Background: Although nocturnal Cheyne-Stokes respiration alternating between hyperpnea and hypopnea has been considered a sign of severe heart failure, the clinical status of cardiac patients who exhibit oscillatory ventilation during wakefulness has not been clarified. This study was carried out to determine the relation between oscillatory ventilation during wakefulness and exercise capacity in patients with chronic heart disease. We also evaluated retrospectively whether the presence of oscillatory ventilation influences the long-term prognosis in these patients.
Methods: A total of 164 patients with left ventricular dysfunction performed a symptom-limited incremental exercise test. Respiratory gas exchange was measured on a breath-by-breath basis throughout the test. Oscillatory ventilation was defined when clear ventilatory oscillation of at least two consecutive cycles was identified at rest before exercise testing and the difference between the peak and nadir of oscillating ventilation was > 30% of the mean value of ventilation.
Results: Oscillatory ventilation was noted in 45 of 164 cardiac patients (27%), and the magnitude (mean ± SD) of oscillation in these patients was 45.5 ± 16.9%. Patients with oscillatory ventilation had significantly lower left ventricular ejection fraction than those without it (40.7 ± 12.7% vs 44.9 ± 11.6%, p < 0.05). However, parameters of exercise capacity such as the peak oxygen uptake (V̇o2), the slope of the increase in V̇o2 relative to the increase in work rate (ΔV̇o2/ΔWR), and the ratio of the increase in ventilation to the increase in carbon dioxide output (ΔV̇e/ΔV̇co2) were not significantly different between the two groups. The mortality rate during 1,797 ± 599 days of follow-up did not differ between the groups (p = 0.65).
Conclusions: Oscillatory ventilation present at rest before cardiopulmonary exercise testing is not significantly related to the peak V̇o2, ΔV̇o2/ΔWR, ΔV̇e/ΔV̇co2, or prognosis in patients with left ventricular dysfunction.