Frostbite

What is frostbite?

Frostbite causes fluid in skin cells and the tissues beneath the skin to freeze and damages blood vessels. This leads to the formation of blood clots which block the flow of blood and prevent oxygen from getting to the tissues. All cells need oxygen to function properly, as without it they die.

Symptoms

It's the extremities - the fingers, toes, face, ears and nose - that are affected most often because they easily lose heat when exposed.

Initially, the affected patches of skin become cold and white. They may tingle, which is known as a frost nip. Following this, as the damage becomes more severe, numbness develops together with blistering and pain.

Without treatment, the skin takes on a waxy feel and appears dark blue or black as the cells die. This death of the tissue is called gangrene.

Causes and risk factors

Frostbite can happen very quickly - within minutes - at any temperature below 0°C (32°F). The lower the temperature, the quicker the damage occurs.

Particularly vulnerable groups are older people and the young, whose body temperature control systems may not be as well developed or reliable.

Those with blood vessel damage caused by medical conditions, such as diabetes, or because of poor lifestyle habits such as smoking and high-fat diets, may also suffer frostbite more easily than others.

Drinking alcohol and taking certain medicines, such as beta blockers, also increases the likelihood of developing the condition.

Prevention

It's important to be aware that frostbite may occur and to take measures to ensure the skin is protected.

The extremities need protecting, as these areas are usually the first to be affected and are often forgotten about.

Always wear warm clothes that keep the extremities covered when outdoors. If someone is travelling to cold climates and isn't sure what clothing may be needed, it's a good idea to seek professional advice.

Treatment and recovery

When frostbite is suspected, the affected areas need to be warmed. However this should only be done when there's no risk of them freezing again, which could cause further and possibly irreversible damage.

Ideally, warming should be performed under medical supervision, but this isn't always possible.

It should be done slowly by immersing the areas in warm - not hot - water. As normal colour returns, they may appear red and swollen. Once this happens they can be removed from the water.

Never warm affected skin with direct heat, such as fire, because the lack of sensation in the skin caused by the frostbite may mean that person doesn’t feel the intensity of the heat and may remain unaware while the flesh burns.

In addition to warming, the affected areas need to be protected from further damage and infection. This can be achieved by applying a sterile dressing loosely to cover the skin.

Physiotherapy can help to improve circulation to the frostbitten area. Sometimes, however, the damage can't be repaired and amputation of the dead tissue is required to prevent further damage to surrounding healthy skin.

Frostbitten areas usually recover within six months, but people who have been affected may be left with permanent problems such as pain, stiffness and numbness.