Quantitative analysis of the effect of fraction ofinspired oxygen on peripheral oxygen saturation inhealthy volunteers

Background@#The international organization for standardization (ISO) 80601-2-61 dictates that the accuracy ofa pulse oximeter should be assessed by a controlled desaturation study. We aimed to characterize the relationshipbetween the fraction of inspired oxygen (FiO2) and peripheral oxygen saturation (SpO2) using a turnover modelby retrospectively analyzing the data obtained from previous controlled desaturation studies. @*Materials and Methods@#Each volunteer was placed in a semi-Fowler’s position and connected to a breathingcircuit to administer the hypoxic gas mixture containing medical air, oxygen, nitrogen, and carbon dioxide.Volunteers were exposed to various levels of induced hypoxia over 70-100% arterial oxygen saturation (SaO2).The study period consisted of two rounds of hypoxia and the volunteers were maintained in room air betweeneach round. FiO2 and SpO2 were recorded continuously during the study period. A population pharmacodynamicanalysis was performed with the NONMEM VII level 4 (ICON Development Solutions, Ellicott City, MD,USA). @*Results@#In total, 2899 SpO2 data points obtained from 20 volunteers were used to determine the pharmacodynamiccharacteristics. The pharmacodynamic parameters were as follows: kout = 0.942 1/min, Imax = 0.802, IC50 =85.3%, γ = 27.3. @*Conclusion@#The changes in SpO2 due to decreases in FiO2 well explained by the turnover model with inhibitoryfunction as a sigmoidal model.

Performance of the MP570T pulse oximeter in volunteers participating in the controlled desaturation study: a comparison of seven probes

Background@#The performance of the pulse oximeter was evaluated based on the ISO 80601-2-61:2011 (E) guidelines. This study aimed to determine whether the various finger probes of the MP570T pulse oximeter (MEK-ICS Co., Ltd., Korea) would provide clinically reliable peripheral oxygen saturation (SpO2) readings over a range of 70100% arterial oxygen saturation (SaO2) during non-motion conditions. @*Methods@#Each volunteer (n = 12) was connected to a breathing circuit for the administration of a hypoxic gas mixture. For frequent blood sampling, an arterial cannula was placed in a radial artery. The following seven pulse oximeter probes were simultaneously attached to each volunteer’s fingers: (1) WA-100 reusable finger probe (MEDNIS Co., Ltd., Korea), (2) MDNA disposable finger probe (MEDNIS Co., Ltd.), (3) IS-1011 disposable finger probe (Insung Medical Co., Ltd., Korea), (4) CJ340NA disposable finger probe (CHUN JI IN Medical Co., Ltd., Korea), (5) NellcorTM OxiMax DS-100A reusable finger probe (Medtronic, USA), (6) NellcorTM OxiMax MAX-N disposable finger probe (Medtronic), and (7) OXI-PRO DA disposable finger probe (Bio-Protech Inc., Korea). @*Results@#A total of 275 SpO2-SaO2 pairs were included in the analysis. The accuracy of the root mean square (Arms) of each probe was 2.83%, 3.98%, 3.75%, 6.84%, 3.43%, 5.17%, and 3.84%, respectively. @*Conclusions@#The MP570T pulse oximeter with WA-100 reusable, MDNA disposable, IS-1011 disposable, NellcorTM OxiMax DS-100A reusable, and OXI-PRO DA disposable finger probes meets an acceptable standard of SpO2 accuracy under non-motion conditions.

Accuracy assessment of a PION TCI pump based on international standards

BACKGROUND: Inaccuracies associated with target-controlled infusion (TCI) delivery systems are attributable to both software and hardware issues, as well as pharmacokinetic variability. However, little is known about the inaccuracy of the syringe pump operating in TCI mode. This study aimed to evaluate the accuracy of the TCI pump based on international standards.METHODS: A test apparatus for accuracy evaluation of a syringe pump (PION TCI®, Bionet Co. Ltd.) was designed to apply the gravimetric method. Pump accuracy was evaluated in terms of deviation defined by the following equation: infusion rate deviation (%) = (Rate(mea) − Rate(est)) / Rate(est) × 100, where Rate(mea) is the infusion rate (ml/h) as measured by the gravimetric system, and Rate(est) is the infusion rate (ml/h) as estimated by the pump. An infusion rate representing TCI mode was determined from previous clinical trial data which evaluated the predictive performance of the pharmacokinetic model. The PION TCI pump used in that clinical trial was used to evaluate accuracy of the syringe pump. The distribution of infusion rates obtained from the clinical trial was calculated, and the median value of the distribution was determined as the representative value.RESULTS: The representative infusion rate representing TCI mode was 31 ml/h, at which the infusion rate deviation was 4.5 ± 1.6%.CONCLUSIONS: The inaccuracy of the syringe pump contributing to TCI system inaccuracy is insignificant.

