Patients performed airway clearance with each device once and at matched oscillation frequencies and pressures. Patients completed pulmonary function tests before and after each session, and rated the comfort of the two devices.
Outcome measures
Sputum wet and dry weight, FEV1, FVC, comfort of the 2 devices
Main results
Mean sputum wet and dry weight produced during sine waveform and triangular waveform HFCWO sessions did not differ (p = 0.11 and p = 0.2, respectively). Mean changes in FEV(1) and FVC following HFCWO therapy were also comparable (p = 0.21 and p = 0.56, respectively). However, there was a significant reduction in air trapping by residual volume/total lung capacity ratio following triangular waveform HFCWO (p = 0.01). In addition, in vitro cough transportability was 10.6% greater following therapy with the triangular waveform device (p = 0.05). Patients perceived the two devices as equally comfortable (p = 0.8).
Authors' conclusions
Single-session sputum production is comparable with sine and triangular waveform HFCWO devices. Longer term comparisons are needed to determine whether sustained use of the devices results in clinically important differences in outcomes.