Effects of magnesium sulfate pretreatment on succinylcholine-facilitated tracheal intubation.

Magnesium sulfate may prevent increase in serum potassium produced by succinylcholine and cause transient hypotension. The present study was designed to evaluate the effect of magnesium sulfate on heart rate, blood pressure and hyperkalemic response following succinylcholine injection during tracheal intubation. Twenty patients, ASA class I-II, scheduled for elective surgery were equally and randomly allocated to two groups. Heart rate, blood pressure, venous and arterial potassium levels were measured immediately before intubation. Induction was achieved with fentanyl 2 ug/kg and thiopental 5 mg/kg i.v., and intubation was facilitated with succinylcholine 1.0 mg/kg i.v. In the magnesium group (group I), 60 mg/kg of magnesium sulfate was infused intravenously in 1-1.5 min immediately before succinylcholine injection. The control group (group II) received an equal volume of normal saline in the same way. Heart rate, blood pressure, venous and arterial potassium levels were measured at 1, 3, 5 and 10 minutes after intubation. The results showed that magnesium sulfate could attenuate the hypertensive response at 1 minute and the hyperkalemic response at 1 and 3 minutes following succinylcholine-facilitated intubation; the tachycardiac response at 1 minute after intubation could not be reduced by this agent. We concluded that bolus infusion of magnesium sulfate may be of help in reducing the hypertensive response during laryngoscopy and intubation.