Effects of Different Concentrations of Isoflurane on Core and Peripheral Temperature during General Anesthesia

Background : Precise temperature monitoring is essential during general anesthesia. Isoflurane induces vasodilation, which is correlated with changes in body temperature. The purpose of this study is to estimate the relationship between core temperature and peripheral body temperature which is usually used during anesthesia to determine changes in isoflurane concentration. Methods : Temperature measurements were performed in 46 patients of ASA physical status 1 or 2 undergoing oral & maxillofacial surgeries. During general anesthesia using isoflurane, body temperatures were measured every hour at the distal esophagus, the skin above the axillary artery and the rectum. Results : There was a weak linear relation between the changes of △Teso-axilla and isoflurane concentration, whereas there was no significant relation between the changes of △Teso-rectal and the isoflurane concentration. Conclusions : Axillary temperature was influenced by changes in isoflurane concentration, whereas the rectal temperature represented the core esophageal temperature during general anesthesia irrespective of changes in isoflurane concentration. (Korean J Anesthesiol 1999; 37: 745∼749)