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9.6.1 What Are the Limitations and Complications of Bronchoscopic Intubation?
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FBI in the presence of secretions, emesis, or blood in the airway is difficult and the applicability of the technique in the emergency situation is limited. Some measure of patient cooperation is also necessary. When both the bronchoscope and the ensleeved ETT are in the larynx or trachea, significant airway obstruction can be produced11,40 and can cause respiratory distress. Bronchoscopes are delicate, expensive instruments and require careful use if damage is to be avoided. The sterilization process is complex and requires time and resources.
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Although they are rare, complications associated with FBI can occur. These include laryngospasm,2,3 complete airway obstruction,22,23,32 local anesthetic toxicity,130 respiratory depression secondary to sedative overdose,3 loss of the endoscopy mask diaphragm into the airway,2,3 laryngeal trauma,131 pyrexia and rigors,132 and respiratory infection.84 The ETT is advanced blindly over the bronchoscope and may impinge on laryngeal or pharyngeal structures. Supraglottic swelling, pharyngeal hematoma, and vocal cord immobility and bruising have been reported after FBI.131 The ETT should be advanced gently over the bronchoscope, the gap between the ETT and scope diameters minimized, and the use of tubes with modified bevels may be considered. Additional studies are required to determine the mechanism of pharyngeal or laryngeal injury during FBI as well as their incidence and severity.131 In a series of 2031 FBIs, complications were limited to laryngospasm in 51, pain or hematoma secondary to cricothyroid injection in 33, gagging or vomiting in 8, and mild epistaxis in 70 who were nasally intubated.3 None of the cases of epistaxis required packing.
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9.6.2 How Much Training Is Required to Develop Proficiency in Bronchoscopic Intubation? How Can the Training Be Acquired?
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FBI is not a difficult skill to master; however, it requires familiarity with the anatomy of the upper airway, and dexterity in bronchoscopic manipulation. Awake FBI requires skill in regional anesthesia of the airway and gentleness on the part of the practitioner. Each step of the procedure must be planned in advance and methodically carried out. The ability to quickly and reliably maneuver the bronchoscope in a given direction is an absolute requirement for fast, successful, and safe FBI.
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Readily available intubation mannequins can be used to develop manual dexterity with the bronchoscope and with advancing the ETT over the scope. Nonanatomic models can also be used to develop bronchoscopic dexterity.
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Naik et al reported that a group of 12 novice residents who underwent bronchoscopic training using a Choose-the-Hole model significantly outperformed a similar 12 subject didactic group, when performance was evaluated during FBI of an anesthetized paralyzed patient.133 Marsland et al have described a nonanatomical modular endoscopic training system called Dexter.134 This system consists of a manikin, an image chart, a series of maps, and a structured training module. The objective is to endoscopically explore the mannequin and find the images placed inside it. Novice endoscopists took about 3.5 hours to complete the Dexter training modules and were then able to perform clinical endoscopy on awake subjects from mouth to carina in a mean time of 32.5 seconds.134 Marsland et al subsequently reported that 28 of 29 novice endoscopists were able to achieve bronchoscopic intubation proficiency within 4 hours of bench training with the Dexter system.135 Twenty seven of the 29 then demonstrated proficiency on clinical bronchoscopy to the carina.135
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Martin et al compared the effectiveness of the Choose-the-Hole model with the Dexter system in the development of endoscopic proficiency.136 Members of the authors' Department of Anesthesia were given initial didactic teaching. Initial endoscopic performance on an anatomical manikin was then assessed. The participants then practiced in a self-directed manner on one of the two models for a 2-week period, following which endoscopy skills were again measured on the manikin and then during clinical bronchoscopy from mouth to carina on each other. Participants in the Dexter group significantly outperformed the Choose-the-Hole group during clinical bronchoscopy. A positive correlation was also demonstrated between clinical and manikin performance scores. The authors concluded that Dexter is a more effective model for learning endoscopic dexterity than the Choose-the-Hole model, and that benchmark levels of endoscopic dexterity can be achieved without subjecting patients to novice learning curves.136
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Smith et al studied the learning curve of a group of 12 anesthesia trainees who underwent a supervised, structured, video-controlled training session utilizing a bronchial tree model followed by 20 supervised and coached nasal FBIs on anesthetized patients.137 The trainees were able to advance the scope to the carina within 2.5 minutes in 95% of the patients, and within an additional 2.5 minutes in the remaining 5%. The authors calculated that the half-life of the group learning curve was 9 endoscopies, and concluded that when using a videoscope under supervision, trainees were beginning to develop a reasonable level of proficiency in fiberoptic nasotracheal intubation after performing, on average, 18 intubations. Extrapolation of the learning curve suggested that 45 endoscopies would be required to approach expert times of 35 seconds for the procedure. Speed was felt to be related to the development of hand-eye coordination or dexterity. The authors noted great individual variation in skill development.137
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At the authors' institution a group of residents with no prior experience or training in FBI were given a brief slide show presentation on FBI, followed by expert demonstration on a manikin. Each resident was then coached by the instructor through a series of FBIs on the manikin. Each resident completed 50 supervised intubations within 1.5 hours. At the end of the session, all the participants had achieved a reasonable level of dexterity with the bronchoscope and were able to complete the intubation within about 30 seconds. Anecdotally, these skills were subsequently noted to be transferred to the clinical setting of awake intubation of the difficult airway.
