Continuous infusion of alfentanil.

The administration of alfentanil by continuous infusion as supplementation to nitrous oxide for shortlasting anesthesias has been studied in 51 patients. Anesthesia was induced with thiopental 4 to 5 mg/kg-1. Analgesia was performed by a continuous infusion of alfentanil (0.1 mg.ml-1 in glucose 5%) preceded by a bolus injection of 0.5 mg alfentanil i.v. Supplementations of 0.25 mg alfentanil i.v. were given if indicated. The patients were divided into 4 groups, according to the rate of infusion (group I: 4 mg.hr-1; group II: 5 mg.hr-1) and to the addition of either droperidol (group III) or domperidone (group IV). Anesthesia was satisfactory in all cases. Alfentanil given by continuous infusion (4 mg/hr-1) preceded by a bolus injection (0.5 mg) provided a good basic analgesia. With this method of administration the awakening time was shorter and less analgesic was needed than after incremental dosages of alfentanil. Droperidol, almost abolished nausea and vomiting postoperatively. It, however, clearly potentiated the effect of alfentanil. Domperidone given instead of droperidol had no or little effect on postoperative nausea and vomiting.