CPAP vs BiPAP: the difference and which you need
Last updated: 2026-10-28
Quick answer
CPAP delivers one constant air pressure that splints the airway open — the standard therapy for most obstructive sleep apnea. BiPAP delivers two pressures, higher on inhale and lower on exhale, for people who need breathing support or cannot tolerate CPAP. A doctor decides which, based on your diagnosis.
What CPAP does
CPAP (Continuous Positive Airway Pressure) blows a single steady pressure through a mask, holding the airway open so it cannot collapse. For the large majority of obstructive sleep apnea, CPAP — fixed or auto-adjusting — is the first-line and highly effective therapy.
What BiPAP does
BiPAP (Bilevel) provides a higher pressure when you breathe in and a lower one when you breathe out, which is easier to exhale against. It is used when higher pressures are needed, when there is a breathing (ventilatory) problem such as COPD or respiratory failure, or when someone cannot tolerate CPAP.
Which one do you need?
That is a medical decision. Most people with straightforward obstructive sleep apnea do well on CPAP; BiPAP is reserved for specific situations a physician identifies. Once a doctor has advised the therapy, you can rent the appropriate machine month to month or buy a ResMed CPAP or BiPAP outright — the ResMed AirSense 10 AutoSet for CPAP, the Lumis 100 VPAP ST where BiPAP ST is prescribed.
Related: read your report · try a machine on rent · buy a CPAP machine · what machines cost · starting CPAP
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