Chart — Sleep Medicine
CPAP vs BiPAP vs APAP
All three positive airway pressure (PAP) modalities keep the upper airway open by splinting it with pressurized gas. The key difference is that only BiPAP adds pressure support to augment ventilation, and only APAP auto-adjusts its pressure throughout the night. Use this chart to match the right PAP mode to the patient’s diagnosis and clinical needs.
Written by Apex Respiratory Editorial Team
Educational use only. This material supports respiratory therapy education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional protocols, or physician orders. Always follow facility policies and current provider orders, and verify calculations independently before clinical use.
Overview
CPAP (continuous positive airway pressure), APAP (auto-titrating PAP), and BiPAP (bilevel positive airway pressure) are the three primary home PAP modalities for sleep-disordered breathing. CPAP delivers one fixed pressure, making it the simplest and most-studied first-line therapy for moderate-to-severe obstructive sleep apnea (OSA). APAP varies its output automatically within a clinician-set range, which can be useful when a single optimal pressure has not yet been established. BiPAP cycles between a higher inspiratory pressure (IPAP) and a lower expiratory pressure (EPAP), providing pressure support that offloads the respiratory muscles — the only PAP mode that actively assists ventilation and can address CO₂ retention.
Feature Comparison
| Feature | CPAP | APAP | BiPAP |
|---|---|---|---|
| Pressure profile | One fixed pressure throughout the cycle | Auto-varies within a set range | Separate IPAP (higher) and EPAP (lower) |
| Pressure support? | None | None | Yes (IPAP − EPAP) |
| Typical pressures | 4–20 cm H₂O | 4–20 cm H₂O range | IPAP up to ~25–30 cm H₂O; EPAP ≥ 4 cm H₂O; differential ≥ 4 cm H₂O |
| Treats hypoventilation? | No | No | Yes |
| Backup rate option? | No | No | Yes (BiPAP-ST) |
| Primary indication | Obstructive sleep apnea (first-line, moderate–severe) | OSA with variable pressure needs / home auto-titration | CPAP intolerance, high pressures, or hypoventilation (OHS, neuromuscular, COPD–OSA overlap) |
| Common use case | First-line moderate–severe OSA | Undetermined single titration pressure | Persistent events at high CPAP, aerophagia, or CO₂ retention |
| Main limitation | No ventilatory assist; aerophagia at high pressure | Not for hypoventilation | More complex titration |
All three modalities keep the airway open with positive pressure; only BiPAP adds pressure support to augment ventilation, and only APAP auto-adjusts throughout the night. Pressure ranges are typical home PAP ranges for sleep-disordered breathing — not acute hospital NIV settings.
Related Resources
Sources
- Kacmarek RM, Stoller JK, Heuer AJ. Egan's Fundamentals of Respiratory Care. 12th ed. Elsevier; 2021.
- Patil SP, Ayappa IA, Caples SM, et al. Treatment of adult obstructive sleep apnea with positive airway pressure: an American Academy of Sleep Medicine clinical practice guideline. J Clin Sleep Med. 2019;15(2):335-343.
- Kushida CA, Chediak A, Berry RB, et al. Clinical guidelines for the manual titration of positive airway pressure in patients with obstructive sleep apnea. J Clin Sleep Med. 2008;4(2):157-171.