department of Anesthesia: D.A. Teaching Aids; Reprinted with permission from Hagberg CA, ed., Benumof’s Airway Management, 2nd ed., St. Louis: Mosby; 2007.)

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the soft palate and running along the lateral aspect of the pharynx. Insert a 25-g spinal needle 0.25 cm to 0.5 cm deep at the base of the palatoglossal arch, just lateral to the base of the tongue, and perform an aspiration test. If air is aspirated, the needle has been advanced too deeply (the tip has advanced all the way through the palatoglossal arch) and should be withdrawn until no air can be aspirated; if blood is aspirated, then the needle should be redirected more medially. Inject 2 mL of 1% to 2% lidocaine, and repeat the procedure on the contralateral side.

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24

• Several different landmarks may be used: the greater cornu of the hyoid, the superior cornu of the thyroid, and the thyroid notch. • Technique: Identify the greater cornu of the hyoid and walk a 25 g needle off the cornu of the hyoid bone in an anterior-inferior direction. A slight resistance is felt as the needle is advanced through the thyrohyoid membrane usually at a depth of 1 cm to 2 cm (2–3 mm deep to the hyoid bone). Perform an aspiration test. If air is aspirated, then the needle has passed too deep and entered the pharynx; the needle should be withdrawn until no air is aspirated. If blood is aspirated, then the needle has cannulated either the superior laryngeal artery or vein or has cannulated the carotid artery; the needle should be directed more anteriorly. When satisfactory needle placement is achieved, 2 mL to 3 mL of local anesthetic is injected as the needle is withdrawn. The block is repeated on the opposite side. • Alternatively, identify the superior cornu of the thyroid and walk a 25 g needle off in an anterior-superior direction. Perform an aspiration test and inject the total volume of local anesthetic. • In some patients, the easiest landmark to identify may be the thyroid notch. Palpate the thyroid notch, and trace the upper border of the thyroid cartilage laterally for approximately 2 cm. Pierce the thyrohyoid ligament with a 25 g needle just above the thyroid cartilage at this location and advance the needle in a posterior and cephalad direction to a depth of 1 cm to 2 cm from the skin. Perform an aspiration test and inject the total volume of local anesthetic. Transtracheal Anesthesia (Figs. 2.8 and 2.9): • This block primarily provides anesthesia of the trachea. As a result of the coughing elicited by the block, the local anesthetic injected is nebulized and provides additional anesthesia of the inferior larynx and vocal cords. • Equipment: Tuberculin syringe or a 25 g needle with lidocaine 1% to 2%; 20 g angiocatheter attached to a 5 mL syringe containing 3 mL saline; syringe containing 3 mL to 5 mL of lidocaine 2% to 4%.

Hyoid

Thyroid

Thyrohyoid membrane

Cricothyroid membrane— midline injection Thyroid gland isthmus Trechea

Figure 2.8 Translaryngeal anesthesia, anatomic landmarks. (From Brown D, ed., Atlas of Regional Anesthesia, 2nd ed., Philadelphia: Saunders; 1999.)

(B)

(C)

(D)

Figure 2.9 Translaryngeal anesthesia (midsagittal view of the head and neck). (A) Angiocatheter inserted at the cricothyroid membrane, aimed caudally. Aspiration test performed to verify position of tip of needle in tracheal lumen. (B) Needle is removed from angiocatheter. (C) Syringe containing local anesthetic attached. Aspiration test repeated. (D) Local anesthetic is injected, resulting in coughing and nebulization of the local anesthetic (shaded area). (From University of California, Irvine, Department of Anesthesia: The Retrograde Cookbook; Reprinted with permission from Hagberg CA, ed., Benumof’s Airway Management, 2nd ed., St. Louis: Mosby; 2007.)

• Positioning: Position the patient supine, with the neck in slight extension, if possible. Stand at the side of the patient with the dominant hand closest to the patient. • Technique: Identify the midline of the cricothyroid membrane as the needle insertion site and raise a small skin wheal with local anesthetic using a tuberculin syringe or a 25 g needle. Advance the 20 g angiocatheter with the attached saline-filled syringe through the skin perpendicularly while aspirating. When air is freely aspirated, advance the sheath of the angiocatheter, remove the needle, and attach a syringe containing 3 mL to 5 mL of 2% to 4% lidocaine to the catheter sheath that has been left in place. Confirm the sheath position by aspiration of air, warn the patient to expect vigorous coughing, and rapidly inject the local anesthetic during inspiration. The sheath of the angiocatheter may be left in place until the intubation is complete in case more local anesthetic is needed and to decrease the likelihood of subcutaneous emphysema. Video 2.1 Transtracheal Anesthesia

Tip Transtracheal anesthesia is especially useful when time for a neurologic exam after intubation is desired, such as in the patient with an unstable cervical spine and/or severe cervical stenosis.

25

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(A)

2 Preparation for Awake Intubation

26

Suggested Reading 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 2003;98:1269–1277. Artime C, Sanchez A. Preparation of the patient for awake intubation. In: Hagberg CA, ed. Benumof’s Airway Management. 3rd ed. Philadelphia: Mosby, 2012:243–264. Walsh M, Shorten G. Preparing to perform an awake fiberoptic intubation. Yale J Biol Med 1998;71:537–549. Atkins JH, Mirza N. Anesthetic considerations and surgical caveats for awake airway surgery. Anesthesiol Clin 2010;28:555–575. Stoelting RK, Hillier SC. Anticholinergic drugs. In: Pharmacology and Physiology in Anesthetic Practice. 4th ed. Philadelphia: Lippincott Williams & Wilkins, 2012:266–275. Donlon JV Jr., Doyle DJ, Feldman MA. Anesthesia for eye, ear, nose, and throat surgery. In: Miller RD, ed. Miller’s Anesthesia. 6th ed. Philadelphia: Elsevier Churchill Livingstone, 2005:2527–2556. White PF, Recart Friere A. Ambulatory outpatient anesthesia. In: Miller RD, ed. Miller’s Anesthesia. 6th ed. Philadelphia: Elsevier Churchill Livingstone, 2005:2589–2636. Fukuda K. Intravenous opioid anesthetics. In: Miller RD, ed. Miller’s Anesthesia. 6th ed. Philadelphia: Elsevier Churchill Livingstone, 2005:379–438. In: Miller RD, ed. Miller’s Anesthesia. 6th ed. Philadelphia: Elsevier Churchill Livingstone, 2005:317–378. Strichartz GR, Berde CB. Local anesthetics. In: Miller RD, ed. Miller’s Anesthesia. 6th ed. Philadelphia: Elsevier Churchill Livingstone, 2005:573–604. Simmons ST, Schleich AR. Airway regional anesthesia for awake fiberoptic intubation. Reg Anesth Pain Med 2002;27:180–192 Brown DL. Atlas of Regional Anesthesia. 4th ed. Philadelphia: Saunders, 2010. Kundra P, Kutralam S, Ravishankar M. Local anesthesia for awake fiberoptic nasotracheal intubation. Acta Anaesthesiol Scand 2000;44:511–516.

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Chapter 3

Preoxygenation Strategies and Positioning Tips Henrique Vale, MD and Davide Cattano, MD, PhD

Objectives • Learn how to optimize airway exposure during direct laryngoscopy and other airway management procedures. • Learn the basics of preoxygenation and optimization of oxygen delivery and ventilation.

Introduction This chapter will emphasize the importance of various methods of patient positioning to optimize direct laryngoscopy. Different positions are proposed for different patients and scenarios that can help the anesthesiologist improve visibility when attempting to place an endotracheal tube (ETT). The four most common laryngoscope positions will be discussed: sniffing, ramped, neutral, and beach chair. The importance of preoxygenation and the techniques that provide the longest apnea time before attempting airway instrumentation will also be highlighted in this chapter.

Laryngoscopy Positioning The goal when positioning a patient for direct laryngoscopy is to achieve the best possible alignment of the three airway axes: oral, pharyngeal and laryngeal (see Fig. 3.1).

Tip To reach the best positioning for induction of general anesthesia, the provider should achieve the best alignment of the three airway axes: oral, pharyngeal, and laryngeal.

Sniffing Position In 1936, Ivan Magill first proposed the sniffing position as the optimal position for direct laryngoscopy and described it as someone “drinking a pint of beer” or “sniffing the morning air.” It is

28

(A)

Oral axis (OA)

3 Preoxygenation Strategies

Pharyngeal axis (PA)

Laryngeal axis (LA)

OA

(B) PA LA

PA LA

(C)

OA

Figure 3.1 The three airway axes (A) in the neutral position, (B) with elevation of the head, and (C) with atlanto-occipital extension (the sniffing position). (Reprinted with permission from Miller RD, ed. Miller’s Anesthesia, 6th ed., Philadelphia: Churchill Livingstone: 2004.)

considered the best position for the preparation of a non-obese patient for airway management and endotracheal intubation. It involves the placement of a pillow under the head of the patient to flex the neck and then extend the head, optimizing the alignment of the oral, pharyngeal, and laryngeal axes. This allows for better visualization of the glottis and facilitates the insertion of an ETT with direct laryngoscopy.

Tip During mask ventilation and intubation, the sniffing position is considered the best position for the preparation of a healthy, non-obese patient.

Tip A contraindication to the sniffing position is the risk of aggravation of a cervical spine lesion in patients with suspected or confirmed cervical spine injuries.

Ramped or Head-Elevated Position This position is used in the obese patient to achieve the same alignment of the three axes that is achieved in the non-obese patient with the sniffing position. It is achieved by elevation of the patient’s upper body and head by placing blankets or a specialized device, such as the Troop Elevation Pillow (Mercury Medical; Clearwater, FL) or the RAMP Device (AirPal; Coopersburg, PA), underneath the patient’s torso, bringing the external auditory meatus and the suprasternal notch into horizontal alignment (see Fig. 3.2) Alternatively, the OR table can be used to elevate the patient’s upper body and lower the head, creating a “wedge” that facilitates visualization of the glottis and maximizes upper airway patency. The ramped position improves ventilation of the obese patient by downward displacement of fat and abdominal contents via gravity, diminishing pressure on the diaphragm and decreasing intrathoracic pressure. This reduction of lung restriction reduces work of breathing and increases function residual capacity (FRC), allowing better preoxygenation and granting more time for the anesthesiologist to perform endotracheal intubation with delayed desaturation. Similarly to the sniffing position, the use of this position is contraindicated in patients with known or suspected cervical spine injuries because of the risk of further injury.

Tip In the head-elevated position, the reduction of intrathoracic pressure decreases work of breathing and increases the functional residual capacity, allowing better preoxygenation in obese patients.

Neutral “In-Line” Position When placed in the neutral position, there is no pillow or blanket under the patient’s head or torso. The intent is to keep the head in the most natural position, possibly in-line with the cervical spine, avoiding any degree of extension or flexion of the neck or head. This position is usually reserved for patients with known or suspected unstable cervical spine injuries, when movement of the neck or head can further aggravate the injury. Unfortunately, this position does not provide alignment of the three axes (oral, laryngeal, and pharyngeal) and creates suboptimal conditions for direct laryngoscopy and endotracheal intubation. Chin lift or jaw-thrust may be performed to help the anesthesiologist actually perform the intubation. Alternative airway management techniques, such as video laryngoscopy, fiberoptic

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3 Preoxygenation Strategies

When placing the patient in the sniffing position, the anesthesiologist flexes the lower cervical spine and extends the upper cervical spine and atlanto-occipital joint to optimize exposure of the glottis. Ensuring that the ears are level with the suprasternal notch helps to confirm optimal positioning. This position is contraindicated in patients with known or suspected cervical spine injuries because of the risk of worsening of the injury. Examples include trauma patients or patients with anterior atlanto-axial subluxation, such as in rheumatoid arthritis or Down syndrome.

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3 Preoxygenation Strategies

(A)

(B)

Figure 3.2 A morbidly obese patient placed in (A) a sniffing position and in (B) a head elevation position.

intubation, or retrograde intubation, can also be used to facilitate endotracheal intubation in this position.

Tip The neutral or “in-line” position keeps the head in line with the cervical spine, avoiding any degree of extension or flexion of the neck or head. This position is reserved for patients with suspected or confirmed unstable cervical spine injuries.

Beach Chair Position The beach chair position is achieved by placing the patient in the supine position with the upper body elevated 45°. This position reduces the risk of airway collapse and obstruction, permitting the patient to maintain airway patency during airway instrumentation. In this position, the patient’s head is in-line with the xyphoid process of the anesthesiologist, and often, the anesthesiologist will need a stepstool to facilitate mask ventilation and direct laryngoscopy. This position is best for fiberoptic intubation, especially if the provider approaches the patient from the front and has an assistant pulling the tongue and/or performing a jaw thrust. An important consideration when using this position is that the degree of elevation may reduce the venous return to the heart and lower blood pressure. Some shoulder surgeries are performed in this position for surgical exposure and less bleeding. However, cases have been reported of severe brain damage, stroke, visual loss, and death resulting from low cerebral perfusion associated with this position. The primary recommendation when using this position is to measure the blood pressure at the level of the heart to avoid discrepancies.

Preoxygenation Preoxygenation is considered the first step for every patient requiring any type of airway management. This technique is also called denitrogenation because of the exchange of nitrogen (N2) in the lungs for oxygen (O2). The goal of preoxygenation is to prolong the apnea time, which is the length of time after the onset of apnea until a patient begins to desaturate, to allow sufficient time for airway management. To achieve adequate preoxygenation, studies have shown that the end tidal oxygen fraction should reach levels above 90%. Because air is composed of 21% O2, 78% N2, and 0.9% of a mix of argon (Ar) and carbon dioxide (CO2), it is easy to understand the impact of exchanging this 78% of N2 for O2 (see Fig. 3.3).

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Nitrogen

21%

Oxygen Carbon Dioxide and Argon 0.9% Figure 3.3 Air is composed of nitrogen, oxygen, and a mix of carbon dioxide and argon.

Tip Preoxygenation is considered the first step for every patient requiring airway management.

Physiology of Preoxygenation In adults breathing room air, the amount of oxygen in the body is approximately 1550 mL, which is distributed as O2 bound to hemoglobin (850 mL), O2 that remains in the lungs (480 mL), and O2 that is dissolved in blood (220 mL). Hemoglobin-bound O2 is not readily available because of the high affinity of O2 for hemoglobin, and the O2 dissolved in the blood is such a small quantity that the O2 in the lungs is the only real source of O2 in the body. In the setting of apnea, this amount is insufficient to maintain life for more than a few minutes. Oxygen consumption (VO2) in an adult can be estimated based on a patient’s weight in kilograms using the formula VO2 = 10(weight)¾. This calculates to approximately 3 mL⋅kg−1⋅min−1 or 200 mL/min to 250 mL/min. The FRC is the volume of air present in the lungs at the end of passive expiration. To calculate the amount of oxygen available in the lungs during periods of apnea, the FRC volume is multiplied by the inspiratory fraction of O2 (FiO2). A healthy adult will have an FRC of 2300 mL and a room air FiO2 of 21%. Thus, the amount of oxygen available would be approximately 483 mL of pure O2. If the VO2 for this same adult is 200 mL/min to 250 mL/min, the allowable apnea time until the onset of desaturation is less than 2 minutes. If this same adult breathes 100% O2, however, the amount of O2 available would be 2300 ml (FRC of 2300 mL multiplied by a FiO2 of 100%), which would allow for as much as 10 minutes of apnea before the start of desaturation. Studies have shown that the minimum expiratory fraction of oxygen (FEO2) to ample apnea time to allow for airway instrumentation is 80%.

Tip A healthy adult fully preoxygenated with 100% O2 will have approximately 2300 mL of oxygen in the lungs, which will assure approximately 10 minutes of apnea before desaturation.

Techniques for Preoxygenation Methods for preoxygenation before induction of anesthesia can be divided into slow and fast techniques. It is important to ensure that there is no leak in the circuit and/or anesthesia machine, that 100% O2 is provided, and that rebreathing does not occur.

3 Preoxygenation Strategies

78%

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For either technique, the position of the patient is important and can make a meaningful impact on apnea time. The induction of general anesthesia decreases the FRC by 20% in a non-obese patient and by up to 50% in an obese patient. Placing patients in a supine position will result in greater decreases in FRC as compared to patients in the heads up or sitting position. Patients who are obese, pregnant, or who have restrictive lung disease have an even lower FRC compared to healthy people. Low FRC diminishes the efficacy of preoxygenation and decreases the time period preceding desaturation. One study measuring time to desaturation after preoxygenation showed an average apnea time of 6.1 minutes in lean patients compared to 2.7 minutes in the morbidly obese. Thus, it is advantageous to preoxygenate obese patients in the upright position to increase FRC and increase the apnea time. Pregnant patients showed no differences related to position and apnea time.

Slow Technique The slow preoxygenation technique is performed successfully by delivering 100% O2 via a facemask with a perfect seal and asking the patient to breathe at normal tidal volumes for approximately 3 minutes. Within 3 minutes, the patient’s FEO2 usually reaches levels greater than 90%, ensuring a maximal apnea time during airway management. When a perfect seal is difficult to achieve (e.g., because of the presence of a beard or a lack of dentition), the practitioner can attempt to create a better seal using a two-handed technique. The anesthesia machine can be used to deliver continuous positive airway pressure (CPAP) or pressure support ventilation (PSV) to augment tidal volumes and improve the quality of preoxygenation.

Fast Technique The preoxygenation fast technique can be performed by providing 100% O2 by face mask with a perfect seal and asking the patient to take vital capacity breaths. Studies have shown that it is necessary to take approximately eight vital capacity breaths in 1 minute to be able to reach a FEO2 greater than 90%. Some studies support four deep breaths in 30 seconds to provide adequate preoxygenation. This technique is useful during emergencies but requires patient cooperation and can promote mild hypocapnia.

Preoxygenation Techniques Without a Face Mask Different techniques for preoxygenation are required when a facemask cannot be applied. In the claustrophobic patient or when it is impossible to maintain a perfect seal on the face mask (e.g., because of a large beard or the presence of a nasogastric tube), an alternative technique may be attempted by disconnecting the mask from the circuit and asking the patient to breath around the 15 mm circuit connector. Studies have demonstrated that administering oxygen via a nasal cannula after induction prolongs the apnea time even when respiratory movements are not occurring. This phenomenon, known as apneic oxygenation, is possible because the exchange of O2 and CO2 in the alveoli creates a diffusion gradient from the pharynx (containing a higher concentration of oxygen from the nasal cannula) to a lower concentration of oxygen in the alveoli. Another option is to use high oxygen flow rates (30–48 L/min) that permit adequate preoxygenation, even through a loose-fitting mask. This technique cannot be used in the anesthesia setting because anesthesia machines are not able to provide such a high flow.

Morbidly Obese Patient With Obstructive Sleep Apnea The morbidly obese patient with obstructive sleep apnea (OSA) requires special attention during preoxygenation because this population has increased oxygen consumption and a greatly

Tip Morbidly obese patients benefit from the head-elevated position during preoxygenation and from nasopharyngeal oxygen delivery after induction. BiPAP is useful for critically ill patients with severe atelectasis, intrapulmonary shunt, and increased A-a gradient.

Extubation Techniques and Oxygen Delivery An important aspect of airway management and most important regarding morbidity and mortality is a safe extubation. In both cases in which the airway is challenging, as well as routine cases, extubation should proceed smoothly, should rely on complete recovery from muscle relaxation, and should avoid increases in intrathoracic pressure from retching or bucking, especially in situations where an increase in venous pressure or intracranial pressure could be detrimental. When extubation is performed under deep anesthesia, one technique to optimize oxygen delivery is to utilize an oral airway and leave the ETT immediately extraglottic. Additionally, an ETT can be substituted via the Bailey maneuver, leaving the LMA in place. With these techniques, the continuous monitoring of ventilation, patient rate, effort and CO2 is possible, while O2 is delivered easily through the laryngeal inlet. In morbidly obese patients, because of a high incidence of OSA, it is recommended to extubate patients fully awake to avoid airway obstruction and desaturation. Also, higher intra-abdominal pressure increases the risk of aspiration if these patients are not awake enough to protect their airway.

Final Considerations A SpO2 of 100% does not necessarily mean that a patient is preoxygenated, because hemoglobin reaches 100% saturation with O2 concentrations slightly above room air. Possible, but rare, side effects from preoxygenation include increased risk of atelectasis (most commonly in the obese patient), increased systemic vascular resistance, decreased heart rate and cardiac output, and hypocapnia (which decreases cerebral blood flow and increases the required dose of anesthetic induction agent). Nevertheless, preoxygenation should not be avoided simply to prevent these side effects. In elderly patients, due to the difficulty of obtaining consistent cooperation and the potential for leak between the mask and face (due to the absence of teeth and loss of tone of the jaw and

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reduced FRC. The airway anatomy of an obese patient can result in difficult airway management largely because of a low thyromental distance and a neck circumference greater than 17 inches, requiring more time for the intubation. Preoxygenation in the obese patient is recommended to be performed in a head-up position. The use of a Boussignac CPAP mask is advocated by some because CPAP would increase the FRC, but studies have shown that this increase is not significant and that the FRC returns to pre-CPAP values once the mask is disconnected from the patient. Apneic oxygenation via nasopharyngeal oxygen delivery following preoxygenation increases the apnea time in morbidly obese patients. Unfortunately, this technique may not be effective in critically ill patients because of atelectasis, increased intrapulmonary shunt, and a high A-a gradient. For these patients, bilevel positive airway pressure (BiPAP) is recommended because it promotes alveolar recruitment and, more specifically, decreases the intrapulmonary shunt and A-a gradient. Obese patients are more prone to develop atelectasis, thus a high FiO2 for prolonged periods of time is contraindicated because of the risk of further increases via absorption atelectasis.

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cheek muscles), the slow technique is more effective than the fast technique. Because of the decreased minute ventilation observed in this population, the patient may require more than 3 minutes to reach adequate FEO2.

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Suggested Readings 1. Weingart SD, Levitan RM. Preoxygenation and prevention of desaturation during emergency airway management. Ann Emerg Med. 2012;59(3):165–175. 2. Bein B, Scholz J. Anaesthesia for adults undergoing non-bariatric surgery. Best Pract Res Clin Anaesthesiol. 2011;25(1):37–51. 3. Leykin Y, Pellis T, Del Mestro E, Marzano B, Fanti G, Brodsky JB. Anesthetic management of morbidly obese and super-morbidly obese patients undergoing bariatric operations: hospital course and outcomes. Obes Surg. 2006;16(12):1563–1569. 4. Mort TC. Preoxygenation in critically ill patients requiring emergency tracheal intubation. Crit Care Med. 2005;33(11):2672–2675. 5. Cattano D, Cavallone L. Airway management and patient positioning: a clinical perspective. Anesthesiology News 2011;37(8):17–23.

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Chapter 4

Mask Ventilation

William H. Daily, MD

Objectives • • • • •

Assess patient features and airway history that would predict success of mask ventilation. Introduce devices used for mask ventilation. Discuss mask ventilation: one handed versus two handed. Provide detailed instructions and tips to ensure successful mask ventilation. Outline rescue maneuvers for difficult/impossible mask ventilation.

Introduction Mask ventilation is an essential skill for health-care workers, especially those involved with airway management. It can provide adequate oxygenation and ventilation for the patient who is unable to support their own respirations. With a moderate amount of instruction, most health-care providers can and should be able to perform this ventilatory technique.

Patient Airway Assessment Evaluation of the patient’s physical features and obtaining a history of a difficult airway are critical steps prior to performing airway management. It has been stated that “the single most reliable predictor of a difficult airway is a history of a difficult airway.” Physical features noted in patients with difficult mask ventilation include beard, obesity, edentulousness, history of obstructive sleep apnea, enlarged jaw, thick tongue, poor atlanto-occipital extension, as well as facial burns and deformities. Poor mandibular protrusion is not a risk factor for difficult mask ventilation, but it has been associated with difficult intubation. Physical features noted in patients with impossible mask ventilation include beard, neck radiation changes, male sex, sleep apnea, and Mallampati III or IV.

