Common symptoms of chronic obstructive pulmonary disease, or COPD, include shortness of breath, a frequent cough or cough that produces a lot of mucus, wheezing, and tightness in the chest. Excess mucus production and poor airway mucociliary clearance can obstruct air passages, making it difficult to breath, reducing the effectiveness of inhaled medications, and trapping bacteria that can lead to frequent infections. High frequency chest wall oscillation (HFCWO) is an airway clearance technique that loosens mucus by applying vibrations at different frequencies to the chest wall via a wearable vest.
How does HFCWO work?
HFCWO devices typically consist of an inflatable vest, connected by hoses to an external generator, that delivers percussion to the chest wall. Rapid and repeating pulses of positive air pressure gently oscillate (squeeze and release) the chest to facilitate mucus clearance.
The therapy must be prescribed, and is typically used with a bronchodilator to enhance the opening of the airways. It is adapted for each person, starting with low pressures and frequencies that increase until a recommended pressure/frequency is reached. This treatment is usually given while the patient is seated an upright position, with sessions lasting about 30 minutes. Pauses are taken to cough out mucus that has loosened and moved into the large airways.
Many of these devices use air bladder technology (SmartVest, The Vest) with hoses connected to an external, programmable air pulse generator. Another, called AffloVest, is the first HFCWO vest with built-in oscillating modules and is battery-powered, allowing for greater mobility during therapy. Treatment can also be given regardless of whether a person is sitting, standing, or laying down.
Studies of HFCWO in COPD and other diseases
A few studies have evaluated HFCWO in terms of life quality in people with COPD. One (NCT00883616) was randomized and controlled crossover study that compared HFCWO treatment to self-administered breathing exercises in 22 COPD patients. Therapy was given in 20-minute sessions, twice daily, for four weeks, followed by a two-week washout period. Results showed that the treatment was well-tolerated and that mucus production declined during this treatment, easing symptoms and improving quality of life.
Another, a Phase 2 study (NCT00181285) — sponsored by Johns Hopkins University — evaluated HFCWO therapy in adults hospitalized due to asthma or COPD exacerbations. During four treatment periods, patients received either the HFCWO or a sham (fake device) treatment for 15 minutes, three times a day. Results of this study also showed that the treatment was well-tolerated in patients being treated for acute flares, and those given HFCWO demonstrated a clinically significant improvement in dyspnea (shortness of breath) after treatment compared to the control group.
HFCWO is mainly used to treat cystic fibrosis, a condition characterized by accumulation of thick mucus in the airways. Besides COPD, it is also prescribed for people with bronchiectasis, cerebral palsy, and muscular dystrophy.
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