Elsevier

The Journal of Pediatrics

Volume 220, May 2020, Pages 73-79.e3
The Journal of Pediatrics

Original Article
An In Vivo Assessment of Regional Brain Temperature during Whole-Body Cooling for Neonatal Encephalopathy

https://doi.org/10.1016/j.jpeds.2020.01.019Get rights and content

Objective

To assess differences in regional brain temperatures during whole-body hypothermia and test the hypothesis that brain temperature profile is nonhomogenous in infants with hypoxic–ischemic encephalopathy.

Study design

Infants with hypoxic–ischemic encephalopathy were enrolled prospectively in this observational study. Magnetic resonance (MR) spectra of basal ganglia, thalamus, cortical gray matter, and white matter (WM) were acquired during therapeutic hypothermia. Regional brain tissue temperatures were calculated from the chemical shift difference between water signal and metabolites in the MR spectra after performing calibration measurements. Overall difference in regional temperature was analyzed by mixed-effects model; temperature among different patterns and severity of injury on MR imaging also was analyzed. Correlation between temperature and depth of brain structure was analyzed using repeated-measures correlation.

Results

In total, 53 infants were enrolled (31 girls, mean gestational age: 38.6 ± 2 weeks; mean birth weight: 3243 ± 613 g). MR spectroscopy was acquired at mean age of 2.2 ± 0.6 days. A total of 201 MR spectra were included in the analysis. The thalamus, the deepest structure (36.4 ± 2.3 mm from skull surface), was lowest in temperature (33.2 ± 0.8°C, compared with basal ganglia: 33.5 ± 0.9°C; gray matter: 33.6 ± 0.7°C; WM: 33.8 ± 0.9°C, all P < .001). Temperatures in more superficial gray matter and WM regions (depth: 21.9 ± 2.4 and 21.5 ± 2.2 mm) were greater than the rectal temperatures (33.4 ± 0.4°C, P < .03). There was a negative correlation between temperature and depth of brain structure (rrm = −0.36, P < .001).

Conclusions

Whole-body hypothermia was effective in cooling deep brain structures, whereas superficial structures were warmer, with temperatures significantly greater than rectal temperatures.

Section snippets

Methods

Infants with HIE admitted to the Children's Hospital Los Angeles for therapeutic hypothermia from December 2012 to November 2018 were screened for study enrollment. Selection criteria for therapeutic hypothermia were similar to the National Institute of Child Health and Human Development's cooling trial.26 Passive cooling was initiated at the referring hospital. Active cooling during transport (Tecotherm, Inspiration Healthcare, United Kingdom) became standard after July 2017. All infants

Results

From December 2012 to November 2018, 58 infants with HIE were enrolled. After excluding infants for gestational age <35 weeks (1), multiple congenital anomalies (2), perinatal stroke (1), and poor MR spectra quality (1), a total of 201 MR spectra from 53 infants (22 boys, 31 girls) were included in the final analysis. WM spectra were not acquired in the first 11 patients. Mean gestational age and birth weight were 38.6 ± 2 weeks and 3243 ± 613 g, respectively. Mean age at time of MR spectra

Discussion

Using MR thermometry, we measured temperatures of various brain structures that were at risk of hypoxic–ischemic injury and correlated the measurements to physical depth of tissue and characteristic of brain injury. The results of this investigation revealed that whole-body therapeutic hypothermia effectively lowered deep gray matter structures, whereas temperatures of more superficial structures such as gray matter and WM were slightly, but significantly greater, than rectal temperatures.

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    • Effects of Tissue Temperature and Injury on ADC during Therapeutic Hypothermia in Newborn Hypoxic-Ischemic Encephalopathy

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    This study was supported by funding from Rudi Schulte Research Institute and Reiling Family Foundation.

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