Background and Goal of Study: 
ADMS (Anesthetic Depth Monitor for Sedation, Unimedics Co., Ltd., Seoul, Korea) is a recently introduced anesthetic depth measurement system, which displays the patient’s arousal state as the UNICON Index. We performed pharmacodynamic analysis to compare the performance of the UNICON index to the bispectral index (BIS) as electroencephalographic measures of sevoflurane drug effect during general anesthesia.
Materials and Methods:
We observed 30 adult patients scheduled for laparoscopic gastrectomy with a combined epidural–sevoflurane general anesthesia. During a phase of constant surgical stimulation, end-tidal sevoflurane concentrations were varied between 1 - 4 vol%. This procedure was repeated twice, and end-tidal sevoflurane concentrations, BIS, and UNICON index were recorded simultaneously. Population pharmacodynamic models based on double-sigmoid curves were developed to evaluate the relationship between effect-site sevoflurane concentrations and two electroencephalographic indices. The parameters of the models were estimated by NONMEM VII (Icon Development Solutions, LLC, Ellicott City, USA) by minimizing log likelihood.
Results and Discussion:
A significant (P < 0.001) correlation between BIS and UNICON index was found (r2 =0.60) for the two experimental periods. The individual ke0 (effect site efflux constant), Eplateau (pharmacodynamic plateau between two sigmoid curves) and CE50low (effect-site concentration associated with 50% decrease from Eplateau to Emax) for UNICON (0.29 ± 0.45 min-1, 37.9 ± 3.8, and 3.42 ± 0.96 vol%) did not differ from those of BIS (0.25 ± 0.13 min-1, 38.6 ± 5.0, and 3.87 ± 1.50 vol%). The CE50upper (effect-site concentration associated with 50% decrease from baseline to Eplateau) was significantly smaller (p < 0.001) for UNICON (0.43 ± 0.27 vol%) than for BIS (0.69 ± 0.25 vol%), however, its clinical importance may be limited. 
Conclusion:
Population pharmacodynamic models using double-sigmoid curves adequately described the responses of BIS and UNICON index to sevoflurane anesthesia, and most pharmacodynamic parameters for the BIS and UNICON index were similar.

07 / Comparison between UNICON Index and Bispectral Index using Population Pharmacodynamic Analysis during Sevoflurane Anesthesia