Article Text

Download PDFPDF
Effects of Epidural Anesthesia on Thermal Sensation
  1. Angela Rajek, M.D.,
  2. Robert Greif, M.D. and
  3. Daniel I. Sessler, M.D.
  1. From the Department of Anesthesia and Perioperative Care, University of California (A.R., R.G.), San Francisco, California; Departments of Cardio-Thoracic and Vascular Anesthesia and Intensive Care Medicine, University of Vienna (A.R.), Vienna, Austria; Department of Anesthesiology and Intensive Care Medicine, Donauspital/SMZO (R.G.), Vienna, Austria; Outcomes ResearchTM Institute and Department of Anesthesiology, University of Louisville (D.I.S.), Louisville, Kentucky; and Ludwig Boltzmann Institute (D.I.S.), University of Vienna, Vienna, Austria.
  1. Reprint requests: Daniel I. Sessler, M.D., University of Louisville, Abell Administration Center, Room 217, 323 E Chestnut St, Louisville, KY 40202-3866. E-mail: sessler{at}


Background 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 without 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 = cold, 100 = hot). Core temperature was 36.8 ± 0.1°C on the control day and 36.7 ± 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 ± 10 mm and increased linearly to 61 ± 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.

  • Behavior
  • Neuraxial anesthesia
  • Regional anesthesia
  • Thermoregulation
  • Temperature

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.


  • Supported by National Institutes of Health Grant GM49670, the Joseph Drown Foundation (Los Angeles, CA), and the Commonwealth of Kentucky Research Challenge Trust Fund (Louisville, KY). Mallinckrodt Anesthesiology Products, Inc (St. Louis, MO) donated the thermocouples used; Augustine Medical, Inc (Eden Prairie, MN) donated the fluid warmer. The authors do not consult for, accept honoraria from, or own stock or stock options in any company related to this research.