AimsAn ordinary sigmoid Emax model could not predict overshoot of electroencephalographic approximate entropy (ApEn) during recovery from remifentanil effect in our previous study. The aim of this study was to evaluate the ability of an artificial neural network (ANN) to predict ApEn overshoot and to evaluate the predictive performance of the pharmacokinetic model, and pharmacodynamic models of ANN with respect to data used. MethodsUsing a reduced number of ApEn instances (n = 1581) to make NONMEM modelling feasible and complete ApEn data (n = 24 509), the presence of overshoot was assessed. A total of 1077 measured remifentanil concentrations and ApEn data, and a total of 24 509 predicted concentrations and ApEn data were used in the pharmacodynamic model A and B of ANN, respectively. The testing subset of model B (n = 7352) was used to evaluate the ability of ANN to predict overshoot of ApEn. Mean squared error (MSE) was calculated to evaluate the predictive performance of the ANN models. ResultsWith complete ApEn data, ApEn overshoot was observed in 66.7% of subjects, but only in 37% with a reduced number of ApEn instances. The ANN model B predicted 77.8% of ApEn overshoot. MSE (95% confidence interval) was 57.1 (3.22, 71.03) for the pharmacokinetic model, 0.148 (0.004, 0.007) for model A and 0.0018 (0.0017, 0.0019) for model B. ConclusionsThe reduced ApEn instances interfered with the approximation of true electroencephalographic response. ANN predicted 77.8% of ApEn overshoot. The predictive performance of model B was significantly better than that of model A.

VRT and ART were linearly prolonged with increasing sedation. Visual response may be useful in monitoring conscious sedation.

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Background: Reduction of nasal bone fracture can be performed under general or local anesthesia. The aim of this study was to compare general anesthesia (GA) and monitored anesthetic care (MAC) with dexmedetomidine based on intraoperative vital signs, comfort of patients, surgeons and nurses and the adverse effects after closed reduction of nasal bone fractures. Methods: Sixty patients with American Society of Anesthesiologists physical status I or II were divided into a GA group (n = 30) or MAC group (n = 30). Standard monitorings were applied. In the GA group, general anesthesia was carried out with propofol-sevoflurane-N 2 O. In the MAC group, dexmedetomidine and local anesthetics were administered for sedation and analgesia. Intraoperative vital signs, postoperative pain scores by visual analog scale and postoperative nausea and vomiting (PONV) were compared between the groups. Results: Intraoperatively, systolic blood pressures were significantly higher, and heart rates were lower in the MAC group compared to the GA group. There were no differences between the groups in the patient, nurse and surgeon's satisfaction, postoperative pain scores and incidence of PONV. Conclusions: MAC with dexmedetomidine resulted in comparable satisfaction in the patients, nurses and surgeons compared to general anesthesia. The incidence of postoperative adverse effects and severity of postoperative pain were also similar between the two groups. Therefore, both anesthetic techniques can be used during the reduction of nasal bone fractures based on a patient's preference and medical condition. (Korean J Anesthesiol 2013; 65: 209-214)