BLOOD GLUCOSE LEVEL AND EARLY NEUROLOGIC RECOVERY AFTER CARDIAC SURGERY WITH CIRCULATORY ARREST IN INFANTS

Abstract

Introduction: While high blood glucose levels can exacerbate cerebral ischemic damage in the normothermic mature brain, the relationship between glucose levels and neurologic outcome following deep hypothermic circulatory arrest (DHCA) is unknown for the immature brain of neonates and infants. Methods: Indicators of perioperative neurologic dysfunction were compared with serial serum glucose measurements drawn during a prospective, randomized, single-center trial of 171 infants undergoing the arterial switch procedure for transposition of the great arteries (Boston Circulatory Arrest Study) [1]. Infants in this study were assigned to a bypass strategy of predominant circulatory arrest (CA, n=87) vs. predominant low-flow bypass (LF, n=84). Perfusion methods and anesthetic management were rigorously standardized for all patients. Serum glucose levels were measured after induction of anesthesia, 5 minutes after the onset of bypass during cooling, at the onset of CA or LF, 5 minutes after resumption of bypass, at 32[degree sign]C (rectal) during rewarming, at 10 min after weaning from bypass, and 90 min after the end of CA. Linear regression analysis was used to examine the relationship between glucose level and perioperative neurologic outcomes assessed by ictal activity and reappearance of latency times on electroencephalography (EEG), creatine phosphokinase brain-isoenzyme (CK-BB) release, and blinded neurologic examination. Results: Higher glucose levels prior to CA were associated with increased CK-BB release in the first 6 hours after surgery (P<0.01), but had no relation to seizure activity. Longer duration of CA was associated with higher blood glucose levels at 32[degree sign] during rewarming (P<0.001), at 10 minutes after bypass (P<0.01) and 90 minutes after the end of CA (P=0.03). Glucose and EEG recovery times following CA were inversely related. Lower, but not hypoglycemic, glucose levels at 10 min after CPB and 90 min after CA were associated with increased EEG seizure activity in the initial 48 hrs postoperative (P<0.04). Conversely, intraoperative hyperglycemia was associated with shorter EEG recovery times and a low incidence of postoperative seizures. Pre- and post CA glucose levels were not associated with clinical siezures, nor abnormal neurologic examination or repeat EEG at time of discharge. (Figure 1)Figure 1Conclusions: The data reported here are observational and allow only conclusions related to associations between neurologic outcome and glucose level, nevertheless, the faster recovery of EEG latency with reduced ictal activity following CA suggests that high serum glucose may not be harmful during infant cardiac surgery with prolonged periods of cerebral ischemia. While in contrast to adult data, these findings are consistent with experimental data in immature animals undergoing cerebral ischemia.