Therapeutic hypothermia can be induced and maintained using either commercial water bottles or a “phase changing material” mattress in a newborn piglet model
- S Iwata1,2,
- O Iwata1,2,
- L Olson3,
- A Kapetanakis1,
- T Kato1,
- S Evans1,
- Y Araki4,
- T Kakuma4,
- T Matsuishi2,
- F Setterwall5,
- H Lagercrantz3,
- N J Robertson1
- 1Academic Neonatology, EGA UCL Institute for Women’s Health, University College London, London, UK
- 2Center for Developmental and Cognitive Neuroscience, Department of Pediatrics, Kurume University School of Medicine, Kurume, Fukuoka, Japan
- 3Department of Woman and Child Health, Karolinska Institute, Stockholm, Sweden
- 4Centre for Bio-Statistics, Kurume University School of Medicine, Kurume, Fukuoka, Japan
- 5Department of Chemical Engineering, Royal Institute of Technology, Stockholm, Sweden
- 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}orbix.uk.net
- Accepted 7 January 2009
- Published Online First 20 January 2009
Abstract
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.
Footnotes
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Competing interests: None.
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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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‣ Additional material is published online only at http://adc.bmj.com/content/vol94/issue5
