Later cooling within 6 h and temperatures outside 33–34 °C are not associated with dysfunctional autoregulation during hypothermia for neonatal encephalopathy

Abstract

Background: Cooling delays, temperature outside 33–34°C, and blood pressure below the mean arterial blood pressure with optimal cerebral autoregulation (MAP OPT ) 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. Methods: Neonates with HIE had rectal temperature and near-infrared spectroscopy autoregulation monitoring during hypothermia (n=63) and rewarming (n=58). All underwent brain MRI, and a subset received diffusion tensor imaging MRI before day 10 (n=41). Results: Most neonates reached <34°C at 3–6 h of life. MAP OPT was identified in 54/63 (86%) during hypothermia and in 53/58 (91%) during rewarming. Cooling time was not related to blood pressure deviation from MAP OPT . Later cooling was associated with lower ADC scalar in unilateral posterior centrum semiovale but not in other regions. Temperatures above 34°C were associated with blood pressure above MAP OPT but not with brain injury. Conclusion: In neonates who were predominantly cooled after 3 h, cooling time was not associated with autoregulation or overall brain injury. Blood pressure deviation above MAP OPT was associated with temperature above 34°C. Additional studies are needed in a more heterogeneous population.

Wavelet Autoregulation Monitoring Identifies Blood Pressures Associated With Brain Injury in Neonatal Hypoxic-Ischemic Encephalopathy

“…After that, NIRS became standard clinical care for HIE in our NICU, and the IRB waived the requirement for written consent. Sixty-six neonates in this study were reported in at least one of our past reports ( 4 – 7 , 15 – 18 ). Four neonates contributed new data to the study.…”

“…The associations between each neonate's autoregulation and brain injury parameters were additionally analyzed with adjustments for sex, PaCO 2 level, perinatal insult score, vasopressor use, and presence of electroencephalographic seizures. We selected these covariates because of their potential associations with autoregulation and brain injury (15,23,(29)(30)(31)(32)(33).…”

“…This is a secondary and exploratory analysis of data from our prior studies (4)(5)(6)(7)(15)(16)(17)(18). No other studies have calculated MAPopt using wavelet or multi-window autoregulation monitoring in HIE to our knowledge.…”

“…Therefore, we tested 3-h periods in the current study to advance the clinical potential of autoregulation monitoring. We also adjusted the analyses for sex, vasopressor use, seizures, PaCO 2 , and the perinatal insult score because they affect autoregulation and brain injury (15,23,(29)(30)(31)(32)(33).…”

Avaliação da repercussão da hipotermia terapêutica passiva nos aspectos cardiopulmonares e neurológicos em pacientes com asfixia neonatal

“…No ano de 2017 no Japão, foi publicado um estudo que utilizou dados do "Baby Cooling Registry of Japan", que utiliza hipotermia ativa; encontrou que o resfriamento foi iniciado 6 horas após o nascimento em 96,6% dos casos; após o início da hipotermia, a temperatura corporal alvo foi atingida em uma média de 94 minutos (DP 154), e o resfriamento foi obtido em média com 312 minutos de vida (DP 183), mostrando que mesmo com hipotermia passiva, os dados do nosso estudo conseguiram demonstrar um desempenho semelhante ao das tecnologias avançadas (35) .Um outro estudo recente, realizado nos Estados Unidos e publicado nesse ano, avaliou o tempo de resfriamento e as variações de temperatura. A média de tempo para atingir a temperatura alvo foi de 240 ± 96 minutos (36) .…”