Body Temperature Changes during Surgery not involving Body Cavities:Epidural versus General Anesthesia

Forty adult patients of two groups scheduled for vascular and orthopedic surgery of the lower extremities were enrolled in a study comparing bodytemperature changes under either epidural (EA, 20 patients) or general (GA, 20 patients) anes thesia. Temperature recordings were obtained fromtympanic membrane (TM) and axilla, and were collected preoperatively, immediately after induction in anesthesia and then at twenty-min intervalsfor the first three hours of surgery. Body temperatures at the two measurement sites were decr eased gradually throughout the studied period in a similarpattern in both groups of patients. At the end of the third hour after induction in anesthesia, tympanic and axillary temperatures in the EA group weredecreased by –1.06 °C ± 0.12 (P < 0.01) and –1.01 °C ± 0.14 (P < 0.01) respectively. In the GA group the corresponding decreases were –1.04 °C ±0.31 (P < 0.01) and –0.94 °C ± 0.25 (P < 0.01). Comparing the corresponding measurement sites of the two groups, neither tympanic nor axillarytemperatures were differed significantly at any time period. Within each of the groups, axillary measurements were significantly lower than the tympanicmeasurements at all intervals (mean differences between the two measurement sites were 0.32 °C ± 0.07 and 0.28 °C ± 0.04 in the EA and GA groupsrespectively), and had an average correlation coefficients of 0.91 ± 0.02 and 0.77 ± 0.12 respectively. We concluded that, patients undergoing prolongedperipheral surgical procedures are at the same risk of developing intraoperative hypothermia under epidural or general anesthesia, therefore,perioperative body temperature should be monitored properly regardless to the type of anesthesia.

Key words:
monitoring – tympanic temperature – axillary temperature – regional anesthes ia