Therapies involving Positive Expiratory Pressure (PEP) are designed to keep the airways opened when the patient breathes out. There are a few different PEP devices, each having their own limitations and benefits. The way that PEP therapy works is that it keeps the lungs inflated with air. Basic science tells us that two things cannot occupy the same space. In people with cystic fibrosis, the mucus occupies precious space in the airways, preventing them from taking a full, deep breath.
PEP devices are either stand-alone, or can be used with a nebulizer. All PEP devices work by having a one way valve that creates resistance when the patient breathes out against it. With PEP therapy, the pressure difference that occurs when a patient breathes out allows the lungs to fill with additional air, which in turn will push the mucus out as the lungs try to return to an equilibrant volume.
In simpler terms, PEP therapy functions very similarly to trying to get mustard out of a squeeze bottle. If you were to just squeeze the bottle without shaking it, you would only get a puff of air, and that little bit of watery mustard (which I call a “musquirt”.) When you shake the bottle, you move the amount of air in the bottle to the bottom, which will force the mustard out when you squeeze.
PEP therapy is very effective when combined with postural drainage. However, the postural drainage positions, especially the ones in which a patient must lie face down, may make breathing against a PEP device too difficult. Some PEP therapies combine vibratory pressure, which helps loosen the mucus and dislodge it from the linings of the airways. The Flutter ®, Acapella ® and the Quake ® use a combination of vibrations and PEP to promote airway clearance.
Below are some pictures of different types of PEP therapy:
1) PEP mask
5) PEP attachment with nebulizer