The immediate cardiovascular effects of pancuronium, alcuronium and tubocurarine in man

Previous studies in man on the cardiovascular effects of the muscle relaxant pancuronium have been conflicting. Kelman & Kennedy 1 found a significant increase in heart rate, blood pressure and cardiac output. McDowell & Clark2 and Kolliker3, reported a fall in blood pressure with no change in heart rate. Baird & Reid4 and Fastner & Agostons, found no significant effect on the heart rate and blood pressure and Loh6 found that pancuronium increased both blood pressure and heart rate. The discrepancies between their reports can be reasonably attributed to differences in methods of study. There were differences in premedication and in the degree of surgical stimulation. Measurements were sometimes made during endotrachea1 intubation7, which is a procedure well known to cause tachycardias and several patients were receiving digitalis. Arterial carbon dioxide levels were not always controlled and some studies were performed upon patients receiving volatile anaesthetic agents. There have also been discrepancies too, for similar reasons, in reports on the cardiovascular effects of tubocurarine and alcuroniumg13. In evaluating a new drug it is useful to compare it with established agents which fulfil similar roles in clinical practice. In this study pancuronium, a relatively new drug, has been compared with tubocurarine and alcuronium administered in similar circumstances. There are no previous reports of this nature so far as the authors are aware and, to our knowledge, no data on the absolute level of cardiac output in man following the administration of muscle relaxants has been revealed by a study of the literature.