Effects of Magnesium Sulphate on the Onset and Duration of Neuromuscular Blockade by Cisatracurium in Adult Patients Undergoing Transpedicular Screw Fixation Surgery Under General Anesthesia
Background: In the past, various drugs have been used to potentiate the effects of non-depolarizing neuromuscular blocking agents. Among these agents, Magnesium Sulphate has been found to be effective and safe. In our part of the world, Cisatracurium had not been used commonly until recently when its availability has made possible its use as a long-term non-depolarizing neuromuscular blocking agent. So, we decided to use MgSo4 with cisatracurium to see its effectiveness in patients undergoing transpedicular screw fixation surgery. Objective: To compare the onset, duration of action and mean intraoperative consumption of Cisatracurium in adult patients undergoing Transpedicular screw fixation (TPSF) surgery under general anesthesia with and without pretreatment as well as intraoperative use of Magnesium sulphate. Study Design: A Randomized Controlled study. Settings: Department of Orthopedics & spine Centre, Ghurki Trust Teaching Hospital (GTTH), Lahore Pakistan. Duration: Six months from 1st June 2019 to 30th November 2019. Methodology: In this study, 46 patients were randomly divided into two groups by lottery method (23 in each group). In both groups, patients either received magnesium sulphate (Mgso4) 50 mg/kg in 100 ml of 0.9% Normal saline or 100 ml of only 0.9% Normal saline intravenously 20 minutes before induction of general anesthesia with Propofol, Fentanyl and Cisatracurium. After induction of general anesthesia, group M received continuous infusion of Mgso4 (20 mg/kg/hr) until the beginning of skin closure. Maintenance dose of Cisatracurium was given when first twitch was noted by Train-of-Four. Time of onset, duration of neuromuscular blockade and total intra-operative consumption of Cisatracurium were noted. Heart rate, mean arterial blood pressure and serum ionized Magnesium levels were also measured. Results: Time of onset was significantly shorter in the group M than group N (P < 0.05). Duration of neuromuscular block was significantly prolonged in group M as compared to group N (P< 0.05) and the total consumption of Cisatracurium during surgery was significantly lesser in group M when compared with group N (P< 0.05). Serum ionized Magnesium levels were significantly more in group M comparatively (P<0.05). There were no significant difference in heart rate and mean arterial blood pressure changes in two groups (P>0.05). Conclusion: Magnesium impairs neuromuscular transmission at blood levels that did not affect hemodynamics and significantly augments the neuromuscular blockade by Cisatracurium.