Changes in tracheal cuff pressure during respiratory support.

Tracheal wall movement can affect the lateral wall pressure and seal of an endotracheal cuff. This paper studies the relationship between proximal airway pressure (Paw) and the pressure in high-volume, low-pressure, tracheal tube cuffs. Cuff pressure changes during intermittent mandatory ventilation and continuous positive airway pressure (CPAP) cannot be explained solely by the effect of tracheal pressure, as reflected by Paw, on the annulus of the cuff exposed in the trachea. Cuff pressure showed wide swings and decreased below atmospheric pressure in the presence of small Paw fluctuations during CPAP breathing. Thus, adequate gas flow in the ventilator circuit cannot assure minimal pleural pressure changes. Decreases in cuff pressure may indicate inadequate CPAP and may explain why "just seal" pressure in endotracheal cuffs may not always prevent aspiration.