A condition resulting from environmental temperatures which are too high for compensation by the body's thermo-regulatory mechanism(s). It is characterised by an extremely high body temperature (hyperpyrexia), nausea, headache, thirst, confusion, and dry skin. If untreated, COMA and death ensue. The occurrence of heat stroke is sporadic: whereas a single individual may be affected (occasionally with fatal consequences), his or her colleagues may remain unaffected. Predisposing factors include unsatisfactory living or working conditions, inadequate acclimatisation to tropical conditions, unsuitable clothing, underlying poor health, and possibly dietetic or alcoholic indiscretions. The condition can be a major problem during pilgrimages – for example, the Muslim Hadj. Four clinical syndromes are recognised:
is characterised by fatigue, giddiness, and temporary loss of consciousness. It is accompanied by HYPOTENSION and BRADYCARDIA; there may also be vomiting and muscular cramps. Urinary volume is diminished. Recovery is usual.
is characterised by increasing weakness, dizziness and insomnia. In the majority of sufferers, sweating is defective; there are few, if any, signs of dehydration. Pulse rate is normal, and urinary output good. Body temperature is usually 37.8–38.3 °C.
(usually in the legs, arms or back, and occasionally involving the abdominal muscles) are associated with hard physical work at a high temperature. Sweating, pallor, headache, giddiness and intense anxiety are present. Body temperature is only mildly raised.
is heralded by energy loss and irritability; this is followed by mental confusion and diminution of sweating. The individual rapidly becomes restless, then comatose; body temperature rises to 41–42 °C or even higher. The condition is fatal unless expertly treated as a matter of urgency.
With the first two syndromes, the affected individual is best removed immediately to a cool place, and rehydrated with sodium containing fluids – intravenously in a severe case. The fourth syndrome is a medical emergency. Standard recommendations are that the patient should be placed in the shade, stripped, and drenched with water. He or she should be wrapped in a sheet soaked in cool water and fanned continuously. When rectal temperature has fallen to 39 °C, the patient is wrapped in a dry blanket. Immediately after consciousness returns, normal saline should be given orally; this usually provokes sweating. Convalescence may be protracted and the patient should be repatriated to a cool climate. Prophylactically, personnel intended for work in a tropical climate must be very carefully selected. Adequate acclimatisation is advisable, severe physical exertion avoided if possible for some weeks and light clothes worn. Those performing hard physical work at a very high ambient temperature should receive sodium chloride supplements. Attention to ventilation and air-conditioning is essential.