Types of PAP Machines: CPAP, APAP, BiPAP and ASV
Positive airway pressure (PAP) devices blow air through a mask to keep the airway open. They differ in how they deliver pressure. Your clinician prescribes the type and settings based on your sleep study and health conditions.
| Device | How it delivers pressure | Commonly used for |
|---|---|---|
| CPAP (continuous) | One fixed pressure all night | Obstructive sleep apnea; the standard first treatment |
| APAP (auto-adjusting) | Varies pressure within a set range, responding to detected events | Obstructive sleep apnea, including starting therapy without an in-lab titration in suitable adults |
| Bilevel PAP (BiPAP, BPAP) | Higher pressure when breathing in (IPAP) and lower when breathing out (EPAP) | People who cannot tolerate high CPAP pressures, and hypoventilation conditions |
| Bilevel with backup rate (BPAP ST) | Bilevel plus timed breaths if breathing slows or stops | Some central sleep apnea, neuromuscular disease, obesity hypoventilation and COPD with hypoventilation |
| Adaptive servo-ventilation (ASV) | Adjusts pressure support breath by breath to stabilize breathing | Central sleep apnea and complex or treatment emergent central apnea, in selected patients |
Notes
- ASV is not recommended for central sleep apnea in people with heart failure with reduced ejection fraction (ejection fraction 45 percent or less), after a large trial found higher cardiovascular death in that group.
- Comfort features such as ramp, expiratory pressure relief and humidification are available on most devices.
- Medicare has separate coverage criteria for bilevel and ASV devices.
Frequently asked questions
Is BiPAP better than CPAP?
Not in general. CPAP or APAP works for most people with obstructive sleep apnea. Bilevel is used when a person cannot tolerate CPAP or has a condition that needs extra breathing support.
Can I switch from CPAP to APAP myself?
Pressure settings and device type are prescription decisions. Ask your sleep clinician if your current setup is not working.
What does ASV do differently?
It tracks your breathing and adds or removes pressure support from breath to breath to smooth out the waxing and waning pattern of central apnea.
Sources
More reference tables
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