In a recent article released in Wilderness and Environmental Medicine, a team looked at the application of cooling packs to specific areas of the body in an attempt to optimize cooling in austere environments where cooling baths may not be available. The paper explains that the extent to heat injury is directly related to both the magnitude and duration of hyperthermia, and therefore prompt cooling is of the essence.
They looked at 10 adult males who underwent exercise induced heat stress (defined as a core temperature over 39.2°C) incurred over a set time period of 30-40 minutes. During the rest phase (which occurred in a warm environment with additional placement of mittens, boots and a balaclava) the subjects underwent one of three treatments: no cooling (control), one cold pack to bilateral neck, axillae and groin (standard care) or one cold pack to bilateral cheeks, palms and soles. They found that the application of the cold packs to the cheeks, palms and soles decreased the core temperature by
0.6°C in the first 5 minutes vs. 0.4°C with traditional cooling (no treatment resulted in no cooling), and continued to show a steeper decline in core body temperature through the entire 30 minutes recovery period. Females were theoretically predicted to benefit even more from this cooling given their lower rates of sweating at the forehead, chest and back and higher rates of cutaneous blood flow.
One limitation this method does have is that the extremities must not be cooled to the point that they induce local vasoconstriction which can worsen the hyperthermia. Also, this study specifically looked at young, healthy males, whereas many heat related injury occurs in the elderly who have less thermoregulatory ability, worse cardiovascular/pulmonary/renal function and are taking medications which may inhibit some thermoregulatory mechanisms such as sweating.
Additionally, this study used chemical cold packs which were previously found to be inferior to similarly sized ice-packs in the cooling of hyperthermic patients***. Therefore, it would be very interesting to know how the application of ice packs instead of the coolin packs would affect the rate of cooling in these patients. Although the study looks at a very select population, the results provide evidence for enhanced cooling using a simple manipulation in the location of placement of cooling packs when these are the only method of cooling you have available and it is worth considering as we enter the warmest parts of the year.
Lissoway, J., Lipman, G., Grahn, D., Cao, V., Shaheen, M., Phan, S., . . . Heller, C. (n.d.). A Randomized Controlled Trial of a Novel Application of Chemical Cold Packs for Treatment of Exercise-Induced Hyperthermia. Wilderness & Environmental Medicine,118-118.
***Phan, S., Lissoway, J., & Lipman, G. (n.d.). Chemical Cold Packs May Provide Insufficient Enthalpy Change for Treatment of Hyperthermia. Wilderness & Environmental Medicine, 37-41.