Frostbite and frostnip
Frostbite is damage to the skin and other tissues caused by freezing. Frostnip is a mild form of cold injury. In North America, frostbite is largely confined to Alaska, Canada, and the northern states. Recently, there has been a substantial decline in the number of cases and a change in the type of people at-risk, as outdoor winter activities have grown more popular and there are more homeless people. Exposure to temperatures a little below the freezing markcan take hours for skin to freeze, but very cold skin can freeze in minutesor seconds. Air temperature, wind speed, and moisture all affect how cold theskin becomes. The extent of permanent injury depends upon how long the skinand tissues remain frozen. Homeless people and others lacking strong self-preservation instincts face a greater risk of frostbite-related amputation because they are more likely to stay out in the cold when they should seek shelteror medical attention. Alcohol and smoking can increase the severity of injury. Other risk factors include inadequate clothing, previous cold injury, fatigue, wound infection, atherosclerosis (an arterial disease), and diabetes. Driving in poor weather can also be dangerous.
Frostbite injury is due to tissue freezing, tissue hypoxia, and the release of inflammatory mediators. Tissue freezing causes ice crystal formation and other changes that damage and kill cells. Tissue hypoxia (oxygen deficiency) occurs when the blood vessels in the hands, feet, and other extremities narrowin response to cold. Hypoxia, blood clots, and endothelial damage lead to therelease of inflammatory mediators (substances that act as links in the inflammatory process), which cause further endothelial damage, hypoxia, and cell destruction. Frostbite is classified by degree of injury (first, second, third, or fourth), or type (superficial and deep). Ninety percent of frostbite injuries affect the feet or hands. The remainder involve the ears, nose, cheeks,or penis. Once frostbite sets in, the affected part begins to feel cold andnumb; this is followed by clumsiness. The skin turns white or yellowish. As the skin begins to thaw, edema (excess tissue fluid) often accumulates, causing swelling. In second- and higher-degree frostbite, blisters appear. Third-degree cases produce deep, blood-filled blisters and, later, a hard black scab.Fourth-degree frostbite penetrates below the skin to the muscles, tendons, nerves, and bones. In severe cases the dead tissue can drop off. Infection ispossible. Like frostbite, frostnip is associated with ice crystal formation in the tissues, but the tissues aren't destroyed and the crystals dissolve when skin is warmed. Frostnip generally affects the earlobes, cheeks, nose, fingers, and toes. The skin turns pale and feels numb or tingly until warming begins.
Frostbite is diagnosed by a physical examination and may include x rays, angiography (x ray examination of the blood vessels using an injected dye), thermography (a heat-sensitive device to measure blood flow), and other tests. Diagnostic tests are only useful 3-5 days after rewarming, once the blood vessels have stabilized. Emergency medical help is necessary when frostbite is suspected. While waiting for help to arrive, remove wet or tight clothing and puton dry, loose clothing or wraps. Use a splint and padding to protect the injured area. Never rub the area with snow or anything else. Avoid partial thawing and refreezing, which makes the injury worse. Keep the affected part awayfrom heat sources such as campfires and car heaters. Rewarm in the field onlywhen emergency help will take more than two hours to arrive and refreezing can be prevented. Hospital treatment begins by rapidly rewarming the affectedpart to stop ice crystal formation and dilate narrowed blood vessels. Aloe vera is applied, and the affected part is splinted, elevated, and wrapped in adressing. Blisters may be cleaned. A tetanus shot and, possibly, penicillin,are used to prevent infection, and ibuprofen is given to fight inflammation.Narcotics are usually needed to reduce pain. Treatment generally requires a hospital stay of several days, during which hydrotherapy and physical therapyrestore the affected part to health. Experts recommend that 22-45 days must pass before a decision on amputation can safely be made. For frostnip in fingers, blow air on them or hold them under the armpits; cover other frostnippedareas with the hands. Never rub the injured areas. To speed recovery after leaving the hospital, alternative practitioners suggest: bathing the affected part in warm water or using contrast hydrotherapy (a series of hot and cold water applications), nutritional therapy, homeopathic and botanical therapies,acupuncture, and oxygen therapy.
Prolonged frostbite symptoms include throbbing pain, tingling, a burning sensation, or a sensation resembling electric shocks. Possible consequences of frostbite include skin--color changes, nail deformation or loss, joint stiffness and pain,hyperhidrosis (excessive sweating), and heightened sensitivity tocold. A degree of sensory loss lasts at least four years--and sometimes a lifetime. Frostbite can be prevented. Appropriate clothing and footwear are essential. Clothing should be worn loosely and in layers. The hands, feet, and head should be covered. Outer garments should be wind and water resistant, andwet clothing and footwear must be replaced quickly. Avoid alcohol, drugs, andsmoking. Pay close attention to the weather and avoid unnecessary risks suchas driving in isolated areas during a blizzard.