Neuromuscular effects of rocuronium bromide during isoflurane and propofol anaesthesia

Abstract

Rocuronium is a new monoquaternary aminosteroidal neuromuscular blocking drug with a duration of action similar to that of vecuronium but with a more rapid onset of action. In this study we determined the neuromuscular blocking effects of rocuronium under isoflurane and propofol anaesthesia. Following hospital ethics committee approval and patient informed consent 24 ASA I-II patients scheduled for elective surgery were included in our study. Patients were randomly allocated to one of two equal groups. While induction of anaesthesia was performed by propofol 2.5 mg kg−1 in both groups, anaesthesia was maintained by nitrous oxide 67% and isoflurane 1-1.5% in oxygen in Group I and by propofol infusion at a rate of 10 mg kg−1 min−1 in Group II. Two minutes after the administration of rocuronium 0.4 mg kg−1 IV endotracheal intubation was performed and intubation conditions were assessed and scored as excellent, good, poor and inadequate. Whenever T1 returned to 25% control additional doses of rocuronium 0.2 mg kg−1 were given. Supramaximal stimuli, duration 0.2 m and frequency 2 Hz were delivered in a train-of-four (TOF) sequence at 12 s intervals to the ulnar nerve at the wrist via surface electrodes. The times were measured from completion of injection. The onset time (T1 max), duration of block (T1 25%), time to maximal block after the second dose (T2 max), the duration of action of maintenance doses (T2 25%) and recovery times (T2 70-25%) were the values measured. ANOVA was used for analysis, and P<0.05 was considered significant. While the intubation conditions were excellent or good in 50% patients in Group I and 80% in Group II. No significant differences were observed in T1 max, T1 25%, T2 max and recovery times between the groups. In conclusion it has been demonstrated that rocuronium is an intermediate-acting neuromuscular blocking drug with a rapid onset of action and the neuromuscular action is not significantly affected by isoflurane or propofol anaesthesia. (Table 20)Table 20: (abstract 69). Time course of action of rocuronium with isoflurane and propofol (min ± SE)