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Heat transfer coefficient: Medivance Arctic Sun® Temperature Management System vs. water immersion

Published online by Cambridge University Press:  01 July 2008

M. J. English  and
T. M. Hemmerling
M. J. English*
Affiliation:
McGill University, Department of Anesthesiology, Montreal, Quebec, Canada
T. M. Hemmerling
Affiliation:
McGill University, Department of Anesthesiology, Montreal, Quebec, Canada
*
Department of Anesthesiology, D10-157.2, Montreal General Hospital, 1650 Cedar Avenue, Montreal H3G 1A4, Quebec, Canada. E-mail: mike.english@mac.com; Tel: +1 514 934 1934 Ext. 43261; Fax: +1 514 934 8249
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Summary

Background and objective

To improve heat transfer, the Medivance Arctic Sun® Temperature Management System (Medivance, Inc., Louisville, CO, USA) features an adhesive, water-conditioned, highly conductive hydrogel pad for intimate skin contact. This study measured and compared the heat transfer coefficient (h), i.e. heat transfer efficiency, of this pad (hPAD), in a heated model and in nine volunteers’ thighs; and of 10°C water (hWATER) in 33 head-out immersions by 11 volunteers.

Methods

Volunteer studies had ethical approval and written informed consent. Calibrated heat flux transducers measured heat flux (W m−2). Temperature gradient (ΔT) was measured between skin and pad or water temperatures. Temperature gradient was changed through the pad’s water temperature controller or by skin cooling on immersion.

Results

The heat transfer coefficient is the slope of W m−2/ΔT: its unit is W m−2 °C−1. Average with (95% CI) was: model, hPAD = 110.4 (107.8–113.1), R2 = 0.99, n = 45; volunteers, hPAD = 109.8 (95.5–124.1), R2 = 0.83, n = 51; and water immersion, hWATER = 107.1 (98.1–116), R2 = 0.86, n = 94.

Conclusion

The heat transfer coefficient for the pad was the same in the model and volunteers, and equivalent to hWATER. Therefore, for the same ΔT and heat transfer area, the Arctic Sun’s heat transfer rate would equal water immersion. This has important implications for body cooling/rewarming rates.

Keywords

HEAT TRANSFERHYPOTHERMIABODY TEMPERATURE REGULATION
Type
Original Article
Information
European Journal of Anaesthesiology , Volume 25 , Issue 7 , July 2008 , pp. 531 - 537
Copyright
Copyright © European Society of Anaesthesiology 2008

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