The Experts below are selected from a list of 417387 Experts worldwide ranked by ideXlab platform
Steven L Shafer - One of the best experts on this subject based on the ideXlab platform.
-
spectral entropy as an electroencephalographic measure of anesthetic Drug Effect a comparison with bispectral index and processed midlatency auditory evoked response
Anesthesiology, 2004Co-Authors: Ann Vanluchene, Steven L Shafer, Eric Mortier, Hugo Vereecke, Olivier Thas, Michel StruysAbstract:Background: The authors compared the behavior of two calculations of electroencephalographic spectral entropy, state entropy (SE) and response entropy (RE), with the A-Line(R) ARX index (AM) and the Bispectral index (BIS) and as measures of anesthetic Drug Effect. They compared the measures for baseline variability, burst suppression, and prediction probability. They also developed pharmacodynamic models relating SE, RE, AM, and BIS to the calculated propofol Effect-site concentration (Ce-prop). Methods: With institutional review board approval, the authors studied 10 patients. All patients received 50 mg/min propofol until either burst suppression greater than 80% or mean arterial pressure less than 50 mmHg was observed. SE, RE, AAI and BIS were continuously recorded. Ce-prop was calculated from the propofol infusion profile. Baseline variability, prediction of burst suppression, prediction probability, and Spearman rank correlation were calculated for SE, RE, AAI, and BIS. The relations between Ce-prop and the electroencephalographic measures of Drug Effect were estimated using nonlinear mixed Effect modeling. Results: Baseline variability was lowest when using SE and RE. Burst suppression was most accurately detected by spectral entropy. Prediction probability and individualized Spearman rank correlation were highest for BIS and lowest for SE. Nonlinear mixed Effect modeling generated reasonable models relating all four measures to Ce-prop. Conclusions: Compared with BIS and AM, both SE and RE seem to be useful electroenceplialographic measures of anesthetic Drug Effect, with low baseline variability and accurate burst suppression prediction. The ability of the measures to predict Ce-prop was best for BIS.
-
using the time of maximum Effect site concentration to combine pharmacokinetics and pharmacodynamics
Anesthesiology, 2003Co-Authors: Charles F Minto, Keith M. Gregg, Thomas W Schnider, Thomas K Henthorn, Steven L ShaferAbstract:BackgroundTo simulate the time course of Drug Effect, it is sometimes necessary to combine the pharmacodynamic parameters from an integrated pharmacodynamic–pharmacodynamic study (e.g., volumes, clearances, ke0 [the Effect site equilibration rate constant], C50 [the steady state plasma concentration
-
Comparison of plasma compartment versus two methods for Effect compartment-controlled target-controlled infusion for propofol
Anesthesiology, 2000Co-Authors: Michel Struys, Steven L Shafer, Tom De Smet, Birgit Depoorter, Linda Versichelen, Eric Mortier, Frank J E Dumortier, Georges RollyAbstract:Background: Target-controlled infusion (TCI) systems can control the concentration in the plasma or at the site of Drug Effect. A TCI system that targets the Effect site should be able to accurately predict the time course of Drug Effect. The authors tested this by comparing the performance of three control algorithms: plasma-control TCI versus two algorithms for Effect-site control TCI, Methods: One-hundred twenty healthy women patients received propofol via TCI for 12-min at a target concentration of 5.4 mu g/ml, In all three groups, the plasma concentrations mere computed using pharmacokinetics previously reported. In group I, the TCI device controlled the plasma concentration. In groups II and III, the TCI device controlled the Effect-site concentration. In group II, the Effect site was computed using a half-life for plasma Effect-site equilibration (t(1/2) k(eo)) of 3.5 min. In group m, plasma Effect-site equilibration rate constant (k(eo)) was computed to yield a time to peak Effect of 1.6 min after bolus injection, yielding a t(1/2), k(eo) of 34 s, the time course of propofol was measured using the bispectral index, Blood pressure, ventilation, and time of loss of consciousness were measured. Results The time course of propofol Drug Effect, as measured by the bispectral index, was best predicted in group III. Targeting the Effect-site concentration shortened the time to loss of consciousness compared with the targeting plasma concentration without causing hypotension. The incidence of apnea was less in group III than in group II. Conclusion: Effect compartment-controlled TCI can be safely applied in clinical practice. A biophase model combining the Marsh kinetics and a time to peak Effect of 1.6 min accurately predicted the time course of propofol Drug Effect.
