and Objectives: Epidural anesthesia decreases the core temperatures triggering vasoconstriction and shivering, presumably by increasing apparent (as opposed to actual) lower-body temperature. We therefore tested the hypothesis that epidural anesthesia also increases the overall perception of warmth. Methods: We studied 8 volunteers in a randomized, cross-over protocol separated by at least 48 hours. On one day, epidural anesthesia was induced to a T11 sensory level; the other day was a control

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... ithout anesthesia. Core temperature and upper-body skin temperatures (33°C) were kept constant throughout. Lower-body skin temperature was set in a random order to 31°C, 32°C, 33°C, 34°C, 35°C, and 36°C and maintained by circulating water and forced air. At each temperature, the volunteers rated their thermal sensation with a visual analog scale (0 ϭ cold, 100 ϭ hot). Core temperature was 36.8 Ϯ 0.1°C on the control day and 36.7 Ϯ 0.1°C on the epidural day. Results: Scores for thermal sensation on the epidural day were near 47 mm at each lower-body skin temperature. On the control day, visual analog scores at a lower-body skin temperature of 31°C were 16 Ϯ 10 mm and increased linearly to 61 Ϯ 6 mm at 36°C. Control thermal sensation scores thus equaled those during epidural anesthesia when lower-body skin temperature was near 34°C. Conclusions: Thermal sensation with and without epidural anesthesia was comparable at a lower-body temperature near 34°C, which is a normal leg skin temperature. This suggests that autonomic and behavioral thermoregulatory consequences of epidural anesthesia differ -or that the current explanation for reduced vasoconstriction and shivering thresholds during epidural anesthesia is incorrect. Reg Anesth Pain Med 2001;26: 527-531.