Positive Correlation Between Regional Cerebral Oxygen Saturation and Mixed Venous Oxygen Saturation During Off-Pump Coronary Artery Bypass Surgery.

BACKGROUND

The balance of oxygen delivery and consumption is essential in patients who are critically ill. Mixed venous oxygen saturation (Sv̄O2 ) is a standard method to evaluate oxygen delivery and consumption during anesthesia. However, Sv̄O2 is monitored through a pulmonary artery catheter, which is invasive. Regional cerebral oxygenation (rScO2) reflects oxygen saturation in a small region of the frontal lobes and is monitored noninvasively through near-infrared spectroscopy. In the present study, the correlation between rScO2 and Sv̄O2 was calculated during off-pump coronary artery bypass grafting surgery to determine whether a positive correlation exists between rScO2 and Sv̄O2 .

METHODS

A total of 56 subjects were consecutively enrolled in the study. Then rScO2 and Sv̄O2 were simultaneously monitored. The parameters were recorded at 5 time points: T1, 10 min after intubation (1.0 FIO2 for 10 min); T2, 20 min after intubation (0.60 FIO2 for 10 min); T3, at the end of the revascularization of the left anterior descending artery (0.60 FIO2 ); T4, after protamine infusion (0.60 FIO2 ); and T5, 10 min after protamine infusion (1.0 FIO2 for 10 min). The correlation between rScO2 and Sv̄O2 and the variation trend between rScO2 and Sv̄O2 when FIO2 increased from 0.60 to 1.0 were analyzed.

RESULTS

There was a significant positive correlation between rScO2 and Sv̄O2 at these 5 time points (r 2 = 0.77, 0.81, 0.70, 0.83, and 0.92, respectively). There also was a significant positive correlation between Δ rScO2 and Δ Sv̄O2 (n = 112, r 2 = 0.72, P < .001). Linear regression analysis revealed that Sv̄O2 had a positive correlation with rScO2 and cardiac output (r 2 = 0.68, P = .013).

CONCLUSIONS

There was a positive correlation between rScO2 and Sv̄O2 during off-pump coronary artery bypass grafting surgery, and there also was a positive correlation in the variation trend between rScO2 and Sv̄O2 .