What is the primary function of expiratory positive airway pressure (EPAP)?

The primary function of expiratory positive airway pressure (EPAP) is to maintain upper airway patency during expiration. EPAP works by providing a back pressure that keeps the airway open, preventing it from collapsing, especially during the expiration phase of breathing. This is particularly important in conditions like obstructive sleep apnea, where the airway may become obstructed during sleep due to the relaxation of the muscles in the throat.

Maintaining airway patency during expiration helps ensure that airflow is not hindered when breathing out, which can assist patients in achieving more effective ventilation and reducing the risk of apnea events. While some may confuse the role of EPAP with inspiratory functions, its key purpose lies in support during the expiratory phase.