Frostbite

In the field, frostbitten extremities should be rewarmed rapidly by totally immersing the affected area in water that is tolerably warm to the touch (37 to 39° C). Because the area is numb, rewarming with an uncontrolled dry heat source (eg, fire, heating pad) risks burns. Rubbing may further damage tissue and is avoided.

The longer an area remains frozen, the greater the ultimate damage may be. However, thawing the feet is inadvisable if a patient must walk any distance to receive care because thawed tissue is particularly sensitive to the trauma of walking and, if refrozen, will be more severely damaged than if left frozen. If thawing must be delayed, the frozen area is gently cleansed, dried, and protected in sterile compresses. Patients are given analgesics, if available, and the whole body is kept warm.

Once the patient is in the hospital, core temperature is stabilized and extremities are rapidly rewarmed in large containers of circulating water kept at about 37 to 39° C; 15 to 30 minutes is usually adequate. Thawing is often mistakenly ended prematurely because pain may be severe during rewarming. Parenteral analgesics, including opioids, may be used.

Patients are encouraged to move the affected part gently during thawing. Large, clear blisters are left intact or aspirated using sterile technique. Hemorrhagic blisters are left intact to avoid secondary desiccation of deep dermal layers. Broken vesicles are debrided. If there is no perfusion after thawing, the administration of papaverine (a vasodilator), nicardipine, or nitroglycerin may be considered. If flow remains absent, intra-arterial or intravenous thrombolytic (fibrinolytic) therapy may be considered (1 Treatment reference Frostbite is injury due to freezing of tissue. Initial manifestations may be deceptively benign. Skin may appear white or blistered and is numb; rewarming causes substantial pain. Gangrene may... read more ). This treatment should be followed with enoxaparin 1 mg/kg subcutaneously twice a day for 14 days.

Anti-inflammatory measures (eg, topical aloe vera every 6 hours and ibuprofen 400 to 600 mg orally every 8 hours) probably help. Affected areas are left open to warm air, and extremities are elevated to decrease edema. Anticoagulants, IV low molecular weight dextran, and intra-arterial vasodilators (eg, reserpine, tolazoline) have no proven clinical benefit. Phenoxybenzamine, a long-acting alpha-blocker, at a dosage of 10 to 60 mg orally once a day may theoretically decrease vasospasm and improve blood flow. For severe injury presenting within 48 hours, infusion of a prostacyclin analog such as iloprost should be considered.

Preventing infection is fundamental; streptococcal prophylaxis (eg, with penicillin) should be considered, especially if there is gross contamination or crush injury. If wet gangrene is present, broad-spectrum antibiotics are used. Tetanus toxoid Treatment Tetanus is acute poisoning resulting from a neurotoxin produced by Clostridium tetani. Symptoms are intermittent tonic spasms of voluntary muscles. Spasm of the masseters accounts for... read more is given if vaccination is not up to date. If tissue damage is severe, tissue pressure is monitored (see Compartment Syndrome: Diagnosis Diagnosis Compartment syndrome is increased tissue pressure within a closed fascial space, resulting in tissue ischemia. The earliest symptom is pain out of proportion to the severity of injury. Diagnosis... read more , How To Measure Compartment Pressure in a Forearm How To Measure Compartment Pressure in a Forearm Compartment pressure is measured to assist in diagnosing compartment syndrome. Measurement of compartment pressure is a hospital-based procedure that requires considerable technical skill; an... read more , and How To Measure Compartment Pressure in the Lower Leg How To Measure Compartment Pressure in the Lower Leg Compartment pressure is measured to assist in diagnosing compartment syndrome. Measurement of compartment pressure is a hospital-based procedure that requires considerable technical skill; an... read more ).

Adequate nutrition is important to sustain metabolic heat production. Pre-thaw, consider using Doppler ultrasonography Doppler In ultrasonography, a signal generator is combined with a transducer. Piezoelectric crystals in the signal generator convert electricity into high-frequency sound waves, which are sent into... read more to assess pulses and tissue appearance.

Other imaging tests include radionuclide scanning, MRI, microwave thermography, and laser-Doppler flowmetry to help assess circulation, determine tissue viability, and thus guide treatment. MRI and particularly magnetic resonance angiography may establish the line of demarcation before clinical demarcation and thus make earlier surgical debridement or amputation possible. However, whether earlier surgery improves long-term outcome is unclear. Usually, surgery is delayed as long as possible because the black carapace is often shed, leaving viable tissue. Patients with severe frostbite are warned that many weeks of observation may be required before demarcation and the extent of tissue loss become apparent.

Whirlpool baths at 37° C 3 times a day followed by gentle drying, rest, and time are the best long-term management. No totally effective treatment for the long-lasting symptoms of frostbite (eg, numbness, hypersensitivity to cold) is known, although chemical or surgical sympathectomy may be useful for late neuropathic symptoms.