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Predictors of Difficult Mask Ventilation Tips • A history of a difficult airway is the single most reliable predictor. • Inability to protrude the lower incisors over the upper incisors is associated with difficult laryngoscopy but not difficult mask ventilation. • Difficult mask ventilation predictors: beard, obesity, edentulousness, history of obstructive sleep apnea, enlarged jaw, thick tongue, poor atlanto-occipital extension, history of facial burns. • Impossible mask ventilation predictors: (in addition to predictors of difficult mask ventilation) neck radiation, Mallampati III or IV, male gender.

Mask Ventilation Devices The two main types of face masks are the older style, black rubber reusable masks and the newer, clear plastic, disposable masks (Fig. 4.1). In general, the clear plastic mask is more comfortable for the awake patient. The three main components of the mask include: (1) the body or main component of the mask, which if clear allows observation of the exhaled moisture or secretions during mask ventilation; (2) the seal, which is achieved with the mask covering the patient’s mouth and nose, and (3) the connector, which allows the anesthesia circuit or AMBU bag to be attached to the mask. The Rendell-Baker-Soucek Mask® (Rusch Medical, Teleflex, Research Triangle Park, NC) is triangular in shape and is designed for the pediatric population as it is associated with a small dead space. The ErgoMask® (King Systems Airway, Noblesville, IN) is a recently developed mask that has a special finger/thumb contoured grip to facilitate one-handed mask ventilation (Fig. 4.2). The ErgoMask® improves control of mask seal and facilitates proper chin lift to assist with opening the airway. Its ventilation port is off-center, which enables use with small hands. Another specialized mask, the Endoscopy MaskTM, (VBM Medizintechnik GmbH, Sulz am Neckar, Germany) can be utilized for procedures, such as upper endoscopy or fiberoptic bronchoscopy, as these techniques can be performed through the mask without any interruption of ventilation (Fig. 4.3). Finally, utilization of scented masks may increase acceptance by the pediatric population during mask induction of general anesthesia. Utilization of an oral airway is recommended if initial attempts at mask ventilation are suboptimal. The oral airway has several variants, but they all follow a basic curved design to allow the tongue and epiglottis to be lifted away from the posterior pharyngeal wall during mask ventilation. To avoid coughing or gagging, the patient’s pharyngeal and laryngeal reflexes should be suppressed prior to their use. Utilization of a nasopharyngeal airway is another method of assisting difficult mask ventilation. Lubrication of the nasal airway should be performed prior to insertion. It is then placed into the larger nostril and gently advanced posteriorly, in line with the nasal passage, until it is past the base of the tongue but still above the epiglottis. If resistance is met during insertion, then the nasal airway should be removed; a smaller size nasal airway should be selected or the other nostril used for the subsequent attempt. If mask ventilation is difficult, then application of an endotracheal tube (ETT) connector to a nasal airway and connecting this to the anesthesia circuit may aid in ventilation of a patient. With this method, it is necessary to occlude the opposite nostril, as well as the patient’s mouth, to achieve adequate ventilation.

One-Handed Mask Ventilation The face mask should be attached to the anesthesia circuit (or AMBU bag) with high-flow (8–10 L/min) oxygen. In the patient undergoing anesthesia, pre-oxygenation is undertaken prior

Figure 4.1 A standard, black rubber, reusable face mask and a standard, clear plastic, disposable face mask.

Figure 4.2 Side-by-side comparison of the ErgoMask® (left) and a standard face mask (right). (Reprinted with permission from Bauman EB, et al. An evaluation of bag-valve-mask ventilation using an ergonomically designed facemask among novice users: A simulation-based pilot study. Resuscitation 2010;81(9):1161–1165.)

to administration of anesthetizing drugs. The mask is held with the left hand. To create a seal, the mask is placed snugly over the bridge of the nose and on the chin. The thumb and index finger are held on either side of the connector. Care must be taken to avoid contact with the eyes. The other fingers can be placed on the mandible with the little finger lifting the angle of the mandible. Alternatively, the practitioner’s hand may be centered over the mask and the chin lifted. This elevation of the mandible assists in opening the airway. Care must be taken to avoid applying too much pressure, as this could compromise the airway. Following the loss of airway reflexes, the right hand is used to ventilate the patient by squeezing the reservoir bag. If a leak around the mask is observed, then counteractive pressure should be applied to the right side of the mask.

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Figure 4.3. The Endoscopy MaskTM. (Copyright image provided courtesy of VBM Medizintechnik GmbH, Sulz am Neckar, Germany)

Exhalation of carbon dioxide should be observed via capnography or with the Easy Cap® (Nellcor, Boulder, CO) when the AMBU bag is used.

Two-Handed Mask Ventilation Following the preparation described above regarding oxygen supply, equipment, and drugs, the use of one-handed mask ventilation should allow ventilation of the majority of patients. If one-handed mask ventilation is inadequate, then two-handed mask ventilation can be performed, which requires an assistant to provide the actual ventilation, if the patient is not spontaneously breathing. It should be utilized if attempts at single-handed ventilation fail. In the two-handed mask ventilation technique, the thumb is placed on the side of the mask and the index finger is placed under the angle of the mandible. Elevation of the mandible and extension of the head should allow for a patent airway to be obtained. Similarly to one-handed mask ventilation, exhalation of carbon dioxide should be observed via capnography or with the Easy Cap® when the AMBU bag is used.

Mask Ventilation Tips: • Elevation of the angle of the mandible along with a good mask seal are the two most important features to ensure adequate mask ventilation. This may be accomplished with the last two fingers elevating the mandible into the mask, while extending the neck, if not contraindicated. • One-handed mask ventilation requires the mask to be secured with the index finger securing the mask near the chin and the thumb holding the mask near the bridge of the nose. Two-handed mask ventilation utilizes a thumb securing each side of the mask. • Placement of an oral or nasal airway may assist with mask ventilation. In addition, changing the position of the head and/or jaw may help improve ventilation.

Rescue Maneuvers

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Video 4.1

Mask Ventilation Techniques

Summary Mask ventilation is an important skill to be utilized whenever airway support is needed. Factors to improve successful mask ventilation include airway assessment, presence of necessary supplies including oxygen and airway masks, as well as oral or nasal airways. Elevation of the angle of the mandible is as important as a tight mask fit to ensure adequate ventilation. Utilization of one- or two-handed mask ventilation may be needed, depending on the skill of the practitioner or the patient’s anatomy. Rescue supplies should be available if mask ventilation is inadequate.

Suggested Reading American Society of Anesthesiologists Task Force of Management of the Difficult Airway. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologist Task Force on Management of the Difficult Airway. Anesthesiology 2003; 98(5):1269–1277. Matten EC, Shear T, Vender JS. Nonintubation management of the airway: airway maneuvers and mask ventilation. In: Hagberg CA, ed. Benumof’s Airway Management 3rd ed. Philadelphia, PA: Mosby Elsevier; 2012:340–345. Dorsch JA & Dorsch SE. Face masks and airways. In: Understanding Anesthesia Equipment 5th ed, Philadelphia, PA: Lippincott Williams and Wilkins; 2008:444–450. Langeron O, Masso E, Huraux C, et al. Prediction of difficult mask ventilation. Anesthesiology 2000;92(5):1229–1236. Kheterpal S, Martin L, Shanks A, & Tremper K. Prediction and outcomes of impossible mask ventilation: a review of 50,000 anesthetics. Anesthesiology 2009;110(4):891–897.

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If one- or two-handed mask ventilation is unsuccessful in obtaining adequate ventilation, then the provider should call for assistance and place either an oral or nasal airway, as previously described. Changing the position of the head and/or mandible may improve ventilation. Additionally, a forceful mandibular lift is a helpful maneuver. Further efforts to place either a laryngeal mask airway (LMA) or ETT may be attempted, in accordance with the ASA difficult airway algorithm.

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Chapter 5

Nasotracheal Intubation

William H. Daily, MD

Objectives • • • • • •

Discuss indications for nasotracheal intubation. Explain advantages and disadvantages of nasotracheal intubation. Describe preparation for nasotracheal intubation. Describe special equipment needed for nasotracheal intubation. Provide guidelines for determining whether awake versus asleep intubation is indicated. Outline rescue maneuvers if unable to successfully perform nasotracheal intubation.

Introduction Nasotracheal intubation is indicated for operative procedures involving the oral cavity and the face when an oral endotracheal tube (ETT) would block free access to the operative field. Numerous advantages have been described for the patient with a nasotracheal tube, such as improved tolerance and inability of the patient to bite the ETT. Preparation of the nasopharynx prior to intubation involves utilization of vasoconstrictive agents and water-soluble lubricants. Numerous special items are needed for the safe placement of the nasal ETT, including but not limited to nasal trumpets, Magill forceps and a capable assistant. Determination of awake versus asleep intubation is influenced by multiple factors, including NPO status and an airway assessment. In the event of inability to perform nasal intubation, a plan for either oral intubation or surgical airway must be readily available.

Indications for Nasotracheal Intubation Nasotracheal intubation is indicated for operative procedures involving the oral cavity or face when an oral ETT would hinder access to the operative field. In addition, temporomandibular joint limitation or the presence of a mandible fracture might preclude oral intubation. Other indications include cervical spine instability, the presence of intra-oral lesions or other intra-oral pathology.

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On the other hand, nasotracheal intubation should be avoided if severe coagulopathy, intranasal abscess, polyps or other significant masses are present. Although a skull base fracture has been previously listed as a contraindication, reports have described successful fiberoptic nasotracheal intubation in these patients.

Advantages and Disadvantages of Nasotracheal Intubation There are several advantages to nasotracheal intubation, including increased tolerance to the ETT, decreased incidence of biting, and, therefore, occluding the ETT. In the awake patient, nasotracheal intubation bypasses the gag reflex; therefore, it is usually better tolerated and requires less sedation. Disadvantages associated with nasotracheal intubation include longer time and greater difficulty of intubation, use of a smaller sized ETT with resultant increased airway pressure, and the possibility of bleeding. Concerns over sinusitis and bacteremia have also been raised with nasotracheal intubation.

Preparation for Nasotracheal Intubation The nose should be assessed pre-operatively for any signs of obstruction, including polyps or foreign bodies. The patient may be able to inform the practitioner regarding which naris provides better airflow. If no difference is evident, it is best to prepare the right naris, as the bevel of the nasotracheal tube passes through the glottis more easily when introduced via the right naris. Interestingly, determination of which nostril is best for intubation by obstruction of each nostril and listening for the best airflow from the contralateral side has not been shown to correlate with nasal abnormalities. Use of a vasoconstrictive agent should be applied to the both nostrils prior to placement of a nasal airway. Preparation continues by placement of a nasal airway that has been lubricated with lidocaine gel, if available. The ETT should be one size smaller than the size normally used for an oral intubation. The ETT should be warmed prior to insertion to allow it to be softer and more compliant. This can be easily accomplished by placing it in a liter bottle of warm irrigating solution or water. The ETT should also be well lubricated with a lidocaine gel, immediately prior to insertion. It can also be curled into a circle by inserting the distal end into the proximal end, so that the ETT has the memory of a curvature when used for intubation.

Equipment Needed for Nasotracheal Intubation In addition to the nasal airways mentioned above, it is important to have water-soluble lubricant, vasoconstrictive nasal spray, a liter bottle of warm irrigating solution or water, Magill forceps, and smaller sized ETTs. Additional aids have been described to aid in nasotracheal intubation. Two of the more common are listed here. 1. The BAAM Whistle® (Beck Airway Airflow Monitor, Great Plains Ballistics, Lubbock, TX) is a device that consists of a plastic whistle that fits on the proximal end of the ETT (Fig. 5.1). It has a 2 mm opening that produces a loud whistle when air passes through it in a spontaneously breathing patient. Proximity to the tracheal air column determines the loudness of the sound. Placement of the ETT into the esophagus will result in cessation of the sound. This intubation aid is used primarily for blind nasotracheal intubation. 2. An alternative to blind intubation using the BAAM is to attach a capnography line to the proximal end of the ETT as it is advanced. The carbon dioxide trace will continue to display as the ETT goes toward and enters the glottis when the patient is breathing spontaneously or when ventilated by the practitioner. Introduction into the esophagus may exhibit carbon dioxide if there has been entrainment of exhaled gas into the stomach or recent consumption of carbonated beverages.

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Figure 5.1 BAAM Whistle® (Great Plains Ballistics, Lubbock, TX).

Awake versus Asleep Intubation The determining factors as to whether to secure a patient’s airway following induction of general anesthesia or awake are multifactorial. Consideration of many factors, such as a cervical spine injury, airway assessment, NPO status, and whether a patient will be able to cooperate with the performance of an awake intubation, must be determined. If an awake intubation (AI) is indicated, several steps are required (see Chapters 2 and 9 for further detail). 1. Patient preparation with a detailed pre-operative visit informing the patient of the need for AI. 2. Utilization of an antisialagogue approximately 20 minutes prior to the start of AI. 3. Titrated sedation individualized to the patient, maintaining meaningful contact at all times. 4. Administration of vasoconstrictive agent to both nares. 5. Airway anesthesia of the nasal and laryngotracheal mucosa. If AI is chosen for nasal intubation, the use of a fiberoptic bronchoscope (FOB) to facilitate intubation is preferable. The FOB should be inserted into the more patent nostril, which has been properly prepared. The practitioner can either choose to place a well-lubricated, pre-warmed ETT through the appropriate nostril first, or the FOB can be loaded with a similarly prepared ETT and advanced through the nares after the FOB has been directed into the trachea. Advancement of the ETT into the nostril first has the advantage of providing a pathway free of secretions for the FOB and early determination of a tight nasal passage. Disadvantages of this technique include increased chance of airway trauma and possible bleeding. On the other hand, if the FOB is placed into the nostril first, there is a chance that advancement of the ETT may not be possible, although the FOB is located in the trachea. An alternative technique to either of these procedures is to place the FOB in one nostril while passing the ETT through the opposite nostril. The FOB simply is used for visualization as the ETT is guided through the glottis. Video 5.1 Fiberoptic-assisted nasotracheal intubation

If the decision is made to proceed with nasotracheal intubation after induction of general anesthesia, then fiberoptic bronchoscopy, direct laryngoscopy, or video laryngoscopy can be utilized.

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Figure 5.2 Magill forceps.

The above steps regarding preparation (vasoconstrictive nasal spray, placement of nasal airway, etc.) are performed and placement of the nasotracheal tube follows. An ETT one size smaller than normal should be chosen, and as it is advanced, the tip should be directed medially and the bevel laterally. This is to ensure that the tip of the tube does not cause trauma to the nasal turbinate. Passage of the ETT should be performed in a gentle fashion in a posterior, caudad, medially directed movement until it enters the oropharynx. If resistance is met, then attempt to withdraw, rotate, and re-insert the ETT. Once the ETT enters the posterior pharynx, it can be guided between the vocal cords by use of a Magill forceps (Fig. 5.2) with concurrent direct of video laryngoscopy. An assistant is needed to slowly advance the ETT under the direction of the individual viewing the vocal cords. Once tracheal intubation has been confirmed by capnography, the ETT may be secured with either adhesive tape or a suture through the nasal septum and wrapped tightly around the ETT. Video 5.2 Video laryngoscope-assisted nasotracheal intubation

Nasotracheal Intubation Tips • Consider nasotracheal intubation when use of an oral ETT would hinder visualization of the operative field or if the mouth is going to be wired closed. • Avoid nasotracheal intubation if intranasal abscess, nasal polyps, or severe coagulopathy are present. • Apply a vasoconstrictive agent to the nasal mucosa and then place a water-soluble lubricant or lidocaine gel on the nasal trumpet and the ETT. • The ETT used should be one size smaller than normally used for orotracheal intubation. • If time permits, it is best to soften the ETT by placing it in a warm bottle of irrigating solution or water. • Never force advancement of the ETT. If resistance is met, then consider using a smaller size ETT, rotating the ETT or using the other nostril.

Rescue Maneuvers When nasal intubation is necessary but unsuccessful, alternative intubation techniques should be considered if the patient is unable to maintain their own airway, including the possibility of a surgical airway.

Summary Nasotracheal intubation is required when the operative procedure involves the oral cavity and an oral ETT would block access to the operative field or the jaw is going to be wired shut following the procedure. Successful nasotracheal intubation includes preparation of the desired nares with vasoconstrictive agents, as well as placement of nasal airways. Special equipment includes Magill forceps and the presence of a capable assistant. Fiberoptic intubation should always be considered if standard techniques are not successful. Additionally, blind nasotracheal techniques such as blind intubation or lightwand intubation may be considered.

Suggested Reading Berry JM, Harvey S . Laryngoscopic Orotracheal and Nasotracheal Intubation. In: Hagberg CA, ed. Benumof’s Airway Management, 3rd ed. Philadelphia, PA: Mosby Elsevier; 2012:346–358. Dorsch JA, Dorsch SE. Tracheal Tubes and Associated Equipment. In: Understanding Anesthesia Equipment, 5th ed., Philadelphia, PA: Lippincott Williams and Wilkins; 2008:585–587.

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45 • If not contraindicated, small movements of either the head or neck or pressure on the thyroid cartilage may facilitate tracheal intubation. • Specific problems associated with prolonged nasal intubation include sinusitis and pressure necrosis of the nostril. • If visualization via the FOB is obscured by either bleeding or secretions, then consideration can be made for a blind nasotracheal intubation technique, such as blind nasal or lightwand-guided intubation.

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Chapter 6

Supraglottic Airway Devices

William H. Daily, MD

Objectives • Discuss advantages and disadvantages of the supraglottic airway devices. • Describe the different types of supraglottic airway devices. • Describe the use of intubating supraglottic airway devices.

Introduction The use of supraglottic airway devices (SADs) has increased dramatically over the last 25 years. This movement was greatly influenced by the development of the Laryngeal Mask AirwayTM (LMA) by Dr. Archie Brain in the early 1980s. The invention of the LMA has been described as the single most important improvement in airway management over the last 50 years. Since its initial development, there have been multiple variations and improvements of the traditional classic LMA. One of the most useful developments is use of the LMA as a conduit for endotracheal intubation. Fiberoptic intubation through SADs is an important step in the management of unexpected difficult ventilation and/or intubation in both children and adults.

Advantages and Disadvantages of Supraglottic Airway Devices The LMA and other similar devices have many advantages for airway management. First, education and instruction in the placement of these devices can be accomplished in a relatively short period of time for most health-care professionals. Their relative low cost makes them easily obtainable by many facilities and for use both in and out of the operating room setting. In the anesthetized patient, a lower level of anesthesia is required as compared to endotracheal intubation, allowing for a more rapid emergence. Notably, the LMA can be used as either a bridge to intubation or extubation. The LMA has shown its effectiveness as a rescue device for the failed airway and is now in the American Society of Anesthesiologists (ASA) Difficult Airway Algorithm, as well as the American Heart Association’s and European Resuscitative Council’s Guidelines.

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Use of the LMA or other supraglottic devices is contraindicated if complete glottic or supraglottic obstruction is noted. Also, the risk of aspiration is a relative contraindication to its use, and caution should be utilized in these patients at risk for aspiration. For patients with extremely limited mouth opening or neck extension, the use of these devices is severely cautioned against. Obtaining a proper seal may be difficult after the device is placed. Finally, there is no protection against laryngospasm.

Insertion Techniques of Supraglottic Airway Devices The LMA ClassicTM (LMA North America, San Diego, CA) and now the UniqueTM (disposable LMA) are the most widely used supraglottic ventilatory devices (Figs. 6.1 and 6.2). It is listed in the ASA Difficult Airway Algorithm as an airway ventilatory device or as a conduit for fiberoptic intubation in five different locations. Proper insertion of the LMA is mandatory for successful use of the device. Deflation of the cuff prior to placement allows for proper placement. Application of a water-soluble lubricant to the dorsal surface and tip of the LMA prior to insertion aids with ease of insertion. With the aid of the index finger, at the junction between the mask and the shaft of the LMA, the LMA should be inserted along the hard palate directed in a cranio-posterior direction. In the awake patient, this motion imitates the tongue during swallowing. Using the nondominant hand to provide a proper opening of the oropharyngeal angle by head extension and neck flexion

Figure 6.1 LMA ClassicTM. (Copyright image provided courtesy of LMA North America, San Diego, CA.)

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Figure 6.2 LMA Unique™.

is another important action. Also, the jaw may be lifted by the nondominant hand to aid insertion. Following proper placement of the LMA, inflation of the cuff is performed and the LMA is secured. The LMA may block the esophagus depending on its position in the hypopharynx. Video 6.1 LMA Insertion Techniques

If the LMA is going to be used as a conduit for endotracheal intubation, then there are some technical considerations of the length and size of tracheal tubes in relations to dimensions of some SADs that should be taken into account (see Table 6.1). The size of the LMA lumen limits the size of the endotracheal tube (ETT) that can be passed through the device and into the trachea. A size 6.0 mm internal diameter (ID) ETT can be passed through a size 3 and 4 LMA, and a size 7.0 mm ID through a size 5 LMA. Because a 6.0 ETT is only 28 cm in length, and projects only a short distance into the trachea, more appropriate ETTs to consider include a size 6.0 nasal RAE® (34 cm in length) and a size 6.0 microlaryngeal tube, which is 32 cm in length. An updated version of the reusable LMA, the LMA Classic Excel™ has several features that have added benefit (Fig. 6.3). An Epiglottic Elevating Bar (EEB), a removable airway connector, and an increased angle between the airway tube and the laryngeal cuff are designed to aid intubation. The soft silicone cuff reduces the risk of throat irritation, and the entire device is reusable up to 60 times, providing greater cost effectiveness than the LMA Classic™. The LMA ProSealTM (LMA North America, San Diego, CA) has a second port that opens in the distal tip of the mask (Fig. 6.4), which, when properly positioned, lies against the upper esophageal sphincter (UES). A standard gastric tube (size 16 Fr or smaller) can be placed via this port, if needed to suction the stomach. The ProSeal LMA also allows detection of inadequate placement if the distal port is not at the UES, as airway gas will be displaced via the drain port. The ProSeal cuff must not be overinflated (>60 cm H2O), as this can cause herniation of the gastric port toward the glottis, which can cause blockage of the drainage tube and airway compromise. The ProSeal also has a built-in bite block. The presence of a second seal allows positive pressure ventilation to be performed with less likelihood of gastric insufflation. The LMA Supreme™ is a disposable version of the ProSeal with similar features (Fig. 6.5).

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Table 6.1 Relevant Dimensions of Various Supraglottic Airways

6 Supraglottic Airway Devices

LMA ClassicTM LMA UniqueTM

AirQTM

AuraStraightTM AuraOnceTM

Supraglottic airway size

3

4

5

3

4

5

2.5 3.5

4.5

3

4

5

3

4

5

Maximum internal diameter of the ETT (mm)

6

6

7

6

6

7

6.5 7.5

8.5

6

6

7

5.5 6

7

20 20 22 Length of the airway tube of the supraglottic airway* (cm)

20 20 22

16

18

20

18 18 20

17

19 22

30 30 33

30 30 33

26

28

32

28 28 31

27

29 33

Minimum length of the ETT** (cm)

LMA = laryngeal mask airway * Distance between the upper end of the 15 mm connector and the mask aperture. These measures may differ from data in the corresponding instruction manuals. For the air-QTM, the distance listed is from the top of the tube with the connector removed to the mask aperture. ** Minimum ETT length is calculated as the sum of length of the airway tube and 10 cm (5.5 mm or 6.5 mm ETT) or 11 cm (7 mm ETT). The latter is the sum of distance between the mask aperture and the vocal cords and the distance between the upper border of the ETT cuff and the ETT tip.

Figure 6.3 LMA Classic Excel™. (Copyright image provided courtesy of LMA North America, San Diego, CA.)

