Short-term effect of air stacking and mechanical insufflation-exsufflation on lung function in patients with neuromuscular diseases

Air stacking (AS) and mechanical insufflation-exsufflation (MI-E) aim to increase cough efficacy by augmenting inspiratory lung volumes in patients with neuromuscular diseases (NMDs). We studied the short-term effect of AS and MI-E on lung function. We prospectively included NMD patients familiar with daily AS or MI-E use. Studied outcomes were forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and peak expiratory flow (PEF) prior to, immediately after, and up to 2 h after treatment. Paired sample T-test and Wilcoxon signed-rank test was used. Sixty-seven patients participated. We observed increased FVC and FEV1 immediately after AS with a mean difference of respectively 0.090 L (95% CI 0.045; 0.135, p < .001) and 0.073 L (95% CI 0.017; 0.128, p = .012). Increased FVC immediately after MI-E (mean difference 0.059 L (95% CI 0.010; 0.109, p = .021) persisted 1 hour (mean difference 0.079 L (95% CI 0.034; 0.125, p = .003). The effect of treatment was more pronounced in patients diagnosed with Spinal Muscular Atrophy, compared to patients with Duchenne muscular dystrophy. AS and MI-E improved FVC immediately after treatment, which persisted 1 h after MI-E. There is insufficient evidence that short-lasting increases in FVC would explain the possible beneficial effect of AS and MI-E.