Central Oxygen Venous Saturation and Mortality in Patients Undergoing Coronary Artery Bypass Grafting

Abstract

Purpose: Central venous oxygen saturation (ScvO2) has been reported as a prognostic marker of in-hospital mortality when it is below 60% in certain situations. Nevertheless, it has not been widely reported in patients undergoing coronary artery bypass graft (CABG). The study determined the association between ScvO2 and in-hospital mortality in patients undergoing CABG in a high-complexity health institution in Santiago de Cali, Colombia. Patients and Methods: A retrospective cohort study was conducted with patients undergoing isolated CABG. The subject sample included 515 subjects aged 18 years or older. Exposure was defined as ScvO2 <60% upon admission to the intensive care unit (ICU) following surgery. The major outcome was mortality rates after 30 days. Furthermore, exposure variables were measured at preoperative, intra-operative, and postoperative time points. Results: A total of 103 exposed and 412 unexposed subjects were included. The final model revealed a higher mortality risk in individuals with ScvO2 <60% upon ICU admission compared with those with higher saturation levels (relative risk 4.2, 95% confidence interval: 2.4–7.2; p = 0.001). Values were adjusted using variables such as age (>75 years), low socioeconomic stratum, chronic kidney failure before surgery, unstable angina before surgery, ischemia time (>60 min), and intra-operative inotrope use. The primary cause of death was cardiogenic shock (54.7%), followed by sepsis (25.0%) and postoperative bleeding (17.2%). Conclusion: The study identified an association between ScvO2 <60% and in-hospital mortality in patients undergoing CABG.