Comparison of forced-air warming and resistive heating.

Abstract

BACKGROUND: Perioperative hypothermia is common during anesthesia and surgery and is accompanied by several complications. Forced-air warming is recognized as an effective procedure to prevent hypothermia. The aim of this study was to compare a resistive heating device with a forced-air warming device. METHODS: Prospective randomized trial. SETTING: heat transfer laboratory of a University hospital. PARTICIPANTS: six healthy volunteers. INTERVENTIONS: warming with a forced-air warming device (BairHugger 505 and Upper Body Blanket 522; Arizant Healthcare Inc., Eden Prairie, MN, USA) or a resistive heating device (Geratherm Adult system; Geratherm Medical AG, Geschwenda, Germany). MEASURES: heat transfer was measured with 11 calibrated heat flux transducers on the upper body. Additionally, blanket and skin temperatures were measured. The t-test for matched pairs was used for statistical evaluation. RESULTS: Skin temperature under the covered surface was not statistically different between the two groups (37.3+/-0.2 degrees C in the forced-air warming group and 37.8+/-0.2 degrees C in the resistive heating group). In contrast, blanket temperature (40.3+/-0.6 degrees C vs 38.1+/-0.4 degrees C, P=0.002) and heat transfer (13.2+/-3.6 W vs 7.8+/-1.9 W, P=0.048) were significantly higher in the resistive heating group. CONCLUSION: Heat transfer in the resistive heating system was significantly greater than that of the forced-air warming system.