Análise da força muscular respiratória e sua correlação com capacidade funcional em pacientes com insuficiência cardíaca crônica

Abstract

The systemic impairment of chronic heart failure (CHF) can cause changes in respiratory muscle strength with a possible relationship with the decline in functional capacity. Objectives: To evaluate and correlate respiratory muscle strength and functional capacity in patients with CHF. Material and methods: This an analytical cross-sectional study, involving patients diagnosed with compensated CHF, of both genders and aged ≥18 years. The measurement of respiratory muscle strength was performed using manovacuometry (maximum inspiratory pressure -PImax and maximum expiratory pressure -PEmax). To assess functional capacity, patients were randomized into groups: six-minute walk test (6MWT) or incremental shuttle walk test (ISWT). Data were analyzed using the Statistica 10.0 program, considering a significance level of 5%. Results: Forty-eight patients (67.8% men) with a mean age of 62.3 (58.0-66.6) years, ejection fraction (EF%) of 40.8 (37.8-43.7) were evaluated, with the majority (56.3%) functionally classified as NYHA II, which constituted the 6MWT (n=23) and ISWT (n=25) groups. Respiratory muscle weakness was not observed, with MIP above 70% of predicted [81.2 (74.7-87.8)] cmH2O and MEP [(95.6 (88.2-103.0)] cmH2O, however, the functional capacity was found to be reduced [6MWT= 416.0m (372.8-459.3) and ISWT= 304m (263.4-344.9)]. The values obtained for MIP and MEP showed a low correlation with the distance covered only from the ISWT (r=0.45; p=0.022 and r=0.41; p=0.041, respectively). Conclusion: Patients with CHF did not present respiratory muscle weakness and functional capacity was found to be reduced, with low positive correlation of the MIP and MEP obtained with the distance covered by the ISWT.