Cardiovascular effects of an intubating dose of rocuronium 0.6 mg kg-1 in anaesthetized patients, paralysed with vecuronium

We have studied, in adult patients, ASA I-II, the cardiovascular effects ofan intubating dose of rocuronium 0.6 mg kg-1. After induction, patientswere paralysed with vecuronium and the trachea intubated. Heart rate (HR)and non-invasive mean arterial pressure (MAP) were measured every 1 min.After stabilization of HR and MAP, defined as < 3% change over threemeasurements, rocuronium (n = 20) or saline (n = 10) was injected atrandom. Mean HR increased initially from 66.6 to 72.1 beat min-1, 4 minafter rocuronium, and then decreased gradually to 69.6 beat min-1, that isa net increase of 3.3 beat min-1 over 10 min (P < 0.001), whereas aftersaline there was a gradual decrease from 65.8 to 60.9 beat min-1 (P <0.001) over 10 min. From the third minute, HR was significantly higher inthe rocuronium group. Mean MAP decreased in both groups within 10 min to asimilar extent after rocuronium and saline, that is from 74.9 to 72.1 mm Hgand from 74.7 to 72.2 mm Hg, respectively (both P < 0.001). There wereno differences in MAP at any time between the rocuronium and saline groups.We conclude that an intubating dose of rocuronium, in the absence ofhaemodynamic effects related to paralysis itself, resulted in a limitedincrease in HR without change in MAP, probably because of its weakvagolytic activity.