[Perioperative central venous oxygen saturation and its correlation with mortality during cardiac surgery: an observational prospective study].

BACKGROUND

Cardiac surgery can produce persistent deficit in the ratio of Oxygen Delivery (DO) to Oxygen Consumption (VO). Central venous oxygen Saturation (ScvO) is an accessible and indirect measure of DO/VO ratio.

OBJECTIVE

To monitor perioperative ScvO and assess its correlation with mortality during cardiac surgery.

METHODS

This prospective observational study evaluated 273 patients undergoing cardiac surgery. Blood gas samples were collected to measure ScvO at three time points: T0 (after anesthetic induction), T1 (end of surgery), and T2 (24 hours after surgery). The patients were divided into two groups (survivors and nonsurvivors). The following outcomes were analyzed: intrahospital mortality, length of Intensive Care Unit (ICU) and hospital stay (LOS), and variation in ScvO.

RESULTS

Of the 273 patients, 251 (92%) survived and 22 (8%) did not. There was a significant perioperative reduction of ScvO in both survivors (T0 = 78% ± 8.1%, T1 = 75.4% ± 7.5%, and T2 = 68.5% ± 9%;  <  0.001) and nonsurvivors (T0 = 74.4% ± 8.7%, T1 = 75.4% ± 7.7%, and T2 = 66.7% ± 13.1%; < 0.001). At T0, the percentage of patients with ScvO< 70% was greater in the nonsurvivor group (31.8% vs. 13.1%;  =  0.046) and the multiple logistic regression showed that ScvO is an independent risk factor associated with death, OR = 2.94 (95% CI 1.10−7.89) ( =  0.032). The length of ICU and LOS were 3.6 ± 3.1 and 7.4 ± 6.0 days respectively and was not significantly associated with ScvO.

CONCLUSIONS

Early intraoperative ScvO < 70% indicated a higher risk of death. A perioperative reduction of ScvO was observed in patients undergoing cardiac surgery, with high intraoperative and lower postoperative levels.