CPAP vs. BiPAP vs. APAP: What’s the Difference?

Aug 11, 2023
Fact Checked
Compare the functions and uses of CPAP, BiPAP, and APAP machines to determine the best one for you.

Key Takeaways

There are many sleep apnea machines on the market, all with a variety of features and capabilities. Your doctor may prescribe one of three sleep apnea machines: continuous positive airway pressure (CPAP), bilevel positive airway pressure (BiPAP), or automatic positive airway pressure (APAP). Read on to learn more about CPAP machines and how they compare to BiPAP and APAP devices.

What’s the difference between CPAP, BiPAP, and APAP?

All three types of machines treat the symptoms of sleep apnea using pressurized air to keep airways open during sleep. The difference lies in how they deliver pressure into airways and their level of adjustability. An oxygen concentrator is also a completely different type of device, as it provides pure oxygen rather than pressurized air. These devices are available as portable oxygen concentrators and home oxygen concentrators in order to best fit each person’s needs. Deciding which type of device to use depends on each person’s specific needs, sleep habits, prescription, and budget or insurance coverage.

What is a CPAP machine?

CPAP machines provide a continuous flow of air that pushes into your upper airway and lungs through a mask or device on your nose, mouth, or both. This pressure helps hold your airway open, keeping it from narrowing or collapsing, which prevents effective breathing during sleep. [1]Pinto, V. Sharma, S. Continuous Positive Airway Pressure. National Institute of Health. July 25, 2022. Found on the internet at:

How are CPAP machines used?

CPAP machines are the most common devices used in positive airway pressure (PAP) therapy for sleep apnea treatment. They’re the most basic, generally the least expensive, and most often recommended by sleep specialists. Travel CPAP machines are also helpful for those who travel often. To begin CPAP therapy, you will need to do a sleep study in a sleep lab to determine the right pressure setting for your condition. This study and setting adjustment is called a “titration,” and is conducted by a sleep specialist—usually a physician or respiratory therapist.

When the right pressure is determined, your CPAP device will be set to that pressure constantly during sleep. The pressure introduced to your airway from the CPAP machine goes through the tube and mask, and stays constant whether you’re breathing in or out.

What is a BiPAP machine?

Like a CPAP machine, a BiPAP machine introduces positive pressure into your upper airway and lungs to keep your airway open and prevent it from narrowing or collapsing. You can set BiPAP machines to different pressures for inhalation (breathing in) and exhalation (breathing out). This added capability makes BiPAP machines more expensive than CPAP machines, which can only be set to one pressure.

How are BiPAP machines used?

With BiPAP machines, the pressure coming from the machine is higher when you inhale, and lower when you exhale. “This can make it easier to breathe out against the incoming air and can be particularly helpful for people with certain conditions,” said John Landry, licensed registered respiratory therapist and founder of Respiratory Therapy Zone.

A BiPAP device may be preferable for people who struggle with discomfort using CPAP, or people who have more complex sleep apnea and breathing patterns. In most cases, new PAP users will be prescribed CPAP first. If you aren’t able to sleep with a CPAP device, or if CPAP therapy isn’t adequately treating your condition, your doctor may try BiPAP instead. Keep in mind that your insurance may not cover a BiPAP machine until it is documented that a CPAP machine wasn’t suitable.

What is an APAP machine?

Again, these machines use positive airway pressure to maintain an open airway during sleep. While CPAP and BiPAP machines need to be set to specific pressures, APAP machines adjust automatically within a defined pressure range.

How are APAP machines used?

APAP machines offer greater flexibility than other devices by automatically adjusting as you breathe and responding to your specific needs and breathing patterns. “It uses an algorithm that detects airway closure and adjusts the pressure as needed,” said Landry. “This can be beneficial for people whose pressure needs vary throughout the night or at different stages of sleep.”

For example, APAP machines can detect snoring or breathing obstruction and automatically increase the pressure. Alternatively, if you move into a position that results in easier breathing, an APAP machine will detect the lowered resistance and reduce the pressure coming from the machine. APAP machine adjustments are only made within a range of pressures defined by your doctor and programmed by your APAP supplier.

APAP machines have allowed some people to skip the lab sleep study and conduct the titration process at home instead. This works because the APAP device will automatically adjust to changes in your breathing during sleep, and your doctor can access the transcript of adjustments that is recorded by the machine. This record can then be used to determine a prescription of pressure ranges for your APAP device.

