Association Between Intraoperative Hyperlactatemia and Infection After Cardiac Surgery With Cardiopulmonary Bypass: A Multicenter Retrospective Study

OBJECTIVES: To test the hypotheses that intraoperative hyperlactatemia is independently associated with increased postoperative infection risk in cardiac surgery with cardiopulmonary bypass (CPB). METHODS: This study involved 4970 cardiac surgical patients with CPB from two medical centers. Intraoperative hyperlactatemia was defined as blood lactate levels exceeding 2.0 mmol/L. The main objective was to investigate the association between intraoperative hyperlactatemia and postoperative infections. Furthermore, we identified the threshold values of intraoperative peak blood lactate levels linked to a heightened risk of postoperative infection. RESULTS: Postoperative infections occurred in 14.49% of the patients included in the study. Patients who developed postoperative infection had significantly higher intraoperative median peak lactate levels (3.5 mmol/L vs. 2.6 mmol/L and p < 0.001). After adjusting for confounders, patients with intraoperative hyperlactatemia had roughly a 1.5-fold increased risk of developing postoperative infection (adjusted OR: 1.49; 95% CI: 1.18-1.91; and p < 0.001). Moreover, the threshold for intraoperative peak blood lactate levels that correlated with a higher risk of composite in-hospital postoperative infection was approximately 2.7 mmol/L. CONCLUSIONS: Consistent with our hypothesis, intraoperative hyperlactatemia was independently associated with a 1.49-fold increased risk of postoperative infection in CPB-assisted cardiac surgery. Notably, maintaining intraoperative blood lactate levels below 2.7 mmol/L might lower the risk of such infections.