New Zealand Date/Time:
Sat, Mar 24, 2018, 5:45:34 AM

Hypothermia – what is it?

Hypothermia is when the body core becomes cold. While the temperature of the environment and the skin can fluctuate to a large degree, the inner body core temperature must remain constant. If the core temperature fluctuates up or down by as little as 1°, then major medical problems can result.

In cold air or water the skin and the external tissues become cooled rapidly and a person can feel very cold, however it takes 10-15 minutes before the core organs are affected. Shivering adjusts core temperature in mild cases, as does exercise and food intake.

Disorientation and loss of consciousness occur when the core temperature has dropped from the normal 37° to approximately 32°C-30°C. Death, caused by heart failure, can be the result of core temperature dropping below 30°C

When in the water hypothermia has a more indirect way of causing death. Long before the core temperature has dropped to below 30°C the loss of consciousness from hypothermia will have caused the victim to submerge and drown. Wearing a life jacket will prevent submersion and, in some cases, even provide protection from hypothermia itself.


Any kind of participation in activates in and around water, not just accidental entry into the water, increases the possibility of hypothermia. Beware of hypothermia when canoeing, fishing or swimming outdoors.

In all cases of “man overboard”, presume that hypothermia will be a possibility

  • Wear many layers of cloths, both in and out of the water. The more wind or waterproof clothing is the better
  • If setting out in cold, wet windy conditions be on the continual lookout for symptoms of exhaustion or hypothermia in others (refer “symptoms’)
  • The greatest amount of heat is lost through the top of the head and the backs of hands. Have a hat and pair of gloves to pit on if necessary.
  • Prevent excessive fatigue as it can contribute to hypothermia.
  • Eat or drink high-energy foods frequently.
  • If possible keep warm and dry. There are now also good quality materials, such as polypropylene, which keep you warm when wet, and are excellent for canoeing etc.

Survival in the water

Keep still

Swimming will make you feel warmer, however this is a false sensation. Energy is spent on activity rather than maintaining warmth so eventually the body core will become even colder.

Air is warmer than water

The body looses heat at a greater rate in water than in air of the same temperature, even though the chill factor may feel greater. If you find yourself in the water with floating objects, e.g., the upturned boat, then raise as much of the torso as possible out of the water.

Hypothermia first aid

Get the victim out of the water and into a warm and sheltered environment. First Aid for hypothermia varies greatly depending on the mildness or severity of the case. In many cases coldness and exhaustion are mistaken for mild hypothermia and vice versa. In both instances some warm nourishing food, warm clothes and mild exercise will increase core body temperature.

Carry low reading thermometer for use in suspected hypothermia cases.

Mild Cases

  • Warm, sweet drinks
  • Keep moving.
  • Warm clothes.
  • Mild heat source.

Moderate Cases

  • Same as above

If that does not work or the case is more severe:

  • Limit exercise.
  • Provide warm, sweet drinks only if victim is fully conscious.
  • Have victim checked by a doctor if possible.

Severe cases

  • The victim may behave irrationally and fight attempts to help. Ignore that and do what is necessary.
  • Time is a key factor. In severe cases of hypothermia attempts to rewarm the victim require expert knowledge. If help is available within an hour do not attempt to rewarm the victim yourself. This can be dangerous. Keep the victim stable and treat with extreme gentleness (Rough handling can cause cardiac arrest). Put them in the recovery position and elevate the feet. Send for expert help.
  • If help is more than an hour away then you have no choice but to attempt to rewarm the victim yourself. This must be done gently and slowly. Violent heat shocks, such as putting the person in a hot bath, can cause death.
  • Send for expert help.
  • No food or drink if there is any sign of unconsciousness.
  • Apply mild heat to the chest region only, e.g., warm hot water bottles wrapped in towels.
  • Do not attempt to rewarm limbs, e.g., feet, hands, arms or legs (This can cause the blood to flow to the limbs and away from the core where it is needed.)
  • Transport to hospital as soon as possible.

Critical cases

It is important that rewarming only happen in the field if expert help is more than an hour away.

Critical hypothermia can appear close to death.  Do not assume that someone is dead until the person is “warm and dead”. In other words continue to attempt to rewarm the victim even if they appear dead.

  • Send for expert help.
  • Handle with extreme care.
  • Tilt the head back to open the airway. Look, listen and feel for a pulse and breathing.
  • If there is any pulse, no matter how faint, do not give CPR. Keep a close watch on the pulse and breathing and be ready to give EAR or CPR if necessary.
  • Begin rewarming with mild external heat, e.g., wrapped warm hot water bottles, other people’s body heat.
  • Do not rewarm limbs
  • Exhale warm breath onto victims face so that they breathe in warm air.
  • Body core temperature lags behind skin temperature during rewarming. Keep the victim protected for an extended period, even after apparent full recovery or medical help arrives. It can take hours and even days to return to a normal, stable temperature. Do no re-expose to cold in that time.
  • Medical help is imperative and hospitalisation essential in severe and critical cases of hypothermia.