Lung Volume Recruitment Slows Pulmonary Function Decline in Duchenne Muscular Dystrophy

Abstract

McKim DA, Katz SL, Barrowman N, Ni A, LeBlanc C. Lung volume recruitment slows pulmonary function decline in Duchenne muscular dystrophy. ObjectiveTo evaluate the long-term effect on measures of forced vital capacity (FVC) before and after the introduction of regular lung volume recruitment (LVR) maneuvers (breath-stacking) in individuals with Duchenne muscular dystrophy (DMD). DesignRetrospective cohort study of pulmonary function data, including FVC, cough peak flow (CPF), maximum inspiratory pressure (MIP), and maximum expiratory pressure (MEP). Data were collected for 33 months prior to and 45 months after LVR introduction. SettingAmbulatory care in a tertiary level regional rehabilitation center in Canada. ParticipantsAll individuals (N=22) with DMD (mean age ± SD, 19.6±2.4y), who were prescribed LVR and reported adherence with therapy. InterventionsIntroduction of regular LVR (breath-stacking); 3 to 5 maximal lung inflations (maximum insufflation capacity [MIC]) using a hand-held resuscitation bag and mouthpiece, twice daily. Main Outcome MeasuresMeasures included the rate of decline of FVC in percent-predicted, before and after the introduction of regular LVR. Changes in maximum pressures (MIP, MEP), MIC, and cough peak flows were also measured. ResultsAt LVR initiation, FVC was 21.8±16.9 percent-predicted, and cough peak flows were <270L/min (144.8±106.9L/min). Annual decline of FVC was 4.7 percent-predicted a year before LVR and 0.5 percent-predicted a year after LVR initiation. The difference, 4.2 percent-predicted a year (95% confidence interval, 3.5–4.9; P<.000), represents an 89% improvement in the annual rate of FVC decline. ConclusionsThe rate of FVC decline in DMD patients improves dramatically with initiation of regular LVR.