Effect of normothermic cardiopulmonary bypass on renal injury in pediatric cardiac surgery: A randomized controlled trial

OBJECTIVE: Hypothermic cardiopulmonary bypass (CPB), although associated with a reduction in oxygen requirement, has a number of disadvantages including detrimental effects on enzymatic function, energy generation, and cellular integrity. Normothermic perfusion is potentially a more physiologic method to maintain the functional integrity of major organ systems. One of the aims of this trial was to compare the effect of normothermic and hypothermic CPB on renal injury in pediatric patients undergoing cardiac surgery. METHODS: Fifty-nine children (median age, 78 months; interquartile range, 39-130) undergoing corrective cardiac surgery were randomized to either hypothermic (28°C) or normothermic (35°C-37°C) CPB. Urinary albumin, retinal binding protein (RBP) and N-acetyl-β-glucosaminidase (NAG) were measured preoperatively, end of CPB, 4, and 24 hours postoperatively and were expressed as a ratio of urinary creatinine. Serum creatinine was measured preoperatively, end of CPB, and 24 and 48 hours postoperatively. Results are expressed as a difference in means (normotheric - hypothermic) or as a ratio of geometric means (normothermic/hypothermic). RESULTS: Baseline characteristics were similar in both groups. For these biochemical markers no significant interactions between treatment and postintervention time were found. Serum creatinine (-2.10; 95% confidence interval [CI], -6.51-2.31), RBP (ratio, 0.96; 95% CI, 0.65-1.41), and NAG (ratio, 0.86; 95% CI, 0.56-1.36) were similar in the 2 groups (P ≥ .34), but the urinary albumin was significantly lower in the normothermic group (ratio, 0.63; 95% CI, 0.42-0.95, P = .03). CONCLUSIONS: Normothermic CPB is associated with similar renal impairment to hypothermic CPB in children undergoing heart surgery.