Chapter 9. Flexible Bronchoscopic Intubation

9.1.1 How Did Bronchoscopic Intubation Develop?

The first recorded endoscopic tracheal intubation was reported by Murphy in 1967.1 In that case report, the trachea of a patient with Still's disease was successfully intubated through the nose using a flexible choledochoscope.1 The flexible fiberoptic bronchoscope was introduced into clinical practice in 1964, and although it was not developed for the purpose of airway management, its value as a device to facilitate endotracheal intubation was soon appreciated.2,3 A series of 100 tracheal intubations using the flexible bronchoscope was reported in 1972, with a success rate of 96%.4 However, utilization of flexible fiberoptic technology for endotracheal intubation remained limited among health-care providers throughout the 1970s and 1980s.5 Seventy-five percent of those who completed questionnaires at a series of fiberoptic bronchoscope workshops between 1984 and 1989 had either no or minimal experience with the technique.5 Following the publication of the ASA Guidelines on Difficult Airway Management in 1993,6 the use of flexible bronchoscopic intubation among anesthesia practitioners greatly increased7 and the technique has come to play a pivotal role in the management of the difficult airway.8

Although it has been advocated as the technique of choice in the management of the difficult intubation,9-12 this view is not universally shared and a reluctance to perform awake bronchoscopic intubation continues to occur.13,14 However, surveys from the United States, France, and Denmark published between 1998 and 2001 confirm the widespread use of flexible bronchoscopes particularly for management of the anticipated difficult airway.15-18

9.1.2 When Is Bronchoscopic Intubation Indicated?

The primary indication for bronchoscopic intubation is in the elective (or at least nonemergency) management of the anticipated difficult airway.

When endotracheal intubation is required and there has been a history of previous difficult intubation, or if difficult direct laryngoscopy is predicted on airway assessment, and in particular, when mask-ventilation is also predicted to be difficult, bronchoscopic intubation can be an invaluable alternative intubation technique. Although bronchoscopic intubation in this setting can be achieved under general anesthesia (GA), awake intubation maintains a wide margin of safety.19-21 In general, if airway compromise or respiratory distress exists, awake intubation similarly maintains a wide margin of safety.19 However, in this circumstance, the urgency with which airway control must be achieved and the extent of the airway compromise may limit the choice of technique, and bronchoscopic intubation may not be feasible or appropriate. In addition, incomplete local anesthesia of the upper airway makes bronchoscopic intubation more difficult, as does the presence of blood and secretions in the airway. Complete airway obstruction has been reported following the topical application of local anesthesia to the airway and suctioning in preparation for awake intubation in a stridorous patient with recurrent neck carcinoma and radiation therapy.22 Complete airway obstruction after application of topical local anesthesia to the upper airway was also reported by Shaw et al in a patient with a compromised airway secondary to goiter.23 Listro et al demonstrated a transitory but profound obstruction at the level of the glottis or supraglottis during forced inspiratory and expiratory vital capacity maneuvers that was produced in normal subjects with local anesthesia of the upper airway.24 Kuna et al and Beydon et al also found a decrease in upper-airway caliber following local anesthesia of the airway in normal subjects.25,26 Patients with severe airway obstruction due to edema or tumor must be approached with extreme caution if completion airway obstruction is to be avoided3 (see Chapter 3).

In the presence of potential cervical spine instability, no intubation technique has been shown to be clearly superior.19,20,27-31 However, movement of the cervical spine must be minimized during intubation if neurologic injury is to be avoided. Flexible bronchoscopic intubation (FBI) can be a valuable alternative in this setting and has been extensively used.28,32 Complete airway obstruction has however been reported during attempted awake bronchoscopic intubation in this patient population.32

FBI can also be used as an alternative to direct laryngoscopy in any patient for whom intubation is indicated, and in particular when a high risk of dental injury exists.3 In the setting of failed intubation by direct laryngoscopy or other techniques, FBI can be an invaluable option.

9.1.3 When Is Flexible Bronchoscopic Intubation Best Avoided?

Contraindications to FBI must be considered relative and weighed against the risks associated with alternative airway management techniques.19 Some measure of patient cooperation is required for awake FBI, and the total absence of cooperation may preclude this technique, as can bleeding in the airway and massive tissue disruption.3,19 Fixed laryngeal obstruction with stridor at rest implies a reduction in the caliber of the airway to 4.0 mm or less in diameter.33 FBI is unlikely to be successful in this setting and at best will produce a higher grade of obstruction when the scope is passed through the involved area. In this setting, a surgical airway (eg, awake tracheotomy) performed under local anesthesia is a better alternative.34 FBI is contraindicated when immediate airway control is necessary and the time required to complete the procedure is not available.7

Patient refusal in the adult population without psychiatric disease is exceedingly rare if an appropriate explanation of the procedure has been provided.

9.2.1 How Do Flexible Bronchoscopes Work? What Is the Best Instrument for Flexible Bronchoscopic Intubation?

The standard adult flexible bronchoscope remains unsurpassed as an instrument for bronchoscopic intubation in the vast majority of circumstances in the adult population. These bronchoscopes have a sufficient length (about 60 cm) to accommodate an endotracheal tube (ETT) ensleeved proximally while leaving an adequate distal segment for maneuverability. Shorter bronchoscopes tend to make FBI more difficult. A bronchoscope with an outside diameter of 5.9 to 6.0 mm will readily accommodate a 7-mm inner diameter (ID) ETT and has adequate stiffness to function well as a stylet over which to advance the ETT (see Figure 9-1).19,35 Bronchoscopes with thinner insertion cords tend to be more flexible and form a floppy stylet that is easily buckled away from the glottis as the ensleeved ETT is advanced into the airway (see Figure 9-2).20

