Frostbite is a condition where the skin and underlying tissue actually freeze. It occurs when body parts, usually the extremities such as the toes, feet, fingers, ears, nose and cheeks are exposed to extremely cold conditions. The condition rarely occurs in fit and healthy individuals in still air temperature above minus 10 degrees Celsius but may do so at higher temperatures in high winds due to the wind chill effect.
Certain processes taking place in the body, in response to exposure to extreme cold, cause frostbite.
* Firstly, blood flow to the skin and extremities is slowed down as blood vessels constrict (narrow). This occurs so blood can be redirected to the vital organs to keep the body alive and warm. Ice crystals form in the tissues, the blood vessel walls are damaged and the cells start to break down.
* Secondly, with continued exposure to the cold, as the extremities get colder and colder, the blood vessels dilate (widen) for a brief period before constricting again. This happens because the body is trying to preserve as much function in the extremities as possible. However, the blood returning to the extremities leaks out through the leaky blood vessels. This causes further damage to the tissues.
Certain groups of people are at greater risk of getting frostbite than others, these include:
* Winter and high-altitude athletes, e.g. mountaineers and skiers
* Individuals stranded in extreme cold weather conditions
* Soldiers, cold weather rescuers and labourers working in cold environments
* Homeless people
* Very young and the very old people
* People with decreased blood flow to the extremities such as those with peripheral vascular disease or diabetes
* Those taking certain drugs that constrict blood vessels, e.g. nicotine (smoking) or beta blockers
The signs and symptoms of frostbite include coldness, firmness, stinging, burning, numbness, clumsiness, pain, throbbing, excessive sweating, pallor or blue skin discolouration, rotting skin and gangrene. Frostbite has been classified under the following categories that relate to the degree of injury.
* First-degree frostbite
This is also called frost nip and occurs in people who live in very cold climates or do a lot of outdoor activity in winter. It involves the top layer of skin (epidermis) and presents as numbed skin that has turned white in colour. The skin may feel stiff to touch, but the tissue underneath is still warm and soft. Blistering, infection or scarring seldom occurs if frost nip is treated promptly.
* Second-degree frostbite
This is superficial frostbite and presents as white or blue skin that feels hard and frozen. Blisters usually form within 24 hours of injury and are filled with clear or milky fluid. The tissue underneath is still intact but medical treatment is required to prevent further damage.
* Third-degree frostbite
Deep frostbite appears as white, blotchy and/or blue skin. The underlying skin tissue is damaged and feels hard and cold to touch. Blood-filled blisters form black thick scabs over a matter of weeks. Proper medical treatment by personnel trained to deal with severe frostbite is required to help prevent severe or permanent injury. Amputation may be required to prevent severe infection.
*Fourth-degree frostbite is where full-thickness damage affects muscles, tendons, and bone, with resultant tissue loss.
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