Background: To compare intra- and postoperative clinical properties of interscalene brachial plexus block performed with either 0.5% ropivacaine or 0.5% bupivacaine.
Experimental design: prospective, randomized, double-blind study.
Setting: in patient at the University Hospital, Department of Orthopedic Surgery.
Patients: 30 ASA physical status I-II patients scheduled for elective shoulder surgery.
Interventions: interscalene brachial plexus block was performed using the multiple injection technique and a nerve stimulator by injecting 20 ml of either 0.5% ropivacaine (n = 15) or 0.5% bupivacaine (n = 15). Postoperative analgesia consisted of 100 mg intravenous ketoprofen, if required. A blind observer evaluated hemodynamic variables as well as sensory and motor blocks from the end of injection to achieve a surgical anesthesia (readiness for surgery: loss of pinprick sensation from C4 to C7 with the inability to elevate the operated limb against gravity). The time lasting from block placement to first requirement for postoperative pain medication was also recorded.
Results: No differences in anthropometric parameters and hemodynamic variables were observed throughout the study, and no signs of central nervous system (CNS) and cardiovascular toxicity, or other untoward events were reported in any patients. Readiness for surgery was obtained after 28 +/- 15 min with 0.5% bupivacaine and 22 +/- 8 min after 0.5% ropivacaine (p = NS). No differences in postoperative pain relief was observed between the two groups (11.1 +/- 5 hrs after 0.5% ropivacaine and 10.9 +/- 3.9 hrs after 0.5% bupivacaine, respectively).
Conclusions: This study confirmed that 0.5% ropivacaine has clinical properties similar to those of 0.5% bupivacaine, when used for interscalene brachial plexus block, providing similarly long duration in postoperative pain relief. Compared with bupivacaine, ropivacaine has the further advantage of a lower potential for central nervous system and cardiovascular toxicity.