Interscalene Versus Supraclavicular Approach to Brachial Plexus Nerve Blockade and Local Anesthetic Volume Effect on the Incidence of Phrenic Nerve Dysfunction during Shoulder Surgery

Interscalene blockade results in a significantly higher incidence of phrenic nerve dysfunction when compared to effects from a supraclavicular approach nerve block. In addition, using local anesthetic volumes more than 20 ml resulted in a higher incidence of phrenic nerve dysfunction, regardless of approach to the brachial plexus when compared to using volumes of 20 ml or less. There were no differences in brachial plexus blockade efficacy or duration of effect between the 2 approaches and using greater or less than20ml volumes of local anesthetic.