COLD INJURIES - Medicine for Mountaineering and Other Wilderness Activities - page 395

RECOGNIZING HYPOTHERMIA
Hypothermia is usually divided into three levels: mild, moderate, and severe ( Table 26-2 ) .
By definition it begins when the body temperature falls to 95°F (35°C). Individuals who
are mildly hypothermic are not so incapacitated that they cannot stand or walk with assist-
ance. Usually their temperature is in the range of 90° to 92°F (32° to 33°C).
A person with moderate hypothermia has stopped shivering, is intellectually impaired,
andmaybeunabletowalk.Thebodytemperatureistypicallybelow90°F(32°C),although
the temperature at which such severe impairment appears varies significantly. A severely
hypothermic individual is unconscious and usually has a body temperature below 82°F
(28°C).
Temperature is not a practical basis for recognizing hypothermia in the wilderness be-
cause obtaining a temperature is so difficult. Profoundly hypothermic individuals usually
have their jaws clamped so tightly that oral measurements are impossible. Rescue person-
nel uniformly refuse to try rectal measurements, particularly in a threatening environment.
Such reluctance is probably fortunate because much of the time moving a person to take
such measurements could precipitate ventricular fibrillation (explained in the following
section).

Table 26-2. Stages Of Hypothermia

MILD HYPOTHERMIA

98°-95°F
37°-35°C

Sensation of chilliness; skin numbness; minor impairment in muscular per-
formance, particularly in fine movements with the hands; shivering begins

95°-93°F
35°-34°C

More obvious incoordination and weakness; stumbling; slow pace; mild
confusion and apathy

Gross incoordination with frequent stumbling, falling, and inability to use
hands; mental sluggishness with slow thought and speech; retrograde am-
nesia; uncontrollable shivering

93°-90°F
34°-32°C

MODERATE HYPOTHERMIA

90°-86°F
32°-30°C

Slowing and cessation of shivering; severe incoordination with stiffness
and inability to walk or stand; incoherence, confusion, irrationality

86°-82°F
30°-28°C

Severe muscular rigidity; semiconsciousness; dilatation of pupils; inappar-
ent heartbeat or respirations

SEVERE HYPOTHERMIA

Below 82°F
Below 28°C

Unconsciousness; eventually death due to cessation of heart action at tem-
peratures of 77°F (25°C) or below