Frostbite is an injury to skin or other living tissue that is allowed to freezing,[ especially affecting the , , nose, , and chin.][ Complications may include hypothermia or compartment syndrome.][
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People who are exposed to low temperatures for prolonged periods, such as winter sports enthusiasts, military personnel, and the Homelessness, are at greatest risk.[ Other risk factors include drinking alcohol, smoking, mental health problems, certain medications, and prior injuries due to cold.][ Diagnosis is based on symptoms.][ A bone scan or MRI may help in determining the extent of injury.][
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Prevention consists of wearing proper, fully-covering clothing, avoiding low temperatures and wind, maintaining hydration and nutrition, and sufficient physical activity to maintain core temperature without exhaustion.[ Treatment is by rewarming, immersion in warm water (near body temperature), or body contact, and should be done only when a consistent temperature can be maintained so that refreezing is not a risk.][ Rapid heating or cooling should be avoided since it could potentially cause burning or heart stress.][ The use of ibuprofen and tetanus vaccine is recommended for pain relief or to reduce swelling or inflammation.][ For severe injuries, iloprost or may be used.][ Surgery, including amputation, is sometimes necessary.]
Evidence of frostbite occurring in humans dates back 5,000 years.[ The most common age group affected is those 30 to 50 years old.][ Its first formal description was in 1813 by Dominique Jean Larrey, a physician in Napoleon's army, during its invasion of Russia.][ Frostbite reports were largely military until the late 1950s.]
Signs and symptoms
Areas that are usually affected include cheeks, ears, nose and fingers and toes. Frostbite is often preceded by frostnip.
First degree
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First-degree frostbite is superficial, surface skin damage that is usually not permanent.
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Early on, the primary symptom is loss of feeling in the skin. In the affected areas, the skin is numb, waxy, and possibly swollen, with a reddened border.
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In the weeks after injury, the skin's surface may slough off.
Second degree
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In second-degree frostbite, the skin develops clear early on, and its surface hardens.
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In the weeks after injury, this hardened, blistered skin dries, blackens, and peels.
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At this stage, lasting cold sensitivity and numbness can develop.
Third degree
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In third-degree frostbite, the layers of tissue below the skin freeze.
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Symptoms include blood blisters and "blue-grey discoloration of the skin".
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In the weeks after injury, pain persists and a blackened crust (eschar) develops.
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There can be long-term and damage to Epiphyseal plate.
Fourth degree
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In fourth-degree frostbite, structures below the skin, like muscles, tendon, and bone, are involved.
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Early symptoms include a colorless appearance of the skin, a hard texture, and painless rewarming.
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Later, the skin becomes black and Mummy. The amount of permanent damage can take one month or more to determine. Autoamputation can occur after two months.
Causes
Risk factors
The major risk factor for frostbite is exposure to cold through geography, occupation and/or recreation. Inadequate clothing and shelter are major risk factors. Frostbite is more likely when the body's ability to produce or retain heat is impaired. Physical, behavioral, and environmental factors can all contribute to the development of frostbite. Immobility and physical stress (such as malnutrition or dehydration) are also risk factors.
Mechanism
Freezing
In frostbite, cooling of the body causes narrowing of the blood vessels (vasoconstriction). Prolonged exposure to temperatures below may cause ice crystals to form in the tissues, and prolonged exposure to temperatures below may cause ice crystals to form in the blood.
Rewarming
Rewarming, though vital, causes tissue damage through reperfusion injury, which involves vasodilation, swelling (edema), and poor blood flow (stasis). Platelet is another possible mechanism of injury. Blisters and spasm of blood vessels (vasospasm) can develop after rewarming.
Non-freezing cold injury
The process of frostbite differs from the process of non-freezing cold injury (NFCI). In NFCI, temperature in the tissue decreases gradually. This slower temperature decrease allows the body to try to compensate through alternating cycles of closing and opening blood vessels (vasoconstriction and vasodilation). If this process continues, inflammatory act in the area. Small Thrombus (microthrombi) form and can cut off blood to the affected area (known as ischemia) and damage nerve fibers. Rewarming causes a series of inflammatory chemicals such as to increase localized clotting.
Pathophysiology
The pathological mechanism by which frostbite causes body tissue injury can be characterized by four stages: Prefreeze, freeze-thaw, vascular stasis, and the late ischemic stage.
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Prefreeze phase: involves the cooling of tissues without ice crystal formation.
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Freeze-thaw phase: ice-crystals form, resulting in cellular damage and death.
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Vascular stasis phase: marked by blood coagulation or the leaking of blood out of the vessels.
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Late ischemic phase: characterized by inflammatory events, ischemia and tissue death.
Diagnosis
Frostbite is diagnosed on the basis of signs and symptoms as described above, and by Medical history. Other conditions that can have a similar appearance or occur at the same time include:
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Frostnip, a precursor to frostbite with a similar appearance, but without ice crystal formation in the skin. Whitening of the skin and numbness reverse quickly after rewarming.
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Trench foot, damage to nerves and blood vessels that results from exposure to cold wet (non-freezing) conditions.
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Chilblains or chilblains, inflammation of the skin from exposure to wet, cold (non-freezing) conditions. They can appear as various types of ulcers and blisters.
