Clonidine as an adjuvant to local anaesthetic axillary brachial plexus block: a randomized, controlled study

Background. We compared the effects of clonidine added to levobupivacaine and bupivacaine on axillary brachial plexus block as well as the effectiveness of levobupivacaine alone compared with bupivacaine alone. Methods. In this prospective, randomized, controlled, double-blind trial, four groups of 20 patients each were investigated, using (i) 40 ml of levobupivacaine 0.5% plus 0.150 mg of clonidine, (ii) 40 ml of levobupivacaine 0.5% plus 1 ml of NaCl 0.9%, (iii) 40 ml of bupivacaine 0.5% plus 0.150 mg of clonidine, and (iv) 40 ml of bupivacaine 0.5% plus 1 ml of NaCl 0.9%, respectively. The onset of motor and sensory block and duration of sensory block were recorded. Results. There was no significant difference in duration between groups, but a significantly higher variance (P < 0.001) was found in the two groups with clonidine than in the two groups without. Conclusions. These findings suggest responder and non-responder behaviour is a result of the addition of clonidine.