Positive Correlation Between Regional Cerebral Oxygen Saturation and Mixed Venous Oxygen Saturation During Off-Pump...

The balance of oxygen delivery and consumption is essential in patients who are critically ill. Mixed venous oxygen saturation (S_v̄O ) is a standard method to evaluate oxygen delivery and consumption during anesthesia. However, S_v̄O 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 S_v̄O was calculated during off-pump coronary artery bypass grafting surgery to determine whether a positive correlation exists between rScO₂ and S_v̄O .

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

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

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