Airway Management Instruction in the Operating Room

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Chapter 53 Airway Management Instruction in the Operating Room

Robert Wong, Robert T. Naruse, Elizabeth C. Behringer

I Introduction

Airway management of either the routine or the difficult airway remains a critical aspect of both anesthesiology training and lifelong anesthetic practice. Anesthesiologists remain the most recognized “airway management specialists” and are routinely involved in elective and emergency procedures involving securing the airway throughout the hospital. Anesthesiologists may be asked to provide a secure airway as an application of advanced cardiac life support during cardiorespiratory arrest, as part of an elective or emergency surgical or radiologic procedure, or in the intensive care unit (ICU).

The American Society of Anesthesiologists (ASA) closed-claims analyses are a series of publications that review closed malpractice claims against anesthesiologists gleaned from the databases of 35 medical liability insurance carriers. The initial 1990 report reviewed adverse respiratory events associated with anesthesia care during the 1970s and 1980s.¹ In the 1970s, 55% of all claims of death or brain damage were caused by anesthetic-associated adverse respiratory events. Respiratory events during anesthetic care leading to adverse outcomes were the largest group of injuries resulting in malpractice litigation. This landmark study highlighted the three mechanisms associated with adverse outcomes: inadequate ventilation, unrecognized esophageal intubation, and difficult endotracheal intubation. Other events noted in a subsequent study included airway trauma, pneumothorax, aspiration of orogastric contents, and bronchospasm. These less common adverse respiratory events can be associated with anesthetic care as well.²

In 1998, a follow-up study noted a significant change in airway-related closed claims during the 1990s.³ During this decade, a 10% decrease in the incidence of anesthetic-related adverse respiratory events was noted. This dramatic decline can be attributed to the routine use of pulse oximetry, use of capnography, and the advent and widespread use of the ASA Difficult Airway Algorithm in continuing education.^4,⁵ Additional factors that play vital roles include residency training specifically focused on airway management, continuing education in airway management, and scientific literature on management of the difficult airway.⁶

II Importance of Lifelong Learning in Airway Management

The importance of clinical education in airway management during residency training and in the postgraduate setting can be underscored by a brief review of airway management in the ICU. Anesthesiologists are often consulted for airway management in the ICU during both residency training and postgraduate practice.⁷ Nayyar and Lisbon⁸ surveyed anesthesiology residency training programs with regard to emergency airway management practices outside the operating room (OR). In the vast majority of programs surveyed, anesthesiologists performed most of the intubations on the hospital ward, including the ICU. This study supports the importance of tailoring airway practice to the patient environment, as supported by the scientific literature.

Mort ⁹ reviewed the incidence of hemodynamic and airway complications associated with tracheal reintubation after unplanned extubation in the ICU. The 57 patients reintubated after self-extubation were examined over a 27-month period; 93% of reintubations occurred within 2 hours of self-extubation. Of these patients, 72% had hemodynamic compromise or airway-related complications such as hypotension (35%), tachycardia (30%), hypertension (14%), multiple laryngoscopic attempts (22%), difficult laryngoscopy (16%), difficult intubation (14%), hypoxemia (14%), and esophageal intubation (14%). One patient required a surgical airway. One case of “cannot ventilate, cannot intubate” leading to cardiac arrest and death occurred. Less than one third of the patients studied had a “mishap-free” reintubation in the ICU.⁹ Thus, it was recommended that individual ICUs develop strategies to decrease the rate of self-extubation based on patient safety and the impact of emergency airway management.

Mort ^10,¹¹ reported two additional studies of airway management in remote settings pertinent to clinical practice. The first study used an emergency intubation database from 1990 to 2002 in support of the ASA guidelines for difficult airway management, concluding that when conventional intubation techniques fail after three attempts, advanced airway devices should be used and immediately available.¹⁰ The database was divided into two periods. Period A (1990-1995) included 340 intubations in which accessory airway devices, such as the laryngeal mask airway (LMA), bougie, Combitube, or fiberoptic bronchoscope, were not routinely available. Period B (1995-2002) included 437 patients for whom these devices were readily available. The relationship between the use of any accessory airway devices and airway and hemodynamic complications, including number of intubation attempts, hypoxemia, regurgitation, aspiration, bradycardia, and dysrhythmia, was determined. Intubations were performed in the surgical ICU, medical ICU, hospital ward, neurosurgical or trauma ICU, coronary care ICU, emergency department, and postanesthetic care unit. The study found a 33% reduction in hypoxemic episodes (oxygen saturation [SpO₂] <90%) and a 50% reduction in severe hypoxemic episodes (SpO₂ <70%) in group B patients, for whom accessory airway devices were readily available. Regurgitation was reduced from 4% to 1.7%, aspiration from 2.1% to 0.2%, bradycardia from 5% to 2%, dysrhythmia from 9.1% to 3.7%, and multiple intubation attempts from 30% to 15% in group A and B patients, respectively. The use of accessory airway devices increased from 5% in Group A patients to 42% in Group B patients. Notably, LMA use increased 21-fold. The aggressive approach of incorporating the ASA difficult airway management guidelines by early intervention with accessory airway devices led to a remarkable reduction in multiple attempts at laryngoscopy and a decreased incidence of airway and hemodynamic complications. This study confirms the importance of application of the ASA algorithm outside the OR setting and also justifies the immediate availability of a well-stocked difficult airway cart in all hospital locations where emergency airway management is performed, especially the ICU setting. It also illustrates the importance of familiarity with and experience in the use of accessory airway devices as a mandatory part of the standard of care in routine anesthetic practice.

