This treatment for sleep apnea
keeps the upper airway open by providing a flow of air delivered through a face mask worn while sleeping. The prescribed pressure alternates between two levels: one to breathe in (IPAP) and one to breathe out (EPAP). The air is pressurized by a small machine and delivered through plastic hosing to the mask.
Also Known As: BiPAP
The bilevel allows me to breathe out more comfortably.