Effects of Intravenous Magnesium Sulfate and Lidocaine on Hemodynamic Variables Following Direct Laryngoscopy and Intubation in Elective Surgery Patients

Laryngoscopy and intubation incur hemodynamic changes like increase in heart rate, arterial blood pressure, pulmonary artery pressure, wedge capillary pressure and arrhythmias. Anesthesiologists are continually in search of ways to alleviate such complications. Several medicinal methods have been suggested that serve the purpose including the administration of intravenous magnesium sulfate to minimize these unfavorable responses. This study compares the effects of intravenous administration of lidocaine and magnesium sulfate on unwanted hemodynamic responses following laryngoscopy and intubation in elective surgery candidates. This randomized double-blind clinical trial was conducted on 60 ASA-I and ASA-II candidates who received 60 mg/kg (based on Lean Body Mass) magnesium sulfate or lidocaine randomly before intubation. Values of systolic and diastolic blood pressures, mean arterial pressure, and heart rate were recorded for both groups during the 5 minutes following administration, and compared with baseline values. In both groups, systolic blood pressure increased compared to the baseline value. However, there was a significant difference between the two groups as this increase occurred within the first 3 minutes in the lidocaine group, while within the first minute in the magnesium sulfate group. The increase in diastolic blood pressure was not significant. But there was a significant difference in the mean arterial pressure increase between the two groups since in the magnesium sulfate group this increase occurred in the first minute whereas in the lidocaine group it occurred during the first two minutes. There was no significant difference in the heart rates after intubation between the two groups. Magnesium sulfate is more effective than lidocaine in controlling hemodynamics, although it may increase the heart rate.