FORCED-AIR SURFACE WARMING VERSUS ESOPHAGEAL HEAT-EXCHANGER IN THE PREVENTION OF PEROPERATIVE HYPOTHERMIA

Background: In a prospective, randomized, placebo-controlled study we investigated the efficacy of 2 different heating methods in 24 patient s undergoing abdominal surgery of at least 2 h expected duration. Meth ods: Group I: control, no active warming. Group II: forced-air surface warming on upper extremities and upper thorax. Group III: warming wit h oesophageal heat exchanger. All patients had a standardized, combine d general and epidural anaesthesia. Core and skin temperatures were me asured at induction of general anaesthesia, and subsequently every 30 min, and changes in total body temperature were calculated. Results: T here were no statistically significant differences between the 3 group s regarding demographic data. Patients in groups I and III developed h ypothermia, while this was not the case with patients in group II. Whe n using analysis of variance with repeated measurements, there was no significant difference in core temperature, comparing group I and grou p III (P=0.299) or the interaction between time and treatment of these groups (P=0.373). As a consequence, data from groups I and III were p ooled and regarded as an internal group on the one hand, and group II as an external group on the other hand. Core temperature, the mean ski n temperature and total body temperature were significantly different comparing the internal group and the external group. The interaction b etween time and treatment was likewise found to be significantly diffe rent. Conclusion: We conclude that in major abdominal procedures lasti ng 2 h or more, serious hypothermia develops unless effective measures to prevent hypothermia are used. Forced-air warming of the upper part of the body is effective in maintaining normothermia in these patient s, while central heating with an oesophageal heat exchanger, at least in its present form, does not suffice to prevent hypothermia.