CPAP: Continuous positive airway pressure. CPAP is an effective treatment for obstructive sleep apnea. CPAP patients during sleep wear a face mask connected to a pump that forces air into the nasal passages at pressures high enough to overcome obstructions in the airway and stimulate normal breathing. The airway pressure delivered into the upper ai... Found on http://www.medterms.com/script/main/art.asp?articlekey=31372