Because of their advanced features, APAP machines are typically more expensive than CPAP machines. Due to the difference in price, many insurance plans may not offer coverage for an APAP machine if a CPAP machine is capable of treating your condition effectively. Insurance coverage will depend on your policy.

Which sleep apnea machine is right for you?

You may not get a choice in your sleep apnea machine as your doctor will prescribe pressure settings and specify whether you need CPAP, APAP, or BiPAP. Your prescription will be sent to a supplier, who will offer the machine that fits your needs and may be covered by your insurance. Even so, it is helpful to understand when a doctor might prescribe one machine instead of another.

Who should use a CPAP machine?

A CPAP machine is typically prescribed for:

Who should use an APAP machine?

You may be prescribed an APAP machine if:

Who should use a BiPAP machine?

BiPAP is generally used for more complex or advanced sleep apnea treatments. Some examples include:

Other ways to improve your sleep apnea

If you’ve been diagnosed with sleep apnea and have a prescription for CPAP therapy, it is important to continue therapy as prescribed. CPAP devices and treatments will not cure your sleep apnea, but there are other things you can do along with PAP therapy to improve your condition and overall health.

Lifestyle changes that may help sleep apnea

Changing some habits and behaviors can improve your health and therefore may have a positive impact on your sleep apnea. Activities like meditation may even help with sleep apnea. With your doctor’s approval, here are some changes to consider:

  1. Weight loss: Carrying excess weight can worsen the symptoms of sleep apnea.
  2. Increased exercise: Moving your body more frequently can enhance blood flow, increase lung strength and capacity, and improve your overall well-being.
  3. Quit smoking: Smoking takes a toll on your lungs, but also causes dryness and inflammation in the airway, which can make OSA symptoms worse.
  4. Stop or reduce alcohol consumption: Studies show that alcohol consumption may be associated with an increased risk of sleep apnea and related symptoms. [2]Simou, E. Britton, J., Leonardi-Bee, J. Alcohol and the risk of sleep apnea: a systematic review and meta-analysis. Sleep Medicine. February 2018. Found on the internet at:

Bottom line

If you’ve been diagnosed with sleep apnea and need a CPAP, APAP, or BiPAP machine, determining which one is best will be based on several factors. Your condition, sleeping habits, prescription, and doctor’s recommendation all help to determine what PAP device will be right for you. Each type of machine has unique functions and benefits that can reduce symptoms of sleep apnea and promote restful sleep.

Frequently asked questions

Neither machine is better than the other. CPAP and APAP machines both treat conditions like sleep apnea, but have different capabilities. APAP machines are different from CPAP machines because they automatically adjust the air pressure to your breathing.

APAP stands for automatic positive airway pressure. This means that the machine is capable of automatically adjusting the positive airway pressure in response to the user’s breathing.

Yes, CPAP devices can help with snoring. Snoring in sleep apnea is caused by the narrowing of airways during sleep, and CPAP works by using air pressure to keep airways open.

CPAP and BiPAP devices both work by sending positive air pressure into your airways through a tube and a mask, which covers your nose, mouth, or both. This air pressure holds your airways open, allowing steady breathing during sleep.

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  1. Vanessa L. Pinto and Sandeep Sharma. Continuous Positive Airway Pressure. National Institute of Health. Updated July 24, 2023. Found on the internet at:
  2. Simou, E., et al. Alcohol and the risk of sleep apnea: a systematic review and meta-analysis. Sleep Medicine. February 2018. Found on the internet at:
Ayla Girouard Headshot
Ayla Girouard Author
Ayla Girouard, LPN, is a licensed nurse and health writer. Her clinical nursing practice specializes in long-term care and rehabilitation of conditions that most often affect older adults. As a nurse, she has seen firsthand that health-related information and products are often complicated or misrepresented, and her goal as a health writer is always to offer readers uncomplicated and unbiased content.
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Elizabeth U. Lyda Medical Reviewer
Elizabeth Lyda, RRT, holds a bachelor of science degree from Empire State College and associate of science degree with a certificate in Respiratory Care from Mansfield State University, and has been a respiratory therapist since 1983. She was named Respiratory Therapist of the Year in 2007 from the University of Rochester and remains licensed in the state of New York.
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