P2.G133: Outcomes of Neonates with Mild Hypoxic-Ischemic Encephalopathy treated with Therapeutic Hypothermia: A Single-Center Retrospective Cohort Study

Background: Neonatal hypoxic-ischemic encephalopathy (HIE) remains a significant contributor to neurodevelopmental impairment and mortality. Currently therapeutic hypothermia (TH) is the standard of care for infants with moderate to severe encephalopathy. Mild HIE has not been historically treated with TH however, there has been a steady change in practice with various centers offering TH to mild HIE. In one of the prospective studies infants not treated with TH for mild HIE , disability occurred in 16% of infants at 18–22 months. We plan to look at our center's data to identify the short term and 2-year outcomes for infants with mild HIE treated with TH.

Methods: This is a retrospective cohort study, reviewing charts of neonates ≥36 weeks of GA and their mothers, admitted with a diagnosis of mild HIE and treated with TH between 2012 and 2022. All patients were classified by a neonatologist, using modified Sarnat staging. An infant’s condition was scored as mild if they had at least one domain consistent with mild but did not meet criteria for moderate or severe HIE. Infants born with severe congenital malformations or chromosomal anomalies were excluded from the study. Wilcoxon rank sum test was used for the continuous or ordinal characteristics and the Pearson’s chi-square test or Fisher’s exact test for other categorical characteristics, as appropriate.

Results: Sixty-four patients were analyzed: 53% males, 71% white, 64% cesarean section delivery, median gestational age 39.6 weeks (IQR [38.4, 40.4]), 66% required assisted ventilation at birth, 5% Epi during resus at birth, and 14% chest compressions at birth. Overall, 27% exhibited MRI findings indicative of HIE, and nearly half patients reported to have moderate/severe (27%/20%) background EEG abnormality in the first 24 hours of life. The median days to full enteral PO feeds were 6.5 (IQR [5.0, 9.0]), and the median length of NICU stay was 9.0 days (IQR [7.5, 14.0]). Out of the 64 neonates, 39 had Bayley evaluation at mean age of 22±2 months of age. Abnormal Bayley (Scores < 85 in either language, cognitive or motor scores) was detected in 6 infants (15%). In the infants without Bayley evaluation, 17 infants had pediatrician follow up between 18-24 months with 3 infants (18%) having documented developmental delays. Comparison between groups with and without Bayley screening revealed no significant differences in demographics or short-term outcomes such as abnormal MRI, LOS, background EEG. Of all, 16% of neonates displayed developmental delays, with 13% experiencing seizures and almost all falling in the first 24hrs.

Conclusion: Our single-center study suggests that neurodevelopmental outcomes in neonates with mild HIE treated with TH align with those reported in prospective studies of infants not undergoing TH. However, the necessity for randomized controlled trials to ascertain TH's efficacy in mild HIE is emphasized.