Expiratory Positive Airway Pressure (EPAP)

Expiratory positive airway pressure (EPAP) is an emerging treatment for sleep apnea. Unlike continuous positive airway pressure (CPAP), EPAP does not require any bulky or noisy machinery. It also doesn't require batteries or electricity. Some healthcare professionals consider it preferable to CPAP because patients are more likely to use it consistently.

EPAP is a disposable one-way resister valve that is worn over the nostrils. It works similarly to CPAP but only provides minimal resistance on inhaling and positive pressure on exhaling. This opens the airway making it less likely to collapse and interfere with breathing.  

This article looks at the differences between EPAP and other sleep apnea treatments.

Man sleeping in his bed
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How EPAP Works

Apnea occurs during sleep when your airway collapses as you exhale. Because the airway does not automatically open back up, you temporarily stop breathing.

Positive airway pressure (PAP) is a treatment for sleep apnea. PAP devices work by sending pressurized air through your airway. This helps keep the airway open so you don't stop breathing.

EPAP stands for "expiratory positive airway pressure." This mode of breathing support only applies positive pressure when you are exhaling. This is based on the belief that airway collapse and sleep apnea are most likely to occur when you are breathing out.

One device that utilizes EPAP to treat sleep apnea is called Bongo RX. This technology is known as nasal EPAP. According to the manufacturer, the device has valves that open when you inhale and close when you exhale. The exhaled air generates pressure so your airway stays open. 

EPAP devices appear to be an acceptable alternative to CPAP for people with moderate or mild apnea, and one small study found that EPAP and CPAP were equally effective in people with moderate or severe apnea. Because they are smaller and less complicated than CPAP devices, people with apnea may also be more likely to use them consistently.

Differences Between EPAP, IPAP, CPAP, & BiPAP

CPAP is the most commonly prescribed treatment for sleep apnea. CPAP uses positive pressure constantly applied by a machine while you inhale and exhale.

BiPAP (bilevel positive pressure) is another type of PAP therapy. It also applies positive pressure while inhaling and exhaling, but not as a continuous pressure.

The difference between EPAP, CPAP, and BiPAP is that EPAP does not deliver positive pressure during inhalation. It only delivers positive pressure when you are exhaling.

IPAP stands for "inspiratory positive pressure." This technology delivers positive pressure only when you breathe in. Ventilators (life support machines for breathing) and BiPAP devices use both IPAP and EPAP technology.

Why Are PAP Machines Needed?

Sleep apnea affects about one-quarter of U.S. adults between the ages of 30 and 70. Most people who have sleep apnea are overweight. Other causes of sleep apnea include enlarged tonsils or adenoids. Sometimes these structures need to be surgically removed to cure sleep apnea.

People with untreated sleep apnea may experience a number of related health problems. These include:

  • Daytime sleepiness & fatigue
  • Impaired cognitive function
  • Metabolic dysfunction—your body doesn't break down or absorb nutrients normally
  • Heart disease
  • Depression or mood swings
  • Death

PAP machines help people with sleep apnea breathe normally. Studies have found that correct and consistent use of these devices over the long term improves daytime sleepiness and reduces cardiovascular problems including high blood pressure.


EPAP machines are similar to CPAP machines. Both devices deliver pressurized air to your airway while you sleep. An EPAP device, however, only delivers pressure when you exhale. This allows the device to be smaller and lighter. EPAP devices also do not require batteries or electricity.

EPAP devices may not work as well as CPAP devices, especially for people with more severe sleep apnea. Because they are simpler to use and less bulky than CPAP devices, however, people with mild to moderate sleep apnea may be more willing to use them consistently. 

Frequently Asked Questions

  • What is positive airway pressure?

    Positive airway pressure (PAP) is a treatment for sleep apnea. It uses pressure to keep the windpipe open during sleep. CPAP, EPAP, and BiPAP all work in slightly different ways to keep the airway open while you sleep. 

  • What is the difference between CPAP and EPAP?

    CPAP provides continuous positive airway pressure on both inhalation and exhalation. EPAP provides pressure on the exhale only. CPAP machines are typically bulky and require a power source, while EPAP devices do not.

  • Is EPAP as effective as CPAP?

    No, but it appears to be a suitable alternative for people with mild to moderate obstructive sleep apnea. While CPAP works better, patients have higher rates of compliance with EPAP because it is easier to use, compact, and does not require electricity.

  • What is APAP?

    Automatic positive airway pressure (APAP) is another device used to treat sleep apnea. During the night, an APAP machine automatically adjusts its pressure settings in response to a person's breathing.

  • What is a sleep apnea pillow?

    A sleep apnea pillow is a specially designed pillow made for people that use a CPAP device. Some designs have indentions for the CPAP hose to travel through while you sleep. Others may give more comfort when you're resting on your side. These can help prevent air leaks from your face mask.

12 Sources
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By Kristin Hayes, RN
Kristin Hayes, RN, is a registered nurse specializing in ear, nose, and throat disorders for both adults and children.