Too Hot to Handle: Heat Emergencies

Heat stroke is a clinical diagnosis defined by hyperthermia plus central nervous system dysfunction, not by a single thermometer cutoff alone. In emergency medicine, heat illness spans cramps and syncope through heat exhaustion and life-threatening exertional or non-exertional heat stroke, with rapid cooling and safe disposition doing most of the work.

Recognition and Differential of Heat Illness

• Clinical diagnosis over temperature: Heat-related illness is diagnosed by presentation rather than a number alone; hyperthermia with altered mental status should keep heat stroke high on the differential even when other causes are possible.
• Broad secondary hyperthermia differential: Not all hot patients have environmental heat illness, so infection, drugs or toxins, endocrine disease, and neurologic catastrophe still need parallel consideration in the altered, hyperthermic patient.
• Spectrum of heat presentations: Heat cramps, syncope, edema, exhaustion, and heat stroke sit on a clinical spectrum, with CNS dysfunction marking the jump from dehydration-type illness to true heat stroke.
• Exertional versus classic forms: Non-exertional heat stroke often affects older patients during heat waves and carries higher mortality, while exertional heat stroke classically presents in younger sweaty patients with profound dehydration.
• Hidden parallel emergencies: Prolonged heat exposure may be the consequence rather than the cause, so falls, stroke, myocardial infarction, and infection can coexist and change the whole management plan. We get into those bedside distinctions in the episode.

Cooling Strategies and Disposition

• Cooling is the treatment: Heat stroke management is fundamentally about active and passive cooling; antipyretics do not help because hyperthermia is not a hypothalamic set-point problem.
• Passive cooling basics: Shade, airflow, loosened clothing, reduced ground conduction, and hydration all improve the body's own heat exchange and should start immediately while the team mobilizes more aggressive measures.
• Cold water immersion advantage: Cool water immersion is the fastest noninvasive option because water conducts heat about 24 times better than air, making it a high-yield strategy for severe exertional heat stroke.
• Evaporative and adjunct methods: Evaporative cooling, chemical cold packs, commercial devices, and chilled IV fluids all help, while benzodiazepines can reduce shivering or agitation that interferes with cooling. We walk through the practical setup in the chapter.
• Complications and safe disposition: Heat stroke can declare delayed transaminitis, DIC, rhabdomyolysis, and renal failure, so disposition hinges on end-organ risk and whether the patient can actually reach a safe cool environment after discharge.

References:

1. Savioli G, Zanza C, Longhitano Y, et al. Heat-Related Illness in Emergency and Critical Care: Recommendations for Recognition and Management with Medico-Legal Considerations. Biomedicines. 2022;10(10):2542. Published 2022 Oct 12. PMID: 36289804
2. American College of Sports Medicine, Armstrong LE, Casa DJ, et al. American College of Sports Medicine position stand. Exertional heat illness during training and competition. Med Sci Sports Exerc. 2007;39(3):556-572. PMID: 17473783
3. Zhang Y, Davis JK, Casa DJ, Bishop PA. Optimizing Cold Water Immersion for Exercise-Induced Hyperthermia: A Meta-analysis. Med Sci Sports Exerc. 2015;47(11):2464-2472.PMID: 25910052
4. Rublee C, Dresser C, Giudice C, Lemery J, Sorensen C. Evidence-Based Heatstroke Management in the Emergency Department. West J Emerg Med. 2021;22(2):186-195. Published 2021 Feb 26. PMID: 33856299
5. Epstein Y, Yanovich R. Heatstroke. N Engl J Med. 2019;380(25):2449-2459. PMID: 31216400