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Bullous pemphigoid, a condition that causes itchy blisters over the body that can mimic frostbite.
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Levamisole toxicity, a vasculitis that can appear similar to frostbite.
People who have hypothermia often have frostbite as well.
Prevention
The Wilderness Medical Society recommends covering the skin and scalp, taking in adequate nutrition, avoiding constrictive footwear and clothing, and remaining active without causing exhaustion. Supplemental oxygen may also be of use at high elevations. Repeated exposure to cold water makes people more susceptible to frostbite.
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Avoiding temperatures below −23 °C (-9 °F)
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Avoiding moisture, including in the form of Perspiration and/or skin Moisturizer
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Avoiding alcohol and drugs that impair circulation or natural protective responses
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Layering clothing
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Using chemical or electric warming devices
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Recognizing early signs of frostnip and frostbite
Treatment
Individuals with frostbite or potential frostbite should go to a protected environment and get warm fluids. If there is no risk of re-freezing, the extremity can be exposed and warmed in the underarm of a companion or the groin. If the area is allowed to refreeze, there can be worse tissue damage. If the area cannot be reliably kept warm, the person should be brought to a medical facility without rewarming the area. Rubbing the affected area can also increase tissue damage. Aspirin and ibuprofen can be given in the field
The first priority in people with frostbite should be to assess for hypothermia and other life-threatening complications of cold exposure. Before treating frostbite, the core temperature should be raised above 35 °C. Oral or intravenous (IV) fluids should be given.
Other considerations for standard hospital management include:
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wound care: can be drained by needle aspiration, unless they are bloody (Bleeding). Aloe vera gel can be applied before breathable, protective dressings or bandages are put on.
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antibiotics: if there is trauma, skin infection (cellulitis) or severe injury
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Tetanospasmin: should be administered according to local guidelines. Uncomplicated frostbite wounds are not known to encourage tetanus.
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pain control: NSAIDs or are recommended during the painful rewarming process.
Rewarming
If the area is still partially or fully frozen, it should be rewarmed in the hospital with a warm bath with Povidone-iodine or chlorhexidine antiseptic.
Medications
People with potential for large amputations and who present within 24 hours of injury can be given TPA with heparin.[ These medications should be withheld if there are any contraindications. Bone scans or CT angiography can be done to assess damage.]
Blood vessel dilating medications such as iloprost may prevent blood vessel blockage.
A systematic review and metaanalysis revealed that iloprost alone or iloprost plus recombinant tissue plasminogen activator (rtPA) may decrease amputation rate in case of severe frostbite in comparison to buflomedil alone with no major adverse events reported from iloprost or iloprost plus rtPA in the included studies.
Surgery
Various types of surgery might be indicated in frostbite injury, depending on the type and extent of damage. Debridement or amputation of Necrosis tissue is usually delayed unless there is gangrene or systemic infection (sepsis).
Prognosis
Tissue loss and autoamputation are potential consequences of frostbite. Permanent nerve damage including loss of feeling can occur. It can take several weeks to know what parts of the tissue will survive.
Grades
Grade 1: if there is no initial lesion on the area, no amputation or lasting effects are expected
Grade 2: if there is a lesion on the distal body part, tissue and fingernails can be destroyed
Grade 3: if there is a lesion on the intermediate or near body part, auto-amputation and loss of function can occur
Grade 4: if there is a lesion very near the body (such as the carpals of the hand), the limb can be lost. Sepsis and/or other systemic problems are expected.
A number of long term sequelae can occur after frostbite. These include transient or permanent changes in sensation, paresthesia, increased sweating, cancers, and bone destruction/arthritis in the area affected.
Epidemiology
There is a lack of comprehensive statistics about the epidemiology of frostbite. In the United States, frostbite is more common in northern states. In Finland, annual incidence was 2.5 per 100,000 among civilians, compared with 3.2 per 100,000 in Montreal. Research suggests that men aged 30–49 are at highest risk, possibly because of occupational or recreational exposures to cold.
History
Frostbite has been described in military history for millennia. The Greeks encountered and discussed the problem of frostbite as early as 400 BC.
Society and culture
Several notable cases of frostbite include:
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Lawrence Oates, an English army captain and Antarctic explorer who in 1912 died of complications of frostbite
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Harold Bride, the junior wireless operator of , who suffered severe frostbite on his feet as he and other survivors stood for over an hour on the back of a capsized lifeboat knee-deep in freezing water—Bride had to be carried off from the rescue vessel after it arrived in New York
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Noted American rock climber Hugh Herr, who in 1982 lost both legs below the knee to frostbite after being stranded on Mount Washington (New Hampshire) in a blizzard
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Beck Weathers, a survivor of the 1996 Mount Everest disaster who lost his nose and hands to frostbite
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Scottish mountaineer Jamie Andrew, who in 1999 had all four limbs amputated as a result of sepsis from frostbite sustained after becoming trapped for four nights whilst climbing Les Droites in the Mont Blanc massif
Research directions
Evidence is insufficient to determine whether or not hyperbaric oxygen therapy as an adjunctive treatment can assist in tissue salvage.
Medical sympathectomy using intravenous reserpine has also been attempted with limited success.
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