Dear Editor,
Leclerc et al. (2023) are to be congratulated for their experiments in which they compared heat transfer capabilities of three commercially available surface cooling devices. Such studies are useful when it comes to selecting a device that can be used for patient temperature management and understanding how patient conditions impact its effectiveness. The heat flux measured for the standard cooling blanket used in this study of unmedicated volunteers was about 250 W after 30 minutes of operation, which yielded a core-cooling rate of 0.07°C/h. In contrast, Plattner et al. (1997) cooled paralyzed, anesthetized subjects using a similar cooling blanket and measured 200 W of heat flux, but this was associated with a 1.6°C/h drop in core temperature—23 times the cooling rate measured in the unmedicated subjects of the current study. This demonstrates the strong capability of the intact thermoregulatory system to resist temperature reduction. The study by Plattner et al. (1997) also demonstrated the very high heat flux provided by immersion in an ice water bath (600–800 W). This produced a core-cooling rate of 9.7°C/h, which was six times as fast as the cooling blanket. The ice water immersion method furthermore suppresses shivering, enabling rapid cooling to occur in the absence of paralysis (Proulx et al., 2003).
There is currently one U.S. Food and Drug Administration-cleared device, the ThermoSuit System (Life Recovery Systems, Kinnelon, NJ, USA), that cools with the ice water immersion method. It has been reported to have a cooling rate of 9.6°C/h in unmedicated hyperthermic subjects (Tan et al., 2017). Further studies examining the clinical use of the above and other cooling methods for various indications will be helpful for guiding future treatment guidelines.
