Effect of inspiratory muscle training on functional capacity measured by dyspnea score in patients with chronic heart failure with reduced ejection fraction : a randomized controlled trial
Abstract:
Objective: To study the effect of moderate-intensity inspiratory muscle training (IMT) program on functional capacity, pulmonary function, inspiratory muscle strength, and the quality of life (QOL) in patients with chronic heart failure with reduced ejection fraction (HFrEF). Methods: We conducted a prospective randomized controlled, double-blinded study. Fourty patients with HFrEF (53±12 years, 83% male, LVEF of 26±8 %, NYHA II-III) were randomly 1:1 assigned to a 6-week daily program of IMT using the Threshold® IMT device at 40% of maximal inspiratory pressure (MIP) (IMT group, n=20) or to a placebo-IMT using loading at 15% of MIP (SHAM group, n=20). Dyspnea score, 6-minute walk test, maximal oxygen consumption, pulmonary function, inspiratory muscle strength (determined by MIP), and the QOL were assessed before and after the IMT. Results: A 6-week daily program of IMT significantly improved MIP, dyspnea and peak oxygen consumption. There was also a trend towards improvement in QOL score in the IMT group. Respiratory muscle strength (MIP 87.11 + 16.24 to 102.84 + 21.05 cmH2O, p 0.001), dyspnea (2.26 + 0.45 to 1.68 + 0.48, p 0.001) and peak oxygen consumption (17.4 + 5.04 to 19.22 + 4.56 ml/kg/min) were significant improved in IMT group and statistically significant improved compared with SHAM group. Conclusion: (1) Moderate-intensity inspiratory muscle training program in patients with HFrEF results in significant improvement in dyspnea, inspiratory muscle strength, and peak oxygen consumption as well as trend towards improvement in QOL. (2) Moderate-intensity IMT using threshold loading at 40 % of MIP was practically feasible to apply in NYHA II-III heart failure patients. (3) These findings suggest that IMT should be considered as a complimentary therapy in those patients with heart failure.