Chapter 53 Airway Management Instruction in the Operating Room
I Introduction
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.
Mort9 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.
Mort10,11 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, Mort11 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.
Mort12 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
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. Gaiser6 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
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.
Brimacombe21 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 Curry23 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.
Brimacombe21 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 associates26 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 Roberts29 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
Erb30 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 colleagues31 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).
Ovassapian32 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 53-3 Knowledge Base for Performing Fiberoptic Intubation (FOI)
Naik and coauthors33 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 colleagues34 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 colleagues13 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 associates35 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.
Related posts:
Physiologic and Pathophysiologic Responses to Intubation
Complications of Managing the Airway
Ultrasonography in Airway Management
Nonintubation Management of the Airway: Airway Maneuvers and Mask Ventilation
Separation of the Two Lungs: Double-Lumen Tubes, Endobronchial Blockers, and Endobronchial Single-Lumen Tubes
Monitoring the Airway and Pulmonary Function
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