Hyperpyrexia (heat stroke)

• Heat stroke is a clinical constellation of symptoms that include a severe elevation in body temperature which typically, but not always, is greater than 40 degrees C
  • there must be clinical signs of central nervous system dysfunction that may include ataxia, delirium, or seizures, in the setting of exposure to hot weather or strenuous physical exertion (1)
    
• hyperpyrexia is the high fever and collapse due to failure of the heat regulation. If the rectal temperature is over 42 degrees C(108 degreesF), irreversible brain damage can occur
  • heat stroke is a life-threatening injury requiring neurocritical care, and there have been at least 3332 deaths attributed to heat stroke from 2006 to 2010 in the USA (2)
    • regarding heat stroke, 28-day and 2-year mortality rates have been reported to be 58 and 71%, respectively
    • the number of deaths from heat stroke has been reported to increase due to climate change
      • by the 2050s, heat stroke-related deaths are expected to rise by nearly 2.5 times the current annual baseline of approximately 2000 deaths
        
        
• Bouchama has defined heat stroke as:
  • a core body temperature that rises above 40 degrees C, accompanied by hot dry skin and central nervous system abnormalities, such as delirium, convulsions, or coma
  • heat stroke results from exposure to a high environmental temperature or from strenuous exercise
  • has proposed an alternative definition of heat stroke on the basis of its pathophysiology, stating that heat stroke is a form of hyperthermia associated with a systemic inflammatory response that leads to a syndrome of multiorgan dysfunction, predominantly encephalopathy
    
    
• heat stroke often occurs in children who have been outside on a really hot day at home without adequate protective clothing or when on holiday abroad
  
  
• heat stroke occurs more commonly in children with cystic fibrosis than other children
  
  
• heat stroke has been classified into two groups according to the presence or absence of exertion:
  • exertional heat stroke develops in able-bodied individuals, such as athletes, soldiers, or laborers, and performing rigorous physical activities
  • nonexertional heat stroke can develop during low-level physical activities among elderly, ambulatory individuals with comorbidities including obesity, diabetes, hypertension, heart disease, renal disease, dementia, and alcoholism

Reference:

• Leon LR, Bouchama A. Heat stroke. Compr Physiol. 2015 Apr;5(2):611-47.
  
• Hifumi T, Kondo Y, Shimizu K, Miyake Y. Heat stroke. J Intensive Care. 2018;6:30. Published 2018 May 22. doi:10.1186/s40560-018-0298-4
• Bouchama A, Knochel JP. Heat stroke. N Engl J Med. 2002 Jun 20;346(25):1978-88. doi: 10.1056/NEJMra011089. PMID: 12075060.
• Morris A, Patel G. Heat Stroke. In: StatPearls. StatPearls Publishing, Treasure Island (FL); 2021. PMID: 30725820.