Cold injuries

Types

• Non-freezing cold injuries
  • Trench foot
  • Chillblains/Pernio
  • Panniculitis
  • Cold urticaria
• Freezing injuries
  • Frostbite

Trench foot/Immersion foot

• Direct injury to soft tissue from prolonged cooling and wet conditions
• Peripheral nerves are the most sensitive
• History – Tingling, numbness
• Examination
  • Pale, mottled, anaesthetic, pulseless and immobile with no immediate changes with rewarming
  • Hyperaemic phase begins hours after rewarming with severe burning pain and reappearance of proximal sensation
  • Perfusion returns over 2-3 days with oedema, bullae and worsening hyperaemia
  • Tissue sloughing and gangrene may develop in severe cases
  • Hyperhidrosis and cold sensitivity can persist for years
• Treatment
  • Supportive, oral prostaglandins, warm, dry bandaging, elevated and monitored for infection

Chillblains/Pernio

• Mild but uncomfortable inflammatory lesions of skin caused by long-term intermittent exposure to damp, non-freezing ambient temperature
• Typically toes, hands, ears and lower legs
• Chillblains are seen in women and children mostly
• Young females with Raynaud’s or SLE are at greatest risk
• Low BMI increases risk
• History – Tingling, numbness of affected tissues, pruritis and burning paraesthesia
• Examination – Within 12-24 hours get localised oedema, erythema, cyanosis, plaques, nodules, ulcerations, vesicles and bullae
  • Rewarming can form tender blue nodules that persist for days
• Management
  • Rewarm, gently bandage and elevate
  • Nifedipine and topical corticosteroids are effective

Panniculitis

• Mild necrosis of subcutaneous fat after prolonged exposure to above freezing cold
• Seen in children (popsicle panniculitis on cheeks) and on thighs/buttocks of young women in equestrian activities
• Adipose fibrosis can cause cosmetic defects
• No effective treatment exists

Cold urticaria

• Hypersensitivity to cold air or water, which can rarely lead to anaphylaxis
• Young adults and children most at risk, especially if atopic
• Treatment
  • Antihistamines with higher than usual dosing
  • Leukotriene receptor antagonists
  • Capsaicin
  • Adrenaline if anaphylaxis

Frostbite

• Risk factors
  • Military
  • Winter sports
  • Outdoor workers
  • Elderly
  • Homeless
  • Drug or alcohol abuse
  • Psychiatric disorders
  • Boys > girls
  • Rates of injury increase when temp <-12 and wind >10mph
  • Rates of injury increase at altitude >5182m
  • Frostbite can develop in 2-3 seconds of touching a surface <-15 degrees
  • Use of protective ointments increases the risk of frostbite
  • PVD, Raynaud’s, diabetes, peripheral neuropathy, vasoconstrictive medications

• Pathophysiology
  • Tissue freezing along is not sufficient to cause cell death (need thawing)
  • Depth of tissue freezing depends on temperature, duration of exposure and velocity of freezing
  • Endothelial damage at point of thaw is likely critical event
    • Arachidonic acid cascade occurs with vasoconstriction, platelet activation, leukocyte sludging and erythrostasis resulting in thrombosis, ischaemia, necrosis and dry gangrene
  • Three zones
    • Zone of coagulation – Distal, irreversible
    • Zone of hyperaemia – Most superficial, proximal, the least damage and recovers within 10 days without treatment
    • Zone of stasis – Middle ground with severe, but potentially salvageable tissue
  • The least to most sensitive tissues are:
    • Cartilage, ligament, blood vessel, cutis, epidermis, bone, muscle, nerve and bone marrow
    • Head > hands > feet

• Clinical features
  • First-degree (frostnip)
    • Partial skin freezing, erythema, numbness, central pallor, lack of blisters and skin desquamation days later
  • Second-degree
    • Full-thickness skin freezing, substantial oedema, erythema and clear blisters within 6-24 hours, extending to end of digit and usually desquamate to form black eschars over several days
    • Good prognosis
  • Third-degree
    • Damage into the subdermal plexus. Haemorrhagic blisters with skin necrosis and blue-grey discolouration of skin
    • Extremity feels like block of wood and then burns, throbs and shotting pain. Poor prognosis
  • Fourth-degree
    • Extension into subcutaneous tissue, muscle, bone and tendon
    • Minimal oedema, mottled, non-blanching cyanosis and deep, dry, black eschar
    • Vesicles arise late, if at all, and do not extend to digit tips. Extremely poor prognosis

• Treatment
  • Prevention of further cold injury, hypothermia and dehydration
  • Remove wet and constrictive clothing, dry and warm
  • Do not heat the frozen area as dry heat will worsen injury
  • Do not attempt rewarming until risk of refreezing is eliminated
  • Analgesia, immobilise and elevate frozen extremities
  • Place injured extremity in gently circulating water at 37-39 degrees for 20-30 minutes until extremity is pliable and erythematous
  • Can rewarm faces with moistened compresses soaked in warm water
  • Anticipate severe pain with rewarming and treat with opioids
  • Debatable whether to deroof clear blisters
  • Haemorrhagic blisters should NOT be de-roofed
  • Treat all blisters with topical aloe vera cream q6h as combats the arachidonic acid cascade
  • Separate affected digits with cotton wool and wrap with dry gauze
  • Tetanus booster required
  • Thrombolysis after rapid rewarming seems to reduce amputation rates
  • Prophylactic Penicillin G 500 000 U IV q6h seems to prevent infection
    • Topical bacitracin may be as effective
    • Topical silver sulfadiazine may be helpful
  • Oral ibuprofen can also combat the arachidonic acid cascade
  • Prolonged sympathetic blockade with bupivacaine may improve blood flow to hand, relieve pain and speed recovery
  • Continuous epidural anaesthesia may relieve peripheral vasospasm and prevent retrograde arterial and venous thrombosis
  • Heparin and hyperbaric oxygen of no clear value
  • Early surgical intervention is not indicated as impossible to assess depth of frostbite in early stages and mummified carapace protects underlying healing tissue
  • Limited early escharotomy may be indicated if limiting perfusion or ROM

• Sequelae
  • Hypersensitivity to cold, pain and ongoing numbness
• Disposition
  • Superficial local frostbite may allow discharge to adequate social environment
  • Clear self-care guidelines and close follow-up with local burns centre or plastic surgery
  • Avoid smoking and drinking while healing

Last Updated on November 23, 2021 by Andrew Crofton