Frostbite Treatment & Management

The goal of frostbite treatment is to salvage as much tissue as possible, to achieve maximal return of function, and to prevent complications.^[30] If treating personnel are unfamiliar with the management of frostbite and its sequelae, transfer of the patient to another facility should be considered. 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.^[31] Therefore, transfer to a facility with a burn unit may be an option.

Be sure to correct the ABCs (A irway, B reathing, and C irculation) and life-threatening conditions before treating frostbite. Make sure that the frostbitten area does not refreeze. Rewarm the frostbitten area as quickly as possible to salvage as much tissue and function as possible. The use of circulating water at 40-42°C is common. Do not allow the water to get too hot or too cold. Avoid premature termination of the rewarming process. Remember to treat pain associated with rewarming.

Avoid early amputation until after the nonviable tissue is clearly demarcated. Inform patients that the injury site is more prone to recurrent damage when exposed to even moderate changes in environmental temperature.

Consider obtaining a photographic record on admission, 24 hours after admission, and serially every 2-3 days until discharge.

The management of frostbite itself may be divided into 3 phases: field management, rewarming, and postrewarming management.^[17]

The first step in the management of frostbite is prevention. The US Army decreased the incidence of cold injury of all types in soldiers from 1985-1999. This was accomplished through training, education, and improved clothing.^[18] When suspected frostbite does occur, transport to a trauma or burn center becomes a priority. Field rewarming should be started only if the time to arrival at a definitive care center exceeds 2 hours.

As a general principle, always address the ABCs and treat any life-threatening conditions (eg, hypothermia) first. Correct any systemic hypothermia to a core temperature of 34°C before treating the frostbite.

Remove the patient from cold. Replace wet and constrictive clothing with dry loose clothing. Dress the extremity in a manner that minimizes mechanical trauma.

Rewarm the frostbitten area if no danger of refreezing is observed. However, rewarming should be avoided if it cannot be maintained (freeze-thaw-freeze cycle). Walking on frozen frostbitten areas and risking tissue chipping and fracture is considered better than thawing and refreezing. Reports from Canada show that forced-air rewarming with portable units can be used effectively to warm victims of hypothermia and frostbite in the field and during transport to a regional medical center.^[32]

Rapid rewarming is the single most effective therapy for frostbite.^[33] Variations on the original work of McCauley et al are used at most centers experienced in the management of the frostbite patient.^[21] This includes admission of all frostbite patients to a specialty unit, if possible. Consider obtaining photographic records on admission, at 24 hours, and serially every 2-3 days until discharge.

On admission, rapidly rewarm the affected area in circulating water (ie, a whirlpool bath) at 40-42°C. The circulation of water allows a constant temperature to be applied to the affected area. Warming is continued for 15-30 minutes or until thawing is, by clinical assessment, complete (ie, when the distal area of the extremity is flushed, soft, and pliable).

Avoid inadvertent slow rewarming or overheating. Encourage active gentle motion of the frostbitten area during the rewarming. Constantly monitor water temperature to ensure it does not exceed 43.3°C. Thawing takes about 20-40 minutes for superficial injuries and as long as 1 hour for deep injuries.

The most common error in this stage of treatment is premature termination of the rewarming process because of reperfusion pain. Mechanical trauma (massaging or rubbing with ice or by hand) and rewarming at higher temperatures and for longer periods of time are detrimental to preserving viable tissue and should be avoided. Direct dry heating using fire or a heater can lead to burns secondary to loss of temperature sensation and so should be avoided.

Partial thawing and refreezing generate more damage than does prolonged freezing alone, through the release of multiple inflammatory mediators. In patients who experience a refreezing injury of thawed areas, rewarming should be delayed until it can be maintained.

Once the skin is thawed, protect the area from further injury and reexposure to cold. Elevate the area and splint the extremity. Change the sterile nonadherent dressing 2-4 times a day. Prevent infection. Aid circulation. Provide rehabilitation. Provide local wound care.

Aspirate clear blisters to prevent thromboxane- and prostaglandin-mediated tissue damage. In order to avoid desiccation and infection of underlying deep layers, do not debride hemorrhagic blisters. Manage fractures and dislocations conservatively until thawing is complete.

Carry out daily hydrotherapy for 30-45 min at 40°C.

Analgesics (eg, ibuprofen and morphine) for pain relief are indicated during and after rewarming.

Apply topical aloe vera cream to all frostbitten areas every 6 hours to inhibit the arachidonic cascade, especially thromboxane synthesis. Other arachidonic cascade inhibitor agents currently being investigated include topical methimazole (a thromboxane synthetase inhibitor) and topical methylprednisolone acetate (a phospholipase A₂ inhibitor).