Derivation of pharmacokinetic equations

A variety of drugs are continuously or intermittently administered to patients during general or regional anesthesia. Pharmacotherapy should also receive priority compared with several treatment modalities including nerve blocks for chronic pain control. Therefore, pharmacology may be fundamental to anesthesia as well as pain medicine. Pharmacokinetic equations quantitatively evaluating drug transfer in the body are essential to understanding pharmacological principles. In mammillary compartmental models, pharmacokinetic equations are easily derived from a few simple principles. The kinetics of drug transfer between compartments is determined initially. Ordinary, linear differential equations are constructed based on the kinetics. The Laplace transforms of these differential equations are used to derive functions for the calculation of drug amounts in the central or effect compartments in the Laplace domain. The inverse Laplace transforms of these functions are used to obtain pharmacokinetic equations in time domain. In this review, a two-compartment mammillary pharmacokinetic model is used to derive pharmacokinetic equations using the aforementioned principles.

Investigation into memory formation according to the level of hypnotic depth using process dissociation

BACKGROUND: Process dissociation procedure has been used to evaluate explicit and implicit memories. Two process-dissociation measurement models are described. METHODS: This prospective study evaluated intraoperative memory formation in Korean patients undergoing elective surgery under general anesthesia and its relation to the depth of hypnotic state. A total of 270 patients enrolled were randomly assigned to three groups based on Bispectral Index (BIS) values in the following ranges: 30 to 40, BIS 40 to 50, and BIS 50 to 60 according to the level of hypnotic depth induced by propofol or sevoflurane during the presentation of wordlists. When the level of hypnotic depth was maintained at the target BIS range, words were played for 15 minutes via headphones to patients. Within 24 hours after the word presentation, memory was assessed using an auditory word stem completion test. The probability of explicit and implicit memory was calculated using original and extended measurement models. Brice interviews were performed within 1 and 24 hours after surgery. RESULTS: A total of 119 patients who did not deviate from the target BIS range were included in the analysis. The 95% confidence interval (CI) of the probability of occurrence of implicit memory evaluated by the original model did not include zero. However, when the extension model was used, 0 was included in the 95% CI. Explicit memory evaluated via Brice interviews did not occur in any group. CONCLUSIONS: When BIS was maintained in the range of 30 to 60 during surgery, no explicit or implicit memory was observed.

Comparison of the clinical performance of the modified Marsh model for propofol between underweight and normal-weight patients with Crohn's disease / 대한마취과학회지

BACKGROUND: The aim of this retrospective study was to compare the clinical performance of the modified Marsh model for propofol between underweight and normal-weight patients with Crohn's disease. METHODS: The medical records of 50 patients who underwent elective surgery for Crohn's disease were reviewed retrospectively. Propofol and remifentanil were administered using target effect-site concentration (Ce)-controlled infusion with the modified Marsh and Minto models. Target Ce values of propofol were adjusted within a range of 2.5–3 µg/ml to maintain a bispectral index (BIS) value of less than 60 during anesthesia maintenance. Dosages of anesthetic agents administered during surgery were compared between underweight and normal-weight patients. The infusion profiles of patients were applied as inputs to calculate the Ce values in the Schnider model. RESULTS: The total midazolam and remifentanil dosages required for underweight patients were higher than those required for normal-weight patients to maintain BIS values at less than 60 within a target propofol Ce range of 2.5–3 µg/ml. Simulation results suggested that the Schnider model may be an appropriate pharmacokinetic model for target-controlled infusion in underweight patients, as the clearance was consistently higher in the Schnider model than the modified Marsh model, particularly in underweight patients. CONCLUSIONS: The modified Marsh model might cause inadvertent propofol underdosing in underweight patients. Future studies are necessary to compare the predictive performance of the modified Marsh and Schnider pharmacokinetic models in underweight patients.

