Background and Objectives: Continuous spinal anesthesia via a spinal catheter allows adjusting the duration and extent of anesthesia to surgical needs, maintenance of hemodynamic stability, and good postoperative analgesia. This study was designed to determine the median effective local anesthetic dose of plain ropivacaine and bupivacaine administered intrathecally for interstitial brachytherapy of the lower abdomen using the Dixon up-and-down method.
Methods: Forty patients were randomly allocated to receive either intrathecal bupivacaine 5 mg per mL or ropivacaine 10 mg per mL via a 24-gauge spinal catheter at the L3-4 interspace. The initial dose was 10 mg of bupivacaine or 20 mg of ropivacaine; the dosing intervals were 1 mg and 2 mg, respectively. Doses for subsequent patients were determined by the response of the previous patient in that group. Successful anesthesia was defined as a loss of sensation to a cold stimulus at the T6 level and full motor blockade within 20 minutes after administration of the local anesthetic.
Results: The median effective local anesthetic dose for intrathecal bupivacaine was 11.2 mg (95% confidence interval [CI], 10.3-12.1) and 22.6 mg for ropivacaine (95% CI, 20.5-24.6). A relative analgesic potency ratio of 0.50 (95% CI, 0.44-0.56) was calculated between the median effective local anesthetic dose of intrathecal bupivacaine and ropivacaine.
Conclusions: Bupivacaine and ropivacaine are appropriate for continuous spinal anesthesia for interstitial radiation therapy procedures of the lower abdomen. In the dose-ranges investigated, intrathecal ropivacaine is approximately half as potent as bupivacaine.
- Spinal anesthesia
- Spinal catheter
- Median effective local anesthetic dose
Statistics from Altmetric.com
Reprint requests: Andrea Michalek-Sauberer, M.D., Department of Special Anesthesia and Pain Control, Medical University of Vienna, Vienna General Hospital, Waehringer Guertel 18-20, A-1090 Vienna, Austria. E-mail:
See Editorial page 1
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.