Humidification and loss of body heat during anaesthesia. II: Effects in surgical patients.

Changes in temperature and body heat were measured in 30 patients. Despite the warming of most fluids given intravenously, all the patients ventilated with dry anaesthetic gases became cooler, with an average heat loss of 12.4 kilocalories per hour. In a group to whom the gases were delivered saturated at body temperature, the average hourly loss was 1.5 kilocalories. This difference is in agreement with the effects calculated from respiratory heat exchange, and indicates that heated humidification can help to limit or prevent the development of hypothermia in anaesthetized adults.