The flexible bronchoscope consists of a proximal handle and a distal insertion cord or shaft. An umbilical or universal cord is attached to the side of the handle and connects the bronchoscope to an external light source (see Figure 9-3). Modern flexible bronchoscopes include fiberoptic bronchoscopes, video bronchoscopes, and hybrid designs. Flexible fiberoptic bronchoscopes are also available with a battery-operated light source, which greatly improves portability. The handle of the bronchoscope is fitted with a lever which controls flexion of the tip of the scope (the bending section)11,36 in a single plane; the movement of the tip being produced by two wires which connect the control lever to the tip of the scope (see Figure 9-3).11 The handle also contains the proximal port of the working channel which extends distally to the tip of the scope. This channel can be used to pass various instruments into the airway and can be used for irrigation, administration of medications, and suction. Oxygen insufflation has been used via the working channel; however gastric rupture has been reported with this technique.37 Light is transmitted from the external light source to the tip of the insertion cord via a fiberoptic bundle made up of thin glass rods (see Figure 9-4).11,36,38 In the flexible fiberoptic scope, light reflected from the object being viewed is focused by a lens located at the tip of the insertion cord onto the distal end of a second fiberoptic bundle which then transmits the image to a second lens located in the eye piece.11,36 The glass fibers in this image transmission bundle remain in the same relative location along the length of the bundle (coherent bundle) such that a mosaic image is accurately reconstructed at the eye piece.11,36 The image seen through the scope is focused by means of a control located in the handle. In the video bronchoscope, a charged coupled device or silicone chip is located at the distal tip of the insertion cord and is used to sense and transmit the image (see Figure 9-5).36 The image data are then transmitted electronically through the bronchoscope to an external video processing unit.36 The image is then displayed on a screen and can be printed, stored electronically, or transmitted to a remote location.36 A video camera can be coupled to the eye piece of a conventional fiberoptic bronchoscope. However, the image obtained is inferior to that provided by the video bronchoscope.36

Bronchoscopes are produced by a number of different manufacturers and are available with insertion cord diameters ranging from 2.2 to 6.3 mm.36 In general, minimizing the discrepancy between the outside diameter (OD) of the bronchoscope and the internal diameter (ID) of the ensleeved ETT facilitates passage of the tube through the larynx over the scope.2,3,20,39-45 Bronchoscopes with smaller diameter insertion cords have allowed FBI to be performed in the pediatric population, and very thin scopes such as the Olympus BF-N2O with a shaft diameter of 2.2 mm can be used in infants. However, use of pediatric bronchoscopes to perform FBI of the adult in general makes the procedure more difficult.20 The use of a pediatric bronchoscope to perform awake intubation in the adult with severe upper-airway obstruction may be complicated by complete obstruction and must be approached with great caution.3,22,34,46,

Bronchoscopes are delicate instruments and must be handled with care if damage to the instrument is to be avoided. Damage to the bronchoscope is not only costly to repair but it also means that the scope is unavailable for clinical use for a period of time.11 Striking the distal tip of the insertion cord against a hard surface or excessive bending or twisting of the shaft of the scope can damage the lens and fiberoptic bundles, respectively.36 If the external shaft of the insertion cord or the working channel wall is punctured, fluids can enter the inside of the scope and lead to a degradation or loss of the image transmitted.36

Flexible bronchoscopes with shaft diameters of 3.5 to 4.0 mm can readily be passed through the lumen of a #35-Fr or larger double-lumen tube and are invaluable for the precise tube placement required for lung isolation.

9.2.2 How Are Flexible Bronchoscopes Disinfected?

In general, the issue of sterilization of bronchoscopes is addressed by infection control and risk management personnel in each health-care facility.36 Specific recommendations for sterilization are also provided by each manufacturer.11,36 A typical sterilization process is as follows:

Immediately following a bronchoscopic procedure, a premixed enzymatic solution is suctioned through the working channel(s) of the bronchoscope and the instrument is wiped down with a lint-free cloth saturated with the premixed enzymatic solution. This is considered to be a "preclean setup" in the sterilization process and is performed at the bedside. The scope is then transferred to the sterile processing department where a leak tester is connected to the umbilical cord or handle and the inside of the scope is pressurized with air. The scope is then immersed in a water bath for 30 seconds and observed for escaping bubbles. The scope is removed from the water bath, the leak tester disconnected from the pressure source, and the scope allowed to vent at atmospheric pressure before the tester is disconnected from the self-sealing port. The scope is then placed in a predetermined concentration of an enzymatic solution and the working channels and external controls manually cleaned with appropriate brushes. The working channels are also flushed with the enzymatic solution followed by water and air. The scope is then immersed in a solution of peracetic acid using specially designed equipment that ensures flow through the working channels. These channels are subsequently irrigated with air and alcohol before the scope is dried manually and with an air flush. The sterilization process requires about 50 to 60 minutes to complete. If the scope is not reused within 1 week of the sterilization process, the sterilization is repeated. Glutaraldehyde, hydrogen peroxide, and ortho-phthalaldehyde (Cidex OPA) can also be used for disinfection of bronchoscopes.36 Ethylene oxide (ETO) sterilization is also an effective agent for sterilization of bronchoscopes, although the process requires about 18 hours to complete. When the scope is gassed, an ETO cap must be attached to the leak tester port to permit the gas to enter the scope and thereby equalize internal and external pressures.11

Recently, it has been shown that routine cleaning and autoclaving do not remove protein material, including prions, from reusable airway devices,47 and concern has been expressed with respect to the possible transmission of infection with subsequent usage.48 Currently there is no information available with regard to the cleaning of bronchoscopes such that the absence of protein deposits can be ensured. Similarly, the risk of cross-contamination of patients following a standard cleaning procedure for the flexible bronchoscope is unknown.

9.3.1 How Is the Bronchoscope Maneuvered? What Are the Key Aspects of Technique for Fast, Successful Bronchoscopic Intubation?

