Clinical application of acoustic reflectometry in predicting the difficult airway.

UNLABELLED Acoustic reflectometry, a noninvasive test that produces a length versus cross-sectional area map of the airway, has been used to identify difficult-to-tracheally intubate patients in a small retrospective case-control study. A critical airway volume of 40.2 mL separated those patients whose tracheas were impossible to intubate from those who were easily intubated. To determine if this technology was applicable for prospectively predicting difficult intubation and difficult ventilation in routine clinical practice, we performed a double-blinded, prospective cohort study. Our a priori hypothesis was that small airway volumes in adults (<40.2 mL) would predict absolute inability to intubate. We conclude that by use of acoustic reflectometry, there was no relationship between inability to intubate, poor glottic visualization, and multiple laryngoscopies with airway volume. IMPLICATIONS Acoustic reflectometry, a noninvasive test that uses sound to produce a length versus cross-sectional area map of the airway, was not able to predict inability to intubate, poor glottic visualization, and multiple laryngoscopies.