All anesthetics (remifentanil, propofol, desflurane, and sevoflurane) were decreased only in the event of hypotension that was unresponsive to intraoperative fluid replacement, or bradycardia. When clinically indicated, a vasopresser or atropine was used, as indicated. Anesthetic agents were increased to control the hemodynamic responses to surgical stimulation, which was defined as mean arterial pressure grid within 20% of baseline and/or heart rate grid within 90 beats/minute, or clinical finds of light anesthesia. In the volatile anesthetic group, additional bolus doses of fentanil 1mg/kg were administered; in the PIVA group, remifentanil infusion was increased by increments of 0.1mg/kg/minute. At the end of surgery, all anesthetics were terminated simultaneously without tapering, and ventilation was controlled until the return of spontaneous ventilation.

The mean age of the patients studied was 34 to 42 years and the mean weight was 69 to 79 kilograms. Surgical procedures lasted 54 to 74 minutes, while duration of anesthesia lasted 108 to 129 minutes. By chance the patients of the sevoflurane group had the heaviest mean weight, duration of surgery, and duration of anesthesia.

The patients in the remifentanil group showed significantly faster emergence and awakening in the early phase of recovery than patients receiving desflurane or sevoflurane, as measured by times to eye opening, times to squeeze fingers, state name, and state birthday. No difference could be demonstrated between desflurane and sevoflurane except minimally but significantly faster eye opening after desflurane. At 30 minutes after the termination of anesthesia, significantly more patients in the remifentanil and desflurane groups gave correct responses on the DSST than in the sevoflurane group, whereas at 60 minutes only remifentanil patients had more rapid responses. Ninety minutes after anesthesia administration no difference could be demonstrated on this test among the 3 groups, and there was no significant difference on the Trieger Dot Test between groups. No difference could be demonstrated among the 3 groups with regard to postoperative pain intensity, need for analgesics, nausea/vomiting, or satisfaction with anesthesia, while significantly more patients retained chest wall rigidity during the induction of anesthesia with remifentanil.

The authors believe that fast awakening in the remifentanil group was observed because remifentanil provided earlier return of cognitive function. When combined with remifentanil, propofol converts to a drug whose pharmacokinetics limit the rate of recovery. Because of this, the authors suggest that intermediate recovery from remifentanil-based anesthesia might be accelerated with small concentrations of one of the new inhaled anesthetics rather than propofol, particularly for long operative procedures. They suggest that a similar effect could be achieved by reducing the propofol and increasing the remifentanil concentrations. However, the propofol concentrations used here are probably at the lower limit of those that will provide consistent loss of consciousness. Postoperative pain management may at least theoretically be a problem when remifentanil is used as as the surgical opioid.

In this study, the author has prevented postoperative pain by administering rectal paracetimal and a long acting opioid, piritramid, in the recovery room. All patients had an average of 40 mg of meperidine for shivering in all groups and ? as well. However, the recovery picture may have been substantially clouded by the other drugs that were given, as patients were given benzodiazapine the day before and the day of surgery. The patients in the inhaled agent groups received, at induction, fentanil 2 mg/kg and then 6 to 7 additional boluses of fentanil 1mg/kg for a total of 8 to 9 mg/kg over the course of these 108 to 129 minute anesthetics. It is very possible that this substantial dose of perioperative fentanil was in a large part responsible for the relatively poor wake-up scene in the inhaled agent groups.

It should also be noted that this study does not evaluate the relative cost of the anesthetics given. The authors discuss their findings in terms of rapid recovery issues, including fast tracking. Also, in contrast to common clinical practice, all anesthetics used in the study were left at depth until they were turned off at the end of the anesthetic, without tapering.

ABSTRACT Recovery of cognitive function after remifentanil-propofol anesthesia: a comparison with desflurane and sevoflurane anesthesia AUTHORS: Larsen B, Seitz A, Larsen R. SOURCE: Anesth Analg 2000 Jan;90(1):168-74. ABSTRACT: We compared the recovery characteristics of remifentanil, desflurane, and sevoflurane when used for anesthesia in elective operative procedures. Sixty ASA physical status I and II patients, aged 18-65 yr, were randomly assigned to receive remifentanil-propofol, desflurane-N2O, or sevoflurane-N2O anesthesia. Before the induction of anesthesia, the patients of the desflurane and sevoflurane groups received fentanyl 2 microg/kg. In all groups, anesthesia was induced with propofol and maintained either with remifentanil 0.25 microg x kg(-1) x min(-1), desflurane, or sevoflurane 0.85 MAC with 65% nitrous oxide in oxygen. Anesthetics were titrated to achieve an adequate level of surgical anesthesia and to maintain mean arterial pressure within 20% of baseline values. Early recovery times and a modified Aldrete Recovery Score > 9 were recorded. Trieger Dot Test and Digit Substitution Test (DSST) were performed the day before surgery and in the postanesthesia care unit to evaluate intermediate recovery. The remifentanil-propofol group had a significantly faster emergence than desflurane or sevoflurane, with no difference between both inhaled anesthetics. Thirty min after anesthesia administration, patients in the remifentanil-propofol and in the desflurane groups gave significantly more correct responses in the DSST compared with sevoflurane (remifentanil 87%, desflurane 83%, sevoflurane 56%), the impairment in the sevoflurane patients corresponding to the effects of a blood alcohol level of approximately 0.1% and, thus, being of clinical importance. Ninety minutes after anesthesia administration, no significant difference could be demonstrated among the groups in the DSST scores. Emergence and return of cognitive function was significantly faster after remifentanil-propofol compared with desflurane and sevoflurane up to 60 min after anesthesia administration. IMPLICATIONS: We compared awakening and intermediate recovery times after remifentanil-propofol anesthesia to desflurane-N2O and sevoflurane-N2O anesthesia. Emergence and return of cognitive function was significantly faster after remifentanil-propofol compared with desflurane and sevoflurane up to 60 min after anesthesia administration.