In the second study, Mort ¹¹ reviewed the utility of exchanging an endotracheal tube (ETT) in the ICU by two methods: direct laryngoscopy (DL) or airway exchange catheters (AECs). ETT exchanges from an 8-year quality improvement database were reviewed. Patients with an uncompromised glottic view (Cormack-Lehane views 1 and 2) were divided by method of exchange: DL (n = 99) versus AEC, Cook 14 or 19 French (n = 34). Hypoxemia, intubation attempts, esophageal intubation, bradycardia, cardiac arrest, and the need for a surgical airway were compared. Successful ETT exchange on the first attempt was higher with use of an AEC (95% AEC vs. 62% DL). The need for multiple attempts at laryngoscopy was higher in the DL group (26% DL vs. 2.9% AEC). In addition, rescue airway techniques were used more frequently in the DL group (16 of 99 cases; a surgical airway was necessary in 5 of the 16 DL-rescued airways). No rescue maneuvers were necessary in the AEC group. Hypoxemia and severe hypoxemia, esophageal intubation, bradyarrhythmias, and cardiac arrest during DL for ETT exchange were also more frequent in the DL group. It was determined that use of an AEC during ETT exchange in the ICU lowered the risk of complications considerably, even in the presence of a previously uncompromised view of the glottic inlet. This study also highlights the importance of familiarity with alternative techniques to DL as part of safe airway management and anesthetic practice.

Mort ¹² also studied the hazards of repeated attempts at laryngoscopy in critically ill patients, with 2833 critically ill patients entered in an emergency intubation quality improvement database. Patients had cardiovascular, pulmonary, metabolic, neurologic, or traumatic injuries. In this retrospective review, the practice analysis documented in the database was evaluated for both airway and hemodynamic complications. These variables were correlated with the number of laryngoscopic attempts required for successful intubation. All the patients required emergency intubation outside the OR setting. A statistically significant increase was seen in airway-related complications when the number of laryngoscopic attempts increased to two or more intubation attempts. The incidences of hypoxemia, regurgitation of gastric contents, aspiration of gastric contents, bradycardia, and cardiac arrest were significantly higher when the number of attempts at conventional laryngoscopy increased. This study supports the recommendation of the ASA Task Force on Management of the Difficult Airway guidelines to limit the number of laryngoscopy attempts and to be facile and familiar with alternative techniques of difficult airway management.¹²

These studies highlight the importance of committed, lifelong learning in the variety of techniques in advanced airway management available to the anesthesiologist. This chapter focuses on the means available to accomplish this goal by review of pertinent supporting literature.

III Teaching Airway Management—the Components

The topic of teaching airway management skills can be divided into several components, including anatomy, evaluation of the airway, and teaching materials, such as airway simulators (see Chapter 52). In addition, the scientific literature supports teaching techniques in mask airway management, direct laryngoscopy, fiberoptic intubation, supraglottic airway ventilation or assisted intubation, video laryngoscopy, and surgical airway management. The scientific literature also highlights the utility of instruction in airway management during anesthesiology residency training and postgraduate courses.

Several authors advocate review of basic anatomy as essential groundwork for mastery of difficult airway management. Gaiser ⁶ published a review of teaching airway management skills, advocating use of an anatomy textbook as a valuable teaching tool. Review of basic airway anatomy can be achieved in lecture format or self-study.^6,^13,¹⁴ Katz and colleagues¹⁵ used videotapes to review basic airway anatomy as a part of their learning module in fiberoptic intubation (FOI). Haponik and associates¹⁶ used a computer software program to teach tracheobronchial anatomy as a preparation for a virtual training course on FOI. Evaluation of the airway for potential difficulty is an integral part of difficult airway management. The second iteration of the ASA practice guidelines stresses the importance of a thorough history and physical examination of each patient for anticipated difficulty.⁵ This evidence-based guideline incorporates 11 physical examination points related to the airway that provide a succinct set of predictors of potential airway difficulty (see Chapter 10). The current guidelines for management of the difficult airway may also be found at the ASA website, www.asahq.org.

Although practicing anesthesiologists and anesthesiology residents have unlimited access to techniques for evaluation of potential difficulty in airway management, other physicians do not. The American College of Obstetricians and Gynecologists (ACOG) emphasizes the importance of identifying parturients at risk for possible difficult intubation (DI) during emergency delivery: “The obstetric care team should be alert to the presence of risk factors that place the parturient at risk for complications from general anesthesia.”¹⁷ At the Hospital of the University of Pennsylvania, Gaiser and associates¹⁸ studied the ability of obstetricians to recognize parturients at risk for DI in light of the ACOG policy statement. The 160 parturients had an airway examination conducted by four separate physicians, an attending and resident obstetrician, as well as an attending and resident anesthesiologist. The physicians were asked to complete a questionnaire about DI, use of antepartum consultation, and the choice of labor analgesia after each patient’s examination. During the first 80 airway examinations, the obstetricians did not receive any guidance or education on recognition of the difficult airway and complications associated with it. For the following 80 airway examinations, the obstetricians received a 30-minute tutorial on methods to examine the airway for potential difficulty, as well as the complications of DI. The anesthesiologists’ responses were used as the standard. The sensitivity, specificity, and positive and negative predictive values were calculated for the responses of the other physicians. Unfortunately, brief, 30-minute tutorials did not affect the results of the obstetricians’ ability to assess the airway. Instruction did not affect the number of consultations requested by either resident or attending obstetricians for possible DI. However, attending obstetricians were significantly more likely to utilize epidural analgesia for 2 cm of cervical dilation in women with a possible difficult airway.¹⁸ This study highlights the importance of discussing airway management and its potential complications with surgical colleagues because it can affect clinical judgment, in this case, a change in the choice and timing of labor analgesia in parturients with a suspected difficult airway.

IV Instruction in Specific Techniques OR Devices

The scientific literature is replete with studies pertaining to mastery of specific devices and techniques of airway management, and a brief review of supraglottic airways, fiberoptic intubation, and the surgical airway is warranted.

A Laryngeal Mask Airway

The past 30 years has seen a proliferation of supraglottic airway devices. Starting with the laryngeal mask airway described in 1983 by Brain,¹⁹ 14 different supraglottic devices were listed by Cook²⁰ in 2003. Recommended training for the use of these devices varies according to idiosyncrasies of the individual device. The LMA remains the prototypical supraglottic airway.