Predictive performance of target controlled infusion of propofol-MCT/LCT using the modified Marsh and Schnider models: a simulation study

BACKGROUND: Only two pharmacokinetic models of propofol are commercially available in the category of target controlled infusion (TCI) pumps: the modified Marsh and Schnider models. Both models were developed using propofol-LCT (long chain triglyceride). Depending on the excipient, the pharmacokinetic properties of fast-acting drugs, such as propofol, vary. Hence, it is necessary to evaluate the predictive performances of both models using propofol-MCT (medium chain triglyceride)/LCT, which is frequently used in clinical practice. METHODS: This was a computer simulation study, using data collected in the previous clinical analysis used to evaluate the predictive performance of a pharmacokinetic model of propofol-MCT/LCT. The infusion profiles for each patient were applied as inputs to both models. Simulations were performed using TCI software, and the simulated plasma concentrations of both models were calculated. RESULTS: In total, 217 plasma samples, obtained from 35 patients, were used to determine the predictive performance. The pooled median (95% CI) biases and inaccuracies were 9.6 (−1.7 to 15.4) and 32.1 (22.6–38.2) respectively, for the modified Marsh model, and −5.9 (−8.9 to −0.7) and 26.3 (21.7–27.8) respectively, for the Schnider model. CONCLUSIONS: Although the pooled bias and inaccuracy of the Schnider models were clinically acceptable (< 10–20% and approximately 20–30%, respectively), the Schnider model consistently produced negatively biased predictions. Conversely, even though the pooled inaccuracy of the modified Marsh model failed to meet this criterion, the value did not deviate significantly from the standard. Therefore, it is reasonable to conclude that both TCI models can be used for propofol-MCT/LCT.

A comparative clinical study on the accuracy and efficacy of Accumate(R) 1100, an infusion pump for patient-controlled analgesia

BACKGROUND: The accuracy and efficacy of patient-controlled analgesia (PCA) devices are crucial because malfunction of the devices may lead to fatal outcomes. The aim of this study is to evaluate the accuracy and efficacy of Accumate(R) 1100, an electronic PCA pump, in comparison with GemStar(R) infusion system. METHODS: Fifty patients scheduled for gastrectomy or colon resection were assigned to the Accumate or GemStar group (n = 25 in each group). Intraoperatively, backflow, siphonage, autoclamp function, and lockout time were tested. Postoperatively, PCA using either Accumate(R) 1100 or GemStar(R) infusion system according to the assigned group was maintained for 48 hours. For PCA, fentanyl 1,500 ug and ketorolac 180 mg in 100 ml were used (demand bolus 1 ml, background infusion 1 ml/h, lockout time 15 minutes). The accuracy of the total infused dose and the level of satisfaction of the patients and users were assessed. The results were compared between the two groups. RESULTS: Although backflow and auto-clamp backflow were less with GemStar(R) infusion system, their extent was negligible in both groups. Siphonage was not different between both pumps. Autoclamp and lockout time worked without abnormalities. The relative error of total infused volume over 48 hours was -0.26 +/- 1.20% and -0.34 +/- 0.48% in the Accumate group and GemStar group, respectively. The Accumate group showed a higher level of satisfaction in terms of the ease of priming (P < 0.05). CONCLUSIONS: The accuracy and clinical efficacy of Accumate(R) 1100 were comparable to those of GemStar(R) infusion system.

Corrigendum: The time-course and RNA interference of TNF-alpha, IL-6, and IL-1beta expression on neuropathic pain induced by L5 spinal nerve transection in rats (Korean J Anesthesiol 2015 April 68(2): 159-169) / 대한마취과학회지

This article was inadvertently omitted Acknowledgments section for grant support.

