The Influence of Two Different Doses of Magnesium Sulfate on Intraocular Pressure Variations after Injection of Succinylcholine and Endotracheal Intubation: A Prospective, Randomized, Parallel Three-Arm, Double-blind, Placebo-controlled Clinical Trial

BACKGROUND: The use of succinylcholine for rapid sequence induction in patients with open globe injuries may be detrimental to the eye. AIM: The aim of this study is to determine if the premedication with magnesium sulfate (MgSO(4)) could attenuate the increase in intraocular pressure (IOP) associated with succinylcholine injection and intubation. SETTING: Operation theaters in a tertiary care University Hospital between December 2014 and July 215. DESIGN: This was a prospective, randomized, parallel three-arm, double-blind, placebo-controlled clinical trial. PARTICIPANTS: One hundred and thirteen patients’ physical status ASA Classes I and II underwent elective cataract surgery under general anesthesia. PATIENTS AND METHODS: These patients allocated into three groups: Group C (control group) received 100 ml normal saline, Group M1 received 30 mg/kg MgSO(4) in 100 ml normal saline, and Group M2 received 50 mg/kg MgSO(4) in 100 ml normal saline. IOP, mean arterial pressure (MAP), and heart rate (HR) reported at 5-time points related to study drug administration. In addition, any adverse effects related to MgSO(4) were recorded. Intragroup and between-groups differences were examined by analysis of variance test. RESULTS: We noticed a significant decrease in IOP in M1 (n = 38) and M2 (n = 37) groups as compared with C group (n = 38) after study drugs infusion, 2 and 5 min after intubation, P < 0.001. While the difference between M1 and M2 groups was insignificant, P = 0.296 and P = 0.647, respectively. There was a significant decrease in MAP and HR in M1 and M2 groups as compared with C group 2 and 5 min after intubation, P = 0.01. While the difference between M1 and M2 groups was insignificant, P = 1. CONCLUSION: MgSO(4) 30 mg/kg as well as 50 mg/kg effectively prevented the rise in IOP, MAP, and HR associated with rapid sequence induction by succinylcholine and endotracheal intubation.