Frostbite

Key Features

Essentials of Diagnosis

• Injury is due to freezing and formation of ice crystals within tissues

General Considerations

• Localized hypothermia, vasoconstriction, and slowed metabolism occur as temperature falls below 25°C, although oxygen demand may increase if activity continues

• Once tissue is frozen it becomes pain free

• Most tissue destruction follows the reperfusion of the frozen tissues, with damaged endothelial cells and progressive microvascular thrombosis resulting in further tissue damage

Clinical Findings

Symptoms and Signs

Mild cases

• Only the skin and subcutaneous tissues are involved

• The symptoms are numbness, prickling, itching, and pallor

Severe cases

• With increasing severity, deep frostbite involves deeper structures

• There may be paresthesia and stiffness

• Thawing causes tenderness and burning pain

• Skin is white or yellow, loses its elasticity, and becomes immobile

• Edema, hemorrhagic blisters, necrosis, and gangrene may appear

Diagnosis

Imaging Studies

• MRI with magnetic resonance angiography and technetium scintigraphy can assess the degree of involvement and distinguish viable from nonviable tissue

Treatment

Medications

• Administration of an intra-arterial thrombolytic administration within 24 hours of exposure has resulted in improved tissue perfusion and has reduced amputation

• The rate of tissue salvage decreases with every hour of delay from rewarming to thrombolytic therapy

• Anti-infective measures

  • Tetanus prophylaxis status must be verified and updated as needed; frostbite increases susceptibility

  • Infection risk may be reduced by aseptic wound care and protection of skin blebs from physical contact

  • Wounds should be kept open and allowed to dry before applying dressings

  • Nonadherent sterile gauze and fluffy dressing should be loosely applied to wounds and cushions used for all areas of pressure

  • Antibiotics should not be administered empirically

  • Systemic antibiotics are reserved for deep infections not responding to local wound care

Therapeutic Procedures

• Treat associated systemic hypothermia (see Hypothermia)

• Monitor fluids and electrolytes

• Superficial frostbite (frostnip) of extremities

  • In the field, apply firm steady pressure with warm hand (without rubbing)

  • Place fingers in the armpits

  • Remove footwear, dry the feet, rewarm, cover with adequate dry socks or other protective footwear

• Frostbite

  • If there is a possibility of refreezing, frostbitten part should not be thawed, even if it means prolonged walking on frozen feet; refreezing increases tissue necrosis

Rewarming

• Rapid thawing at temperatures slightly above body heat may significantly decrease tissue necrosis and reverse the tissue crystallization

• Immerse the frozen extremity for several minutes in a moving-water bath heated to 40–42°C until the distal tip of the part being thawed flushes (water ...