The intracuff pressure (ICP) and lateral wall pressure (LWP) required to achieve a seal in circular, D-shaped, and U-shaped tracheal models were evaluated for seven different endotracheal tubes in 7.5-mm and 9.0-mm sizes. The effectiveness of the minimal leak technique of cuff inflation in protecting the tracheal wall from LWP was also assessed. ICP ranged from 17 to 300 torr, and LWP ranged from 1 to 120 torr at the point of minimal leak for all the tubes tested. ICP varied as much as 179 torr in one brand of tube on repeated minimal leak inflations of the cuff. The D-shaped tracheal model had the greatest influence on the ability of all the cuffs to create a seal and caused LWP to exceed ICP in some of the tubes studied. It is concluded that certain cuffs consistently perform better than others. However, no tube studied was able to perform satisfactorily in all the tracheal models. It was also found that the minimal leak technique of cuff inflation did not always protect the model wall from excessive pressures being exerted against it by the cuff.
Plunkett et al. (1981) studied this question.