Clinical and psychological characteristics of propofol abusers in Korea: a survey of propofol abuse in 38, non-healthcare professionals / 대한마취과학회지

BACKGROUND: The aim of this study is to investigate the characteristics of propofol abuse based on the results of a survey analysis of abusers among non-healthcare professionals in Korea. METHODS: Thirty-eight propofol abusers were questioned between October and December 2010, and were enrolled and voluntarily participated in a structured survey consisting of an interview and completing a previously prepared questionnaire. The questionnaire was divided into three distinct parts: part 1 dealt with the history of propofol abuse; part 2 highlighted the problems caused by propofol abuse; and part 3 enquired regarding demographics of abusers. RESULTS: Thirty-one (81.6%) of the 38 interviewees abused propofol for more than one year. During the last 12 months, 34 (89.0%) received propofol at two or three times a week. The minimum and maximum amounts of propofol (median, range) administered each time were 500 (100, 1000) and 2000 (500, 4000) mg, respectively. Stress relief and the maintenance of a sense of well-being were quoted the most important reasons for the first-time administration of propofol and its subsequent abuse, respectively. The majority of abusers (36.0, 97.3%) reported a sense of pleasure or euphoria at the time of their propofol injection. Withdrawal symptoms occurred in five abusers (13.2%). Thirteen (36.1%) reported disruptions in their work life. None of the respondents had previously admitted to and or reported abuse of any other controlled substances. CONCLUSIONS: These results provided reference data for the regulation of propofol in Korea as a controlled substance and may also be of interest to international agencies in other countries.

The time-course and RNA interference of TNF-alpha, IL-6, and IL-1beta expression on neuropathic pain induced by L5 spinal nerve transection in rats / 대한마취과학회지

BACKGROUND: The objective of this study was to investigate the time-course of the expression of TNF-alpha, IL-6, and IL-1beta after L5 spinal nerve transection (SNT), and to determine the effect of small interfering RNA (siRNA) targeting these cytokines on neuropathic pain. METHODS: Rats received control siRNA (CON group, n = 80) or a cocktail of siRNAs targeting these cytokines (COCK group, n = 70). The siRNAs were given via intrathecal catheter 1 d prior to SNT, on the operation day, and 1, 2 and 3 d postoperatively. Behavioral tests and levels of the cytokine mRNAs and proteins as well as glial cell activity were following the L5 SNT. RESULTS: In the CON group, TNF-alpha and IL-1beta mRNA levels increased immediately after SNT and remained high for 6 d, while IL-6 transcripts only began to increase after 12 h. TNF-alpha and IL-1beta mRNA levels in the COCK group were lower than in the CON group at all time points (P < 0.05). In the behavioral tests, allodynia and hyperalgesia were significantly lower in the COCK group from 2 d after SNT (P < 0.05). CONCLUSIONS: The time courses of TNF-alpha, IL-6 and IL-1beta mRNA expression after L5 SNT differ. RNA interference may be a method of reducing the development of mechanical allodynia and hyperalgesia in response to nerve injury.

Modeling of Recovery Profiles in Mentally Disabled and Intact Patients after Sevoflurane Anesthesia; A Pharmacodynamic Analysis

PURPOSE: Mentally disabled patients show different recovery profiles compared to normal patients after general anesthesia. However, the relationship of dose-recovery profiles of mentally disabled patients has never been compared to that of normal patients. MATERIALS AND METHODS: Twenty patients (10 mentally disabled patients and 10 mentally intact patients) scheduled to dental surgery under general anesthesia was recruited. Sevoflurane was administered to maintain anesthesia during dental treatment. At the end of the surgery, sevoflurane was discontinued. End-tidal sevoflurane and recovery of consciousness (ROC) were recorded after sevoflurane discontinuation. The pharmacodynamic relation between the probability of ROC and end-tidal sevoflurane concentration was analyzed using NONMEM software (version VII). RESULTS: End-tidal sevoflurane concentration associated with 50% probability of ROC (C50) and gamma value were lower in the mentally disabled patients (C50=0.37 vol %, gamma=16.5 in mentally intact patients, C50=0.19 vol %, gamma=4.58 in mentally disabled patients). Mentality was a significant covariate of C50 for ROC and gamma value to pharmacodynamic model. CONCLUSION: A sigmoid Emanx model explains the pharmacodynamic relationship between end-tidal sevoflurane concentration and ROC. Mentally disabled patients may recover slower from anesthesia at lower sevoflurane concentration at ROC an compared to normal patients.

