ABSTRACT : Whether magnesium sulphate combined with vecuronium priming shortens the onset of neuromuscular blockade, compared with these methods used alone.

METHODS : Hundred patients scheduled for general anaesthesia were randomly allocated to one of four groups of 25 each: controls were given 0.1 mg.kg−1 vecuronium; patients in the prime group were given 0.01 mg.kg−1 vecuronium three minutes before a further dose of 0.09 mg.kg−1 vecuronium; patients in the magnesium group were given an infusion of 50 mg.kg−1magnesium sulphate before vecuronium and patients in the magnesium and prime group were given both the magnesium sulphate and the priming dose of vecuronium. Tracheal intubation was attempted after train of four stimulus showed only one twitch. The time to onset of neuromuscular blockade was the primary outcome; duration of blockade and tracheal intubating conditions were also measured. Statistical analysis was done using ANOVA test and Post Hoc test.

RESULTS : The magnesium and prime group had the shortest mean onset time and best tracheal intubating conditions.

CONCLUSIONS : The combination of magnesium sulphate and vecuronium priming accelerated the onset of neuromuscular blockade and improved intubating conditions, compared with either magnesium sulphate or priming used alone.