Serum lactate clearance as a predictor of outcome in infants' postcardiac surgery

Background and Aims: Prediction of postoperative outcomes by conventional hemodynamic parameters and risk scoring systems immediately after pediatric cardiac surgery has not been found to be reliable. Trends in serum lactate value over time or serum lactate clearance were found to give better estimate. The present study aimed to find out the effect of serum lactate clearance on mortality after pediatric cardiac surgery. Methods: Out of the 150 pediatric cardiac surgical procedures performed during the study period, 131 patients meeting inclusion criteria were enrolled in the present study. The study population was observed for lactate levels immediately postoperatively (T0) and then every 4 h for the first 24 h (T1-T6) and lactate clearance was calculated. Patient's outcomes in view of mortality, duration of mechanical ventilation, and length of intensive care unit (ICU) stay were observed. Results: In our study, mortality was 9.23%. Median inter quartile range with Hodges-Lehmann median difference (95% confidence interval) lactate values were higher among nonsurvivors and statistically significant at T0 = (6.14 [3.43,7.34] vs. 2.50 [1.87,3.59]; 2.53 [1.02, 4.33], P ≤ 0.0001), T1 = (3.10 [2.81, 5.16] vs. 2.30 [1.73, 3.61];0.95 [0.13, 1.73], P = 0.032), T2 = (3.49 [3.03, 5.40] vs. 2.39 [1.66, 3.38];1.32 [0.48, 2.27], P = 0.004), T3 = (3.82 [2.99, 5.54] vs. 2.20 [1.58, 3.45]; 1.46 [0.50, 2.45], P = 0.003), T4 = (4.86 [3.35, 5.44] vs. 2.09 [1.42, 3.47]; 2.02 [1.09, 3.13], P ≤ 0.0001), T5 = (4.36 [3.80, 6.27] vs. 2 [1.32, 3.26]; 2.29 [1.41, 3.25], P ≤ 0.0001), and T6 = (4.12 [3.69, 5.83] vs. 1.82 [1.31, 3.15]; 2.34 [1.15, 3.21], P ≤ 0.0001). Nonsurvivors were having decreasing trend of lactate clearance which was statistically nonsignificant. Mechanical ventilation was prolonged in nonsurvivors compared to survivor (135 [202] h vs. 30 [77] h; P = 0.002); however, there was no significant difference in ICU stay (P = 0.764). Conclusion: Poor lactate clearance and high lactate level were associated with high mortality. Serial lactate levels and decreasing trend of lactate clearance in the early postoperative period is a good predictor of postoperative outcome in pediatric cardiac surgery.