Cerebrovascular autoregulation and neurologic injury in neonatal hypoxic-ischemic encephalopathy

BACKGROUND: Neonates with hypoxic-ischemic encephalopathy (HIE) are at risk of cerebral blood flow dysregulation. Our objective was to describe the relationship between autoregulation and neurologic injury in HIE. METHODS: Neonates with HIE had autoregulation monitoring with the hemoglobin volume index (HVx) during therapeutic hypothermia, rewarming, and the first 6 h of normothermia. The 5-mmHg range of mean arterial blood pressure (MAP) with best vasoreactivity (MAP(OPT)) was identified. The percentage of time spent with MAP below MAP(OPT) and deviation in MAP from MAP(OPT) were measured. Neonates received brain MRIs 3–7 days after treatment. MRIs were coded as no, mild, or moderate/severe injury in five regions. RESULTS: HVx identified MAP(OPT) in 79% (19/24), 77% (17/22), and 86% (18/21) of neonates during hypothermia, rewarming, and normothermia, respectively. Neonates with moderate/severe injury in paracentral gyri, white matter, basal ganglia, and thalamus spent a greater proportion of time with MAP below MAP(OPT) during rewarming than neonates with no or mild injury. Neonates with moderate/severe injury in paracentral gyri, basal ganglia, and thalamus had greater MAP deviation below MAP(OPT) during rewarming than neonates without injury. CONCLUSION: Maintaining MAP within or above MAP(OPT) may reduce the risk of neurologic injuries in neonatal HIE.