A model for comparison of local anesthetics in man.

Ten patients scheduled for bilateral arm surgery were given general anesthesia plus, on one side, an axillary brachial plexus block. Ten additional patients scheduled for bilateral foot surgery were similarly given general anesthesia plus an ankle block on one side. A within-patient blind comparison of postoperative analgesia between blocked and unblocked side was performed. An additional 10 patients scheduled for bilateral foot surgery had one side blocked with lidocaine and the other side blocked with bupivacaine for comparison of postoperative analgesia. Postoperative analgesia recorded by a nurse observed was significantly better on the blocked side compared with the unblocked side. This difference was greater for ankle blocks. There were no differences between the analgesic measures for lidocaine and bupivacaine ankle blocks over the 6-hour study period.