Generality
Freezing (in English frostbite ) is a tissue damage caused by prolonged exposure to extreme cold. The initial phases of the phenomenon are superficial and do not cause permanent injuries; severe freezing, however, requires medical attention, as it can destroy the skin tissues and underlying blood vessels. The effects can be temporary (superficial freezing) or permanent, if complications occur, such as damage to muscles, bones and nerves, infections and gangrene.
Causes
At temperatures equal to or below 0 ° C, the blood vessels under the skin begin to shrink (vasoconstriction) and the blood is diverted from the extremities to the vital organs, through the action of the glomic bodies (the glom is a component of the dermis, involved in the regulation of body temperature). The same reaction can be induced by exposure to strong winds and severe weather conditions (eg snow storms). Vasoconstriction helps to maintain body temperature and prevent heat loss.
When the body is exposed to cold for long periods of time, this protective strategy can reduce blood flow to dangerously low levels in some areas. While the blood is redirected away from the extremities of the body, the liquids present in the tissues freeze and form ice crystals, which can cause serious damage to the area. If blood flow cannot be restored, it deprives the oxygen cells, eventually leading to tissue death (gangrene).
Degrees of freezing
First degree freezing
The initial stages of freezing affect only the surface of the skin and the affected area is usually not permanently damaged. On the onset, numbness, tingling, itching and pain occur in the affected area. The skin becomes cold, numb and pale, as a result of reduced blood circulation. Mild freezing forms can be resolved by transferring the patient to a warm place with first aid measures.
Second degree freezing
If exposure to low temperatures continues, freezing extends to the epidermis and dermis, but does not yet involve the deep tissues. The skin becomes blue-white and begins to harden to the touch. Medical intervention is necessary to ensure that no permanent damage occurs. With heating, the skin becomes red, swollen, itchy and painful and blisters or blisters appear after 1-2 days. Second degree injuries heal in a month, but the area can become permanently numb.
Third and fourth degree freezing
Freezing becomes more and more serious and involves further damage, involving muscles, tendons, blood vessels and nerves. In fact, an inflammatory process is established by intervention of the immune cells, which temporarily compromises, and in severe cases, definitively, the functionality of the area involved. At the thaw of the skin, the bladders fill with blood and turn into thick purple-black crusts, while damage to nerve endings can cause permanent loss of sensitivity. Fourth degree lesions occur when frozen tissues begin to necrotize. Extreme freezing can determine the need to resort to surgery or amputation to remove necrotic tissue.
Symptoms
To learn more: Symptoms Freezing
The symptoms of freezing are manifold, but the common warning signs include numbness, burning and pain in the area. If exposure to cold continues, tingling may be replaced by a loss of sensitivity to touch; with the aggravation of freezing, the pain begins to fade, until it disappears.
The severity of the phenomenon depends on how much the ambient temperature is below 0 ° C and on the duration of the exposure.
Other typical signs of freezing include:
- Decreased oxygen at the cellular level (anoxia);
- Edema;
- Bruising;
- Blistering or blistering;
- Necrosis of the tissue.
The parts of the body most susceptible to freezing, as they are most exposed, are: nose, ear lobes, fingers and toes. In mild cases, complete recovery is possible with rapid medical intervention. The greatest consequences occur in tissues that freeze, thaw and re-freeze.
Risk factors
Risk factors for freezing include diseases that cause vascular damage and circulation problems, such as diabetes and Raynaud's phenomenon. Freezing is not a common problem, but some people who practice winter and high-altitude sports (such as mountaineers and skiers) or those who work in extreme weather conditions for a long time (sailors and rescuers) should take appropriate precautions. In these contexts, the same factors that can lead to freezing (cold temperatures, inadequate clothing, wet clothes, freezing wind, etc.) can contribute to hypothermia.
Treatment
Treatment of freezing damage depends on the severity of the condition. If medical assistance is not immediately available, it is useful to look for a stable and warm environment. It is important to remember that excessive movement of frozen tissue can cause further injury: friction can destroy already damaged skin and increase the risk of infection. For this reason, rubbing or applying physical force in an attempt to heat the affected area can be harmful.
Heating can be carried out in the following ways:
- Passive heating: involves the use of body heat or environmental temperature. Passive heating includes wrapping in blankets to protect frozen parts or transfer to warmer environments. The patient must not use direct heat sources, such as stoves, fireplaces or bonfires, as these can cause burns (facilitated by the reduced or absent sensitivity of the area considered). Replacing wet clothes with soft, dry clothes can stop further heat loss.
- Active heating: the direct administration of heat to a person requires more equipment and may be difficult to perform in a non-hospital environment. Active heating is achieved by immersing the injured tissue in a water bath, at a temperature of 40-42 ° C, for about an hour. The heating of peripheral tissues can dilate blood vessels and restore circulation to the area. However, the procedure is intensely painful and may increase the risk of cardiac arrhythmias.
Surgery
The debridement and amputation of necrotic tissue are usually delayed procedures, with exceptions for signs of infection or gas gangrene. Thrombolytic drugs, which act as tissue plasminogen (tPA) activators, can be administered to try to reduce the need for amputation. However, these agents can cause serious bleeding and are generally used only in particular situations, within 24 hours of exposure.
Recovery and long-term effects
If freezing has not damaged blood vessels, a complete recovery is possible. Otherwise, injuries can be permanent. A number of long-term effects can follow frostbite: transient or permanent changes in sensitivity, paresthesia, persistent pain and arthritis in the affected area of the body.
