EVALUATION OF THE PREDICTIVE PERFORMANCE OF A DIPRIFUSOR TCI SYSTEM

The predictive performance of a 'Diprifusor' target controlled infusio n system for propofol was examined in 46 patients undergoing major sur gery, divided into three age groups (18-40, 41-55 and 56-80 years). Me asured arterial propofol concentrations were compared with values calc ulated (predicted) by the target controlled infusion system. Performan ce indices (median performance error and median absolute performance e rror) were similar in the three age groups, with study medians of 16.2 % and 24.1%, respectively. Mean values for 'divergence' and 'wobble' w ere -7.6%.h(-1) and 21.9%, respectively. Measured concentrations tende d to be higher than calculated concentrations, particularly following induction or an increase in target concentration. The mean (SD) propof ol target concentration of 3.5 (0.7) mu g.ml(-1) during maintenance wa s lower in older patients, compared with higher target concentrations of 4.2 (0.6) and 4.3 (0.7) mu g.ml(-1) in the two younger age groups, respectively. The control of depth of anaesthesia was good in all pati ents and the predictive performance of the 'Diprifusor' target control led infusion system was considered acceptable for clinical purposes.