Cerebrovascular autoregulation and neurologic injury in neonatal hypoxic-ischemic encephalopathy.

Howlett, Jessica A; Northington, Frances J; Gilmore, Maureen M; Tekes, Aylin; Huisman, Thierry A G M; Parkinson, Charlamaine; Chung, Shang-En; Jennings, Jacky M; Jamrogowicz, Jessica J; Larson, Abby C; Lehmann, Christoph U; Jackson, Eric; Brady, Ken M; Koehler, Raymond C; Lee, Jennifer K

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-mm Hg range of mean arterial blood pressure (MAP) with best vasoreactivity (MAPOPT) was identified. The percentage of time spent with MAP below MAPOPT and deviation in MAP from MAPOPT were measured. Neonates received brain magnetic resonance imaging (MRI) 3-7 d after treatment. MRIs were coded as no, mild, or moderate/severe injury in five regions. RESULTS HVx identified MAPOPT in 79% (19/24), 77% (17/22), and 86% (18/21) of the 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 MAPOPT 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 MAPOPT during rewarming than neonates without injury. CONCLUSION Maintaining MAP within or above MAPOPT may reduce the risk of neurologic injuries in neonatal HIE.