Nasal expiratory positive airway pressure (Nasal EPAP) is a treatment for obstructive sleep apnea (OSA) and snoring.
Contemporary EPAP devices have two small valves that allow air to be drawn in through each nostril, but not exhaled; the valves are held in place by adhesive tabs on the outside of the nose
The mechanism by which EPAP may work is not clear; it may be that the resistance to nasal exhalation leads to a buildup in CO2 which in turn increases respiratory drive, or that resistance to exhalation generates pressure that forces the upper airway to open wider
In OSA it appears to be effective to reduce but not eliminate apnea for people with mild to moderate OSA (Apnea–hypopnea index < 30) and for people who cannot tolerate CPAP, but within those groups it is not clear why some respond and others do not, and the evidence consists of small clinical trials with follow-up no longer than one year.As of 2015 there was evidence from one small trial that it may be useful in children with OSA.It has shown evidence of reducing snoring as well