Approach

Life-threatening injuries, such as hypothermia or major trauma, take priority.[5]​ Fractures are managed conservatively until postwarming edema has resolved. If there is a risk of amputation, time is critical and transfer to a major trauma centre or vascular unit with access to modern treatments is urgent. The Canadian Frostbite Care Network Opens in new window Early surgical intervention is only indicated to assist in wound debridement or to treat complications such as compartment syndrome and ischemia from a constricting eschar or subeschar infection.[1]​ Oxygen should not be given routinely but may be given if the patient is hypoxic.[4] See Accidental hypothermia, Compartment syndrome of the extremities.

The mainstay of treatment of frostbite is rapid rewarming, but protection from refreezing must be assured before rewarming is started. Care includes hydration; nonsteroidal anti-inflammatory drugs (NSAIDs); adequate analgesia; tetanus prophylaxis; wound care; and iloprost (or thrombolytic therapy) if there is a risk that amputation may be required. Iloprost and recombinant tissue plasminogen activator (r-tPA) have revolutionized the treatment of severe frostbite, and treatment with them should ideally be started within 24 hours of injury.

Rapid rewarming

Rewarming should be initiated as soon as possible. However, refreezing will worsen the injury, so active rewarming should not be initiated until the patient can be assured safety from re-exposure to the cold.[5]

Rather than remain in the cold, it is better to walk with frostbitten feet to find shelter, even though this may cause bone chipping or fracture. Precautions that can be taken to protect injured tissue in the field include replacing wet clothing with dry, soft clothing, and wrapping extremities in a blanket for protection during transport.

Affected areas should be rapidly rewarmed in gently circulated warm water at until rewarming is complete (usually 15 to 30 minutes).[4] The Wilderness Medical Society recommends that the water is warmed to 98.6°F to 102.2°F (37°C to 39°C), while the American Heart Association and American Red Cross Guidelines for First Aid recommend a higher upper limit of 104°F (40°C).[4][32]​​​​ If a thermometer is not available, nonscalding water can be used, or water at a temperature that a non-frostbitten extremity can be comfortably submerged in for 45 minutes. Antibacterial soap or antiseptic solution can be added to protect against cellulitis, particularly if severe edema is present.[4] Warm wet packs can be used if a tub is not available. Temperatures above 104°F (40°C) or dry heat can cause thermal injuries and should be avoided. Rubbing the affected tissue for rewarming should always be avoided.[33] Jewelry should be removed from affected digits early because significant swelling can occur post-thaw and vascular compromise (tourniquet effect) may occur with tight rings. The affected extremity should be elevated above the level of the heart to avoid the development of dependent edema.[4][14]

Thawing is complete when the distal tip of the affected extremity flushes red or purple and the tissue becomes soft and pliable to the touch, signaling the end of vasoconstriction.[1][4][5]​​​[14][16][26][34]​​​​​[35][36][37][38][39][40]​ Active movement of the affected extremity helps promote perfusion and should be encouraged early, but patients should avoid walking on frostbitten extremities to avoid inadvertent injury.

Hydration

Aggressive hydration is important on initial presentation. Warmed fluids (at least to 98.6°F [37°C] but preferably 104°F [40°C] to 107.6°F [42°C]) can be given either intravenously or orally, depending on the patient's condition.[14] If fluids are given intravenously in the field, they should be infused in small rapid boluses (e.g., 250 mL) to avoid cooling in the environment.[4]

Nonsteroidal anti-inflammatory drug (NSAID)

An NSAID, such as ibuprofen, is recommended in all patients for analgesia and to reduce inflammation. There is a theoretical benefit to blocking the arachidonic acid pathway that produces prostaglandins and thromboxanes which lead to vasoconstriction and further tissue damage. While no outcome studies have been reported, unless there are contraindications, ibuprofen can be commenced in the field and continued until the frostbite has healed or when surgery is needed.[4]

Alternatively, aspirin may be used if ibuprofen is not available. Aspirin blocks the production of certain prostaglandins that are beneficial to wound healing and may be counterproductive.[4] However, a therapeutic analgesic dose of aspirin may still be used if ibuprofen is not available, because its antiplatelet action is thought to be beneficial.[1]

