Postoperative Analgesia of Magnesium Sulfate in Suprascapular Nerve Block Following Shoulder Arthroscopy

* Arthroscopic shoulder surgeries in adults are accompanied with severe immediate postoperative pain reported in approximately 45% of patients. For quicker recovery and rehabilitation of these patients, postoperative analgesia is mandatory. * Different analgesic modalities have been proposed including parenteral opioids, intra-articular injection of local anesthetics, interscalene brachial plexus block (ISB), and a suprascapular nerve block (SSNB), with varying degrees of effectiveness and multiple reported side effects. * A recent meta-analysis demonstrates that suprascapular block results in 24-h morphine consumption and pain scores similar to ISB, so, it may be considered an effective and safe alternative for interscalene block in shoulder surgery, with less motor restriction, and fewer complications. * Different agents are used as adjuvants to local anesthetics during peripheral nerve block to prolong its analgesic action including magnesium sulfate. * A meta-analysis by Mengzhu et al., concluded that magnesium sulfate combined with local anesthetics in perineural nerve blocks provided better analgesic efficacy and may be a promising analgesic for perineural nerve blocks. * Antinociceptive effects of magnesium are due to the regulation of calcium influx into the cell and a non-competitive antagonism of the NMDA receptors

The aim of this study is to evaluate the effects of magnesium sulfate as an adjuvant to bupivacaine in suprascapular nerve block on the duration and quality of postoperative analgesia following shoulder arthroscopy, postoperative pain VAS scores, intraoperative fentanyl requirements, sedation scores, respiratory depression, postoperative 24 hours cumulative morphine consumption.