We investigated effect-site median effective concentration (EC₅₀) of propofol for loss of consciousness and effect-site concentration at each anesthetic stage and awakening time to compare the differences by gender or age of patients using Schnider model.

Total 91 patients were allocated into 4 groups: male patients aged 18-34 year (Group 1), male patients aged 35-55 years (Group 2), female patients aged 18-34 years (Group 3) and female patients aged 35-55 years (Group 4). The effect-site EC₅₀ for loss of consciousness was calculated and the effect-site concentration of propofol at each anesthetic stage and the awakening time of each group were recorded.

The effect-site EC₅₀ of propofol for loss of consciousness was 4.53 ± 0.30 µg/ml, 4.60 ± 0.25 µg/ml, 4.13 ± 0.39 µg/ml and 4.47 ± 0.65 µg/ml in group 1, 2, 3, and 4, respectively. The effect-site concentrations in male patients aged 18-34 years were significantly higher than those in female patients. The awakening time of female patients aged 35-55 years was shorter than that of male patients.

There were no significant differences of effect-site EC₅₀ for the loss of consciousness of propofol with target effect-site controlled infusion by Schnider model among the groups. However the effect-site concentrations and the awakening time of propofol by Schnider model showed differences in patients' gender and age.