Evolution of encephalopathy during whole body hypothermia for neonatal hypoxic-ischemic encephalopathy

Objective: To examine the predictive ability of stage of hypoxic-ischemic encephalopathy (HIE) for death or moderate/severe disability at 18 months among neonates undergoing hypothermia.

Study design: Stage of encephalopathy was evaluated at <6 hours of age, during study intervention, and at discharge among 204 participants in the National Institute of Child Health and Human Development Neonatal Research Network Trial of whole body hypothermia for HIE. HIE was examined as a predictor of outcome by regression models.

Results: Moderate and severe HIE occurred at <6 hours of age among 68% and 32% of 101 hypothermia group infants and 60% and 40% of 103 control group infants, respectively. At 24 and 48 hours of study intervention, infants in the hypothermia group had less severe HIE than infants in the control group. Persistence of severe HIE at 72 hours increased the risk of death or disability after controlling for treatment group. The discharge exam improved the predictive value of stage of HIE at <6 hours for death/disability.

Conclusions: On serial neurologic examinations, improvement in stage of HIE was associated with cooling. Persistence of severe HIE at 72 hours and an abnormal neurologic exam at discharge were associated with a greater risk of death or disability.