ABSTRACT
Background: Patients with chronic heart failure have a lower inspiratory muscle strength and fatigue endurance. Aim: To assess the effects of selective training of respiratory muscles in patients with heart failure. Patients and methods : Twenty patients with stable chronic heart failure, aged 58.3 ñ 3 years with an ejection fraction of 28 ñ 9 percent, were subjected to respiratory muscle training with threshold valves. The load was fixed in 30 percent of maximal inspiratory pressure (PImax) in 11 and in 10 percent of PImax in nine. Two sessions of 15 minutes, 6 days per week, during 6 weeks were done. Degree of dyspnea (Mahler score), maximal oxygen uptake, distance walked in 6 minutes, respiratory muscle function and left ventricular ejection fraction were measured before and after training. Results: Both training loads were associated to an improvement in dyspnea (+2.7 ñ 1.8 and +2.8 ñ 1.8 score points with 30 percent Plmax and 10 percent PImax respectively), maximal oxygen uptake (from 19 ñ 3 to 21.6 ñ 5 and from 16 ñ 5 to 18.6 ñ 7 ml/kg/min with 30 percent PImax and 10 percent PImax respectively, p< 0.05), PImax (from 78 ñ 22 to 99 ñ 22 and from 72 ñ 34 to 82.3 cm H20 with 30 percent Plmax and 10 percent PImax respectively), sustained PImax (from 63 ñ 18 to 90 ñ 22 and from 58 ñ 3 to 69 ñ 3 cm H20 with 30 percent PImax and 10 percent PImax respectively), and maximal sustained load (from 120 ñ 67 to 195 ñ 47 and from 139 ñ 120 to 192 ñ 154 g with 30 percent PImax and 10 percent PImax respectively). The distance walked in 6 min only increased in subjects trained at 30 percent PImax (from 451 ñ 78 to 486 ñ 68 m). Conclusions: Selective training of respiratory muscles results in a functional improvement of patients with chronic heart failure