Respiratory muscle function and oxygen kinetics during maximal exercise and the early recovery period in congestive heart failure

C. Kasiotis, S. Nanas, A. Prekates, G. Alexopoulos, N. Kuvelas, A. Samakovii, T. Kyprianou, E. Tsagalou, J. Terrovitis

Research output: Contribution to journalArticlepeer-review

Abstract

OBJECTIVE: Dyspnea and fatigue are the main symptoms which impose exercise limitations on patients with chronic heart failure (CHF). Several lines of evidence suggest that the respiratory muscles have an important role in this pathophysiological effect, and maximum inspiratory (PImax) and expiratory pressures (PEmax) are often reduced in these patients. The aim of this study was to explore the relationship between PImax, PEmax and maximum oxygen consumption (VO2max) as well as between exercise-induced reduction of PImax, PEmax and oxygen kinetics during the early recovery period. METHOD: Forty-six consecutive patients with CHF (NYHA I-III) underwent an incremental cardio-pulmonary exercise test (CPX) on a treadmill within 48 hours of clinical/hemodynamic assessment. Pulmonary function, diffusion capacity and cardiac index were measured before exercise and PImax/PEmax before and after exercise while oxygen kinetics were monitored during CPX and during the early recovery period after exercise. The best fit first degree slope of VO2 decline during early recovery was calculated using appropriate computer software. RESULTS: Patients with more than 10% reduction of PImax after CPX (13 out of 46) had a significantly lower VO2max (14.2 ± 2.7 vs 18.3 ± 5.6 mL/kg/min, P=0.016), lower anaerobic threshold (10.4 ± 2.5 vs 14.1 ± 4.3 mL/kg/min, P=0.009) as well as delayed recovery of oxygen consumption (VO2 slope; 0.364 ± 0.133 vs 0.537 ± 0.226, P=0.027). PImax (before) and PImax (after) exercise, were weakly correlated with VO2max (r=0.3, P=0.041 and r=0.36, P=0.014 respectively). CONCLUSIONS: Exercise-induced reduction of inspiratory muscle strength characterizes CHF patients with limited exercise capacity and delayed recovery of oxygen consumption. This provides new insight into the pathophysiological mechanisms of exercise-induced dyspnea.

Original languageEnglish
Pages (from-to)623-630
Number of pages8
JournalArchives of Hellenic Medicine
Volume14
Issue number6
Publication statusPublished - 1997

Keywords

  • Endurance of respiratory muscles
  • Heart failure
  • Oxygen consumption recovery

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