Hypothermia and Frostbite
In this condition factsheet:
The Facts on Hypothermia and Frostbite
Hypothermia occurs when you have abnormally low body temperature. Normal body temperature is around 37°C (98.6°F), as measured by mouth. Hypothermia is defined as a drop in body temperature below 35°C (95°F). Young babies (because they have a greater surface area to body weight ratio) and seniors are the most vulnerable to developing hypothermia.
When the body becomes very cold, all physiological systems begin to slow down - eventually to the point that threatens survival. In some rare cases, though, hypothermia can save lives. There are cases where children who have fallen into freezing water were successfully revived even when there was no heartbeat. Their below-normal temperature slowed down their brain function and caused their bodies to use less oxygen.
Frostbite happens when a part of the body actually freezes. Mild frostbite doesn't leave lasting damage, but severe frostbite does cause permanent damage and may even require amputation of a body part.
Smokers and people with diabetes and other circulatory problems have a higher risk of developing frostbite.
Causes of Hypothermia and Frostbite
Hypothermia can occur in a number of situations, most often where extremely cold weather is a factor. You're at risk if you're not adequately dressed for the cold, if you're outside longer than you'd planned or you can't move, if you fall into near-freezing water, or if your clothing gets wet.
Every winter, some seniors die from hypothermia in their own homes because they can't pay for adequate heating or their heating systems break down and they can't get repairs done.
Hypothermia can also happen in the summer. Many lakes never get very warm and swimmers who stay in cold water for too long can become hypothermic. These cases often involve fishermen who have fallen into the water.
Frostbite is caused when body parts, usually fingers, toes, noses, and ears, are frozen. Extreme cold, a wind-chill factor, altitude, and lack of proper protective clothing all contribute to quicker freezing of the skin. People taking beta-blocker medications such as propranolol* and metoprolol may also have a higher risk of frostbite.
Symptoms and Complications of Hypothermia and Frostbite
Hypothermia can come on very slowly, making it difficult to notice that it's happening. When your body is cold, you try to protect yourself by shivering. When hypothermia sets in, the shivering stops as your body is now trying to conserve energy. This is one of the first warning signs of hypothermia. You might also begin to feel clumsy and disoriented as your body temperature drops. Other signs include forgetfulness, drowsiness, slurred speech, slow or irregular heartbeat, and shallow breathing.
One complication of hypothermia is that the heart becomes very sensitive and can be easily jolted into an irregular rhythm. If you try to rescue someone with hypothermia, you need to be as gentle as possible to prevent any sudden movements. As well, emergency personnel will monitor the heart during the re-warming process to watch for any irregularities.
How fast the signs of frostbite develop depends on the air temperature, wind-chill factor, and how well the affected body part is protected. It's possible to get frostbite within minutes during extremely cold conditions.
Mild frostbite (frostnip) makes the skin look white or waxy but the colour returns once the skin is warm again. Once thawed, the skin might turn red and it could take a while for the redness to go away.
Severe frostbite begins with white or waxy-looking skin, but the colour becomes grey or bluish as the damage progresses. The cold feeling disappears and is replaced with numbness, and blisters might form. At this point, it's very easy to cause other damage besides the actual freezing. For example, because you might have lost feeling in a foot that is frostbitten, you might not feel blisters forming and breaking. A frozen finger could break easily in a fall, and skin can burn very easily if it's not warmed up properly.
As a frozen body part warms up, the area may swell, itch, burn, and be extremely painful. Extreme frostbite will turn the skin black, and gangrene may develop, in which case amputation may be needed.