Acoustic reflectometry detection of an endobronchial intubation in a patient with equal breath sounds.

Acoustic reflectometry can be used to distinguish between a tracheal and an esophageal intubation based on an area-distance profile. In a patient undergoing laparoscopic surgery, acoustic reflectometry was used to detect a bronchoscopically confirmed endobronchial intubation in the presence of equal bilateral breath sounds. An in vitro simulation suggests that in an endobronchial intubation, in the presence of a space leak between the tube cuff and the bronchus, an acoustic pressure disturbance can be transmitted to the opposite lung (causing equal breath sounds), without significant bulk airway flow (causing inadequate ventilation of the opposite lung).