Selective Trunk Block Versus Hybrid Interscalene-Supraclavicular Brachial Plexus Block for Anaesthesia of the Entire Upper Extremity: A Randomized Double-Blind Controlled Trial

Brachial plexus block (BPB) is frequently used as the sole anesthestic technique for upper extremity surgery. The choice of injection can be made from different approaches that often depends on the site of surgery because the extent of sensory-motor blockade after a BPB varies with the approach used. However, there is no single BPB technique that can consistently produce anesthesia of the whole ipsilateral upper extremity. Nevertheless, cases such as combined fracture of the upper humerus and forearm bones have to anesthetize the whole upper extremity for surgery or those with multiple comorbidities and unfit for general anesthesia. In these cases, multiple injections have to be made. Thus, a combined ultrasound guided (USG) interscalene-supraclavicular (IS-SC) BPB has to be used as the sole anesthetic for proximal humerus surgery but with a relatively large volume (35-50mL) of numbing medication, which often exceed the recommended maximum safety dose. Recently principal investigator has demonstrated that it is feasible to accurately identify majority of the main components of the brachial plexus above the clavicle, including the three trunks, using ultrasound imaging. As majority of the innervation of the upper extremity, i.e. shoulder, arm, elbow, forearm, wrist and hand, originates from the three trunks of the brachial plexus, principal investigator has proposed that selectively blocking the superior, middle and inferior trunks of the brachial plexus under ultrasound guidance, will produce anesthesia of the entire upper limb. Principal investigator refers this technique as selective trunk block (SeTB). The preliminary experience with SeTB for anesthesia of the entire upper limb with smaller volumes (25ml) of numbing medication is feasible and able to ensure total immobility of the whole upper limb that meets the essential requirement for surgery. In this study principal investigator hypothesizes that USG guided SeTB is not inferior to USG IS-SC BPB in terms of its ability to produce sensory-motor blockade.

The aim of this study is to compare the proportion of patients who develop "readiness for surgery" for 30 minutes between a SeTB and hybrid IS-SC BPB. In other words, comparing the clinical effectiveness in producing anesthesia of the whole ipsilateral upper limb between SeTB and hybrid IS-SC brachial plexus block.