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Figure 6.4 LMA ProSeal™.

Figure 6.5 LMA Supreme™. (Copyright image provided courtesy of LMA North America, San Diego, CA)

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Laryngeal Mask Airway Tips • The LMA is effective as a rescue device for a failed airway (ventilation and/or nasal intubation), but use of an LMA is contraindicated if complete glottic or subglottic obstruction is present. • There is a risk of regurgitation/aspiration with the use of a supraglottic airway device. Proper patient selection is imperative. • Select the most appropriate LMA for the surgical procedure. (e.g., a flexible LMA may be preferred for nasal, facial, plastic, and ophthalmologic surgery). • Proper LMA insertion requires application of a water-based lubricant to its dorsal surface, followed by LMA insertion into the oral cavity along the hard palate using a digital insertion technique. Following LMA placement, the cuff may be inflated and position verified by noting adequate ventilation. • Secure the LMA appropriately to prevent dislodgement. • Provide adequate depth of anesthesia, especially when a patient is not paralyzed. In the event of an inadequate seal or ventilation, slight repositioning by 3 cm to 5 cm LMA withdrawal may remedy the situation. If a proper seal is still not obtained, then use of a smaller size LMA may solve the problem. • If cricoid pressure is necessary, it may require its temporary interruption for proper LMA placement, followed by reapplication if ventilation is adequate. • Use of the LMA as a conduit for intubation requires use of size 6.0 mm ETT with a size 3 or 4 LMA. The same size nasal Rae or microlaryngeal tube may be considered to provide adequate length. If a size 5 LMA is in place, a size 7.0 mm ETT may be used. The Combitube® (Covidien, Mansfield, MA) is a uniquely designed supraglottic device (Fig. 6.6) developed by an internist, Dr. Michael Frass. It has been used extensively in emergency situations, as well as during routine surgery. Two different sizes are available: a small adult size (37 Fr, Combitube SA) for use in patients 120 cm to 130 cm in height and a 41 Fr size for use in taller patients. It has two cuffs; one cuff is at the distal (esophageal) end and a second (oropharyngeal) cuff is composed of latex and is located at the middle portion of the tube. When tracheal placement occurs, insufflation of only the distal cuff is necessary. Almost 98% of the time, esophageal placement of the device occurs, in which ventilation would be performed via the #1 (esophageal), blue proximal lumen, which is longer than its counterpart. Its distal end is closed and it has eight small perforations, to allow oxygenation and ventilation. When the device is placed into the trachea, ventilation should occur via the #2 (tracheal) lumen, which is clear in color and shorter in length. Its distal end is open. Insertion is accomplished by elevation of the mandible, anterior displacement of the tongue, followed by insertion of the Combitube® in a downward-curved motion keeping the tongue in the midline. Insertion may be aided by prewarming the Combitube in a bottle of warm saline or bending it for some time prior to its insertion (Lipp maneuver). Inflation of the large oropharyngeal cuff should be performed first, followed by inflation of the distal, esophageal cuff. Ventilation should be attempted via lumen #1 (esophageal lumen) first. If ventilation is unsuccessful, then the device may be pulled back 1 to 2 cm and ventilation reattempted. If ventilation remains unsuccessful, then ventilation via lumen #2 (tracheal lumen) should be attempted. If this is also unsuccessful, the device should be removed. This device is useful in cases in which vocal cord visualization is not possible, such as the patient with regurgitation, airway bleeding, difficult anatomy, or when there is poor access to the patient. Video 6.2 Combitube Insertion Techniques

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Figure 6.6 Combitube® (Covidien, Mansfield, MA).

The Rusch Easytube® (Teleflex Medical, Research Triangle Park, NC) is a double-lumen rescue airway that is very similar to the Combitube®, yet with some differences (Fig. 6.7). The Easytube® is latex-free and it has a narrower tip, because its esophageal lumen ends just below the oropharyngeal balloon, unlike the Combitube®, which carries the two lumens down to the end, thus reducing the potential for trauma. The Easytube® is available in two sizes: the 28 Fr is available for patients with a height ranging from 90 cm to 130 cm and the 41 Fr is designed for patients taller than 130 cm. The technique of Easytube® insertion is very similar to the Combitube. The Easytube® also has a pathway between the two distal balloons for passing a tube exchanger or flexible fiberoptic scope, and it is a bit shorter than the Combitube. The distal balloon’s purpose is to block the esophagus. The ventilation path for gas is through the opening between the two cuffs. As with the Combitube, if ventilation through the primary esophageal lumen is unsuccessful, then ventilation via the #2 tracheal lumen should be attempted. The King LT®, King LT-DTM and King LTS-DTM (King Systems Corporation, Noblesville, IN) are similar in design to the Combitube® and Easytube®, with a ventilation port between two cuffs, but with several significant modifications. The King LT® device is reusable and is latex free. The King LT-D™ is a disposable version (Fig. 6.8). They are single-lumen devices with a tapered distal tip, which allows easier passage into the esophagus. The distal (esophageal) portion of the tube is occluded. The disposable King LTS-D™, on the other hand, has an open distal tip and has a secondary channel to allow suctioning of gastric contents (Fig. 6.9). There have been no reports of tracheal placement of the King LT series, yet if it did occur, then the device should be removed and reinserted. Insertion technique with the King LT® series is best accomplished with a lateral entry of the device into the oropharynx, followed by rotation toward the midline as it is inserted behind the base of the tongue. The connector base should be aligned with the teeth or gums, and both cuffs should be fully inflated. Following placement of the tube, ventilation may proceed with gentle withdrawal of the tube until ventilation becomes easy with adequate tidal volume and minimal airway pressure. It is important not to advance the tube with the cuffs inflated. Video 6.2 King LT® Insertion Techniques

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Figure 6.7 Rusch Easytube®. (Reprinted with permission from Thierbach AR, Werner C. Infraglottic airway devices and techniques. Best Pract Res Clin Anaesthesiol 2005;19(4):595–609.)

Figure 6.8 King LT-D® device.

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Figure 6.9 King LTS-D® device.

Supralaryngeal, Double Cuff, Airway Devices Tips • The Combitube, Easytube, and King LT series each have a double cuff with ventilatory openings between the cuffs. • The Combitube and Easytube are double-lumen tubes, whereas the King LTS-D has a second lumen for suctioning of gastric contents. • The Easytube and King LT are latex free. • Placement of the distal tip of the Combitube in the esophagus occurs more than 95% of the time. • Adequate ventilation of the lungs should be verified with exhaled carbon dioxide and appropriate delivery of tidal volumes as endotracheal placement may occur. • Monitor for adequacy of ventilation and anesthetic plane (total compliance, capnography, leak fraction, etc.) during anesthesia maintenance. • The King LT and King LT-D have a tapered, occluded distal tip, which allows easier placement into the esophagus. No reports of endotracheal placement have been described with these devices. • Following insertion of the devices, slow withdrawal with ventilation is necessary to ensure adequate tidal volume and minimal airway pressure. • Do not advance the device if the cuff(s) is inflated.

Intubating Supraglottic Airways The Intubating LMATM (ILMA; LMA North America, San Diego, CA), known as the LMA FastrachTM, was described by Dr. Archie Brain in 1997 in the British Journal of Anaesthesia (Fig. 6.10). Shortly thereafter, it became available for commercial use in the United States. The ILMA provides an alternative method of intubating the difficult airway while allowing ventilation during the process. This airway device exhibits a moderately high success rate for blind intubation (90% to 96.2% with ≤3 attempts or adjusting maneuvers). When used with a FOB, however, success is even greater (up to 100%). The ILMA comes in three adult sizes (3, 4, and 5), and all have a large enough lumen

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Figure 6.10 LMA Fastrach. (Copyright image provided courtesy of LMA North America, San Diego, CA.)

to accommodate size 8.0 mm ID ETs. The ILMA has the basic features of a classic LMA with a few important modifications. It has a rather acute angulation, as well as a rigid guiding handle. There is a specific ILMA ETT that is wire-reinforced and designed with a special designed tip to allow for atraumatic passage through the glottis. The presence of an epiglottic elevating bar is another variation from the classic LMA. This allows a clear path for the ETT to enter the trachea. A transverse depth marker indicates the depth at which the tip of the ETT is at the level of the mask aperture. The insertion technique allows for standard insertion of the ILMA and inflation of the ILMA cuff, followed by insertion of the ETT through the LMA and into the trachea. There are several maneuvers that can be performed to allow an increased chance of a successful intubation via this device. Once the ILMA is placed, it should be repositioned by slight movements either in or out while hand-ventilating the patient. The breathing circuit’s expiratory valve should be partially closed to allow increased positive pressure within the breathing circuit. Utilization of the Chandy (two-step) maneuver has been shown to improve the success rate of blind intubation with the ILMA and should be performed. The guide handle is used to rotate the ILMA slightly within the sagittal plane to the position in which there is minimal resistance to bag ventilation (step one). By performing this maneuver, a downfolded epiglottis can be cleared. Tidal volumes can also be noted, and the best tidal volume should coincide with the least resistance. Following this, as the lubricated ETT is introduced, the guide handle is lifted (not tilted) slightly off the posterior pharyngeal wall (step two). This allows for a smooth passage of the ETT. Removal of the ILMA following endotracheal intubation is recommended, as there are reports of mucosal injury resulting from its rigidity. The LMA stabilizer rod is used to maintain the ETT in place while removing the ILMA. It is important to ensure proper oxygenation of the patient prior to the following steps. First, removal of the ETT connector is performed, followed by deflation of the ILMA cuff, but not the ETT cuff. The ILMA is gently removed while counterpressure is applied to the proximal end of the ETT. Once the proximal end of the ILMA is even with the ETT, the LMA stabilizer rod is inserted to keep the ETT in place until the ILMA is completely removed.

Video 6.4 Endotracheal Intubation using the Intubating LMA

Intubating Laryngeal Mask Airway Tips • The ILMA allows for passage of an ETT via its lumen. A specific ILMA ETT was designed for this purpose; it is wire-reinforced and has a special shaped tip. • Blind placement of a polyvinyl chloride ETT can be traumatic; it should be warmed in a bottle of irrigating solution and used in combination with a FOB. • Similarly to traditional LMA placement, the ILMA, should be passed along the hard palate, while holding the handle. • Following proper placement of the ILMA, small advancing and withdrawing maneuvers (∼5 cm) should be performed until the best ventilation is obtained. This usually clears a downfolded epiglottis and assures proper position. • Blind tracheal tube passage via an ILMA without good ventilation will likely result in failure. It is best to assure adequate ventilating prior to intubation attempts. • The dedicated ETT, with the vertical black line facing the operator, should be well lubricated and passed through the shaft of the ILMA. • Chandy’s maneuver has two steps: (1) rotate the ILMA slightly in the sagittal plane using the handle to assist in obtaining adequate ventilation, and (2) lift the ILMA perpendicularly by the handle away from the posterior pharyngeal wall as the ETT is advanced. A third maneuver, such as thyroid pressure, may also be performed to allow smooth passage of the ETT into the trachea. • If resistance to ETT advancement occurs, then it is most likely caused by a downfolded epiglottis or impaction into of ETT against the arytenoids. Correction is achieved by slight withdrawal of the ETT or ILMA. Alternatively, a different sized ILMA may be necessary.

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It is important to remove the stabilizer rod prior to unthreading the ILMA over the ETT, as damage may occur to the pilot balloon. It is also important to determine that the ETT has not been displaced during the procedure. After proper positioning is confirmed, the ETT connector is reattached to the ETT and ventilation may be resumed. Resistance to ETT advancement may be caused by impaction of the ETT into the tracheal wall. If this occurs, then a slight withdrawal of the ETT with rotation during subsequent advancement should correct the problem. If this fails, then the problem might be a downfolded epiglottis and correction of this problem may require slight withdrawal of the ILMA (no more than 6 cm) and reinsertion or complete withdrawal. Do not deflate the cuff during this maneuver. If the ILMA is too small, then the epiglottis will be out of reach of the epiglottic elevating bar. Attempting to pass the ETT through the ILMA will result in obstruction about 3 cm following the transverse line on the ETT. A larger ILMA may be required in this instance; if one is not available, then elevation of the thyroid cartilage can improve conditions for intubation. Alternatively, if a too-large ILMA is placed, then resistance may be noted about 4 cm to 5 cm past the depth marker. If this occurs, then the ETT may be wedged between the mask tip and the cricoid cartilage. If an alternate sized ILMA is not available, then caudal displacement of the larynx via mild pressure on the thyroid cartilage may facilitate endotracheal intubation. The ILMA has been used with a great deal of success with individuals having Mallampati 4 airways, cervical spine injuries, and other challenging airways.

6 Supraglottic Airway Devices

58 • Following verification of proper placement of the ETT, removal of ILMA is accomplished by deflation of ILMA cuff and removal of ILMA with the use of a stabilization rod to keep the ETT from becoming displaced. When the pilot cuff is at the entrance of the ILMA, the ETT should be reachable at the oropharynx. The stabilization rod is then removed, followed by removal of the ILMA. The ETT connector should be removed prior to insertion of the stabilization rod into the ETT. • If desired, FOB may be used to aid placement of the ETT and should be considered when blind placement fails. • Adequate lubrication of the ETT, as well as ample head and neck extension, may enhance the success of intubation via the ILMA.

The airQ® Intubating Laryngeal Airway (ILA; Cookgas, Mercury Medical, Clearwater, FL) was invented by Dr. Daniel Cook and introduced into clinical practice in 2004. It is specially designed with a hypercurved tube to mimic the anatomy of the oropharynx (Fig. 6.11). This helps prevent excessive bending and kinking of the airway tube. Also, its large oval mask cavity allows intubation with standard ETTs. Another feature is the keyhole design of the airway outlet, which aids in directing the ETT toward the laryngeal inlet. In addition, three internal ridges are located in the distal portion of the mask, and these attempt to mimic the shape of the posterior pharynx. This provides increased airway stability, smooth insertion, and better airway alignment. Three sizes are available: 2.5 for 20 kg to 50 kg, 3.5 for 50 kg to 70 kg, and 4.5 for 70 kg to 100 kg patients. Prior to insertion, deflation of the cuff is followed by application of water-based lubricant to the posterior aspect of the ILA. The insertion technique is similar to the LMA, with special attention to the possible need for minor manipulation to advance the ILA past the upper pharynx. If intubation of the trachea is desired, then proper placement of the ILA should be assured by assessing adequate ventilation, as well as relaxation of the laryngeal musculature and vocal cords with either adequate anesthesia/muscle relaxants or adequate topicalization. To facilitate proper placement, the “Klein Maneuver,” in which the air-Q is withdrawn and reinserted with a jaw thrust, can be performed by grasping the lower incisions. The patient should be ventilated with 100% oxygen for 3 minutes to 5 minutes prior to attempting endotracheal intubation. The ETT should also be lubricated and its cuff deflated. Insufflation of the cuff with 4 mL to 7 mL of air should prevent the mask from being placed too deeply, which would place the keyhole aperture under the larynx instead of proximal to it. The connector of the ILA should be removed, and the ETT should be inserted to a depth of 12 cm to 15 cm. This should ensure that the tip of the ETT is at the opening of the ILA tube within the mask cavity. Further advancement may be accomplished with a FOB, a stylet, or using a blind approach. If the FOB method is used, then the FOB is advanced into the trachea, the carina is visualized, and the ETT is advanced over it using the FOB as a guide. The FOB is then removed and the ETT is attached to the circuit, followed by assessment of adequate ventilation. If an intubation stylet is used, it should be passed through the ETT into the trachea. The stylet may be felt passing over the cricoid ring, and the ETT may be advanced over the stylet into the trachea. Following inflation of the ETT cuff, its connector is replaced and the stylet is removed. Verification of the correct position is determined by assessing expired carbon dioxide. If a blind technique is utilized, then the ETT is slowly advanced through the ILA into the trachea. Capnography can be utilized throughout the positioning either in the spontaneously ventilating patient or via position pressure ventilation in the anesthetized and paralyzed patient.

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Figure 6.11 airQ® Intubating Laryngeal Airway (ILA). (Copyright image provided courtesy of Mercury Medical, Clearwater, FL.)

Verification of correct position is as described above. After successful intubation of the trachea is accomplished, the ILA Removal Stylet is placed into the ETT until a snug fit is obtained. The stylet adapter is then rotated 90° until the adapter engages the ETT. The cuff of the ILA is then deflated, and the ILA is slowly removed over the ETT-ILA stylet until removed from the patient’s mouth. Subsequently, the ILA stylet is rotated oppositely and removed from the ETT. The ETT connector is then replaced, and proper position of the ETT is reconfirmed. Additional tips to successful placement include adequate lubrication, ample head and neck extension, and use of a Parker Flex TipTM tracheal tube (Parker Medical, Highlands Ranch, CO). Advantages of the ILA over the ILMA include its design, which facilitates reliability and ease of insertion. Additionally, it can be left in place following intubation and is designed to accommodate standard polyethylene ETTs. Finally, the ILA Removal Stylet is designed with grooves to allow spontaneous ventilation through the ETT during its exchange. The ILA can remain in place, with its cuff deflated. It can be used as a bridge to extubation, in which at the end of the procedure, the ETT can be removed while the patient is still under deep anesthesia or awake, as in routine extubation. The ILA can then be removed when the patient is completely awake. Video 6.5 Fiberoptic-guided Intubation via the airQ ILA

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Air-Q Intubating Laryngeal Airway (ILA) Tips • • • •

The hypercurved tube design of the ILA prevents bending and kinking of the airway tube. The keyhole design of the airway outlet aids in directing the ETT toward the glottis. No specialized ETT is necessary; a standard ETT is appropriate. Adequate lubrication of the ETT, ample head and neck extension, and use of Parker Flex Tip tracheal tube may be used to enhance the success of intubation via the ILA. • Physical maneuvers, such as ample head and neck extension and slight withdrawal and reinsertion of the device, along with jaw thrust, may also enhance intubation success. • To enhance success, a FOB may be used to aid placement of the ETT. • The ILA Removal Stylet should be used for safe removal of the ILA. After removing the ETT connector, insert the ILA Removal Stylet into the ETT and perform a 90° rotation to engage the stylet. Following this maneuver, the ILA cuff is deflated and removal of the ILA is performed. The ILA stylet should be rotated in an opposite fashion for its removal from the ETT.

Figure 6.12 The Ambu® Aura-iTM shown with the Ambu® aScope™. (Copyright image provided courtesy of Ambu Inc., Glen Burnie, MD.)

Rescue Maneuvers Difficulties may arise during placement of any of the SADs. Difficulty in placing an LMA is most often caused by improper placement technique or inappropriate size of the LMA. Proper placement can be verified by performance of a leak test by partially closing the expiratory valve; 16 cm to 20 cm water pressure should be reached prior to auscultation of a leak. Also, correction of improper placement can be performed by 2 cm to 4 cm movement of the LMA and rechecking for a leak, as noted. If these actions do not correct the problem, then a different size LMA (usually smaller) is needed. Alternatively, breath holding may occur if the depth of anesthesia is insufficient. This can be corrected by administration of topical, inhalational, or intravenous anesthesia. Difficulty with Combitube, Easy Tube, or Laryngeal Tube placement can also occur. Lifting the jaw with the nondominant hand or insertion of the device laterally initially may facilitate placement. Although not necessary, direct laryngoscopy can also facilitate placement of any of the supraglottic devices.

Summary The introduction of the LMA has been described as the most important advance in airway management over the last 50 years. Since the initial Classic LMA developed by Archie Brain the 1980s, there have been numerous advances in SADs that enable the caregiver to not only ventilate but also to use as a conduit for endotracheal intubation. Common problems associated with placement of a SAD include improper insertion (most often too deep), securing the device inadequately, and cuff over-inflation. Advantages of SADs include low cost, ease of training personnel, and a wide variety of styles suitable for different patients.

Suggested Reading Verghese C, Mena G, Ferson D, Brain AI. Laryngeal mask airway. In: Hagberg CA, ed. Benumof’s Airway Management 3rd ed. Philadelphia, PA: Mosby Elsevier; 2012:443–465. Cook TM, Hagberg, CA . Non-laryngeal mask airway supraglottic airway devices. In: Hagberg CA, ed. Benumof’s Airway Management, 3rd ed. Philadelphia, PA: Mosby Elsevier; 2012:466–507. Dorsch JA, Dorsch SE. Supraglottic airway devices. In: Understanding Anesthesia Equipment, 5th ed, Philadelphia, PA: Lippincott Williams and Wilkins; 2008:461–519.

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The Ambu® Aura-iTM (Ambu, Copenhagen, Denmark) was only recently introduced into clinical practice. It has a curved design (Fig. 6.12) that allows easy passage into the pharynx and its desired location, like the previously mentioned intubating conduits. It has the ability to pass an ETT through it to perform endotracheal intubation. This is accomplished by placing the appropriately sized, lubricated ETT into the Aura-i. An ETT size guide is present on the tube portion of the Aura-i. A FOB is then placed into the ETT and guided through the glottis. The ETT is then advanced over the FOB into the trachea and the FOB removed. Confirmation of proper placement of the ETT is determined by expired carbon dioxide and auscultation of the chest. Removal of the Aura-I can be accomplished by the “tube-to-tube” method, if desired. Otherwise, the device may be left in place and its cuff deflated. The cuff can be reinflated at the end of the surgery and the device used as a bridge to extubation, as mentioned above. Currently, there have not been any descriptions of “blind” intubations using the Aura-i.

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Chapter 7

Endotracheal Tubes and Laryngoscopy Techniques William H. Daily, MD

Objectives • • • •

Discuss the most current, commonly used endotracheal tubes. Describe the use of double-lumen endotracheal tubes and bronchial blockers. Describe direct laryngoscopy using Miller and Macintosh blades. Discuss types and use of indirect rigid laryngoscopes and video laryngoscopes.

Introduction The use of an endotracheal tube (ETT) for ventilation of critically ill patients or patients requiring inhalational anesthesia is well documented. Several types of ETTs have been developed to aid in anesthetic delivery for a variety of surgical procedures. Especially important is the use of double-lumen ETTs for one lung ventilation. Until the mid-1990s, direct laryngoscopy with either a Miller or Macintosh laryngoscopy blade was the “only game in town.” Since that time, new laryngoscopes have been developed, including both indirect rigid and video laryngoscopes (VLs). These new devices have greatly improved the ability to manage difficult airways.

Endotracheal Tubes Although there are many types of ETTs, this chapter will be limited to single-lumen ETTs, double-lumen ETTs, and their most popular variants.

