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Diaphragmatic function after intense exercise in congestive heart failure patients
T J Kufel1, L A Pineda, R G Junega
1Division of Pulmonary and Critical Care Medicine, Veterans Administration Western New York Healthcare System, Dept of Medicine, State University of New York at Buffalo School of Medicine and Biomedical Sciences, Buffalo, NY, USA. thomas.kufel@med.va.gov
The European Respiratory Journal
|December 31, 2002
Summary
Diaphragmatic fatigue is uncommon in heart failure patients after intense exercise. This suggests that respiratory muscle weakness, not diaphragm fatigue, likely limits daily activities for these individuals.
Area of Science:
- Cardiology
- Respiratory Physiology
- Exercise Science
Background:
- Congestive heart failure (CHF) patients exhibit reduced respiratory muscle strength and endurance.
- This weakness increases susceptibility to diaphragmatic fatigue during physical exertion.
Purpose of the Study:
- To investigate the occurrence of diaphragmatic contractile fatigue in CHF patients post-intense exercise.
- To determine if diaphragmatic fatigue contributes to exercise limitation in heart failure.
Main Methods:
- Measured twitch transdiaphragmatic pressures (twitch Ptdi) using cervical magnetic stimulation (CMS) before and after exercise.
- Assessed unpotentiated and potentiated CMS responses in ten CHF patients (ejection fraction 31.2+/-9.8%).
- Patients performed a symptom-limited cycle exercise test at 60% of peak work capacity.
Main Results:
- Baseline twitch Ptdi: 15.9+/-6.3 cmH2O (unpotentiated), 28.8+/-10.7 cmH2O (potentiated).
- Post-exercise twitch Ptdi (10 min): 16.4+/-4.7 cmH2O (unpotentiated), 27.6+/-10.1 cmH2O (potentiated).
- Only one patient showed a significant fall (>15%) in twitch Ptdi, suggesting diaphragmatic fatigue.
Conclusions:
- Contractile diaphragmatic fatigue is infrequent in untrained CHF patients after high-intensity exercise.
- Diaphragmatic fatigue is unlikely to be the primary cause of exercise limitation in daily living for heart failure patients.