Background and Objective: Mixed venous oxygen saturation (SvO2) and mixed venous-to-arterial carbon dioxide difference (pCO2 gap) are indices of tissue perfusion that are used to detect early organ dysfunction. Several foreign studies have validated their use but there is still paucity of evidence in the local data. This study aims to determine the accuracy of SvO2 and pCO2 gap in predicting adverse outcomes in adult patients undergoing cardiac surgery.
Methods: This is a prospective cohort study which included 108 adult patients who underwent cardiac surgery from October 1 to December 20, 2016. SvO2 and pCO2 gap levels of subjects were taken on admission to the Surgical ICU and were analyzed as to their accuracy in predicting adverse outcomes namely organ dysfunction, in-hospital and 30-day mortality.
Results: The receiver operating characteristic (ROC) curves of SvO2 and pCO2 gap to predict organ dysfunction, in-hospital, and 30-day mortality were 0.43 and 0.64, 0.52 and 0.47, and 0.49 and 0.47, respectively. SvO2 and its combination with pCO2 gap revealed low sensitivity to predict adverse outcomes but showed good specificity. To predict organ dysfunction, SvO2 and its combination with pCO2 gap both have a specificity of 90%. To predict in-hospital mortality, they have a specificity of 82.93% and 85.37%, respectively. To predict 30-day mortality, they have a specificity of 84.44% and 86.67%, respectively.
Conclusion: SvO2 and its combination with pCO2 gap revealed good specificity in predicting adverse outcomes like organ dysfunction, in-hospital, and 30-day mortality.