THE EFFECT OF MAGNESIUM SULFATE ON PERIOPERATIVE PAIN AND SERUM NOREPINEPHRINE LEVEL IN DIAGNOSTIC ARTHEROSCOPIC SURGERY

In a randomized double blind clinical trial study with two parallel group, we assessed the analgesic effect of perioperative magnesium sulfate administration and its effect on serum norepinephrine 24h after diagnostic artheroscopic surgery in 50 ASA physical status I & II patients under general anesthesia with total intravenous anesthesia (TIVA) technique. The patients received either magnesium sulfate 50 mg/kg preoperatively and 8 mg/kg/h intraoperatively or the same volume of isotonic solution intravenously. Anesthesia was performed with midazolam (0.2mg/kg for induction, 1μg/kg /min for maintenance) and fentanyl (3 μg/kg) for induction, and atracurium (0.5 mg/kg) for intubation. Intraoperative pain was defined as an increase of systolic blood preasure and heart rate of more than 20% from baseline values (systolic blood preasure and heart rate 5 min after intubation) and was treated with bolus fentanyl (1-2μg/kg). Postoperative analgesia was achieved with fentanyl (0.5 μg/kg) and evaluated using the pain visual analog scale for 4h (0, 30, 60, 90, 120, 240min). Also 24h after surgery a blood sample was taken from the patients in order to measure serum norepinephrine. During intra-and postoperative period, patients in case group required significantly less fentanyl than those in control group (control group 75+40.18μg versus case group 41+32.97μg, p=0.002 and control group 153+65.87 μg versus case group 72+52.69 μg p=0.001 for intra and postoperative period, respectively) but there is no significant difference in serum level of norepinephrine between two groups. (case group 0.318+0.109 versus control group 0.312+0.182, p=0.9). We concluded that magnesium sulfate, although, reduce the intraoperative and postoperative pain and fentanyl requirement, but there is no significance difference in serum norepinephrine level 24h after surgery between two groups. So reduction of pain dose not have any effect on serum norepinephrine concentration.