Single-Lumen ETTs The single-lumen tube is the most commonly used ETT. It has the advantages of low cost and availability in multiple sizes, shapes, and features (e.g., laser, reinforced, accessory port for suctioning, etc.). The most commonly used sizes of oral ETT are 7.0 mm for adult females and 8.0 mm for adult males. Although a larger size can be tolerated, there is risk of tracheal mucosal injury as well as damage to laryngeal structures. Using a smaller ETT is associated with increased turbulent

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airflow, which leads to increased work of breathing. In addition, blockage of the ETT with secretions or by positioning of the head or neck can compromise the internal diameter. The Endotrol® ETT (Covidien, Mansfield, MA; sizes 4.0–9.0 mm) has a unique design that allows anterior displacement of the tip of the ETT by pulling on a pull ring attached to a plastic cable running on the concave surface of the ETT (Fig. 7.1). The Endotrol® tube has been used for blind oral or nasal intubations as well as in conjunction with video laryngoscopy. Following intubation, care must be taken to ensure the pull ring is not continuing to exert pressure on the tip of the ETT. This has been reported to cause obstruction with the ETT tip abutting the tracheal wall. The Parker Flex-TipTM ETT (Parker Medical, Highlands Ranch, CO; sizes 2.5–9.5 mm) has a flexible, curved, centered, tapered distal tip geometry that is designed to facilitate rapid, easy, nontraumatic intubation (Fig. 7.2). When this is advanced into contact with protruding features of the airway (such as the vocal cords or nasal turbinates), it is designed to flex and slide gently past them, rather than impinging on them and causing trauma. The Parker Flex-Tip™ ETT is available in a wide variety of formats including cuffed and uncuffed models ranging in whole and half sizes from 4.0 mm to 9.5 mm and 2.5 mm to 7.0 mm, respectively. It is also available in a reinforced model (sizes 3.0–5.0 mm uncuffed, and 5.5–9.5 mm cuffed). Finally, it is also manufactured in preformed oral and nasal formats, cuffed as well as uncuffed. The uncuffed run from 3.0 mm to 7.0 mm, and the cuffed is available from 4.0 mm to 9.0 mm. The Endoflex® ETT (Merlyn Associates, Tustin, CA; sizes 4.0–10.0 mm) enables manipulation of the distal tip of the ETT into proper position without the use of a stylet. A nylon cable is connected to a friction lock on the ETT near the universal connector (Fig. 7.3). Withdrawal of the friction lock articulates the distal tip of the EndoFlex® ETT. This allows easier passage of the ETT through the glottic opening. Release of the friction lock allows the EndoFlex® ETT to resume its (A)

(B)

Figure 7.1 The Endotrol® ETT in (A) neutral conformation and (B) with traction on the pull-ring resulting in anterior displacement of the tip. (Reprinted with permission from Cattano D, et al. Endotrol tracheal tube assisted endotracheal intubation during video laryngoscopy. Intern Emerg Med. 2012;7(1):59–63.)

Figure 7.2 Parker Flex-TipTM ETT (Parker Medical, Highlands Ranch, CO).

Figure 7.3 Endoflex® ETT. (Copyright image provided courtesy of Intersurgical, Liverpool, NY.)

initial form. The EndoFlex® ETT has been used with a variety of VLs. It is also available in preformed oral and nasal as well as cuffed and uncuffed models. Finally, it has two cuff variations: a low-volume, tapered cuff or an elongated, rounded high-volume/low-pressure cuff. Although there are many different bronchial blockers currently available, only a few will be addressed in this chapter.

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If one-lung ventilation is desired yet utilization of a double-lumen tube (DLT) is impractical because of difficult airway anatomy, decreased size of the tracheal lumen, or a need for postoperative mechanical ventilation, then placement of a bronchial blocker via a single-lumen ETT may be indicated. The Univent® (Fuji Systems; Tokyo, Japan) is a single-lumen ETT that has a small channel within its wall through which a bronchial blocker passes (Fig. 7.4). It underwent design modifications in 2001. The new Torque Control Blocker (TCB) Univent® has a more flexible shaft made from a softer, more compliant, medical grade material that is easier to direct. The bronchial blocker has a lumen that allows suctioning of the collapsed lung as well as a low-pressure, high-volume cuff. Initial placement of the Univent® is the same as any single-lumen tube, with the exception that following insertion through the glottic opening, the ETT is rotated 90o to allow passage of the bronchial blocker into the targeted bronchus. The position of the bronchial blocker is verified by use of a fiberoptic bronchoscope (FOB). Following placement, a locking cuff at the proximal end of the blocker is secured. Tips for successful placement include rotation of the head, as well as placement of the bronchoscope into the contralateral bronchus to divert the bronchial blocker to the desired location. The Arndt Endobronchial Blocker® (Cook Critical Care; Bloomington, IN) or wire guided endobronchial blocker has a distal snare designed to ensnare a FOB (Fig. 7.5). The FOB is then advanced into the desired bronchus. The loop is loosened and the blocker may be advanced distal to the FOB into the selected bronchus. This device may be utilized when the patient is already intubated and switching to a DLT is undesired or potentially dangerous. This is available in a 5 Fr pediatric size and a 9 Fr adult size. The Cohen Endobronchial Blocker® (Cook Critical Care; Bloomington, IN) has a rotating wheel that easily deflects the soft tip into the desired bronchus. The blocker cuff is pear-shaped and takes approximately 6 mL to 8 mL to seal the bronchus. The blocker size is 9 Fr with a 1.6 mm central lumen that allows limited suction and oxygen insufflation.

Double-Lumen Endotracheal Tubes When there is a need for one-lung ventilation, a DLT may also be utilized. Indications include lung isolation because of infection or hemorrhage, need for bronchial pulmonary lavage, and control of distribution of ventilation. There are both advantages and disadvantages with use of a DLT. When positioned properly, the DLT allows independent ventilation of each lung, either separately or

Figure 7.4 Univent®. (Copyright image provided courtesy of LMA North America, San Diego, CA.)

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Figure 7.5 Arndt Endobronchial Blocker® (Cook Critical Care; Bloomington, IN).

in unison. Additional advantages include treatment of desaturation, larger lumen for suctioning, egress of gases, and, finally, more secure positioning. The DLT has a bronchial port and a tracheal port. These are designated as left or right, depending on whether the bronchial port goes to the left or right bronchus. The bronchial port, cuff, and connector are blue. The tracheal port, connector, and cuff are clear. The DLT comes in a variety of sizes, and most commonly a left DLT is selected to avoid blockage of the right upper lobe bronchus. Although right-sided DLT placement is more difficult, it may be indicated with tracheal or left mainstem bronchus abnormalities. The ideal size results in a rear seal of the bronchial lumen with an uninflated cuff. Generally, a 37 Fr DLT is utilized for the adult female and a 39 Fr DLT is used for the adult male, although adult sizes also include 35 and 41 Fr. Sizes 20 Fr and 32 Fr are also available. The appropriate depth of insertion of the DLT correlates with the height of the patient. For patients 170 cm to 180 cm tall, the average depth for a left-sided DLT is 29 cm. The DLT should be either advanced or withdrawn 1.0 cm for every 10 cm increase or decrease in height. The intubation technique requires the DLT to be placed in the oropharynx in an anterior-posterior orientation until the bronchial port passes through the glottis. The stylet is then removed and the tube is rotated 90º to the side of the bronchial lumen. It is important to remove the stylet prior to advancement to avoid damage to the laryngeal or tracheal mucosa. If resistance is met when attempting to advance the DLT, then a smaller size should be considered. Following placement of the DLT into the trachea, fiberoptic verification of the location of the bronchial port should be determined. The blue bronchial cuff should be positioned just below the carina in the appropriate bronchus. Inflation of the blue bronchial balloon under direct visualization helps verify proper placement. Care should be taken to ensure that the bronchial cuff does not herniate over the carina and that the tracheal cuff does not block the carina. Following verification of positioning of the bronchial port, it is possible to isolate a lung by inflating the bronchial cuff and clamping either the tracheal or bronchial connector. If a DLT was used for lung separation, then the risks and benefits of changing to a single-lumen tube (SLT) must be considered. The main advantage

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to leaving the ETT in place is that the hazards associated with an ETT change in a difficult airway are avoided. If the DLT is to be changed, then it should be done under direct vision, if possible. If adequate laryngeal exposure is not possible via DL or VL, then an airway exchange catheter (AEC) may be used to exchange a SLT for a DLT pre-operatively or a DLT for a SLT postoperatively. The AEC by Cook specifically designed for DLT exchange is extra firm, which is stiffer, although its distal tip is actually flexible.

One Lung Ventilation: Double-Lumen Tube and Bronchial Blockers Tips • Use of a DLT is considered the gold standard for one-lung ventilation. • To minimize the risk of tube displacement, the left mainstem bronchus should be intubated unless a left-sided DLT will interfere with surgery (e.g., a left pneumonectomy). Right-sided DLTs are more difficult to place properly because of the risk of obstructing the right upper lobe bronchus. • A FOB should be used to verify position of the endobronchial cuff following placement. • A Univent® tube or SLT with an endobronchial blocker should be considered if a difficult airway is anticipated, postoperative mechanical ventilation is considered, or the patient is already intubated. • Ventilation with 100% oxygen during the use of FOB is strongly recommended when used for DLT or SLT and bronchial blocker placement. • Generous application of lubricant to the FOB will aid with its utilization during positioning of the bronchial blocker. • The DLT, with its larger lumen, provides better suctioning of the bronchus as well as more rapid deflation of the desired lung. • Identify problems early. In the event of oxygen desaturation, verify proper placement of the bronchial and tracheal tube, utilize 100% oxygen, and ensure adequate ventilation. If DLT is used, then the nondependent lung can have CPAP applied providing partial re-expansion of the nondependent lung. Unfortunately, if a bronchial blocker, with its obstructive design, is used, CPAP cannot be applied to the nondependent lung. • Removal of the bronchial blocker at the conclusion of the operation will allow for continued ventilation with the in situ SLT. CPAP = continuous positive airway pressure

Direct Laryngoscopy Direct laryngoscopy requires direct visualization of the airway anatomy by the individual performing the intubation via the use of a laryngoscope. Preparation of any necessary equipment, as well as adequate patient positioning, is required to ensure optimal conditions for successful endotracheal intubation. There are two basic types of laryngoscope blades: curved, similar in design to the Macintosh blade (Fig. 7.6), or straight, similar in design to the Miller blade (Fig. 7.7). Both are designed for right-handed individuals; with the laryngoscope handle held in the left hand and the ETT held and passed into the trachea with the right hand. There are numerous variations of size and shape of these two basic designs. Insertion of the laryngoscope into the patient’s mouth requires prior assessment of the patient’s dentition to determine existing or anticipated dental issues. In the

Figure 7.6 Macintosh blade.

Figure 7.7 Miller blade.

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case of obviously damaged or loose teeth, the patient must be informed of the possibility of injury to these teeth during intubation. There are numerous brands of these preformed dental shields that reduce the force applied to the teeth and potentially reduce the probability of tooth damage during laryngoscopy. However, the shield with the most force reduction capability, Ormco SportsGuardTM, (Ormco Corporation, Orange, CA) is rather large and relatively expensive. Nonetheless, protection can also be accomplished with either a small gauze pad or alcohol wipe package. These maneuvers can cause decreased visibility of the glottis if the patient has decreased mouth opening. Following proper patient positioning, preoxygenation, and administration of general anesthesia, it is important to assess the ability to mask-ventilate the patient prior to the administration of a paralytic agent. Following these steps, insertion of the laryngoscope into the mouth can follow

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one of two methods. The extra-oral technique requires extension of the neck by placing the right hand on the vertex of the skull and moving it in a posterior fashion. Alternatively, the scissors maneuver involves using the thumb of the right hand pressing downward on the lower right molar teeth while the right index finger applies pressure to the right upper molars. This is then followed by insertion of the blade into the mouth and retraction of the lower lip with the little finger of the left hand. Both of these versions then require slow advancement of the Macintosh blade into the mouth and movement of the tongue to the left. Also, special concern to keep pressure off the lips and teeth is accomplished by lifting the laryngoscope in a 45° direction after placement into the vallecula (where the base of the tongue meets the epiglottis.) If a straight blade is used, the tip of the laryngoscope blade is placed at the posterior surface of the epiglottis and then elevated to expose the glottis. It is important to lift the laryngoscope with the left shoulder and arm, as flexing the wrist might cause damage to the upper teeth or gum. Following glottic visualization, advancement of the ETT between the vocal cords is accomplished. Verification of proper placement of the ETT is determined by visualization of the ETT passing through the glottis, auscultation of the lungs, and verification of expired carbon dioxide. Curved blades are likely to be less traumatic to the teeth and epiglottis and have a lower incidence of laryngospasm than straight blades. Another advantage of the curved blades is that they provide more space for passage of the ETT through the oropharynx. The straight blade, on the other hand, gives a better view of the glottis in patients with a floppy epiglottis or anterior larynx. This is beneficial in infants and children. Also, comparison of curved and straight blades shows less force, head extension, and cervical spine movement with the straight blade. Improvement of the view of the larynx can be accomplished via external laryngeal pressure by applying backward, upward, and rightward pressure (BURP) to the thyroid cartilage. The individual performing the laryngoscopy can apply the pressure initially with his right hand and then have an assistant apply the same pressure at the time of intubation. A common problem associated with laryngoscopy is insertion of the blade too deeply into the pharynx, which causes elevation of the larynx and visualization of the esophageal opening. Slight withdrawal of the blade usually corrects this issue. Also, if the tongue flips into the right side of the oropharynx, then obstruction of the glottic view may occur. This is corrected by repositioning the tongue in the correct position onto the left side of the laryngoscope blade. Additional space can be created by pulling the right lip or cheek laterally.

Direct Laryngoscopy Tips • Assessment of the airway is critical prior to attempting laryngoscopy. • Following preoxygenation and induction of anesthesia, assessment of ability to ventilate the patient is necessary prior to administration of paralytic agents. • If a Macintosh blade is used, then the tip of the blade should be placed into the vallecula. Alternatively, if a Miller blade is used, then the blade should elevate the posterior aspect of the epiglottis. • The blade is then lifted in a 45º angle to avoid injury to teeth or lips. • Following visualization of the glottis, the ETT may be introduced between the vocal cords. • The number of intubation attempts should be kept to a minimum (usually < 3) to minimize airway trauma. • If it is difficult to pass the ETT, then turn the ETT 90º counterclockwise to facilitate ETT passage through the glottis. If difficulty continues, then an intubation stylet may be utilized. Special ETTs, such as the Parker Flex-Tip™ tube, may also be considered.

The Bullard LaryngoscopeTM (BL; ACMI Corporation, Southborough, MA) was developed by Dr. Roger Bullard and introduced into clinical practice in the late 1980s. This is an indirect rigid fiberoptic laryngoscope that has a blade specially designed to follow the contour of the oropharynx and rest under the epiglottis (Fig. 7.8). As the blade is anatomically shaped, this allows indirect laryngoscopy without the usually required alignment of the oral, pharyngeal, and laryngeal axes. This is beneficial for patients with limited mouth opening or cervical spine instability. Two light sources are available: a battery-powered handle or a flexible fiberoptic case connected to a highintensity light source (e.g., halogen or xenon). The eyepiece has an attachable diopter for correction of visual acuity. A video camera may be attached to the eyepiece. The BL may be used in awake or anesthetized patients. If using one of the stylets, they must be lubricated and attached to the BL in the appropriate fashion. If the older, solid stylet is used, then the ETT adaptor should be removed and the ETT should be positioned properly over the stylet so that the distal end of the stylet projects through the Murphy eye of the ETT. If the newer, hollow-core stylet is used, then the ETT is simply passed over and not threaded through the Murphy eye. A 3.7 mm channel with a Luer-Lock connection can be used for suction, oxygen insufflation, or the administration of local anesthetics. A second part accepts a nonmalleable intubating stylet, designed to follow the contour of the laryngoscope blade. The ETT should be warmed and lubricated prior to placement over the stylet. Anti-fog solution is applied, and the insertion of the BL into the oropharynx begins with the handle in a horizontal fashion, which is then rotated to the vertical plane upon insertion into the oropharynx. Subsequently, the blade is moved in a slightly caudad-posterior fashion and then lifted vertically. Once the glottis is visualized, the ETT is advanced off the stylet and into the trachea. The BL is then moved to the horizontal position and removed from the mouth. A common problem encountered with the BL occurs when the operator attempts to use the eyepiece continuously during insertion. The first viewing through the eyepiece should occur when the BL has been placed in the oropharynx behind the tongue. Occasionally, the tip of the ETT may impact the right arytenoid. If this occurs, a slight movement of the BL to the left should correct the problem. Alternatively, the ETT conformation may be reversed with the bevel pointing to the right. The BL is a good tool for difficult airways in which the patient has limited mouth opening or cervical spine movement. It is more rugged than a flexible FOB and more resistant to breakage.

Figure 7.8 Bullard LaryngoscopeTM (ACMI Corporation, Southborough, MA).

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Indirect Laryngoscopy

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Disadvantages include a limited angle of vision, problems with cleaning, a slightly longer time for intubation than direct laryngoscopy, and possible anterior placement of the stylet with an ETT greater than 7.5 mm. With the advent of VLs, the use of the BL has decreased.

Bullard Laryngoscope™ Tips • Prepare the BL by using a lens defogger on the distal tip of the BL prior to insertion. The oropharynx should be freed of secretions either by the use of suctioning or administration of an antisialagogue. • Use a tongue depressor to move the tongue anteriorly while placing the BL midline into the oropharynx. • There are two different stylets (one hollow, the other solid) that can be attached to the BL to facilitate intubation. The stylets should be lubricated with an oil-based lubricant so that the ETT can be easily advanced. Always load the ETT so as the ETT remains behind the distal lens. If neither stylet is utilized, then a styletted ETT may be considered. • If one of the stylets is to be used, then always keep the stylet tucked in the proper position under the blade, using the thumb of your dominant hard. The tip of the stylet should always be visualized when viewing via the eyepiece/monitor. • Once positioned in the oropharynx, do not lift the blade until a view of the glottis is achieved. It may not be necessary to lift the blade. • A plastic blade extender can be used to add length to the blade and lift a very floppy epiglottis. • Remember that the ETT is advanced over the stylet from the right of the device; therefore, the glottic view should be at the 10 o’clock position.

Video Laryngoscopy Video laryngoscopy has revolutionized the practice of airway management, and its use may become standard not only for difficult airways but for routine airways as well. In fact, VL is now included in the ASA Difficult Airway Algorithm and should be considered for patients with a known difficult airway. There are several advantages of these devices over direct laryngoscopy— their design often improves laryngoscopic views and increases intubation success in patients with difficult airways. Their use may be considered for expected or unexpected difficult airways, either as a primary device or as a rescue technique. There are several types of VLs currently on the market that differ in terms of portability, disposability, blade angulation, channeled versus nonchanneled, direct versus indirect vision, necessity for application of lens defogger, use of a stylet, and so forth. Although there is a steep learning curve with their use, these devices are not without complications or failure. When using any of the VLs, the oropharynx should be free of secretions either by suctioning or the use of an antisialagogue. The Berci-Kaplan DCI® (Direct Coupler Interface) Video Laryngoscope (Karl Storz GmbH, Tuttlingen, Germany) uses a Macintosh blade with a video camera and light source adapter placed into the handle. A cable from the handle attaches to a video monitor. This allows the image from laryngoscopy to be displayed on a video monitor, which allows easier viewing of the glottic opening and less anterior lifting of the blade. The C-MAC® (Karl Storz GmbH, Tuttlingen, Germany) is a newer version of this system and has an integrated video camera in the blade. The viewing angle is 60° to 80°, much larger than the 10° to 15° seen with standard DL. Still and video images may be stored on a memory card of the C-MAC. The D-Blade® (Karl Storz GmbH, Tuttlingen,

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Figure 7.9 C-MAC® System with D-Blade® (Karl Storz GmbH, Tuttlingen, Germany).

Germany) is the newest addition to the C-MAC system (Fig. 7.9). It has an elliptically shaped blade that curves more anteriorly than other VL blades, allowing for an easier glottic view in difficult laryngoscopy situations. The viewing angle is also 60º to 80º. It has been designed to be used when the C-MAC has failed or difficulty is expected with direct laryngoscopy. Use of these VLs requires application of anti-fog solution to the tip of the image light bundle. These devices allow for direct laryngoscopy or VL, as needed. As minimal cervical spine movement is needed for use of these devices, they are especially useful for patients with a cervical spine injury.

C-Mac, D-Mac Tips • Apply anti-fog solution to the lens prior to use. • If the epiglottis hinders the view, use the curved blade as a straight blade. • Utilization of stylet will assist in placement of ETT, although not necessary. The stylet should be passed to the level of the Murphy eye of the ETT, and shaped as “J.”

GlideScope® Video Laryngoscopes: The GlideScope®, (Verathon Inc., Bothell, WA) was developed by Dr. John Allen Pacey and was introduced as the first commercially available VL in 2001. It has a bend of 50° to 60° in the middle of its blade. It also has a video camera, a light emitting diode near the tip of the blade, and a heated lens that helps to prevent fogging. The image is displayed on a video monitor. A special stylet, the GlideRite® Stylet (Verathon, Bothell, WA), which is preformed to the curve of the blade, is recommended when using the GlideScope (Fig. 7.10).

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Figure 7.10 GlideRite® Stylet.

Under direct visualization, the blade is placed in the midline, and advanced into the oropharynx. When the blade is beyond the soft palate, it can be advanced under videoscopic guidance. The blade should be advanced into the vallecula but not farther, as a better view is obtained if it slightly more proximal. The styletted ETT is introduced into the mouth and past the right palatoglossal arch under direct vision and then can be passed into the glottic opening using videoscopic guidance. Care needs to be taken as the styletted ETT passes the base of the tongue so that it does not cause trauma to the posterior pharyngeal wall. Advancement through the opening is achieved by simultaneous withdrawal of the stylet and advancement of the ETT. If problems arise with the advancement of the ETT into the glottis, then a counterclockwise rotation of the ETT will often allow the ETT to “fall” into the airway. Using the GlideScope® as straight blade by lifting the epiglottis provides a better view of the vocal cords but this often creates a worse angle of entry for the ETT and should not be performed. A slight withdrawal of the laryngoscope will reduce upward laryngeal tilting, thereby reducing the angle between the ETT and the trachea. Use of the pediatric GlideScope® has been suggested for adult patients, as this reduces the depth of blade insertion and makes ETT advancement easier. Finally, some anesthesiologists prefer to place the styletted ETT into the mouth prior to placement of the GlideScope, as this decreases the likelihood of creating extra bends and encourages the operator to look at the patient and not the monitor while inserting the ETT. There are several GlideScope products currently available. First, the GlideScope® Video Laryngoscope (GVL) utilizes a reusable blade that connects to the video monitor. It is available in four sizes (2, 3, 4, 5) to accommodate small children to the morbidly obese, adult patient. The GVL (reusable) provides a clear view of the airway and tube placement, which enables quick intubation. Next, the GlideScope® Advanced Video Laryngoscope (AVL) is available in several different configurations: reusable or single use and the AVL preterm/small child or adult-sized laryngoscopes (Fig. 7.11). The single-use laryngoscopes utilize a reusable video “baton” that is encased in a disposable hard plastic sheath when needed for intubation (Fig. 7.12). The AVL preterm/small child is available in four sizes from 0 to 2.5. The GlideScope® Ranger is also available in either a reusable or single-use design (Fig. 7.13). It is available in two sizes, 3 and 4. It has a rugged design and is approved for military and EMS use. Finally, the GlideScope® Direct

Video 7.1 Tracheal Intubation Using the Glidescope®

Figure 7.11 The GlideScope® AVL single-use system. (Copyright materials provided as courtesy of Verathon, Bothell, WA.)

Figure 7.12 The GlideScope® AVL reusable system. (Copyright materials provided as courtesy of Verathon, Bothell, WA.)

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Intubation Trainer (Fig. 7.14) incorporates GlideScope® video technology with the feel of a standard Macintosh blade. This allows instruction of direct laryngoscopy, as an instructor can observe and critique either direct or indirect intubation technique as it occurs. Both single-use and reusable blades are available for use with this device.

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Figure 7.13 GlideScope® Ranger. (Copyright materials provided as courtesy of Verathon, Bothell, WA.)

Figure 7.14 GlideScope® Direct Intubation Trainer. (Copyright materials provided as courtesy of Verathon, Bothell, WA.)

GlideScope/GVL/AVL/Ranger Tips • Use an appropriately shaped stylet, such as the GlideRite Stylet®, which is specially designed for use with the GlideScope. Remember to remove the stylet once its tip has passed through the glottis, to avoid trauma. • Alternatively, a standard, malleable stylet may be used with a 90º bend 8 cm to 10 cm from the tip. The Truflex™ stylet (Truphatek International, Netanya, Israel) may also be used with in conjunction with the GlideScope® (see Chapter 7). • The size 3 blade is suitable for most adult patients. • Enter the oropharynx slightly to the right and displace tongue to the left, if possible, to create room on the right to manipulate the ETT. • Place the tip of the blade in the vallecula and no further. • If an unacceptable view of the glottis is obtained, then slightly withdraw the blade.

