Comparative Study of Epidural Fentanyl and Fentanyl Plus Magnesium for Postoperative Analgesia

BACKGROUND AND OBJECTIVESMagnesium has antinociceptive effects in animal and human models of pain.It is found that the addition of magnesium to postoperative epidural infusion of fentanyl may decrease the need for fentanyl.We undertook a study to compare the duration of postoperative analgesia after epidural Fentanyl and epidural Fentanyl plus magnesium administered postoperatively, along with side effects. METHODS AND MATERIALS50 patients undergoing elective lower limb surgeries were randomized into one of the two groups with 25 patients in each group.Combined Spinal Epidural Anaesthesia was used for all patients.Spinal anaesthesia with 2.5 cc of 0.5% hyperbaric bupivacaine was given.When sensory blockade regressed to L1, patients were given either 50 µg of Fentanyl (Diluted to 6 cc with normal saline, Group F) or 50 µg of Fentanyl plus 50 mg Magnesium (Diluted to 6 cc with normal saline, Group FM).Study drugs are administered by epidural route.Parameters like blood pressure, pulse rate, respiratory rate and oxygen saturation were monitored, and other side effects were noted STATISTICAL ANALYSISData were analysed by using Student t test and Chi-square/ Fisher Exact tests. RESULTSThere was significant difference in duration of analgesia between Group F (107 min) and Group FM (143 min).Haemodynamic parameters were stable in both the groups with minimal side effects. CONCLUSIONCo-administration of magnesium along with fentanyl for postoperative epidural analgesia results in prolongation of fentanyl analgesia without significant side-effects.