The effect of magnesium sulphate pretreatment on suxamethonium-induced rise in intraocular pressure in patients undergoing surgery under general anaesthesia

Abstract

Background: Patients with increased intraocular ocular pressure (IOP) or open eye with full stomach scheduled for surgery under general anaesthesia are at the of risk of extrusion of eye content and possible regurgitation and aspiration of gastric contents. Thus prevention or reducing the rise in IOP following the administration of suxamethonium in this group of patients is crucial. Aim: This study aimed to evaluate the efficacy of MgSO4 pre-treatment on suxamethonium- induced rise in IOP during general anaesthesia in patients coming for elective general surgery. Methodology: Ninety-six ASA1 or 2 patients aged 15-65 years were recruited into two equal groups after ethics committee approval. One group received MgSO4 and the other group received normal saline. The IOP was measured and recorded at specified times up to 15 minutes after tracheal intubation. Data were analysed with the SPSS version 16. Continuous data were summarised as means and standard deviation (SD) and dichotomous data as counts and frequency. Parametric data were compared using student’s t-test and categorical data analysed using chi-square and fisher’s exact test. A P value of < 0.05 was considered as statistically significant. All statistical tests were two - sided. Result: There were significant differences in IOP changes following suxamethonium, tracheal intubation, at 5th minute, 10thminute and 15th minute post intubation with p values 0.001, <0.001, <0.001, <0.001, 0.001 respectively (independent t-test). The mean time taken to return to baseline/near baseline was shorter in the study group. There were statistical differences in the IOP, PR, SBP, DBP, and MAP after suxamethonium administration and laryngoscopy and tracheal intubation. The incidence of side effects and complications were minimal. Conclusion: This study revealed that 30 mg/kg of magnesium sulphate pretreatment minimized the increase in IOP following suxamethonium administration. It also reduced the haemodynamic response associated with laryngoscopy and tracheal intubation.