Temporal linear mode complexity as a surrogate measure of the anesthetic drug effects during sevoflurane anesthesia / 대한마취과학회지

BACKGROUND: The aims of this study were to compare the stability, correlation with end-tidal sevoflurane, and area below the effect (AUCeffect) vs. time curves of temporal linear mode complexity (TLMC) and approximate entropy (ApEn) during sevoflurane anesthesia. Another study goal was to characterize the time course of the effects of sevoflurane. METHODS: Electroencephalogram (EEG) parame1ter stability was evaluated using the coefficients of variation (CV) of the median baseline (E0), maximal (Emax), and individual median E0 - Emax values. Correlations between sevoflurane concentration and EEG parameters were tested. AUCeffect vs. time curves of TLMC and ApEn were calculated to quantitate any decrease in central nervous system activities. A sigmoid Emax model was used for pharmacodynamic modeling. RESULTS: TLMC and ApEn demonstrated CVs of 8.36 and 7.35 (for E0) and 19.61 and 13.45 (Emax), respectively. The CVs of the individual median E0 - Emax values were 65.16 for TLMC and 59.97 for ApEn. The Spearman correlation coefficient was -0.3103 for TLMC and -0.3410 for ApEn (P < 0.001 for both parameters). The median AUCeffect value was 338.9 for TLMC and 246.5 for ApEn (P = 0.457). The final pharmacodynamic parameters estimated by sigmoid Emax models were described as follows; E0: 0.614, 0.617, Emax: 0.334, 0.287, Ce50: 5.48, 5.07 vol%, gamma: 1.88, 2.01, ke0: 0.306, 0.236 min (TLMC, ApEn). CONCLUSIONS: TLMC is comparable to ApEn according to the univariate EEG descriptors of the effects of sevoflurane. A sigmoid Emax model well described the pharmacodynamics of sevoflurane for TLMC and ApEn.

The comparison of predictive performance in bispectral index prediction during target effect-site controlled infusion of propofol using different blood effect-site equilibration rate constants in the same pharmacokinetic model / 대한마취과학회지

BACKGROUND: Blood-brain equilibration rate constant (k(e0)) is derived from either pharmacokinetic and pharmacodynamic modeling (k(e0_model)) or a model-independent observed time to peak effect (k(e0_tpeak)). Performance in bispectral index (BIS) prediction was compared between k(e0_model) and k(e0_tpeak) for microemulsion or long chain triglyceride (LCT) propofol. METHODS: Time to peak effect (t(peak), time to a maximally reduced BIS value) of microemulsion propofol after an intravenous bolus (1 mg/kg) was measured in 100 patients (group A(micro)). An observed t(peak) of 1.6 min for LCT propofol was obtained from an earlier study. Another 40 patients received a target controlled infusions of microemulsion propofol (k(e0_model) = 0.187/min, group B(micro) = 20) or LCT propofol (k(e0_model) = 0.26/min, group B(LCT) = 20) and remifentanil. The k(e0_tpeak)'s in group B(micro) and B(LCT) were calculated using the observed t(peak) value obtained from group A(micro) and 1.6 min, respectively. Effect-site concentrations of propofol were recalculated using the amounts of propofol infused over time and k(e0_tpeak)'s. Predicted BIS values calculated by sigmoid Emax equations with k(e0_model) and k(e0_tpeak) were compared with observed BIS values during induction and emergence for both formulations of propofol. RESULTS: Observed t(peak) of microemulsion propofol was 1.68 min. The median performance errors of BIS in group B(micro) were -1.83% (-24.8 to 18.9, k(e0_model)) and -2.42% (-26.1 to 36.2, k(e0_tpeak)), while 8.01% (-20.5 to 30.1, k(e0_model)) and 7.37% (-27.0 to 49.1, k(e0_tpeak)) in group B(LCT). The median absolute performance errors of BIS in group B(micro) were 11.87% (2.2-31.1k(e0_model)) and 14.38% (-0.6 to 44.6, k(e0_tpeak)), while 17.31% (5.54-36.0, k(e0_model)) and 18.28% (-0.1 to 56.0, k(e0_tpeak)) in group B(LCT). CONCLUSIONS: The k(e0_model) showed better performance in BIS prediction than the k(e0_tpeak).

