Lactate, endothelin, and central venous oxygen saturation as predictors of mortality in patients with Tetralogy of Fallot

BACKGROUND: Lactate and central venous oxygen saturation (ScVO(2)) are well known biomarkers for adequacy of tissue oxygenation. Endothelin, an inflammatory marker has been associated with patient's nutritional status and degree of cyanosis. The aim of this study was to explore the hypothesis that lactate, ScVO(2) and endothelin before induction may be predictive of mortality in pediatric cardiac surgery. METHODS: We conducted a prospective observational study of 150 pediatric (6 months to 12 years) patients who were posted for intracardiac repair for tetralogy of fallot and measured lactate, ScVO(2) and endothelin before induction (T(1)), 20 minutes after protamine administration (T(2)) and 24 hours after admission to ICU (T(3)). RESULTS: Preinduction lactate and endothelin levels were found to predict mortality in patients of tetralogy of fallot with an odds ratio of 6.020 (95% CI 2.111-17.168) and 1.292(95% CI 1.091-1.531) respectively. In the ROC curve analysis for lactate at T(1), the AUC was 0.713 (95% CI 0.526–0.899 P = 0.019). At the cutoff value of 1.750mmol/lt, the sensitivity and specificity for the prediction of mortality was 63.6% and 65.5%, respectively. For endothelin at T(1), the AUC was 0.699 (95% CI 0.516–0.883, P = 0.028) and the cutoff value was ≤2.50 (sensitivity, 63.6%; specificity, 58.3 %). ScVO(2) (odds ratio 0.85) at all three time intervals, suggested that improving ScVO(2) can lead to 15% reduction in mortality. CONCLUSIONS: Lactate, ScVO(2) and endothelin all showed association with mortality with lactate having the maximum prediction. Lactate was found to be an independent, reliable and cost-effective measure of prediction of mortality in patients with tetralogy of fallot.