Comparison of two mechanical insufflation-exsufflation devices in patients with amyotrophic lateral sclerosis: a preliminary study.

Background
Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease affecting upper and lower motor neurons and resulting in progressive skeletal muscle weakness. Weak cough and difficulty in clearing secretions are often the cause of pulmonary infections and acute respiratory failure. Cough assistance is commonly used to provide support in coughing for patients with ALS.

Methods
This was a preliminary parallel randomized study comparing two cough-assist devices: one utilizing mechanical insufflation/exsufflation (MI/E) and expiratory flow accelerator (EFA) technology, the other utilizing only MI/E technology. The aim was to compare the effectiveness, safety and acceptability of the two devices. Thirty patients with ALS and similar severity and functional scale were enrolled. The primary outcome was the change in respiratory function, respiratory muscle function, gas exchange, and peak cough expiratory flow as an indicator of cough efficacy. Secondary outcomes were the number of exacerbations at 1, 6 and 12 months of treatment, and the patient-perceived comfort/distress related to the interventions together with the perceived efficacy of cough.

Results
Thirty subjects were recruited and randomized into the two groups (1:1 ratio). Primary outcomes : respiratory function parameters decreased over time in both groups, but significantly less in the Kalos group, as did the respiratory muscle strength parameters and peak cough flows. Gas exchanges decreased over time in both groups with no clinically relevant differences between groups. Secondary outcomes : there were no significant differences between groups regarding the number of exacerbations over time. No adverse events were reported. All participants, in both groups, reported a similar increase in perceived cough efficacy and there was no significant difference in comfort and distress between the two treatments.

Conclusions
The cough-assist device with EFA technology performed better than a traditional MI/E device in ALS patients regarding respiratory function and cough efficacy, although number of exacerbations and acceptability of the two devices was similar. Following these promising preliminary results, further investigation is required in a larger cohort to confirm the superiority of EFA technology associated with a MI/E device.