This study evaluated the effect of sevoflurane anesthesia on neuromuscular blockade with rocuronium in dogs. Six healthy beagle dogs were anesthetized four times with a minimum 14-day
washout period. On each occasion, the dogs were administered 1.25-, 1.5-, 1.75-, or 2.0-fold of the individualized minimum alveolar concentration (MAC) of sevoflurane and received an
infusion of rocuronium (0.5 mg/kg followed by 0.2 mg/kg/hr) for 120 min. Neuromuscular function was monitored with acceleromyography and train-of-four (TOF) stimulation of the left hind
limb. Time to achieve TOF count 0 (onset time), time from the onset of neuromuscular blockade to the reappearance of TOF count 4 (blockade period), and time from the onset of rocuronium
infusion to attaining a 70 or 90% TOF ratio (TOFR
70
or TOFR
90
) were recorded. There were no significant differences in the onset time, blockade period, and plasma
rocuronium concentration between the sevoflurane MAC multiples. The TOFR
70
and TOFR
90
were dose-dependently prolonged with the sevoflurane MAC multiples. There were
significant differences in the TOFR
70
and TOFR
90
between the 1.25 sevoflurane MAC (median: 55 and 77.5 min, respectively) and 1.75 sevoflurane MAC (122.0 and 122.6 min;
P
=0.020 and
P
=0.020, respectively), 1.25 sevoflurane MAC and 2.0 sevoflurane MAC (126.0 and 131.4 min;
P
=0.020 and
P
=0.020), and 1.5 sevoflurane MAC (97.5 and 121.3 min) and 2.0 sevoflurane MAC (
P
=0.033 and
P
=0.032). In dogs, sevoflurane anesthesia
produced dose-dependent prolongation of recovery from neuromuscular blockade produced by rocuronium.