Caffeine the key to hyperthermia test

Patients at risk from an adverse reaction to anesthesia could be pinpointed before undergoing the potentially dangerous procedure thanks to a simple caffeine injection.

German scientists writing in the current issue of The Lancet​ said that people who suffered from malignant hyperthermia - a potentially fatal condition by muscle rigidity, an increase in metabolism and a sharp rise in body temperature - also reacted to an injection of caffeine. A control group who were not susceptible to the condition showed no such reaction.

If the technique is shown to work in a much larger clinical trial, it could revolutionise the way in which malignant hyperthermia is detected. The injection is a far simpler way of testing for the problem than the current method, a muscle biopsy. An alternative method is to test for a certain genetic mutation, but this only picks up 20 to 40 per cent of cases.

Dr Martin Anetseder and colleagues at the University of Wurzberg explained that the condition is caused by the muscle fibres releasing calcium in large quantities, in turn causing excess carbon dioxide production. Caffeine has already been shown to promote the release of calcium from muscle in sufferers of malignant hyperthermia, and Anetseder's team therefore decided to look at whether an injection of caffeine into a patient's buttock muscle would briefly increase carbon dioxide pressure in that area.

Twelve of the study patients showed a marked increase in the release of calcium following the injection, revealing that they were prone to malignant hyperthermia. The injection caused no systemic side effects and carbon dioxide pressure returned to normal within an hour in all participants.