The bronchoscope is most easily maneuvered by holding the handle of the scope in the palm of the dominant (usually right) hand with the thumb placed on the flexion lever (see Figure 9-6). The fingers should comfortably encircle the handle of the scope and the index finger can be used to activate the suction mechanism, although if antisialogogues are used, suction is rarely required during FBI. When the scope is held such that the flexion lever is in the 6 o'clock position, moving the lever downward (toward the shaft of the scope) flexes the tip of the scope upward toward the 12 o'clock position. Conversely, moving the lever up toward the proximal aspect of the handle flexes the tip downward toward the 6 o'clock position (see Figure 9-7). Movement of the flexion lever (thumb flexion) then flexes the tip of the scope in a single plane. To flex the tip in any other plane, the entire instrument must be rotated clockwise or counterclockwise using the wrist and hand holding the handle of the scope. This wrist rotation is the second important and perhaps not intuitively obvious movement required when manipulating the bronchoscope during FBI (see Figures 9-8A and B). The tip of the bronchoscope can then be manipulated to view objects in any plane within the scope's field of vision by a combination of wrist rotation and thumb flexion. Many bronchoscopes have a triangular marker or divot7,49 located at the 12 o'clock position at the periphery of the scope's field of vision (see Figure 9-9). This marker helps the practitioner maintain spatial orientation as the tip of the scope always flexes in the diametrical plane of the marker. When a video camera is coupled to a fiberoptic bronchoscope, the divot must be adjusted to the 12 o'clock position (opposite the flexion lever on the handle) to maintain correct orientation.49 The practitioner's nondominant (usually left) hand holds the shaft or insertion cord of the bronchoscope a few centimeters proximal to the tip with the forearm pronated (see Figure 9-10). The shaft should be held lightly between the thumb and index finger, and stabilized between the ring and middle finger or some other combination of digits. The hand that holds the distal shaft of the scope must feed the scope forward into the airway in a controlled manner without excessive (shaky) movement that can make visualization difficult.

Generally it is easier to rotate the bronchoscope using the dominant (usually right) hand positioned at the handle. The nondominant hand holding the distal aspect of the shaft must however allow the shaft to rotate, and therefore the shaft cannot be gripped tightly. If the distal aspect of the shaft is held tightly, rotation at the handle twists the insertion cord, the scope fails to go in the desired direction, and the components in the shaft can be damaged. Although rotation of the scope is usually more easily controlled by the hand positioned at the handle, the nondominant hand holding the distal shaft can also be used to rotate the instrument. In that maneuver, the hand at the handle must follow the movement and allow the entire instrument to rotate as a single unit, or again, twisting of the shaft will occur and the scope fails to go in the desired direction (see Figures 9-8A and B). As experience is gained in handling of the scope, the shaft does not need to be held taut to maneuver the tip. However, holding the shaft of the scope relatively straight can be useful to maintain orientation and control movement. The most important concepts to master are thumb flexion and wrist rotation. In addition, during FBI, movements of the scope (flexion, rotation, and forward feeding) should be small, slow, and deliberate. Oversteering of the scope is a common error.

The ETT can be precut to a desired length to maximize the length of the insertion cord beyond the tube and thereby optimize maneuverability.19 The inside of the tube can be lubricated using lidocaine spray or sterile water. The tube is then ensleeved proximally and fixed to the handle with a single piece of easily removable tape or an elastic band (see Figure 9-11).19 A lubricant jelly placed on the cuff of the tube may facilitate glottic entry. Lubricating the shaft of the scope is unnecessary and makes it difficult to handle.

9.3.2 Is Bronchoscopic Intubation More Easily Performed from the Head of the Bed or from the Patient's Right Side? What Instructions Should Be Given to the Patient during the Procedure?

Awake FBI can be performed with the practitioner standing at the head of the bed, and for those who are most familiar with visualization of the airway by direct laryngoscopy, this position preserves the spatial orientation of the airway structures as they are viewed through the scope.19,20 However, this position requires the practitioner to negotiate an S-shaped curve to the trachea (see Figure 9-12) and the patient to be supine or nearly supine. Standing at the patient's right side facing cephalad facilitates negotiation of the natural C-shaped curve of the airway (see Figure 9-13) and permits easy visualization of patient monitors, and as eye contact can be readily maintained this position may be less intimidating for the patient.19,20 The patient may be supine or in the semi-sitting or sitting position.20 The semi-seated or sitting position may also be less intimidating for the awake patient and may better maintain the patency of the pharyngeal lumen.20,50 Extension at the atlanto-occipital joint moves the epiglottis anteriorly away from the posterior pharyngeal wall and facilitates passage of the bronchoscope through the pharynx.3,20,45,51,52 Neck flexion, however, tends to produce pharyngeal obstruction and can make FBI more difficult.20,51-53

