Total i.v. anaesthesia with propofol-alfentanil or propofol-fentanyl

In combination with propofol, alfentanil was compared with fentanyl for total i.v. anaesthesia in 29 women (ASA classes I, II) admitted for elective hysterectomy. Infusion rates of propofol and fentanyl were determined from the literature and from pilot studies, while alfentanil was given according to a computer program. Dosage was: propofol, bolus 1.5 mg kg-1, infusion 9 mg kg-1 h-1 for 10 min and thereafter 6 mg kg-1 h-1; fentanyl, bolus 7.5 micrograms kg-1, infusion 15 micrograms kg-1 h-1 reduced successively to 1.8 micrograms kg-1 h-1; alfentanil, bolus 60 micrograms kg-1, infusion 240 micrograms kg-1 h-1 reduced successively to 100 micrograms min-1. Induction was smooth and maintenance easy to manage in both groups. Plasma concentrations were stable with a ratio of alfentanil to fentanyl of 100:1. Recovery times were equal and short, but recovery tests performed 3 h after operation showed that alfentanil produced a greater effect on ability to concentrate and fine co-ordination.