Different doses of intravenous Magnesium sulfate on cardiovascular changes following the laryngoscopy and tracheal intubation: A double-blind randomized controlled trial

Objective: Laryngoscopy and intratracheal intubation may cause acute hemodynamic instabilities due to catecholamine release. Magnesium sulfate (MgSO 4 ) prevents catecholamine release and results in bradycardia and vasodilatation, so can be used to diminish complications of laryngoscopy and intubation in doses > 50 mg/kg. The aim of this study was to compare the different doses of MgSO 4 used to improve cardiovascular instabilities due to laryngoscopy and intratracheal intubation. Methods: In this double-blind randomized controlled trial, 120 patients undergoing elective surgery were divided equally into four groups (n = 30) and received different doses of MgSO 4 as case groups (Group I: 30 mg/kg, Group II: 40 mg/kg, Group III: 50 mg/kg) or the equal volume of normal saline as a control group. The patients' hemodynamic status was recorded at baseline, before laryngoscopy and in 1, 3, 5, and 10 minutes after laryngoscopy. Bradycardia, tachycardia, hypertension, hypotension, ST-T changes, arrhythmias, and duration of extubation and laryngoscopy were also recorded. Findings: There was no significant difference in heart rate between four groups (P baseline = 0.46, P preoperation = 0.55, P 1 min = 0.86, P 3 min = 0.30, P 5 min = 0.63, P 10 min = 0.74). Systolic, diastolic and mean arterial pressures were statistically significant less at 1, 3, and 5 minutes after intubation in comparison with other times of following-up in the three groups received MgSO 4 than the control group. Conclusion: The use of MgSO 4 in doses less than 50 mg/kg can be effective to reduce cardiovascular instability related to laryngoscopy and tracheal intubation.