Todetermine the effects of addition of magnesium sulphate to Bupivacaine-fentanyl spinal anaesthesia with respect to sensory and motor blockade

Abstract

Background: One of the recent additions to the list of adjuvants that are used intrathecally, is Magnesium. It may improve the quality and duration of spinal anaesthesia. It acts by blocking the N-methyl-D-asparate (NMDA) channels in a voltage dependent way, reducing NMDA – induced currents. While the systemic use of Magnesium sulphate (MgSO4) reduces the postoperative opioid requirements, its intrathecal use is not evaluated extensively. Objectives: To determine the effect of addition of magnesium sulphate to Bupivacaine – fentanyl spinal anaesthesia with respect to onset of sensory and motor blockade, duration of analgesia and adverse effects if any. Methods: A prospective non-randomized controlled study was designed to compare the effects of addition of 50 mg of Magnesium sulphate (MgSO4) to Bupivacaine – fentanyl spinal anaesthesia. All adult patients undergoing lower abdominal and lower limb surgeries under Spinal Anaesthesia in the department of anaesthesiology at Vijayanagar Institute of Medical Sciences (VIMS), Bellary were included in the study. Results: The mean onset of sensory and motor blockade, peak sensory time were comparable between the two groups (p>0.05) however there was statistically significant difference between the groups with respect to duration of analgesia (128±8.6 min in fentanyl group and 136±13.1 min in fentanyl magnesium group, p=0.001) and the sedation score (p=0.001). Conclusions: Addition of magnesium sulfate (50 mg) to intrathecal fentanyl (25 ?g) for elective lower abdominal and limb surgeries has prolonged the duration of fentanyl analgesia without any significant side effects. Keywords: Bupivacaine, Fentanyl, Spinal anaesthesia, Sensory and motor blockad