Efficacy of Magnesium Sulphate in Attenuation of Succinylcholine Induced FasciculationsA Randomised Clinical Study

Abstract

Introduction: Magnesium Sulphate (MgSO4 ) pre-administration is effective in reducing Succinylcholine (Sch) induced fasciculations due to its effect at presynaptic end plate. Magnesium competes with calcium at the pre-synaptic end plate of neuromuscular junction and inhibits the release of acetylcholine (Ach) from the motor nerve terminal and to a lesser extent, decreases the sensitivity of the postjunctional membrane and reduces the excitability of the muscle fibre. Aim: To evaluate three doses of MgSO4 in reducing the incidence and severity of fasciculations and correlate with the serum magnesium levels. Materials and Methods: This prospective, randomised clinical trial was at Vijayanagar Institute of Medical Sciences (VIMS), Ballari, India. Ninety consenting adult patients aged 20-50 years scheduled for elective surgeries with endotracheal intubation under general anaesthesia were randomly allocated to three groups- Group 1, Group 2 and Group 3, to receive Injection (Inj.) MgSO4 20 mg/kg, 30 mg/kg and 40 mg/kg, respectively, before induction. Induction with Inj. propofol (2 mg/kg) was followed by administration of Inj. Sch (1.5 mg/kg). The main outcome parameters were the incidence of fasciculations and grading of the severity. Haemodynamic responses from the basal levels and after intubation, and adverse effects to the study drugs were noted. Chi-square test was used to find the significance of study parameters on categorical scale among the groups. Probability values at <0.05 were considered as significant. Results: The incidence of fasciculations was 90%, 53.4% and 43.4% in groups 1, 2 & 3, respectively. Greater number of patients had grade 3 fasciculations in group 1 (20%), compared to group 2 and group 3 (3.4% and nil) respectively. The fall in blood pressure after MgSO4 was comparable among the three groups. Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP) increased by 23.5% and 18.5%, 7.9% and 4.1% and 2.8% and 2.7% in groups 1, 2 and 3, respectively at one minute. The SBP and DBP at 3rd and 5th minute stayed at statistically significant greater levels in group 1 as compared to groups 2 and 3, but were similar in groups 2 and 3 overall. The Heart Rate (HR) changes followed similar trend in all 3 groups. Incidence of feeling of warmth was highest in group three as compared to other groups. Conclusion: MgSO4 at 40 mg/kg can be the optimal dose to suppress Sch-induced fasciculations, with better attenuation of intubation associated haemodynamic changes.