A mathematical model of differential tracheal tube cuff pressure: effects of diffusion and temperature.

The tracheal tube cuff performs an important function during anesthesia and critical care situations by allowing positive pressure ventilation and isolating the lungs from aspiration. Other maneuvers, such as pressure support ventilation and positive end-expiratory pressure, are also cuff-dependent. However, excessive cuff pressure, as well as long-term intubation without excessive cuff pressure, have been associated with significant morbidity and mortality. A straightforward mathematical model of differential tracheal tube cuff pressure has been developed. This model incorporates compliance, temperature variation, and net molar diffusion in determining differential tracheal tube cuff pressure. In addition, temperature and diffusion are modeled as separate processes which effect differential cuff pressure independently. Support for the validity of this model is based upon an analysis of existing data from prior studies.