The optimal concentration of siRNA for gene silencing in primary cultured astrocytes and microglial cells of rats / 대한마취과학회지

BACKGROUND: Small interfering RNAs (siRNAs) have been used to knockdown specific gene expression in various cells. Astrocytes and microglial cells play a key role in fundamental central nervous system functions and in chronic neuroinflammation. The aims of this study were to determine the optimal concentration of siRNA demonstrating efficient transfection and inhibition of gene expression via RNA interference (RNAi) and lower cytotoxicity, in primary cultured astrocytes and microglial cells of rats. METHODS: Astrocytes and microglial cells were isolated from the cerebral cortices of 2-day-old rats. Both the cells were transfected using transfection reagent (Lipofectaminetrade mark 2000), and fluorescein-labeled double-stranded RNA (dsRNA) or siRNA targeting green fluorescent protein. Transfection efficiency and cytotoxicity of dsRNA, and the degrees of RNAi induced by siRNA in these cells, were evaluated at various concentrations of RNA. RESULTS: Transfection efficiencies of dsRNA in both astrocytes and microglial cells were significantly higher (P < 0.05) at the concentrations of 20, 40, and 80 nM than at the concentrations of 0, 5, and 10 nM. There were no significant cytotoxicities within the applied concentrations of dsRNA (0-80 nM). The degrees of RNAi induced by siRNA were significantly higher (P < 0.05) at the concentrations of 5, 10, 20, 40, 80 nM, and 20, 40, 80 nM in astrocytes and microglial cells, respectively, compared with the control (0 nM). CONCLUSIONS: The siRNA concentration of 20 nM may be appropriate to induce RNAi in both astrocytes and microglial cells, while demonstrating low cytotoxicity, high transfection efficiency, and effective RNAi.

Ultrasound-guided evaluation of the bifurcation of the femoral artery and vein in pediatric patients / 대한마취과학회지

BACKGROUND: The femoral arteries (FA) and femoral veins (FV) are useful access sites for diagnostic and interventional procedures. In adults, the usual puncture sites are 1-3 cm distal from the inguinal crease. In children, however, the optimal puncture site vessels are not known. The aim of our study was to assess the number of branches and bifurcation sites of the femoral vessels in children by using ultrasonography. METHODS: Color Doppler ultrasonography was used to determine bifurcation sites of the FA and FV, relative to the inguinal crease, in 48 children (median age, 4 yr; median weight, 18.7 kg) with American Society of Anesthesiologists (ASA) Physical Status (PS) score 1-2 and who were scheduled for general anesthesia. RESULTS: The numbers of FAs and FVs at the inguinal crease were 1.83 +/- 0.39 and 1.08 +/- 0.29, respectively, in infants, and 1.83 +/- 0.58 and 1.0 +/- 0.0, respectively, in 10-year-old children. The bifurcation site of the FA in infants and those aged 10 years was 0.78 +/- 0.30 cm and 1.47 +/- 0.27 cm proximal to the inguinal crease, respectively (P < 0.05), whereas the bifurcation site of the FV in these two age groups was -0.96 +/- 0.27 cm and -2.29 +/- 1.09 cm distal to the inguinal crease, respectively (P < 0.05). CONCLUSIONS: In children, the FA frequently bifurcates proximal to the inguinal crease, whereas the FV bifurcates distal to the inguinal crease. However, there are anatomical differences among age groups, so care should be taken to avoid complications during femoral vessel cannulation.

Population Pharmacokinetic and Pharmacodynamic Models of Propofol in Healthy Volunteers using NONMEM and Machine Learning Methods / 대한의료정보학회지

OBJECTIVES: The primary objective of this study is to compare model performance of machine learning methods with that of a previous study in which a nonlinear mixed effects model was created using NONMEM(R) for the pharmacokinetic and pharmacodynamic data for propofol. The secondary objective was to evaluate if a pharmacodynamic model describing the relationship between the dose of propofol and bispectral index (BIS) outperform that describing the relationship between a pharmacokinetic model derived-predicted concentrations of propofol and BIS. METHODS: Data were collected during a study involving the infusion of propofol into healthy volunteers. Pharmacokinetic and pharmacodynamic models were constructed using artificial neural networks (ANNs), support vector machines (SVMs), and multi-method ensembles and were compared with the nonlinear mixed effects method as implemented by NONMEM(R). Model performance was assessed by goodness-of-fit statistics, paired t-tests between predicted and observed values for each model and scatterplots. RESULTS: In pharmacokinetic analysis, ensemble I, the mean of ANN and NONMEM(R) predictions, achieved minimal error and the highest correlation coefficient. SVM produced the highest error and the lowest correlation coefficient. In pharmacodynamic analysis, ANN exhibited the best performance. An ANNModel describing the relationship between the dose of propofol and BIS was not inferior to an ANN model describing the relationship between predicted concentrations of propofol derived from an ANN pharmacokinetic model and BIS. CONCLUSIONS: In pharmacokinetic analysis, ensemble combined with ANN achieved slightly better performance than NONMEM(R). The relationship between the dose of propofol and BIS can be predicted without considering pharmacokinetics of propofol.