Brimacombe ²¹ provides an excellent review of educational considerations with the LMA, summarizing the myriad sources detailing skills acquisition using the various versions of the LMA. Gurman and coauthors²² compared retention of airway management skills in 47 medical students instructed in the use of direct laryngoscopy, LMA, and Combitube placement during a 2-week rotation in anesthesiology. Mannequins were used for teaching and testing. The authors noted no diminution in skill with any device over a 6-month period following training.

Dickinson and Curry ²³ studied the efficacy of mannequin training for proper LMA insertion in paramedics attending an Advanced Cardiac Life Support (ACLS) training course.²³ A high success rate in the use of the LMA led to the conclusion that this was a suitable alternative to live training in patients. Ferson and coworkers²⁴ studied 20 anesthesiologists over 2 months, examining the efficacy of instruction in the use of the LMA by comparing manual or videotape training with hands-on training by an experienced anesthesiologist using a mannequin. More than 90% of participants in the hands-on training group achieved passing scores for LMA insertion technique after 17 insertions. Less than 30% of the group using manual videotape training achieved this score.

Brimacombe ²¹ suggests that four phases of education are required to incorporate the LMA into clinical practice (Box 53-1). Phases 2 to 4 are enhanced when a mentor (e.g., experienced LMA user) is available to the novice for individualized training. Coulson and coauthors²⁵ showed that digital insertion of the ProSeal LMA (pLMA) using inexperienced personnel after mannequin-only training was as successful as in anesthetized adults. Success rates of approximately 90% after 2 minutes were found in each group.

Box 53-1 Phases of Education for Incorporation of Laryngeal Mask Airway (LMA) into Clinical Practice

Phase 1: Reading and viewing instructional material to gain an understanding of basic concepts on LMA use.

Phase 2: Mannequin or cadaver training to develop basic motor skills for LMA use.

Phase 3: Use of LMA clinically in simple, elective cases to acquire basic clinical skills.

Phase 4: Use of LMA in more complex cases to acquire advanced clinical skills.

The I-gel (Intersurgical, Workingham, UK) is another supraglottic airway device (SAD) with demonstrated promise. Wharton and associates ²⁶ demonstrated an 82.5% success rate in mannequins and 80% success rate in anesthetized patients on the first attempt by novice users (medical students, non-anesthesia physicians, allied health professionals). Roberts²⁷ concluded that mannequin-only training in the emergency technique for LMA insertion is as effective as live patient training. However, Rai and Popat²⁸ note the limitations of mannequin-only studies and training, emphasizing that even advanced, high-fidelity simulation mannequins are unable to recreate the “feel” and finer aspects of human airway anatomy.

B Fiberoptic Intubation

In an early study of clinical competence in the performance of fiberoptic laryngoscopy and endotracheal intubation, Johnson and Roberts ²⁹ hypothesized that an acceptable level of technical expertise in fiberoptic intubation could be acquired within 10 intubations while maintaining patient safety. The learning objectives included an intubation time of 2 minutes or less and greater than 90% success on the first intubation attempt. Ninety-one ASA class I or II patients with normal laryngeal anatomy undergoing general anesthesia were intubated orally with an Olympus LF-1 fiberoptic scope after induction of general anesthesia. The mean time for intubation was 1.92 (±1.45) minutes. Four anesthesiology residents without prior fiberoptic experience intubated at least 15 patients each. A learning curve was generated using logarithmic analysis of the mean (±SD) time for intubation of patients 1 to 15 for all residents combined. The learning curve noted that the mean intubation time decreased from 4.00 (±2.91) minutes to 1.52 (±0.76) minutes within the first 10 intubations. After the tenth asleep FOI, the mean intubation time was 1.53 minutes, with greater than 95% success rate for the first attempt. No clinically significant changes in oxygen saturation (SO₂), mean arterial pressure, or heart rate were noted during asleep FOI in this study. An acceptable level of technical expertise in FOI can be achieved safely by performing at least 10 elective asleep FOIs by novice anesthesiologists.²⁹

Erb ³⁰ evaluated teaching orotracheal FOI in 100 anesthetized, spontaneously breathing patients. Five anesthesia residents without prior experience in FOI participated in this study. Each resident randomly intubated 10 spontaneously breathing patients (group A) and 10 paralyzed patients (group B) tracheally. An overall success rate of 96% was defined as successful endotracheal intubation in two attempts or less. No difference was found between the two groups. During FOI, SO₂ remained over 95% in group A, whereas 2 of 10 patients in group B had SO₂ fall below 95% during fiberoptic attempts. The authors noted that FOI under conditions of spontaneous respiration is a well-established, standard-of-care technique of difficult airway management. This study demonstrated a feasible and safe method to train novices in the skill of FOI under conditions of general anesthesia and spontaneous ventilation.³⁰

At the Children’s Memorial Hospital at Northwestern University, Wheeler and colleagues ³¹ performed a study teaching residents pediatric FOI. Twenty clinical anesthesia second-year (CA-2) residents were randomly assigned to the traditional teaching group (FOI with standard eyepiece) or the video-assisted group (FOI using integrated camera and video screen). All residents were novices in pediatric FOI. One of two attending anesthesiologists supervised each resident during the elective FOI of 15 healthy children ages 1 to 6 years. Variables included time from mask removal to confirmation of successful endotracheal intubation by end-tidal carbon dioxide detection and FOI attempts up to 3 minutes or three attempts. The primary outcome of time to success or failure was compared between the two groups. Failure rates, as well as the number of attempts, were also compared. Of 300 intubations attempted; eight failed. On average, the group using video-assisted FOI as a training tool was faster and three times more likely to achieve successful FOI. The video-assisted group also had significantly fewer attempts at intubation than the residents in the traditional group. The authors concluded that a video-assisted system, where the attending anesthesiologist is able to provide real-time feedback during FOI of pediatric patients, was superior as a teaching method to the traditional teaching model.³¹ The newer generations of video FOI equipment are especially useful in such teaching situations. This type of equipment allows for viewing by multiple persons, as well as capture of still images and videos for later review (Olympus MAF-Type GM, TM, LF-V).

