The effect of adding magnesium sulfate to lidocaine in an interscalene plexus block for shoulder arthroscopic acromioplasty

Abstract

Background Incorporation of adjuvants into local anesthetics could potentially aid in producing satisfactory prolonged postoperative analgesic duration and reducing postoperative adverse reactions associated with excessive systemic analgesic intake. The aim of this trial was to study the effect of incorporating magnesium sulfate as an adjuvant into lidocaine in an interscalene plexus block (ISPB) for arthroscopic acromioplasty. Materials and methods Sixty ASA I and II grade patients scheduled for elective arthroscopic acromioplasty under ultrasound guidance and peripheral nerve stimulation technique were allocated randomly to two groups: group L, which included patients who received 20 ml of lidocaine 2% with epinephrine 1 : 200 000 plus 5 ml 0.9% NaCl, and group LM, which included patients who received 20 ml of lidocaine 2% with epinephrine 1 : 200 000 plus 5 ml of 10% MgSO 4 (500 mg MgSO 4 ). The following data were collected: the onset of sensory block, the occurrence of satisfactory motor block, sensory block duration, Numeric Rating Scale (NRS) at the first analgesic dose, motor block duration, total morphine consumption in the first 24 h, and the presence of any adverse reactions. Results Patients in the magnesium sulfate group showed a prolonged postoperative analgesic duration, the NRS records decreased significantly on the first analgesic dose, and morphine consumption was reduced, and no adverse events related to its use in ISPB were recorded. Conclusion The addition of magnesium sulfate to lidocaine in ISPB significantly prolongs the analgesic duration and reduces the NRS score and postoperative opioid requirements in shoulder arthroscopic acromioplasty without side effects.