Chest Wall Oscillation for Asthma and COPD Exacerbations Trial (COAT)

Acute asthma and chronic obstructive pulmonary disease (COPD) are exceedingly common, which together account for nearly 1 million hospitalizations each year in the United States alone. Beta agonists, anticholinergics, and corticosteroids delivered in aerosolized forms (via respiratory inhalers or nebulization) are recommended in the treatment of acute asthma and COPD. These medications rely on deposition into distal airspaces to suppress airway inflammation or promote bronchodilation. Unfortunately, excessive mucous production and impaired airway mucociliary clearance can lead to airway plugging, and thereby reduce the deposition of and response to aerosolized medications. These considerations highlight the need for therapies that clear airways of mucus in the acute management of asthma and COPD. High frequency chest wall oscillation (HFCWO) creates high velocity, low amplitude oscillatory airflows when applied through a pneumatic vest worn over the thorax, and is used for airway mucus clearance in patients with cystic fibrosis, bronchiectasis, and neuromuscular disorders.

This was a randomized, multi-center, double-masked phase II clinical trial of active or sham treatment initiated within 24 hours of hospital admission for acute asthma or COPD at four academic medical centers. Patients received active or sham treatment for 15 minutes three times a day for four treatments. Medical management was standardized across groups. The primary outcomes were patient adherence to therapy after four treatments (minutes used/60 minutes prescribed) and satisfaction. Secondary outcomes included change in Borg dyspnea score (≥ 1 unit indicates a clinically significant change), spontaneously expectorated sputum volume, and forced expired volume in 1 second.

Inclusion criteria

• Age 18 years and older
• Admission to the inpatient medical service
• Physician-diagnosed asthma or asthma/COPD or COPD exacerbation.
• Evidence of airflow obstruction on spirometry

Exclusion criteria

• More than 24 hours since admission to the inpatient medical service
• Admission to an intensive care unit
• Hospital discharge planned within the next 24 hours
• Other chronic respiratory disease (e.g., sarcoidosis, idiopathic pulmonary fibrosis)
• Chest wall abnormalities (e.g., severe kyphoscoliosis) that precludes using the vest
• Chest wall or abdominal trauma/surgery in the past 6 weeks that precludes using the vest
• Physician declines to provide consent
• Patient unable (e.g., history of cognitive impairment, unable to understand English) or declines to provide consent
• Previous participant in this study
• Corticosteroid therapy (prednisone >0 mg/d equivalent) for >1 week prior to admission