Frostbite is localized tissue injury that occurs because of exposure to freezing or near freezing temperatures. Frostnip is a milder cold injury that does not cause tissue loss.
Description
In North America, frostbite is largely confined to Alaska, Canada, and the northern states. In recent years, there has been a substantial decline in the number of cases. This is probably for several reasons, including better winter clothing and footwear and greater public understanding of how to avoid cold-weather dangers.
At the same time, the nature of the at-risk population has changed. Rising numbers of homeless people have made frostbite an urban as well as a rural public health concern. The growing popularity of outdoor winter activities has also expanded the at-risk population.
    |
Causes & symptoms
Frostbite
Skin exposed to temperatures a little below the freezing mark can take hours to freeze, but very cold skin can freeze in minutes or seconds. Air temperature, wind speed, and moisture all affect how cold the skin becomes. A strong wind can lower skin temperature considerably by dispersing the thin protective layer of warm air that surrounds our bodies. Wet clothing readily draws heat away from the skin. The evaporation of moisture on the skin also produces cooling. For these reasons, wet skin or clothing on a windy day can lead to frostbite even if the air temperature is above the freezing mark.
The extent of permanent injury, however, is determined more by the length of time the skin is frozen than by how cold the skin and the underlying tissues become. Thus, homeless people and others whose self-preservation instincts may be clouded by alcohol or psychiatric illness face a greater risk of frostbite-related amputation.
They are more likely to stay out in the cold when prudence dictates seeking shelter or medical attention. Alcohol also affects blood circulation in the extremities in a way that can increase the severity of injury, as does smoking. A review of 125 Saskatchewan frostbite cases found a tie to alcohol in 46% and to psychiatric illness in 17%. Driving in poor weather can also be dangerous: vehicular failure was a predisposing factor in 15% of the Saskatchewan cases.
Frostbite is classified by degree of injury (first, second, third, or fourth), or simply divided into two types, superficial (corresponding to first- or second-degree injury and deep (corresponding to third- or fourth-degree injury). Most frostbite injuries affect the feet or hands. The remaining 10% of cases typically involve the ears, nose, cheeks, or penis.
Once frostbite sets in, the affected part begins to feel cold and, usually, numb; this is followed by a feeling of clumsiness. The skin turns white or yellowish. Many patients experience severe pain in the affected part during rewarming treatment and an intense throbbing pain that arises two or three days later and can last days or weeks. As the skin begins to thaw during treatment, edema often occurs, causing swelling in the area. In second- and higher-degree frostbite, blisters appear.
Third-degree cases produce deep, blood-filled blisters and, during the second week, a hard black eschar (scab). Fourth-degree frostbite penetrates below the skin to the muscles, tendons, nerves, and bones. In severe cases of frostbite, the dead tissue can mummify and drop off. Affected areas are also more prone to infection.
Frostnip
Like frostbite, frostnip is associated with ice crystal formation in the tissues, but no tissue destruction occurs and the crystals dissolve as soon as the skin is warmed. Frostnip affects areas such as the earlobes, cheeks, nose, fingers, and toes. The skin turns pale and numb or tingly until warming begins.
Diagnosis
Frostbite diagnosis relies on a physical examination and may also include conventional radiography (x rays), angiography (x-ray examination of the blood vessels using an injected dye to provide contrast), thermography (use of a heat-sensitive device for measuring blood flow), and other techniques for predicting the course of injury and identifying tissue that requires surgical removal. During the initial treatment period, however, severity is difficult to judge. Diagnostic tests only become useful 3-5 days after rewarming, once the blood vessels have stabilized.
Treatment
Mechanical treatment
Frostnipped fingers are helped by blowing warm air on them or holding them under one’s armpits. Other frostnipped areas can be covered with warm hands. The injured areas should never be rubbed.