McGRATH® Video Laryngoscopes: Matt McGrath started work on the McGRATH® (Aircraft Medical, Edinburgh, UK) VL project in 1999, in response to a design brief issued by the Royal Society of Arts in London. The McGRATH® Series 5 VL was introduced into clinical practice in 2001. It is a fully portable VL with a 1.7-inch LCD screen on the handle that can tilt and rotate if needed (Fig. 7.15). It has an adjustable blade, which allows its use in different sized patients. The blade tips are disposable; however, the handle needs to be cleaned between cases. This VL can be used in a standard direct laryngoscopy fashion. If a better view of the laryngeal anatomy is warranted, then the practitioner can simply look at the video monitor. Insertion of the blade and ETT is similar to the GlideScope. Enter the mouth midline and rotate toward the larynx until the epiglottis is visible. The tip of the blade should be guided into the vallecula. The epiglottis should clearly be visible at the top of the screen to ensure vallecular placement. Endotracheal intubation may be enhanced by using an Endotrol® ETT. First a stylet is inserted into the ETT with a 30° “hockey stick” bend. The stylet is inserted only three-fourths of the length of the ETT. This allows the flexion of the Endotrol® ETT to be concentrated at the tip, where it is needed. This allows the tip of the ETT to be lifted above the posterior cartilages and placed through the glottic opening. The McGRATH® Mac is a newer model that was introduced into clinical practice in 2010. It has an anterior camera angle that is designed to improve grade of view. Its LCD screen is also located on the handle, but it is larger at 2.5 inches. The McGRATH® Mac also has a narrower blade of 11.9 mm, which allows greater movement without damaging the patient’s dentition. Prior to use, it is recommended to apply one or two drops of anti-fog solution on the tip of the blade, unless the fog-free blades are used. Video 7.2 Tracheal Intubation Using the McGRATH®

The Pentax-AWSTM Airway Scope (Pentax Medical Co., Montvale, NJ) is a portable, batterypowered VL. It has an attached 2.4-inch color LCD screen and an L-shaped introducer blade, which has a channel for tube loading and delivery, as well as a suction catheter (Fig. 7.16). The LCD screen has a target to assist in alignment of the screen with the glottic opening. The tip of the ETT is positioned just proximal to the tip of the camera cable. Like the Bullard, it is inserted into the oropharynx and directed under the tongue. When viewing the screen, the scope is maneuvered so that there is alignment of the target signal and the glottic opening. The ETT is advanced through the glottis and then separated laterally from the side channel. The Pentax Airway Scope works best when the epiglottis is lifted, in a similar fashion to a straight blade laryngoscopy. Removal of the Pentax Airway Scope is accomplished while holding the ETT in place. The Airtraq® (Prodol Meditec S.A., Guecho, Spain) is a disposable, portable, battery-powered, optical laryngoscope. It has seven color-coded sizes ranging from infant to adult. It has a pair of side-by-side channels, one for light and the other for passage of an ETT (Fig. 7.17). The light channel’s image from the distal tip is displayed on a proximal view chamber. Models have been developed to use with nasotracheal and endobronchial/double-lumen tubes. It has been recommended that the Airtraq® not be used in an anticipated difficult airway if a supraglottic airway cannot be used (limited mouth opening), high risk of aspiration exists, apneic period cannot be tolerated, or the patient has gross deformities of the upper airway. Fogging and secretions may also present a

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77 • Keep the tip of the ETT in view by direct vision until it can no longer be visualized, then look at the monitor to avoid soft palate or posterior pharyngeal trauma. • Only lift as necessary; a grade IIto III view may suffice; do not always try to see a grade I view or a more difficult angle of ETT entry into the glottis may be created. • If it is difficult to pass an ETT through the glottis, then see tips under BL.

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Figure 7.15 McGRATH® Video Laryngoscope. (Courtesy of LMA North America, San Diego, CA.)

problem. Suctioning the oropharynx or administration of an antisialagogue is encouraged prior to its use. Application of anti-fog solution is not necessary, as there is a built-in anti-fogging system for the optics that is activated by turning on the LED light. The Airtraq® should be turned on for 3 minutes to 5 minutes to prep the electronic defog system. The Airtraq should be inserted in similar fashion as the Bullard and Pentax-AWS™. Once the glottis is visualized, the ETT should be advanced. The ETT is then separated laterally from the channel, and the Airtraq® is removed from the mouth. Although visualization of the larynx is easily obtained with the Airtraq®, problems include difficulty changing direction of the ETT during insertion into the glottis. Additional problems may arise if the Airtraq® is situated close to the larynx, as the ETT is often directed into the right aryepiglottic fold. This can be corrected with an initial leftward turn of the ETT in the channel, followed by an immediate turning of the tip to the right, which lines up the tip of the ETT with the larynx. Alternatively, ensure that the tip of the Airtraq® is not too deep and close to the glottic opening. For optimal results, the glottis should be centered in the screen and not above the midline for successful intubation. If difficulty is encountered in advancing the ETT, then a bougie may be used

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Figure 7.16 Pentax-AWSTM Airway Scope. (Copyright image provided courtesy of Ambu, Glen Burnie, MD.)

Figure 7.17 Airtraq®. (Copyright image provided courtesy of Prodol Meditec S.A., Guecho, Spain.)

to direct the ETT through the glottic opening. As a completely disposable device, it may be too costly for routine use. A newer version, the Airtraq Avant®, features a reusable optic core with a disposable blade and eyecup. This system currently has two sizes, small (6.0–7.5 mm) and regular (7.0–8.5 mm). Utilization of a docking station allows for recharging and display of the remaining service life of optics. A wireless camera and display recorder may be utilized if desired. It is compatible with all Airtraq® models.

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Video 7.4 Tracheal Intubation with the Airtraq®

The King Vision Video LaryngoscopeTM (King Systems, Noblesville, IN) is another system that has a disposable blade with a 2.4-inch LED screen attached to the handle (Fig. 7.18). It is available in two sizes and has both a channeled and a nonchanneled (regular) blade. Lubrication of the ETT is recommended prior to use to ensure it passes easily within the channeled blade. The channeled blade has a special design with a soft outer edge that allows easy removal of the ETT from the blade following correct placement. No other channeled VL has this feature. Video 7.5 Tracheal Intubation Using the King Vision Video Laryngoscope™

Pentax, Airtraq, King Vision Tips • • • • •

Generously lubricate the ETT prior to loading it in the tube guide. Load the ETT in the guide until the tip of the ETT is proximal to the distal lens. Advance the blade in the midline of the oropharynx behind the tongue. Place the tip of the blade in the vallecula and do not advance further. Once positioned in the oropharynx, only lift the blade if lifting is necessary to achieve a view of the glottis. • Remember that the ETT is advanced from the right side of the device; therefore, it may be necessary to move the blade slightly off-center to the left. (A)

(B)

Figure 7.18 King Vision Video LaryngoscopeTM.

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Figure 7.19 Truview EVOTM 2.

The Truview EVOTM 2 (Rusch Medical, Teleflex, Research Triangle Park, NC) is an optical laryngoscope that shows a 42º anterior refraction in line of sight (Fig. 7.19). The Truview™ is an optical laryngoscope blade that is designed to provide indirect laryngoscopy with continuous oxygen insufflation. It is indicated for use in both standard and difficult intubation. It illuminates and expands the angular view of the larynx and adjacent structures, thereby facilitating endotracheal intubation. The Truview™ uses an optical system view-tube, which consists of prisms and lenses that extend vision beyond the distal end of the blade. The Truview™ is designed to decrease pharyngeal trauma and reduce the amount of force needed to successfully intubate a patient by greater than 30%. This helps protects against dental injury, reduces post-intubation sore throat, and minimizes risk of esophageal intubation. Also notable is the distal angulation of the distal blade. These features allow “around the corner” visualization. Following insertion of the Truview™ (via the midline approach), a styletted ETT is passed between the vocal cords. Care must be taken not to advance the Truview™ too deeply, as this will make endotracheal intubation more difficult to achieve. The newest generation of the Truview is the Truview PCDTM video and optical laryngoscope. It is fully portable, lightweight, and has interchangeable laryngoscope blades in five sizes (pediatric: 0, 1, 2; regular adult: 3; large adult: 4). Video output and recording is available using the Truview PCDTM Monitor.

Truview EVO Tips • Less force is required to intubate patients with the Truview EVO™ 2. • Avoid too-deep insertion of the device, as this will decrease the chance of successful endotracheal intubation. • Protection against dental injury and post-intubation sore throat is reported with the Truview EVO™ 2. • Another video option for the Truview PCDTM is to connect the device to the Storz Video System® (Karl Storz Endoscopy, Tuttlingen, Germany).

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Rescue Maneuvers The ASA Difficult Airway Algorithm should be adhered to when failure to intubate utilizing these laryngoscope techniques occurs. Ventilation must be maintained, utilizing any of the following techniques: ventilation via mask, supraglottic airway, jet ventilation, or, if necessary, a surgical airway.

Summary The use of VLs has increased over the last decade. Multiple systems are now available, with a wide variety of advantages unique to each particular laryngoscope. Successful use of these devices requires practice, as a good view of the vocal cords is often easily obtained but difficulty occurs with ETT advancement. Tips for successful use of these devices include pre-operative administration of glycopyrrolate, availability of suction, use of anti-fog solution on selected devices, and use of a properly sized ETT with a stylet in place (if indicated). If the practitioner is unable to see the vocal cords, then an assistant can apply laryngeal pressure or perform a mandibular lift. Once the vocal cords are visualized, advancement of the ETT may be performed while an assistant removes the stylet.

Suggested Reading Berry JM, Harvey S. Laryngoscopic Orotracheal and Nasotracheal Intubation. In: Hagberg CA, ed. Benumof’s Airway Management, 3rd ed. Philadelphia, PA: Mosby Elsevier; 2012:346–358. Levitan RM, Hagberg CA. Upper airway retraction: new and old laryngoscope blades. In: Hagberg CA, ed. Benumof’s Airway Management, 3rd ed. Philadelphia, PA: Mosby Elsevier; 2012:508–535. Marasigan B, Sheinbaum R, Hammer GB, Cohen E. Separation of the two lungs: double-lumen tubes, bronchial blockers, and endobronchial single-lumen tubes. In: Hagberg CA, ed. Benumof’s Airway Management, 3rd ed. Philadelphia, PA: Mosby Elsevier; 2012:549–568. Dorsch JA, Dorsch SE. Laryngoscopes. In: Understanding Anesthesia Equipment, 5th ed, Philadelphia, PA: Lippincott Williams and Wilkins; 2008:520–560. Dorsch JA, Dorsch SE. Tracheal Tubes and Associated Equipment. In: Understanding Anesthesia Equipment, 5th ed, Philadelphia, PA: Lippincott Williams and Wilkins; 2008:561–632. Dorsch JA, Dorsch SE. Lung Isolation Devices. In: Understanding Anesthesia Equipment, 5th ed., Philadelphia, PA: Lippincott Williams and Wilkins; 2008:633–660. Monaca E, Fock M, Doehn M, Wappler F. The Effectiveness of Preformed Tooth Protectors During Endotracheal Intubation: An Upper Jaw Model, Anesth and Analg 2007; 105(5):1326–1332. Savoldelli GL, Ventura F, Waeber JL, Schiffer E. Use of the Airtraq as the primary technique to manage anticipated difficult airway: a report of three cases. J Clin Anesth 2008; 20(6):474–477.

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Chapter 8

Intubation Stylets

Lara Ferrario, MD

Objectives • Explain the differences between the most commonly used commercially available intubation stylets. • List the advantages and disadvantages of intubation stylets. • Describe the techniques for using intubation stylets.

Introduction Over the past 60 years, a number of intubation stylets have been described, tested, and introduced into clinical practice. The aim of these devices is to aid either direct or indirect laryngoscopy in those situations when an unexpected poor visualization of the airway structures would otherwise compromise successful endotracheal tube (ETT) placement. The two major kinds of stylets are endotracheal tube guides and lighted stylets.

Endotracheal Tube Guides There are several commercially available endotracheal tube guides, which have similar characteristics (see Table 8.1). These are often shaped with a degree of angulation at the distal tip (coudé tip), can be solid or hollow, and share similar indications and handling techniques.

Coudé-Tip Stylets The Frova® Intubating Introducer (Cook Critical Care; Bloomington, IN) is an ETT guide introduced into clinical practice in 1998 (Fig. 8.1). It is available in 8 and 14 Fr, and is angulated 65° at the distal tip. It is supplied with a stiffening cannula that allows it to maintain a desired curvature, and two Rapi-Fit® adapters. These adapters allow for oxygenation/ventilation by attaching the introducer to a ventilator circuit, an Ambu bag, or a jet ventilator, and allow for confirmation of tracheal placement via capnography. The Portex® Tracheal Tube Introducer (PTTI), which became available in 1997 but is no longer being manufactured, the more recent Portex® Single-Use Bougie (PSUB) (Smiths

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Table 8.1 Endotracheal Tube Guides Solid stylets

Hollow stylets

Portex® Tracheal Tube Introducer

Frova® Intubating Introducer

Muallem ET Tube Stylet

Portex® Single-Use Bougie

Radlyn™ R-100 Stylet

Muallem ET Tube Introducer

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®

GlideRite Rigid Stylet

Aintree Intubation Catheter

Medical International; Ashford, Kent, UK), and the Muallem ETT Introducer (METTI) (VBM Medizintechnik GmbH; Sulz am Neckar, Germany) are 15 Fr stylets (Fig. 8.2). Graduation marks for accurate depth insertion are present on the PSUB and METTI. The Muallem ETT Stylet (METTS) (VBM Medizintechnik GmbH; Sulz am Neckar, Germany) also offers the advantage of three different diameters (8, 12, and 14 Fr). All of these stylets are malleable and designed with a coudé tip. With the exception of the PTTI (also known as the gum-elastic bougie), which was a reusable device that could be disinfected in cold-water solutions, the stylets described above are non-sterilizable, single-use introducers. Video 8.1 Tracheal intubation using Direct laryngoscopy and an Intubating Stylet

Figure 8.1 Frova® Intubating Introducer. (Permission for use granted by Cook Medical, Bloomington, IN.)

Figure 8.2 Portex® Single-Use Bougie. (Copyright image provided as courtesy of Smiths Medical North America, Rockland, MA.)

Intubation Catheter Tips • Prepare two different size ETTs in the eventuality of an unexpectedly narrow airway. • Use a sterile, petroleum gel-based ointment to lubricate the stylet. • Shape the stylet to a degree of curvature to best fit the patient’s anatomy (usually J-shaped). • Maintain the stylet in midline position, aligned with the right side of the patient’s nose. • Ensure that the coudé tip is facing upward prior to advancing the stylet to feel for the “tracheal clicks.” • Make sure that proper anesthetic technique is used (open cords). If muscle relaxation is adequate and the stylet is caught under the epiglottis, then other possible structural abnormalities may be the cause. • Never force a stylet over obstacles that are not properly visualized or identified. • If when advancing the ETT over the introducer, the ETT is caught on the laryngo-pharyngeal structures, then slightly retract and rotate the ETT counterclockwise so that the bevel is turned posteriorly prior to further advancement. • Failure to successfully pass the ETT over the introducer may also indicate the use of a smaller size ETT.

Radlyn™ R-100 Stylet The Radlyn™ R-100 Stylet (Radlyn LLC; Cincinnati, OH) is a single-size, semi-rigid, coudé-tip stylet that fits into a 7.0 mm ETT. It is equipped with a built-in tapered balloon at the distal tip that, upon inflation, creates a close fitting of the stylet within the ETT (Fig. 8.3). This feature is particularly helpful in the presence of swollen, redundant laryngo-pharyngeal tissues, as well as in those anatomic abnormalities characterized by the presence of a steep curvature at the larynx (i.e., ankylosing spondylitis). These situations typically are problematic because the stylet advances through the cords, but the ETT gets “hung up” on the arytenoids and is unable to advance forward. This stylet presents similar handling requirements as the previously described coudé tip stylets with the exception of the ETT advancement over the stylet.

Radlyn™ R-100 Stylet Tips • Because the presence of the cuff adds bulk and friction, lubricate the proximal portion of the stylet with a sterile, petroleum gel-based ointment. • Position the tip of stylet at the level of the Murphy eye of the ETT.

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Coudé-tip intubating stylets are easy to use and have a steep learning curve. They have proven to be useful and potentially life-saving devices during unexpected difficult intubations when only a portion of the laryngeal structures, such as just the tip of the epiglottis, can be visualized. The operator can shape the introducer prior to positioning the tip under the epiglottis and blindly advance the stylet into the trachea. Correct placement of the stylet is indicated by the perception of “tracheal clicks” as the coudé tip passes along the tracheal rings and by a “distal hold-up” as it reaches the small bronchi. Coughing in an unparalyzed patient is also indicative of tracheal placement. An ETT is subsequently advanced over the introducer into the correct position.

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• Inflate the stylet cuff to the ETT internal diameter. • Because the provided ETT stopper may present some difficulty at repositioning, the ETT can be secured in position by bending the stylet at the top of the ETT. • If the stylet tip is caught at the tracheal rings and cannot advance further, then slightly rotate the stylet counterclockwise.

Figure 8.3 Radlyn™ R-100 Stylet shown loaded in a standard ETT.

Aintree Intubation Catheter The Aintree Intubation Catheter (AIC; Cook Critical Care; Bloomington, IN) is a 19 Fr, hollow, single-use guide designed to exchange a supralaryngeal airway device for an ETT (Fig. 8.4). It is a straight introducer with an atraumatic blunt tip and graduation markings. The internal diameter (4.7 mm) is designed to accept a standard fiberoptic bronchoscope (FOB). The external diameter is 6.5 mm and fits in a 7.0 mm or larger ETT. It is also packaged with Rapi-Fit® adapters to allow either jet ventilation or ventilation through the anesthesia circuit or the Ambu bag. The presence of sideports on the distal end facilitates adequate airflow. The ability of the AIC to accommodate a FOB allows for a unique employment of this introducer in “cannot intubate, cannot ventilate” (CICV) scenarios. In these situations, a supraglottic airway device, such as a laryngeal mask airway (LMA) should be placed in accordance with the ASA Difficult Airway Algorithm. Once ventilation is achieved, the FOB loaded with an AIC is guided through the LMA and advanced into the patient’s trachea. Under fiberoptic visualization, the AIC is positioned approximately 1 inch above carina. The FOB is subsequently removed, followed by removal of the LMA by carefully sliding it over the AIC. Next, the ETT is advanced over the AIC. If necessary, oxygenation can be provided through the AIC by either jet ventilation or manual ventilation by attaching the AIC to the ventilator circuit. This intubating technique has been extensively described in literature and it can also be applied to nonemergent difficult airways as a technique for asleep fiberoptic intubation. Not uncommonly, a planned asleep fiberoptic intubation is rendered difficult by the loss of airway tone and redundancy of oropharyngeal tissue. Placement of an LMA will provide a clear passage for the FOB by displacing the oropharyngeal

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Figure 8.4 Aintree Intubation Catheter (AIC). (Permission for use granted by Cook Medical, Bloomington, IN.)

structures. The AIC technique provides the advantage that a larger sized ETT can be placed as compared to when an ETT is placed with fiberoptic guidance directly through an LMA.

Aintree Intubation Catheter Tips • Optimize the position of the LMA to achieve the maximum tidal volume ventilation with the best seal. This maneuver usually guarantees the proper placement of the LMA over the pharyngeal structures and provides better FOB visualization. • Lubricate the FOB as well as the proximal portion of the AIC with a petroleum gel-based ointment to facilitate passage of the AIC over the FOB, as well as of the ETT over the AIC. This will also help to prevent accidental displacement or removal of any of these devices secondary to friction and adhesiveness. • Use a lens defogger on the lens of the FOB. • Securely fasten the AIC at the distal end of the FOB to facilitate maneuverability of the scope. • Observe the AIC graduation markings to prevent trauma by excessive advancement of the catheter into the trachea. • Once removed, keep the LMA clean and available, should intubation fail. • Verify correct ETT position by FOB.

Videolaryngoscope Stylets The GlideRite® Rigid Stylet (Verathon Medical; Bothell, WA) is part of a range of rigid, stainless steel, reusable stylets, particularly designed to aid intubation with the GlideScope® video laryngoscopes as it conforms to the unique configuration of the GlideScope® blades. See Chapter 6 on video laryngoscopes for intubation technique and tips. The TruFlex™ Stylet (Truphatek International; Netanya, Israel) is a reusable, stainless steel stylet with a controllable tip. Depressing the lever provides anterior flexion of the distal tip of the stylet, facilitating ETT placement during videolaryngoscopy (Fig. 8.5).

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Figure 8.5 TruFlex™ Stylet shown loaded in a standard ETT. (Copyright image provided as courtesy of Truphatek International, Netanya, Israel.)

Lighted Non-Optical Stylets The lighted stylets such as the Surch-Lite™, (Bovie® Medical Corporation; Clearwater, FL), the Vital Signs Light WandTM Illuminating Stylet (Vital Signs; Totowa, NJ), and the Tube-Stat Lighted Stylet™ (Medtronic; Jacksonville, FL) are more recent versions of the Trachlight™, which is no longer manufactured. These stylets make use of the transillumination technique to blindly intubate the trachea and have been described in the literature as an alternative or as an aid to direct laryngoscopy, particularly in airways predicted to be difficult (e.g., high Mallampati score). In addition, they may be helpful at times when the presence of blood or heavy secretions limits visualization of the airway. However, because lighted stylet insertion is a blind technique, it may not be appropriate in patients with certain anatomical abnormalities, such as an intra-oral tumor. A combination technique with either direct or indirect laryngoscopy may be more appropriate.

Because increased soft tissue leads to difficulty with transillumination, this technique is less useful in the morbidly obese patient. In general, these stylets are portable and inexpensive and are less stimulating than direct laryngoscopy.

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An ETT is preloaded onto the stylet. The left hand of the operator lifts the supine patient’s jaw by gently grasping the mandible and displacing it anteriorly to facilitate the insertion of the stylet under the tongue. The stylet should be inserted using a retro-molar approach. Once inserted, the stylet should be kept midline and advanced under the tongue. A well-circumscribed “glow” (about the size of a half dollar) should appear in the midline of the patient’s neck at the level of the cricoid cartilage (Fig. 8.6). This indicates correct positioning of the stylet within the trachea. Subsequently, the ETT can be advanced over the stylet into proper position. Video 8.2

Intubation with a Lighted Non-Optical Stylet

Figure 8.6 Orotracheal intubation using a lighted non-optical stylet. (Reprinted from McGill J. Airway management in trauma: an update. Emerg Med Clin North Am 2007;25:603–622.)

Lighted Non-Optical Stylet Tips • Hold the lighted stylet in the dominant hand and advance it into the patient’s mouth by keeping the tip pointing upward. • Advance the stylet by keeping it behind the patient’s molars. • To assist visualization, the room lights should be dimmed. • If no light appears anteriorly, then the tip may be in the esophagus. If the light is present laterally, then the epiglottis may not be lifted adequately.

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Table 8.2 Lighted Stylets Non-optical stylets

Optical stylets

Surch-Lite™

Shikani® Optical Stylet

Vital Signs Guided Intubation Stylet™

Levitan FPS stylet

Tube-Stat Lighted Stylet™

Bonfils Retromolar Intubation Fiberscope™ Brambrink Intubation Endoscope™ SensaScope® Video RIFL® Scope

Lighted Optical Stylets Originally designed as an aid to difficult intubations, optical stylets have some advantages over endotracheal tube guides and non-optical lighted stylets. There is a substantial body of evidence that supports the use of these optical stylets in patients with limited neck mobility, small mouth opening, and redundant oropharyngeal soft tissue (e.g., large tonsils, large tongue, and floppy epiglottis). Different kinds of optical stylets are commercially available (see Table 8.2).

