Pediatric research
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Observational Study
Later cooling within 6 h and temperatures outside 33-34 °C are not associated with dysfunctional autoregulation during hypothermia for neonatal encephalopathy.
Cooling delays, temperature outside 33-34 °C, and blood pressure below the mean arterial blood pressure with optimal cerebral autoregulation (MAPOPT) might diminish neuroprotection from therapeutic hypothermia in neonates with hypoxic-ischemic encephalopathy (HIE). We hypothesized that longer time to reach temperature <34 °C and having temperature outside 33-34 °C would be associated with worse autoregulation and greater brain injury. ⋯ Cooling time to reach target hypothermia temperature within 6 h of birth did not affect cerebral autoregulation measured by NIRS in neonates with hypoxic-ischemic encephalopathy (HIE). Temperature fluctuations >33-34 °C were associated with blood pressures that exceeded the range of optimal autoregulatory vasoreactivity. Cooling time within 6 h of birth and temperatures >33-34 °C were not associated with qualitative brain injury on MRI. Regional apparent diffusion coefficient scalars on diffusion tensor imaging MRI were not appreciably affected by cooling time or temperature >33-34 °C. Additional research in a larger and more heterogeneous population is needed to determine how delayed cooling and temperatures beyond the target hypothermia range affect autoregulation and brain injury.