Respiratory muscle endurance in patients with chronic heart failure - the effect of treatment

Background. Studies have previously shown impairment of respiratory muscle function in patients with chronic heart failure. The effect of therapeutic intervention on respiratory muscle function is largely unknown. The aim of this study was to investigate the effect of treatment on respiratory muscle endurance. Method. Twelve patients (9 males, 3 females) with heart failure, ejection fraction less than 35%,were studied. Respiratory muscle endurance, tested as repeated maximal inspiratory and expiratory pressures, were measured at baseline and after 6 months of treatment. Results were analysed with a paired t-test. Results. Inspiratory muscle endurance, expressed as % decline, 45.2% (23.2%) at baseline, improved significantly after 6 months of treatment to 24.8% (13.8%) (P < 0.0275), and expiratory muscle endurance, expressed as % decline, 34.8% (23.9%) at baseline, improved nonsignificantly after treatment to 25.8% (11.9%) (P > 0.1604). Conclusion. This study demonstrates a selective improvement of inspiratory but not expiratory muscle endurance after 6 months of treatment.