Positive Expiratory Pressure (PEP)

Cystic fibrosis (CF) is a genetic condition caused by abnormalities in the function of the cystic fibrosis transmembrane regulator (CFTR) protein within the mucus-producing cells of the body. This dysfunction compromises the transport of water and charged ions across the cell membrane and results in the production of thick and sticky mucus.

The presence of sticky mucus in the airways can prevent the clearance of pathogens from the lungs and result in chronic respiratory obstruction. Removing this mucus is important to prevent infections in the airways, making it easier for CF patients to breathe.

Common airway clearance techniques

Chest physiotherapy is instrumental to clear mucus from clogged-up airways. Physiotherapists commonly use techniques that involve opening up the patient’s airways by focused breathing-in maneuvers, holding the air inside the lungs to create strong air pressure behind the mucus, and then expelling the mucus out of the lungs by forceful exhalation.

Airway clearance techniques frequently used by physiotherapists to relieve CF-related respiratory system symptoms include high-frequency chest wall oscillation, positive expiratory pressure (PEP), oscillating positive expiratory pressure (oscillating PEP), inhaled therapy, and oxygen therapy.

review has shown that PEP devices are more effective than other airway clearance approaches in reducing pulmonary flare-ups and are comparable for improving lung function and facilitating mucus drainage.

What is Positive Expiratory Pressure?

In this technique, the patient breathes in normally through a PEP mouthpiece and then exhales out forcefully against airway resistance created by the device. This generates a positive expiratory force that drives out mucus from the clogged-up airways.

Oscillating PEP is a variation of the PEP mouthpiece and works in a similar way, but it’s designed to generate vibrations as the patient exhales against resistance. The vibrations get transmitted along the airways, and aid in shaking and loosening up mucus.

How to use PEP devices

Many PEP devices are available, including Flutter, Acapella, AerobikA, and RC-Cornet. They usually come with pressure monitors and knobs that allow caregivers to set the desired level of resistance.

Multiple iterations of breathing-in and forced-exhalation maneuvers, followed by huff coughs, help in clearing out mucus.

For best results, patients need the right number of iterations and proper resistance on these devices, and to regularly clean the devices according to instructions to avoid inadvertent contact with airborne pathogens and allergens.

A physiotherapist or clinician can help decide the device that’s best for the patient, familiarizing them with the device, and defining the parameters that need to be set.


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