High-Resolution Optical Stylets The Shikani Optical Stylet® (Clarus Medical; Minneapolis, MN) is a high-resolution malleable fiberoptic stylet that comes in a preformed hockey-stick shape consisting of several illumination fibers and a fiberoptic bundle arranged in a coherent pattern (Fig. 8.7). With a length of 38.5 cm, the completely sealed stainless steel sheath can be sterilized in cold solutions (such as ethylene oxide or by immersion in a glutaraldehyde solution). Two different sizes are available: the adult version fits into a 5.5 mm ETT, and the pediatric shaft fits into 3 mm ETTs. An “adjustable tube stop” with an oxygen port allows the ETT to be firmly connected to the stylet and deliver oxygen. This stylet can be connected to different light sources, such as a fiberoptic cable or a fiberoptic laryngoscope handle through an adapter. The device offers two options for airway visualization: direct vision through an eyepiece or indirect vision via a camera, allowing the image to be shown on a monitor. The Clarus Video System (Clarus Medical, Minneapolis, MN) is similar to the Shikani Optical Stylet, except with digital camera at the tip and an attached LCD screen (Fig. 8.10). Video 8.3

Tracheal Intubation with the Clarus Video System

The Levitan FPS Stylet (Clarus Medical; Minneapolis, MN) is a shorter, streamlined version of the Shikani. With a length of 30 cm to closely mimic a standard malleable stylet, it requires that the ETT to be trimmed to 27.5 cm to 28 cm to achieve the correct standard stylet position (Fig. 8.8). It can be inserted into a 6.0 mm or larger ETT. The malleable steel portion of the device encloses optical and light-transmitting fiberoptic fibers that connect to an eyepiece and a removable light source. On the side of the stylet, a small hole is present that permits oxygen insufflation. The Levitan is intended for use with laryngoscopy, replacing a standard stylet for shaping and placement of the ETT. The Bonfils Retromolar Intubation FiberscopeTM (Karl Storz Endoscopy; Tuttingen, Germany) is a 40 cm long, rigid optical stylet with an external diameter of 5.0 mm and is designed with a preformed anterior tip curvature of 40° (Fig. 8.9). The adult stylet accommodates an ETT as small as 6.5 mm, whereas the pediatric stylet allows for 2.5 cm to 6.0 mm ETTs. The fiberoptic cable is encased in a stainless steel tube and connected to either a video monitor or to an eyepiece,

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Figure 8.7 Shikani Optical Stylet®. (Copyright image provided as courtesy of Clarus Medical, Minneapolis, MN.)

Figure 8.8 Levitan FPS Stylet. (Copyright image provided as courtesy of Clarus Medical, Minneapolis, MN.)

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allowing for visualization of the airway. As with the Shikani, the ETT is preloaded on the stylet. There is an adaptor “slide cone” for fixation of the ETT. This adaptor has a side port that allows oxygen insufflation or instillation of local anesthetic; thus, it can be used for awake intubation, if indicated. A similar device is the Brambrink Intubation Endoscope™ (Karl Storz Endoscopy; Tuttingen, Germany). It is different from the Bonfils in that it is semi-flexible.

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Video 8.4

Tracheal Intubation with the Bonfils Retromolar Intubation Fiberscope™

Intubation Technique With High-Resolution Optical Stylets These optical stylets allow for intubation either with direct/indirect laryngoscopy or without (solo technique). The left hand of the operator lifts the supine patient’s jaw by gently grasping the mandible and displacing it anteriorly to facilitate the insertion of the stylet (with a preloaded ETT) under the tongue to facilitate placement (Fig. 8.10). The tip of the scope should be visualized directly until it passes under the tongue. After visualizing the tip of the stylet pass through the cords (through the eyepiece or the monitor), the ETT can be advanced over the stylet into proper position. Insufflation of oxygen through the appropriate delivery system allows for the lens to remain clear from fogging and secretions, as well as to provide oxygenation. The advantage of performing direct laryngoscopy with these optical stylets is that there is no need for extreme head extension or forced traction of the laryngoscope blade to achieve a satisfactory view. All can be used for awake intubation. Advantages of these optical stylets over the conventional flexible FOB have been attributed to the preformed shape of these tools allowing for an easier maneuverability around the oropharyngeal structures, including a large, floppy epiglottis. This has been described for the nonmalleable Bonfils (fixed anterior tip curvature of 40°), as well as the malleable Shikani and Levitan (suggested straight-to-cuff shape of 35° bend angle). This shape also permits simultaneous visualization of the tube tip and target (glottic opening) under direct vision.

Figure 8.9 Bonfils Retromolar Intubation FiberscopeTM in various sizes. (Copyright image provided as courtesy of Karl Storz Endoscopy, Tuttingen, Germany.)

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Figure 8.10 Intubation technique with the Clarus Video System using a jaw lift.

Lighted Optical Stylet Tips • As for any airway device, skill should be obtained before their use. • Optimize visualization by suctioning the mouth and the posterior pharynx. • Pretreat the patient (whenever medically feasible) with an antisialagogue to reduce the production of secretions. • Avoid fogging of the lens by applying an anti-fogging agent or simply by dipping the tip of the stylet into warm water/saline. • To improve visualization of the glottis, the tongue may be gently pulled out of the mouth by grasping the tip with a piece of gauze. Neck extension and external jaw thrust can also help to increase the retromandibular space. • If the epiglottis is obstructing the view of the glottis, try inserting the tip of the stylet into the esophagus and withdrawing until the glottis comes into view. • To facilitate advancement of the ETT off the stylet, always ensure adequate lubrication and load the ETT onto the stylet with the beveled end facing medially. Use a twisting motion when sliding the ETT off the stylet.

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Hybrid Fiberoptic Video Stylets The SensaScope® (Acutronic; Hirzel, Switzerland) was first introduced into clinical practice in 2006 (Fig. 8.11). Described as a “new hybrid guidable semi-rigid video stylet” with a novel S-shaped curvature, the SensaScope is 45 cm long. A unique feature of this stylet is the 3 cm long steerable tip, which by operating a lever at the proximal end of the device can be flexed 75° in both directions on the sagittal plane. In addition, the proximal end holds a standard 15 mm shaft over which the ETT can be secured, an eyepiece that can be also connected to a video camera, and a light source connector. Although it does not have a working channel, oxygen can be supplied via the adapter that holds the ETT in place. Like the SensaScope®, the Video RIFL® Scope (AI Medical Devices, Williamston, MI) has a rigid portion and a flexible, steerable tip that can bend to 135°. An actuation lever that is grasped by the operator’s right hand allows steering of the tip (Fig. 8.12). It fits ETTs size 6.5 mm or larger. Powered solely by batteries, it provides a clear image that is displayed on the LCD monitor attached to the handle portion. Despite the overall structure of this stylet being quite bulky and heavy, the fact that the monitor for visualization is attached to the stylet could be an advantage in those situations when a difficult intubation is encountered outside of the operating room.

Intubation Technique With Hybrid Fiberoptic Video Stylets The SensaScope® is intended to facilitate intubation providing continuous vision of the anatomical structures during conventional direct laryngoscopy. The intubating technique with the SensaScope® requires the operator to first perform direct laryngoscopy with a Macintosh blade in the left hand and then to proceed to hold the stylet (with a preloaded ETT) in the right hand. The scope should be carefully advanced along the palate. Just as with the flexible FOB, the tip should be kept, at first, in a neutral position. Once the cords are visualized, the operator should lower the scope prior to advancing it into the trachea. Ultimately, under direct vision, the ETT can be positioned properly once the carina has been visualized. The Video RIFL®, like the SensaScope®, can be used as an aid to direct laryngoscopy. In this scenario, it shares the same technical points. Similarly to the high-resolution optical stylets, it also allows for intubation with a direct laryngoscope-free technique (refer to high-resolution optical stylets for intubation technique). In addition to providing continuous visualization of the airway structures during direct or indirect laryngoscopy, these stylets provide optimal visualization without the need for extreme head extension or forced traction of the laryngoscope blade. Because the utilization of SensaScope® is linked to direct laryngoscopy, one might presume that this stylet would also share some of the limitations of direct laryngoscopy, including the

Figure 8.11 SensaScope®. (Copyright image provided as courtesy of Acutronic, Hirzel, Switzerland.)

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Figure 8.12 Video RIFL® Scope. (Copyright image provided as courtesy of AI Medical Devices, Williamston, MI.)

need for a satisfactory mouth opening as well as a certain degree of cervical spine motion. Although this concept holds true to some extent, the SensaScope® has been successfully utilized to perform awake intubation in a limited number of patients presenting with a variety of difficult airway scenarios, including cervical spine instability. As these optical stylets are relatively recent and studies reporting their clinical application during difficult airway are still limited, flexible FOB remains the gold-standard technique in those patients who present with cervical spine instability or those who require awake intubation secondary to predicted difficult mask ventilation/ intubation.

Video RIFL® Tip • Make sure that the actuation lever of the Video RIFL® Scope is relaxed before removing the scope from the ETT.

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Suggested Reading Hodzovic I, Wilkes AR, Stacey M, Latto IP. Evaluation of clinical effectiveness of the Frova single-use tracheal tube introducer. Anaesthesia 2008;63:189–194. Hodzovic I, Latto IP, Wilkes AR, Hall JE, Mapleson WW. Evaluation of Frova, single-use intubation introducer, in a manikin. Comparison with Eschmann multiple-use introducer and Portex single-use introducer. Anaesthesia 2004;59:811–816. Hagberg CA. Current concepts in the management of the difficult airway. Anesthesiology News. 2009;35(10):85–104. Cook TM, Seller C, Gupta K, Thornton M, O’Sullivan E. Conventional uses of the Aintree Intubating Catheter in management of the difficult airway. Anaesthesia 2007;62:169–174. Higgs A, Clark E, Premraj K. Low-skill fibreoptic intubation: use of the Aintree Catheter with the classic LMA. Anaesthesia 2005;60:915–920. Rhee KY, Lee JR, Kim J, Park S, Kwon WK, Han S. A comparison of lighted stylet (Surch-Lite™) and direct laryngoscopic intubation in patients with high Mallampati scores. Anesth Analg 2009;108:1215–1219. Shikani AH. New “seeing” stylet-scope and method for the management of the difficult airway. Otolaryngol Head Neck Surg1999;120:113–116. Levitan RM. Design rationale and intended use of a short optical stylet for routine fiberoptic augmentation of emergency laryngoscopy. Am J of Emerg Med 2006;24:490–495. Abramson SI, Holmes AA, Hagberg CA. Awake insertion of the Bonfils retromolar intubation fiberscope in five patients with anticipated difficult airways. Anesth Analg 2008;106:1215–1217. Kovacs G, Law AJ, Petrie D. Awake fiberoptic intubation using an optical stylet in an anticipated difficult airway. Ann Emerg Med 2007;49:81–83. Biro P, Battig U, Henderson J, Seifert B. First clinical experience of tracheal intubation with the SensaScope®, a novel; steerable semirigid video stylet. Br J Anesth 2006;97:255–261. Greif R, Kleine-Brueggeney M, Theiler L. Awake tracheal intubation using the SensaScope® in 13 patients with an anticipated difficult airway. Anaesthesia 2010;65:525–528. Davis L, Cook-Sather SD, Schreiner MS. Lighted stylet tracheal intubation: a review. Anesth Analg. 2000;91(3):745–756. Langeron O, Birenbaum A, Amour J. Airway management in trauma. Minerva Anesthesiol. 2009;75(5):307–311.

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Chapter 9

Flexible Fiberoptic Intubation

Carlos A. Artime, MD

Objectives • Discuss the indications and advantages of flexible fiberoptic intubation. • Outline the steps that should be taken to prepare for a flexible fiberoptic intubation. • List the different steps involved in flexible fiberoptic intubation and how to troubleshoot when difficulties arise.

Introduction Fiberoptic-guided intubation of an anesthetized patient was first described in 1967 using a flexible fiberoptic choledochoscope. Since that time, fiberoptic technology has been developed specifically for the purpose of bronchoscopy and tracheal intubation, and the flexible fiberoptic bronchoscope (FOB) has become an invaluable tool in the airway management of both awake and anesthetized patients. There are countless clinical scenarios where fiberoptic intubation (FOI) provides a superior technique for airway management and it is well accepted that FOI of the awake, spontaneously ventilating patient is the “gold standard” for management of the difficult airway. Indications for FOI essentially include any indication for tracheal intubation. There are several clinical scenarios, however, where FOI may be the airway management technique of choice: • Known or anticipated difficult airway (“cannot intubate/cannot ventilate” [CICV]) • Extension of the neck is undesirable (e.g., unstable cervical fracture, severe cervical stenosis, vertebral artery insufficiency, or Chiari malformation) • High risk of dental damage (e.g., poor dentition or fragile dental work) • Mouth opening is limited (e.g., TMJ disease, mandibular-maxillary fixation, severe facial burns) There are no specific contraindications for FOI; however, in certain clinical situations, successful FOI is unlikely. Severe airway bleeding can obscure anatomical landmarks and soil the tip of the FOB with blood, making visualization of the larynx extremely difficult. Obstruction or severe stenosis of the airway such that a FOB cannot be passed can also make FOI impossible.

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98 • • • • • •

Fiberoptic intubation provides several advantages over standard airway management techniques: Allows for visual examination of the airway prior to intubation Provides confirmation of tube placement, avoiding esophageal and endobronchial intubation Eliminates the need for three-axis alignment; least likely method to result in cervical spine movement Well-tolerated in awake patients (less tachycardia and hypertension) Less potential for airway and dental trauma Can be performed in multiple positions

Equipment The standard FOB (Fig. 9.1) consists of thousands of flexible glass fibers approximately 8 μm to 10 μm in diameter that are capable of transmitting reflected light along their length. Light is transmitted via from an external light source to the distal end of the FOB; the light reflecting off the object to be viewed is transmitted back along the length of the FOB to an eyepiece or video camera at the proximal end of the scope. In recent years, FOBs have been replaced by modern bronchoscopes that use video chip technology. The Ambu® aScope™ 2 (Ambu, Copenhagen, Denmark) is a disposable, single-use flexible intubation scope that shares a similar design to video chip bronchoscopes (Fig. 9.2). The scope itself has a length of 63 cm, a 0.8 mm working channel (suitable for drug instillation but not suctioning), and can accommodate a 6.0 mm or larger endotracheal tube (ETT). The image is displayed on the portable aScope™ monitor. Specific advantages include the lack of cross-contamination risk and a decreased cost basis as compared to traditional FOBs, which incur maintenance and repair costs. Prior to its use, one must ensure that the FOB, light source, and video monitor (if being utilized) are in proper working condition and that all components have been fully prepared for use. This includes focusing the FOB, ensuring proper view orientation if using a video camera, lubricating the distal third of the FOB, applying anti-fogging solution to the tip of the FOB, and connecting a suction line or oxygen source to the suction port. The ETT should be prepared by placing it in a warm water bath. This softens the plastic, easing passage into the trachea and minimizing airway trauma. The ETT should then be lubricated prior to being loaded onto the FOB and secured with tape (Fig. 9.3). All other ancillary equipment needed for the planned technique, such as intubating airways, medications (e.g., lidocaine), and airway exchange catheters, should be readily available.

Working channel Light bundles

Epidural catheter Lens convering viewing bundle Diopter ring

Tracheal tube Flexible insertion cord Eye piece Control lever

Light cable Venting connector

Bending section To light source

Figure 9.1 A standard FOB. (From Miller RD, ed. Miller’s Anesthesia. 7th ed. 2009.)

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Figure 9.2 The Ambu® aScope™ 2. (Image courtesy of Ambu USA, Glen Burnie, MD.)

Flexible Fiberoptic Laryngoscopy Tips • Use a silicone-based lubricant for lubricating the FOB. Water-based lubricants can become sticky as they dry, whereas petroleum-based lubricants can damage the outer coating of the FOB. • Petroleum based-lubricants, such as lidocaine ointment or ophthalmic lubricant, can be used for lubricating the ETT. • Avoid getting lubricant on the tip of the FOB, as this can obscure the view. • To secure the ETT to the FOB, remove the 15 mm connector and tape the ETT directly to the scope (Fig. 9.3A). It is important to always place the connector in a safe place; the best location is attached to the circuit. • Alternatively, use the pilot balloon to tape the ETT onto the FOB (Fig. 9.3B).

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Figure 9.3 Use of the pilot balloon to tape the ETT onto the FOB.

Awake versus Asleep Fiberoptic Intubation Before proceeding with FOI, the decision must be made whether to perform the procedure before or after the induction of general anesthesia (GA). Indications for an awake FOI are generally those situations where mask ventilation is anticipated to be difficult, when there is a need for a postintubation neurologic exam, or when induction of GA could cause adverse hemodynamic or respiratory consequences. A comprehensive list of indications can be found in Chapter 2. The major technical disadvantage to performing FOI under GA is the loss of pharyngeal muscle tone, which can lead to upper airway collapse and difficult fiberoptic laryngoscopy.

Preparation of the Patient Prior to FOI, certain premedicants should be considered. Unless contraindicated, an antisialagogue, such as glycopyrrolate 0.2 mg IV, should be administered to dry airway secretions. In the patient at high risk for aspiration, prophylactic medications should be administered. For awake FOI, topical anesthesia of the airway is necessary, and in some circumstances, IV sedation may be appropriate. (See Chapter 2 for details.) Patient positioning for FOI primarily depends on the preference of the physician. Successful FOI can be accomplished in the supine or sitting/beach-chair positions. Emergency FOI in the lateral decubitus and prone positions have also been described. When performing FOI in the supine position, the physician stands at the head of the patient. Advantages to this position are that the laryngeal view through the FOB is in the same orientation as during direct laryngoscopy, and the patient and physician are already in the optimal position to perform mask ventilation or other airway maneuvers, if necessary. When performing FOI with the patient in the sitting or beach-chair position, the physician should stand facing the patient at the patient’s side. This position may be the position of choice in awake, non-sedated FOI because of improved ventilation and greater patient comfort. In addition, the sitting position optimizes airway anatomy and prevents airway collapse in obese patients, in patients with obstructive sleep apnea, and in patients with anterior extrinsic airway obstruction.

101 • When performing a FOI in the sitting position, stand on the side of the patient such that the hand that controls the insertion cord is closest to the patient. The fiberoptic cart should be positioned to the left of the physician (on the opposite side of the patient, if necessary).

Technique One of two approaches can be utilized for FOI: orotracheal and nasotracheal. While weighing the advantages and disadvantages, the clinician should determine which approach is best-suited for the clinical situation (Table 9.1). There are various techniques for FOI—which technique to use depends on whether the patient will be awake, sedated, spontaneously ventilating under GA, or under GA with muscle paralysis and whether the plan is for orotracheal or nasotracheal intubation. Whichever route the physician chooses, however, there are essentially two steps to FOI: 1. Performing fiberoptic laryngoscopy and endoscopy (obtaining a view of the glottis with the FOB and maneuvering the FOB through the vocal cords into the trachea). 2. Advancing the ETT over the FOB into its proper position in the trachea and removing the FOB. These steps will be discussed separately to address the specific issues that frequently arise during the procedure.

Table 9.1 Advantages and Disadvantages of Oral and Nasal Fiberoptic Intubation Advantages

Disadvantages

Orotracheal

• Less traumatic and lower risk of bleeding • Preferable for long-term intubation • Usually allows for placement of a larger ETT • Can be performed in patients with maxillary or skull base fractures

• More difficult fiberoptic technique • Stimulates the gag reflex; requires dense airway anesthesia • Risk of damage to the FOB by biting • Potentially less comfortable for the patient

Nasotracheal

• Easier view of the larynx • Bypasses the gag reflex • Does not require mouth opening • Prevents damage to the FOB by biting • Potentially more comfortable for the patient • Allows for intra-oral surgical procedures

• Usually requires a smaller ETT • Risk of trauma to nasal mucosa and/ or nasal turbinates • Risk of submucosal tunneling in the nasopharynx • Risk of epistaxis • Relatively contraindicated in setting of maxillary or skull base fractures

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Flexible Fiberoptic Laryngoscopy Tips • • • •

It is best to suction the oropharynx prior to inserting the FOB. Use a lens defogger or insert the tip of the FOB in warm saline prior to its use. If fogging occurs, touch the tip of the FOB to the airway mucosa to clear the view. If necessary, use O2 via the suction channel, but use low flows (2–3 L/min) and be able to identify where the tip of the FOB is at all times. Avoid this in pediatric patients and patients with severe airway obstruction, as this can lead to a build-up of pressure and potential barotrauma. • Supplemental O2 can also be administered over the patient’s nose or mouth, depending on the route of intubation.

Oral Fiberoptic Laryngoscopy One major challenge in oral FOI is navigating the FOB around the base of the tongue to achieve a satisfactory view of the larynx. The FOB has a tendency to stray off the midline and frequently there is little to no airspace between the tongue and the palate through which to navigate the FOB. To mitigate this issue, there are several devices or techniques that can be utilized. Specialized intubating oral airways are useful for several reasons: to protect the FOB from damage by biting, to prevent the tongue from falling back into the pharynx and obstructing the airspace, and to keep the FOB midline while guiding it to the larynx. There are several types available, each with unique design differences. They include the Ovassapian, Berman, and Williams airways (Figs. 9.4 and 9.5). A disadvantage of these devices is that they place pressure on the base of the tongue, potentially causing gagging in awake patients. ROTIGS™ (Rapid OroTracheal Intubation Guidance System; Hanu Surgical Devices, Honolulu, HI) is a novel device that has been developed to replace the endoscopic oral airway during awake oral FOI. ROTIGS™ is comprised of a mouthpiece, bite block, and guidance tube (Fig. 9.6). The mouthpiece and bite blocks keep the device centered and allow a midline approach to the larynx.

Figure 9.4 Berman, Williams, and Ovassapian airways.

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Figure 9.5 A flexible FOB inserted through a Bermann airway. (From Miller RD, ed. Miller’s Anesthesia. 7th ed. 2009.)

Figure 9.6 ROTIGS™ (Hanu Surgical Devices, Honolulu, HI).

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Because the device does not rest on the tongue, it does not cause gagging, making it well-suited for use in awake and minimally sedated patients.

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Video 9.1

Awake Fiberoptic Orotracheal Intubation using ROTIGS™

In both awake patients and those under GA, gentle traction on the tongue anteriorly is helpful in preventing the tongue from falling back into the pharynx if an intubating airway is not used. This can easily be accomplished by hand with the aid of 4” × 4”gauze pads for traction or with Magill forceps. Care should be taken to not injure the tongue on the bottom teeth. Laryngeal mask airways (LMAs) and intubating LMAs can both be used as conduits for oral FOI. (See Chapters 6 and 14 for details on these techniques.)

Flexible Fiberoptic Laryngoscopy Tips • When using an intubating oral airway, it is usually best to load the ETT in the oral airway first, as opposed to loading the ETT directly on the FOB. Insert the ETT to a depth of 5 cm into the oral airway. • When performing oral FOI on an awake patient without the use of an intubating oral airway, instruct the patient to phonate as you advance the FOB along the palate around the base of the tongue. This elevates the soft palate, lifting it off the tongue and providing more space through which to navigate the FOB. • A 4″ × 4″ gauze may be used to gently retract the tongue to open more space in the oropharynx, facilitating FOI. Care should be taken to not cause a laceration on the tongue with the bottom teeth. • When performing a FOI in a patient under GA, a jaw lift can be used to open the airway and generate more airspace in the hypopharynx through which to navigate the FOB. This requires the assistance of a second person. This technique is useful in oral or nasal FOI and can be performed with an intubating oral airway in place. • Alternatively, a jaw lift can be accomplished using the JED™ (LMA North America, San Diego, CA). JED™ (Jaw Elevation Device) is a noninvasive, hands-free device that maintains a patent airway by lifting the jaw and extending the neck. See Fig. 9.7.

