Analysis of Pulmonary Mechanics and the Factors for Coughing in Duchenne Muscular Dystrophy

ABSTRACT

OBJECTIVE: To investigate the pathologic pulmonary mechanics and analyze the factors affecting cough ability in patients with Duchenne muscular dystrophy (DMD). METHOD: Thirty-one patients with DMD were investigated. The vital capacity (VC), maximum insufflation capacity (MIC), maximal inspiratory (MIP), and expiratory pressure (MEP) were measured. Unassisted peak cough flow (UPCF) and assisted PCF at three different conditions were evaluated. RESULTS: The mean value of MICs (1, 873 +/- 644 cc) was higher than that of VCs (1, 509 +/- 640 cc). MIP and MEP were 48.8 +/- 21.4% and 29.5 +/- 19.5% of predicted normal value respectively. MIP was correlated with UPCFs as well as MEP. All of three assisted cough methods showed significantly higher value than unassisted method (p<0.01). The manual assisted PCFs at MIC significantly exceeded those produced by manual assisted or PCFs at MIC. The positive correlation between the MIC-VC difference and PCF at MIC-UPCF difference was seen (p<0.01). CONCLUSION: Inspiratory muscle strength and the preservation of pulmonary compliance is important for the development of effective cough as well as expiratory muscle power. Thus, the clinical implication of the inspiratory phase in assisting a cough should be emphasized.