Cold Injury

The severity of cold injury depends on the temperature, duration of exposure, environmental conditions, amount of protective clothing, and the patient's general state of health. Hypothermia is discussed in a separate article.

Susceptibility to cold injury is increased by:¹

• Lower temperatures
• Infancy, elderly, malnutrition, exhaustion
• Immobilisation, e.g. fracture
• Open wounds
• Prolonged exposure
• Moisture
• Peripheral vascular disease
• Impaired cerebral function: e.g. alcohol, other sedatives, psychiatric illnesses²
• Hypoglycaemia, diabetes, hypothyroidism
• Nicotine or other vasoconstrictive agents
• Peripheral neuropathy, autonomic neuropathy, head injury, spinal cord damage
• Infection

• Frostnip: mildest form of cold injury. Initial pain, pallor and numbness of the affected area. It is reversible with rewarming and does not result in any tissue loss, unless the injury is repeated over many years, which causes fat pad loss or atrophy
• Frostbite: freezing of the tissue with microvascular occlusion and subsequent tissue anoxia. Some of the tissue damage may result from reperfusion during rewarming.
  • First degree: hyperaemia and oedema without skin necrosis
  • Second degree: large clear vesicle formation in addition to hyperaemia and oedema with partial-thickness skin necrosis
  • Third degree: full thickness with subcutaneous tissue necrosis, often with haemorrhagic vesicles
  • Fourth degree: full thickness and subcutaneous tissue necrosis, also involving muscle and bone with gangrene
• Non-freezing injury:
  • Trench foot: non-freezing injury of the hands or feet resulting from chronic exposure to wet conditions and and temperatures just above freezing
  • The entire foot may appear black but deep tissue destruction may not be present. Progression to hyperaemia within 24 to 48 hours causes an intense painful burning and dysaesthesia. Tissue damage causes oedema, blistering redness, bruising and ulceration.
  • Complications include local infection, cellulitis, lymphangitis or gangrene
  • Proper attention to foot hygiene can prevent the occurrence of most such injuries.
• Chilblain (pernio):³
  • Skin manifestation of chronic repetitive damp cold exposure or chronic dry cold exposure
  • Typically occurs on the face, tibial surface, or dorsum of the hands or feet, areas poorly protected or chronically exposed to the environment.
  • Pruritic, red purple skin lesions (papules, macules, plaques, or nodules)
  • Continued exposure leads to ulcerative or haemorrhagic lesions which progress to scarring, fibrosis, or atrophy with itching replaced by tenderness and pain.
  • Careful protection from further exposure and the use of antiadrenergics or calcium channel blockers are often helpful.

Tc-99m (Technetium 99) pertechnetate scintigraphy: sensitive and specific for tissue injury. Has been shown to give good correlation with ultimate extent of deep-tissue injury.⁴

• Early management of cold-injured patients includes:
  • Adhering to the ABCDEs (airway, breathing, circulation, disability, exposure and environment control) of resuscitation
  • Identifying the type and extent of cold injury
  • Measuring the patient's core temperature
  • Initiating a patient-care flow sheet
  • Initiating rapid rewarming techniques
  • Determining the patient's life or death status after rewarming
• Treatment should be immediate but rewarming should not be started if there is the risk of refreezing.
• Replace constricting, damp clothing by warm blankets. Give hot fluids to drink if possible.
• Place the injured part in circulating water at a constant 40 degrees C until the pink colour and perfusion return (usually within 20 to 30 minutes).
• Avoid dry heat and do not rub or massage the area.
• Rewarming can be very painful; adequate analgesia (IV narcotics).
• Intravenous fluids: rarely required but patients may be dehydrated
• Cardiac monitoring during rewarming

Local wound care of frostbite

• Elevating the injured area, which is left open to air.
• The affected tissue should be protected by a tent or cradle and pressure spots avoided.
• The wound should be kept clean and uninfected vesicles and blisters left intact for 7 to 10 days to provide protection.
• Tetanus prophylaxis depending on immunization status
• Systemic antibiotics: reserved for identified infections. Tobacco nicotine and other vasoconstrictive agents must be withheld. Weight-bearing is prohibited until oedema is resolved.
• Surgery: estimation of depth and extent of tissue damage are not usually accurate until demarcation is evident. Although the surgical management of frostbite involves delayed debridement 1 to 3 months after demarcation, recent improvements in radiological assessment of tissue viability has led to the possibility of earlier surgical intervention.⁵

When, combined with hypothermia or wound-related sepsis, frostbite may lead to death.

• Wound infection
• Tetanus
• Fluid sequestration in damaged tissues and diuresis may cause volume depletion²
• Hyperglycemia, acidosis⁶
• Dysrhythmias
• Gangrene
• Long-term sequelae of frostbite include:
  • Paraesthesias and sensory deficits, tremor
  • Hyperhidrosis or anhidrosis
  • Cracking of skin and loss of nails
  • Vasospasm, cold sensitivity
  • Joint stiffness
  • Premature closure of epiphyses in children; osteoporosis
  • Muscle atrophy