A comparative study between the addition of MgSO4against dexamethasone to bupivacaine in the prolongation of ultrasound-guided interscalene nerve block for shoulder arthroscopy

Abstract

Background Local anesthetic adjuvants have been studied previously to prolong the duration of analgesia after peripheral nerve block and thus reduce postoperative adverse reactions associated with excessive systemic analgesic intake. The aim of this study was to compare the addition of MgSO 4 against dexamethasone to bupivacaine in the prolongation of ultrasound-guided interscalene brachial plexus block (ISPB) for shoulder arthroscopy. Patients and methods A total of 63 patients, ASA I and II grades, undergoing arthroscopic rotator cuff repair were enrolled in this study. The ISPB was performed with 0.5% bupivacaine 20 ml plus either 5 ml of 10% MgSO 4 (group M) or 5 ml of normal saline containing dexamethasone 8 mg (group D) or 5 ml of 0.9% NaCl (group C). The following data were collected: the onset of sensory block, the analgesic duration (time of the first call for analgesics), the occurrence of satisfactory motor block, the motor block duration, and postoperative analgesic consumption. Results The magnesium sulfate group and the dexamethasone group patients showed significantly higher analgesic duration values and significantly lower total meperidine consumption values than control group patients. Conclusion The addition of either magnesium sulfate or dexamethasone to bupivacaine in ISPB prolongs the analgesic duration significantly and also decreases the postoperative analgesic consumption.