Heat-related illnesses are increasing, even in countries that are not normally linked to them, such as the UK. In this 10-minute clinic podcast episode, we look at heat exhaustion and heatstroke, why they are different conditions and how to recognise them. We also look at how they are treated, and when hospital admission should be considered.

• Heat exhaustion is the milder form of heat illness. The core temperature is normal or slightly elevated – 37°C to 40°C, compared with  over 40°C in heat stroke
• Classic heat stroke is due to passive exposure to severe environmental heat
• Exertional heat stroke is due to strenuous physical exercise, particularly in younger adults, athletes, and people who exert themselves in the heat
• The pathophysiology of heat stroke is complex. It includes the release of endotoxins and protein denaturation along with thermoregulatory failure. This can contribute to a systemic inflammatory response syndrome leading to multi-organ failure and death
• Heat exhaustion symptoms include cool skin, heavy sweating, feeling faint or dizzy, cramps and tiredness. Mental dysfunction is absent. Symptoms are the same in adults and children, although children can also become sleepy and floppy.
• Heatstroke symptoms include a history of exposure to severe environmental heat or strenuous physical exercise, central nervous system dysfunction, hyperthermia (>40°C) and dry, hot skin
• We should inform any patients at risk of heat stroke or heat exhaustion about the dangers of heat illness and of its symptoms
• This should include advising people who exercise or exert themselves to avoid high-exertion activities when exposed to heat or hot areas. They should also acclimatise with 1 to 2 hours per day of heat-exposed exertion for at least 8 days.
• Wetting the skin and clothes with cool water, and fanning the skin can aid in dissipating heat and may avert the onset of heat stroke.
• If heatstroke is suspected, call for immediate transport to the hospital as it is a medical emergency requiring urgent treatment.

References

• Heat stroke in adults – Symptoms, diagnosis and treatment | BMJ Best Practice
• Heat exhaustion and heatstroke – NHS (www.nhs.uk)
• Management of exertional heat stroke: a practical update for primary care physicians | British Journal of General Practice (bjgp.org)
• Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Heat Illness: 2019 Update – Wilderness & Environmental Medicine (wemjournal.org)

• Heat-Related Illnesses (aafp.org)