A Cochrane review [Abstract] 1 included 15 studies with a total of 475 subjects. There was no difference between conventional chest physiotherapy (CCPT) and other airway clearance techniques in terms of respiratory function measured by standard lung function tests. The other techniques comprised, e.g., positive expiratory pressure (PEP), airway oscillating devices (AOD), mechanical percussive devices (MP) and external high frequency chest compression devices (HFCC), and exercise therapy.
No overall group differences between CCPT or PEP were demonstrated in terms of FEV1, weighted mean difference (WMD) -0.08 (95% confidence interval (CI) -1.45 to 1.62); FVC, WMD 0.38 (95% CI -1.56 to 2.33); or FEF25-75%, WMD -0.44 (95% CI -3.38 to 2.50). Two studies demonstrated significant but divergent differences between CCPT and PEP. There were no overall group differences between CCPT or extra-pulmonary percussive therapies in terms of FEV1, WMD -1.76 (95% CI -4.67 to 1.16); FVC, WMD -1.42 (95% CI -5.17 to 2.33); or FEF25-75%, WMD 0.49 (95% CI -2.53 to 3.52). There was no overall mean difference between CCPT and airway oscillation devices in terms of FEV1, WMD 2.80 (95% CI -0.39 to 5.99); FVC, WMD 1.80 (95% CI -0.83 to 4.43); and FEF25-75%, WMD 6.00 (95% CI: 0.55 to 11.45).
Studies undertaken during acute exacerbations demonstrated relatively large gains in respiratory function irrespective of airway clearance technique. Longer-term studies demonstrated smaller improvements or deterioration over time. Ten studies reported individual preferences for technique, with participants tending to favour self-administered techniques. Heterogeneity in the measurement of preference precluded these data from meta-analysis.
Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment).
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