Inadvertent hypothermia prevention: the anaesthetic nurses' role.

Up to 90% of patients experience hypothermia perioperatively. Inadvertent hypothermia can have a profound physiological effect on the body, varying from mild vasoconstriction and feeling cold to cardiac arrest and death. Anaesthesia, general or regional, increases the risk as the normal protective reflexes such as shivering are absent, particularly when muscle relaxants are used. The very young and the elderly are particularly vulnerable. Preoperative assessment is essential. The greatest reduction in temperature occurs in the first hour of surgery, as a result of patient exposure, skin disinfection with cold fluids, inhalation of cold volatile gases and the administration of cold intravenous fluids, as well as exposure to cool theatre temperatures. If the theatre temperature drops below 21 degrees C, all patients will develop hypothermia. Patients lose heat through radiation, convention and conduction, with conduction having the greatest effect. Forced air warmers such as the Bair Hugger are the most effective means of preventing and treating heat loss. They should be used routinely although their contribution to infection also needs to be considered. Nurses should be aware of the risks of hypothermia so that modes of prevention can be employed to minimize the risks of inadvertent hypothermia.