1. Heat oedema

Oedema of the hands and feet is transient and resolves spontaneously.

Diuretic treatment has no role to play in the management of heat oedema.

2. Heat syncope

Heat syncope results from volume depletion and peripheral vasodilatation. It is important to exclude other causes of syncope before attributing a syncopal episode to heat exposure.

Patients are removed to a cooler environment. Rehydration with oral or intravenous fluids usually produces a marked improvement.

Patients with reduced vasomotor tone and fixed cardiac output are more susceptible to heat syncope.

3. Heat cramps

Painful involuntary muscle contractions can occur in association with prolonged exertion. Large muscle groups are often involved.

Heat cramps are usually self-limiting.

Management simply involves cooling, rest, analgesia and rehydration with oral fluids or intravenous saline.

4. Heat exhaustion

Heat exhaustion is a systemic disorder. Patients complain of headache and nausea. Vomiting is common and is often associated with a generalised weakness.

Patients are tachycardic and tachypnoeic and often sweat profusely. Orthostatic hypotension may be present. Body temperature is elevated but usually below 40.0°C. Patients are water- and salt-depleted.

5. Heat stroke

This is the worst form of heat-related illness and represents complete thermoregulatory failure. The classic presentation involves three main findings:

  • Core body temperature above 40.0°C
  • Encephalopathy
  • Anhydrosis

Clinical findings vary. Sweating has been reported in cases of heat stroke and core temperature may have fallen below 40.0°C during transfer to hospital.

The key distinguishing factor of heat stroke is a systemic inflammatory response. This leads to multi-organ problems, with encephalopathy predominating [6].

The presence of neurological problems and hot, dry skin help distinguish heat stroke from heat exhaustion.