CPAP is an airway treatment of using slight positive pressure during inhalation to increase the volume of inspired air and to decrease the work of breathing. Update Date: 09/12/2008Allen J. Blaivas, DO, Pulmonary, Critical Care, and Sleep Medicine, Department of Veteran Affairs, VA New Jersey Health Care System, East Orange , NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.