A Randomized, Prospective, Double-Blind Trial Comparing 3% Chloroprocaine Followed by 0.5% Bupivacaine to 2% Lidocaine Followed by 0.5% Bupivacaine for Interscalene Brachial Plexus Block

The combination of 2-chloroprocaine and bupivacaine (C/B) for regional anesthesia has been described, but its use was largely abandoned due to equivocal results in efficacy. In this prospective, double-blind, randomized study, we compared the onset of an interscalene block using C/B versus a combination of lidocaine and bupivacaine (L/B). Thirty patients scheduled for shoulder arthroscopy under interscalene block were divided into two groups of 15 each. One group (C/B) received 3% 2-chloroprocaine combined with bicarbonate and epinephrine, immediately followed by 0.5% bupivacaine and epinephrine, whereas the other group (L/B) received 2% lidocaine instead of 3% 2-chloroprocaine. Motor and sensory block were assessed every 15 s. The primary end-point was the time of onset to complete motor block. Time-to-event (survival) statistical analysis tests were applied. One L/B patient had a failed block, and was excluded. The median time to motor block for C/B and L/B was 90 (15-575) and 180 (15-3720) s, respectively (P = 0.0325), and to sensory block for C/B and L/B was 90 (30-600) and 210 (30-3900) s, respectively (P = 0.0185). Survival analysis showed that in 5 min, 13 of 15 patients from the C/B group but only 7 of 14 from the L/B group had a successful motor block. In 10 min, 15 of 15 patients from the C/B group but only 10 of 14 from the L/B group had a successful motor block. It took as long as 60 min to assess block success/failure for blocks in the L/B group. This study demonstrates that a successful block was more rapid using C/B than L/B for interscalene blocks.