For awake oral FBI, the author prefers to be positioned at the semi-sitting or sitting patient's right side (see Figure 9-14). The light source is to the practitioner's left, and the video screen is located in front of or slightly to the left of the practitioner. Oxygen can be administered by nasal prongs. An assistant is positioned at the patient's left side and provides gentle tongue traction using a piece of gauze.20 The bronchoscope can be focused on printed material prior to insertion. Use of a bite block tends to push the tongue posteriorly and cephalad into the oropharyngeal isthmus, can make passage of the scope more difficult, and if adequate local anesthesia has been achieved, is not necessary.20 The lens can be defogged using silicone solution or simply by holding the tip of the scope in warm water, or against the buccal mucosa for a few seconds to warm it and thereby prevent condensation.19,20 The scope should be inserted into the oral cavity to the level of the dental arches in the midline, and then advanced a few centimeters posteriorly over the dorsum of the tongue following the midline groove toward the first midline landmark, the uvula, seen in the superior aspect of the scope's field of vision (see Figure 9-9).20 Gently resting the hand holding the shaft of the scope on the patient's chin may help keep the scope in the midline.20,45 If the uvula is in contact with the dorsal aspect of the tongue, the patient can be instructed to take a deep breath, thereby elevating the uvula and opening the oropharyngeal isthmus.19,20 The scope is then advanced slowly forward just past the uvula and flexed caudally to visualize the second midline landmark, the epiglottis, seen inferiorly in the scope's field of vision (see Figure 9-15).19,20 If the epiglottis is oriented posteriorly or is in contact with the posterior pharyngeal wall, the awake patient can again be instructed to take a deep breath and thereby move the epiglottis anteriorly to create an air space through which to pass the scope.19,20 The scope is then passed, posterior to the epiglottis to visualize the third midline landmark, the vocal cords (see Figure 9-16).19,20 If the bronchoscope is passed behind the epiglottis in the midline, then it is naturally lined up for the approach to the larynx. Conversely, if the bronchoscope is off midline at the level of the epiglottis, the approach to the larynx can be much more difficult. The scope is then advanced in the midline through the glottis and positioned proximal to the carina.19,20 As the scope is advanced through the larynx, the patient is again instructed to take a deep breath to maximally abduct the vocal cords and thereby facilitate passage of the scope. As the bronchoscope is passed from the level of the dental arches to the trachea, flexion and rotation movements should be small and deliberate such that the scope can be kept in the midline and advanced along the C-shaped curve analogous to staying in a given lane during highway driving using small movements of the steering wheel. Unnecessary touching of the mucosa by the bronchoscope should be avoided. Having positioned the tip of the bronchoscope in the mid to distal trachea, the practitioner should then look directly at the patient and advance the ETT over the scope being careful to aim for the midline and to follow the natural curve of the airway (see Figure 9-14).19,20 The bronchoscope must be kept stationary as the tube is advanced9 in order to avoid inadvertent contact with the carina, cannulation of a main stem bronchus, or premature removal of the scope from the trachea. Again, as the tube is advanced, the patient should be instructed to take a deep breath to move the epiglottis anteriorly away from the advancing tube and to maximally abduct the vocal cords.19,20 The correct intratracheal position of the ETT can be confirmed endoscopically before the scope is removed.19,20 However, the presence of both the bronchoscope and ETT in the trachea produce a degree of airway obstruction that can be distressing for the awake patient, and the bronchoscope should be removed expeditiously once the ETT is in proper position. Correct position can be further confirmed by listening to and feeling gas exhaled via the ETT and by capnography.

9.3.3 How Can Difficulty in Passing the Ensleeved Endotracheal Tube into the Trachea over the Flexible Bronchoscope Be Minimized?

Difficulty in passing the ensleeved ETT through the larynx has been variously reported to occur in 5% to 90% of FBIs,42,54-58 and has occurred in awake patients, as well as those under GA, and with both the nasal and oral routes of tracheal intubation. During oral FBI, as the tube is advanced with the concave aspect of the tube facing anteriorly and the bevel facing toward the patient's left, the leading edge of the tube may meet resistance at the right arytenoid or aryepiglottic fold (see Figure 9-17).56,59,60 Rotation of the tube 90 degrees counterclockwise orients the bevel posteriorly and the leading edge into the 12 o'clock position and has been advocated to improve passage of the ETT through the larynx.60-63 Rotation of the tube counterclockwise may also keep the leading edge in closer contact with the bronchoscope and provide less of a gap between the two with which to catch a laryngeal structure.64 During nasal FBI, it has been postulated that the tube tends to impinge on the epiglottis.56,60,64 However the usual point of obstruction during nasal tracheal intubation may also be the right arytenoid.64 Improved success rates have been reported for glottic cannulation during nasal FBI, using a 90-degree counterclockwise rotation of the tube.56 Conversely, nasal FBI performed with the bevel up has also been advocated such that impingement on the epiglottis may be avoided.63 In addition to the right arytenoid and epiglottis, impingement can occur at the posterior pharyngeal wall or other laryngeal structures.58 The larger the discrepancy between the outside diameter of the bronchoscopic stylet and the internal diameter of the ensleeved ETT, the greater is the chance that the tube may impinge on laryngeal structures and resist entry into the trachea (see Figure 9-18).2,3,20,41,42,59 Therefore this discrepancy should be minimized by choosing the largest bronchoscope which will easily fit into the ETT to be used.20,44,45 In the adult, a bronchoscope with an outside diameter of 5.9 to 6.0 mm works well when used with a 7.5 to 8.5-mm ID ETT. When the combination of a relatively large bronchoscope and an ETT are both present in the trachea, the practitioner must be aware that a degree of airway obstruction has been produced40 and the bronchoscope should be removed without delay following tube placement and confirmation. If the bronchoscope must remain inside the tube positioned in the trachea for a relatively long period as during diagnostic or therapeutic bronchoscopy, then the concentric airway remaining must be adequate to permit ventilation to occur.20,40,65 Wire-reinforced spiral tubes are more flexible than polyvinyl chloride (PVC) tubes and may more easily follow the curve of the bronchoscope as it passes through the larynx.20,59,65-68 Although flexible wire-reinforced tubes were reported to be associated with a lower rate of impingement in the larynx than a standard tube,66 subsequent studies reported frequent laryngeal impaction with spiral tubes.54,55 Various methods to minimize the discrepancy between the outside diameter of the bronchoscope and the ID of the ETT have been proposed. These include the interposition of a smaller ETT between the scope and the larger ETT to be positioned in the trachea (see Figure 9-19),39,68 or the use of a sleeve such as an airway exchange catheter,68 split nasogastric tube,69 or a custom-designed conical-shaped PVC sleeve.70 The use of a Cook Airway Exchange Catheter passed alongside the bronchoscope through the ETT into the trachea to centralize the tube and facilitate glottic cannulation has also been reported.71 Preformed PVC ETTs can also be warmed to increase flexibility.11,19,20 Laryngeal cannulation with the ensleeved ETT may also be facilitated by using a tube with a modified tip design.19,20,59,61 The silicone wire-reinforced tube for the intubating laryngeal mask airway (ILMA) is reusable and has a soft hemispherical bevel that has a leading edge in the midline (see Figure 9-20).59 Greer et al found that the incidence of difficulty in passage of the ETT was significantly less using the IMLA tube as compared to the flexometallic tube during oral FBI under GA.59 Barker et al found the Intravent Orthofix ILMA tube to be superior to both the reinforced and standard PVC tubes during nasotracheal intubation under GA.54 All 15 Intravent tubes were easily passed through the larynx on the first attempt, whereas difficulty in passing the ensleeved tube was encountered in 8/15 in the standard-tube group, and 6/15 in the flexible-tube group.54 The Parker Flex-Tip tube shown in Figure 9-21 has a flexible tip that points toward the center of the distal lumen and the convex side of the tube.42 Kristensen has reported a greater incidence of initial success with passage of the tube through the larynx as compared to a standard PVC ETT in a series of 76 patients who underwent oral FBI under GA.42 A higher cuff pressure was required with this Parker Flex-Tip tube to establish a seal. However, in a recent randomized prospective study involving 111 patients with difficult airways or unstable cervical spines, Joo et al did not find any significant difference in the success rate between the Parker Flex-Tip tube and the PVC tube for awake oral FBI.72 Difficulty in advancing the ETT through the larynx may be encountered as well in the awake patient without obtunded laryngeal reflexes.3