Ovassapian ³² provides a succinct review of learning fiberoptic intubation techniques, emphasizing the following points to encourage more frequent use of the fiberscope in anesthesia and critical care practice⁸ (Boxes 53-2 and 53-3:

1. The techniques of FOI are not difficult to learn. Mastery of the art of fiberoptic airway management readily develops with time and experience.

2. The technique of FOI is different from rigid laryngoscopy. Without formal training, the anesthesiologist should not expect immediate and successful use of the fiberscope for endotracheal intubation.

3. No anesthesiologist should perform a new technical task without studying and developing the required base of knowledge involved in its performance.

4. The fiberscope is a simple but sophisticated airway management tool. It should be utilized to its full diagnostic and therapeutic potential in airway management. The greater the experience of the anesthesiologist in using the fiberscope under a variety of clinical circumstances, the greater is the degree of skill that develops with time.

5. The essential steps for successful use of the fiberscope include organizing and maintaining a functional fiberoptic cart, setting up an instrument and intubation checklist, and practicing on models to develop the skills necessary for fiberoptic maneuvering.

Box 53-2 Guidelines for Successful Fiberoptic Intubation

1. Organize a functional fiberoptic cart.

2. Maintain a functional fiberscope.

3. Follow a checklist prior to each use.

4. Skillfully manipulate the fiberscope.

5. Follow approaches and steps of fiberoptic intubation.

Naik and coauthors ³³ attempted to determine if FOI skills learned outside the OR on a simple model could be transferred to the clinical setting. Twenty-four first-year anesthesiology and second-year internal medicine residents were recruited for this study. Residents were randomly allocated to a didactic teaching group (n = 12) or a model-training group (n = 12). The didactic teaching group received a detailed lecture from an expert in FOI. The model-training group was expertly guided through the tasks performed on a simple model designed to refine fiberoptic manipulation skills. After the training session, residents performed a fiberoptic orotracheal intubation on healthy, consenting, anesthetized, paralyzed female patients who were undergoing elective surgery. Patients were predicted to be easy laryngoscopic intubations. Two “blinded” anesthesiologists evaluated each patient. The authors found that the model-training group outperformed the didactic group in the OR when evaluated with a global rating scale, as well as a preparatory checklist. The model-trained residents completed fiberoptic orotracheal intubation significantly faster and more often than didactic-trained residents. The authors concluded that training fiberoptic orotracheal intubation skills using a simple model is more effective than conventional didactic instruction, when incorporating skills in the clinical setting. They suggested that incorporation of model-based training in FOI may greatly reduce the time accompanying subsequent training in the OR.³³

In a study of an educational resource specific to the acquisition and maintenance of endoscopic skills, Marsland and colleagues ³⁴ describe the use of DEXTER. This nonanatomic, endoscopic dexterity–training system is designed to encourage practice in fiberoptic endoscopy as well as establish and maintain a state of procedural readiness. Educational training systems such as DEXTER help to maintain these skills even if the anesthesiologist’s clinical exposure to difficult airway management is sporadic.

The pulmonary literature also addresses the issue of training in fiberoptic bronchoscopy. In a study of “virtual reality” bronchoscopic training, Colt and colleagues ¹³ hypothesized that novice trainees in the procedure of flexible fiberoptic bronchoscopy could rapidly acquire basic skills using a virtual-reality skill center. Furthermore, these trainees would compare favorably with senior colleagues who had been conventionally trained on live patients. Five novice bronchoscopists entering a pulmonary–critical care training program were studied prospectively. Flexible fiberoptic bronchoscopic inspection of the tracheobronchial tree was taught using a virtual-reality bronchoscopic skill center, including a proxy flexible bronchoscope, robotic interface device, and personal computer with monitor and simulation software (PreOp Endoscopy Simulator; Immersion Medical, Gaithersburg, Md). The proxy bronchoscope, modeled after a conventional fiberoptic bronchoscope, provides realistic images to the users as they navigate through virtual tracheobronchial anatomy.¹³ The authors measured dexterity, speed, and accuracy using the skill center as well as an inanimate airway model before and after 4 hours of group instruction and 4 hours of individual unsupervised practice. The results of this group were compared with those of a control group of four skilled physicians. Each of these pulmonologists had performed at least 200 bronchoscopies during 2 years of training. They found that novice bronchoscopists significantly improved dexterity and accuracy using either the virtual or inanimate airway model. After training, fewer bronchial segments were missed, and fewer contacts with the tracheobronchial wall occurred. Speed and total time spent with unvisualized bronchial anatomy did not change. After training, novice performance equaled or surpassed that of skilled physicians. Novices tended to perform more thorough examinations of the tracheobronchial tree. They missed significantly fewer bronchial segments in both the inanimate and virtual simulation models. The authors concluded that a short, focused course of instruction and unsupervised practice using a virtual bronchoscopy simulator enabled novices to achieve a level of technical skill similar to that of colleagues with several years of experience.¹³ These skills were reproduced in an inanimate airway training model that mimics direct care of patients.

Conversely, Crabtree and associates ³⁵ showed that simulator performance may not be a good indicator of FOI performance in the clinical setting. Chandra and colleagues³⁶ concluded that there was no added benefit from training on costly virtual-reality models compared with low-fidelity, nonanatomic models designed to refine FOI skills with respect to transfer of skills to actual patient care.

C Surgical Airway

Lack of experience is the main source of procedural failure with cricothyrotomy, although hands-on training is also lacking. A study evaluating difficult airway instruction found that although 80% of American anesthesiology residency training programs taught cricothyrotomy, 60% of these courses consisted of only lectures.³⁷ As a result, many physicians lack the necessary skills to perform a cricothyrotomy correctly or expeditiously.

