To evaluate the influence of sevoflurane on the dose-response relation
ship and on the time-course of the effect of rocuronium, 60 adult pati
ents undergoing elective plastic surgery were randomly allocated to ei
ther the control or the sevoflurane group. Anaesthesia was maintained
with 60% nitrous oxide in oxygen and thiopentone in the control group
and with 60% nitrous oxide in oxygen and an end-tidal concentration of
1.75% sevoflurane in the sevoflurane group. Neuromuscular function wa
s assessed mechanomyographically with train-of-four stimulation at the
wrist every 12s and the percentage depression of the first twitch of
the train-of-four was used as the study parameter. The dose-response r
elationship of rocuronium in the two groups was determined by the cumu
lative dose-response technique. The dose-response curve of rocuronium
in the sevoflurane group was shifted to the left compared to the contr
ol group, indicating a potentiation of rocuronium-induced neuromuscula
r block. The effective doses of rocuronium required to produce 50%, 90
% and 95% twitch depression in the sevoflurane group were decreased by
30.5%, 26.7% and 25.2%, respectively, compared to the control group.
Following the administration of a total dose of rocuronium of 400 mu g
.kg(-1), the duration of action of and the recovery from, rocuronium w
ere both significantly prolonged by sevoflurane. There were significan
t differences in the duration of peak effect, clinical duration, recov
ery index and the total duration of action between the control and the
sevoflurane groups.