Effects of Air Stacking Maneuver on Cough Peak Flow and Chest Wall Compartmental Volumes of Subjects With Amyotrophic Lateral Sclerosis

Objectives: To assess the acute effects of air stacking on cough peak flow (CPF) and chest wall compartmental volumes of persons with amyotrophic lateral sclerosis (ALS) versus healthy subjects positioned at 45° body inclination.

Design: Cross-sectional study with a matched-pair design.

Setting: University hospital.

Participants: Persons (N=24) with ALS (n=12) and age-matched healthy subjects (n=12).

Main outcomes measures: CPF, chest wall compartmental inspiratory capacity, chest wall vital capacity, chest wall tidal volume and operational volumes, breathing pattern, and percentage of contribution of the compartments to the inspired volume were measured by optoelectronic plethysmography.

Results: Compared with healthy subjects, significantly lower CPF (P=.007), chest wall compartmental inspiratory capacity (P<.001), chest wall vital capacity (P<.001), and chest wall tidal volume (P<.001) were found in subjects with ALS. Immediately after air stacking, CPF (P<.001) and chest wall compartmental inspiratory capacity (P<.001) significantly increased in both groups, with values returning to basal only in healthy subjects. After air stacking, the abdominal compartment (P=.004) was determined to be responsible for the inspired volume in subjects with ALS. Significantly higher chest wall vital capacity (P=.05) was observed in subjects with ALS 5 minutes after air stacking, with the rib cage compartment (P=.049) being responsible for volume change. No differences were found in chest wall vital capacity and compartmental volumes of healthy subjects. Chest wall tidal volume (P<.001) significantly increased during the protocol in the healthy subjects, mainly because of end-inspiratory (P<.001) and abdominal volumes (P=.008). No significant differences were observed in percentage of contribution of the compartments to the inspired volume and end-expiratory volume of both groups. No significant differences were found in chest wall tidal volume, operational volume, and breathing pattern in persons with ALS.

Conclusions: Air stacking is effective in increasing CPF, chest wall compartmental inspiratory capacity, and chest wall vital capacity of persons with ALS with no hyperinflation. Differences in compartmental volume contributions are probably because of lung and chest wall physiological changes.