Blood lactate levels during cardiopulmonary bypass as indicator of outcome in pediatric cardiac surgery

Objectives: In pediatric cardiac surgery, high blood lactate levels during cardiopulmonary bypass (CPB) are associated with tissue hy-poperfusion and contribute to postoperative complications. Studies indicate that blood lactate level is proportional to tissue oxygen debt. The objective of this study was to evaluate the change in blood lactate levels and perioperative morbidity and mortality. Methods: We conducted a retrospective analysis of 81 pediatric patients who have undergone cardiac surgery with continuous monitoring of serial measurement of blood lactate in Integrated Cardiac Service Unit, Dr. Cipto Mangunkusumo Hospital, Jakarta. Arterial blood samples were taken before, during CPB, and on admission to the Intensive Care Unit (ICU) and every 6 hours afterward. Duration of CPB, hemodynamic parameters, inotrope dosage and perioperative outcome were documented. Results: The largest increment in lactate level. occurred during CPB and decreased on admission to the ICU. Patients who had complications exhibited higher lactate levels at all time points. Lactate levels were higher in the group with complications at the end of surgery (4.4 vs 2.7 mmol/l; p=0.000), immediately after ICU admission (2.9 vs 1.9 mmol/l; p=0.000), 6 hours (1.9 vs 1.4 mmol/l; p<0.003), and 12 hours after admission (4.6 vs 2.8 mmol/l; p=0.000). Increased lactate concentration was reliably associated with patient length of ICU stay, liver function parameter and anion gap. Logistic regression analysis revealed that peak blood lactate levels of 3.5 mmol/l or higher during CPB were strongly associated with postoperative mortality and morbidity. Conclusions: Hyperlactatemia occurs during CPB may become an early indicator/predictive index for postoperative morbidity and mortality in pediatric patients. This study generates the hypothesis that strategies aimed to preserve oxygen delivery during CPB may reduce the occurrence of elevated lactate levels.