COLD INJURIES - Medicine for Mountaineering and Other Wilderness Activities - page 401

pothermic personarecollapsed, andaccessing aveinisquitedifficult evenforexperienced
individuals.
Administration of heated intravenous fluids has been suggested as a means of rewarm-
ing. However, the greatest benefit from heating intravenous fluids is avoiding further cool-
ing by the administration of fluids that are at the temperature of the environment. Four
liters of fluids heated to 104°F (40°C) and administered over a period of two hours to an
individual with a temperature of 77°F (25°C) could not transfer more than 60 kilocalories
(kcal)ofheatperhourtotheperson.Thatwouldraisethebodytemperatureofa176-pound
(80-kg) individual less than 1.8°F (1°C) per hour. More fluids would result in fluid over-
load and must not be given. At below-freezing temperatures, more heat would be lost by
radiation to the environment. The person would benefit more from evacuation to a warm
shelter.
In a hospital, severely hypothermic individuals being rewarmed with noninvasive tech-
niques increase their temperature at a rate of 0.9° to 2.7°F (0.5 to 1.5°C) per hour. In
the wilderness, rewarming would be slower. Rescuers must be prepared to spend many
hours—perhapsoneormoredays—rewarmingbeforemovingaperson.Stovesandabund-
antfuelforheatingwatermustbeavailablesoheatingdevicescanberenewedastheycool.
Cardiopulmonary Resuscitation (CPR)
Cardiopulmonaryresuscitation(CPR)isessentialforsupportingprofoundlyhypotherm-
ic persons who have no effective blood circulation and can survive for only about an hour
without sustaining significant neurologic damage, particularly when evacuation is pro-
longed. However, the probability of success is limited, and risks to rescuers or other mem-
bers of the party cannot be justified. CPR should be initiated in the wilderness only by a
team of experienced individuals in a safe, relatively protected environment. If a hostile en-
vironment poses a major threat to the team, CPR should be postponed or abandoned en-
tirely.
Individuals with a detectable heartbeat, no matter how slow, should not receive CPR
or assisted ventilation because ventricular fibrillation would almost certainly result. Three
minutes or longer should be spent trying to detect a carotid pulse before assuming a
severely hypothermic person has no effective cardiac activity. The pulse rate may be as
slow as fifteen beats a minute.
Individuals whodonothaveadetectable heartbeat cannot beassumed tobeinventricu-
lar fibrillation. They could have weak but otherwise normal cardiac action, and starting
CPR would almost certainly cause them to go into ventricular fibrillation. A portable
ECG monitor to detect cardiac activity in persons with severe hypothermia may be neces-
sary, and rescue groups should carry such units. (In a wilderness environment, portable
ECG monitors cannot be relied upon for distinguishing abnormalities—such as asystole,