Overview

•  Spectrum
  • Cramps
  • Syncope
  • Exhaustion
  • Stroke
• Physiology of cooling
  • Radiation: body warmer than environment, heat radiates away
  • Evaporation: environment warmer than body, sweat promotes heat exchange, affected by ambient humidity

Heat cramps

• Mechanism: fluid/electrolyte depletion resulting in muscle cramps
• Management: IVF, electrolyte repletion, cooling

Heat syncope

• Mechanism: vasodilation resulting in hypotension
• Management: IVF, cooling, rule out alternative etiologies

Heat exhaustion

• Mechanism: similar to heat cramps
• Symptoms: influenza-like, headache, fatigue, dizziness, nausea, normal mental status distinguishes from heat stroke
• Findings: temperature <40°C
• Management: IVF, cooling

Heat stroke

• Mechanism: similar to heat cramps
• Symptoms: prodrome of heat exhaustion
• Signs: AMS, ataxia, seizure
• Findings: temperature >40°C
• Mortality: 30-80%
• Labs: AST/ALT, coagulopathy, DIC, rhabdomyolysis, ATN/AKI
• CXR: pulmonary edema
• Types
  • Classical: elderly, dry skin, mild dehydration, increased mortality
  • Exertional: young athlete, diaphoretic, increased morbidity (organ failure)
• Management
  • Evaporative cooling
  • Ice packs to large vessels
  • GI lavage
  • Liberal intubation
  • Benzodiazepines or thorazine for inappropriate thermogenesis (shivering)
  • Halt cooling at 40°C