RESUMO
BACKGROUND: 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. METHODS: 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. RESULTS: The effect-site EC50 of propofol for loss of consciousness was 4.53 +/- 0.30microgram/ml, 4.60 +/- 0.25microgram/ml, 4.13 +/- 0.39microgram/ ml and 4.47 +/- 0.65microgram/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. CONCLUSIONS: 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.