The authors retrospectively reviewed the charts of 36 pediatric patients who had undergone cardiac surgery with hypothermic cardiopulmonary bypass (CPB) (n = 24) or profound hypothermia with circulatory arrest (PHCA) (n = 12), none of whom had received dextrose in the clear CPB pump prime, maintenance iv fluids, or cardioplegia solution. The authors studied whether the doses of fentanyl or methylprednisolone, or rates of dextrose infusion from blood products during CPB or from vasoactive infusions in 5% dextrose in water, were correlated with the blood glucose concentrations at the termination of CPB. Because other investigations have indicated that even moderate hyperglycemia during cerebral hypoxia or ischemia may predispose patients to an increased risk of neurologic deficit, the authors wished to determine whether any of these factors might contribute significantly to the elevation in blood glucose commonly seen in these patients. Multiple regression analysis and ANOVA were performed on these data, and aPvalue of 0.0125 was considered significant. The dose of methylprednisolone, and rates of infusions of dextrose from blood products in the CPB pump prime or from 5% dextrose in water at the termination of CPB did not correlate significantly with the blood glucose level. The dose of fentanyl administered to patients prior to the end of CPB was significantly correlated with the glucose concentration (r2= 0.416;P= 0.0001). No patient who received ≥50 µg/kg of fentanyl had a blood glucose concentration of >200 mg/dl. This suggests that doses of fentanyl ≥ 50 µg/kg in conjunction with limiting exogenous dextrose infusion can attenuate the hyperglycemic response to hypothermic CPB and PHCA in children undergoing cardiac surgery.