Difficulty with passage of the ETT through the larynx is exceedingly rare in the awake cooperative patient in the sitting position with adequate topical anesthesia of the airway, when an optimally sized bronchoscope is used relative to the ETT, and the tube is advanced during a deep inspiration.

9.4.1 Are Oral Intubating Airways Useful or Necessary?

Various oral intubating airways are available and can be used during FBI. The purpose of these airways is to keep the bronchoscope in the midline and align it with the glottic opening, displace the tongue anteriorly and the soft palate superiorly thus opening the pharyngeal space, and to protect the scope from bite damage.49,73

The Berman intubating pharyngeal airway, also known as the Berman breakaway airway (see Figure 9-22), is cylindrical and has a longitudinal opening along its side which permits its disengagement (breakaway) from the ETT.11 The maneuverability of the bronchoscope is limited when inside the airway, and if the airway is not in line with the glottis, visualization requires manipulation of the device.11

The Patil-Syracuse endoscopy airway (see Figure 9-23) is made of aluminum and is available in two sizes (adult and pediatric). A central groove is located on the lingual surface for the bronchoscope, but manipulation of the bronchoscope is restricted.47 An ETT will not pass through the airway.11

The Williams airway intubator has a cylindrical proximal half, whereas the distal half of the device has an open lingual surface (see Figure 9-24).11,49 The airway is available in two sizes (90 and 100 mm ID) which admit 8.0 and 8.5 mm ID ETTs, respectively.11,49 Manipulation of the bronchoscope inside the airway is limited.11 If the distal aspect of the airway is not aligned with the glottis, visualization of the vocal cords can be difficult.11,49

The Ovassapian fiberoptic intubating airway has a flat lingual surface at the proximal half of the device which minimizes its movement (see Figure 9-25).11,49 The distal half of the airway has a wide curve designed to prevent the tissues of the anterior pharyngeal wall from moving posteriorly. The posterior distal aspect of the airway is open.

A split Guedel airway has also been used for FBI.10

Randall et al found that the Berman airway was superior to the Ovassapian fiberoptic intubating airway during FBI.74 However, only 1 of 63 bronchoscopies failed using the Ovassapian airway. Greenland et al compared the Williams airway intubator and the Ovassapian fiberoptic intubating airway in 60 Asian patients who underwent oral FBI under GA.73 They reported that the Williams airway provided an unobstructed view of the glottis in 68.3% of cases, whereas the Ovassapian airway provided an unobstructed view in 25%. Four bronchoscopies failed using the Williams airway and 26 using the Ovassapian airway. Intubating conditions with either airway were similar when the glottis was visible.73 Asai and Shingu suggest that it may be better to remove an airway intubator after the bronchoscope has been positioned in the trachea as it may interfere with the advancement of the ETT.39

Airway intubators can be used to facilitate FBI. However, FBI can be rapidly achieved without the use of these devices and the emphasis should be on the development of skill with bronchoscopic manipulation and regional anesthesia of the airway.

9.4.2 Is Nasal Bronchoscopic Intubation Easier? Which Nostril Is the More Appropriate for Intubation?

If the nasal route is chosen for FBI, an attempt to identify the more patent nostril can be made by asking the patient to assess airflow through each nasal cavity in turn during exhalation, and by palpating airflow from the nostril.75 However, these simple diagnostic tests have been shown to have a failure rate of about 45%.75 Some degree of nasal obstruction can be present in the absence of a history of nasal trauma, surgery, or obstruction and can interfere with the attempted passage of a nasal tube. The mucosa over the turbinates is easily traumatized.75 Endoscopic examination of the nasal cavity may be helpful in identifying the more appropriate nostril for intubation.75 Administration of a nasal vasoconstrictor may also increase the caliber of the nasal airway. In the absence of a history of nasal obstruction, it is controversial whether the left or right nostril should be used for nasal intubation as it is not known whether the bevel or the tip of the tube is more responsible for potential damage to the nasal mucosa (see also Blind Nasal Intubation section in Chapter 11).

