Positive Expiratory Pressure

Positive expiratory pressure (PEP) therapy gets air into the lungs and behind the mucus using extra (collateral) airways.

2 min read
Jordan, an adult with CF, using a PEP device before huff coughing to clear mucus from her lungs.
Jordan, an adult with CF, using a PEP device before huff coughing to clear mucus from her lungs.

In positive expiratory pressure (PEP), a person breathes through a mask or a handheld mouthpiece. PEP devices allow air to flow freely as you breathe in, but not when you breathe out. You must breathe out harder against the resistance. It takes about four times as long to breathe out against the resistance than it does to breathe in. This helps air get behind the mucus and helps move it from lung and airway walls. It also holds your airways open, keeping them from closing.

Oscillating PEP

Oscillating PEP is an airway clearance technique (ACT), where the person blows all the way out many times through a device. Commonly known by their brand names (Flutter®, Acapella®, AerobikA®, and RC-Cornet®), these types of oscillating PEP devices work in two ways. First, they use resistance to make it more difficult to breathe out, like non-oscillating PEP devices. Oscillating PEP devices also create vibrations when you breathe out. The vibrations move mucus from the surface of your airways. After blowing through the device several times, the person huff coughs to clear the mucus from the lungs and out of the body.

Although your respiratory therapist may suggest a different way to use PEP based on your unique circumstances, typically, people perform 10 breaths before stopping to cough or huff cough mucus out of their airways. A typical session of PEP takes about 20 minutes to complete.


Reference to any specific product, process, or service does not necessarily constitute or imply its endorsement, recommendation, or favoring by the Cystic Fibrosis Foundation. The appearance of external hyperlinks does not constitute endorsement by the Cystic Fibrosis Foundation of the linked websites, or information, products, or services contained therein.

Information contained on this site does not cover all possible uses, actions, precautions, side effects, or interactions. This site is not intended as a substitute for treatment advice from a medical professional. Consult your doctor before making any changes to your treatment.

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