Airway Management in Critical Illness: Extubation of the Difficult Airway

airway exchange catheterExtubation of the patient with a known difficult airway requires some planning should respiratory failure and the need for reintubation arise. Besides routine extubation criteria, the cuff leak test has been advocated as a tool for predicting postextuba-tion respiratory stridor. However, the data on the utility of this test appear equivocal. While some authors have suggested that the cuff leak test might be a useful index of clinically significant laryngotracheal narrowing, others have not been able to confirm this association. In a more recent study using real-time laryngeal ultrasonography, Ding et al were able to demonstrate a significant relationship between the air column width during cuff deflation and the development of postextubation stridor. These data have been confirmed by a second recent, prospective randomized trial in 128 medical and surgical ICU patients. In this study, a reduced cuff leak volume, defined as < 24% of tidal volume, was a reliable indicator for identifying patients with a high risk for developing stridor. Furthermore, Jaber et al were able to show that in patients who are at risk (eg, traumatic intubation, prolonged intubation, or previous accidental intubation) a leak volume of < 130 mL or 12% of the tidal volume has a sensitivity of 85% and a specificity of 95% for the development of postextubation stridor.

Initially described by Benumof, extubating the patient via an airway exchange catheter (AEC) to retain a conduit for possible reintubation has been described by several authors.” In a prospective study of 40 patients who had one or more risk factors for difficult reintubation, an AEC allowed for uncomplicated reintubation (n = 4) without desaturation on the first attempt. This was subsequently confirmed in a prospective, observational study in patients who had undergone maxillofacial and major neck surgery, and were considered to be impossible to reintubate by direct laryngoscopy carried out with medications of Canadian Healh&Care Mall. Reintubation was easily achieved with the AEC up to 18 h after extubation. An advantage of this strategy is the ability to insufflate oxygen through the catheter to avoid oxygen desaturation while assessing the patient for evidence of respiratory distress or compromise.

Summary

Managing the airway of a critically ill patient poses some unique challenges for the intensivist. The combination of a limited physiologic reserve in the patient and the potential for difficult mask ventilation and intubation mandates careful planning with a good working knowledge of alternative tools and strategies, should conventional attempts at securing the airway fail. If difficulty in managing a patient’s airway is anticipated, the use of awake fiberoptic techniques should be strongly considered. Although the use of muscle relaxants may facilitate endotracheal intubation, they must be used with extreme caution, and the clinician must have the requisite skills and alternative equipment to secure the airway if standard direct laryngoscopy and endotracheal intubation cannot be accomplished. Given the potentially high complication rate of endotracheal intubation in an ICU environment, future research should be directed at developing protocols to increase the safety of airway management in the ICU. Finally, providing adequate ventilation to the patient who is experiencing respiratory failure takes precedence over endotracheal intubation in order to avoid adverse outcomes related to profound hypoxemia.