Dexamethasone or Clonidine: Which is the Better Additive to Local Anaesthetic in Supraclavicular Blocks

Background: Different drugs have been used as adjuvants with local anaesthetics in brachial plexus blocks. Adjuvants with better quality and faster onset and minimal side effects are looked for. Numerous studies have demonstrated the improvement in quality of anaesthesia when using dexamethasone and clonidine as additives but no study has been done for comparing both these drugs thus far. Aim: To compare the anaesthetic efficacy of adding Dexamethasone or Clonidine as adjuvants to local anaesthetic in supraclavicular brachial plexus block. Method: This trial was conducted in Calicut Medical College on a group of fifty patients requiring elbow, forearm or hand surgeries. They were randomized into two groups of 25 each. The block was performed using nerve stimulator guidance. Group 1 received local anaesthetic solution (20 ml 2 % Lignocaine with 1: 200000 adrenaline plus 10 ml 0.25 % Bupivacaine) plus 8mg dexamethasone. Group 2 received the same local anaesthetic solution plus 0.150 mg Clonidine. The observed parameters were onset of sensory and motor blockade, the duration of analgesia and presence of any side effects. Results: Mean onset of sensory block was 6.36+2.09 and 8.16+2.34, minutes in Group 1and Group 2 respectively. Mean onset of motor block was 8.16+2.17 and 9.96+2.45 minutes in Groups 1 and Group 2 respectively. Mean duration of analgesia in Groups 1 and Group 2 were 835.2+287.0 and 698.2+214.4 minutes respectively. No major side effects were noted in both the groups. Conclusion: Dexamethasone is a better additive to local anaesthetic than Clonidine in supraclavicular block because it causes earlier onset of sensory block and longer duration of action.