Congestive Heart FailureLack of effect of increased inspired oxygen concentrations on maximal exercise capacity or ventilation in stable heart failure☆
Section snippets
Patient group
Seventeen men with New York Heart Association functional class II to III heart failure symptoms and severe left ventricular dysfunction (determined by a radionuclide ejection fraction <35%) were considered for this study. Patients were to be excluded if they experienced ventricular arrhythmias, hypotension, chest pain, ST-segment depression, or claudication during exercise testing, or if they were taking a β blocker. One patient was excluded during the practice exercise test because of chest
Baseline measurements
Patients did not have evidence of obstructive or restrictive pulmonary disease (Table I). Resting measurements of heart rate, mean arterial blood pressure, and arterial and venous lactate were not different between the 2 tests. During baseline exercise testing on room air, the average peak oxygen uptake was 14.5 ± 3.2 ml/min/kg, associated with a respiratory exchange ratio of 1.11 ± 0.07. Thirteen of the patients stopped exercise because of fatigue and 3 because of dyspnea. All patients had the
Discussion
In this double blind, randomized, controlled study, we failed to demonstrate any benefit in exercise performance with the administration of 60% oxygen to patients with chronic stable heart failure. Under conditions of normoxia (21%) and hyperoxia (60%), maximal exercise time, ventilation, and leg oxygen uptake were virtually identical.
There are several explanations for the failure of hyperoxia to be effective. First, the administration of 60% oxygen did not result in a significant change in
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Cited by (0)
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This study was supported by Claude D. Pepper-GRTC Grant AG-11268-04, National Institutes of Health, Bethesda, Maryland.