Central Venous Oxygen Saturation as a Predictor of Postoperative Morbidity and Mortality in Patients Undergoing Cabg: A Prospective Observational Study

Background: Central venous oxygen saturation (ScvO₂) reflects the balance between systemic oxygen delivery and consumption and may detect occult hypoperfusion during coronary artery bypass grafting (CABG). However, prognostic thresholds remain insufficiently defined in Indian cohorts. Methods: In this prospective observational study, 100 adults undergoing elective CABG were evaluated at a tertiary cardiac center. ScvO₂ was measured intraoperatively and postoperatively and categorized as Low (<60%), Normal, or High. Concurrent lactate levels, ejection fraction (EF), and Mini-Mental State Examination (MMSE) scores were recorded. Associations with morbidity, mortality, and postoperative ICU utilization were assessed using chi-square testing and multinomial logistic regression. Results: Low ScvO₂ (<60%) was significantly associated with mortality (p = 0.001), postoperative EF reduction (p = 0.038), complications (p = 0.006), intra-aortic balloon pump requirement (p = 0.024), elevated lactate levels (p < 0.001), and increased postoperative care demands (p = 0.004). High lactate levels (OR 15.2, p = 0.002), postoperative complications (OR 7.0, p = 0.005), and mortality (OR ≈0.0004, p < 0.001) independently predicted low ScvO₂. Conclusion: ScvO₂ values below 60% independently predicted adverse perioperative outcomes after CABG and showed improved prognostic value when combined with lactate. ScvO₂ monitoring is a practical, cost-effective tool for perioperative risk stratification in resource-limited settings.