HEAT STROKE IN ADULTS

BMJ APRIL2022

Last updated: 13 Apr 2022
Summary
Heat stroke is a medical emergency. Clinical features include a core body temperature >40°C and central nervous system dysfunction (e.g., altered level of consciousness ranging from confusion to coma [encephalopathy], seizures) in the context of passive exposure to severe environmental heat (classic heat stroke) or strenuous exercise (exertional heat stroke).

Use a rectal thermometer to measure core body temperature and monitor continuously. In practice, consider using an oesophageal probe in intubated patients.

Start rapid active cooling immediately, based on clinical suspicion regardless of degree of hyperthermia and measuring technique. Aim to achieve a target temperature of no less than 39°C. Stop cooling once this temperature is reached.

Cold or ice water immersion is the preferred method for patients with exertional heat stroke. Use wetting and fanning the skin in patients with classic heat stroke and consider wetted ice packs or chemical cold packs as adjunctive cooling.

Patients are at risk of multi-system organ failure, so careful monitoring is essential even after return to normothermia.

Definition
Heat stroke is defined as a core temperature >40°C with central nervous system dysfunction (e.g., altered level of consciousness ranging from confusion to coma [encephalopathy], seizures).[1] Heat stroke is generally divided into classic heat stroke (due to passive exposure to severe environmental heat) and exertional heat stroke (due to strenuous physical exercise).[1]

Heat exhaustion is a mild to moderate heat illness.[1] The patient presents with a normal or slightly elevated core temperature (37°C to 40°C), mild neurological symptoms (e.g., intense thirst, weakness, anxiety, dizziness, syncope), and an intact mental status.[1][2] If untreated, heat exhaustion can progress to heat stroke. Heat stroke, however, can occur without preceding heat exhaustion.[1]

Key diagnostic factors
history of exposure to severe environmental heat or strenuous physical exercise
central nervous system dysfunction
hyperthermia (>40°C)
anhidrosis

Other diagnostic factors
intense thirst (heat stroke or heat exhaustion)
weakness (heat stroke or heat exhaustion)
anxiety (heat stroke or heat exhaustion)
dizziness (heat stroke or heat exhaustion)

Risk factors
older age
impaired cognition
patients unable to care for themselves

1st investigations to order
rectal temperature
FBC
liver function tests
renal function tests

G Mohan.