CPAP Machines

Comparing CPAP, APAP & BiLevel/BiPAP Machines: Which PAP Therapy Is Right for You?

What All PAP Machines Do

All three types—Fixed Pressure CPAP, Auto-Adjusting (APAP), and BiLevel/BiPAP—use pressurised air to prevent airway collapse during sleep. They share core components like a blower, mask, tubing, and optional humidification. The differences lie in how pressure is delivered, how flexible the machine is, and what health or comfort needs are being met.

Fixed Pressure CPAP Machines

How They Work

• Delivers one constant, prescribed air pressure (set by a sleep specialist after a sleep study).

• The pressure stays the same throughout inhalation and exhalation, night after night.

Best For

• People with obstructive sleep apnea (OSA) whose pressure requirement is stable.

• Users who prefer simplicity and predictable treatment.

• Those with good tolerance of the fixed setting and without major fluctuations (in weight, congestion, sleeping position, or respiratory health).

Pros

• Lower cost compared to more complex machines.

• Simple to use and maintain.

• Fewer settings to adjust; dependable once correctly prescribed.

Cons

• Less flexible when circumstances change (e.g., nasal congestion, sleeping on back, weight gain).

• May feel uncomfortable during exhalation for some users if pressure is high.

• Adjustments in settings generally require another sleep study.

Auto Pressure (APAP) Machines

How They Work

• Continuously monitors breathing, airflow, snoring, and patterns like partial obstruction, then automatically adjusts pressure up or down to maintain optimal airway patency.

• Has a preset minimum and maximum pressure range.

Best For

• Individuals whose pressure requirements vary nightly (due to allergies, congestion, or changing sleep positions).

• Users who want more comfort and less “fixed-pressure discomfort.”

• Those starting PAP therapy and/or want flexibility without frequent sleep studies.

Pros

• More comfortable since pressure adapts to what your body actually needs in real time.

• Less risk of over-pressure when not needed, which can improve tolerance and adherence.

• Good option for travel or nights with unusual sleep conditions.

• Most can operate as a fixed pressure CPAP machine as well via changing settings in the clinician menu.

Cons

• Slighlty more expensive than their fixed CPAP models.

• Potentially a more complex device and more settings to understand.

• Potential for minor pressure fluctuations waking some sensitive sleepers.

• Not always needed in straightforward, stable cases of OSA.

BiLevel / BiPAP Machines

How They Work

• Designed to provide two levels of pressure: one higher pressure during inhalation (IPAP), another lower pressure during exhalation (EPAP).

• Some machines also include modes with a backup breathing rate (for central or mixed sleep apnea or for those with compromised respiratory mechanics).

Best For

• Patients who struggle with exhaling under constant pressure (especially if fixed CPAP feels too “harsh”).

• People with more complex respiratory conditions: COPD, obesity hypoventilation syndrome, neuromuscular disorders, or central sleep apnea.

• Under certain medical conditions for users who require higher pressures at inhale but need easier exhalation

Pros

• More comfortable breathing cycle (easier exhale).

• Greater flexibility for health conditions needing assisted ventilation support.

• Capable of handling higher pressures without discomfort on exhalation.

• Some models with auto-BiPAP or adjustable IPAP/EPAP offer hybrid options.

Cons

• Generally the most expensive of the PAP therapies.

• More complex setup; requires careful prescription and monitoring.

• More moving parts and settings means more potential for error or improper use.

• Usually bulkier; might be less travel-friendly.

Side-By-Side Comparison Table

How to Choose the Right One

• Start with a sleep study: Your health professional should determine pressure needs, severity, and any complicating conditions.

• Think about comfort: If fixed pressure feels uncomfortable, especially when exhaling, APAP or BiPAP might be better.

• Consider future changes: If you anticipate changes like weight gain, seasonal allergies, or shifts in sleep position, a more flexible device may save you adjustments later.

• Portability: If you travel frequently, weigh unit size, battery options, and whether BiPAP modes might limit travel convenience.

Summary

• Fixed Pressure CPAP: Reliable baseline therapy, great for most users with stable OSA needing a straightforward solution.

• APAP: Offers dynamic response to your changing breathing needs through the night. Enhances comfort, especially when fixed CPAP feels strict.

• BiLevel/BiPAP: Reserved for higher needs: conditions that require more ventilatory support, difficulty exhaling, or mixed/central sleep apnea. Prescription required.

At CPAP Club, we recommend discussing these options with your sleep health specialist. Choosing the right machine type can make all the difference in comfort, adherence, and the effectiveness of your sleep apnea treatment.