-
a comparison of spectral edge delta power and bispectral index as eeg measures of alfentanil propofol and midazolam Drug Effect
Clinical Pharmacology & Therapeutics, 1997Co-Authors: Valerie Billard, Pedro L. Gambus, Nassib Chamoun, Donald R Stanski, Steven L ShaferAbstract:Background The Effects of anesthetic Drugs on electroencephalograms (EEG) have been studied to develop the EEG as a measure of anesthetic depth. Bispectral analysis is a new quantitative technique that measures the consistency of the phase and power relationships and returns a single measure, the bispectral index. The purpose of this study was to compare the performance of the bispectral index, version 1.1, with other spectral analysis EEG measures of Drug Effect for three commonly used anesthetic Drugs. Methods The EEG waveforms from 31 adults receiving infusions of alfentanil, propofol, or midazolam were analyzed. The time course of spectral edge (Se95), relative power in delta band, and bispectral index were related to the estimated Effect-site concentration with use of a sigmoidal Emax model to estimate the potency (IC50) and the plasma Effect-site equilibration rate constant (ke0) for each measure. The performance of the fitting was assessed by the coefficient of correlation between predicted and observed Effect. Results Alfentanil induced a high-amplitude low-frequency EEG response. Propofol induced a biphasic response. At low concentrations, both frequency and amplitude increased. When the concentration increased, the EEG slowed and the amplitude decreased. High concentration produced burst suppression. Midazolam increased EEG frequency and amplitude. Bispectral index, SE95, and delta power yield similar estimates of IC50 and ke0. Except for alfentanil, the performance of the modeling with the bispectral index was as good that with SE95 or delta power. Conclusion Bispectral analysis can be used as a measure of the EEG Effects of anesthetic Drugs. Clinical Pharmacology & Therapeutics (1997) 61, 45–58; doi:
-
Does the EEG Measure Therapeutic Opioid Drug Effect
Control and Automation in Anaesthesia, 1995Co-Authors: V. Billard, Steven L ShaferAbstract:In this chapter we discuss the extent to which the EEG reflects therapeutic opioid Drug Effect. For the hypnotics, the EEG has been used to control the depth of anesthesia via closed-loop administration. These systems will be discussed in the chapters by Professors Schwilden [1, 2] (median frequency) and Kenny (auditory-evoked potentials). That computerized systems are able to satisfactorily administer hypnotics based on direct feedback from EEG-derived measures suggests that the EEG is, in fact, a very reasonable measure of hypnotic Drug Effect. Thus, we will focus here on the EEG as a measure of the therapeutic Effect of opioids.
Michel Struys - One of the best experts on this subject based on the ideXlab platform.
-
Influence of an "Electroencephalogram-Based" Monitor Choice on the Delay Between the Predicted Propofol Effect-Site Concentration and the Measured Drug Effect.
Anesthesia and analgesia, 2020Co-Authors: Marko M. Sahinovic, Johannes P Van Den Berg, Pieter Colin, Pedro L. Gambus, Erik W. Jensen, Merce Agusti, Teresa Ferreiro, Michel StruysAbstract:BACKGROUND Clinicians can optimize propofol titration by using 2 sources of pharmacodynamic (PD) information: the predicted Effect-site concentration for propofol (Ceprop) and the electroencephalographically (EEG) measured Drug Effect. Relation between these sources should be time independent, that is, perfectly synchronized. In reality, various issues corrupt time independency, leading to asynchrony or, in other words, hysteresis. This asynchrony can lead to conflicting information, making Effective Drug dosing challenging. In this study, we tried to quantify and minimize the hysteresis between the Ceprop (calculated using the Schnider model for propofol) and EEG measured Drug Effect, using nonlinear mixed-Effects modeling (NONMEM). Further, we measured the influence of EEG-based monitor choice, namely Bispectral index (BIS) versus qCON index (qCON) monitor, on propofol PD hysteresis. METHODS We analyzed the PD data from 165 patients undergoing propofol-remifentanil anesthesia for outpatient surgery. Drugs were administered using target-controlled infusion (TCI) pumps. Pumps were programmed with Schnider model for propofol and Minto model for remifentanil. We constructed 2 PD models (direct models) relating the Schnider Ceprop to the measured BIS and qCON monitor values. We quantified the models' misspecification due to hysteresis, on an individual level, using the root mean squared errors (RMSEs). Subsequently, we optimized the PD models' predictions by adding a lag term to both models (lag-time PD models) and quantified the optimization using the RMSE. RESULTS There is a counterclockwise hysteresis between Ceprop and BIS/qCON values. Not accounting for this hysteresis results in a direct PD model with an Effect-site concentration which produces 50% of the maximal Drug Effect (Ce50) of 6.24 and 8.62 µg/mL and RMSE (median and interquartile range [IQR]) of 9.38 (7.92-11.23) and 8.41 (7.04-10.2) for BIS and qCON, respectively. Adding a modeled lag factor of 49 seconds to the BIS model and 53 seconds to the qCON model improved both models' prediction, resulting in similar Ce50 (3.66 and 3.62 µg/mL for BIS and qCON) and lower RMSE (median (IQR) of 7.87 (6.49-9.90) and 6.56 (5.28-8.57) for BIS and qCON. CONCLUSIONS There is a significant "Ceprop versus EEG measured Drug Effect" hysteresis. Not accounting for it leads to conflicting PD information and false high Ce50 for propofol in both monitors. Adding a lag term improved the PD model performance, improved the "pump-monitor" synchrony, and made the estimates of Ce50 for propofol more realistic and less monitor dependent.
