BiPAP vs. CPAP Machines: What are the Differences

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Raj Dasgupta, MD

CPAP and BiPAP are treatments for sleep apnea. CPAP is common and effective. It’s usually recommended first for obstructive sleep apnea. BiPAP might be used for severe cases or if you have other conditions like COPD. BiPAP and another treatment called ASV are for central sleep apnea, where the brain doesn’t signal the muscles to breathe.

This article explains CPAP and BiPAP, including how they work, when they’re used, and their costs.

What is CPAP?

A CPAP machine helps you breathe better while you sleep. It blows air into your airway, keeping it open. This prevents breathing pauses (apneas) common in sleep apnea.

The machine pushes air at a steady pressure, usually between 4 and 20 cm H2O. This constant pressure ensures your airway stays open so you can breathe properly.

CPAP machines come in different sizes. The most common one for home use is about the size of a shoebox. There are also smaller travel versions, some even as small as fitting in your hand. Travel models may have backup batteries for camping, and some are approved for use on planes by the FAA.

Some people find CPAP easy to adjust to, while others prefer BiPAP machines, which adjust pressure during inhales and exhales.

What is BiPAP?

BiPAP machines help with breathing by providing different air pressures for inhaling (breathing in) and exhaling (breathing out). The exhaling pressure (EPAP) is lighter than the inhaling pressure (IPAP), making breathing feel more natural. BiPAP machines typically have a pressure range of 4 to 30 cm H2O.

There are three settings for how the machine switches between IPAP and EPAP:

  1. Spontaneous: The machine senses your breathing and switches pressures as you naturally breathe in and out. Most people use this setting.
  2. Timed: You can program how long each inhaling and exhaling phase should last. It helps ensure you breathe a certain number of times per minute, similar to a ventilator.
  3. Spontaneous/timed: This setting mostly follows your natural breathing, but if you breathe too slowly, it switches to a timed mode to help.

BiPAP machines can also be either fixed or auto-adjusting:

  1. Fixed: The pressure settings stay the same all night.
  2. Auto-adjusting: The machine can change the pressure automatically based on how you’re breathing while you sleep.

What Is the Difference Between CPAP and BiPAP Machines?

BiPAP vs. CPAP Machines

CPAP and BiPAP machines are both used to help with breathing while sleeping. They push air into your airway to keep it open. Here’s how they’re different:

  1. Pressure Settings:

    • CPAP: It has one pressure setting, usually between 4 to 20 cm H2O. This pressure stays the same whether you breathe in or out.
    • BiPAP: It has two settings – IPAP for inhaling and EPAP for exhaling. This allows for lower pressure when you breathe out. The pressure range is typically from 4 to 30 cm H2O.
  2. Usage:

    • CPAP: Mainly used for obstructive sleep apnea (OSA).
    • BiPAP: Primarily used for central sleep apnea (CSA), and for certain heart, lung, and neurological conditions.
  3. Cost and Design:

    • CPAP: There are portable options for travel. Generally less expensive.
    • BiPAP: Designed for home use, often more costly due to additional features and settings.
  4. Insurance Coverage:

    • CPAP: Usually covered for OSA. BiPAP may be covered if CPAP isn’t suitable or effective.
    • BiPAP: Insurance may require proof that CPAP didn’t work before covering BiPAP.

Both types come with accessories like data collection features and climate control options (e.g., humidifiers, heated tubing).

When should you use BiPAP instead of CPAP?

If you have Central Sleep Apnea (CSA), Complex Sleep Apnea (CompSA), or Obesity Hypoventilation Syndrome (OHS), BiPAP might be recommended by your doctor. These conditions can make it hard to breathe normally during sleep, and BiPAP provides extra support compared to CPAP.

BiPAP is also helpful if you need high-pressure airflow. CPAP machines usually max out at 20 cm of H2O pressure, but BiPAP can go up to 25 cm of H2O, making it easier to exhale.

If you have COPD/Overlap Syndrome, where you have both sleep apnea and COPD, BiPAP can help balance oxygen and carbon dioxide levels in your bloodstream.

Additionally, if you can’t tolerate CPAP or need increased ventilation due to lung disease or another condition, BiPAP might be a better fit for you. However, keep in mind that BiPAP is often more expensive than CPAP, so insurance coverage may require documentation of your CPAP intolerance.

For mild cases of sleep apnea, you can consider using some anti-snoring devices or anti-snoring mouthpieces.

Benefits of BiPAP Therapy Compared to CPAP Therapy

Let’s talk about why using a BiPAP machine for sleep apnea can be better than a CPAP machine:

  1. Helps with Oxygen and Carbon Dioxide Levels: BiPAP helps keep your oxygen and carbon dioxide levels in check, which is especially helpful if you have a lung condition.

  2. Easier to Breathe Out: With BiPAP, breathing out is much easier, even when the airflow is strong. This makes it easier to get used to compared to CPAP.

  3. Less Chance of Swallowing Air: CPAP machines can sometimes make you swallow air, causing discomfort. BiPAP machines are less likely to do this since exhaling is easier.

  4. Maintains Normal Breathing: Some BiPAP machines let you set your preferred breathing pattern. This can help keep your breathing normal, even if you have conditions like Central Sleep Apnea.

  5. Treats a Variety of Conditions: BiPAP can treat many breathing issues, so if your condition changes, you don’t have to switch machines.

Downsides of BiPAP Therapy Compared to CPAP Therapy

Here are a couple of downsides to using a BiPAP machine instead of a CPAP:

  1. Higher Cost: BiPAP machines are more expensive than CPAP machines. On average, they can cost two to four times as much. Even if you have insurance coverage, it might be harder to get it for a BiPAP because CPAP is cheaper and more common.

  2. Adjustment Period: Just like with a CPAP machine, it can take some time to get used to sleeping with a BiPAP. While the mask and tubing might feel familiar, people who need very high pressure settings might still find it challenging to adjust.


1. What’s Similar Between CPAP and BiPAP?

Both CPAP and BiPAP are types of respiratory support. They use Positive Airway Pressure Therapy to send pressurized air into your airway, treating sleep apnea and other breathing issues.

2. Why Are BiPAP Machines Pricier?

BiPAP machines cost more because they’re more complex with extra parts and features compared to CPAP machines.

3. Are CPAP and BiPAP Masks Alike?

Most CPAP masks work with BiPAP machines, but for higher air pressure prescriptions, you might need a special mask that can handle it.

Need professional help to diagnose and address your sleep problems? Schedule an online consultation with sleep specialist Dr. Owen Napleton.

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