Video 9.2

Asleep Fiberoptic Orotracheal Intubation using JED™

Nasal Fiberoptic Laryngoscopy Obtaining a laryngeal view during nasal FOI is often easier as compared to the oral approach, because the FOB stays midline and the tip of the FOB is usually directed at the glottis as it enters the oropharynx. The challenge in the nasal approach is usually related to placement of the ETT through the nasal passage into the nasopharynx. There are several steps that can be taken to increase the chances of success. 1. Select the more patent nostril. This can be accomplished by occluding each nostril separately and having the patient inhale—the patient will usually be able to inhale much more effectively through one of the nares. Alternatively, one can use the FOB to visualize the nasal passages and determine which is more patent. 2. Administer a nasal mucosal vasoconstrictor. Cocaine, phenylephrine, and oxymetazoline are acceptable agents. (See Chapter 2.)

Mallinckrodt ® Nasal RAE® or Hi-Lo® ETT*

Nasopharyngeal airway

Size/ID (mm)

OD (mm)

Size (French)

8.0

10.9

34

11.3

7.5

10.2

32

10.7

7.0

9.6

30

10.0

6.5

8.9

28

9.3

6.0

8.2

26

8.7

OD (mm)

*Nellcor Puritan Bennett; Boulder, CO ID = internal diameter; OD = outer diameter

3. Gage the degree of patency of the nasal passage. Soft plastic nasopharyngeal airways (nasal trumpets) can be used to determine the ETT size that will pass easily. A nasopharyngeal airway one size larger than the desired ETT should be used. For example, placement of a 32 Fr nasopharyngeal airway predicts easy passage of a 7.0 mm ID ETT. Table 9.2 lists the outer diameters of various ETT and nasopharyngeal airway sizes. 4. Place the ETT into the nasopharynx before the FOB. Insert the warmed, softened, lubricated ETT through the prepared nostril into the nasopharynx first, rather than placing the FOB first and attempting to insert the ETT over it. This avoids the situation where one has successfully navigated the FOB into the trachea but cannot intubate because the nasal passage is inadequate. The FOB can then be placed through the ETT into the oropharynx, taking care to ensure that the tip of the FOB goes through the distal end of the ETT and not through the Murphy eye. Once the FOB is in the oropharynx, the glottic structures should be visible in a majority of patients. If not, the ETT may have been advanced too far into the oropharynx; withdraw the ETT slightly and look anteriorly. In heavily sedated patients or patients under GA, airway collapse may obscure the view of the glottis; the previously described techniques of tongue traction, jaw thrust, or neck extension can open the airway.

Flexible Fiberoptic Laryngoscopy Tip • It is important to not advance the ETT too far into the oropharynx, as this can make visualization of the vocal cords more difficult. A depth of 13 cm to 15 cm from the naris is usually adequate.

Fiberoptic Endoscopy Once the FOB has been successfully positioned in the oropharynx, the epiglottis and vocal cords can usually be visualized with a slight anterior deflection of the tip of the FOB. If only the epiglottis is visible, then maneuver the FOB below the epiglottis and flex the tip anteriorly to visualize the vocal cords. Aim for the anterior commissure of the vocal cords and flex posteriorly to enter into the trachea. The trachea is easily identifiable by the presence of the cartilaginous tracheal rings.

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Table 9.2 Outer Diameters of Various ETT and Nasopharyngeal Airway Sizes

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Figure 9.7 JED™ (LMA North America, San Diego, CA) can be used to facilitate asleep FOI. (Image courtesy of LMA North America, San Diego, CA.)

Advance the FOB distally until a point just above the carina. In some cases, glottic visualization is possible, but the FOB is unable to be advanced through the vocal cords despite all the “tricks” described because of abnormal anatomy or an obstructing lesion in the airway. In these situations, a guide wire can be utilized. In this technique, the FOB tip is moved as closely as possible to the vocal cords. A guide wire (such as one from a retrograde intubation kit) can then be fed into the working channel of the FOB and inserted through the vocal cords in an anterograde fashion. The FOB is then advanced over the guide wire into the trachea.

Flexible Fiberoptic Laryngoscopy Tips • Do not hesitate to use external laryngeal manipulation to bring the glottis into view. • In case of a long, floppy epiglottis, use neck extension, jaw lift, or traction on the tongue to bring the vocal cords into view. • Sometimes, insertion of a laryngoscope blade is necessary to open the airspace and lift the epiglottis off the posterior pharyngeal wall. • Another trick for difficult fiberoptic laryngoscopy is to advance the FOB into the esophagus, flex the tip of the FOB anteriorly about 75°, and retract slowly. As soon as the FOB

Advancing the Endotracheal Tube Over the Fiberoptic Bronchoscope Once the FOB has been positioned just above the carina in the trachea, the ETT is advanced over the FOB while continuously visualizing the trachea through the FOB. This provides confirmation that the FOB and ETT have not been accidentally dislodged into the oropharynx or esophagus. Frequently, especially with orotracheal intubation, resistance is met as the tip of ETT reaches the glottic inlet. Studies have shown that this usually results from the bevel of the ETT impinging on the right arytenoid. A slight withdrawal of the ETT and a 90° turn counterclockwise, orienting the bevel posteriorly, usually resolves this issue. For nasotracheal intubation, a clockwise 90° turn such that the bevel is oriented anteriorly can prevent the tip of the ETT impinging on the epiglottis. Alternatively, the Parker Flex-TipTM ETT (Parker Medical, Englewood, CO), which has a bull-nosed tip directed toward the center of the distal lumen, can be utilized (Fig. 9.8). This ETT has been shown to have a higher first-pass success rate when being advanced over a FOB. Parker Flex-Tip® Tube

No gap between tip of Parker tube and FOB. Figure 9.8 The Parker Flex-TipTM ETT. (Image courtesy of Parker Medical, Highlands Ranch, CO.)

Standard ETT

Gap between leading edge of stardard ETT and FOB. This gap allows the projecting tube edge to catch on the arytenoid cartilage as the tube is advanced into the glottis.

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107 exits the esophagus, the tip of the FOB should be underneath the epiglottis, and some slight maneuvering should bring the vocal cords into view. • If the patient is awake, then changing position to sitting or lateral can improve glottic visualization. One can also ask the patient to sniff, swallow, or inhale deeply to aid in maneuvering the FOB through the vocal cords. • If the patient is spontaneously ventilating (either awake or under GA), spray 2 mL of 4% lidocaine through the working channel of the FOB prior to advancing through the vocal cords to avoid laryngospasm. Laryngotracheal anesthesia can also be administered through an epidural catheter inserted through the working channel of the FOB. (These techniques are usually unnecessary if a transtracheal block has been performed.)

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Upon successful passage of the ETT, proper depth (2–3 cm from the carina) is confirmed during withdrawal of the FOB. If indicated, a neurologic examination is performed. After confirmation of the presence of end-tidal CO2 on the capnogram, anesthesia is induced with a rapid intravenous agent. On rare occasion, the FOB may prove difficult to remove from the ETT. This may result from the FOB having passed through the Murphy eye rather than the distal lumen or could be a result of inadequate lubrication of the FOB. In these situations, forceful removal may damage the instrument; therefore, the FOB and ETT should be removed as a unit and the procedure repeated.

Flexible Fiberoptic Intubation Tips • NEVER use force when advancing the ETT over the FOB. • A warmed, softened ETT will usually pass through the vocal cords more easily and with less trauma. • A flexometallic ETT or the tapered-tip ETT for use with the intubating LMA can be used for FOI to increase the chance of first-pass success when railroading over a FOB if a Parker Flex-TipTM ETT is not available. • Many times, the gap between the FOB and the larger ETT is a factor when difficulty is encountered advancing the ETT into the trachea. An Aintree catheter loaded in between the FOB and the ETT can minimize this gap and increase success in advancing the ETT over the FOB.

Summary Flexible fiberoptic intubation is a valuable technique for airway management and the gold standard for management of most difficult airways. All practitioners involved in airway management should be familiar with the difficulties that may arise during the procedure and the steps that can be taken to overcome them.

Suggested Reading Gil KSL, Demunsch PA. Fiberoptic and flexible-endoscopy aided technique. In: Hagberg CA, ed. Benumof’s Airway Management, 3rd ed. Philadelphia, PA: Mosby; 2012:365–411. Popat M. Practical Fibreoptic Intubation. Oxford: Butterworth Heinemann; 2001. Ovassapian A. Fiberoptic Endoscopy and the Difficult Airway. Philadelphia, PA: Lippincott-Raven; 1996. Benumof JL. Management of the difficult adult airway. Anesthesiology 1991;75:1087–1110. Asai T, Shingu K. Difficulty in advancing a tracheal tube over a fibreoptic bronchoscope: incidence, causes and solutions. Br J Anaesth. 2004;92(6):870–881.

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Chapter 10

Retrograde Intubation

Katherine C. Normand, MD and A. Paul Aucoin, MD

Objectives • Discuss the indications and contraindications for retrograde intubation. • Review the relevant anatomy for retrograde intubation. • Learn the different techniques for retrograde intubation.

Introduction Retrograde intubation (RI) is a well-described technique that involves several methods of translaryngeal guided nonsurgical airway access to assist in endotracheal or nasotracheal intubation. It can be used successfully in awake, sedated, obtunded, or apneic patients who have either an anticipated or unanticipated difficult airway. Butler and Cirillo reported the first case of RI in 1960. They passed a red rubber catheter cephalad through a patient’s existing tracheostomy. After the catheter exited the patient’s mouth, it was tied to an endotracheal tube (ETT), which was then pulled into the patient’s trachea. The term retrograde intubation is a misnomer; the technique is actually a translaryngeal-guided intubation. The ASA Practice Guidelines on Management of the Difficult Airway describe RI as an alternative approach to difficult intubation. Retrograde intubation is included in the ASA Difficult Airway Algorithm in the nonemergent pathway, when unable to intubate but able to ventilate. The ASA Difficult Airway Task Force suggests that equipment for RI be included in a portable storage unit for difficult airway management. Retrograde intubation can take several minutes to accomplish; therefore, it is not appropriate to use in an emergent “cannot ventilate, cannot intubate” scenario.

Indications Retrograde intubation has been used in a variety of airway pathologies. It can be employed in both adult and pediatric patients and has even been used in neonates as young as 1 day old. Indications include: failure of direct laryngoscopy; obstruction of a view of the vocal cords by

blood, secretions, or anatomic derangement; and difficult intubation scenarios such as unstable cervical spine, ankylosing spondylitis, maxillofacial trauma, or trismus. Retrograde intubation is also an alternative to fiberoptic intubation in developing countries where the availability of flexible fiberoptic bronchoscopes is limited.

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Retrograde Intubation Tips • Retrograde intubation can be performed in an awake patient when spontaneous ventilation is necessary. Proper anesthetizing of the airway must be performed before the RI is initiated. • Retrograde intubation is beneficial in the unexpected difficult airway in which multiple direct laryngoscopies have caused trauma and fiberoptic intubation may be difficult to perform secondary to bleeding. • Retrograde intubation can be performed during bag mask ventilation or with an LMA in place. The LMA should be removed as the wire is advanced.

Contraindications This technique is contraindicated if ventilation (spontaneous or positive pressure) is not possible. Additional contraindications to RI are mostly relative and can be divided into four categories: difficult anatomy, laryngotracheal disease, coagulopathy, and infection. • Difficult anatomy: RI is performed at or below the level of the cricoid cartilage; therefore, this anatomy should be accessible. A severe flexion deformity of the cervical spine can make RI unfeasible. Patients with nonpalpable anatomical landmarks, overlying malignancy, or a goiter should be approached cautiously. • Laryngotracheal disease: Narrowing of the trachea or larynx can be made worse by needle puncture or catheter insertion. Retrograde intubation should be avoided when tracheal stenosis exists directly under the puncture site. • Coagulopathy: Although the cricothyroid membrane (CTM) is a relatively avascular structure, preexisting bleeding diathesis should be considered a relative contraindication. • Infection: An infection over the puncture site or the path of the puncture can result in spread of the bacteria into the trachea and should be avoided.

Complications 1. 2. 3. 4. 5. 6. 7.

Bleeding (usually minimal) Subcutaneous emphysema Pneumomediastinum Pneumothorax Pretracheal abscess (late complication, more common in diabetic patients) Hypercapnia secondary to periods of apnea Injury to posterior trachea and esophagus

Anatomy The performance of RI requires knowledge of the anatomy of the cricoid cartilage and surrounding structures (Fig. 10.1). The cricoid cartilage is a ring-shaped structure inferior to the thyroid

Thyroid cartilage Cricothyroid membrane Cricoid cartilage

Figure 10.1 Relevant anatomy for retrograde intubation. The puncture site is the lower third of the CTM, just above the cricoid cartilage. (From Walls RM, Murphy MF, eds. Manual of Emergency Airway Management. Philadelphia, PA: Lippincott Williams & Wilkins; 2000.)

cartilage that can be palpated on the anterior neck as a firm, rounded structure 1.5 to 2 fingerbreadths inferior to the laryngeal prominence (Adam’s apple or thyroid notch). The CTM is a relatively avascular, elastic tissue extending from the thyroid cartilage superiorly to the cricoid cartilage inferiorly. It is approximately 1 cm in height and 2 cm in width. It can be identified as a shallow groove between the cricoid cartilage and the inferior border of the thyroid cartilage. The cricothyroid artery runs along the anterior surface of the CTM, close to the thyroid cartilage.

Retrograde Intubation Tip • Because of the location of the cricothyroid artery and the proximity of the CTM to the vocal folds, puncture of the CTM should be made in the inferior third of the membrane and directed posteriorly.

Technique 1. Positioning: Ideally, the patient should be in the supine sniffing position with the neck in hyperextension, allowing easier palpation of the cricoid cartilage and surrounding structures. Retrograde intubation can also be performed with the patient in the sitting position or with the neck in a neutral position (e.g., in a patient with cervical spine injury or limited range of motion of the neck). 2. Skin preparation: The anterior neck should be cleansed prior to puncture. Retrograde intubation should be performed using aseptic technique. It has been suggested that prophylactic antibiotics be administered to diabetic or immunocompromised patients prior to the performance of an elective RI.

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3. Anesthesia: For the patient undergoing awake or sedated RI, several different techniques can be used to prevent discomfort during the procedure, including transtracheal anesthesia, superior laryngeal nerve block, and topicalization of the airway mucosa with atomized or nebulized local anesthetic (see Chapter 2). For the patient under general anesthesia, instillation of translaryngeal local anesthetic after CTM puncture can reduce the incidence of sympathetic stimulation and laryngospasm. 4. Entry site: The translaryngeal puncture site can be performed superior or inferior to the cricoid cartilage. The CTM (superior to the cricoid cartilage) has the advantage of being relatively avascular; however, a puncture at this site allows only 1 cm of space below the level of the vocal cords for the tip of the ETT. A puncture site inferior to the cricoid cartilage, at the cricotracheal ligament, allows the ETT to travel in a straighter path with a longer length of the ETT below the vocal cords; however, this site is associated with a greater potential for bleeding.

Retrograde Intubation Tip • Retrograde intubation can take several minutes to perform (depending on operator experience and patient anatomy), so ventilation of a patient is necessary while the procedure is being performed. Patients with a reduced FRC (e.g., the morbidly obese) may not be good candidates for RI secondary to a limited ability to withstand periods of apnea.

Classic Technique This technique requires a standard 17 g Tuohy needle, a syringe half-filled with saline, a hemostat, and a standard epidural catheter. 1. After the patient has been positioned and the skin has been properly cleansed, a right-hand-dominant person should stand on the patient’s right side. 2. Use the left hand to stabilize the trachea by placing the thumb and the third digit of either side of the thyroid cartilage. The index finger of the left hand identifies the midline of the CTM and the upper border of the cricoid cartilage. 3. With the right hand, grasp the Tuohy needle with the saline-filled syringe like a pencil, and puncture the CTM, aspirating to confirm placement in the lumen of the airway. The bevel of the Tuohy needle must be directed cephalad. 4. Once the Tuohy needle is in the trachea, remove the syringe and insert an epidural catheter through the needle until it exits the oral or nasal cavity. It is important to pull the tongue anteriorly to prevent the catheter from coiling in the oropharynx. 5. Clamp the epidural catheter with a hemostat at the neck skin line to prevent further movement of the epidural catheter. 6. Thread the epidural catheter through the Murphy eye (outside to inside) or through the distal lumen of the ETT. 7. Advance the ETT over the epidural catheter into the trachea. 8. Verify that the ETT is below the vocal cords before removing the epidural catheter by the presence of bilateral breath sounds and by capnography. Fiberoptic bronchoscopy can also be utilized to confirm proper ETT positioning.

113 • Because the Tuohy needle is blunt, make a small incision with a blade or a large-bore cutting needle at the selected puncture site to facilitate advancing the Tuohy through the skin. A skin incision may not be necessary if the neck skin is very thin. • Rather than saline, fill the syringe with 1% to 2% lidocaine and inject the local anesthetic after placement of the tip of the needle in the lumen of the trachea is confirmed. This provides additional anesthesia to blunt the sympathetic response and prevent laryngospasm.

Guidewire Technique Performing a RI with a J-tip guidewire rather than an epidural catheter provides the following advantages: the J-tip of a guidewire is less traumatic to airway; there is less tendency for the guidewire to coil or kink; retrieval of the guidewire from the oral or nasal cavity is easier; the guidewire can be used in conjunction with a fiberoptic bronchoscope; and it is a faster technique. This technique requires an 18 g angiocatheter, a syringe half-filled with saline, a J-tip guidewire, a guide catheter (e.g., an Arndt Airway Exchange Catheter), and a hemostat. The discrepancy in diameter between the guidewire and ETT predisposes the ETT to catch on the arytenoids or vocal cords rather than sliding smoothly into the trachea. The guide catheter reduces this discrepancy in diameter and can prevent this from occurring. 1. After the patient has been positioned and the skin has been properly cleansed, a right-hand-dominant person should stand on the patient’s right side. 2. Use the left hand to stabilize the trachea by placing the thumb and the third digit of either side of the thyroid cartilage. The index finger of the left hand identifies the midline of the CTM and the upper border of the cricoid cartilage. 3. Attach the saline-filled syringe to the angiocatheter and advance at a 90° angle to the CTM, aspirating for air to confirm the position inside the trachea. (See Fig. 10.2A.) 4. Lower the angle to 45°, again aspirating air to confirm the position within the trachea. Remove the needle. 5. Advance the guidewire through the angiocatheter until it exits the mouth or nose (Fig. 10.2B). 6. Clamp the guidewire with a hemostat at the neck skinline. 7. Place the guide catheter over the portion of the guidewire exiting the oral or nasal cavity and advance it to the CTM (Fig. 10.2C). 8. Remove the wire. The guide catheter is now situated in the trachea. 9. Place the ETT over the guide catheter and advance the ETT through the vocal cords (Fig. 10.2D). 10. Remove the guide catheter and confirm proper endotracheal tube placement (Fig. 10.2E). Video 10.1

Guidewire-assisted Retrograde Intubation

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Tips

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(A)

(B)

(C)

(D)

(E)

Figure 10.2 The guidewire technique for retrograde intubation. (Courtesy of Cook Critical Care; Bloomington, IN).

115 • This technique ideally requires two individuals, one to place the transtracheal wire and another to mask ventilate and retrieve the guidewire. It is also helpful for one individual to maintain traction on the guidewire while the other individual advances the exchange catheter. • In patients with normal upper airway anatomy, the guidewire generally exits via the nose. If oropharyngeal placement is desired, then a hemostat may be needed to grasp and retrieve the guidewire from the oral cavity. Direct laryngoscopy during wire insertion can be helpful in guiding the wire toward the oral cavity. • One can add fiberoptic bronchoscopy to the guidewire technique by feeding the guidewire through the suction port of a fiberoptic bronchoscope. The ETT can then be loaded on the bronchoscope and advanced through the glottis after visual confirmation of guidewire placement in the trachea. • Push the wire in from the skin instead of pulling it once it is out of the mouth/nose. Pulling the wire can cause a slicing injury to the pharynx or tongue. • Tension must be maintained on the guidewire when removing it so that the exchange catheter does not “pop out” of the airway. • If the patient is hypoxic, then jet ventilation can be performed through the exchange catheter before placement of the ETT.

Commercially Available Kit Cook Medical currently has a commercially available retrograde intubation set. This is a complete set with all of the equipment necessary to perform a RI over a guidewire. It is available in two sizes (6 Fr and 14 Fr) and includes an Arndt Airway Exchange Catheter, which facilitates placement of an ETT, along with two Rapi-Fit® adapters, which allow for patient oxygenation through the exchange catheter if necessary.

Retrograde Intubation Tip • If using the Cook retrograde intubation kit, the guidewire is marked with two black lines that indicate the length of the exchange catheter. The guidewire should be advanced through the CTM until the second black line has reached the skin. The wire should be advanced one more centimeter and clamped with a set of hemostats. This will allow for visualization of the first black line 1 cm past the exchange catheter.

Suggested Reading 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 2003;98:1269–1277. Sanchez A. Retrograde Intubation Techniques. In: Hagberg CA, ed. Benumof’s Airway Management, 3rd ed. Philadelphia, PA: Mosby; 2012:412–429. Rosenblatt W. Airway Management. In: Barash PG, Cullen BF, Stoelting RK, eds. Clinical Anesthesia, 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005:595–642.

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Bagam K, Murthy SGK, Vikramaditya C, Jagadeesh V. Retrograde intubation: An alternative in difficult airway management in the absence of a fiberoptic laryngoscope. Indian J Anaesth 2010;54(6):585. Bowes WA, Johnson JO. Pneumomediastinum after planned retrograde fiberoptic intubation. Anesth Analg 1994;78:795–797. Hagberg CA. Current concepts in the management of the difficult airway. Anesthesiology News 2009;35(10):85–104.

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Chapter 11

Percutaneous Transtracheal Jet Ventilation Katherine C. Normand, MD

Objectives • Discuss the indications and contraindications for transtracheal jet ventilation. • Review the relevant anatomy for transtracheal jet ventilation. • Learn the techniques for transtracheal jet ventilation.

Introduction Percutaneous transtracheal jet ventilation (TTJV) is a relatively safe, quick, and effective method of oxygenation and ventilation in the “cannot intubate, cannot ventilate” (CICV) scenario when more conservative measures fail. The ASA Difficult Airway Algorithm lists TTJV as an emergent nonsurgical technique to be used in patients who cannot be conventionally ventilated or intubated. Transtracheal jet ventilation is widely regarded as a lifesaving procedure that can provide adequate, temporary oxygenation and ventilation with less training and complications than a surgical airway, a last resort for obtaining an airway in the algorithm. Flory et al. introduced TTJV in the 1950s, and by the 1970s, TTJV was being used as an airway management tool during routine surgical procedures of less than 2 hours. Currently, its primary use is as an emergency airway and, occasionally, for laryngeal surgery. The recommended time that this technique should be used is less than 30 minutes.

Mechanism of Transtracheal Jet Ventilation Inspiration during TTJV is achieved by insufflation of pressurized oxygen through a cannula. Expiration is passive because of the elastic recoil of the lungs and the chest wall. It is imperative that sufficient time is allowed for the passive expiration to avoid barotrauma from breath stacking. Expiration occurs through the glottis and depends on a nonobstructed upper airway, which is imperative to avoid barotrauma and resulting pneumothorax. The egress of air through the glottic aperture can also provide bubbles to facilitate placement of an endotracheal tube (ETT) when the

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glottic opening had not previously been able to be visualized. In fact, several case reports have demonstrated that after initiation of TTJV in an airway with little or no visualization of the glottis, successful intubation occurred because of opening of the glottis and guidance from bubbles with jet ventilation.

