HYPOTHERMIA
By Dr. Clare O'Leary and Pat Falvey.

Hypothermia occurs when the central core (brain, heart, deep vessels) body temperature falls below 35°c.

Hypothermia is classified as:

• Mild - core temperature 32-35°c
• Severe - core temperature below 32°c

Injured climbers may suffer acute hypothermia (occurs over minutes or hours), but more common is subacute hypothermia. The rate of onset is variable and contributing factors will include:

• Severe weather conditions
• Inadequate clothing
• Insufficient food
• Exhaustion

The body reacts initially by vasoconstriction (constriction of the blood vessels) and increases heat production by exercise and shivering; when exhaustion supervenes, core temperature falls.
 
CLINICAL FEATURES OF MILD HYPOTHERMIA

• Feeling cold
• Loss of interest in activities (except keeping warm)
• Poor coordination
• Stumbling
• Attacks of violent shivering
 
CLINICAL FEATURES OF SEVERE HYPOTHERMIA

• Altered mental function
• Slowed thinking
• Difficulty making decisions / poor decisions
• Deterioration of memory
• Strong desire to sleep
• Collapse of will to survive
• Progressive unresponsiveness/slurred speech/staggering
• Coma
 
The temperature at which unconsciousness occurs is variable (27-33°c) and depends on the rate of cooling. When the temperature drops to below 30°c, ventricular fibrillation (irregular fast heartbeat that causes the heart to stop pumping) may supervene.
 
MANAGEMENT: MILD HYPOTHERMIA

• Prevent further heat loss
• Stop exercise
• Place patient in sheltered area
• If possible, replace wet clothing with dry; otherwise, wring out wet
--clothing and put back on
• Cover the head (large amounts of heat lost through the head)
• Give warm fluids; never alcohol
• Add external heat if possible (eg. put the patient in a sleeping bag with --another person)
 
MANAGEMENT: SEVERE HYPOTHERMIA

• If possible, evacuate
• Aluminium foil blankets/suits
• If evacuation delayed, rewarm slowly
• Treat as gently as possible to avoid triggering ventricular fibrillation
• If cardiac arrest occurs, begin resuscitation
• It is very difficult to confirm death as long as the patient is hypothermic
 
CAUTION

Every high mountain trauma patient should be suspected of having hypothermia

Every hypothermic patient should be suspect of having other injuries