Hypothermia
Hypothermia occurs when the body's internal temperature drops below normal. It can be fatal and is claimed to be the number one killer of outdoor recreationalists. But others are also at risk.
One of the greatest threats to people participating in outdoor sports, such as walking, mountaineering or sailing, is hypothermia - when the internal temperature of the body drops below normal as a result of being in a cold environment.
But small babies, the elderly and people with severe illness can also easily become hypothermic, even indoors, and each year there are many deaths as a result - deaths which get far less attention than the loss of a famous climber on a mountain.
The government now offers extra support for some of the vulnerable in the form of winter fuel payments, to help keep their homes warm. You can check out whether you are eligible at the Department of Social Security.
But there are plenty of other things that can help prevent hypothermia. And if you're a sportsperson at risk, knowing what hypothermia is, and how to manage it, could one day save your life.
Preventing hypothermia:
- stay indoors as much as possible and limit exposure to the cold
- eat regularly, with plenty of carbohydrates (the body needs a reliable and constant energy supply to generate heat)
- keep as active as possible (helps to generate warmth)
- avoid alcohol - it causes dilation of peripheral blood vessels so increasing heat loss
- avoid caffeine - it's a diuretic and increases the risk of dehydration, which aggravates heat loss
- avoid nicotine - it constricts the blood vessels and increases the risk of cold damage such as frostbite
- wear multiple thin layers of clothing rather than one thick jumper, which helps to trap heat
- if you go outside, always wear a hat (it can prevent as much as 20 per cent of heat loss) and gloves
- people who work in cold environments, such as in freezer stores, may also be at risk. Children need particular care and even animals are vulnerable.
Spotting hypothermia
Hypothermia is classified as a temperature below 35.5°C (96°F). A memorable tip is to watch out for the 'umbles': stumbles, mumbles, fumbles, and grumbles. These are symptoms that show a gradual reduction in coordination of muscles and movement, and a falling level of consciousness.
This is how symptoms progress as the person's temperature drops:
1. Initially - involuntary shivering, loss of complex motor skills (but still able to walk and talk), shut-down of the blood vessels in the hands and feet.
2. As temperature falls below 35°C (95°F) - violent shivering, impaired consciousness, loss of fine motor coordination, especially in the hands, slurred speech, illogical behaviour, loss of emotional cognition - an 'I don't care' attitude.
3. As core temperature falls below 34°C (92°F) , the effects become life threatening - shivering become intermittent and then stops, the person curls into the fetal position, muscles become rigid, pupils dilate, pulse rate drops.
4. By 30°C (86°F) the person looks dead. Although still alive, they're in a state known as the metabolic icebox - breathing becomes shallow and erratic, consciousness is lost, the heart becomes vulnerable to deadly arrhythmias.
Shivering is an important guide
Shivering can increase heat production by up to 500 per cent
Shivering is one of several symptoms that can be used to assess hypothermia. Shivering can increase heat production by up to 500 per cent. However, you're only able to shiver for a few hours because the action depletes muscle stores of glucose and fatigue sets in. If the person is able to stop themselves shivering, the hypothermia is only mild. But if it can't be stopped voluntarily, the person has moderate to severe hypothermia.
Another quick test is to test higher brain functioning by asking the person to count backwards from 100 in nines. This sort of cerebral ability is soon lost as temperature falls. A sign of severe hypothermia is loss of the pulse at the wrist (as the circulation shuts down).
Treatment
The basic principles are to stop heat loss and preserve the heat the person has, and provide body fuel to generate more heat. If a person is shivering, they can warm themselves at a rate of 2°C (35.6°F) an hour.
Therefore, put on additional layers of clothing, or replace wet clothes with dry. Get them moving to increase their activity, and ensure their surroundings are as warm and still as possible. Provide food, initially as hot liquids. Carbohydrates provide a rapid source of energy while fats can provide a prolonged source of fuel. Add warmth with a fire or from body to body contact.
Severe hypothermia needs urgent medical attention.
Hypothermia risks of outdoor sports
There are some particular risks associated with outdoor sports. The risks are as follows:
- When the weather gets cold and windy - windy conditions speed heat loss known as wind chill.
- Failing to wear suitable clothing and equipment.
- Getting wet - water conducts heat away from the body 25 times faster than air. Staying dry can mean staying alive. If you are in water, knowing what to do could save your life - for example, swimming increases heat loss by up to 50 per cent and isn't recommended if you're more than one kilometre away from shore.
Fatigue and exhaustion.
Dehydration: fluid levels, fluid loss and heat loss are interconnected. As body moisture is lost, the volume of the circulation is reduced, which can lead to dehydration and makes the body more susceptible to hypothermia and other cold injuries.
Inadequate food intake.
A lack of knowledge of hypothermia and its risks - alcohol causes vasodilation, which aggravates heat loss.
