[Normothermia and hypothermia from an anaesthesiological viewpoint]

For a long time the significance of perioperative accidental hypothermia was overlooked. The possible undesirable effects of a relatively small reduction in the body core temperature of 1.5-2.0 degrees C were generally unknown and the treatment options were limited. The unfavourable climatic conditions in the operation room favour heat loss and simultaneously, there is considerable disturbance of temperature regulation through general as well as spinal anaesthesia. In many studies it has now been shown that the resulting decrease in body temperature can have a negative effect on immune function, coagulation, the cardiovascular system and recovery behaviour. Heat loss in the perioperative phase should, therefore, be minimised by effective insulation. Nevertheless, a negative heat balance can often only be avoided by an additional heat treatment of the body surface which ideally should be initiated in the preoperative phase. If large volumes must be infused, an important additional measure is to prewarm these solutions. This is the only way in which the objective, to avoid a fall in body temperature to below 36 degrees C in the perioperative phase and the possible subsequent negative effects on the course of events, can be reached. The incidence of perioperative hypothermia is often underestimated so that in this phase a reduction in body core temperature of more than 2 degrees C will occur in more than 50% of patients if no special measures are undertaken. In addition, the undesirable effects of such a reduction in core temperature were barely known and even only a few years ago there were hardly any possibilities for reliable prevention or effective treatment. Therefore, in this article the causes of perioperative hypothermia will initially be described. In the second section the possible negative consequences of a reduction in body core temperature will be presented and in the last section the resulting consequences for the practice will be discussed.