Active lung volume recruitment to preserve vital capacity in Duchenne muscular dystrophy

To consider the effect of active lung volume recruitment ("air stacking") on rate of decline in vital capacity.

Retrospective cross-sectional design.

People with Duchenne muscular dystrophy.

Vital capacity was measured at every patient visit and then graphed. Air stacking using volume-preset ventilation or manual resuscitator bag was introduced to all patients after their vital capacity plateaued (reached a lifetime maximum).

For 151 consecutive patients with multi-year data, the 1-year rate of greatest decline in post-plateau vital capacity was 104 ml (8.8%)/year and occurred from age 20 to 21 years. For 53 patients with multi-visit data for whom air stacking was begun at the immediate post-plateau visit, the 1-year rate of greatest decline in vital capacity was 118 ml (8.5%) and occurred from age 20 to 21 years. Between annual visits, vital capacity and maximum insufflation capacity increased 26.4% and 43.3% of the time, respectively. The peak of maximal vital capacity decline occurred more than 5 years later than previously reported without air stacking.

For patients with Duchenne muscular dystrophy, active lung volume recruitment may help to preserve vital capacity. Effects on post-plateau vital capacity may be a useful outcome measure for therapeutic trials.