CPAP versus BIPAP Therapy

One of the frequently asked questions about PAP (Positive Airway Pressure) therapy is what is the difference between CPAP and BIPAP?


CPAP Multi-Mask PillowCPAP – Continuous Positive Airway Pressure

CPAP(Continuous Positive Airway Pressure) has always been the gold standard for treating Obstructive Sleep Apnea. A CPAP machine delivers a specific set pressure with a continuous flow of air. This is delivered via a mask and hose and the air pressure works as a pneumatic splint in your airway to keep your airway open and your tongue pushed forward. The correct CPAP pressure is set after a proper titration of pressures during your sleep. The majority of patients with uncomplicated obstructive sleep apnea usually only require a CPAP machine. Most people will easily adapt to breathing out against the back pressure of the CPAP over the first few weeks of therapy. A small portion of people will have difficulty breathing out against the back pressure and will have trouble adapting to the therapy. All CPAP machines have a Ramp feature which allows the CPAP to start at lower than therapeutic pressures to allow patients to get to sleep breathing against less pressure, and as one falls asleep the pressure slowly increases to the therapeutic pressure. In the last few years special features such as AFLEX,CFLEX and EPR have been added to CPAP machines and they allow for a small pressure drop of up to 3 cm H2O during exhalation to make it easier to exhale.

CPAP BiPAPVPAP/BIPAP – Variable Positive Airway Pressure and Bi Level Positive Airway Pressure 

BIPAP and VPAP are both trademarked names for the same therapy. If you have a Philips Respironics machine it is BIPAP and if it is manufactured by Resmed it is a VPAP. BIPAP/VPAP machines are designed to deliver two differing pressures between inhalation and exhalation. The difference between the two pressures is usually 4 cm H2O or greater. During exhalation the BIPAP delivers a set pressure and then as the patient initiates a breath the machine will now deliver a higher pressure, as exhalation starts the machine pressure then drops again. BIPAP/VPAP is not necessary for most people with uncomplicated Obstructive Sleep Apnea. It is sometimes used for people who have a hard time adapting to CPAP, but this is not its main purpose, especially now with the EPR or CFLEX features on CPAP machines, which also allow for a small pressure drop on exhalation. BIPAP is traditionally used for patients with COPD, some cardiopulmonary disorders, certain neuromuscular disorders, and when higher pressures may be required as in morbidly obese patients. The best way to determine if you are a candidate for a BIPAP versus a CPAP is to speak to your Sleep Physician. Sometimes the only way to know for sure is a full sleep study at a local sleep lab.