Pulmonary function and functional capacity cut-off point to establish sarcopenia and dynapenia in patients with COPD

OBJECTIVE: To establish a cut-off point for clinical and functional variables to determinate sarcopenia and dynapenia in COPD patients, and to analyze the impact of skeletal muscle dysfunction (SMD) on these variables. METHODS: Cross-sectional study, screened COPD patients for sarcopenia or dynapenia through low muscle mass and hand grip strength (HGS). Clinical variables: pulmonary function, respiratory muscle strength and functional capacity (FC). The precision of the variables in determining points of predictive cut-off for sarcopenia or dynapenia were performed using the Receiver Operating Characteristic curve and two-way analysis of variance. RESULTS: 20 COPD patients stratified for sarcopenia (n = 11) and dynapenia (n = 07). Sarcopenia group presented lower lean mass and lower maximal inspiratory pressure (MIP), decreased HGS, reduced FC (p<0.050). Dynapenia group presented reduced MIP, lower HGS and walked a shorter distance at Incremental shuttle walk test (ISWT) (p<0.050). We found cut-off points of forced expiratory volume in one second (FEV1), MIP and maximal expiratory pressure (MEP) and ISWT. It is possible to identify sarcopenia or dynapenia in these patients. We found the coexistence of the conditions (SMD effect) in COPD – reduction in the distance in the ISWT (p = 0.002) and %ISWT (p = 0.017). CONCLUSION: In moderate to very severe COPD patients the sarcopenia could be predicted by FEV(1) (%predicted) < 52, MIP < 73 cmH2O, MEP < 126 cmH2O and distance traveled of < 295 m in ISWT. Whereas dynapenia could be predicted by FEV(1) < 40%, MIP < 71 cmH2O, MEP < 110 cmH2O and distance of < 230 m traveled in ISWT.