Abstract Presentations at the 2005 Wilderness Medical Society Meeting, Snowmass,
Colorado, July 23 to 27, 2005
Poster Presentation
Core Body Temperature Afterdrop and Rewarming After Burial in Snow
Colin K. Grissom, MD
1
, Chris H. Harmston, MSE
2
, John C. McAlpine, MD
3
, Martin I.
Radwin, MD
4
, Brad Ellington, DO
5
, Ellie Hirshberg, MD
1
.
1
Pulmonary and Critical Care Division, Department of Medicine, LDS Hospital and the
University of Utah, Salt Lake City, Utah
2
Sorenson Genomics, Salt Lake City, Utah
3
University of British Columbia, Vancouver, British Columbia, Canada
4
Granger Medical Clinic, West Valley City, Utah
5
University of Missouri, Kansas City, Department of Emergency Medicine
Introduction: Core body temperature afterdrop may occur after extrication of
hypothermic avalanche burial victims.
Objective: The objective of this study was to measure the decrease in core body
temperature after extrication from snow burial (afterdrop) and measure core body
temperature during passive rewarming in the field.
Methods: Esophageal core body temperature (T
e
) was measured in 6 subjects buried in
compacted snow (mean density 39%) for up to 60 minutes at an altitude of 8,000 ft (P
b
571 mm Hg). Subjects breathed with an AvaLung (Black Diamond Equipment, Salt Lake
City, Utah) device during snow burial. Mean snow temperature was -3.5
±1.0 º C and
mean ambient air temperature was 0
±2 º C. Subjects were dressed in a lightweight
clothing insulation system consisting of a one-piece Gore-TexTM suit over medium
weight CapileneTM underwear with a hood, face mask, goggles, mittens, and warm boots.
After extrication from snow burial subjects breathed ambient air as they were hastily
placed in a sleeping bag wrapped in a blanket on an insulating pad. Heavy plastic was
wrapped around all insulating layers to complete the hypothermia wrap. Core body
temperature was measured for an additional 60 minutes as subjects were allowed to
passively rewarm by shivering.
Results: T
re
cooling rate during snow burial was 0.8
±0.3 º C/hr during a mean burial
time of 58
±4 minutes. T
re
afterdrop occurred over 12
±8 minutes after extrication from
snow burial with a T
re
cooling rate of 4.0
±0.8 º C/hr (p<0.001 T
re
cooling rate during
snow burial versus afterdrop). Rewarming occurred after the nadir of the T
re
at a rate of
1.1
±0.3 º C/hr over the subsequent 48 ±8 minutes during passive rewarming (p=0.05
snow burial cooling versus passive rewarming rate of T
re
).
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.
