Abstract
Introduction:
The precise temperature for optimal neuroprotection in infants with neonatal encephalopathy is unclear. Our aim was to assess systemic effects of whole-body cooling to 35 °C, 33.5 °C, and 30 °C in a piglet model of perinatal asphyxia.
Methods:
Twenty–eight anesthetized male piglets aged <24 h underwent hypoxia–ischemia (HI) and were randomized to normothermia or cooling to rectal temperature (Trec) 35 °C, 33.5 °C, or 30 °C during 2–26 h after insult (n = 7 in each group). HR, MABP, and Trec were recorded continuously.
Results:
Five animals cooled to 30 °C had fatal cardiac arrests. During 30 °C cooling, heart rate (HR) was lower vs. normothermia (P < 0.001). Although mean arterial blood pressure (MABP) did not vary between groups, more fluid boluses were needed at 30 °C than at normothermia (P < 0.02); dopamine use was higher at 30 °C than at normothermia or 35 °C (P = 0.005 and P = 0.02, respectively). Base deficit was increased at 30 °C at 12, 24, and 36 h vs. all other groups (P < 0.05), pH was acidotic at 36 h vs. normothermia (P = 0.04), and blood glucose was higher for the 30 °C group at 12 h vs. the normothermia and 35 °C groups (P < 0.05). Potassium was lower at 12 h in the 30 °C group vs. the 33.5 °C and 35 °C groups. There was no difference in cortisol level between groups.
Discussion:
Cooling to 30 °C led to metabolic derangement and more cardiac arrests and deaths than cooling to 33.5 °C or 35 °C. Inadvertent overcooling should be avoided.
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Acknowledgements
We thank Paul Basset for statistical support; Neil Sebire and Elizabeth Powell for organ pathology assessment; David Cox, Alan Groves, Mark Busbridge, and Richard Chapman for serum troponin assessment.
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Kerenyi, A., Kelen, D., Faulkner, S. et al. Systemic effects of whole-body cooling to 35 °C, 33.5 °C, and 30 °C in a piglet model of perinatal asphyxia: implications for therapeutic hypothermia. Pediatr Res 71, 573–582 (2012). https://doi.org/10.1038/pr.2012.8
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DOI: https://doi.org/10.1038/pr.2012.8
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