Approximate entropy as the measurement of the electroencephalographic effect during sevoflurane induction / 대한마취과학회지

BACKGROUND: The processed electroencephalograms are useful surrogate measures of quantification of volatile anesthetics effect. We hypothesized that there is a certain relationship between the end-tidal concentration of sevoflurane and approximate entropy (ApEn). The aim of this study was to investigate the effect of sevoflurane on ApEn during induction. METHODS: Fourteen patients were enrolled. With recording of the electroencephalogram at the F3, F4, P3, and P4 montages, anesthesia was induced by increasing the vapor setting of sevoflurane by 1 vol% up to 8 vol% via a facemask. When the end-tidal concentration of sevoflurane did not show any further change, we increased vapor setting of sevoflurane by 1 vol%. When the end-tidal concentration of sevoflurane did not show any further change with 8 vol% of sevoflurane vapor setting, measurement of electroencephalogram was finished. The relation between end-tidal sevoflurane concentration and ApEn was tested by Spearman correlation. RESULTS: ApEn showed a significant correlation (R = -0.7551, P < 0.0001) with end-tidal sevoflurane concentration. The final pharmacodynamic parameters estimated by a sigmoid E(max) model were described as follows: E(0) = 0.91, E(max) = 0.28, C(e50) = 1.36 vol%, gamma = 1.27, kappa(e0) = 0.67 min(-1). CONCLUSIONS: Sevoflurane induction with gradual increase of end-tidal sevoflurane concentration increases the amount of regularity in approximate entropy.

A Clinical Study to Evaluate the Safety and Efficacy of a Patient-controlled Analgesia Pump in Post-surgical Patients / 대한마취과학회지

BACKGROUND: The disposable patient-controlled analgesia (PCA) devices are convenient for portability and management. An ideal PCA can be developed as an electronic device with various functions of safety and control. Recently, Accumate 1000(R) was developed as an electronic pump in Korea, and has passed the relevant laboratory criteria of safety and efficacy. We conducted a clinical study on the safety and efficacy when the device is applied to patients. METHODS: Fentanyl 1,500microgram, ketorolac 180 mg, and ondansetron 8 mg were used for PCA. Continuous infusion rate, bolus dose, and lockout time were set at 1 ml/h, 1 ml, and 15 min, respectively. Fifty patients were monitored for 48 h. The safety of Accumate 1000(R) was evaluated by backflow and siphonage, auto-clamp function, and lockout time intraoperatively. The efficacy was evaluated by the accuracy of bolus and total infused dose, and the satisfaction rates of patients and users. RESULTS: Backflow and siphonage did not occur, and the auto-clamp function was excellent. There was no bolus infusion during lockout time, and the bolus dose was infused accurately after lockout time. For the accuracy of the total infused dose, the mean and median value of performance error between the infused and target doses were -0.55%, and -0.29%, respectively. Noise, button sense, and convenience of cable were rated as satisfactory by 90%, 78%, and 84%, of patients respectively. CONCLUSIONS: The safety and efficacy of Accumate 1000(R) were established by clinical trial. We can provide patients with the more precise and optimal analgesia. The history of drug infusion can be used as research data.

Chlorhexidine Anaphylaxis after Urethral Catheterization during Anesthesia : A case report / 대한마취과학회지

Chlorhexidine is a widely used antiseptic and disinfectant that has eliminating effects on gram-positive bacteria, gram-negative bacteria, some mycobacteria, candida albicans, and some viruses. There have been a few reports regarding severe adverse reactions associated with chlorhexidine. But, there was no report about the anaphylactic shock due to chlorhexidine during anesthesia in Korea. We report a severe anaphylaxis reaction after the use of chlorhexidine jelly for the urethral catheterization, presenting the positive skin test for chlorhexidine. This case shows that the 'innocent' products such as urethral lubricants may elicit serious life-threatening reactions.