Correct and safe performance of cricothyrotomy is life-saving in patients who cannot be ventilated or intubated successfully. Eisenburger and coworkers ³⁸ compared conventional surgical technique (group 1) versus Seldinger technique (group 2) emergency cricothyrotomy performed by inexperienced clinicians in adult human cadavers. The ease of use and times to locate the cricothyroid membrane, to tracheal puncture, and to first lung ventilation were compared. Participants were allowed a single attempt at the procedure. A pathologist dissected the neck of each cadaver to assess the correct position of the tube and any injury to the airway. Subjective assessment of the technique on a visual analog scale (1 = easiest to 5 = most difficult) was conducted. The age, height, and weight of the cadavers used in this study were uniform. Subjective assessment of each method as well as anatomy of the cadavers was not statistically different between the two groups. Correct tracheal placement of the tube was achieved in 70% of surgical cricothyrotomies (n = 14) and 60% of Seldinger cricothyrotomy (n = 12). Five attempts in group 2 (Seldinger) were aborted because of kinking of the guidewire. Time intervals between start of the procedure and location of the cricothyroid membrane, tracheal puncture, and first ventilation were not statistically different. Thus, in this limited study, each method showed equally poor performance and suggested that further study be undertaken to define the learning curve of this life-saving procedure.³⁸

McCarthy and colleagues ³⁹ attempted to define the accuracy of cricothyrotomy performed in canine versus human cadaver models during surgical skills training. Thirty-three advanced trauma life support (ATLS) physician students performed cricothyrotomy in canine models. Ten flight nurses performed a bimonthly surgical skills practicum on similarly prepared animals. Neck specimens of the euthanized animals were excised, fixed, and mapped by the authors. Subsequent courses in ATLS used human cadavers and similarly prepared trainees. In these models, cricothyrotomy sites were mapped in situ. In canine models, 47 neck specimens of 52 attempted cricothyrotomies were inspected and mapped. Four specimens were excluded from the final analysis because of multiple attempts at cricothyrotomy. Thirteen of the 43 analyzed canine models had a misplaced cricothyrotomy (30.2%). Cricothyrotomy attempts were correct 27 of 28 times in the human cadaver model (96.4%). The authors concluded that placement accuracy in the canine model was low, and that human cadaver models were superior for realistic training.³⁹

Wong and associates ⁴⁰ attempted to determine the minimum training experience required to perform surgical cricothyroidotomy in 40 seconds or less in mannequins. The 102 anesthesiologists participating in this study were shown a video demonstrating the Seldinger technique of cricothyrotomy. They then performed 10 consecutive cricothyrotomy procedures on a mannequin using a preassembled percutaneous dilatational cricothyrotomy set (Melker Emergency Percutaneous Dilatational Set; Cook Critical Care, Bloomington, Ind). Each attempted procedure was timed from initial palpation of the skin to successful lung insufflation. Cricothyrotomy was considered successful if performed in 40 seconds or less. Cricothyrotomy time was considered to have reached a plateau when there was no significant reduction in time in three consecutive attempts. A significant reduction in time for successful cricothyrotomy was found over the 10 attempts. The cricothyrotomy time reached a plateau by the fourth attempt. Success rate reached a plateau by the fifth attempt. The authors concluded that mannequin practice for percutaneous dilational cricothyrotomy led to a reduction in cricothyrotomy time and improved success rates of this procedure. By the fifth attempt, 96% of participants were able to perform a cricothyrotomy successfully in 40 seconds or less. The authors recommended that clinicians providing emergency airway management should be trained on mannequins for at least five attempts or until performance times of 40 seconds or less are achieved. Clinical correlation and optimal retraining intervals for this procedure have yet to be determined.⁴⁰

Friedman and colleagues ³⁷ compared cricothyrotomy skills acquired in a simple inexpensive model to those learned on a high-fidelity simulator using valid evaluation instruments and testing on cadavers. First-year and second-year anesthesia residents were recruited. All performed a pretest videotaped cricothyrotomy on cadavers. Subjects were then randomized into two groups. The high-fidelity group (n = 11) performed two cricothyrotomies on a full-scale simulator with anatomically accurate larynx. The low-fidelity group (n = 11) performed two cricothyrotomies on a low-fidelity model constructed from corrugated tubing. Within 2 weeks, all subjects performed a post-test. Two blinded examiners graded and timed the performances using a checklist and global rating scale. The results showed no significant difference between the two groups. The authors concluded that skills acquired using the simple model were not significantly different from those acquired using the expensive simulator.³⁷ Skills acquired from both models transferred effectively to cadaver performance.

V Resident Training in Advanced Airway Management

Anesthesiologists are physicians specialized in advanced airway management, including ventilation and endotracheal intubation. Despite extensive exposure to advanced airway management, challenges to intubation and ventilation may be encountered in daily practice. It is vital to provide trainees experience in the recognition and management of the difficult airway. Formal, organized rotations in advanced airway management better prepare future physicians in management of a difficult airway. Training programs with a comprehensive difficult airway rotation are associated with decreased respiratory morbidity and less need for emergency surgical airways.⁴¹

Since the introduction of the ASA Practice Guidelines for Management of the Difficult Airway in 1993, surveys have assessed if training programs are incorporating a difficult airway module in their core curriculum. A recent survey, conducted by a Society of Airway Management (SAM) task force, showed that 43 of 88 ACGME- and ACUDA-approved residency programs offered a formal airway rotation, a significant increase from 33% of residency training programs in 2003.^42,⁴³

Despite an improved emphasis on teaching trainees the recognition and management of the difficult airway, there remains a lack of uniformity with regard to minimum requirements for competencies with a variety of airway devices or techniques. As a result, a trainee’s experience in advanced airway management may vary dramatically from one training program to another. The following reviews discuss factors that are important considerations in the development of a useful and successful difficult airway management curriculum.

In 1995, a survey on formal training in advanced airway management techniques was sent to the program directors of 169 anesthesiology residency training programs in the United States; 143 directors responded.⁴⁴ Formal rotations in advanced airway management were brief and often limited to didactic lectures. Only 27% of responding programs had a formal advanced airway management course in their curriculum, and 60% of these courses were less than 2 weeks in duration.

