A comparative study of sequential epidural bolus technique and continuous epidural infusion

Background: In this randomized, double-blind study, the authors compared the effectiveness of a sequential epidural bolus (SEB) technique versus a standard continuous epidural infusion (CEI) technique of local anesthetic delivery. Both techniques used the same hourly dose of local anesthetic. Methods: Sixteen gynecologic patients undergoing abdominal surgery received postoperative epidural analgesia using 0.75% ropivacaine at a dose of 22.5 mg (3 nil) per hour. Patients were randomly assigned to one of two groups. in the SEB group (n = 8), patients received one third of the hourly dose every 20 min as a bolus. In the CEI group (n = 8), the hourly dose was administered as a continuous infusion. Analgesia was assessed by rest pain scored by a visual analog scale and pinprick to determine the number of separately blocked spinal segments on each side of the body. Doses of rescue medication for pain were also recorded. Results: The median number of blocked spinal segments was 19.5 (range, 18-24) in the SEB group and 11.5 (range, 10-18) in the CEI group (P < 0.001). The median difference in the number of blocked segments between the right and left sides was 0 (range, 0-1) in the SEB group and 2 (range, 0-6) in the CEI group (P < 0.04). No patients in the SEB group but one patient in the CEI group required rescue medication for pain. The visual analog scale pain score was 0 in both groups except for one patient in the CEI group during the study period. Conclusion: The SEB technique with ropivacaine provides superior epidural block compared with an identical hourly dose administered as a continuous infusion.