In adult patients, medical sympathectomy with intravenous (IV) infusion of 0.5 mg of reserpine (an alpha-blocking agent) into the affected terminal artery achieves better pain relief and edema reduction than surgical sympathectomy does. The reserpine effect begins in 3-24 hours and persists for 2-4 weeks. However, the IV form is no longer available in the United States and has not been used on pediatric patients.

Administer tetanus prophylaxis (tetanus toxoid or immune globulin).

Antibacterial prophylaxis should be considered because the postthaw edema is predisposed to infection. Frostbite infections tend to involve staphylococci, streptococci, enterococci, and Pseudomonas pathogens. Avoid topical antibiotics, because they interfere with the aloe vera cream. Consider penicillin G IV every 6 hours for 48-72 hours.

There are several other medication regimens that appear potentially beneficial, but they have not been prospectively validated, and standard doses have not been established. Such regimens include daily infusion of low-molecular-weight dextran, which may prevent erythrocyte clumping in cold-injured blood vessels. Low-dose infusions of heparin may prevent microthrombosis.

In addition, one study suggests that intravenous heparin combined with intravenous tissue plasminogen activator (tPA) may improve outcome in patients with frostbite of the digits.^[34] Finally, bupivacaine has been used for either cervical or lumbar sympathetic blockade to decrease sympathetic tone and relieve pain, but its efficacy is unclear.

Other ancillary modalities that appear promising but have not been tested in well-controlled human trials include the following:

• Thrombolysis using intra-arterial tPA in deep frostbite to decrease tissue loss by 10% when administered within 24 hours of exposure
• Limaprost (a prostaglandin E₁ analogue) as a therapeutic vasodilator to increase peripheral blood flow
• Buflomedil (an alpha-blocker) to increase peripheral blood flow
• Hyperbaric oxygen (anecdotal)^[35]
• Subatmospheric pressure therapy (anecdotal)^[36]
• Pentoxifylline
• Vitamin C
• Superoxide dismutase
• Nifedipine

Animal models observing the effects of thrombolytics (eg, streptokinase and tPA) have shown promising results in tissue preservation. A small clinical trial also has documented improved benefit with thrombolytic use in extending the amount of viable tissue. In a retrospective study, Bruen et al noted that tPA, when used within 24 hours of injury, improved tissue perfusion and reduced the amputation rate in frostbite.^[37]

One study demonstrated that treatment with pentoxifylline, aspirin, and vitamin C improved tissue viability in frozen rat hind limbs when coupled with internal and external warming.^[38] Another study using an experimental rabbit model treated with hemodilution with dextran combined with external warming also showed a significant tissue survival advantage.^[39]

To date, no large prospective human clinical trials have been conducted that have evaluated the efficacy of these treatments and other adjuvant modalities, thereby mandating their routine use.

It may take weeks to months for frostbitten tissue to be declared viable. The affected area generally heals or mummifies without surgery. Lower-extremity involvement, infection, and delay in seeking medical attention are associated with an increased likelihood that operative therapy will be necessary.

Early surgery usually is contraindicated in frostbite, because of the time the nonviable tissue takes to demarcate. Older series show that performing debridement earlier than 2-3 weeks after warming significantly increases the amount of viable tissue removed and is harmful to the patient, resulting in increased amputation rate, mortality, and morbidity. The only indication for early surgical intervention is postthaw compartment syndrome warranting fasciotomy.

Whereas some advocate an aggressive approach, with bone and tissue scanning employed to identify nonviable tissue at 10 days, this is not considered routine or standard of care. Caregivers are cautioned to wait for demarcation of clearly necrotic tissue before surgical intervention. This usually takes about 3-4 weeks. Commonly accepted indications for surgical debridement at 3-4 weeks include gangrene and clearly necrotic or nonfunctional tissue.

Wet gangrene is treated by urgent surgical excision of the affected area.

Standard surgical techniques are used for excision and debridement after tissue demarcation. Amputation skin grafting and bone and tissue coverage, potentially with muscle flaps, may be considered.^[40]

Skin grafting may be required. Escharotomy may be appropriate if the eschar is preventing circulation or limb motion. Fasciotomy may be appropriate if elevated compartment pressure occurs. Escharotomy and fasciotomy have no proven prophylactic role in the management of frostbite. Ischemic injury in frostbite is most often caused by vascular compromise from thrombosis and not by compression from edematous tissue, making decompression unnecessary. Only when proven compartment syndrome is present is decompression needed.

