Is there a role for airway clearance techniques in chronic obstructive pulmonary disease?

Chronic cough and sputum production are common features of chronic obstructive pulmonary disease (COPD) and have a significant impact on exacerbation frequency and quality of life. Despite this, techniques to assist with removal of sputum from the airway do not have a well-defined role in COPD management. Clinical trials of airway clearance techniques (ACTs) in COPD have shown mixed results with little evidence of long-term benefit. However many studies have failed to account for the heterogeneity of COPD lung disease, particularly with regard to the presence of bronchiectasis. Analysis of short-term studies suggests that there may be a cohort of patients who will benefit from prescription of a sputum clearance regimen. This review proposes a physiological rationale for the use of ACTs in COPD, taking into consideration the presence of bronchiectasis, the amount of sputum produced, the degree of airflow obstruction and the presence of decreased lung elastic recoil. The selection of an optimal ACT for individuals with COPD should take into account its effects on lung vloumes, expiratory flow and dynamic airway compression. Care should be taken to avoid airway collapse during forced expirations in patients with reduced lung recoil pressure; positive expiratory pressure therapy or autogenic drainage may prove effective in this patient group. The acceptability of ACTs to patients should also be considered, especially where long-term adherence is required. Future research should focus on more appropriate matching of the physiological effects of individual ACTs to the pathophysiology of lung disease in COPD.