Lidocaine vs. magnesium: effect on analgesia after a laparoscopic cholecystectomy

Background: This double‐blinded study aimed at evaluating and comparing the effects of magnesium and lidocaine on pain, analgesic requirements, bowel function, and quality of sleep in patients undergoing a laparoscopic cholecystectomy (LC). Methods: Patients were randomized into three groups (n=40 each). Group M received magnesium sulfate 50 mg/kg intravenously (i.v.), followed by 25 mg/kg/h i.v., group L received lidocaine 2 mg/kg i.v., followed by 2 mg/kg/h i.v., and group P received saline i.v. Bolus doses were given over 15 min before induction of anesthesia, followed by an i.v. infusion through the end of surgery. Intraoperative fentanyl consumption and averaged end‐tidal sevoflurane concentration were recorded. Abdominal and shoulder pain were evaluated up to 24 h using a visual analog scale (VAS). Morphine consumption was recorded at 2 and 24 h, together with quality of sleep and time of first flatus. Results: Lidocaine or magnesium reduced anesthetic requirements (P<0.01), pain scores (P<0.05), and morphine consumption (P<0.001) relative to the control group. Lidocaine resulted in lower morphine consumption at 2 h [4.9 ± 2.3 vs. 6.8 ± 2.8 (P<0.05)] and lower abdominal VAS scores compared with magnesium (1.8 ± 0.8 vs. 3.2 ± 0.9, 2.2 ± 1 vs. 3.6 ± 1.6, and 2.1 ± 1.4 vs. 3.3 ± 1.9) at 2, 6, and 12 h, respectively (P<0.05). Lidocaine was associated with earlier return of bowel function and magnesium was associated with better sleep quality (P<0.05). Conclusion: I.v. lidocaine and magnesium improved post‐operative analgesia and reduced intraoperative and post‐operative opioid requirements in patients undergoing LC. The improvement of quality of recovery might facilitate rapid hospital discharge.