Ultrasound-guided Supraclavicular Brachial Plexus Block in Elderly

The study method is a step-up/step-down sequence model where the dose of local anesthetic for the following patient is determined by the outcome of the preceding block. The starting dose of 50:50 mixture of 0.5% levobupivacaine and 2% lidocaine is 30 mL. In the case of block failure, the dose will be increased by 5 mL. Conversely, block success will result in a reduction in dose by 5 mL. A blinded assistant will assess sensory and motor blockade in each nerve territory ( the median, radial, ulnar and musculocutaneous) at 5-min intervals up to 30 min after completion of US-SCB. Effective US-SCB will be defined as complete sensory blockade in the distribution of the radial, ulnar, median and musculocutaneous nerve.