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Therapeutic hypothermia can be induced and maintained using either commercial water bottles or a “phase changing material” mattress in a newborn piglet model
  1. S Iwata1,2,
  2. O Iwata1,2,
  3. L Olson3,
  4. A Kapetanakis1,
  5. T Kato1,
  6. S Evans1,
  7. Y Araki4,
  8. T Kakuma4,
  9. T Matsuishi2,
  10. F Setterwall5,
  11. H Lagercrantz3,
  12. N J Robertson1
  1. 1
    Academic Neonatology, EGA UCL Institute for Women’s Health, University College London, London, UK
  2. 2
    Center for Developmental and Cognitive Neuroscience, Department of Pediatrics, Kurume University School of Medicine, Kurume, Fukuoka, Japan
  3. 3
    Department of Woman and Child Health, Karolinska Institute, Stockholm, Sweden
  4. 4
    Centre for Bio-Statistics, Kurume University School of Medicine, Kurume, Fukuoka, Japan
  5. 5
    Department of Chemical Engineering, Royal Institute of Technology, Stockholm, Sweden
  1. Dr Osuke Iwata, Center for Developmental and Cognitive Neuroscience, Department of Pediatrics, Kurume University School of Medicine, 67 Asahimachi, Kurume, Fukuoka, 830-0011 Japan; o.iwata{at}


Background: Therapeutic hypothermia, a safe and effective treatment for neonatal encephalopathy in an intensive care setting, is not available in low-resource settings.

Aims/Methods: To assess two low-tech, low-cost cooling devices for use in low-resource settings: (i) commercially available water bottles filled with tepid water (25°C); (ii) a mattress made of phase changing material (PCM) with a melting point of 32°C (PCM works as a heat buffer at this temperature). Eleven anaesthetised newborn piglets were studied following transient hypoxia–ischaemia. The cooling device was applied 2–26 h after hypoxia–ischaemia with a target rectal temperature (Trectal) of 33–34°C. Trectal undershoot was adjusted using cotton blankets; the cooling device was renewed when Trectal rose above 35°C. Trectal data during cooling were dichotomised (within or without target) to assess: (a) the total period within the target Trectal range; (b) the stability and fluctuation of Trectal during cooling.

Results: Therapeutic hypothermia was achieved with both water bottles (n = 5) and the PCM mattress (n = 6). The mean (SD) time to reach target Trectal was 1.8 (0.5) h with water bottles and 1.9 (0.3) h with PCM. PCM cooling led to a longer period within the target Trectal range (p<0.01) and more stable cooling (p<0.05). Water bottle cooling required device renewal (in four out of five piglets).

Conclusion: Simple, low-tech cooling devices can induce and maintain therapeutic hypothermia effectively in a porcine model of neonatal encephalopathy, although frequent fine tuning by adjusting the number of blankets insulating the piglet was required to maintain a stable temperature. PCM may induce more stable cooling compared with water bottles.

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  • Competing interests: None.

  • Funding: This work was undertaken at UCLH/UCL who received a proportion of funding from the United Kingdom Department of Health’s NIHR Biomedical Research Centres funding scheme.

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