Abnormally high body temperature. A rapid rise of temperature to dangerous levels – known as malignant hyperthermia – may be precipitated by general ANAESTHESIA but the condition is rare (1:50,000 operations) and relates to a genetic susceptibility. The anaesthetic is stopped and icepacks are used to cool the patient. Pure oxygen and intravenous sodium chloride are also administered.

Hyperthermia is also the name given to the treatment of disease by the artificial production of FEVER. This can be achieved by various methods, such as radiation heat cabinets boosted with radio frequency (RF); immersion in a hot wax bath; heated suits or blankets; techniques using electromagnetic waves (e.g. RF, MICROWAVES); and ULTRASOUND of appropriate frequencies. Hyperthermia is sometimes of help as an adjunct to surgery, CHEMOTHERAPY, or RADIOTHERAPY in the treatment of cancer.