Frostbite is a cold-related injury characterized by freezing of tissue. Most cases of frostbite are encountered in soldiers, in persons who work outdoors in the cold, in homeless people, in athletes engaging in sports with seasons extending into the cold months of the year, and in winter outdoor enthusiasts, such as Nordic skiers. [1, 2, 3, 4] . Other risk factors include chronic medical conditions (eg, diabetes, cardiovascular disease, peripheral vascular disease, Raynaud phenomena), African American race, vibration-induced white finger (VIWF), previous history of frostbite, and use of certain medications (eg, beta-blockers, sedatives). [5, 6]
Mountain frostbite is a variation observed among mountain climbers and others exposed to extremely cold temperatures and strong winds at high altitude. It combines tissue freezing with hypoxia and general body dehydration. 
Examples of frostbite are shown below.
Go to Frostbite for complete information on this topic.
Address life-threatening conditions, such as hypothermia or major trauma, first. Replace wet clothing with dry, soft clothing to minimize further heat loss, and initiate rewarming of the affected area as soon as possible. However, do not attempt rewarming if there is a danger of refreezing. Avoid rubbing the affected area with warm hands or snow, as this can cause further injury. If the affected body part is an extremity, wrap it in a bulky dressing or blanket for mechanical protection during transport. Also, remove jewelry from affected extremities. Oral hydration and administration of ibuprofen may improve outcome, if feasible. Avoid alcohol or sedatives, which can enhance heat loss and impair shivering. 
It is better to walk with frozen feet to shelter than to attempt rewarming at the scene; however, walking on frostbitten feet may cause tissue chipping or fracture.
Emergency Department Care
Address life-threatening conditions first. Fluid resuscitation, especially in persons with mountain frostbite, enhances blood flow and tissue perfusion. Rapidly rewarm the affected body part, avoiding further trauma. Tetanus prophylaxis should be administered if the patient's vaccination status is not current or unknown.
An appropriate warming technique is the use of a whirlpool bath or tub of water at 38-40°C. Mild antibacterial soap may be added. Avoid warmer temperatures or dry heat because of the risk of thermal injury.
If a tub is not available, use warm, wet packs at the same temperature. Avoid massaging the affected area, as this can cause further injury. Administer analgesics, such as morphine sulfate, as needed for pain. Ibuprofen should also be administered.
Thawing usually takes 20-40 minutes and is complete when the distal tip of the affected area flushes. Once thawed, keep the body part on sterile sheets, elevated, and splinted when possible. A cradle may be used over an injured lower extremity to avoid pressure or trauma.
Debride clear blisters to prevent thromboxane-mediated tissue injury. Leave hemorrhagic blisters intact to reduce the risk of infection. Apply topical aloe vera gel every 6 hours with dressing changes.
Thrombolytic therapy with tissue plasminogen activator should be considered for deep frostbite within 24 hours of thawing. When administered within 24 hours of thawing, it has been shown to decrease amputation rates. It is generally administered as a bolus followed by an infusion, along with heparin or enoxaparin. [9, 10] Some protocols include the addition of the vasodilator iloprost, a prostacyclin analog, which has been shown to reduce amputation rates. [11, 12]
Angiography can be used to assess the tissue before and after thrombolysis.
Angiography or technetium Tc 99 bone scanning can be used to determine tissue viability and may help surgical consultants in determining the need for tissue debridement or amputation. 
In patients with an associated dislocation, perform reduction as soon as thawing is complete. Manage fractures conservatively until postthaw edema has resolved.
The only indication for early surgical intervention is debridement of blisters or necrotic tissue and fasciotomy in the case of compartment syndrome. Early surgical consultation for amputation is rarely needed. It often takes 1-3 months for frostbitten tissue to be declared viable. The affected area generally heals or mummifies without surgery. Therefore, unless guided by scintigraphy, delay amputation as long as possible.
Lower extremity involvement, infection, and delay in seeking medical attention are associated with an increased risk of operative therapy.
Surgical consultation is appropriate for guiding long-term management, including debridement for infections not responding to conservative management, or for skin grafting.
Transfer the patient to another facility if treating personnel are unfamiliar with the management of frostbite and its sequelae.
In some settings, burn units have particular expertise in managing severe frostbite injuries. In one report, 29% of homeless patients admitted to a burn unit were admitted for frostbite.  Therefore, transfer to a facility with a burn unit may be considered.