The performance of two ke0 values based on the time to peak of bispectral index and auditory evoked potential index for target-controlled effect-site concentration

Background Our previous study found that calculated ke0 of propofol from the peak time of auditory evoked potential index (AAI) is different from bispectral index (BIS). In this study, the authors want to validate the performance of two ke0s for target-controlled effect site concentration infusion in Chinese patients. Methods Eighty-six healthy unpremedicated patients received propofol via TCI for 14-min at a target concentration of 4.2 mu g/ml. The plasma concentration was computed using the pharmacokinetics of Marsh in all three groups. The TCI device controlled the plasma concentration in group I and the effect site concentration with the ke0s of 0.62min(-1) and 1.83min(-1) in group II and III, respectively. The time course of propofol was measured using BIS. Blood pressure, heart rate and the time of loss of consciousness (LOC) were measured. Simulation of effect site concentrations was performed at LOC using two ke0 values in group I. Results The time course of propofol drug effect was better predicted in group III than group II. The median time to LOC 75s in group I was significant longer than 40s in group II, III respectively (p<0.05). With ke0 of 1.83min(-1), the simulated effect site concentration 3.66 mu g/ml at LOC in group I had were not different to the target-controlled effect-site concentration 3.16 mu g/ml at LOC in group III (p=NS). The observed time to the lowest systolic pressure and the mean maximum decreasing amplitude of systolic pressure had no differences between the groups (p=NS). Conclusion A target-controlled effect site concentration system with ke0 of 1.83 min(-1) based on the time to peak effect from BIS can be able to accurately predict the time course of drug effect in oriental patients, and do not increase the risk of hypotension in clinical practice.