Comparison of the effects of atracurium and tubocurarine on heart rate and arterial pressure in anaesthetized man.

The effects of atracurium and tubocurarine on heart rate and arterial pressure were studied in anaesthetized patients. A bolus of 0.6 mg kg-1 of either atracurium or tubocurarine was administered. Following atracurium, the change in heart rate was minimal (mean +/- SEM: -1.6 +/- 1.3 beat min-1) whereas after tubocurarine heart rate was increased (mean +/- SEM: +9.9 +/- 1.9 beat min-1). Atracurium produced a transient decrease in arterial pressure in 28% of subjects; by the 4th min after its injection the change was minimal (mean +/- SEM: -1.5 +/- 1.1 mm Hg). Tubocurarine produced an initial decrease in mean arterial pressure in all patients, of up to 50% of control values. In the 4th min following its injection arterial pressure was still significantly different from control (mean +/- SEM: -10 +/- 1.5 mm Hg). Endotracheal intubation caused an increase in arterial pressure in all subjects. It is concluded that atracurium has minimal effects on heart rate and arterial pressure when compared with tubocurarine. It does not appear to have a vagal blocking action.