Hypothermia occurs when the body temperature is below 35°C. This can develop with prolonged exposure to temperatures under 10°C, or after prolonged immersion in cold water of less than 20°C.
A person with hypothermia may not be aware of their need for medical attention.
A body temperature below 32°C is life threatening.
What is hypothermia?
- Hypothermia develops when the body temperature drops below 35°C. The normal human body temperature is around 37°C.
- As the body temperature drops below 32°C, hypothermia becomes severe and life threatening.
What are the symptoms?
- The first signs usually include feeling cold and uncontrollable shivering. If the person progresses into severe hypothermia, shivering usually stops.
- The person may feel exhausted and their skin may be cool and pale.
- As hypothermia advances, other symptoms include, fumbling hands, unsteady gait, slurred speech, confusion and drowsiness.
- Hypothermia can progress slowly and affected people may not be aware they need medical help.
- Symptoms of severe hypothermia include slowing of the heart rate and breathing, dilated pupils, and coma. The person may appear dead.
- With no treatment the condition is likely to lead to death.
How do you develop hypothermia?
- Hypothermia can develop with prolonged exposure to temperatures under 10°C, or after prolonged immersion in cold water of temperatures of less than 20°C..
- In colder conditions or when there is wind chill (the felt air temperature due to wind) it can occur within a shorter exposure.
- A person can be at greater risk of hypothermia as a result of some medical conditions.
Who is at risk?
Hypothermia can affect anyone, those at higher risk include:
- people over 75 years.
- babies and young children.
- people with poor circulation or diabetes.
- people with chronic physical or mental disabilities.
- people with underlying infection.
- people who are very thin and have low body fat.
- people who work outdoors.
- people who are homeless.
- people who are wet from any cause.
How is it prevented?
- Listen to the weather forecast.
- Plan ahead: schedule warm-up breaks for outdoor workers, hold recess and breaks inside, limit the amount of time you spend outdoors.
- Dress warmly in layers (wind-resistant jacket, mittens, boots, hat and scarf).
- Stay dry (wet clothing chills the body rapidly).
- Get out of the cold as soon as you can if you start feeling cold.
- Alcohol, cigarettes, caffeine and certain medications will increase your susceptibility to cold.
- Hypothermia can occur in the home: ensure there is adequate heating, especially for elderly people. Also, elderly people living on their own should consider wearing a personal emergency response system (PERS) as they are at risk of falls and hypothermia could develop if help is not at hand. The Council on the Ageing (NSW) provides information about PERS via their factsheet Personal Alarms.
For parents and carers of children
- Young children and babies are at high risk from extreme cold and can develop hypothermia very quickly as their body size is so small. It is important to cover their head if they are out in cold weather.
- Children can become colder much quicker than adults because they have less muscle mass.
- Limit exposure to prolonged or extreme cold weather.
How is it diagnosed?
- The diagnosis is generally made based on the person's symptoms and the condition in which the person became unwell or was found. However, if the diagnosis is not obvious, it can be made by measuring the core body temperature with a special low-reading thermometer (general medical thermometers do not measure temperatures below 32-34°C).
- Mild hypothermia: 32-35°C.
- Severe hypothermia: below 32°C.
How is it treated?
- Get medical attention (call 000).
- Move the person out of the cold, remove wet clothing.
- Warm the person at the centre of the body (chest, neck, head, groin).
- Do not use direct heat; use warm blankets, towels, wrapped warm water bottles or skin to skin contact.
- Do not massage or rub the person.
- Keep the person still.
- If a person is awake, warm drinks can help.
- Do not give alcoholic beverages.
- If the person appears dead, CPR should be given whilst the person is being warmed - never assume the person is dead!
In NSW, call 1300 066 055 to talk to your local Public Health Unit.