Cold injury

Cold injury
Other names	Cold weather injury
Frostbitten fingers after descent from mountain climbing
Symptoms	Numbness, skin discoloration, blisters, swelling, cold sensation[1][2]
Complications	Necrosis, gangrene, chronic pain, amputation[3][4]
Types	Freezing, nonfreezing[5]
Causes	Exposure to cold temperatures[6]
Risk factors	Military occupation, recreational winter activities, homelessness, inadequate or wet clothing, substance abuse, diabetes, peripheral vascular disease[6][7]
Diagnostic method	Based on symptoms[1][6]
Differential diagnosis	Hypothermia, Raynaud's phenomenon, chilblains (pernio), cold urticaria[8][9]
Prevention	Minimize cold exposure, wear protective clothing, change wet clothing, avoid substance use, maintain appropriate nutrition[1][4]
Treatment	Move to warm and dry environment, rewarming, medication, wound care, surgery[4][10]

Cold injury (or cold weather injury) is damage to the body from cold exposure, including hypothermia and several skin injuries.^[6] Cold-related skin injuries are categorized into freezing and nonfreezing cold injuries.^[5] Freezing cold injuries involve tissue damage when exposed to temperatures below freezing (less than 0 degrees Celsius).^[6][7] Nonfreezing cold injuries involve tissue damage when exposed to temperatures often between 0-15 degrees Celsius for extended periods of time.^[6] While these injuries have disproportionally affected military members, recreational winter activities have also increased the risk and incidence within civilian populations.^[6] Additional risk factors include homelessness, inadequate or wet clothing, alcohol abuse or tobacco abuse, and pre-existing medical conditions that impair blood flow.^[6][7]

Freezing cold skin injuries include frostbite and frostnip.^[8] These injuries often affect the fingers, toes, nose, and ears since they are less commonly covered by clothing when in cold environments.^[1] Affected skin becomes numb, turns white or blue, and develops blisters.^[1] Frostnip is a superficial skin injury that won't freeze the skin or cause long-term damage.^[8] Frostbite involves freezing of fluids inside and outside of cells that results in cell breakdown, electrolyte imbalances, and inflammation.^[8] Surrounding blood vessel constriction and injury disrupts blood flow to affected tissue, which may cause tissue death (necrosis).^[11] Diagnosis is based on symptoms, but imaging can help assess viable tissue and risk of amputation.^[6] Pre-hospital treatment involves transfer to a warm environment, changing wet clothing, and rapid rewarming with warm water if refreezing is not expected.^[11] Hospital management involves rewarming, wound care, and medications to treat pain and possible blood clots.^[11] Amputation of unsalvageable tissue may be required weeks to months after initial injury.^[11]

Nonfreezing cold skin injuries include trench foot, a subclass of immersion foot caused by exposure to cold temperatures.^[2] These injuries often affect the feet after being subjected to wet cold for several hours or days.^[4] Affected individuals report a tingling or numbing sensation, red or blue discoloration, and swelling or blisters in affected skin.^[2] The mechanism of injury isn't fully understood, but may involve cold-induced damage to blood vessels and nerves that results in small blood vessel (capillary) destruction, swelling, and tissue necrosis.^[5] Diagnosis is based on symptoms.^[2] Pre-hospital treatment includes transfer to a warm environment and exchanging wet clothing.^[4] Hospital management includes gradual rewarming with air drying, elevating affected skin, and pain management.^[4]