• Risk factors
  • Extremes of age
  • Behavioral: psychosis, intoxication
• Types
  • Chillblains
  • Immersion foot
  • Frostnip
  • Frostbite
  • Generalized

Chilblains

• Findings: red/white plaques on extremities
• Symptoms: pruritus, pain
• Management: supportive (gentle warming), topical corticosteroids, consider nifedipine

Immersion foot (trench)

• Mechanism: prolonged immersion in non-freezing water, vasoconstriction leads to ischemia/necrosis
• Findings: pale, mottled skin, paresthesia
• Management: supportive, drying and rewarming
• Complications: gangrene

Frostnip

• Retrospective distinction from frostbite after rewarming if no tissue loss

Frostbite

• Mechanism: extracellular then intracellular crystal formation (mechanistically similar to crush injury)
• Reperfusion: cellular injury triggers cytokine release upon reperfusion, results in microvascular thrombosis and tissue ischemia/necrosis
• Classification: grades I-II superficial to dermis, grades III-IV involve subcutaneous tissue to bone
• Management
  • Rapid rewarming (immersion in warm water at 41°C)
  • Tdap
  • Debridement of clear blisters

Generalized

• Causes
  • Exposure
  • Metabolic (adrenal, thyroid, hypoglycemia)
  • Sepsis
• Grading
  • Mild (32.2-35°C)
    • Findings: excitation, tachycardia, hypertension, shivering thermogenesis
  • Moderate (30-32.2°C)
    • Findings: ataxia, AMS, bradycardia, hypotension, bradypnea
    • ECG:  Osborn wave
  • Severe (<30°C)
    • Complications
      • Increased risk of arrhythmia (bradycardia, slow atrial fibrillation, ventricular fibrillation, asystole)
      • Irritable myocardium
      • Decreased enzymatic activity
        • Renal: cold diuresis
        • Heme: coagulopathy (hidden on labs as blood rewarmed prior to testing)
        • Metabolic: hyperglycemia as insulin ineffective
    • Management
      • Ventricular fibrillation: attempt one shock, then focus on rewarming if ineffective
      • Goal >30°C

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