The effect of isoflurane versus balanced anesthesia on rocuronium's pharmacokinetics and infusion requirement.
OBJECTIVE
To compare the effects of two anesthetic techniques, balanced and isoflurane anesthesia, on the response to an intubating dose and an infusion of rocuronium, and on rocuronium's pharmacokinetics.


METHODS
Randomized, open-label study.


METHODS
A university-affiliated hospital.


METHODS
Twenty-two healthy adults undergoing elective surgery.


METHODS
The patients were anesthetized with a balanced technique (nitrous oxide, fentanyl, midazolam) or isoflurane (nitrous oxide, isoflurane 0.5-1.0%). Rocuronium was administered initially as a 500-micrograms/kg bolus, then by infusion to maintain approximately 86-94% depression of twitch tension. Plasma samples to determine rocuronium concentrations were obtained before, during, and after the infusion. Pharmacokinetics were determined using a population-based approach.


RESULTS
Onset time and initial recovery after the bolus dose were similar for the two groups. Infusion requirements also were similar. Plasma clearance was greater during isoflurane than during balanced anesthesia (4.48 vs 3.49 ml/kg/min). Distribution clearances and volumes of distribution were similar for the two groups.


CONCLUSIONS
The similarity of response to an intubating dose and an infusion of rocuronium suggests that clinicians need not alter the dose or rate of rocuronium administration during isoflurane anesthesia with a of duration less than 1 hour. However, the greater clearance of rocuronium, in light of the similarity of infusion requirements, suggests that isoflurane potentiates rocuronium compared with balanced anesthesia.
Larijani
G E
GE
Department of Anesthesiology, Medical College of Pennsylvania, USA.
Gratz
I
I
Afshar
M
M
McDonald
P A
PA
Fisher
D M
DM
D000328:Adult; D000732:Androstanols / Q000008:administration & dosage / Q000493:pharmacokinetics*; D000762:Anesthesia Recovery Period; D000768:Anesthesia, General; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007530:Isoflurane / Q000494:pharmacology*; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D000077123:Rocuronium
D000732:Androstanols; D003473:Neuromuscular Nondepolarizing Agents; D007530:Isoflurane; D000077123:Rocuronium