Displacement of the endotracheal tube caused by postural change: evaluation by fiberoptic observation.

Unexpected displacement of the endotracheal tube during anesthesia caused by postural change of the neck or passive compression by the mouth gag was investigated under transluminal fiberoptic observation. Twenty-two patients were divided into orotracheal and nasotracheal intubation groups according to the technical requirements of the planned oral and maxillofacial surgery. Under nasotracheal intubation, the mean length of displacement from the carina was 21 mm by extension of the neck, and 8 and 7 mm by lateral rotation of the neck to the right and left sides, respectively. Under orotracheal intubation, the mean length of displacement from the carina was 12 mm by extension of the neck and almost 28 mm with application of the mouth gag. To avoid accidental extubation or one-sided bronchial intubation during anesthesia, the tip (distal end) of the endotracheal tube should be located less than 32 mm from the carina before extension of the neck and more than 41 mm from the carina before application of the mouth gag.