By contrast, emergency medical help should always be sought whenever frostbite is suspected. While waiting for help to arrive, one should, if possible, remove wet or tight clothing and put on dry, loose clothing or wraps. A splint and padding are used to protect the injured area. Rubbing the area with snow or anything else is dangerous.
      |
The key to prehospital treatment is to avoid partial thawing and refreezing, which releases more mediators of inflammation and makes the injury substantially worse. For this reason, the affected part must be kept away from heat sources such as campfires and car heaters. Experts advise rewarming in the field only when emergency help will take more than two hours to arrive and refreezing can be prevented.
Because the outcome of a frostbite injury cannot be predicted at first, all hospital treatment follows the same route. Treatment begins by rewarming the affected part for 15-30 minutes in water at a temperature of 104-108°F (40-42.2°C). This rapid rewarming halts ice crystal formation and dilates narrowed blood vessels.
Aloe vera (which acts against inflammatory mediators) is applied to the affected part, which is then splinted, elevated, and wrapped in a dressing. Milky blisters are debrided (cleaned by removing foreign material), and hemorrhagic (blood-filled) blisters are simply covered with aloe vera.
Hydrotherapy
Alternative practitioners suggest several kinds of treatment to speed recovery from frostbite after leaving the hospital. Bathing the affected part in warm water or using contrast hydrotherapy can enhance circulation. Contrast hydrotherapy involves a series of hot and cold water applications.
A hot compress (as hot as the patient can stand) is applied to the affected area for three minutes followed by an ice-cold compress for 30 seconds. These applications are repeated three times each, ending with the cold compress. For patients who have been hospitalized with frostbite, hydrotherapy should only be performed after checking with a physician to ensure it is done correctly and does not aggravate the condition.
Homeopathy
Homeopathic Hypericum (Hypericum perforatum) is recommended when nerve endings are affected (especially in the fingers and toes) and Arnica (Arnica montana) is prescribed for shock and if there is accompanying blunt trauma to the frostbitten area.
Nutritional supplements
Cayenne pepper (Capsicum frutescens) can enhance circulation and relieve pain. Drinking hot ginger (Zingiber officinale) tea also aids circulation.
Other complementary therapies
Other possible approaches include acupuncture to avoid permanent nerve damage and oxygen therapy.
Allopathic treatment
In addition to the necessary rewarming and debridement described above, a tetanus shot and antibiotics may be used to prevent infection. The patient is given ibuprofen to combat inflammation. Narcotics are needed in most cases to reduce the excruciating pain that occurs as sensation returns during rewarming.
Except when injury is minimal, treatment generally requires a hospital stay of several days, during which hydrotherapy and physical therapy are used to restore the affected part to health. Experts recommend a cautious approach to tissue removal, and advise that 22–45 days must pass before a decision on amputation can safely be made.
Expected results
The rapid rewarming approach to frostbite treatment, pioneered in the 1980s, has proved to be much more effective than older methods in preventing tissue loss and amputation. The extreme, throbbing pain that many frostbite sufferers endure for days or weeks after rewarming is not the only prolonged symptom of frostbite.
During the first weeks or months, people often experience tingling, a burning sensation, or a sensation resembling shocks from an electric current. Other possible consequences of frostbite include changes of skin color, nail deformation or loss, joint stiffness and pain, hyperhidrosis (excessive sweating), and heightened sensitivity to cold. For everyone, a degree of sensory loss lasting at least four years— and sometimes a lifetime—is inevitable.--123-Prevention
With the appropriate knowledge and precautions, frostbite can be prevented even in the coldest and most challenging environments. Appropriate clothing and footwear are essential. To prevent heat loss and keep the blood circulating properly, clothing should be worn loosely and in layers.
Covering the hands, feet, and head is also crucial for preventing heat loss. Outer garments need to be wind and water resistant, and wet clothing and footwear must be replaced as quickly as possible. Alcohol and drugs should be avoided because of their harmful effects on judgment and reasoning.
Experts also warn against alcohol use and smoking in the cold because of the circulatory changes they produce. Paying close attention to the weather report before venturing outdoors and avoiding unnecessary risks such as driving in isolated areas during a blizzard are also important.
