What is the difference between heat stroke and heat exhaustion?

Differences Between Heat Stroke and Heat Exhaustion

Heat stroke is a life-threatening emergency characterized by altered mental status and core temperature ≥104°F (40°C), while heat exhaustion is a moderate heat illness with normal mental status but symptoms of cardiovascular strain including weakness, dizziness, nausea, and headache.

Key Differences

Heat Exhaustion

• Definition: Moderate heat illness characterized by inability to maintain blood pressure and sustain adequate cardiac output 1
• Core Temperature: Up to 104°F (40°C) 1
• Mental Status: Normal (no central nervous system dysfunction)
• Primary Symptoms:
  • Weakness
  • Dizziness
  • Nausea
  • Syncope (fainting)
  • Headache
  • Fatigue
  • Heavy sweating 1

Heat Stroke

• Definition: Severe multi-system heat illness with central nervous system abnormalities 1
• Core Temperature: ≥104°F (≥40°C) 1
• Mental Status: Altered - including delirium, confusion, convulsions, or coma 1, 2
• Primary Symptoms:
  • All symptoms of heat exhaustion PLUS:
  • Central nervous system dysfunction (confusion, seizures)
  • Potential organ damage
  • Endotoxemia
  • Circulatory failure 1
  • Can lead to cardiac arrest, rhabdomyolysis, and death 1, 3

Management Differences

Heat Exhaustion Management

• Move to cool place
• Remove excess clothing
• Lie down
• Cool with water spray
• Drink cool fluids with electrolytes and carbohydrates 1
• Usually does not require emergency medical services

Heat Stroke Management

• Medical Emergency - Activate emergency services immediately 1
• Rapid cooling is critical:
  • Whole-body (neck-down) cold water immersion is preferred 1
  • Alternative cooling methods: ice packs, cold showers, ice sheets/towels 1
  • Continue cooling for 15 minutes or until neurological symptoms resolve 1
  • Target core temperature to cool to is 39°C (102.2°F) 1
• Requires hospitalization for monitoring complications 4

Risk Factors for Both Conditions

• Strenuous physical activity
• High environmental temperature and humidity
• Inadequate fluid intake
• Obesity
• Certain medications
• Lack of acclimatization to heat 4

Progression Risk

Heat exhaustion is serious because it can rapidly progress to heat stroke if not properly treated 1. The transition from heat exhaustion to heat stroke is marked by the development of central nervous system dysfunction.

Prognosis

• Heat Exhaustion: Good prognosis with proper treatment
• Heat Stroke: Survival directly related to speed of cooling; faster cooling = better survival 1. Mortality can be high if treatment is delayed 3.

Prevention

• Acclimatization to heat
• Adequate hydration
• Avoiding strenuous activity during extreme heat
• Wearing appropriate clothing
• Taking regular breaks in cool environments 4

Remember that recognizing the difference between these conditions is crucial, as heat stroke is a true medical emergency requiring immediate intervention to prevent death, while heat exhaustion, though serious, can typically be managed with supportive care.