A randomized multicenter study of remifentanil compared with alfentanil, isoflurane, or propofol in anesthetized...

Remifentanil hydrochloride is a new, ultrashort-acting opioid metabolized by nonspecific plasma and tissue esterases. We conducted this multicenter study to examine the hemodynamic response and recovery profile of premedicated children undergoing strabismus repair who were randomly assigned to receive one of four treatment drugs (remifentanil, alfentanil, isoflurane, or propofol) along with nitrous oxide and oxygen for maintenance of anesthesia. Induction of anesthesia was by nitrous oxide, oxygen, and halothane or nitrous oxide, oxygen, and propofol. Anesthesia was then maintained with remifentanil 1.0 microgram/kg over 30-60 s, followed by a constant infusion of 1.0 microgram.kg-1.min-1, alfentanil 100 micrograms/kg bolus followed by a constant infusion of 2.5 micrograms.kg-1.min-1, propofol 2.5 mg/kg bolus followed by a constant infusion of 200 micrograms.kg-1.min-1, or isoflurane 1.0 minimum alveolar anesthetic concentration. The infusions of the anesthetics and the administration of the inhaled gases were adjusted clinically by predetermined protocols. Elapsed time intervals from the end of surgery to the time the patients were tracheally extubated and displayed purposeful movement, as well as the time the patients met the postanesthesia care unit (PACU) and hospital discharge times, were recorded. Heart rate and systolic and diastolic blood pressure were measured at fixed intervals. In addition, cardiovascular side effects (bradycardia, hypotension, and hypertension) as well as vomiting, pruritus, agitation, and postoperative hypoxemia were also noted. There were no significant differences in patient demographics among the treatment groups. There was no difference in the early recovery variables (times to extubation and purposeful movement) or the times to PACU and hospital discharge among groups. There were significant differences in side effects among the groups. Patients who received remifentanil had higher PACU objective pain-discomfort scores than those who received alfentanil and propofol. Patients anesthetized with alfentanil had a greater incidence in the use of naloxone and a greater incidence of postoperative hypoxemia compared with those anesthetized with remifentanil. The incidence of postoperative hypoxemia was the same for remifentanil, propofol, and isoflurane groups. There were no significant differences in the incidence of emesis among the four groups, and all four groups had similar hemodynamic profiles. We conclude that remifentanil appears to be an effective drug for anesthesia. Its hemodynamic and recovery profile appear similar to other comparable drugs. Based on previous pharmacokinetic studies, the 1.0 microgram.kg-1.min-1 infusion may be twice the 50% effective dose observed in adults. In this study, the relative "overdose" of remifentanil was well tolerated and did not prolong recovery.