Reference — Sleep Medicine
PAP Therapy Quick Reference
Side-by-side comparison of PAP modalities, mask interface selection, and a troubleshooting guide for common PAP-related problems — the essential lookup tables for sleep lab, home-care, and board exam scenarios.
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
Positive airway pressure (PAP) therapy is the primary treatment for obstructive sleep apnea (OSA) and is also used to support ventilation in hypoventilation syndromes and central apnea disorders. The correct modality depends on the patient’s apnea type, pressure requirements, and tolerance. All modes share the same core mechanism: pressurized airflow delivered via a mask interface that pneumatically splints the upper airway open throughout the respiratory cycle.
PAP Modalities
| Modality | Delivers | Typical Pressure | Primary Use |
|---|---|---|---|
| CPAP | One fixed pressure | 4–20 cm H₂O | Obstructive sleep apnea |
| APAP (auto-CPAP) | Auto-adjusts within a set range | 4–20 cm H₂O range | OSA when a single fixed pressure is hard to set; home auto-titration |
| BiPAP (S) | Separate IPAP + EPAP (spontaneous) | IPAP up to ~25–30 cm H₂O; EPAP ≥ 4 cm H₂O; IPAP−EPAP differential ≥ 4 cm H₂O | CPAP intolerance, high pressures, ventilation support |
| BiPAP-ST | Bilevel + backup rate | As above, plus a set backup rate | Hypoventilation, neuromuscular disease, central apnea |
| ASV | Variable pressure support + auto backup rate | Device-determined | Central / Cheyne-Stokes apnea — NOT in HFrEF with EF ≤ 45% |
ASV contraindication: Adaptive servo-ventilation is contraindicated in patients with heart failure with reduced ejection fraction (HFrEF) and EF ≤ 45% who have predominantly central sleep apnea. Evidence from the SERVE-HF trial showed increased cardiovascular mortality in this population.
Mask Interfaces
| Interface | Notes |
|---|---|
| Nasal mask | Most common; requires nasal breathing |
| Nasal pillows | Minimal facial contact; good for claustrophobia and lower pressures |
| Full-face (oronasal) | For mouth breathers, high pressures, or nasal obstruction |
| Total-face / oral | Selected cases |
Troubleshooting Common Problems
| Problem | Likely Cause | Fix |
|---|---|---|
| Mask leak | Poor fit/size, over-tightened straps | Refit, resize, readjust straps |
| Aerophagia (bloating) | Pressure too high; swallowing air | Lower pressure, add expiratory pressure relief, switch to bilevel |
| Nasal dryness / congestion | Inadequate humidity | Heated humidification, nasal saline or steroid |
| Pressure intolerance | High fixed pressure | Ramp, expiratory pressure relief, APAP, or bilevel |
| Skin breakdown | Mask-edge pressure | Refit, padding, alternate interface |
| Dry mouth | Mouth leak | Chin strap, full-face mask, humidification |
| Eye irritation | Leak directed toward eyes | Refit the upper mask seal |
| Residual events | Inadequate pressure or central apnea | Re-titrate; check for treatment-emergent central events |
Comfort & Adherence Features
Available comfort technologies
- ·Heated humidification — reduces nasal dryness, congestion, and mouth leak
- ·Ramp — gradually increases pressure from a low starting level at sleep onset to reduce initial discomfort
- ·Expiratory pressure relief (EPR / C-Flex) — lowers delivered pressure slightly during early exhalation
- ·Tubing temperature control — maintains heated humidity through the circuit to prevent condensation (rainout)
Medicare Adherence Requirement
Coverage standard: Use of ≥ 4 hours per night on ≥ 70% of nights over a consecutive 30-day period within the first 90 days of therapy, plus documented symptomatic benefit, is required for continued Medicare coverage of PAP equipment.
Clinical Notes
- CPAP provides no pressure support. It does not treat hypoventilation. When ventilation must be augmented — as in obesity hypoventilation syndrome, neuromuscular disease, or COPD overlap — bilevel (BiPAP-ST) is required.
- EPAP splints the airway open. The expiratory positive airway pressure component is what prevents upper-airway collapse; IPAP then adds inspiratory flow for ventilatory support. Never set EPAP below 4 cm H₂O, and maintain an IPAP−EPAP differential of at least 4 cm H₂O on bilevel modes.
- Use full-face mask for mouth breathers. A nasal mask with an open-mouth sleeper routes the pressurized airflow out through the mouth, generating significant leak and eliminating therapeutic pressure. A full-face (oronasal) mask or a chin strap with nasal interface resolves this.
- Mask fit is the single biggest adherence determinant. A well-fitted mask that seals without over-tightening — checked with the patient supine and at therapeutic pressure — reduces leaks, skin breakdown, aerophagia, and noise complaints simultaneously.
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.