Hypothermia to Treat Neonatal Hypoxic Ischemic Encephalopathy: Systematic Review

Abstract

Previous studies of hypothermia as a treatment for neonatal hypoxic-ischemic encephalopathy (HIE) have yielded mixed results. The present investigators compared the efficacy and safety of hypothermia compared with normothermia in randomized and quasi-randomized trials that were assessed independently by 2 reviewers, with discrepancies resolved by a third. Eight studies of acceptable quality were chosen based on concealment of allocation, method of randomization, masking of outcome assessment, and completeness of follow-up. The risk of both death and moderate to severe neurodevelopmental disability was significantly reduced in infants treated by hypothermia compared to control infants for whom normothermia was maintained. The relative risk was 0.76, with a 95% confidence interval of 0.65-0.88. Hypothermia-treated infants had significantly lower rates of severe neurodevelopmental disability and severe cerebral palsy, and less often had low scores on a Mental Developmental Index and Psychomotor Developmental Index. More control infants died after withdrawal of life support. Cardiac arrhythmias and thrombocytopenia were more common in neonates treated with hypothermia, but were not clinically threatening. The investigators recommend hypothermia for treating postintrapartum asphyxial HIE within 6 hours after birth-especially in neonates with moderate encephalopathy. Continued follow-up of surviving infants is vital in order to identify the long-term effects of hypothermia.