Subsequently, a number of academic anesthesiology departments published their specific rotations in advanced airway management. Cooper and Benumof ⁴⁵ described the University of California–San Diego Department of Anesthesiology’s advanced airway rotation. The goal of this rotation was to create nonurgent, nonstressful learning situations where a number of airway management techniques can be mastered in patients. The rotation includes the administrative responsibilities of starting an airway rotation. Administrative aspects include (1) approval of the residency program director, the departmental education committee, or both; (2) selecting experienced faculty to serve as instructors; (3) careful scheduling; (4) formulating the didactic program; and (5) having the appropriate equipment available (e.g., a dedicated difficult airway cart). Residents receive a syllabus containing classic and current articles on both airway management devices and techniques before the rotation. The syllabus is the foundation for both formal didactic teaching and informal teaching in the OR.⁴⁵ Before use in any patient, any new or unfamiliar airway device or technique is discussed thoroughly with regard to theory, description, insertion technique, and current clinical practice. Subsequently, the individual device is used in models, mannequins, or both. When invasive techniques are introduced (e.g., retrograde intubation, transtracheal jet ventilation, or percutaneous cricothyrotomy), a special workshop is held at the anatomy laboratory of the medical school. Human cadavers serve as models for instruction in the necessary technical skills involved in the procedure.

Patient selection is critical during this rotation. According to the authors, straightforward patients are ideal, including ASA class I or II patients undergoing elective general anesthesia without the need for extensive monitoring or setup. These patients undergo surgery in the supine position, with ready access to the airway throughout the procedure. Patients with head or neck injury, in whom there is competition for the airway, are generally avoided unless the patient requires an awake intubation technique. Patients with a known or suspected difficult airway are prioritized to the resident on the airway management rotation. A goal of this rotation is to perform advanced airway management techniques for 40 to 50 patients during the 1-month rotation.⁴⁵ Didactic teaching includes performance of a thorough evaluation of the airway based on the current ASA recommendations on difficult airway management.⁵ The findings of every airway examination are discussed with the supervising faculty. Residents are instructed in proper preparation of the patient for awake intubation techniques. In addition, they garner experience in devices such as the LMA, Combitube, lighted stylets, and advanced rigid fiberoptic laryngoscopes. The adjunct use of the fiberoptic bronchoscope (FOB) is encouraged. Once a patent airway is established, the resident is encouraged to identify all pertinent tracheobronchial anatomy by inserting an FOB through a bronchoscope adapter.⁴⁵

Dunn and colleagues ⁴⁶ at Baystate Medical Center in Springfield, Massachusetts, described their resident training in advanced airway management. They developed a formal advanced airway management program consisting of two separate 1-month rotations. Each rotation has a separate focus. One month occurs during the later half of the CA-1 year. The second month occurs during the CA-2 year. Residents are given a set of objectives, a required reading list, and a required number of procedures unique to advanced airway management. These procedures must be performed during the course of the rotation. This rotation consists of a core faculty group with expertise in airway management. According to the authors, five issues must be addressed in order to implement an airway rotation: (1) equipment, (2) core faculty, (3) curriculum, (4) time commitment, and (5) faculty development.⁴⁶

The Baystate Medical Center rotation uses seven difficult airway (DA) carts distributed in five anesthetizing locations. The carts are uniformly set up and stocked. The authors believe that uniformity of equipment enhances physician performance of emergent airway management. Each cart and its contents cost approximately $30,000.⁴⁶ Contents of the DA carts include a variety of face masks, different sizes of the LMA, Combitube, and transtracheal puncture equipment. Each DA cart is equipped with the three modalities of difficult airway management thought to be the most helpful: flexible FOB, intubating LMA (Fastrach; LMA North America, San Diego), and a variety of rigid fiberoptic laryngoscopes. Each cart incorporates a video system, which improves teaching and is an integral part of the program.

Core faculty members are proficient in all modalities of airway management. The size of the core faculty group is sufficient to ensure coverage during vacations, other clinical commitments, and so forth. At least one faculty member is available each day of the rotation. Contact with a core group of faculty ensures that residents master each technique in an adequately supervised fashion.⁴⁶

The curriculum for this rotation includes a required reading list. Each of these publications requires discussion with a core faculty member to demonstrate adequate knowledge of the contents. The first month’s rotation for CA-1 residents focuses on the ASA airway management algorithm, as well as techniques of FOB. The second month’s rotation for CA-2 residents has a separate reading list and focuses on alternative techniques of advanced airway management as well as complications.⁴⁶ Requirements for successful completion of the first month of the rotation include no fewer than 10 fiberoptic intubations, 10 Bullard Scope intubations, and six LMA Fastrach intubations. In the second month of the airway rotation, the resident is required to perform at least 10 additional fiberoptic intubations (at least two pediatric fiberoptic intubations), 10 Bullard intubations, and six LMA Fastrach intubations. Residents in both months of the rotation are encouraged to seek out “known difficult airway” cases on the elective schedule, as well as participate in the preoperative consultation of these patients. A worksheet detailing each difficult airway case is kept by the resident and “signed off” by the core faculty. The authors detail the importance of departmental commitment to advanced airway management training, as well as the development of faculty interested in advanced airway management.⁴⁶

Hagberg and colleagues ⁴³ at the University of Texas Medical School at Houston reviewed the instruction of airway management skills during anesthesiology residency training. This study, a follow-up to Koppel and Reed’s study,⁴⁴ was conducted 3 years after the mandate of the Accreditation Council for Graduate Medical Education (ACGME) requiring that residents have significant experience in specialized techniques of airway management, such as fiberoptic intubation, double-lumen tube placement, and LMA use.⁴³ A survey of all directors of anesthesiology residency programs listed in the Graduate Medical Education Directory for the years 1998 and 1999 was conducted. The survey was sent by both e-mail and fax to each program director. A second copy was sent to non-responders 4 weeks after the initial mailing. Of the 132 program directors surveyed, 79 (60%) replied. Of the 79 respondents, 26 reported programs (33%) that had a difficult airway rotation. Interestingly, this number had increased only slightly since prior publications and the ACGME mandate.⁴³ An advanced airway management rotation was offered throughout the clinical base years of training in 13 (49%) programs of respondents. The rotation was 1 week in duration in 16 (61%) of the cases offering a program. Formal instruction was given before the start of the rotation in 18 (69%) programs. Instruction usually occurred using surgical patients (in 22 or 85% of programs), using ASA I or II patients (in 20 or 77% of programs), and was conducted by select faculty (in 20 or 78% of programs).

