Colin Grissom, M.D. "New Hope For Surviving the Avalanche"
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Avalanche Victim Mortality
Asphyxiation is the most common cause of death during avalanche burial. About
75% of avalanche deaths are due to asphyxiation, about 25% to trauma, and very few to
hypothermia
5, 13, 17, 23
. Because asphyxiation is the major cause of death during avalanche
burial, time to extrication is a major determinant of survival. Fully buried avalanche
victims have a greater than 90% chance of survival if extricated within 15 minutes, but
only 30% after about 35 minutes (Figure 1)
7, 9
, emphasizing the need for companion
rescue at the avalanche site. Survival beyond 30 minutes of burial requires an air pocket
for breathing, and if the air pocket is large enough, avalanche victims may survive for
hours and develop severe hypothermia.
Figure 1. Data from Switzerland for survival probability for completely buried avalanche
victims in open areas 1981-1998 (n=638) in relation to time buried (minutes) under the
snow. Median extrication time was 37 minutes. The dotted curve represents the survival
function for completely buried avalanche victims in open areas (n=422) based on the
Swiss data for 1981-1991 as calculated by Falk and colleagues
9
. (From reference
7
).
Survival Chances in an Avalanche
Because death during avalanche burial most commonly occurs from asphyxiation
within the first 15 to 35 minutes, rapid extrication is the most important determinant of
survival. Other factors that influence survival include burial depth (no avalanche victim
buried deeper than 7 feet has been recovered alive in the U.S.), exposed body parts or
objects attached to the victim, and ability to self rescue in a shallow burial. If avalanche
burial victims are unable to extricate themselves, then the greatest chance of survival
rests with companion rescue using a hasty search for surface clues and an avalanche
transceiver with a probe and shovel. Organized rescue teams generally arrive on scene
after 35 minutes have elapsed since avalanche burial, and chances of survival are lower.
0%
20%
40%
60%
80%
100%
0
20
40
60
80 100 120 140 160 180 200 220 240
Time buried under avalanche (min)
Survival probability