-
spectral entropy as an electroencephalographic measure of anesthetic Drug Effect a comparison with bispectral index and processed midlatency auditory evoked response
Anesthesiology, 2004Co-Authors: Ann Vanluchene, Steven L Shafer, Eric Mortier, Hugo Vereecke, Olivier Thas, Michel StruysAbstract:Background: The authors compared the behavior of two calculations of electroencephalographic spectral entropy, state entropy (SE) and response entropy (RE), with the A-Line(R) ARX index (AM) and the Bispectral index (BIS) and as measures of anesthetic Drug Effect. They compared the measures for baseline variability, burst suppression, and prediction probability. They also developed pharmacodynamic models relating SE, RE, AM, and BIS to the calculated propofol Effect-site concentration (Ce-prop). Methods: With institutional review board approval, the authors studied 10 patients. All patients received 50 mg/min propofol until either burst suppression greater than 80% or mean arterial pressure less than 50 mmHg was observed. SE, RE, AAI and BIS were continuously recorded. Ce-prop was calculated from the propofol infusion profile. Baseline variability, prediction of burst suppression, prediction probability, and Spearman rank correlation were calculated for SE, RE, AAI, and BIS. The relations between Ce-prop and the electroencephalographic measures of Drug Effect were estimated using nonlinear mixed Effect modeling. Results: Baseline variability was lowest when using SE and RE. Burst suppression was most accurately detected by spectral entropy. Prediction probability and individualized Spearman rank correlation were highest for BIS and lowest for SE. Nonlinear mixed Effect modeling generated reasonable models relating all four measures to Ce-prop. Conclusions: Compared with BIS and AM, both SE and RE seem to be useful electroenceplialographic measures of anesthetic Drug Effect, with low baseline variability and accurate burst suppression prediction. The ability of the measures to predict Ce-prop was best for BIS.
-
Comparison of plasma compartment versus two methods for Effect compartment-controlled target-controlled infusion for propofol
Anesthesiology, 2000Co-Authors: Michel Struys, Steven L Shafer, Tom De Smet, Birgit Depoorter, Linda Versichelen, Eric Mortier, Frank J E Dumortier, Georges RollyAbstract:Background: Target-controlled infusion (TCI) systems can control the concentration in the plasma or at the site of Drug Effect. A TCI system that targets the Effect site should be able to accurately predict the time course of Drug Effect. The authors tested this by comparing the performance of three control algorithms: plasma-control TCI versus two algorithms for Effect-site control TCI, Methods: One-hundred twenty healthy women patients received propofol via TCI for 12-min at a target concentration of 5.4 mu g/ml, In all three groups, the plasma concentrations mere computed using pharmacokinetics previously reported. In group I, the TCI device controlled the plasma concentration. In groups II and III, the TCI device controlled the Effect-site concentration. In group II, the Effect site was computed using a half-life for plasma Effect-site equilibration (t(1/2) k(eo)) of 3.5 min. In group m, plasma Effect-site equilibration rate constant (k(eo)) was computed to yield a time to peak Effect of 1.6 min after bolus injection, yielding a t(1/2), k(eo) of 34 s, the time course of propofol was measured using the bispectral index, Blood pressure, ventilation, and time of loss of consciousness were measured. Results The time course of propofol Drug Effect, as measured by the bispectral index, was best predicted in group III. Targeting the Effect-site concentration shortened the time to loss of consciousness compared with the targeting plasma concentration without causing hypotension. The incidence of apnea was less in group III than in group II. Conclusion: Effect compartment-controlled TCI can be safely applied in clinical practice. A biophase model combining the Marsh kinetics and a time to peak Effect of 1.6 min accurately predicted the time course of propofol Drug Effect.