The most frequently taught airway management modalities included the flexible FOB and the LMA. Invasive techniques such as percutaneous cricothyrotomy or tracheostomy were taught infrequently. There was a time limitation of 2 to 5 minutes or a maximum number of attempts in device-specific airway management in five programs (19%). A required case number for each device was found in five of the programs surveyed (19%). In this survey, instruction in advanced techniques of airway management occurred most often in the form of video, written instruction, and practice on actual patients undergoing surgical procedures. Nontraditional methods of instruction, such as computer-assisted instruction or patient simulators, were used infrequently. Residents received both skills and written evaluation in 63% of the programs with a specific rotation in advanced airway management.⁴³

This study raised several questions about the instruction of advanced airway management, suggesting further study on the efficacy of different training techniques. The authors are proponents of a future clinical certification process for training in advanced airway management for all anesthesiologists. They suggest that the residency review committees for anesthesiology and the ACGME should establish number requirements for specific airway-related procedures to ensure standardization of resident training. Follow-up studies are warranted when such mandates are established, because standardization of training in these techniques may further decrease airway-related morbidity and mortality.⁴³

Allen and Murray ⁴⁷ addressed the issue of patient consent when teaching airway management skills, suggesting that any procedure that deviates significantly from the standard of care should invoke patient consent. In the authors’ practice, substitution of laryngoscope blades or use of the LMA or lightwand does not require specific patient consent. However, use of the Combitube, FOI, any retrograde technique, or elective repeated instrumentation with several different devices requires patient consent. Most important, the authors stress that constant supervision of residents by experienced faculty is of paramount importance to minimize patient risk. Initial experience in advanced airway management in a simulated environment may further reduce patient risk.⁴⁷

Benumof and Cooper’s reply ⁴⁸ to Allen and Murray⁴⁷ stated that special consent was not necessary for well-established and accepted airway management techniques, especially in the presence of experienced faculty. Constant supervision by experienced faculty ensures against undue force or rough handling of the airway and offers the ability to abort or change an initial airway management technique as needed. In Benumof and Cooper’s published experience of approximately 1000 faculty–airway rotation resident cases, only three adverse outcomes occurred. In two cases, intubation through the self-sealing FOB adapter on an intubating anesthesia mask resulted in a piece of the blue diaphragm being inadvertently carried into the trachea; thus, these adapters were no longer used. In each case, the complication was recognized immediately by the supervising faculty. Bronchoscopy forceps were used in both cases through the FOB’s working channel to retrieve the piece of plastic, without incident. The third event occurred when an improperly sterilized LMA was used. The LMA was inadvertently cleaned in Cidex, and perilaryngeal edema ensued in the patient. The patient was tracheally intubated and experienced no long-term morbidity. The cleaning impropriety was corrected. The authors stress that careful use of accepted methods under strict and expert supervision does not mandate patient consent.⁴⁸

Learning in the OR or emergency room environment is not ideal, because it imposes stressors on both the patient and the student. Possible dental trauma, aspiration, and bruised or lacerated soft tissue can occur, even under close patient supervision. Factors that may hinder the learning process for the resident include concerns of harming the patient and increased performance pressure with watchful OR staff (nurses, surgeons). In addition, time constraints, such as impending oxygen desaturation, delay of the start of surgical case, and increased pressure to maintain the OR schedule, can interfere with the airway management learning process and limits opportunity for instruction and criticism.⁴⁹ Furthermore, students are rarely given a second chance if they fail the first time, especially if the patient is a difficult intubation. This further hinders the learning process for the student. Conversely, other procedures are simply not reasonable to practice on healthy patients, such as cricothyrotomy. Despite these limitations, the performance of various airway management skills in the elective patient or simulated setting are vitally important to the success in more urgent or unanticipated settings.

In a 2007 Chest article, Kory and associates ⁵⁰ evaluated the teaching of airway management in medicine residents, challenging the traditional belief of “learning by doing” for resident training. The authors hypothesized that the “see one, do one, teach one” method is not appropriate in high-risk, low-frequency events such as respiratory arrest and difficult intubation patients. Although most programs offer simulation technology, it is not yet a standard component of residency training programs. Studying scenario-based training (SBT) and computerized patient simulator (CPS) versus traditionally trained (TT), the authors found that SBT-trained and CPS-trained internal medicine residents performed better than TT internal medicine residents in airway management skills.⁵⁰ This study focused on internal medicine residents, but its basic principles can theoretically be extrapolated to the training of any medical specialty in difficult airway management.

Training using simulators can be helpful for more advanced airway skills such as FOI and the intubating laryngeal mask airway (ILMA). Simulation facilitates the learning process in airway management and also offers other advantages, such as no risk of patient injury. Simulation allows for the performance of multiple attempts and types of interventions, allowing for errors because patient harm is avoided. Interventions can be stopped for feedback from trainers, uncommon scenarios can be created for serial practice, and interventions can be repeated after feedback for reinforced teaching. Simulator training decreases the amount of time performing the actual task on patients. This is useful for new trainees, whose skills are generally limited, and reduces the potential for patient injury. Naik and associates ³³ show that acquired skills from a simple training model are transferable to the clinical environment. Compared with basic didactic training, those who trained with a basic model for FOI demonstrated a faster intubation time, improved intubation success rate, and better technique. Further discussion of the role of simulation in advanced airway management is discussed in Chapter 52.