Additional analgesia

Opioids may be used if additional analgesia is required.[4] 

Antitetanus prophylaxis

Tetanus prophylaxis should be administered according to standard guidelines.​[4]

Wound care

Although there is a paucity of evidence to support blister management, it is common practice to debride white blisters in hospital, theoretically to prevent thromboxane-mediated tissue injury. First aid providers should not debride blisters in the field.[32] Hemorrhagic blisters should be kept intact to avoid infection.[4]

Blisters should be treated topically with aloe vera cream or gel before dressing application and reapplied at each dressing change.[4] Aloe vera is believed to decrease prostaglandin and thromboxane formation.[4][15]​​​ Padding with cotton or soft gauze should be used between digits to reduce tissue maceration, but circumferential dressings should be loose given the likelihood of the development of edema.[4]

Affected parts should be kept elevated and splinted if necessary.[4] Associated dislocations should be reduced as soon as thawing is complete. However, fractures must be managed conservatively until edema has resolved, to avoid the risk of compartment syndrome.

Surgical intervention may be required to debride ulcers and necrotic tissue in severe cases.

Daily hydrotherapy should be performed at 98.6°F to 102.2°F (37°C to 102.2°F (39°C) for 45 minutes in a tank with sodium chloride and calcium hypochlorite solution.[4] Surgical soap can be added instead of sodium chloride and calcium hypochlorite.

Serial photographs can be helpful to document evolution of the injury and healing.[1]

It usually takes 1 to 3 months to assess whether frostbitten and surrounding tissue is viable.[4] To determine prognosis, it is useful to classify injured tissue based on the topography of the lesion and early bone scan results, beginning at day 0 (just after rewarming).[1] Good clinical prognostic signs during the healing process are early recovery of pinprick sensation, healthy-appearing skin, and the presence of clear (rather than hemorrhagic) blebs.[41]​ Poor clinical prognostic signs include hemorrhagic blebs that do not extend distally, cyanosis, and tissue that appears frozen.

Rehabilitation

Early rehabilitation is essential for functional recovery and to prevent joint stiffness.[42]​ A high-protein, high-calorie diet helps promote healing.

Antibiotic therapy

The use of prophylactic antibiotics is controversial and is typically not recommended unless there are signs of infection, or for more severe injuries (grades 3 and 4) or if there is severe edema after thawing.[4][14][43]​​​​​ If the damaged tissue appears infected, coverage should include Streptococcus species, Staphylococcus species, Pseudomonas species, and gram-negative bacteria.

When frostbite is severe, the risk of anaerobic infection is significant. This should be taken into consideration when choosing antibiotic regimens and making decisions regarding surgical intervention.[33]

Iloprost or thrombolytic therapy

Patients with Grade 2 to 4 frostbite should be transported to be treated in units familiar with the treatment of moderate to severe frostbite.

It is usually possible to determine if a patient is likely to require an amputation. The decision about who to treat with iloprost or r-tPA (e.g., alteplase) is a judgement call for clinicians. In addition to the degree of severity, factors that influence the clinical decision include hand dominance, thumb injury, and the patient’s occupation (e.g., craftsman, musician, laborer). In the experience of the authors, units treating large numbers of patients with moderate to severe frostbite will have a better concept of the risk versus benefit of treating or not treating an individual patient, and which agent is most appropriate. Units with less experience, or who cannot access iloprost, might consider that the risk of r-tPA is only balanced by the benefit of treating more severe (Grade 3 to 4) frostbite.

Although it is more widely available, r-tPA is more complex to administer and has more adverse effects than iloprost. Both drugs are usually provided in a critical care or high-dependency setting with close monitoring of blood pressure and symptoms. Iloprost is given intravenously and r-tPA can be given intravenously or intra-arterially. r-tPA demonstrates better efficacy (and a higher complication rate) when given intra-arterially. It requires more intensive monitoring than iloprost and coagulation tests. In the opinion of the authors, there are no good indications for the use of r-tPA if iloprost is available.

