The effects of an epidural infusion of ropivacaine versus saline on sensory block after spinal anesthesia

Background and Objectives: Several investigators have described the effect of bolus injections on sensory block during combined spinal epidural anesthesia. This study investigates the effects of the immediate epidural infusion of 0.2% ropivacaine versus 0.9% saline on spinal anesthesia. Methods: Forty-four patients undergoing partial hip replacement were randomly assigned to 2 groups, receiving epidural infusion of 0.2% ropivacaine 10 mL/h (group R, n = 22) or 0.9% NaCl 10 mL/h (group S, n = 22), immediately after spinal anesthesia with 7.5 mg 0.5 % hyperbaric bupivacaine. Postoperative analgesia was provided in both groups using a ropivacaine patient-controlled epidural analgesia technique. Sensory block, motor block, postoperative pain scores, ropivacaine consumption, and patient satisfaction were recorded. Results: There was no difference between the 2 groups in the characteristics of the sensory block. The duration of motor block was prolonged in group R (312 +/- 95 minutes vs 198 +/- 78 minutes; P <.001). Postoperative pain scores and 24-hour ropivacaine consumption were similar among groups. Demand/delivery ratio was 1.6 in group R and 3.5 in group S (P =.048). A significantly higher number of patients in group R described their satisfaction as excellent (20 patients vs 6 patients; P <.001). Conclusions: Epidural infusion of ropivacaine 0.2% initiated immediately after spinal anesthesia prolonged the regression of motor block but not the regression of sensory block when compared with saline infusion.