Model trainings can also be beneficial for tasks that are infrequently encountered on actual patients. Kory and others ⁵⁰ studied the progression of two groups: medical students trained by the traditional method of experience as clinical opportunities arose vs. students trained through patient simulator and SBT. The simulator group outperformed the TT group.

Another option for practice in infrequently performed airway management techniques involves the use of recently deceased individuals. Advantages include the ability to practice invasive procedures such as cricothyrotomy in a realistic setting. Consent from family members is obtained for this practice. Olsen and colleagues ⁵¹ found that obtaining consent from family to perform postmortem procedures is a valid option. The most common reason for refusal is personal and religious beliefs. After consent in this study, a cricothyrotomy was performed by emergency medicine resident physicians, supervised by an attending physician.

To develop successful skills in airway management, anesthesia residents should use mannequins and simulators suitable for the intricacy of the training objective. Simple models are sufficient in gaining basic skills and knowledge. Once a trainee becomes more comfortable with the device or technique, more detailed models and simulators may be helpful in conveying more complex goals and objectives. At Penn State’s training program, anesthesia residents use mannequins for practice in cricothyrotomy. However, mannequin training alone is not sufficient for developing intubation skills or management of a difficult airway with most devices. One study showed that only 53 of 103 intubations by emergency medical technicians (EMTs), solely using mannequin practice, were successful, with many requiring more than one attempt.⁵²

Laryngoscopy and intubation are fundamental skills of all anesthesiologists. However, it is necessary to be proficient with other adjunctive airway management skills to have a variety of methods to secure a difficult airway successfully. Connelly and associates ⁵³ conducted a retrospective study of unanticipated difficult airways and found higher success rates with LMA and FOI, when compared to repeated direct laryngoscopy. National surveys of anesthesia programs find that more than one skill set is needed to be effective in managing a difficult airway. This is partly the result of the variation in accessibility of certain equipment from place to place.⁴³ In addition to basic laryngoscopy and mask ventilation, proficiency with FOI and ILMA use are both deemed essential in training.⁴⁹

Skill in providing ventilation through basic face mask skills is often overlooked during residency training. Effective mask airway can salvage a difficult intubation in emergency settings, but it is also used for adequate preoxygenation and to control ventilation as part of initial resuscitation. Areas of focus include proper mask selection, proper mask placement to provide a good seal, and proper neck extension and jaw thrust, to facilitate mask ventilation and prevent associated complications, such as gastric distention or aspiration, soft tissue injury, and corneal abrasions.⁵⁴ Equally important is the recognition of patient characteristics associated with difficult mask ventilation and use of an oral/nasal airway, when needed.

Laryngoscopy is a basic skill all anesthesia residents must acquire during their residency. A study of first-year anesthesia residents by Konrad and colleagues ⁵⁵ found that successful intubation increased rapidly during the first 20 attempts, and the learning curve reached 90% success rate after a mean of 57 attempts. However, even after 80 intubations, 18% of residents still required assistance. Mulcaster and associates⁵⁶ investigated skill with direct laryngoscopy by nonanesthesia individuals and found similar results, with an average of 47 intubation attempts needed to reach a 90% success rate. Mannequin training alone was not sufficient to adequately prepare nonanesthesia individuals for successful direct laryngoscopy. A majority of the individuals studied had difficulties with direct laryngoscopy performed on patients despite 20 successful intubations on mannequins. Hirsch-Allen and coworkers⁵⁷ found that the year of training and type of residency were associated with multiple tracheal intubation attempts. Anesthesia residents had the lowest reintubation rate, regardless of their year of training. This important study emphasizes that a higher number of intubations is needed to obtain a 90% successful rate for nonanesthesia physicians who desire to master the technique of direct laryngoscopy and endotracheal intubation.

In a study of LMAs placed by EMTs, insertion was 100% successful in mannequins but only 64% successful in the field.⁵⁸ This emphasizes the performance of LMA insertion on live patients and deemphasizes the importance of mannequin training as a sole teaching tool.

Video-enabled technology is another tool in the airway management armamentarium ⁵⁹ and another vital skill that residents should acquire during residency training. Video-enabled airway technology includes the integration of existing intubation equipment (laryngoscope, fiberscope) with a video system, allowing the image to be projected onto a monitor. Recording the resident’s attempt at intubation enables supervising faculty to provide insight on the performance, allows for review and correction of technical inadequacies by guiding the resident’s hand during the attempt, and allows for feedback afterward. Instructors are able to visualize what the trainee sees during laryngoscopy or FOI. By doing so, the video system allows both mentor and student to share the same view of anatomy and to follow the progress of the airway management technique employed.⁶⁰

Video-enabled systems may be superior in the successful intubation of some difficult airway patients compared with conventional direct laryngoscopy.⁵⁹ Jungbauer and colleagues⁶¹ prospectively studied tracheal intubation of 200 patients with Mallampati scores of 3 or 4 using the Berci-Kaplan video laryngoscopy (Storz) system, versus direct laryngoscopy. The video system provided a superior view of the cords, had a higher success rate, had faster time to intubation, and required fewer optimizing maneuvers than direct laryngoscopy.⁶¹ Marrel and associates⁶² studied video laryngoscopy and direct laryngoscopy in 80 morbidly obese patients. They found that the view achieved with the video system was significantly better in 28 patients and duration of intubation shorter.

Numerous studies support the routine use of alternatives to direct laryngoscopy in the setting of failed and known difficult intubation. Studies support the use of salvage interventions in the setting of an unanticipated difficult intubation with a practiced alternative, because these are likely to be associated with better outcomes compared with persistent direct laryngoscopy. Video laryngoscopy is emerging as a vital tool in both anticipated and unanticipated difficult intubation.⁵⁹ Residents should be familiar and trained to use one or more of the commercially available video laryngoscopes during their training. Video laryngoscopes are necessary tools for difficult airway management when direct laryngoscopy fails and also serve as invaluable tools in teaching advanced airway management.