Postoperative analgesia using continuous lumbar epidural infusion of ropivacaine in comparison with bupivacaine

BACKGROUND: Epidural bupivacaine infusion is a commonly used technique for postoperative analgesia because of its motor-sparing properties. Recently a new long acting local anesthetic, ropivacaine, has become available. The aim of this study was to investigate the efficacy of ropivacaine and bupivacaine with regard to postoperative analgesia when administered continuously into the lumbar epidural space. METHODS: All patients were ASA I II and undergoing ipsi-lateral leg orthopedic surgery with epidural or combined spinal-epidural anesthesia. Patients were randomly assigned to following three groups: 0.1% ropivacaine (0.1 R); 0.2% ropivacaine (0.2 R); 0.125% bupivacaine (0.125 B). At the end of surgery, continuous infusion was begun at a rate of 6 ml.hr 1 after a bolus epidural administration of 5 ml of 0.2% ropivacaine in R groups and 0.25% bupivacaine in B group. Sensory and motor block, blood pressure, pulse rate, verbal pain score (VPS), analgesic consumption were assessed at 20 min, 1, 3, 10-20 hrs following the beginning of continuous infusion. RESULTS: Vital signs were stable at every measuring point in all groups. In 0.1 R group (n = 20), the spread of sensory block at 3 hrs after infusion was lower than 0.2 R group (n = 19), and VPS during the study was higher than 0.125 B group (n = 17). Bromage scale after 3 hrs was higher in 0.2 R group compared with 0.125 B group. The degree of sensory and motor block gradually decreased, resulting in little difference between the groups. When epidural anesthesia was spread over the surgical area throughout the study, 0.2 R or 0.125 B was sufficiently relieved from postoperative pain. CONCLUSIONS: After leg orthopedic surgery, 6 ml.hr-1 of 0.2 R or 0.125 B provided enough postoperative analgesia when the spread of anesthesia covered the operated area. 0.2 R would be better compared to 0.125 B in continuous epidural infusion for postoperative analgesia due to less systemic toxicity, even though it accompanies a little more intense motor block.