The conformity of an anatomically shaped endotracheal tube to the shape of the airway.

The conformity of a pre-shaped endotracheal tube to the shape of the airway during endotracheal intubation was studied from lateral radiographs in patients lying supine on the operating table, with the neck in the normal, extended and flexed positions. A computer programme calculated the anterior contour of the pre-shaped tube and the posterior contour of the airway as mean values of the original contours on the radiographs. The mean configuration of the airway in intubated individuals with a pre-shaped endotracheal tube was then presented in a standard coordinate system. The results were compared with the shape of the airway in non-intubated patients and in patients intubated with a standard endotracheal tube.