INFLUENCE OF PREANESTHETIC MEDICATION ON TARGET PROPOFOL CONCENTRATION USING A DIPRIFUSOR TCI SYSTEM DURING AMBULATORY SURGERY

The effects of pre-anaesthetic medication on target propofol concentra tion, induction dose, time to induction, and discomfort on infusion we re studied in 45 female patients undergoing ambulatory gynaecological procedures using 'Diprifusor' target controlled infusion of propofol. The patients were randomly allocated to receive either no premedicatio n (group 1) or premedication with diazepam alone (group 2) or in combi nation with alfentanil (group 3). Induction was more successful in pre medicated than unpremedicated patients with an initial target propofol concentration of 4 mu g.ml(-1) (87% in group 2 and 93% in group 3 vs. 38% in group 1, p < 0.01). Premedication was also associated with the requirement of a lower mean target concentration for induction, a low er induction dose and a shorter time to induction. There were no signi ficant between-group differences in discomfort on infusion or target c oncentration during maintenance. For short ambulatory procedures, the recommended initial target concentration of propofol is 4 mu g.ml(-1) in premedicated and 6 mu g.ml(-1) in unpremedicated patients.