From the Guidelines
Heat exhaustion is diagnosed when a person develops symptoms after exposure to high temperatures, typically during physical activity or prolonged heat exposure, with a core body temperature between 37°C and 40°C (98.6°F to 104°F), accompanied by symptoms such as heavy sweating, pale or clammy skin, rapid but weak pulse, nausea or vomiting, muscle cramps, fatigue, weakness, headache, dizziness, and fainting. The diagnostic criteria for heat exhaustion include a combination of these symptoms, with mild confusion possibly present, but severe mental status changes suggesting heat stroke instead 1. Diagnosis is clinical and based on symptoms and history of heat exposure, without requiring specific laboratory tests. Heat exhaustion occurs when the body's cooling mechanisms become overwhelmed, leading to dehydration and electrolyte imbalances as sweat losses increase.
Some key points to consider in the diagnosis of heat exhaustion include:
- Core body temperature: between 37°C and 40°C (98.6°F to 104°F) 1
- Symptoms: heavy sweating, pale or clammy skin, rapid but weak pulse, nausea or vomiting, muscle cramps, fatigue, weakness, headache, dizziness, and fainting 1
- History of heat exposure: typically during physical activity or prolonged heat exposure 1
- Clinical diagnosis: based on symptoms and history, without requiring specific laboratory tests 1
Treatment involves immediate cooling, moving to a cooler environment, removing excess clothing, applying cool compresses, drinking cool fluids with electrolytes, and rest. If symptoms don't improve within 30-60 minutes with these measures, or if vomiting prevents oral rehydration, medical attention should be sought as heat exhaustion can progress to life-threatening heat stroke if left untreated 1. According to the most recent guidelines, first aid providers should move the individual from the hot environment, remove excess clothing, limit exertion, and provide cool liquids if the person is able to swallow 1.
From the Research
Diagnostic Criteria for Heat Exhaustion
The diagnostic criteria for heat exhaustion include a range of signs and symptoms that can develop suddenly or over time. Some of the key indicators are:
- Cardiovascular hypoperfusion 2
- Rectal core temperature up to 104°F without central nervous dysfunction 2
- Malaise, vomiting, and confusion 3
- Flushed face, hyperventilation, headache, dizziness, nausea, tingling arms, piloerection, chilliness, incoordination, and confusion 4
- Unsteady gait and confusion 5
Risk Factors
Certain individuals are more vulnerable to heat exhaustion, including:
- Children 6, 3
- Older adults 6, 3
- Those with chronic disease 6
- Athletes, outdoor laborers, and military personnel 2
- People who are unacclimatized, unfit, or hypohydrated 4
Prevention and Treatment
Prevention and treatment of heat exhaustion involve:
- Increasing public awareness of the risks associated with exposure to high temperatures and prolonged exercise 6
- Taking regular breaks to cool down and rehydrate 4
- Wearing lightweight, loose-fitting clothing and staying in cool, well-ventilated areas 4
- Using cooling strategies such as cold showers, wet towels, or ice water immersion 6, 2
- Replacing fluids and electrolytes as needed 3, 2