High-volume, low-pressure cuffs. Are they always low pressure?

Ischemic tracheal complications due to the ETT cuff occur in approximately 10 percent of mechanically ventilated critically ill patients despite the use of high-volume, low-pressure ETT cuffs. Using a laboratory model, we studied the effects of airway pressure on three different ETT cuff designs, including two "low pressure" designs. Positive airway pressure acted on the "low pressure" cuffs to create a "self-sealing" effect that maintained tracheal occlusion despite airway pressures that exceeded cuff inflation pressure. Increases in airway pressure caused by decreased lung compliance resulted in higher cuff inflation pressures in all three groups, with the smallest increase occurring in the design that had the longest tracheal contact length. We conclude that the current high-volume, low-pressure ETT cuff design currently used does not guarantee low cuff pressure when high airway pressures occur, and an alternative design should be developed.