Intraoperative magnesium infusion as an adjuvant to bilateral single-injection thoracic paravertebral block for laparoscopic cholecystectomy

Background: Magnesium has antinociceptive effects. This study was designed to examine whether intraoperative administration of i.v magnesium with bilateral thoracic paravertebral block (PVB) enhances postoperative analgesia while reducing opioid consumption and opioid-related side effects. Methods: In this prospective randomized, double-blinded, controlled study, 59 patients undergoing laparoscopic cholecystectomy were given bilateral single injection PVB at the level of T5. Before induction of general anaesthesia, patients were assigned to two groups. Group M (magnesium group) received a loading dose of magnesium sulphate 30 mg per kg in 100 ml of normal saline over 10 min followed by an infusion of 10 mg per kgper h till the end of surgery. Control group (group C) received the same volume of normal saline as a loading dose followed by a continuous infusion. In both groups, postoperative pain was initially controlled by i.v. fentanyl titration and then fentanyl PCA. Cumulative PCA fentanyl consumption, pain intensities, sedation scores, cardiovascular and respiratory variables and opioid-related adverse effects were recorded for 36 h after operation.