Background: Therapeutic hypothermia is a safe and effective therapy for neonatal encephalopathy in an intensive care setting; development of simple and safe cooling methods for use in low-resource settings may increase the number of infants likely to benefit from therapeutic hypothermia.
Aims/Methods: To assess two low-tech, low-cost cooling devices: (i) commercially available water bottles filled with tepid water (25°C); (ii) phase changing material (PCM) with a melting point 32°C (PCM works as a heat buffer at this temperature). Eleven anaesthetized newborn piglets were studied following transient hypoxia-ischaemia. The cooling device was applied between 2-26h after hypoxia-ischaemia with the target rectal temperature (Trectal) 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 the: (a) total period within target Trectal range; (b) stability and fluctuation of Trectal during cooling.
Results: Therapeutic hypothermia was achieved with both water bottles (n=5) and PCM mattress (n=6). The time to reach target Trectal was (i) water bottle: 1.8 (0.5) and (ii) PCM: 1.9 (0.3)h (mean (SD)). PCM cooling led to a longer period within target Trectal (p < 0.01) and more stable cooling (p < 0.05). Water bottle cooling required device renewal (4 of 5).
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 the water bottle.