This research study is being done in order to find out if there is any difference in the
effectiveness of ultrasound guided supraclavicular brachial plexus nerve block that can be
achieved with 3 different amounts of ropivacaine 0.5% (20 ml, 30 ml, and 40 ml). The
investigators want to show if you can have a successful nerve block with less amount of local
anesthetic, thus potentially decreasing the risk of side effects.