Background: Airway clearance may be impaired in disorders associated with abnormal cough mechanics, altered mucus rheology, altered mucociliary clearance, or structural airway defects. A variety of interventions are used to enhance airway clearance with the goal of improving lung mechanics and gas exchange, and preventing atelectasis and infection.
Method: A formal systematic review of nonpharmacologic protussive therapies was performed and constitutes the basis for this section of the guideline. In addition, the articles reviewed were found using the same methodology but were not limited to those that focused only on cough as a symptom. The MEDLINE database was searched for this review and consisted of studies published in the English language between 1960 and April 2004. The search terms used were "chest physiotherapy," "forced expiratory technique," "positive expiratory pressure," "high frequency chest compression," "insufflation," and "exsufflation."
Results: In general, studies of nonpharmacologic methods of improving cough clearance are limited by methodological constraints, and most were conducted only in patients with cystic fibrosis. Chest physiotherapy, including postural drainage, chest wall percussion and vibration, and a forced expiration technique (called huffing), increase airway clearance as assessed by sputum characteristics (ie, volume, weight, and viscosity) and clearance of the radioaerosol from the lung, but the long-term efficacy of these techniques compared with unassisted cough alone is unknown. Other devices that allow patients to achieve the same benefits derived from chest physiotherapy without the assistance of a caregiver appear to be as effective as chest physiotherapy in increasing sputum production.
Conclusions: Some nonpharmacologic therapies are effective in increasing sputum production, but their long-term efficacy in improving outcomes compared with unassisted cough alone is unknown.