Because of the extreme difficulty in differentiating viable tissue from nonviable tissue in the first few weeks after frostbite injury, amputation surgery is best avoided until complete demarcation and separation of gangrenous tissue occurs. This process normally takes 6-8 weeks. Consider early amputation if liquefaction, moist gangrene, or infection develops in the frostbitten area.

Surgical sympathectomy may be considered, though it has not been shown conclusively to improve tissue salvage except in cases of severe frostbite. Paradoxically, sympathectomy increases tissue edema formation if performed too early after the frostbite injury. If reserved for 24-48 hours after rewarming, sympathectomy increases peripheral blood flow to affected tissues. It is a useful treatment in the late sequelae of frostbite, including hyperhidrosis and pain.

Pressure dressings, occlusive dressings, and elastic wraps will decrease tissue perfusion and increase the risk of tissue loss. The presence of a concomitant injury with active bleeding requires direct pressure over the bleeding site, but caregivers should be aware that such actions are performed as life-saving measures and can result in increased morbidity.

In a report of a single patient treated with vacuum-assisted closure (VAC) therapy, Poulakidas et al described improved tissue salvage and early reepithelialization, suggesting that VAC may be of some benefit in the management of frostbite-induced tissue damage.^[36]

Because the initial insult is not predictive of the final outcome, most patients with frostbite must be hospitalized for 24-48 hours to assess the extent of injury. The mean length of hospital stay for all levels of frostbite ranges from 8.5-33.2 days.

Daily wound care includes bivalving of any constricting eschars. Most skin grafting and amputations occur during weeks 3 or 4 after the injury.

Use hydrotherapy (ie, whirlpool bath filled with lukewarm water [40°C] and surgical soap) for 30-45 minutes twice daily until the eschar sloughs off. This measure reduces infection, facilitates debridement, and softens the eschar.

Avoid smoking, because nicotine causes vasoconstriction.^[20] No restriction on diet is required, but a high-protein, high-calorie diet is suggested to promote healing.

Rest the injured area initially. Elevation helps to reduce swelling. Place cotton pledgets between frostbitten digits to decrease tissue maceration. Perform physical therapy to increase flexibility and dexterity once the injury begins to heal. Encourage active motion of the affected part as soon as possible.

Prevention is the key to decreasing the number and overall morbidity of frostbite injuries. Frostbite prevention involves having a working knowledge of the environmental risks and hazards of outdoor activities in colder climates, using adequately protective clothing against cold and wind, and having a basic field knowledge of treatment options for frostbite. In conditions conducive to frostbite, patients should be advised to do the following:

• Seek shelter from wind and cold
• Wear several layers of light, loose clothing, which traps air for insulation yet provides for adequate insulation; such layering provides better protection than a single bulky layer of heavy clothing
• Wear mittens instead of gloves because they decrease surface area exposure to the cold; if mittens are removed to allow use of the fingers, wear lightweight gloves under the mittens for protection
• Wear at least 2 pairs of socks
• Cover the face and head
• Choose fabrics suited for the cold (eg, fleece, polypropylene, wool)
• Avoid restrictive and tight clothing that reduces peripheral circulation
• Avoid getting clothing wet
• Avoid remaining in the same position for prolonged periods
• Check skin every 10-20 minutes for frostbite
• Avoid smoking, because it causes peripheral vasoconstriction

When frostbite injuries do occur, expeditious treatment at a specialty center results in the least amount of permanent disability and tissue loss.

Frostbite treatment is a multidisciplinary process and may involve the following specialists:

• Emergency physician to stabilize the patient
• Hospitalist to provide inpatient medical treatment
• Surgeon to provide surgical care
• Physical therapist to provide rehabilitation
• Psychiatrist to help the patient cope with any permanent disability

Early surgical consultation for amputation is rarely needed. Surgical consultation is appropriate for guiding long-term management, including debridement for infections that do not respond to conservative management or for skin grafting.

Long-term surgical management includes the following options:

• Debridement of demarcated nonviable tissue - The demarcation process usually takes 1-3 months from the time of initial exposure^[17]
• Skin grafting
• Reconstruction of nose, ears, fingers, and toes
• Referral for physical rehabilitation

Counsel patients that the frostbitten area is more vulnerable to future heat and cold injury. Encourage patients to undergo active physical therapy.

Further outpatient care includes wound management, analgesia, and avoiding re-exposure to the cold. The choice of outpatient medications is dictated by the patient’s hospital course and may include antibiotics, analgesics, and ibuprofen.