Hypothermia can kill at an amazing pace when cold temperatures and strong winds cause the body to lose heat quickly. Shivering starts first in order to produce body heat from the rapid muscular shaking. When the body’s temperature dropsto or below 35 deg C/95 deg F, dizziness and disorientation kick in, then the shivering stops. The body now only maintains heat around the vital organs – brain, heart and lungs, and shuts down blood circulation to the arms and legs. Heart rate becomes slow, intermittent and weak, and the blood vessels widen. This makes a person feel hot and want to remove all their clothes before they finally slip into unconsciousness. Ultimately, the heart stops. Stories are told of climbers being found naked and dead up on a mountain, with their clothes folded neatly a short distance away. This is because the person becomes confused and hot. Their brain tries to bring order to the scary and unfamiliar situation, although this can be potentially lethal.
The risk of hypothermia is significantly higher when:
- Temperatures are below freezing, although anything which is below body temperature (98.6°F/37C) can explain hypothermia, especially in old people.
- Climbers are wearing inappropriate clothing or using ineffectual equipment.
- Climbers are either wet, tired, dehydrated or suffering from malnutrition.
- Climbers are ignorant of hypothermia.
- Alcohol is consumed, because alcohol makes blood vessels dilate, providing a lager surface area through which heat can be lost.
”As with frostbite it is easier to prevent hypothermia than it is to cure it.
Here are some valuable tips:”
- Eat properly with plenty of carbohydrates and fats for energy and warmth.
- Drink plenty. If a person doesn’t get up in the night at least once to urinate then they are not drinking enough. Urine should be a pale yellow, straw-like colour, not dark.
- Get enough sleep. Climbing mountains is gruelling work and cannot be done on only four hours sleep. Being well rested will make you feel energized and positive about the day’s climb.
- Remove any wet clothes immediately. They cause accelerated heat loss and impair movement.
- Insulate well, particularly the head and neck as these are the areas which lose the most heat the quickest. Good materials are Goretex and Thinsulate.
It is also useful to have knowledge of the symptoms. If you suspect a person to have hypothermia then you can react and cut the time they spend in that environment, which could save their life. Here are the signs, in order of occurrence:
- Core temperature between normal and 35.5°C/96°F
- Involuntary shivering
- Inability to do things requiring motor skills e.g. skiing, but can still walk and talk
- Core temperature between 35°C/95°F and 33°C/93°F
- Dazed state of mind
- Loss of general motor control e.g. untying boot laces
- Slurred speech
- Aggressive shivering
- Taking off clothes because they believe they are cold
- Ambivalent behaviour, especially in relation to survival
- Core temperature between 33°C/92°F and 30°C/86°F
- Pale skin
- Dilated pupils
- Waves of aggressive shivering, followed by pauses. The pauses get longer until shivering finally stops because the body realises that it is not creating enough heat and chooses to retain the energy instead.
- Flexibility and movement is reduced because of a lack of blood flow and a build up of lactic acid and carbon dioxide
- Person ceases movement and curls up in the foetal position to conserve heat
- Slow, intermittent, weak pulse
- Body goes into hibernation and person appears dead although they may actually still be alive
- Core temperature under 30°C/86°F
- Breathing becomes erratic and shallow
- Person is only semi conscious
- Heart stops
If you think you have spotted any of these signs then there are practical ways of assessing the stages of hypothermia, as detailed below:
- Ask the person to stop shivering. If they can then hypothermia is most likely mild.
- Ask they person a mathematical question. If they can do it then hypothermia is most likely mild.
- If you can’t find a pulse at the person’s wrist then this can be a sign of a core temperature of less than 32°C/90°F, indicating severe hypothermia.
- If the person is in a foetal position try to open their arms. If they curl back then the person is probably still alive, because dead muscles will not contract.
In the event of hypothermia, the first option is to seek professional medical help. Understandably 5500m up a mountain this may not be immediately possible, so practical re-warming techniques are very important. The idea behind re-warming is to preserve any heat they have and replenish what has been lost. Here are a few techniques:
- Inhalation re-warming. This warms up the body’s critical core, along with the head and neck. More importantly it warms the hypothalamus, which is situated at the bottom of the brainstem and plays a vital part in the central nervous system. The hypothalamus regulates the body’s internal temperature and controls breathing and the circulatory system. Inhalation re-warming involves the individual breathing in warm (about 45°C/122°F), moist air. This can be done with professional equipment, or by breathing directly above, but not covering the individual’s mouth and nostrils. It sends vital heat directly to the areas it is needed most, and so can be very effective, especially in raising an individual’s level of consciousness. It is also a good method as it reduces respiratory heat loss, which can account for up to 30% of the body’s
total heat loss. This is particularly important in mountain situations where the surrounding air is likely to be below freezing.
- Keep the individual’s movement to a minimum. Making the muscles work at this stage is likely to send cold blood from the legs and arms into the central circulatory system. This will cause the core temperature to fall even more, which could be fatal as when the heart is cold its natural rhythm is disturbed. This is called afterdrop.
- Add dry clothing layers.
- Increase movement.
- Get out of the hypothermic conditions.
- Keep well hydrated and ensure proper levels of nutrition.
- Drink something hot.
- Eat something sugary, something with carbohydrates and something with fats in, to gain immediate, slow release and stored energy, espectively.
- Avoid alcohol, which increases heat loss, tea/coffee which are diuretics and increase dehydration, and tobacco which reduces the blood flow to extremities.
- Light a fire.
- Use another person’s body heat by getting into a sleeping bag with someone.
- Hypothermia wrap. This works on the principle that a person can regenerate their heat better than any external heat source can. Shivering alone can produce 2°C per hour. The individual must be dry and in a dry place because any moisture they come into contact with will result in further heat loss. Lay out a selection of sleeping bags, blankets and at least one aluminium blanket directly on top of each other on the floor and position the person on top, face up. Fold securely as below.
- Warm sugar water. Give the person a diluted mix of sugar and warm water every 15 minutes. This allows direct absorption when the person cannot digest real food. It provides the energy needed so the person can re-warm themselves.
- Urinate. A full bladder conducts heat away from the body and so urinating frequently will solve this. The person may need to be assisted.
- Apply heat to the major arteries in the neck, armpit, crotch and palms, using hot water bottles or warm towels. A rock can be heated up on a fire and used if necessary; they generally retain heat quite well.