AnesthesiaWeb - Lit Reviews- A randomized multicenter study of remifentanil compared with alfentanil, isoflurane, or propofol in anesthetized pediatric patients undergoing elective strabismus surgery

July 1997

A randomized multicenter study of remifentanil compared with alfentanil, isoflurane, or propofol in anesthetized pediatric patients undergoing elective strabismus surgery.

Davis PJ, Lerrman J, Suresh S, McGowan FX, Cote CJ, Landsman I, Henson LG.

Anesth Analg 1997: 84:982-9.

[ see abstract below ]

Davis et al performed the first multicenter trial of remifentanil in a pediatric population using propofol, alfentanil, and isoflurane as comparators. It was of interest that there was no difference in time to extubation, time to purposeful movement, time to hospital discharg or incidence of vomiting; the incidence of postoperative hypoxemia and need for naloxone was higher in the alfentanil group. There was one very important pharmacodynamic difference with remifentanil which was higher pain scores when compared with alfentanil, but the incidence of pain medication requirement was the same as for propofol or isoflurane.

The infusion rate used for this study was likely higher than subsequent adult studies suggest, which may have confounded the patient wake-up data, but certainly did not influence the need for postoperative opioid. I admit that I was one of the investigators involved in this study so that my comments may not be totally objective, however this involvement also allows me to make clinical observations.

I was very impressed with the rapidity of onset of intense opioid effect and the rapidity with which it wore off. My further impression is that it will take a fair amount of clinical experience to become facile with its use and the nuances associated with its use.

It is very important to either provide a regional block so that the patient is pain free upon awakening or to transition to longer acting opioids so as to avoid a patient waking up in pain. Patients wake up very rapidly indeed. During the case, special attention needs to be paid to the patency and continued smooth running of the intravenous through which remifentanil is being administered; alterations in flow rate or kinking of the catheter may result in a suddenly "awake" patient.

In children it may be important to use a pump to run maintenance fluid and another "piggy backed" with the remifentanil. Most interesting to me was the fact that despite in retrospect our using two and perhaps three times the necessary dose of remifentanil, the patients went from apnea with pinpoint pupils to wide awake on average within 10 minutes.

The area of interest now for us as pediatric anesthesiologists is to determine the role this drug will play in our care of children. We have yet to gain widespread use in cardiac, neurosurgical, and other procedures where an intense but limited opioid effect is desired. Since the early studies have focused primarily on pharmacokinetics and cost savings, clinical application studies will be important.

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ABSTRACT

Remifenatnil 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 the 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 micrograms/kg over 30-60 s, followed by a constant infusion of 1.0 micrograms ^. kg ^-1 ^. min^-12, 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 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 times to PACU and hospital discharge among groups. Patients who received remifentatil 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. It's hemodynamic and recovery profile appear similar to other comparable drugs. Based on previous phamacokinetic studies, the 1.0 micrograms. 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.