A recent article published in the American Family Physician discussed that heat-related illnesses comprise a spectrum of syndromes resulting from disruption of thermoregulation in people exposed to high environmental heat. Symptoms range from heat edema and exercise-associated muscle cramps to exercise-associated collapse, heat exhaustion and life-threatening heat stroke. Athletes, outdoor laborers and military personnel are at greatest risk for heat-related illnesses. Additionally, several intrinsic and extrinsic factors increase the risk, including – medical conditions, environmental factors, medication use and inadequate acclimatization.

The authors stated that early identification and treatment are effective in preventing adverse outcomes in these conditions. Management of the mildest forms of heat-related illness—for instance, heat edema, exercise-associated muscle cramps—is largely supportive and sequelae are rare.

This article further elaborated that heat exhaustion is characterized by cardiovascular hypoperfusion and a rectal core temperature up to 104°F without central nervous dysfunction. For these patients, mild cooling, rest and hydration are recommended. While heat stroke is a medical emergency in which patients present with rectal core temperature of 105°F or greater, multiorgan damage and central nervous dysfunction. Ice water or cold-water immersion should be advised. Moreover, patients adequately cooled within 30 minutes have excellent outcomes. However, patients with heat stroke generally require hospitalization to monitor for medical complications despite rapid cooling. People diagnosed with heat stroke or severe heat-related illness should refrain from physical activity for at least seven days after release from medical care, then gradually begin activity over two to four weeks. Acclimatization, adequate hydration, and avoidance of activities during extreme heat are the most effective measures to reduce the incidence of heat-related illnesses.

Most heat-related illnesses can be avoided or minimized. The National Athletic Trainers’ Association and the American College of Sports Medicine endorse preventive recommendations for the prevention of heat-related illnesses, that include – acclimatization; adequate hydration; wearing loose-fitting, light-colored clothing; and avoidance of activities during extreme temperatures.

• When avoidance is not possible, frequent water breaks, scheduled rest and recovery cycles, and close monitoring are recommended.
• Supervisory personnel, such as coaches and military trainers, should be familiar with symptoms of heat-related illnesses and first-aid treatment.
• Medical systems in regions where the risk of heat-related illnesses is high are encouraged to use evidence-based standards in the care of these patients – including prehospital recognition and management, emergency department treatment and inpatient treatment of complications.
• Older patients are at increased risk of non-exertional heat stroke, particularly during periods of extreme temperatures. Family or caretakers are encouraged to visit often, ensure adequate water intake, verify operable air conditioning and assess for signs or symptoms of heat-related illness.
• Comorbid medical conditions, medication use and lack of air conditioning compound the problem.
• Cities should create contingency plans for heat waves – including provision of shelters, providing established water sources and optimizing medical care for homeless persons.
• Wet bulb globe temperature meters are affordable and easily available. These devices take into account temperature, humidity and direct radiant sunlight to measure environmental heat stress, allowing trainers to plan events to avoid excessive heat.
• Heat index charts can also be used, but these are calculated for shaded areas—thus, limiting their usefulness when activities are conducted in direct sunlight.

Summary of Recommendations for Clinical Practice:

• Ice water and cold-water immersion are the most effective cooling modalities in the treatment of heat stroke.
• Patients with heat stroke should be cooled to a core body temperature of 101°F (38.3°C) within 30 minutes after recognition of symptoms.
• Rectal temperature is the recommended method for obtaining core body temperature to assist in the diagnosis of heat stroke.
• Ensuring adequate acclimatization, physical fitness and hydration, and assessing wet bulb globe temperature or heat index before outdoor activity or work reduces the risk of heat-related illnesses.

Source: American Family Physician. 2019;99(8):482-489.