Comparison of single vs triple aliquot injection for supraclavicular brachial plexus block in upper limb orthopaedic trauma surgeries : A Randomised controlled trial

Supraclavicular block anesthetizes the brachial plexus where it is in its most compact form, thus providing a complete and reliable block for upper extremity surgery.1 Although the single injection (SI) ultrasound-guided corner pocket technique has been reported to have the highest success rate, this technique may miss the upper part of the plexus, resulting in an incomplete block. Cadaver and patient studies by using dye injections have demonstrated that injection into a single location does not result in the spread of the injected dye into all the compartments. Septae or a tight muscular membrane between the scalene muscles were found to separate roots of the plexus. Several studies comparing different approaches for brachial plexus block have demonstrated multiple injection techniques to be more successful, resulting in a faster onset of anesthesia and higher success rates with no increased incidence in complications. However, these trials did not show consistent results regarding the onset of block or the nerves blocked. The aim of this study was to compare the sensory block success rate of SI versus triple injection (TI). We hypothesized that a TI performed at the upper, middle, and lower parts of the plexus would have a higher success rate compared with the SI technique. In single injection using in plane approach a 22g 5 cm needle will be advanced until the tip is at the junction of first rib and subclavian artery.15 ml of 0.75% ropivacaine with 1 mcg/kg clonidine will be injected with negative aspiration. Similarly for  triple injection 5 ml each of the drug will be injected in corner , middle and above pocket. The time of onset of block will be measured as the primary outcome. We hypothesized that triple injection is more efficacious than single injection.