title: Superficial brain is cooler in small piglets: neonatal hypothermia implications.
abstract: OBJECTIVE
  Hypothermia was not neuroprotective in low body weight (BW) infants on subgroup analysis in a recent clinical trial of selective head cooling (SHC) in neonatal encephalopathy (CoolCap Trial).
  
  
  METHODS
  The BW dependence of regional cerebral temperature was investigated in 14 newborn piglets under normothermia (38.5 degrees C), whole-body cooling (WBC; 36.5, 34.5, 32.5, and 30.5 degrees C), or SHC (20, 15, and 10 degrees C).
  
  
  RESULTS
  Normothermia: Lower BW led to lower superficial brain temperature (p < 0.01). Deep to superficial brain and rectal to superficial brain temperature gradients increased with decreasing BW (both p < 0.05). WBC: Lower BW led to lower superficial brain temperature and higher rectal to superficial brain temperature gradient (p < 0.05 and p < 0.01, respectively). SHC: For lower BW, superficial and deep brain temperatures decreased (p < 0.01 and p < 0.05, respectively), whereas rectal to deep, rectal to superficial, and deep to superficial brain temperature gradients increased (p < 0.05, p < 0.01, and p < 0.05, respectively). Compared with SHC alone, superimposition of WBC (34.5 degrees C) reduced all regional temperatures (all p < 0.001); gradients were unaffected.
  
  
  CONCLUSIONS
  Brain cooling (under normothermia, WBC, or SHC) was more efficient with lower BW due to greater head surface area-to-volume ratios. In the CoolCap Trial, low BW infants might have been excessively cooled. WBC and SHC may require BW adjustment to accomplish consistent regional temperatures and optimal neuroprotection.
authors.affiliation: Centre for Perinatal Brain Research, Institute for Women's Health, University College London, The Rayne Institute, London, United Kingdom.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Iwata
authors.affiliation: Centre for Perinatal Brain Research, Institute for Women's Health, University College London, The Rayne Institute, London, United Kingdom.
authors.forename: Osuke
authors.initials: O
authors.lastname: Iwata
authors.affiliation: Lysholm Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, London, United Kingdom.
authors.forename: John S
authors.initials: JS
authors.lastname: Thornton
authors.affiliation: Centre for Perinatal Brain Research, Institute for Women's Health, University College London, The Rayne Institute, London, United Kingdom.
authors.forename: Shanthi
authors.initials: S
authors.lastname: Shanmugalingam
authors.affiliation: Department of Medical Physics and Bio-Engineering, University College London Hospitals NHS Foundation Trust, London, United Kingdom.
authors.forename: Alan
authors.initials: A
authors.lastname: Bainbridge
authors.affiliation: Centre for Perinatal Brain Research, Institute for Women's Health, University College London, The Rayne Institute, London, United Kingdom.
authors.forename: Donald
authors.initials: D
authors.lastname: Peebles
authors.affiliation: Centre for Perinatal Brain Research, Institute for Women's Health, University College London, The Rayne Institute, London, United Kingdom.
authors.forename: John S
authors.initials: JS
authors.lastname: Wyatt
authors.affiliation: Department of Medical Physics and Bio-Engineering, University College London Hospitals NHS Foundation Trust, London, United Kingdom.
authors.forename: Ernest B
authors.initials: EB
authors.lastname: Cady
authors.affiliation: Centre for Perinatal Brain Research, Institute for Women's Health, University College London, The Rayne Institute, London, United Kingdom.
authors.forename: Nicola J
authors.initials: NJ
authors.lastname: Robertson
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001831:Body Temperature / Q000502:physiology*; D001835:Body Weight; D001921:Brain / Q000378:metabolism*; D001930:Brain Injuries / Q000628:therapy; D007035:Hypothermia; D007036:Hypothermia, Induced; D008297:Male; D013552:Swine