A prospective randomised study of adjuvants for supraclavicular brachial plexus block: Clonidine vs Dexamethasone

 Supraclavicular brachial plexus block is among foremost technique of regional anaesthesia administered during upper-limb surgery. Different adjuvants have been used with varied results for prolonging the sensory and motor blockade. Dexamethasone and Clonidine have been established as suitable adjuvants for blocks. Adding adjuvants to local anaesthetic drugs in nerve blocks has many benefits. We studied performance of dexamethasone or clonidine as additives to local anaesthetic in subclavian perivascular block as a part of upper limb surgery. Aim was to ascertain which of them is a better adjuvant. Study population was randomized to 2 groups of 50 patients each. Group 1 was given 5 ml of 2% lignocaine and 15 ml 0.5% bupivacaine with 8mg dexamethasone. Group 2 received 5ml 2% lignocaine and 15 ml 0.5% bupivacaine with 0.150 mg clonidine. Time to establishment of sensory & motor block, duration of analgesia and any adverse effects were observed. Statistical analysis was done with SPSS 13.0. Quantitative variables were assessed using student t test. Qualitative variables were analysed using Chi square test. P value < 0.05 was defined as significant.  Onset of sensory blockade was at 7.23+4.24 in group 1 and 8.36+2.68 minutes in Group 2. Average time to motor block was at 8.48+3.22 minutes in Group 1 and 9.58+3.71 minutes in Group 2. Analgesia’s duration in Group 1 and Group 2 was 998.2+338.5 and 879.3+284.5 minutes respectively. No major adverse events were seen in either group.  Performance of dexamethasone was similar to clonidine as adjunct to local anaesthetic in subclavian perivascular approach of brachial plexus block. However, it has faster sensory and motor blockade’s onset. Analgesia’s duration observed was found to be longer, though the difference was statistically insignificant.