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Rowe et al reported the use of a virtual reality bronchoscopic simulator for FBI training.138 Twenty pediatric residents who had no prior experience in bronchoscopy were randomized to a simulator or control group. All participants performed an initial FBI on a patient which was videotaped and graded. The simulator group (n=12) then underwent training on a virtual reality simulator. The residents in the simulator group practiced on an average of 17 virtual cases and spent 39 minutes on the simulator. They then performed a second awake intubation on a patient. The control group performed a second intubation without intervening training. The simulator group significantly outperformed the control group in all the variables measured (intubation time, number of mucosal hits, time viewing mucosa, and airway). There were no complications. The authors concluded that the bronchoscopy simulator was very effective in teaching residents the psychomotor skills required for flexible bronchoscopy.138
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FBI workshops can also be effective in improving skills.139 Patil et al reported a training course in local anesthesia and FBI using course delegates as subjects.140 Participants attended lectures, video demonstrations, and practical sessions using manikins and an artificial throat endoscopy model. Endoscopy was also performed on an instructor. All fifteen course participants then underwent local airway anesthesia and endoscopy. Nasal FBI was completed in 10 subjects. Nasal obstruction precluded intubation in three cases. Nasal anesthesia was inadequate in one case and the procedure was abandoned in one case who developed paresthesia of the hands and feet that could have been due to local anesthetic toxicity. The course overall was rated as excellent by all delegates and no delegate found the procedure to be unacceptable.140 In 2004 the same authors reported one subject who developed pyrexia and rigors about 6 hours after intubation and was treated with antibiotics.132
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Woodall et al subsequently reported a training course at which 200 anesthetists underwent airway endoscopy and attempted FBI under local anesthesia.84 One hundred and eighty delegates were intubated, 175 nasally and 5 orally, and 1336 endoscopies were performed. Intubation was abandoned due to nasal obstruction in 10 subjects, inadequate anesthesia in 8, symptoms suggestive of lidocaine toxicity in 1, and extreme agitation in 1. Minor nasal bleeding occurred in 20 subjects and symptoms that could be attributed to lidocaine in 71. Two subjects experienced rigors after the procedure and one developed a respiratory infection. Three delegates rated the intubation as distressing. The authors note that extreme caution is required when selecting subjects for a training course and concluded that the use of volunteers for this form of training carries risks and requires further evaluation.84
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FBI has been advocated as an alternate technique that may be used whenever tracheal intubation is indicated,3 and this FBI of normal airways under GA may be beneficial in learning to manipulate the bronchoscope and to advance the ETT over the scope.3,87,141 However, the use of nonroutine techniques may require discussion with the patient beforehand.142 Furthermore, the FBI of patients with normal airways under GA may not extrapolate well to the intubation of the difficult airway in the awake patient.141,143
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Cole et al reported FBI training of eight novice anesthesia residents using anesthetized paralyzed patients.86 The trainees were given two 1-hour lectures followed by a 20-minute hands-on workshop using a Choose-the-Hole model. Each trainee also performed one or two tracheal intubations in a manikin, and could practice using the manikin or model in their spare time. During the training period, each trainee performed 16 to 47 FBIs and 58 to 120 conventional rigid laryngoscopic intubations. Following the training period, bronchoscopic and laryngoscopic intubation skills were evaluated in a randomized single-blind prospective study. One hundred and thirty patients were randomized to either rigid laryngoscopic or bronchoscopic intubation. Each resident performed 5 to 10 rigid laryngoscopic intubations and 6 to 13 FBIs. There was one failed FBI and two failed rigid scope intubations. Successful FBI was achieved within 60 seconds of apnea in 52 of 71 cases. The average intubation time was less that 81 seconds for all residents and 5 of 8 residents achieved mean times of ≤60 seconds of apnea. There was no significant difference in the incidence of sore throat and hoarseness between the groups. There was no dental trauma.86
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Schaeffer et al have also reported a study of bronchoscopic training in anesthetized paralyzed patients.144 Five fourth-year anesthesia residents who had no prior experience in FBI performed tracheal intubation in 20 patients each in a random fashion either as an expert laryngoscopist or a bronchoscopic novice. The residents initially viewed two instructional videos and practiced on an intubation manikin until intubation times of ≤30 seconds were achieved. This required up to 20 supervised oral and nasal intubations. Each resident then performed nasal bronchoscopic intubations on 10 patients. The time to bronchoscopically identify the carina decreased from 64 seconds in each of the residents' first two intubations to 33 seconds in their last two intubations. The corresponding times to complete the intubation decreased from 96 seconds to 53 seconds. FBI was achieved on the first attempt in 98% of the patients. The incidence of sore throat, hoarseness, dysphagia, and hemodynamic change was similar between the groups.144
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Ideally, FBI should be demonstrated by a knowledgeable and skilled instructor.5 The learner should then be supervised until the principles of bronchoscopic manipulation are mastered. The availability of video bronchoscopes permit the instructor to easily coach the learner in the flexion and rotation movements required to properly steer the bronchoscope and appears to facilitate bronchoscopic skill acquisition.145 Independent practice is then required to further develop and improve psychomotor skills. A reasonable level of dexterity in manipulating the bronchoscope can be achieved within 3 to 4 hours of independent mannequin practice.5
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An acceptable level of technical expertise may be achievable after 10 FBIs in anesthetized patients146 and 15 to 20 awake FBIs in patients with normal anatomy.5 Smith and Jackson reported that trainees were "becoming reasonably proficient" after performing 20 FBIs in anesthetized patients in whom intubation was predicted to be difficult.147 It has also been suggested that 30 FBIs in conscious and anesthetized patients be performed before a practitioner is ready to handle the difficult intubation.148 The amount of experience and training required for safe and effective use of the flexible bronchoscope in the difficult airway is unknown;11,20 however an experience of 100 or more bronchoscopic procedures may be necessary to acquire expertise in this setting.5,11,20