Item: Rewarming mild hypothermia after avalanche burial
Title: Rewarming mild hypothermia after avalanche burial
Proceedings: Proceedings of the 2006 International Snow Science Workshop, Telluride, Colorado
Authors: Colin K. Grissom, MD, Chris H. Harmston, MSE, John C. McAlpine, MD, Martin I. Radwin, MD, Brad Ellington, DO, Ellie Hirshberg, MD. LDS Hospital and the University of Utah, Salt Lake City, Utah
Abstract: Purpose: To determine if mildly hypothermic avalanche burial victims can be rewarmed in the field we measured esophageal core body temperature (Tes) during snow burial and after extrication during passive rewarming in a hypothermia wrap. Methods: 6 subjects were buried in compacted snow (mean density 39%) for up to 60 minutes at an altitude of 2450 m (barometric pressure 571 mm Hg) while breathing with an AvaLung (Black Diamond Equipment, Salt Lake City, Utah). Mean snow temperature was -3.5 ±1.0ºC and mean air temperature was 0 +2ºC. Subjects wore a one-piece Gore-Tex™ suit over medium weight Capilene™ underwear with a hood, face mask, goggles, mittens, and boots. After extrication from snow burial subjects were placed in a sleeping bag wrapped in a blanket on an insulating pad. All layers were wrapped in heavy plastic. Tes was measured for an additional 60 minutes as subjects rewarmed by shivering. Results: Tes cooling rate during snow burial was 0.8 ±0.3ºC/hr during a mean burial time of 58 ±4 minutes. Tes continued to decrease for 12 +8 minutes after extrication from snow burial (afterdrop) at a cooling rate of 4.0 ±0.8ºC/hr (p<0.001 Tes cooling rate during snow burial versus afterdrop cooling rate). Rewarming occurred at a rate of 1.1 ±0.3ºC/hr over the subsequent 48 ±8 minutes (p=0.05 snow burial cooling versus passive rewarming rate). Conclusion: Core body temperature cooling rate after extrication from snow burial increased about fourfold for a transient time period in subjects who were placed as quickly as possible into an insulating hypothermia wrap. Passive rewarming increased core body temperature at about the same rate that it decreased during snow burial. These findings suggest that field rewarming of avalanche burial victims with mild hypothermia who are shivering is possible, but they should be insulated quickly to limit the significant afterdrop that may occur.
Keywords: avalanche burial, avalanche rescue, hypothermia, afterdrop
Digital Abstract Not Available