PHARMACOKINETICS OF PROPOFOL DURING CONSCIOUS SEDATION USING TARGET-CONTROLLED INFUSION IN ANXIOUS PATIENTS UNDERGOING DENTAL TREATMENT

Infusion of propofol by a target-controlled infusion (TCI) system is e ffective in achieving conscious sedation for anxious patients presenti ng for dental surgery. It is a common clinical observation that anxiou s patients require more anaesthetic drugs than non-anxious individuals . In study 1 we have defined blood propofol concentrations necessary f or conscious sedation in both anxious (n = 23) and non-anxious (n = 18 ) patients. The pump performance of the TCI system, using Gepts' pharm acokinetic model, was evaluated in these two patient groups. Subsequen tly, clearance of propofol was compared in the two groups. Mean measur ed venous serum propofol concentrations obtained between 20 and 35 min after the optimal sedation level was reached were 1.6 (so 0.2) mu g m l(-1) in the anxious patients compared with 1.7 (0.3) mu g ml(-1) in t he control group (study 1 and 1.4 (0.27) mu g ml(-1) in study 2. The p ump systematically overpredicted measured propofol concentrations in b oth groups (study 1). There was no significant difference in propofol clearance between the two groups. In study 2, an optimized set of micr oconstants was derived which should more accurately predict the pharma cokinetic profile of the anxious population and this set was tested pr ospectively in another group of 12 anxious dental patients. Bias and p recision with the optimized kinetic set were significantly less than t he values obtained in study 1. We conclude that there was no significa nt pharmacokinetic differences between anxious and non-anxious subject s receiving subanaesthetic doses of propofol for conscious sedation.