During nasal FBI, either the ETT or the bronchoscope can be passed initially through the nasal cavity.2,19,20,38 If the tube is passed first, it can be advanced along the floor of the nose using a gentle alternating clockwise-counterclockwise motion to facilitate its passage until the tip of the tube exits the choana to enter the nasopharynx.2,20 The scope can then be passed through the lubricated tube and as it exits the distal aspect of the tube, the glottis is usually in view (see Figure 9-26). If on exiting the tip of the ETT the view is obstructed, the tube may be in contact with the pharyngeal mucosa or the tip of the scope may be covered with blood or debris. The scope can be removed, the tip cleaned and warmed, and then replaced into the tube. If on exiting the distal aspect of the tube still no recognizable structures are visualized, then the scope and tube should be slowly retracted together until pharyngeal or laryngeal landmarks (the uvula, epiglottis, or vocal cords) are identified.19 If the epiglottis is oriented posteriorly against the posterior pharyngeal wall, the patient can be instructed to take a deep breath and thereby move the epiglottis anteriorly and create an adequate airspace for the scope to pass behind it without touching mucosa and losing the visual field.20 The flexible bronchoscope is then advanced into the trachea and the ETT advanced over the scope as for oral intubation during a deep inspiration, optimally with the patient in the semi-sitting or sitting position.19,20 Alternatively, the flexible bronchoscope can be passed through the nasal cavity initially under endoscopic vision and then on into the trachea and the ensleeved ETT passed over the scope (see Figure 9-27). On advancing the ETT over the flexible bronchoscope, the leading edge of the tube may impact on the laryngeal structures and resist further advancement.56 The most likely site of impingement during nasal FBI is controversial.60,64 Rotating the tube such that the bevel faces anteriorly,63 or posteriorly,56 or advancing with a twisting motion20,40,60 may facilitate glottic entry. A lubricated nasopharyngeal airway can be inserted temporarily into the nose before subsequent insertion of the ETT to explore the nasal cavity such that an appropriately sized ETT can be chosen.20 Further decompression of the nasal mucosa may also be thereby achieved76 and trauma due to the more rigid ETT may be reduced. Alternatively, a nasopharyngeal airway split longitudinally can be inserted into the nasopharynx and used as a guide through which to pass the bronchoscope.20,76 The split nasopharyngeal airway can then be removed before subsequent passage of the ETT. On occasion, the caliber of the nasal cavity may be such that it will permit passage of the ETT but not the bronchoscope through the tube due to external compression of the tube.19,20 Conversely, the nasal cavity may permit initial passage of the scope but not the tube over the scope.19,20 In this circumstance, it may be necessary to use a smaller scope, a smaller tube, the other nostril, oral intubation, or another means of airway management.

Nasotracheal intubation produces less stimulation of the gag reflex3,7,57 and requires less patient cooperation, but is generally more uncomfortable for the awake patient. If the nasal cavity can be readily cannulated, it is technically somewhat easier than oral FBI.

Nasotracheal intubation has been considered to be contraindicated in the presence of a coagulopathy, intranasal abnormalities, paranasal sinusitis, extensive facial fractures, and basal skull fracture.77-80 Conversely, basal skull fracture has been said not to be a contraindication to nasotracheal intubation.77 Complications peculiar to nasotracheal intubation include epistaxis,29,78,80-83 damage to the nasal or nasopharyngeal mucosa with creation of a false passage3,81 and potential abscess formation,78 bacteremia,3,29,80 damage to nasal polyps or adenoidal tissue with possible dislodgement and aspiration, nasal necrosis,3,29,78,80 sinusitis,29,78,80 and otitis.3,29,80 Minimal epistaxis has been reported in 11% to 40% of emergency nasotracheal intubations81,83 and moderate to severe bleeding in 7%.83 In a series of 99 patients undergoing maxillofacial surgery, nasotracheal intubation was associated with mild epistaxis in 5 patients and bleeding sufficient to produce a visible accumulation of blood in the pharynx in 1 patient.82 Of 175 participants who underwent nasotracheal intubation at an awake bronchoscopic intubation training course, minor nasal bleeding was seen during endoscopy or after extubation in 20.84 None of these 20 participants required suction to clear the airway and the bleeding did not interfere with endoscopy.84

9.4.3 When Is Bronchoscopic Intubation under GA Indicated? What Are the Problems with This Technique?

FBI under GA can be performed as easily as intubation by direct laryngoscopy in patients with normal airway anatomy.3 Oral FBI has also been successfully performed following simulated rapid sequence induction (RSI),85 and FBI under GA has been used for training purposes.86,87 FBI of the anticipated and unanticipated difficult intubation under GA has also been reported, although some intubation failures did occur.10,88 This technique may be particularly useful in uncooperative patients.89

As consciousness is lost, loss of tone in the submandibular muscles allows the tongue and epiglottis to move posteriorly and potentially obstruct the airway at the level of the pharynx and larynx, respectively.90,91 The soft palate also approximates the posterior pharyngeal wall.90 The degree of airway obstruction produced is influenced by variations in airway anatomy, body habitus, and depth of coma.20,52 In the unconscious individual, this reduction in the caliber of the pharyngeal lumen can make endoscopic visualization more difficult.3,20,92 Contact of the bronchoscope lens with the mucosa results in loss of the visual field, and the practitioner's ability to maneuver past an epiglottis in contact with the posterior pharyngeal wall is limited.20,35,40,92 In the supine individual under GA, lingual traction with Duval forceps has been shown to move the tongue away from the uvula and soft palate better than the jaw thrust maneuver, whereas jaw thrust moved the epiglottis away from the posterior pharyngeal wall more effectively than tongue traction.91 Jaw thrust and tongue traction applied simultaneously opened the airway at the soft palate and epiglottic level in all patients studied.91 These combined maneuvers require two assistants.91 Intubating airways such as the Berman or Ovassapian airway can also be used to keep the pharyngeal airway open as well as to direct the flexible bronchoscope toward the larynx; however multiple manipulations may be required, the intubation may be prolonged, and failure can occur.91 Anterior displacement of the tongue base using the rigid laryngoscope may also improve visualization,2,3,20,35 as can placing the patient in the semi-left lateral position with the head turned to the left.93 If resistance is encountered in passing the ETT over the bronchoscope despite rotation of the tube, digital manipulation may be useful to facilitate glottic entry.45 An endoscopy mask fitted with a diaphragm permits endoscopy during positive pressure mask-ventilation94 and can be used in conjunction with an intubating airway.3,7,11,94 The nasotracheal route can also be used in the unconscious individual.2,92 In the presence of apnea or suboptimal ventilation, arterial desaturation imposes a time limit on bronchoscopic techniques.3,19,20 FBI of a patient under GA can be difficult and arterial desaturation can occur,95 although the technique has been used with high levels of success.85,88

