A pilot cohort study of cerebral autoregulation and 2-year neurodevelopmental outcomes in neonates with hypoxic-ischemic encephalopathy who received therapeutic hypothermia

BACKGROUND: Neurodevelopmental disabilities persist in survivors of neonatal hypoxic-ischemic encephalopathy (HIE) despite treatment with therapeutic hypothermia. Cerebrovascular autoregulation, the mechanism that maintains cerebral perfusion during changes in blood pressure, may influence outcomes. Our objective was to describe the relationship between acute autoregulatory vasoreactivity during treatment and neurodevelopmental outcomes at 2 years of age. METHODS: In a pilot study of 28 neonates with HIE, we measured cerebral autoregulatory vasoreactivity with the hemoglobin volume index (HVx) during therapeutic hypothermia, rewarming, and the first 6 h of normothermia. The HVx, which is derived from near-infrared spectroscopy, was used to identify the individual optimal mean arterial blood pressure (MAP(OPT)) at which autoregulatory vasoreactivity is greatest. Cognitive and motor neurodevelopmental evaluations were completed in 19 children at 21–32 months of age. MAP(OPT), blood pressure in relation to MAP(OPT), blood pressure below gestational age + 5 (ga + 5), and regional cerebral oximetry (rSO(2)) were compared to the neurodevelopmental outcomes. RESULTS: Nineteen children who had HIE and were treated with therapeutic hypothermia performed in the average range on cognitive and motor evaluations at 21–32 months of age, although the mean performance was lower than that of published normative samples. Children with impairments at the 2-year evaluation had higher MAP(OPT) values, spent more time with blood pressure below MAP(OPT), and had greater blood pressure deviation below MAP(OPT) during rewarming in the neonatal period than those without impairments. Greater blood pressure deviation above MAP(OPT) during rewarming was associated with less disability and higher cognitive scores. No association was observed between rSO(2) or blood pressure below ga + 5 and neurodevelopmental outcomes. CONCLUSION: In this pilot cohort, motor and cognitive impairments at 21–32 months of age were associated with greater blood pressure deviation below MAP(OPT) during rewarming following therapeutic hypothermia, but not with rSO(2) or blood pressure below ga + 5. This suggests that identifying individual neonates’ MAP(OPT) is superior to using hemodynamic goals based on gestational age or rSO(2) in the acute management of neonatal HIE. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12883-015-0464-4) contains supplementary material, which is available to authorized users.