Effects of clonidine-bupivacaine combination on the onset and duration of brachial plexus block in upper extremities surgeries: a preliminary report

Abstract

Objective Delayed onset of action and incomplete anaesthesia are often observed after brachial plexus block. Efforts have been made to hasten the onset of sensory and motor blocks as well as prolonging the duration of anaesthesia by combining several adjuvants to local anaesthetic agents for brachial plexus block. This study determined the onset of sensory and motor blocks and the duration of analgesia when clonidine was added to bupivacaine in patients who had upper extremities surgery under brachial plexus block. Methods This prospective comparative single blind study involved randomization of 40 ASA I-II patients scheduled for upper extremities surgery under periclavicular brachial plexus blocks into two equal groups. Group CB received 1 mL of clonidine (100 µg) and 29 mL of 0.5% bupivacaine while group B received 1 mL of water for injection and 29 mL of 0.5% plain bupivacaine. The onset of sensory block, motor block, duration of analgesia, and first request to rescue analgesia were assessed in the two groups. Results The onset of sensory and motor blocks was significantly faster in group CB compared with group B, 8.55 ± 3.0 versus 14.75 ± 5.7 min (P = 0.000) and 5.05 ± 1.1 versus 11.5 ± 4.6 (0.000), respectively. Similarly, the duration of sensory and motor blocks were 461 ± 94.2 versus 364 ± 39.1 min (P = 0.000) and 540 ± 81.3 versus 441.5 ± 41.5 min (P = 0.000), respectively. The time to request for rescue analgesia was longer in group CB in comparison with group B, 9.7 ± 2.3 versus 8.8 ± 2.5 hr but the difference was not statistically significant, P = 0.244. Conclusion Brachial plexus block with bupivacaine/clonidine reduced the onset time of sensory and motor blocks and prolonged the duration of analgesia and time to request for rescue analgesia.