CPAP: Continuous positive airway pressure. ... Patients with obstructive sleep apnea treated with CPAP wear a face mask during sleep which is connected to a pump (CPAP machine) that forces air into the nasal passages at pressures high enough to overcome obstructions in the airway and stimulate normal breathing. It is Continuous positive airway pressure (CPAP) therapy is a common treatment for obstructive sleep apnea. A CPAP machine uses a hose and mask or nosepiece to deliver constant and steady air pressure.