Abstract
BACKGROUND: Although sleep apnea has recently become a concern in patients with congestive heart failure (CHF), some patients with CHF exhibit characteristic oscillatory ventilation (OV) even when they are awake. We investigated the clinical significance of OV in patients with CHF, and effects of open-heart surgery on the OV. HYPOTHESIS: OV is an indicator of the severity of CHF, and this abnormal respiratory pattern improves with hemodynamic changes after open-heart surgery. METHODS: According to respiratory pattern in the cardiopulmonary exercise testing (CPX) before cardiac surgery, 50 patients with CHF were divided into 14 patients of OV-positive (OV+) and 36 patients of OV-negative (OV-). Then, the several indices of CPX before surgery, 1 week and 6 months after surgery were compared between the 2 groups. RESULTS: The peak VO2 before surgery was lower in OV+ patients than those in OV- patients (15.3 vs 18.8 m1/min/kg, p < 0.05). One week after surgery, anaerobic threshold (AT) and end-tidal C02 (ETC02) were lower in OV+ patients than those in OV- patients (AT: 9.5 vs 10,7 ml/min/kg, p < 0.05, ETCO2: 5.3 vs 5.6%, p < 0.05). However, 6 months after surgery, the statistical differences of these CPX parameters between the 2 groups were not found, and OV disappeared in 79% of OV+ patients. CONCLUSIONS: These data suggest that OV is an indicator of the severity of CHF, and gradually improved with the open-heart surgery.