Effects of surgical site and inspired gas warming devices on body temperature during lower abdominal and thoracic surgery.

To evaluate the effects of surgical site and inspired gas warming and humidifying devices on body temperature, we studied rectal, tympanic membrane, and esophageal temperature changes in 48 patients. The patients were divided into 4 groups (n = 12), according to surgical site, lower abdominal surgery and thoracic surgery, and according to the warming device used, heat and moisture exchanger (ThermoVent 600) and heated humidifier (Cascade 1). The heated humidifier was controlled to warm inspired gases to about 35 degrees C. All body temperatures fell significantly during surgery. There was no difference in the tympanic membrane and esophageal temperature declines between the two surgical sites, but the decline in rectal temperature was larger in the lower abdominal surgery than in the thoracic surgery. At the end of surgery, all temperatures returned to the value before surgery, and the rectal and tympanic membrane temperatures even exceeded them. There was no difference between the effects of the ThermoVent 600 and Cascade 1. These results suggest that rectal temperature is influenced by the ambient temperature during lower abdominal surgery and that warming and humidifying devices for inspired gases do not prevent, but can restore the decline in body temperature during lower abdominal and thoracic surgery. The heated humidifier showed no advantage over the heat and moisture exchanger in our study.