Continuous monitoring of mixed venous oxygen saturation during aortic surgery.

The correlation between mixed venous oxygen saturation (SvO2) and hemodynamic measurements was studied in 13 patients undergoing descending thoracic aortic aneurysm resection (DTAAR). A significant correlation (p less than 0.05) was found between cardiac index (CI) and SvO2 after the induction of anesthesia and at the end of surgery. However, no significant correlation could be found between SvO2 and CI during the most critical periods of the surgery that included the collapse of the left lung, the aortic clamping, and the aortic declamping. During DTAAR, continuous SvO2 monitoring is useful, but it cannot substitute for intermittent cardiac output and oxygen consumption (VO2) determinations.