Indications for Transtracheal Jet Ventilation As previously mentioned, TTJV is indicated as an emergency technique for the establishment of oxygenation and ventilation in the CICV scenario. Other clinical situations where TTJV might be utilized include: 1. Combative or uncooperative patients with upper airway, facial, or head and neck trauma. Transtracheal jet ventilation can provide a quick, relatively painless airway to proceed with sedation to allow for a surgical airway. 2. Patients with copious oropharyngeal secretions that would render fiberoptic intubation difficult. Transtracheal jet ventilation can force the secretions out of the proximal trachea. 3. Patients with foreign bodies in the proximal trachea, in which placement of an ETT would cause further migration of the foreign body into the airway. Transtracheal jet ventilation in this situation may result in expulsion of the foreign body from the trachea. 4. Anatomic abnormalities that make an oral approach to airway management difficult, such as tumors of the glottis or base of the tongue. 5. Emergency airway in children less than 12 years old. Because of the small caliber of the trachea at the level of the cricoid membrane in this population, cricothyrotomy can be dangerous. 6. For inexperienced physicians, TTJV may be preferred over more difficult maneuvers (such as cricothyrotomy or fiberoptic intubation) in an already hypoxic patient because of the length of time involved.

Contraindications to Transtracheal Jet Ventilation Transtracheal jet ventilation should not be performed in patients who have sustained direct damage to the cricoid cartilage or larynx or in patients with complete upper airway obstruction. Surgical cricothyrotomy is preferred in these situations. Relative contraindications to TTJV include: 1. Partial airway obstruction in which air egress might not be possible. A smaller-sized catheter may be considered. 2. Distorted or difficult airway anatomy in which catheter placement might be difficult. 3. Uncorrected coagulopathy. 4. Obstructive pulmonary diseases, such as chronic bronchitis, asthma, or emphysema, which may increase the risk of barotrauma and pneumothorax. One recent study, however, showed that patients with chronic obstructive disease did not, in fact, have a higher incidence of barotrauma as a result of TTJV.

Complications of Transtracheal Jet Ventilation Although TTJV is considered a safe procedure—especially in comparison to the risks of a surgical airway—there does exist a risk of life-threatening complications. A major concern for TTJV is barotrauma with resulting pneumothorax from the use of high-pressure oxygen. To prevent this

Transtracheal Jet Ventilation Tip • If possible, use a kink-resistant catheter. Because of their thin walls, standard IV angiocatheters are highly prone to kinking, which can result in subcutaneous emphysema. • Be highly aware of the possibility for pneumothorax and have a low threshold for chest tube placement once TTJV is initiated.

Anatomy To perform TTJV safely, a firm understanding and knowledge of the anatomy is essential. The jet ventilation catheter is placed through the cricothyroid membrane (CTM) located in the anterior neck (Fig. 11.1). It is a ligament that is generally 8 mm to 12 mm in height with a width of 20 mm to 24 mm. It is avascular, made up of mostly elastic tissue. It is located between the thyroid cartilage superiorly and the cricoid cartilage inferiorly. To locate it, palpate the laryngeal prominence of the thyroid cartilage (Adam’s apple), then follow this down until an indentation is felt, which is the CTM. Commonly, small cricothyroid arteries cross the upper CTM, so it is important to perform TTJV in the lower third of the membrane, if possible.

Transtracheal Jet Ventilation Tip • If the laryngeal prominence cannot be located because of distortion of the airway, the suprasternal notch may be identified and, by walking up the trachea, the CTM may then be located. The CTM is generally located 3 fingerbreadths above the suprasternal notch with the neck in the neutral position.

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complication, it is an absolute necessity to ensure that a path for air egress exists and that there is adequate time for passive expiration. The lowest possible pressure that will provide adequate oxygenation and ventilation should be used. Other complications associated with TTJV include: 1. Subcutaneous or mediastinal emphysema resulting from catheter misplacement. It is critical to confirm catheter placement after needle removal to ensure correct placement. Initiation of high-pressure jet ventilation in a space other than the trachea will result in air being forced into the surrounding tissues. 2. Perforation of the posterior wall of the trachea or esophagus. Care must be taken when advancing the needle after puncture of the cricothyroid membrane to avoid lacerations and injuries to these structures. 3. Kinking of the catheter. Regular angiocatheters are prone to kinking because of their thin wall. It is best to use a kink-resistant catheter for TTJV. 4. Hemorrhage at the insertion site. This is generally rare if the cricothyroid membrane is properly identified, as it is avascular and no surgical incisions are performed. 5. Aspiration. Transtracheal jet ventilation does not prevent airway aspiration of secretions, blood, or gastric contents.

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Hyoid

Thyroid

Thyrohyoid membrane

Cricothyroid membrane— puncture site Thyroid gland isthmus Trachea

Figure 11.1. Anatomic landmarks for TTJV. (From Brown D, ed. Atlas of Regional Anesthesia, 2nd ed. Philadelphia, PA: Saunders; 1999.)

Technique Prior to initiating TTJV, all necessary equipment should be assembled and ready. Pre-assembled kits that contain the equipment are available, but in general the following items should be available: high-pressure non-collapsible tubing, a 12 g to 16 g kink-resistant catheter, a fluid-filled syringe, an oxygen source with a flow of 10 L/min to 15 L/min, and a manual jet ventilator/insufflator device. 1. Whenever possible, sterile techniques should be utilized. 2. Identify the CTM. 3. Attach a syringe containing partially filled saline to the large bore needle. Using the dominant hand, aim the needle caudally at a 30° to 45° angle at the skin. Stabilize the cricoid cartilage with the nondominant hand (Fig. 11.2A). 4. While aspirating, insert the needle through the skin, soft tissue, and CTM (Fig. 11.2B). 5. When air is freely aspirated, advance only the cannula and remove the needle. The needle should not be advanced, as it can perforate the posterior trachea or esophagus. 6. Reconfirm catheter placement by reattaching the fluid-filled syringe to the cannula and aspirating. 7. Secure the cannula with sutures or ties or, preferably, have someone dedicated to manually hold the cannula in place. 8. Connect the oxygen source to the cannula. 9. Administer oxygen via intermittent bursts (2 years

Size (mm ID) 2.5 3.0 3.0–3.5 4.0–4.5 (Age in years)/4 + 4 = ID

ETT Size and Depth Tips • For cuffed ETTs, subtract 0.5 mm from the ID. • For proper insertion depth for an orotracheal intubation, use the following formula: º (Age in years)/2 + 12 or º 3 × ID (mm) • Add 2 cm to the orotracheal insertion depth for a nasotracheal intubation.

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Double-lumen tubes are not available for use in pediatric patients younger than ages 6 years to 8 years. The Arndt Endobronchial Blocker (Cook Critical Care, Bloomington, IN) has been used to provide one-lung ventilation in infants. Some complications of endotracheal intubation include airway trauma, bleeding, and postintubation croup (incidence of 0.1%–1%). Subglottic stenosis can result from prolonged intubation because of mucosal ischemic injury secondary to the lateral wall pressure from the ETT; granulation tissue forms within 48 hours leading to scarring and stenosis.

Endotracheal Tube Exchangers Endotracheal tube exchangers have multiple uses; they can be used to exchange damaged ETTs and provide a conduit for reintubation, if necessary. The Frova Intubating Introducer (Cook Critical Care, Bloomington, IN) is available in a pediatric size (8 Fr) that allows placement of a 3.0 mm ETT. Cook also manufactures airway exchange catheters in four sizes. These catheters are hollow, blunt-tipped, and have distal side ports. The 8 Fr size is 45 cm in length and can be used in ETTs 3.0 mm or larger.

Laryngoscope Blades Straight laryngoscope blades are often recommended for use in neonates and infants to lift the epiglottis. The most common straight blades include the Miller, Wisconsin, Wis-Hipple, and Wis-Foregger blades. Curved blades are also available for use; they are more suitable for older children.

Bullard Laryngoscope The Bullard laryngoscope (ACMI Corporation, Southborough, MA) is an indirect laryngoscope that utilizes fiberoptic and mirror technology to visualize the larynx. Use of fiberoptics and a curved blade enable visualization of the larynx “around the corner” of the blade, thus eliminating the need to align the oral, pharyngeal, and laryngeal axes. A standard laryngoscope handle or a flexible fiberoptic cable connected to a light source powers the fiberoptic light source. This laryngoscope is manufactured in three sizes: adult, pediatric, and pediatric long. The adult size, with a blade that is 2.5 cm wide, is suitable for children older than age 10 years. The pediatric version has a blade 1.3 cm wide that extends 0.6 cm beyond the fiberoptics. This blade is recommended for use in neonates, infants, and smaller children. The pediatric long version is available for use in infants and small children up to age 10 years; it has a longer blade (1.4 cm) and a wider flange (1.6 cm). In the pediatric long version, a multifunctional stylet is attached to the fiberoptic bundle between the eyepiece and handle and aligns the tip of the ETT beneath the flange of the blade. The smallest ETT that passes over the stylet in the pediatric long version is 4.5 mm. The Bullard laryngoscope requires minimal mouth opening for its insertion (0.64 cm in cephalad-caudad axis). It has been used to intubate patients with unstable cervical spine or with Pierre-Robin, Treacher-Collins, Noonan’s, and Klippel-Feil syndrome, among others. The adult Bullard laryngoscope has been used successfully to intubate patients older than 12 months with normal airways.

Truview PCD The Truview PCD (Truphatek International, Netanya, Israel) is a recently introduced rigid laryngoscope that has an angulated tip and an optical assembly that provides an illuminated and magnified view of the larynx (see Fig. 15.3). It has been shown to improve laryngoscopic views in infants and children when compared to direct laryngoscopy with a Miller blade.

Figure 15.3 The Truview PCD (Truphatek International, Netanya, Israel).

Laryngeal Mask Airway Pediatric versions of the Laryngeal Mask Airway (LMA) ClassicTM, as well as the disposable LMA, are available for use and are part of the pediatric DA algorithm. This device requires minimal training and has been shown to be useful in neonatal resuscitation. The LMA has been described as a conduit for blind intubation as well as a conduit for fiberoptic intubation.

Induction and Airway Management Techniques The principles outlined in the ASA Guidelines for DA Management apply to the pediatric patient as well. Evaluation, recognition, and preparation are key elements. A surgeon capable of establishing a surgical airway and emergency airway equipment should be in the operating room before induction of anesthesia of the pediatric patient with a documented DA. A capable assistant should be available for help to induce anesthesia, insert an intravenous line, and help secure the airway. Infants and children are not as cooperative as adults; most alternative strategies are not successful in the awake pediatric patient. The history and physical examination may indicate situations in which direct laryngoscopy will be unsuccessful, and one should proceed directly to an alternative strategy for managing the airway. If an intravenous line is present, then intravenous induction can be performed after appropriate pre-oxygenation. Once the child is unconscious and the ability to mask ventilate is confirmed, neuromuscular blockade can facilitate direct laryngoscopy and intubation. If the infant or child does not have an intravenous line, inhalational induction should be performed with sevoflurane and oxygen. As soon as the child is unconscious, an intravenous line should be established. If it is easy to ventilate the infant or child with a mask, neuromuscular blockers might make laryngoscopy and intubation easier. Often, a properly placed shoulder roll can facilitate direct laryngoscopy and intubation. If the practitioner is unable to mask ventilate, then he/should call for immediate help and, if possible, insert an LMA or another supraglottic airway device. If unable to oxygenate with the LMA, then it may be necessary to awaken the patient or proceed with a surgical airway. An LMA should always be available when attempting to manage the airway of any pediatric patient, particularly one with a DA. An LMA may provide a way to successfully ventilate and oxygenate the patient at any time during intubation attempts to intubate and can provide an excellent channel for fiberoptic intubation. It may also be the only way to maintain an airway until a surgical airway is established or until the patient awakens. Fiberoptic intubation at this point may be difficult if there is already blood in the airway from multiple attempts at direct laryngoscopy. If blood or edema has made it difficult to intubate the patient and the surgery is elective, then it

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may be better to awaken the patient, reschedule the surgery, and plan for an alternative strategy for intubation from the beginning. Many other options are available to manage the difficult pediatric airway, such as the Bullard laryngoscope, transtracheal jet ventilation, retrograde intubation, and transcutaneous cricothyrotomy. Cannula cricothyrotomy in infants and children has high incidence of complications and, therefore, should not be used as an emergency adjunct in patients younger than age 5 to 6 years. The trachea of infants and small children is pencil-sized, elastic, flaccid, mobile, difficult to locate, and collapses if transcutaneous insertion is performed. Anatomically, the close approximation of the cricoid and the thyroid cartilages makes it difficult as well; however, the technique may be successful under rigid bronchoscopic guidance and splinting of the airway. Neonates and infants lack a functional cricothyroid membrane. In neonates, it is important to appreciate that the gap between the cricoid and the thyroid cartilage does not allow passage of a 2.0 mm ID ETT. The traditional approach to the difficult pediatric airway has been maintenance of spontaneous ventilation under inhalational anesthesia. Premedication with oral or intravenous atropine (0.01–0.02 mg/kg) is indicated for its vagolytic and antimuscarinic effects. Another important aspect for successful airway management is topicalization of the airway with local anesthesia. In pediatric patients, this may be obtained via nebulization. Airway topicalization can be performed by spraying or swabbing local anesthetic solution or by applying viscous gel to a gloved finger. Also, the “spray-as-you-go” technique can be performed by application of local anesthesia on the vocal cords under direct vision. The maximum dose of local anesthetic allowed should be calculated before topicalization technique. The drug of choice is lidocaine because it has the best safety profile; it has a maximum dose of 5 mg/kg. Agents containing benzocaine, such as Cetacaine spray, Americaine ointment, and Hurricaine ointment, gel, or spray, should be avoided in infants and young children because of the risk of methemoglobinemia.

Extubation of the Difficult Airway Extubation of the infant or child with a DA should be orchestrated as carefully as intubation of the infant or child with a DA. The management of the difficult pediatric airway does not end until successful extubation has been performed. If the safety of extubation is questionable, it may be performed over an airway catheter or guidewire. Extubation may be postponed until an air leak develops, as in the case of epiglottitis or airway edema. If airway edema is suspected, administration of a corticosteroid such as dexamethasone may be beneficial. Postoperative ventilation may be indicated as well until the edema resolves. The infant or child with a DA should only be extubated when personnel capable of reintubating them are available. Extubation itself should be performed in the operating room or in the ICU, where appropriate equipment for reintubating the infant or child is immediately accessible. Generally, if there is doubt or debate as to whether the infant or child with a DA is ready for extubation, then it is usually better to leave them intubated.

Summary Unexpected difficulties with airway management in otherwise healthy children after exclusion of predictors of difficult intubation such as mandibular hypoplasia, limited mouth opening, and facial asymmetry including abnormalities of the ear, syndromes, obstructive sleep apnea, and stridor are very rare. If they occur, they are probably a result of inexperience, inadequate supervision, and lack of pediatric airway training. Thorough pre-operative assessment and anticipation of airway difficulties as well as education, continuous training, and regular practice in basic airway

Suggested Reading Jain RR, Rabb MF . The difficult pediatric airway. In: Hagberg CA, ed. Benumof’s Airway Management. 3rd ed. Philadelphia: Mosby, 2012:723–760.

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management are necessary to reduce the incidence of pediatric airway difficulties. Apart from inexperience with the pediatric airway, a majority of morbidity and mortality in pediatric airway management is attributed to a failure to recognize and overcome functional airway problems because of insufficient depth of anesthesia or inadequate muscle paralysis rather than failure to intubate.

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Chapter 16

Difficult Airway Supplies

William H. Daily, MD

Objectives • Provide suggested supply lists for difficult airway wall-mounted boxes. • Provide suggested supply lists for portable difficult airway mobile carts. • Provide suggested supply lists for portable difficult airway tackle boxes.

Introduction As the variability of difficult airways continues to expand in the operating room, as well as external locations, the practitioner is faced with many challenges. Although the practitioner may be able to handle the majority of these experiences, it is imperative that difficult airway supplies are readily available when needed. With this in mind, a list of suggested supplies for these eventualities is presented in this chapter.

Operating Room Airway Supply Box At the author’s institution, there is an emergency airway box attached to the wall of every operating room. (Fig. 16.1) The opening hinge to the box is secured with a plastic tie to prevent pilfering of supplies. The box has a plexiglass cover to allow easy visualization of the following contents. Individual contents may be changed for your practice patterns.

Adult Emergency Airway Inventory List • • • • • •

Cricothyrotomy kit (6.0 mm) cuffed Bougie (15 Fr) Cook Airway Exchange Catheter (19 Fr) LMA #3, #4 Emergency transtracheal airway catheter Aintree intubation catheter

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Figure 16.1 Wall-mounted emergency airway box containing a cricothyrotomy kit, bougie, 19F Cook AEC, disposable LMA, Aintree intubation catheter, and a transtracheal airway catheter.

Pediatric Emergency Airway Inventory List • • • • • •

Cricothyrotomy kit (4.0 mm) Bougie (10, 15 Fr) Cook airway exchange catheter (8, 11, 19 Fr) LMA #1, #2, #3 Emergency transtracheal airway catheter Aintree intubation catheter

Portable Difficult Airway “Tool Box” A portable “fishing tackle box” is also used at the author’s institution; it has two levels and is easily secured with a plastic tie on the closing hinge (Fig. 16.2). This allows a sealed, well-supplied box to be available without anyone “borrowing” the contents. Contents can be adjusted for individual practice patterns.

Drawer 1 • • • • • • • •

Miller Blade #2, #3 Mac Blade #3, #4 Video laryngoscope Magill forceps Laryngoscope handle × 2 Tongue blade × 4 Oral airways 80 mm, 90 mm, 100 mm × 2 ea. ETT 7.0, 7.5, 8.0 mm with stylets and 10 mL syringes

Drawer 2 • ETT sizes 6.0 mm to 8.5 mm • Intubation stylet

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Figure 16.2 Portable “fishing tackle box” containing emergency airway equipment, including direct laryngoscopes, oral and nasal airways, ETTs of various sizes, LMAs, and drugs (e.g., induction agents, paralytics, and local anesthetics).

• • • • • • • • • • •

Airway exchange catheter (19 Fr) Aintree intubation catheter (19 Fr) Bougie (15 Fr) LMA #3, #4, #5 Exhaled CO2 detector Nasal trumpets size 28, 30 × 2 ea. 20 mL syringes × 4 10 mL syringes × 6 18 G needles × 10 10 mL saline filled syringes × 6 Emergency drug pack from pharmacy (includes water-based lubricant, propofol, etomidate, succinylcholine, rocuronium, Bicitra, and phenylephrine)

Difficult Airway Cart An alternative to a difficult airway box is a mobile cart, which has the advantage of being easily transported to different locations, as needed. If several carts are needed because of the number of locations, then each cart should be set up in an identical fashion. This allows the user to be familiar with the location and operation of the equipment on each cart. These supplies should be customized to meet the specific needs, preferences, and skills of the practitioner and the health-care facility. Suggested set-up is:

Drawer 1 • • • • •

Airways: One each of all sizes (oral and nasal) Laryngoscopes: Miller, Macintosh: (one each of all size blades); video laryngoscope of some type Lidocaine 4% solution (one bottle), lidocaine ointment, lidocaine jelly Atomizer, nebulizer, gloves, 4″ × 4″ gauze pads, 1″ plastic tape, tongue depressors Water-based lubricant, benzoin swabs, anti-fog solution

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• • • • • •

Magill forceps Cricothyrotomy kit Bronchoscope-ETT adapter (Bodai connector) Exhaled CO2 detector Intubation catheter Retrograde intubation kit

Drawer 2 • Endotracheal tubes: Two of each size 2.5 mm to 6.5 mm (uncuffed). Two of each size 3.5 mm to 8.5 mm (cuffed) • Intubating LMA (one set all sizes, 1–5) • LMA UniqueTM, ProsealTM (one set all sizes, 1–5) • ETT stylet: adult and pediatric • 3 mL, 5 mL, and 10 mL syringes and assorted sized needles

Drawer 3 • Oxygen masks (simple and non-rebreather), nasal cannula, oxygen tubing • Face masks • Combitube/Laryngeal Tube (adult and pediatric)

Drawer 4 • ETT exchange catheters • Jet ventilation system • Lightwand

Top of the Cart • Fiberoptic bronchoscope: adult and pediatric, video monitor, light source

Summary Preparation and practice are key elements for dealing with the difficult airway. Utilization of standard, readily available supplies are an invaluable aid whenever the difficult airway presents. Depending on the patient population, the practitioner’s level of expertise, and practice parameters, differences in supplies utilized are expected. The key factor is that a standard set of emergency airway supplies be readily available when the difficult airway presents. The presence of trained assistants (nurses, anesthesia technicians or respiratory technicians, or even another anesthesiologist or surgeon, if necessary) can make the difference in the critical airway case.

Suggested Reading Dunn S, Connelly NR, Robbins L. Resident Training in Advanced Airway Management. J Clin Anesth 2004;16:472–476. American Society of Anesthesiologists Task Force on Management of the Difficult Airway. 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 2003;64(6):13–19. Jain RR, Rabb MF . The difficult pediatric airway. In: Hagberg CA, ed. Benumof’s Airway Management. 3rd ed. Philadelphia: Mosby, 2012:723–760.

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Chapter 17

Special Considerations for Out of the Operating Room and Cardiopulmonary Resuscitation Sam D. Gumbert, MD

Objectives • • • • •

Outline Basic Life Support guidelines and management. List the options for initial airway management during CPR. Evaluate the successful placement and usages of the different airways. Discuss alternative methods of oxygen delivery during CPR. Recognize airway challenges during emergency resuscitation.

Introduction The need for a secured airway does not always occur in the controlled setting of the operating room. Often, emergency scenarios present themselves in less-than-ideal circumstances. In fact, out-of-hospital cardiac arrest is a common problem in the United States, affecting between 235,000 and 325,000 people each year. Recently, the American Heart Association (AHA) has revised its Basic Life Support (BLS) and cardiopulmonary resuscitation (CPR) guidelines to reflect data that recommend good quality chest compressions over initial airway management and breathing. Even so, endotracheal intubation still remains the gold standard for securing the airway during emergency resuscitative procedures. Although there are varying success rates to this practice, there are several methods and alternatives to basic and advanced airway management that can be employed for any given scenario. Proper application of these guidelines and tools may reduce complications and improve outcomes during airway management and CPR outside of the operating room.

Guidelines for Adult Cardiopulmonary Resuscitation Adult Basic Life Support and Cardiopulmonary Resuscitation Guidelines In 2010, the AHA revised the recommended CPR process from the traditional Airway-BreathingCirculation (A-B-C) to Circulation-Airway-Breathing (C-A-B). During low blood flow states such as cardiac arrest, oxygen delivery to the brain and heart is limited primarily by blood flow as

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opposed to arterial oxygen content. It has been shown that in the absence of a hypoxic etiology, the oxygen content of the lungs is enough to maintain a sufficient PaO2 for the few minutes of CPR. Cardiac-only resuscitation and minimizing delays or interruptions in chest compressions have been shown to improve survival. Current evidence does not show any difference in survival rates between chest compressions delivered alone and chest compressions combined with positive pressure ventilation. The AHA now recommends that chest compressions be initiated before rescue breaths or advanced airway placement. Rescue breaths are now provided after the first cycle of chest compressions. The exception to the cardiac-centered BLS approach is in infants and children where cardiorespiratory arrest is usually secondary to hypoxia rather than a primary cardiac event. As a result, initial resuscitation in this patient population is directed toward respiratory support.

Goals of Managing a Collapsed Patient in a Hospital Setting • Recognition of cardiorespiratory arrest or emergency and activation of emergency response team • Early, high-quality CPR • Early defibrillation with an automated external defibrillator (AED) • Early advanced life support followed by post-resuscitation care by health-care professionals

CPR Tip • The updated 2010 AHA CPR guidelines recommend beginning chest compressions before initial airway management (Circulation-Airway-Breathing).

Patient Assessment • Turn the patient onto his/her back and confirm the patient is unconscious. • Check patient’s pulse (