Heat Stroke

Author: Teng Lu, MD

Emergency Medicine Resident

Stanford-Kaiser Emergency Medicine Residency

This post was peer reviewed.
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Case: It’s summer in the South Bay, California area, with temperatures averaging more than 80 °F. An elderly gentleman was brought in by emergency medical services (EMS) for altered mental status and hyperthermia. He was found sitting in the car in a parking lot where he had been for 2 hours, according to his family. Initial vital signs: temperature 107 °F, heart rate in the 140’s, respiratory rate >20, normotensive. His eyes opened to painful stimulation; he did not speak; and he localized to painful stimuli. Here are some pearls from that encounter.

Pearls:

• Heat exhaustion: defined as 101-104 °F, no central nervous system (CNS) dysfunction
  
• Heat stroke: defined as temperature >104 °F (40 °C), includes CNS dysfunction
  
• Categories: non-exertional (e.g., elderly, multiple co-morbidities), exertional (e.g., young athletes in the sun)
  
• Presentation: altered mental status (AMS), seizure, tachycardia, tachypnea (secondary to non-cardiogenic pulmonary edema), hypotension
  
• Differential diagnoses: neuroleptic malignant syndrome (NMS)/serotonergic syndrome, malignant hyperthermia, toxin exposure, hyperthyroidism including thyroid storm, meningitis/sepsis
  
• Evaluation: Foley catheterization, rectal temperature, electrocardiogram (ECG), chest X-ray, computed tomography (CT) of the head, CBC, chemistries, creatine kinase (CK), coagulation studies (to evaluate for disseminated intravascular coagulopathy), +/- toxicology lab studies

Management:

• Cold water immersion is the fastest way to cool (effective for young people, dangerous in elderly)
  
• ‘Evaporative cooling’ with mist and fans (however, this depends on the particular ED and how easily fans can be obtained.)
  
• Ice packs to groin, cold towels to face, cold normal saline
  
• No role for antipyretics (since hyperthermia is not due to a central process)
  
• IV benzodiazepines (for seizures, agitation, shivering)
  
• IV thorazine (some evidence for reducing shivering, only if NMS is NOT suspected)
  
• Supportive treatment; correct electrolytes

References: 

1. Atha WF. Heat-related illness. Emerg Med Clin North Am 2013 Nov;31(4):1097-108.
   
2. Bouchama A, Dehbi M, Chaves-Carballo E. Cooling and hemodynamic management in heatstroke: practical recommendations. Critical Care 2007;11(3):R54.
   
3. Bouchama A and Knochel JP. Heat Stroke. NEJM 2002;346:1978-1988. Online: http://www.nejm.org/doi/full/10.1056/NEJMra011089
   
4. Santelli J. Sullivan JM, Czarnik A, Bedolla J. Heat illness in the emergency department; keeping your cool. Emerg Med Pract 2014 Aug;16(8):1-21.