9.5.1 How Useful Is Bronchoscopic Intubation in the Emergency Setting?

Immediate airway control in the emergency setting can be difficult using bronchoscopic techniques due to the presence of blood, emesis, or secretions in the airway.20,95-97 Poor preparation of the patient and lack of patient cooperation can also be problematic.3,20,95,98 FBI can nevertheless be a valuable option in selected patients such as those with confirmed or suspected cervical spine injury,97 those with anticipated difficult direct laryngoscopic intubation due to variant anatomy,97 and in the presence of airway pathology such as Ludwig angina,99 burn injury,100 or angioedema.96 Its use as part of a rapid sequence intubation technique has also been described.101 Complete airway obstruction has however been reported during attempted FBI in the presence of upper-airway compromise.22,32

Awake FBI has been advocated in the management of penetrating neck injury (see Chapter 34).101 However, this technique may only be feasible in cooperative stable patients who do not require immediate airway control.101,102 The optimal initial airway management approach in the patient with penetrating neck injury remains controversial.103,104 Mandavia et al reported a series of 58 patients with penetrating neck trauma who required emergency airway control.103 Of the 58 patients, 39 underwent rapid-sequence orotracheal intubation with a 100% success rate, 5 unconscious patients underwent orotracheal intubation by direct laryngoscopy without paralysis, and 2 underwent successful emergency tracheostomy.103 FBI was attempted in 12 patients. Three of these intubations failed, but all three were later successfully intubated orotracheally by direct laryngoscopy following RSI.103 Of 107 patients with penetrating neck trauma reported by Shearer and Giesecke, 8 patients underwent oral FBI with a 100% success rate.104 Eighty-nine patients underwent orotracheal intubation by direct laryngoscopy after RSI, six had a primary surgical airway, and four had blind nasotracheal intubation. Ninety-eight percent of the direct laryngoscopy RSI group was successfully intubated. The authors concluded that the technical and time constraints of FBI led them to prefer RSI and direct laryngoscopy, or a primary surgical airway, when an emergency airway was required.104

FBI has also been advocated for the emergency management of blunt injury to the airway, although reported experience is limited.105,106 Awake nasal FBI of a patient with unstable bilateral mandibular fractures in the semi-prone position has been reported.107 The patient was unable to tolerate the supine or sitting position due to airway obstruction.107 Successful awake bronchoscopic orotracheal intubation has also been performed via an LMA in a patient with massive oropharyngeal bleeding following blunt trauma.108 An attempt at FBI had failed due to blood in the airway, and an LMA was inserted to maintain gas exchange during a planned awake tracheotomy. Cuff inflation produced an unobstructed airway, resolution of respiratory distress, and permitted FBI through the LMA.108 Emergency FBI has also been performed successfully in patients with respiratory failure, congestive heart failure, altered consciousness due to stroke, overdose, head trauma, status asthmaticus, hematemesis, and partial upper-airway obstruction.95,97,98

Success rates of emergency FBI have been reported by various authors to be 72%,95 87%, 83%,97 and 75%.109 Visualization can be improved by pharyngeal suctioning.20,98 Insufflation of oxygen via the working channel of the flexible bronchoscope has been used to disperse secretions or vomitus and improve visualization.98 However, gastric rupture has occurred with this technique,37 and the potential for other barotrauma exists.3,19

In 1999, Levitan et al published a survey of devices used for difficult airway management in academic emergency departments in the United States.110 Of 95 programs who responded, only 64% had a flexible bronchoscope, and although the most commonly used alternative to intubation by direct laryngoscopy was the flexible bronchoscope, it was in fact rarely used.110 Only a small minority of patients requiring emergency endotracheal intubation need bronchoscopic techniques,97 and as a result skill maintenance is problematic. However, Desjardins and Varon have reported the use of awake FBI in a large proportion of their trauma patients, as well as the use of the rapid sequence bronchoscopic technique.101

9.5.2 Can the Flexible Bronchoscope Be Combined with Other Intubation Techniques?

FBI via the LMA has been described by a number of authors.2,3,11,111-117 A 7-mm ID ETT can be passed through a #5 LMA, and a 6-mm ID ETT through a #3 or #4 LMA.38,111 The LMA Classic Excel has a removable connector and an epiglottic elevating bar which facilitates intubation and permits the use of larger ETTs.112 A #7.5 mm ID-cuffed ETT can be passed through a #5 LMA Classic Excel and a cuffed 7.0 mm ID ETT through a #3 and #4 Classic Excel.112 An appropriately sized bronchoscope can then be passed through the ETT into the trachea and the tube advanced over the scope. The length of a #4 LMA is 20 cm from the proximal edge of the LMA adapter to the aperture bars,113 and the distance from the aperture bars to the cords is about 3.5 to 4.0 cm.11,114 A standard 6 mm ID ETT will therefore only be able to extend about 5 cm below the cords and will not provide an adequate length of ETT for satisfactory tracheal placement.11 However, a 6 mm ID microlaryngoscopy tube (MLT, Mallinckrodt, Hospimetrix Sdn Bhd, Selangor, Malaysia) with a length of 40 cm can be used to overcome this problem.115 Alternatively, a 6 or 7 mm ID nasal Ring-Adair-Elwyn (RAE) tube can be used, although the nasal RAE may need to be shortened by 2 cm to permit an adequate depth of intratracheal intubation by the flexible bronchoscope.114 The LMA can be removed over the ETT using a second tube to exert counter pressure on the ETT in the trachea to prevent its inadvertent dislodgement during removal of the LMA.116 The airway tube of the ILMA has a minimal ID of 13 mm and can accommodate any cuffed ETT size up to an 8-mm ID.117 FBI through the LMA and ILMA has been performed with the patient awake or anesthetized.3,11,118

