How do CPAP and BiPAP differ?

• A. CPAP provides continuous airway pressure; BiPAP delivers two pressure levels (higher during inspiration, lower during expiration)
• B. CPAP provides two pressure levels; BiPAP provides a single constant pressure
• C. CPAP provides continuous airway pressure; BiPAP delivers two pressure levels (higher during inspiration, lower during expiration)
• D. CPAP delivers pressure support during expiration only

Answer: (C)

CPAP and BiPAP differ in how pressure is applied during breathing. CPAP delivers a single, continuous positive airway pressure throughout both inhalation and exhalation, mainly to keep the airway open. BiPAP provides two pressure levels—higher during inspiration to help pull air into the lungs and lower during expiration to ease exhalation. This dual-pressure setup reduces the work of breathing and can improve ventilation when more support is needed than a constant pressure provides. The other statements don’t fit because CPAP is not two pressures, BiPAP is not a single constant pressure, and CPAP isn’t limited to pressure support during expiration only.