A method for comparing endotracheal cuffs. A controlled study of tracheal trauma in dogs

Damage to the trachea produced in dogs by large and small residual volume cuffs during 6 h of IPPV was compared using a specially designed endotracheal tube. The cuffs under evaluation were adjusted to exert similar average pressures on the tracheal wall, so that many of the variables believed responsible for tracheal injury were controlled. The true compliance of the cuff was measured with the tube inside and outside the trachea of the anaesthetized dogs. The maximum estimated pressure transmitted to the tracheal wall, derived from these compliance curves, was found to equal the peak airway pressure in the presence of a small air leak past each cuff. At various tracheal wall pressures there were only very minor differences in tracheal damage between the large and small residual volume cuffs tested.