Let’s talk about FROSTBITE, BRRRRRRR.
Background
Results from the freezing of tissue that are exposed to temperatures below their freezing point, resulting in direct ice crystal formation and cellular lysis with microvascular occlusion
Most of the damage occurs as a result of a freeze thaw cycle with endothelial damage and cellular death resulting in osmotic gradient changes, initiation of the arachidonic acid cascade, vasoconstriction, and hematologic abnormalities including thrombosis
Risk correlated with temperature and wind speed
Risk is <5% when ambient temperature (includes wind chill) is > –15°C (5°F)
Most often occurs at ambient temperature < –20°C (–4°F)
Wetness and humidity increase the risk (water has 25x thermal conductivity of air)
Can develop within 2-3sec when metal surfaces that are at or below –15°C (5°F) are touched
Most commonly affects distal part of extremities, face, nose, and ears
The severity of irreversible damage is most closely related to ambient temperature and length of time the tissue remains frozen
High-risk groups: outdoor workers, elderly, homeless, drug or alcohol abusers, psychiatric disease, high-altitude or cold-weather athletes, military personnel
"Hunter's response" - prolonged repeated exposure to cold is protective
Classification
Frostbite is classically categorized into four levels of injury.
Management
The initial treatment in the Emergency Department for all degrees of frostbite is the same. Addressing ABC’s, trauma evaluation, removing wet and constrictive clothing, treatment of concomitant hypothermia (must rewarm to a core temperature of at least 35°C), and identification of other injuries should be confirmed in all cold injury cases if warranted.
THAWING: Do NOT attempt until the risk of refreezing is eliminated. Refreezing will cause even more severe damage. Rapid active rewarming is the core of therapy and should be initiated as soon as possible. Best performed in a circulating water bath around 37°C to 39°C. Frostbitten faces can be thawed using warm water compresses, and ears may be thawed with small bowls of warm water. Immersion rewarming can be discontinued when the affected area developed a red or purple appearance and becomes pliable to the touch.
Analgesia: rewarming is very painful, treat your patient's pain!
Local wound care: Gently dry, elevate, and apply bulky dressing to the affected area. Compartment syndrome is a known complication, so maintain a high suspicion.
Update tetanus as needed
Empiric prophylactic antibiotics are not needed and are controversial.
Surgical management may be required if wet gangrene or infection occurs, but this is typically reserved for late frostbite management after the rewarming phase in days to weeks following initial presentation
Dispo Dispo Dispo
Patients with superficial local frostbite may be discharged home if social circumstances allow. Patients unable to care for themselves adequately should never be discharged into subfreezing temperatures.
Significant injuries will require admission.
References:
http://www.emdocs.net/brrr-ed-presentation-evaluation-and-management-of-cold-related-injuries/
http://emedicine.medscape.com/article/926249-treatment#showall
https://wikem.org/wiki/Frostbite