Hypothermia

posted in Environmental Disorders on by
SimWars

This post is part of a series developed in preparation for participation in ACEP SimWars. It contains a review of several prominent emergency medicine topics which may be relevant for board preparation. Unless otherwise cited, content is based on HippoEM videos.

Overview

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

Hypothermia

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