Outcomes for Newborns with Mild Hypoxic-Ischemic Encephalopathy: A Retrospective Study

Background: HIE remains a significant cause of mortality and long-term disability in late preterm and term newborns. At birth, the only available distinction between mild, moderate, and severe HIE is based on the clinical ground. Nevertheless, mild HIE can be presented with subtle or subjective clinical features which may mislead the treating physician and delay his decision to intervene. Methods: This is a retrospective descriptive study examined all inborn newborns ≥ 35 weeks gestational age born at a single, tertiary level Neonatal Intensive Care Unit (NICU) in women’s hospital. The study revised newborns who were admitted to NICU during the period from November 2014 till November 2020 under the diagnoses of mild HIE. The decision to start therapeutic hypothermia in cases of mHIE was off-label and it was taken according to the clinical judgment of the treating team. Results: Out of the 265 newborns admitted with a history suggestive of HIE or neurological deficits, only 116 newborns matched the diagnosis of mHIE according to the above-mentioned exclusions. 19 newborns out of the 116 mHIE cases received therapeutic hypothermia. Antepartum and or intrapartum complications were recorded in 48 mothers including an infant of insulin-dependent diabetic mother 12, pre-eclampsia 3, cord prolapse 2, shoulder dystocia 2, antepartum hemorrhage 8, chorioamnionitis 6, poor CTG tracing 13, and ruptured uterus 2. Mean gestation was 38±2 weeks, mean birth weight was 3.0±0.5 kg, Cesarean section was 57 % in the un-cooled group vs 75% in the cooled group. Mean Apgar score at 10th minute was 7.9±1.8 vs 5.3±2.2 in the un-cooled vs cooled group, the p-value is 0.002. Arterial cord pH was 7.15±0.3 vs 6.92±0.26. The base deficit in the first-hour blood gas was -7.83±5 vs -12± 5.6 (P=0.005). The Total number of cooled newborns was 19 (16%). Respiratory support was required in 76% of un-cooled newborns vs 95 % of cooled newborns. Most of the newborns have achieved full sucking power within 10 days (99%). Cooled newborns had to stay longer in the NICU because of the added number of cooling where the length of stay was 11±4.7 days vs 6.9±4.7 days in un-cooled newborns. The MRI brain was done on 25 newborns, 12 MRIs were reported as abnormal (48 %) and consistent with hypoxic-ischemic changes, 5/97 in the un-cooled cases and 7 in the cooled cases. Neurodevelopmental assessments at 12 months and 18 months of age were abnormal in 14/116 newborns (12%). Conclusion: The current assumptions about the benignity of mild form of HIE may not be accurate. More attention to this category of HIE, clear diagnostic criteria, longer clinical observation, and vigilant neurological assessment are all required.