Intra-articular versus intravenous magnesium-sulfate as adjuvant to femoral nerve block in arthroscopic knee surgery under general anesthesia: Randomized controlled trial

Abstract

AbstractBackgroundThe combined use of intra-articular (IA) or intravenous (IV) magnesium-sulfate (mgso4) with femoral nerve block might be associated with additive effects on the duration and quality of postoperative analgesia in arthroscopic knee surgery.Patients and methodsThis randomized controlled double-blind study included 90 patients. Femoral nerve block was performed in all patients using 20ml 0.25% bupivacaine before induction of general anesthesia. At the end of surgery patients were randomly allocated into: Group-IA (intra-articular 1g MgSO4 in 20ml), Group-IV (intravenous 1g MgSO4 in 20ml), and Group-P (20ml intra-articular and 20ml intravenous normal saline). 20ml normal saline was given IV in IA group and IA in IV group. Visual analogue pain score (VAS) at rest, with movement, time to first postoperative rescue analgesia, total postoperative diclofenac consumption, and the number of meperidine rescue doses during the first 24h postoperatively were measured.ResultsPain scores were comparable in the three groups at 2 and 4h and were significantly higher in the control group at 6h and over 24h. Group IA had the lowest pain scores. Duration of analgesia was significantly higher [11.6 (4.5) h] in IA group compared to [7.5 (3.6) h] in IV group and [5.2 (2.3) h] in control group (p<0.01). Total Diclofenac over 24h was significantly lower in IA group [73.8 (50.9) mg] versus [138.4 (51.6) mg] in IV group and [186.0 (43.9) mg] in the control group (p<0.01).ConclusionThe combined use of femoral nerve block with IA or IV MgSO4 is associated with significant reduction of the intensity and duration of postoperative pain and postoperative analgesic requirements in patients undergoing arthroscopic knee surgery with the IA MgSO4 being superior to IV route of administration