Heat-related illnesses encompass a spectrum of disorders resulting from exposure to high temperatures and the body's inability to efficiently dissipate heat. These syndromes range from mild illnesses, such as heat edema, heat rash, and heat cramps, to more concerning manifestations such as exercise-associated collapse, heat exhaustion, and exertional rhabdomyolysis. The most severe and potentially life-threatening heat-related illnesses include exercise collapse associated with sickle cell trait, severe exercise-associated hyponatremia, and heat stroke. Common risk factors of heat-related illness are physical activity in high ambient temperatures, behavioral factors, lack of acclimatization, deconditioning, recent illness, inadequate hydration, predisposing medical conditions, use of certain drugs and supplements, and excessive clothing or equipment. Treatment of mild heat-related illness includes cessation of activity, removal of the patient from high temperatures, and oral hydration. Symptoms of heat exhaustion are nonspecific and may include the inability to continue physical activity, weakness, fatigue, headache, nausea, and vomiting. Management includes rest, hydration, and basic cooling measures. Heat stroke is a medical emergency requiring immersion in ice-cold water within 30 minutes to prevent significant morbidity and mortality. Diagnosis of severe exercise-associated hyponatremia and exercise collapse associated with sickle cell trait require a high index of suspicion because they can mimic heat stroke but require different treatments. Heat-related illnesses are largely preventable with proper acclimatization, adequate hydration, avoidance of physical activity in extreme temperatures, and promotion of population-based intervention programs, particularly during anticipated heat waves.
Heat-related illnesses encompass a spectrum of disorders from mild heat cramps to potentially fatal heat stroke. Excessive heat exposure and metabolic heat production exceeding the body's ability to regulate and dissipate heat increases the risk of heat-related illnesses.
Human-induced climate change has resulted in a sustained increase in mean global temperatures since the preindustrial era. Since 1982, the rate of temperature rise has accelerated to approximately 0.36°F (0.20°C) per decade, representing more than a threefold increase compared with earlier trends.1–3 A systematic review concluded that for every 1.8°F (1°C) rise in hot temperatures, or during heat waves, the risk of heat-related–illness morbidity increased by 18%, and mortality increased by 35%.4
SORT: KEY RECOMMENDATIONS FOR PRACTICE
| Clinical recommendation | Evidence rating | Comments |
|---|---|---|
| Patients who collapse with prolonged recovery (> 15 minutes), associated trauma, loss of consciousness during exercise, preceding cardiac symptoms, or cardiovascular risk factors should be medically cleared before resuming physical activity.15,27,28 | C | Clinical practice guidelines, expert consensus |
| Immersion in ice-cold water is the recommended treatment for heat stroke. It improves survival rates when core body temperature is rapidly lowered below 102.2°F (39°C) within 30 minutes of recognition. 9,15,19,38–40 | B | Clinical practice guideline summaries based on retrospective trials and small case series |
| Dantrolene (Dantrium) or other antipyretic agents are not recommended to reduce core body temperature in the treatment of heat stroke.9,15,41,42 | C | Systematic review, clinical practice guidelines, expert consensus |
| A progressive increase in exercise intensity and duration (starting at 1 hour per day with a gradual increase to 2 hours per day) over 7 to 14 days is recommended to reduce the risk of heat-related illnesses.9,15,28 | C | Clinical practice guidelines, expert consensus |
A = consistent, good-quality patient-oriented evidence; B = inconsistent or limited-quality patient-oriented evidence; C = consensus, disease-oriented evidence, usual practice, expert opinion, or case series. For information about the SORT evidence rating system, go to https://www.aafp.org/afpsort.
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