Exhalation pressure relief
Exhalation pressure relief is a CPAP feature that lowers the pressure on a CPAP machine when the patient exhales in an effort to make breathing more comfortable. CPAP machines provide continuous positive airway pressure, making it easier for the patient to inhale, but harder to exhale. Exhalation pressure relief generally offers three possible settings: 1, 2 or 3, with each number signifying the number of cmH2O of pressure reduction. (A setting of 1 provides the least pressure relief; a setting of 3 provides the greatest relief).
There are several brand-specific terms for exhalation pressure relief. ResMed uses the term EPR. Philips-Respironics uses the term A-Flex for its APAP machines, Bi-Flex for its BiPAP machines, and C-Flex for its CPAP machines.