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

Abstract

Objective: To consider the effect of active lung volume recruitment ("air stacking") on rate of decline in vital capacity. Design: Retrospective cross-sectional design. Patients: People with Duchenne muscular dystrophy. Methods: 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). Results: 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. Conclusion: 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.