To the Editor:—
One of the most problematic difficult airway management situations is the patient with a known difficult airway who is at risk of aspiration but who is unsuitable for awake tracheal intubation. We describe a new approach to this situation that involves the use of the ProSeal™ laryngeal mask airway (PLMA; Laryngeal Mask Company North America, San Diego, CA) and a reusable Eschmann endotracheal tube introducer or gum elastic bougie (GEB).
A 62-yr-old, 94-kg man with chronic obstructive pulmonary disease presented for an urgent laparotomy for a suspected perforated appendix. He had a well-documented history of failed laryngoscope-guided tracheal intubation (on two occasions due to poor laryngeal view) but successful facemask ventilation and laryngeal mask airway insertion. The patient insisted on airway management only after induction of anesthesia due to a previous bad experience with awake tracheal intubation. A decision was made to place a GEB using laryngoscope guidance either in the trachea using the bent end first (if any glottic structures could be seen) or in the esophagus using the straight end first (if no glottic structures could be seen) to facilitate insertion of an endotracheal tube or PLMA,1respectively. After 10 min of preoxygenation (time taken for end-tidal oxygen to be greater than 90%), the patient was induced with 0.5 mg alfentanil and 180 mg propofol, cricoid pressure was applied by a trained assistant, and 100 mg suxamethonium was administered. As predicted, neither the glottis nor the epiglottis could be seen, despite optimal laryngoscopic conditions. The GEB was therefore advanced with its straight end first along the right posterior pharyngeal wall toward the pyriform fossa. Cricoid pressure was released briefly (< 5 s) so that the GEB could be advanced through the hypopharynx into the proximal 10 cm of the esophagus.2The lack of the characteristic tactile sensation from the tracheal rings and the lack of resistance when inserted to length confirmed esophageal placement. A size 5 PLMA was then railroaded along its drain tube into the pharynx, and cricoid pressure was rereleased to allow the distal cuff to enter the hypopharynx. The cuff was immediately inflated with 20 ml air. The PLMA was fixed into position, the GEB was removed, and a gastric tube was inserted via the drain tube of the PLMA. Six hundred milliliters of bile-stained fluid was suctioned from the stomach. Ventilation was easy with tidal volumes greater than 1,000 ml without an oropharyngeal or esophageal leak and peak airway pressures of 25–30 cm H2O. Oropharyngeal leak pressure was greater than 40 cm H2O. Anesthesia management was otherwise uneventful, and there were no postoperative pulmonary complications.
In principle, this novel approach to difficult airway management should have a very high success rate because the failure rate for passage of a GEB into either the trachea or the esophagus should be very low, and the success rate for railroading an endotracheal tube or PLMA along it should be very high. If there is doubt about whether the GEB is in the trachea or esophagus, the PLMA should be railroaded first because esophageal placement is much more likely. If this does not provide an effective airway, it is likely that the GEB is in the trachea, and the PLMA should be removed and the endotracheal tube should be railroaded into position. In the unlikely event that both of these options fail, an alternative airway management strategy is required.
Although fiberoptic-guided intubation using a guide wire and airway exchange catheter is feasible using the PLMA,3we elected to complete the case with the PLMA. There is a moderate body of evidence (a cadaver study4and several anecdotal reports5–13) suggesting that a correctly placed PLMA provides protection against regurgitation. One group reported no episodes of regurgitation in 300 patients, as determined by litmus testing of the bowl after removal.14The efficacy of seal of the distal cuff against the hypopharynx, as determined in fresh cadavers,4is 40–80 cm H2O—more than enough to protect against passive regurgitation.15In addition, the process of exchanging the PLMA for a endotracheal tube may put the patient at risk of aspiration, and success is not guaranteed.
The safety of placing a GEB into the esophagus has not been established; however, there is some evidence that it is probably safe when conducted under direct vision and force is avoided, and there can be little doubt that it is justified in the failed intubation scenario. A recent study reported no occult blood on the GEB in 80 of 80 patients,16and we have used the technique on more than 6,000 occasions without any evidence of minor or major esophageal injury. Furthermore, GEBs are frequently misplaced into the esophagus with the bent end first (probably more likely to cause injury than with the straight end first) during failed intubation, but esophageal injury is rarely reported.17It is worth noting that the American Society of Anesthesiologists already recommends the use of the esophageal tracheal Combitube (Kendall Sheridan Catheter Corporation, Argyl, New York),18which is known to cause esophageal injury,19–21as an option in failed tracheal intubation. The development of an atraumatic esophageal guide for use with the PLMA and other extraglottic airway devices is currently under way and should make this approach even safer.
* Cairns Base Hospital, Cairns, Australia. jbrimaco@bigpond.net.au
