Frostbite

Basics

A severe localized injury due to cold exposure, causing tissue to freeze, resulting in direct cellular injury and progressive dermal ischemia (most commonly of exposed hands, feet, face, and ears)
Systems affected: integumentary, vascular, muscular, skeletal, nervous
Synonym: dermatitis congelationis; freezing cold injury (FCI)

Predominantly adults but can affect all ages
Predominant sex: male ≤ female, potentially more common in females due to increased surface area in conjunction with less body mass although exposure rates in males may be higher (1)

Prolonged exposure to cold
Ice crystals form intracellularly and extracellularly. Vasoconstriction reduces blood flow, and microvascular endothelial injury leads to ischemia. Cellular dehydration leads to abnormal electrolyte concentrations and cell death.
In severe cases, tissue injury extends to muscle and bone leading to necrosis and mummification. Rewarming injured endothelium results in edema and bullae as the ice crystals melt. Inflammatory mediators such as prostaglandins and thromboxane A2 induce vasoconstriction and platelet aggregation, worsening ischemia.
In severe frostbite, the chronic inflammation can result in an imbalance of proinflammatory and anti-inflammatory macrophages, which can lead to delayed healing (2).
If refreezing occurs after thawing, cascade of events are more extreme (1).

Prolonged exposure to below freezing temperatures, especially combined with wind and/or water exposure
High-altitude activities, such as mountaineering
Military operations in cold environments
Constricting or wet clothing with inadequate insulation
Altered mental status due to alcohol, drugs, or psychiatric illness
The experience of homelessness
Previous cold-related injury
Dehydration and/or malnutrition
Conditions that interfere with total heat production and/or thermoregulation (i.e., endocrine abnormalities) (1)
Conditions that promote loss of body heat including chronic skin conditions, hyperhidrosis, burns (including sunburns) (1)
Hypothermia
Any condition that results in decreased vasoconstriction and/or vascular pathology as in (1):
- Smoking; Raynaud phenomenon; peripheral vascular disease; diabetes

Dress in layers with appropriate cold weather gear and avoid clothing that is too constricting.
Cover exposed areas and extremities appropriately.
Stay dry; avoid alcohol and minimize wind exposure.
Ensure adequate hydration and caloric intake.
Use supplemental oxygen at very high altitudes (>7,500 meters).
Exercise can protect against frostbite by increasing core and peripheral temperatures. Note: Caution should be made that the exercise will not lead to exhaustion and inability to seek for shelter/warmth.
Appropriate use of chemical or electric hand and foot warmers can help maintain peripheral warmth.
Recognize expected temperatures and take into consideration wind chills prior to exposure and, if possible, avoid exposure.
Avoid emollients on the skin as they can lead to a false sense of protection (1).
Avoid alcohol, caffeine, and other medications that can cause vasoconstriction (1).

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