II. Epidemiology

  1. U.S. High school athletes
    1. Incidence: 1.6 cases per 100,000 athletes (9000 cases per year)
      1. Kerr (2013) Am J Prev Med 4491):8-14 [PubMed]
    2. Third leading cause of death in high school athletes
      1. Coris (2004) Sports Med 34(1): 9-16 [PubMed]
  2. U.S. Military
    1. Overall Incidence: 1.41 per 1000 person years (2163 cases in 2017)
    2. Heat StrokeIncidence: 0.38 per 1000 person years (464 cases in 2017)
    3. (2018) MSMR 25(4):6-10 [PubMed]
  3. U.S. Emergency Departments
    1. Heat Illness represented 5 per 10,000 summertime visits (in the years 2006 to 2010)
    2. Heat Exhaustion: 75% of cases
    3. Heat Stroke: 5.4% of cases
    4. Mortality: 0.07% of cases
    5. Hess (2014) Environ Health Prospect 122(11):1209-15 [PubMed]

III. Physiology

IV. Types: Heat Related Symptoms

  1. Heat Rash (Miliaria Rubra, Sweat Rash, Prickly Heat)
    1. Papules, Pustules or vessicles in in occluded areas of excessive sweating (esp. children)
  2. Heat Edema
    1. Benign swelling of feet, and ankles, and to a lesser extent hands
    2. Associated with salt or water retention from heat with cutaneous vasodilation
    3. Occurs in non-acclimitized patients (esp. elderly)
    4. Treated with leg elevation, Compression Stockings (avoid Diuretics)
    5. Resolves spontaneously over days with acclimitization or return to cooler environments
  3. Heat Syncope
    1. Dizziness or fainting immediately after completing Exercise and heat exposure
    2. Secondary to peripheral vasodilatation and venous pooling with secondary Postural Hypotension
    3. Seen in persons unaccustomed to extreme heat
    4. Move to cool, shaded environment, lie supine, and administer oral rehydration with salt containing solutions
    5. Consider Syncope differential diagnosis
      1. Syncope during Exercise is concerning (where as Syncope after Exercise is typically benign)
  4. Heat Cramps
    1. Painful Muscle Contractions or cramps (esp. larger Muscle groups)
    2. Most commonly affected Muscles include abdominal, quadriceps and gastrocnemius Muscle groups
  5. Heat Tetany
    1. See Tetany
    2. Results from Hyperventilation during strenuous activity
    3. Carpopedal Spasm with Paresthesias (including perioral)
    4. Differentiate from Heat Cramps which involves proximal large Muscle groups

V. Types: Exertional Heat Syndromes (spectrum of increasing severity)

  1. Heat Stress
    1. Core Temperature unchanged (<38 C or 100.4 F) and associated with decreased Exercise tolerance
  2. Heat Exhaustion
    1. Core Temperature rises above 38 C (100.4 F) associated with systemic symptoms
  3. Heat Stroke
    1. Core Temperature rises above 40 C (104 F) asssociated with Altered Level of Consciousness

VII. Management

  1. General Principles
    1. Rest (stop activity)
    2. Move to a cool, shaded area or indoor area
    3. Remove excessive clothing
    4. Initiate cooling (prompt cooling is imperative in Heat Stroke)
    5. Hydration
  2. Treat per degree of Heat Illness
    1. Heat Cramps
    2. Heat Exhaustion
    3. Heat Stroke

VIII. Associated Conditions

IX. Prevention

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Related Studies

Ontology: Thermal injury (C0332685)

Definition (SCTSPA) Lesión traumática debida a calor intenso
Definition (SNOMEDCT_US) Injury due to increased heat
Definition (CSP) damage inflicted on any part of an organism as the direct or indirect result of exposure to a high temperature, with or without disruption of structural continuity.
Concepts Injury or Poisoning (T037)
SnomedCT 161006
English heat injury, thermal injuries, heat injuries, thermal injury, injuries heat, injuries thermal, Heat injury, Thermal injury (morphologic abnormality), Thermal injury, Heat injury, NOS, Thermal injury, NOS
Spanish injuria por calor, injuria térmica, lesión por calor, lesión traumática térmica (anomalía morfológica), lesión traumática térmica

Ontology: Heat illness (C1456556)

Definition (MEDLINEPLUS)

Your body normally cools itself by sweating. During hot weather, especially with high humidity, sweating just isn't enough. Your body temperature can rise to dangerous levels and you can develop a heat illness. Most heat illnesses occur from staying out in the heat too long. Exercising too much for your age and physical condition are also factors. Older adults, young children and those who are sick or overweight are most at risk. Drinking fluids to prevent dehydration, replenishing salt and minerals, and limiting time in the heat can help.

Heat-related illnesses include

  • Heatstroke - a life-threatening illness in which body temperature may rise above 106![DEGREE SIGN]! F in minutes; symptoms include dry skin, rapid, strong pulse and dizziness
  • Heat exhaustion - an illness that can precede heatstroke; symptoms include heavy sweating, rapid breathing and a fast, weak pulse
  • Heat cramps - muscle pains or spasms that happen during heavy exercise
  • Heat rash - skin irritation from excessive sweating

Centers for Disease Control and Prevention

Concepts Injury or Poisoning (T037)
English Heat illness, Heat Illness
Spanish Enfermedad por calor
Dutch hitteaandoening
German Hitzekrankheit
Japanese ネッチュウショウ, 熱中症
Czech Tepelná nemoc
Portuguese Doença devido ao calor
Italian Malattia da calore
French Maladie due à la chaleur
Hungarian Hő betegség