COMPARISON OF COMPUTER-CONTROLLED ADMINISTRATION OF PROPOFOL WITH 2 MANUALLY CONTROLLED INFUSION TECHNIQUES

Ninety women were studied in order to compare dose requirements and qu ality of anaesthesia between target-controlled infusion and two manual ly controlled infusion schemes for propofol administration: group I re ceived target-controlled infusion for induction (4 mu g.ml(-1) target blood concentration, increased by 2 mu g.ml(-1) after 3 min if conscio usness not lost), groups II and III received an induction bolus of pro pofol at infusion rates of 1200 or 600 ml.h(-1), respectively, until l oss of consciousness. Anaesthesia was maintained with propofol target- controlled infusion in group I or by constant rate infusion in the oth er two groups. Computer simulations were used to calculate blood and e ffect-site propofol concentrations. Mean induction times (SD) were 78 (65) s in group I versus 51 (10) s and 62 (12) s in groups II and III, respectively (p < 0.05 between groups II and III). Mean induction dos es were: 1.31 (0.44), 2.74 (0.56) and 1.77 (0.43) mg.kg(-1) and mean m aintenance doses were 13.4 (3.55), 9.32 (1.71) and 9.97 (1.53) mg.kg(- 1).h(-1) in groups I, II and III, respectively (p < 0.05 between all g roups). There was a lower incidence of apnoea in group I than in group s II and III. There were no significant differences between the groups in other objective parameters of anaesthetic quality studied. Compute r simulations showed an 'overshoot' in propofol blood and effect-site concentration with manual induction and significantly higher maintenan ce levels with target-controlled infusion.