PEP & Oscillating PEP Devices

PEP and Oscillating PEP Devices

Positive expiratory pressure (PEP) devices and their oscillating cousins are simple handheld tools that make airway clearance more effective when mucus is tenacious or airways tend to collapse. They are adjuncts to — not replacements for — active breathing techniques such as ACBT.

How PEP works

Breathing out against a fixed resistance generates a back-pressure of roughly 10–20 cmH₂O. This splints the airways open during expiration, lets air get behind secretions through collateral channels, and prevents the early airway collapse that traps mucus in conditions such as COPD and bronchiectasis. The result is air behind the mucus and a more open path for it to travel out.¹

Oscillating PEP

Oscillating devices add a vibration to the back-pressure. The airflow oscillation (around 10–25 Hz) shears mucus off the airway wall and lowers its viscosity, while the PEP holds the airways open — a combination that is often more comfortable and more productive than PEP alone.²

For patients who genuinely cannot self-clear, high-frequency chest wall oscillation (the "Vest") is an option, but for most ambulatory adults a well-taught technique with a handheld PEP device outperforms bulkier equipment in real-world outcomes.

The main devices

The oscillating devices differ mainly in how they generate the vibration and whether they work in any position. Your physiotherapist matches the device to your airflow, dexterity and preference.

How a session runs

A typical session is several cycles of 10–15 breaths out through the device, each cycle finished with one or two huffs (the forced expiration technique) to clear the mobilised mucus, repeated for 10–20 minutes once or twice daily. Pairing the device with nebulised hypertonic saline beforehand increases its effect.

Cautions

PEP is avoided in untreated pneumothorax, after recent facial, oral or skull surgery, and with significant haemoptysis; it also needs a reasonable inspiratory volume to be effective. Devices should be cleaned and dried after every use.

Evidence and selection

PEP and oscillating PEP are recommended airway-clearance options in cystic fibrosis and bronchiectasis, with no single device shown to be clearly superior.^3,4 Choice is therefore guided by the airflow the patient can generate, comfort, portability and preference — and reviewed at each visit.

ACBT versus devices — what the evidence shows

Head-to-head trials and Cochrane reviews in both bronchiectasis and cystic fibrosis consistently find no single airway-clearance technique is reliably superior to another when each is taught well and done properly — ACBT, PEP and oscillating PEP produce broadly equivalent sputum clearance, lung function and quality of life over a treatment period.⁵ Differences between techniques in trials are small and inconsistent, whereas the difference made by how consistently a patient sticks with their technique is large and consistent — so adherence, not the choice of device, is the strongest predictor of results. Two practical nuances do emerge: adding postural drainage to ACBT can roughly double sputum cleared in a single session for those who tolerate positioning, and oscillating devices can have an edge when secretions are especially thick or tenacious. In short, the best technique is the one you will actually do every day, and many patients keep ACBT as an equipment-free fallback alongside a device.

The Vest — high-frequency chest wall oscillation (HFCWO)

The Vest is a system of high-frequency chest wall oscillation (HFCWO): an inflatable jacket, connected to an air-pulse generator, rapidly compresses and releases the chest wall many times per second (typically 5–20 Hz). These rapid oscillations are thought to loosen secretions and shear them from the airway walls, moving them toward the larger airways where they can be cleared with huffing or coughing. Because it is hands-free and works in any position, it can suit people who find self-directed techniques tiring or difficult — for example those with neuromuscular weakness, reduced dexterity, or difficulty sustaining a manual regimen. Sessions usually last 20–30 minutes, once or twice daily, and are combined with periodic huffing and, where prescribed, nebulised hypertonic saline. The evidence base is modest: systematic-review data in cystic fibrosis show HFCWO is broadly as effective as other airway-clearance techniques for lung function and secretion clearance, but it has not been shown to be superior, and it is substantially more expensive and less portable.⁶ Guidelines therefore position it as one option among several rather than a first-line choice, reserved mainly for patients in whom simpler, lower-cost techniques are unsuitable or have not worked. HFCWO is used considerably more widely in the United States than in the UK or Australia, where hand-held oscillating devices and active techniques such as ACBT are generally preferred as first-line. As with every technique, the most effective device is the one the patient will use consistently.

References & evidence base

1. Demchuk AM, Chatburn RL. Performance characteristics of positive expiratory pressure devices. Respir Care 2021;66(3):482–493.
2. Morrison L, Innes S. Oscillating devices for airway clearance in people with cystic fibrosis. Cochrane Database Syst Rev 2017;(5):CD006842.
3. Hill AT, Sullivan AL, Chalmers JD, et al. British Thoracic Society guideline for bronchiectasis in adults. Thorax 2019;74(Suppl 1):1–69.
4. McIlwaine M, Button B, Nevitt SJ. Positive expiratory pressure physiotherapy for airway clearance in people with cystic fibrosis. Cochrane Database Syst Rev 2019;(11):CD003147.
5. Lee AL, Burge AT, Holland AE. Positive expiratory pressure therapy versus other airway clearance techniques for bronchiectasis. Cochrane Database Syst Rev 2017;(9):CD011699.
6. Volsko TA. Airway clearance therapy: finding the evidence. Respir Care 2013;58(10):1669–1678.

References are numbered in citation order (Vancouver/BMJ style) and were current at the time of writing. Guidelines are living documents — verify against the latest version before clinical use.