COLD INJURIES - Medicine for Mountaineering and Other Wilderness Activities - page 397

pears. This sign is usually easy to recognize and serves as a clear, unmistakable warning
that the group must stop and begin rewarming the affected individual or individuals. Once
shivering has ceased, individuals so affected can no longer rewarm themselves and an ex-
ternal heat source is required. As body temperature drops further, muscular incoordination
becomes so severe that the individual cannot walk without assistance and eventually be-
comes unable to stand without support.
Intellectual impairment is greater, but the impairment may be subtle. A common and
important sign of severe hypothermia is neglect or carelessness about protection from the
cold. Coats are left unzipped; hoods are not pulled up; caps or mittens are not worn. Sleep-
ing bags or blankets are not snug around the head; fires are neglected. Sometimes severely
hypothermic individuals urinate in their clothing.
Individuals who seemed to be acting quite sensibly have made gross errors in judgment
that have caused problems for an entire group. A typical pattern is the individual who ap-
pears to be capable of cooperating with other members of the group but does not.
Severe Hypothermia
Severe hypothermia has been defined as a temperature below 82°F (28°C). Eventually
confusion and irrationality progress to incoherence, semiconsciousness, and finally total
unconsciousness and a failure to respond to any stimuli. At this temperature, death is im-
minent. Rough handling can precipitate ventricular fibrillation, so these individuals must
behandledasgentlyaspossible.Atatemperaturebelow77°F(25°C)theheartmaygointo
ventricular fibrillation spontaneously. When the temperature drops into the low 70s, heart
activity usually ceases, either as the result of ventricular fibrillation or asystole.
As an individual begins to lose consciousness, a sensation of extreme warmth may de-
velop, and if unattended, the person may actually remove clothing or climb out of a sleep-
ing bag. Such bizarre behavior is not uncommon, and its occurrence in urban surroundings
has aroused suspicion that the person has been assaulted, particularly when the person has
been female. (Sometimes the individual's clothing has been neatly folded, an unlikely oc-
currenceduringanassault.)Althoughthereasonforsuchbehaviorisnotreallyknown,one
proposed mechanism is dilatation of the blood vessels in the skin, producing a sensation of
warmth that prompts the semicomatose person to disrobe or climb out of a sleeping bag.
The diversion of blood flow from the brain to the skin by the cutaneous vasodilatation is
probably the last straw that drops the person into complete unconsciousness.
As a severely hypothermic individual's condition deteriorates, body functions slow
drastically. A comatose person's breathing may be so slow and shallow that it appears ab-
sent.Theheartratealsoslowsdramatically andcanbecomesoweakthatitcannotbepalp-
ated.
Unquestionably, a number of individuals with severe hypothermia who were actually
stillalivehavebeenpronounceddeadanddeniedmedicalassistance.Inthewilderness,few