If you have severe obstructive sleep apnea, chances are good that your doctor has mentioned treatment with a positive airway pressure (PAP) machine. When they start tossing acronyms around, you may be totally confused. When it comes to CPAP vs BiPAP, there are four important differences to consider.

What is a CPAP machine?

When a person has obstructive sleep apnea, the muscles of their throat relax back and down, blocking the airway until their brain notices the lack of oxygen. Continuous positive airway pressure (CPAP) machines deliver air to the throat all night long, with a sustained flow of air, as a person sleeps.

CPAP machines use a mask that fits over the nose, over the mouth, or over both to deliver air.

What is a BIPAP machine?

Bi-level positive airway pressure (BIPAP) machines, on the other hand, perform the same function as a CPAP machine but with a varied level of air pressure on your inhale and exhale.

BiPAP machines use the same mask as CPAP machines.

CPAP vs BiPAP: What are the main differences?

CPAP and BiPAP machines have one common goal: to treat obstructive sleep apnea.

Among other considerations, there are differences in how they accomplish that goal and who they work best for.

How they work

CPAP machines are fairly straightforward. A mask is fitted over your nose, mouth, or both, and a constant stream of oxygen is delivered to the back of the throat to keep it open. You can program most CPAP machines to start the night with a mild pressure that increases towards optimal pressure after you fall asleep. A sleep titration study determines which pressure works best to keep your throat open all night.

BiPAP machines also keep the throat open with air, but with a significant difference. Whereas CPAP machines deliver a constant stream of air, BIPAP machines adjust their pressure to accommodate the inhale and exhale. BIPAP machines have dual pressure settings: ipap for the inhale, and epap for the exhale. The pressure drops slightly on the exhale so sleepers do not have to work as hard to exhale.

BiPAP machines also have a timer that can be set to measure regular breaths. When the breaths stop or there are too-long pauses between them, the machine increases the pressure to help the sleeper breathe.

Both machines may also come with a humidifier setting that can help reduce dryness in the mouth and throat (which goes a long way in protecting your oral health, too).

CPAP vs BiPAP machine indications

CPAP machines are the most prescribed type of PAP machine for sleep apnea, and with good reason. Many people with severe sleep apnea require constant pressurized air to keep their airway open. With adjustable pressure, CPAP machines can be a literal lifesaver.

However, some sleepers cannot tolerate the constant pressure on the back of their throat. They may feel as if they have to force their breath out, which can make them wake in the night. BiPAP machines ease the pressure so exhalation feels more natural.

Additionally, BiPAP machines may help when a patient also has chronic obstructive pulmonary disease (COPD). The lower pressure on the exhale can help sleepers with COPD better clear out the carbon dioxide in the lungs. Carbon dioxide is a waste product that pushes oxygen out of the bloodstream when it is not properly and completely exhaled. This is one of the reasons that those with sleep apnea wake with headaches in the morning.

Sleepers with congestive heart failure or coronary artery disease may also find more gentle relief with a BiPAP vs CPAP machine.

Finally, sleepers with central sleep apnea or complex sleep apnea may benefit from the timer feature on a BiPAP machine. These two more rare types of sleep apnea occur when the brain “forgets” to remind a sleeper to breathe. The timer functions as a reminder.


In terms of CPAP vs BIPAP cost, CPAP has traditionally been the cheaper option. BiPAP machines may be twice the cost of a CPAP machine, but this depends largely on the brand and all of the available features.

Insurance companies do generally pay at least a portion of both CPAP and BiPAP machines, but you may have a higher out-of-pocket cost with a BiPAP.


When it comes to maintenance and all of the parts of PAP machines, they are both pretty similar. Cleaning CPAP vs BiPAP machine follows the same general guidelines, including:

  • Cleaning once a week
  • Soaking mask, tubing, headgear, and plastic connections in warm, soapy water
  • Dusting the machine with a damp cloth
  • Clean filters (if present)
  • Dry thoroughly and check for air leaks once reassembled

Using distilled water in your PAP machine is also recommended, as is more frequent cleanings if you suffer from upper respiratory, illness, or allergy symptoms. Likewise, both types of machine should be cleaned if you notice mineralization or a musty smell or odor.

Which one is better for me?

Deciding on CPAP vs BiPAP depends a lot on comorbid conditions and what is most comfortable for you to use. The best PAP machine is the one that you will use every night as directed. That said, it is important to recognize that there will be an adjustment period, no matter which machine you choose.

The pressurized air may feel strange at first. If the pressure makes sleeping hard, talk to your doctor to see if they can adjust the pressure in the beginning.

The mask can also be adjusted. It should fit well but not too tightly. Try out different fits (and possibly different masks) until you find one that is comfortable. Cleaning the mask nightly can reduce irritation around the mask that occurs from trapped facial oils or bacteria.

Use earplugs if the sound of the machine is distracting. However, some sleepers find the sound of the PAP machine to be like white noise that actually helps them fall asleep.

When considering CPAP vs BiPAP, a sleep apnea dentist can help coordinate your care. AZ Dentist can help you on your way to a better night of sleep. Get in touch today!

Schedule Your Appointment