Practical aspects of alfentanil infusion.

: The administration of alfentanil by infusion appears to present advantages for the induction and maintenance of anaesthesia during general surgery lasting over 1 h. The following dosage scheme is proposed: a loading dose of 100 micrograms kg-1, given either in one or two doses, or as a fast infusion administered over 10 min, followed by a maintenance infusion at a rate of 1 microgram kg-1 min-1. During maintenance anaesthesia, the infusion rate should be the lowest possible compatible with adequate analgesic effect, and should be further decreased 15-20 min before the projected end of surgery. Fine control of the opioid effect can be achieved with small increments of 7-15 micrograms kg-1 or by alterations of the alfentanil infusion rate. Breathing should be carefully monitored during the post-operative phase. Dedicated syringe pumps have been designed to avoid laborious calculations of the infusion rates and allow simple, rapid changes of the infusion rate.