Inspiratory muscle training in patients with chronic heart failure awaiting cardiac transplantation: Results of a pilot clinical trial

Background and Purpose. Persons with chronic heart failure (HF) have poor ventilatory muscle strength, and this weakness is associated with dyspnea. The purpose of this study was to examine the effects of inspiratory muscle training (IMT) on ventilatory muscle strength and dyspnea in patients with chronic HF. Subjects. Fourteen patients (mean age [+/-SD]=52+/-8.5 years) with end-stage cardiomyopathy and chronic HF (mean left ventricular ejection fraction=23%+/-13% and New York Heart Association class=3.6+/-0.6) participated in the study. Methods. Inspiratory muscle training was performed at 20% of maximal inspiratory pressure (MIP) for 5 to 15 minutes, three times a day, for 8 weeks. Dyspnea was evaluated at rest: and during exercise. Results. Both MIP and maximal expiratory pressure (MEP) were greater after 2 weeks of IMT (51+/-21 to 63+/-23 cm H2O and 85+/-22 to 96+/-19 cm H2O, representing 24% and 13% improvement). Dyspnea scores at rest and during exercise decreased after 2 weeks (2.0+/-0.7 to 1.3+/-0.5 and 3.6+/-0.5 to 2.6+/-0.6, representing 29% and 28% improvement) and plateaued throughout the remainder of IMT. Baseline MEP was related to the percentage of change in MEP after IMT (r= -.72), and several measures of pulmonary function were related to the degree of improvement in dyspnea after IMT (r=-.57 to -.82) and in MIP after IMT (r=.71). Conclusion and Discussion. Improvements in MIP, MEP, and dyspnea were found after 2 weeks of IMT. Greater pulmonary function was associated with greater improvement in dyspnea and ventilatory muscle strength after IMT. These improvements may decrease the dependency and impairment associated with chronic HF.