The reusable intubating laryngeal airway (ILA), (Mercury Medical, Clearwater FL, USA) is similar to the LMA both in its functionality and its insertion technique.111 It has several advantages over the LMA Classic: the circuit connector is removable; the shaft is shorter; and there are no aperture bars.111 A cuffed #7.5 mm ID ETT can be passed through a #3.5 ILA and a cuffed #8.5 mm ID ETT through a #4.5 ILA. Wong and McGuire reported successful intubation through the ILA using regular ETTs with and without bronchoscopic guidance.111

FBI can also be accomplished by passing a pediatric flexible bronchoscope with an ensleeved Aintree intubation catheter (AIC, Cook Medical Inc. Bloomington, IN) into the trachea through an in situ LMA Classic. The AIC is an ETT exchange catheter which has an internal diameter of 4.8 mm, an external diameter of 6.5 mm, and a length of 56 cm.119 Introduced in 1996, it was designed to facilitate FBI through an LMA Classic.120 The AIC can be ensleeved proximally over a 4.0 mm flexible bronchoscope such that the distal 3 cm of the shaft, the bending section, of the scope is free. The scope with the ensleeved catheter can then be passed through the LMA into the trachea. The scope can then be removed leaving the AIC in the trachea. The LMA can then be removed and an ETT ≥7.0 mm ID passed into the trachea over the AIC. The AIC is then removed. A Rapi-Fit adapter supplied with the AIC permits ventilation through the catheter if this becomes necessary119,120 Ventilation can also continue through the LMA during the FBI.120 Atherton et al reported that the experienced endoscopist could master the technique after four intubations and those inexperienced in FBI after six intubations.120 Zura et al reported a case of failed intubation by direct laryngoscopy and GlideScope in which the trachea was successfully intubated bronchoscopically using a #5 LMA Unique, an ensleeved AIC, and a 7.5 mm ID Parker Flex-Tip ETT.121 Avitsian et al reported a case of inadvertent tracheal extubation intraoperatively during cervical spine decompression.122 Bronchoscopic reintubation was accomplished using an LMA Classic and an AIC while maintaining in-line stabilization.122 Higgs et al reported a series of patients with difficult direct laryngoscopy who were successfully intubated bronchoscopically using an AIC and LMA.123 In five of these cases attempted intubation by DL had failed. The authors also note that the consultant in charge of one of the cases anesthetizes "more than 50" cervical spine cases per year primarily using this technique. Zura et al subsequently reported that at their institution they had achieved a 100% success rate with this technique in "more than 50" cannot intubate, can ventilate cases without complications.124 In a manikin study, FBI using the Aintree catheter through the LMA Proseal has been shown to be at least as easy and reliable as through an LMA Classic.125

In the Difficult Airway Society (DAS) guidelines for management of the unanticipated difficult intubation, FBI through the ILMA or the LMA Classic is included in Plan B (secondary intubation plan).126 Plan B is implemented when tracheal intubation by DL or an alternate technique of proven value in experienced hands has failed. The ILMA has proven to be a useful device in the management of the unanticipated difficult intubation;126 however blind intubation through the ILMA may require multiple attempts and esophageal intubation can occur.126 FBI through the ILMA has a higher success rate than blind techniques.126 However, techniques of insertion and intubation through the ILMA differ from those for the Classic LMA, and training and practice are essential if a high success rate is to be achieved while minimizing trauma in the unanticipated difficult intubation.126 The DAS guidelines state that FBI through the Classic LMA should be considered if an ILMA is not available, and note that a two-stage technique with the AIC can be used.126

The revised American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway in 2003 include the use of the LMA as an intubation conduit with or without bronchoscopic guidance in the alternative approaches to intubation.127

Higgs et al note that almost all international failed intubation guidelines include recourse to an LMA Classic to maintain airway patency.123 The authors also note that the ILMA is a specialized piece of equipment that is not universally available in all areas where anesthetics are administered or airway management occurs, and that it requires a distinct skill with its own learning curve.123 However, the LMA Classic is widely utilized, more likely to be immediately available, and easily inserted. The technique of FBI with an ensleeved Aintree catheter using the LMA as a conduit appears to be easy to learn and does not require a high level of bronchoscopic skill.123

In the unanticipated "cannot intubate, cannot ventilate" situation, an attempt to establish ventilation by insertion of an LMA Classic can be made while preparing to perform a cricothyrotomy. If ventilation can be established with the LMA Classic, it may be prudent to awaken the patient or proceed with a surgical airway as the clinical setting dictates. However, FBI can also be performed through the LMA Classic using an AIC.

FBI through the LMA Classic has been referred to as a "low skill bronchoscopic intubation"123 and has been regarded as a core skill that should be within the ability of all anesthesia practitioners after minimal training.123,128 The same can be said for all practitioners responsible for airway management.

The flexible bronchoscope can also be used to facilitate retrograde intubation (see Section 11.6.4).2,3,129 During retrograde intubation, the tip of the ETT being advanced into the trachea over the guide wire may impinge on laryngeal structures and resist further advancement.2,3 The flexible bronchoscope can be passed through the tube alongside the wire to visualize the glottis and then passed on into the trachea.2,3 The wire can then be removed and the ETT advanced over the bronchoscope.2,3 Alternatively, the wire can be passed in a retrograde direction through the working channel of the bronchoscope loaded with an ensleeved ETT.2,129 The bronchoscope is then advanced over the wire into the trachea and the guidewire removed.2,3 The ETT is then passed over the bronchoscope into the trachea.2,3,129

Blind nasotracheal intubation can also be assisted by the flexible bronchoscope.2,3 The bronchoscope can be passed through the contralateral nostril to visualize and thereby facilitate manipulation of the ETT into the trachea.2,3

9.6.1 What Are the Limitations and Complications of Bronchoscopic Intubation?

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.

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.

9.6.2 How Much Training Is Required to Develop Proficiency in Bronchoscopic Intubation? How Can the Training Be Acquired?

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.

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.

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

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

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

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.

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

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

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

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

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

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

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

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

Flexible bronchoscopic intubation is widely accepted as an invaluable alternate technique in the management of the difficult airway. It should be mastered by all anesthesia practitioners and other practitioners responsible for airway management.