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BiPAP vs CPAP: what are the differences and when to choose each?
CPAP (continuous positive airway pressure) is the reference treatment for obstructive sleep apnea. But some patients require more sophisticated therapy: BiPAP (BiLevel Positive Airway Pressure), which operates with two distinct pressure levels. Understanding the difference between these two devices is essential for making the right therapeutic choice.
How does CPAP work?
A CPAP delivers a single constant pressure (or variable in the case of auto CPAP) during both inhalation and exhalation. This pressure keeps the upper airways open and prevents the collapses responsible for obstructive apneas. It is the first-line treatment for the vast majority of sleep apnea patients.
How does BiPAP work?
A BiPAP device delivers two different pressures:
- IPAP (Inspiratory Positive Airway Pressure): higher pressure during inhalation to keep airways open
- EPAP (Expiratory Positive Airway Pressure): lower pressure during exhalation to ease breathing out
The difference between IPAP and EPAP (called "pressure support" or PS) can be adjusted to match each patient's ventilation profile. Some BiPAPs include a backup breathing rate for patients whose spontaneous respiration is insufficient.
Comparison table: CPAP vs BiPAP
| Criterion | CPAP | BiPAP |
|---|---|---|
| Pressure levels | 1 level (EPAP = IPAP) | 2 levels: IPAP (inhale) + EPAP (exhale) |
| Exhalation comfort | Can be difficult at high pressure | Better thanks to reduced EPAP |
| Main indications | Obstructive apneas (OSA) | OSA with high pressure, central apneas, COPD, hypoventilation |
| Central apneas | Not treated | Yes (certain BiPAP-S/T or ASV models) |
| Medical prescription | Mandatory | Mandatory |
| Settings complexity | Simple | More complex (IPAP, EPAP, PS, backup rate) |
| Indicative price | €400 - €900 | €800 - €2,500+ |
| First-line for OSA | Yes | No (second resort) |
Who needs a BiPAP?
BiPAP is prescribed in specific situations where CPAP is insufficient or not tolerated:
- High CPAP pressure (above 14-15 cmH₂O): some patients find it hard to exhale against such high pressure. BiPAP reduces expiratory pressure, improving comfort and adherence.
- Central sleep apneas (CSA): unlike obstructive apneas, central apneas result from a failure of the brain's respiratory control. Certain BiPAP-ST or adaptive servo-ventilation (ASV) devices are indicated here.
- COPD (chronic obstructive pulmonary disease): COPD patients often experience nocturnal hypoventilation that benefits from BiPAP's inspiratory support.
- Obesity hypoventilation (Pickwick syndrome): severely overweight patients may hypoventilate at night, where BiPAP is more appropriate.
- Neuromuscular diseases: ALS, muscular dystrophy, advanced multiple sclerosis - BiPAP helps support failing respiration.
- CPAP intolerance at high pressure: when the patient can no longer tolerate exhaling against high pressure, BiPAP can be considered.
BiPAP subtypes for central apneas
- BiPAP-S (Spontaneous): triggered by the patient's spontaneous breathing - for patients who breathe on their own
- BiPAP-ST (Spontaneous-Timed): includes a backup rate if breathing stops - for patients at risk of central apneas
- BiPAP-ASV (Adaptive Servo-Ventilation): continuously adjusts pressures to treat complex central apneas, including Cheyne-Stokes syndrome
Who decides: CPAP or BiPAP?
Your pulmonologist or sleep specialist prescribes the appropriate device type based on your diagnosis. If you feel discomfort exhaling with your current CPAP, do not directly purchase a BiPAP without a consultation - your doctor may first explore other solutions (pressure reduction, EPR feature, adapted mask).
CPAP devices available at VivaRespire
Browse our auto CPAP and BiPAP / BiLevel categories.
Reimbursement and convention in Belgium
In Belgium, the RIZIV/INAMI convention provides access to a CPAP or BiPAP device on loan from an accredited centre - the patient never owns the device. VivaRespire offers direct purchase outside the convention, making you the owner of your equipment. For full details: CPAP reimbursement Belgium.
Frequently asked questions about BiPAP vs CPAP
CPAP delivers a single pressure during both inhalation and exhalation. BiPAP delivers two distinct pressures: higher pressure during inhalation (IPAP) and lower pressure during exhalation (EPAP). The gap between them, called pressure support, makes exhaling easier. BiPAP is more complex to set up and reserved for specific medical indications. For the majority of obstructive apnea patients, CPAP remains the reference treatment.
Several clinical reasons justify BiPAP. Either your optimal CPAP pressure is very high (above 14-15 cmH₂O) and exhalation becomes uncomfortable. Or you have central apneas, COPD, obesity hypoventilation syndrome or neuromuscular disease. Or your CPAP tolerance remains insufficient despite adjustments. Your pulmonologist decides based on your diagnosis and titration polysomnography.
BiPAP is indicated for patients with central apneas, severe COPD, obesity hypoventilation syndrome (Pickwick), neuromuscular pathologies (ALS, muscular dystrophy), or obstructive apneas requiring pressure above 14-15 cmH₂O. It is not a first-line treatment for simple obstructive apnea. If your CPAP works well, you do not need to switch to BiPAP.
Yes. A CPAP usually costs between €400 and €900, while a BiPAP device costs between €800 and €2,500 depending on the model and features (BiPAP-S, BiPAP-ST, ASV). The difference is explained by technical complexity: dual pressure valve, central apnea detection algorithms and optional backup rate. The extra cost is justified only when the medical indication requires it.
Yes, this is even a classic indication. If you can no longer tolerate your CPAP at high pressure, your doctor may consider switching to BiPAP. Before this change, several intermediate steps are possible: reducing the target pressure, activating the EPR (Expiratory Pressure Relief) function on your current CPAP, or changing your mask. Never purchase a BiPAP without prior medical advice.
The INAMI/RIZIV convention primarily covers CPAP and Auto-CPAP devices for obstructive sleep apnea. BiPAP falls under specific indications (central apneas, COPD, neuromuscular) which may be covered by other mechanisms (long-term home ventilation). Conditions differ and require prescription by an accredited centre. For more details: CPAP reimbursement Belgium.
The main manufacturers offering BiPAP in Belgium are ResMed (AirCurve range: S, ST, ASV), Philips Respironics (DreamStation BiPAP) and Löwenstein (Prisma25S and Prisma VENT). Each model differs by its algorithms, ergonomics and connectivity options. Model choice is a medical decision: your pulmonologist prescribes the device most suited to your clinical profile.