Colin Grissom, M.D. "New Hope For Surviving the Avalanche"
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for the purposes of the algorithm presented in Figure 5. Most avalanche victims
extricated in cardiac arrest, however, have died from asphyxiation and continuing
resuscitation efforts until rewarming occurs is unlikely to result in survival. This is
especially true if no air pocket for breathing is present or if the upper airway is obstructed
by snow. In a study by Locher there were no survivors after resuscitation efforts among
13 avalanche victims who were found in cardiac arrest after burials of 30 to 165 minutes
duration, suggesting that cardiac arrest was due to asphyxiation rather than
hypothermia
17
. An air pocket for breathing must be present for an avalanche burial victim
to survive long enough to develop severe hypothermia. If an air pocket for breathing is
not present then the avalanche victim extricated from snow burial in cardiac arrest has
likely died from trauma or asphyxiation.
Hypothermia in the Avalanche Burial Victim
In avalanche burial victims who are extricated alive, hypothermia is the major
medical problem that will require treatment
4, 6, 7
. Clinical definitions of hypothermia
severity with core body temperature correlates are shown in Table 3. As the patient is
extricated from snow burial warm dry insulation is provided during packaging and wet
clothing is removed as soon as is practical. If the patient is unconscious then moderate or
severe hypothermia is suspected and they are handled gently to avoid precipitating VF. If
clinically indicated for treatment of moderate or severe hypothermia, intravenous access
is obtained and warmed isotonic fluid is infused (43 ° C). If the patient is unconscious,
then intubation is appropriate to provide adequate oxygenation and ventilation with
heated (42 to 46 ° C) humidified oxygen. The goal of pre-hospital treatment of moderate
to severe hypothermia is to limit afterdrop during medical transport to a hospital where
definitive rewarming can occur. The patient with mild hypothermia who is shivering can
rewarm in the field if dry insulation is provided. If the patient is conscious and alert,
warm fluids containing sugar may be given by mouth. If possible, patients with mild
hypothermia should remain supine until rewarming has occurred in order to prevent a
greater afterdrop from ambulation. Optimally, the severity of hypothermia is determined
by a core body temperature measurement in the field, preferably using an esophageal
probe, but tympanic membrane sensors or rectal probes may also be used. If core body
temperature cannot be measured in the field then the severity of hypothermia may be
estimated in the field using the Swiss Hypothermia Stages I to IV that are determined by
the clinical presentation (Table 3)
4
.
The severity of hypothermia may also be estimated from the time buried and the
average rate of core temperature cooling during avalanche burial. Grissom and colleagues
have measured core temperature cooling rate during snow burial in a controlled
experimental set-up. In subjects buried in dense snow for up to 60 minutes wearing a
lightweight clothing insulation system while breathing with an artificial device (the
AvaLung), core body temperature cooling rate was about 1.3 ° C/hr
11
.
Retrospective studies of core temperature on hospital arrival by Locher
17
suggest
that average core temperature cooling rate is 3 ° C/hr (range 0.75 to 4.75 ° C/hr in
survivors), greater than the 1.3 ° C/hr estimated by Grissom and colleagues. The higher
rate of cooling reported by Locher is based on a known time of burial and known time of
arrival at the hospital where core body temperature was recorded, and does not