Iloprost is a prostacyclin mimetic and a potent vasodilator that also reduces inflammation, and inhibits platelet aggregation.[4] It is approved in the US for the treatment of severe frostbite to reduce the risk of digit amputations, and has been used in Europe for many years (although it is not approved there for this indication).[44] The FDA approval was based on an open-label study of 47 patients initially given aspirin and buflomedil (a vasoactive drug that is no longer available). They were then randomized to receive for 8 days: aspirin and buflomedil; or aspirin plus iloprost; or aspirin plus iloprost (plus r-tPA for the first day only). Effectiveness was assessed by technetium bone scanning, which showed excellent correlation with anatomical amputation levels (predictive value of positive findings, 0.996). The risk of amputation was significantly lower with iloprost or iloprost plus r-tPA.[44]

Where there is a risk of amputation, iloprost can be given intravenously for deep frostbite extending to the distal interphalangeal joint or further (Grades 2 to 4). Despite a lack of strong evidence, iloprost is the first-line choice for Grades 3 to 4 frostbite.[4][44][45]​ Iloprost has a lower adverse effect and complication rate compared with r-tPA, so it may be considered as treatment for Grade 2 as well as more severe (Grades 3 and 4) frostbite. It should be given as soon as possible, but can be administered up to 72 hours after rewarming.[4] It is particularly helpful if angiography is not available or there are contraindications to thrombolysis.[14] The drug is typically given for approximately 6 hours a day for a total of 5 to 8 days in cases of grade 3 or 4 frostbite.[Figure caption and citation for the preceding image starts]: Typical frostbite injuries in the hands and feet of a climber with mildly hemorrhagic bullae presenting 3 days after exposure. The bullae were aseptically aspirated and a 5-day iloporost infusion resulted in a complete recoveryHallam M-J, BMJ 2010;341:c5864 [Citation ends].com.bmj.content.model.Caption@509d7028

r-tPA is more widely available than iloprost. Only deep injuries with likely amputations (e.g., extending into the proximal interphalangeal joints of digits, Grades 3 to 4) should be considered for thrombolytic therapy.[4] r-tPA may be considered within 24 hours after thawing with appropriate angiographic intervention for deep frostbite at the distal interphalangeal joint or more proximal to this.[4] Time to thrombolysis appears to be critical.[4]

Contraindications to r-tPA include trauma, recent surgery and recent stroke.

Heparin is used in r-tPA protocols, but there is no evidence to support the use of heparin alone for treating frostbite either in the field or in hospital.[4]

Low molecular weight dextran

The role of low molecular weight dextran has significantly diminished with the increasingly widespread availability of iloprost.[44] If iloprost is available there is no role for low molecular weight dextran. It is associated with a small bleeding risk and anaphylaxis and a test dose should be given prior to use.[4]

Surgery

Early surgical intervention is only indicated to assist in the debridement of ulcers and necrotic tissue, or if the patient presents with signs of sepsis.[41]​ See Sepsis in adults.

Fasciotomy is required to treat compartment syndrome that may be induced by edema associated with thawing.[4]

Early amputation is rarely required. Most injuries will heal or mummify without surgery, so amputation should be delayed for as long as possible. It is also recommended that surgery be delayed until 6 to 12 weeks post-injury because surgical trauma can interfere with wound healing in the proximal tissue and thereby increase tissue loss. This also allows a sufficient period of time for demarcation of the wounds to help guide surgical procedures (skin graft, flap, or amputation).[16][42] Risk factors for amputation include late presentation, lower extremity involvement, and infection of the injured tissue.

Skin grafting can be considered in selected severely injured patients.[46][Figure caption and citation for the preceding image starts]: A typical frostbite affecting the hallux and third left toes showing the initial injury at presentation at base camp on Everest (A), at 6 weeks (B), and at 10 weeks (C). Note the delayed surgical amputation of the hallux after definitive demarcation and the recovery of the third digit after appropriate managementHallam M-J, BMJ 2010;341:c5864 [Citation ends].com.bmj.content.model.Caption@69405280

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