Risk factors. Frostbite is often associated with risk factors such as alcohol or drug intoxication, vehicular failure or trauma, immobilizing trauma, psychiatric illness, homelessness, Raynaud phenomenon, peripheral vascular disease, diabetes, inadequate clothing, previous cold-weather injury, outdoor winter recreation, and the use of certain medications (eg, beta-blockers).1-3 Apart from environmental exposure, frostbite can also occur by direct contact with freezing materials, such as ice packs or industrial refrigerants.3
Differential includes nonfreezing injuries
Frostnip, pernio, and trench foot are other cold-weather injuries distinguished by the absence of tissue freezing.4 Raynaud phenomenon is a condition that is triggered by either cold temperatures or emotional stress.5
Frostnip is characterized by pallor and paresthesia of exposed areas. It may precede frostbite, but it quickly resolves after rewarming.2
Pernio occurs when skin is exposed to damp, cold, nonfreezing environments.6 It results in edematous and inflammatory skin lesions that may be painful, pruritic, violaceous, or erythematous.6 These lesions are typically found over the fingers, toes, nose, ears, buttocks, or thighs.4,6 Pernio may be classified as either primary or secondary disease.5 Primary pernio is considered idiopathic.6 Secondary pernio is thought to be either drug induced or due to underlying autoimmune diseases, such as hepatitis or cryopathy.6
Trench foot develops under similar conditions to pernio but requires exposure to a wet environment for at least 10 to 14 hours.7 It is characterized by foot pain, paresthesia, pruritus, edema, erythema, cyanosis, blisters, and even gangrene if left untreated.7
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