A PEP device is a portable tool. It has a mouthpiece or mask and a valve for exhaling. It may have a dial or settings to adjust the pressure. A PEP device creates positive pressure in the airways when you breathe out. This means you have to push air out of your lungs harder, against pressure. This helps keep the airways open and allows air to get behind the mucus when you breathe in. Having air behind the mucus can help move the mucus up toward your mouth so that you can cough it out. Some devices also vibrate when you breathe out. This helps loosen mucus so you can cough it out.
Your doctor, nurse, or physical or respiratory therapist can show you how to use this device.