• C A Shanks, R J Fragen, and D Ling.
• Department of Anesthesia, Northwestern University, Chicago, Illinois 60611.
• Anesthesiology. 1993 Apr 1;78(4):649-51.

BackgroundRocuronium (ORG 9426) is a new nondepolarizing neuromuscular blocking agent with a rapid onset and an intermediate duration of action. This study obtains the infusion requirements of rocuronium in 30 patients in whom anesthesia was maintained with barbiturate-nitrous oxide-opioid, nitrous oxide and enflurane, or nitrous oxide and isoflurane.MethodsFor all 30 patients, anesthesia was induced with intravenous thiopental and fentanyl, followed by 0.45 mg/kg rocuronium. Patients were randomly allocated to receive either: 1) nitrous oxide in 40% oxygen supplemented with fentanyl, thiopental, and droperidol (balanced anesthesia), 2) 1.25 MAC enflurane-nitrous oxide, or 3) 1.25 MAC isoflurane-nitrous oxide. Once blockade had recovered to 95% depression of twitch height, muscle relaxation was maintained by continuous infusion of rocuronium, adjusted to maintain mechanical twitch response at 95% depression.ResultsAt 90 and 120 min, the enflurane and isoflurane groups had lower infusion requirements than those receiving barbiturate-nitrous oxide-opioid anesthesia (P < 0.02), but these did not differ significantly between the two volatile agents. Final infusion requirements (mean +/- SD) were 9.8 +/- 3.7, 5.9 +/- 3.1, and 6.1 +/- 2.7 micrograms.kg-1.min-1 for the groups receiving barbiturate-nitrous oxide-opioid, enflurane, and isoflurane anesthesia, respectively. Spontaneous recovery began soon after termination of the infusion; in all patients, twitch tension equaled 10% of control within 5 min.ConclusionsThe infusion requirements to maintain 95% twitch depression approximated 10 micrograms.kg-1.min-1 during barbiturate-nitrous oxide-opioid anesthesia. These requirements were reduced by 40% during anesthesia involving enflurane or isoflurane.

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