-
Comparison of spontaneous frontal EMG, EEG power spectrum and bispectral index to monitor propofol Drug Effect and emergence
Acta anaesthesiologica Scandinavica, 1998Co-Authors: Michel Struys, Linda Versichelen, Eric Mortier, D Ryckaert, J C De Mey, C. De Deyne, Georges RollyAbstract:Background: The aim of this study was to investigate the accuracy of frontal spontaneous electromyography (SEMG) and EEG spectral edge frequency (SEF 95%), median frequency (MF), relative delta power (RDELTA) and bispectral index (BIS) in monitoring loss of and return of consciousness and hypnotic Drug Effect during propofol administration at different calculated plasma target concentrations. Methods: Propofol was administered by using a target-controlled infusion at different propofol steady-state concentrations. All variables were measured simultaneously at specific calculated concentrations and endpoints. Results: Loss of consciousness was accurately monitored by BIS, SEMG and SEF 95%, and propofol Drug Effect by BIS only. Return of consciousness was predicted by BIS, MF and SEF 95%. Due to the biphasic EEG pattern of propofol and the lack of reproducible data at specific propofol concentrations, the clinical usefulness of SEF 95%, MF and RDELTA was very limited. SEMG was useful to detect loss and return of consciousness, but without predictive value. Conclusions: The BIS might be an accurate measure to monitor depth of anaesthesia and hypnotic Drug Effect. Other neurophysiologic measures have limited value to monitor depth of anaesthesia and hypnotic Drug Effect.
Georges Rolly - One of the best experts on this subject based on the ideXlab platform.
-
Comparison of plasma compartment versus two methods for Effect compartment-controlled target-controlled infusion for propofol
Anesthesiology, 2000Co-Authors: Michel Struys, Steven L Shafer, Tom De Smet, Birgit Depoorter, Linda Versichelen, Eric Mortier, Frank J E Dumortier, Georges RollyAbstract:Background: Target-controlled infusion (TCI) systems can control the concentration in the plasma or at the site of Drug Effect. A TCI system that targets the Effect site should be able to accurately predict the time course of Drug Effect. The authors tested this by comparing the performance of three control algorithms: plasma-control TCI versus two algorithms for Effect-site control TCI, Methods: One-hundred twenty healthy women patients received propofol via TCI for 12-min at a target concentration of 5.4 mu g/ml, In all three groups, the plasma concentrations mere computed using pharmacokinetics previously reported. In group I, the TCI device controlled the plasma concentration. In groups II and III, the TCI device controlled the Effect-site concentration. In group II, the Effect site was computed using a half-life for plasma Effect-site equilibration (t(1/2) k(eo)) of 3.5 min. In group m, plasma Effect-site equilibration rate constant (k(eo)) was computed to yield a time to peak Effect of 1.6 min after bolus injection, yielding a t(1/2), k(eo) of 34 s, the time course of propofol was measured using the bispectral index, Blood pressure, ventilation, and time of loss of consciousness were measured. Results The time course of propofol Drug Effect, as measured by the bispectral index, was best predicted in group III. Targeting the Effect-site concentration shortened the time to loss of consciousness compared with the targeting plasma concentration without causing hypotension. The incidence of apnea was less in group III than in group II. Conclusion: Effect compartment-controlled TCI can be safely applied in clinical practice. A biophase model combining the Marsh kinetics and a time to peak Effect of 1.6 min accurately predicted the time course of propofol Drug Effect.
-
Comparison of spontaneous frontal EMG, EEG power spectrum and bispectral index to monitor propofol Drug Effect and emergence
Acta anaesthesiologica Scandinavica, 1998Co-Authors: Michel Struys, Linda Versichelen, Eric Mortier, D Ryckaert, J C De Mey, C. De Deyne, Georges RollyAbstract:Background: The aim of this study was to investigate the accuracy of frontal spontaneous electromyography (SEMG) and EEG spectral edge frequency (SEF 95%), median frequency (MF), relative delta power (RDELTA) and bispectral index (BIS) in monitoring loss of and return of consciousness and hypnotic Drug Effect during propofol administration at different calculated plasma target concentrations. Methods: Propofol was administered by using a target-controlled infusion at different propofol steady-state concentrations. All variables were measured simultaneously at specific calculated concentrations and endpoints. Results: Loss of consciousness was accurately monitored by BIS, SEMG and SEF 95%, and propofol Drug Effect by BIS only. Return of consciousness was predicted by BIS, MF and SEF 95%. Due to the biphasic EEG pattern of propofol and the lack of reproducible data at specific propofol concentrations, the clinical usefulness of SEF 95%, MF and RDELTA was very limited. SEMG was useful to detect loss and return of consciousness, but without predictive value. Conclusions: The BIS might be an accurate measure to monitor depth of anaesthesia and hypnotic Drug Effect. Other neurophysiologic measures have limited value to monitor depth of anaesthesia and hypnotic Drug Effect.
R. Segarra - One of the best experts on this subject based on the ideXlab platform.
-
Therapeutic Drug Monitoring of Second-Generation Antipsychotics for the Estimation of Early Drug Effect in First-Episode Psychosis: A Cross-sectional Assessment.
Therapeutic drug monitoring, 2018Co-Authors: Mariana Bustillo, Arantzazu Zabala, I. Querejeta, Jaione I. Carton, Oiane Mentxaka, Ana González-pinto, Sainza García, J. Javier Meana, J Ignacio Eguiluz, R. SegarraAbstract:BACKGROUND Studies on therapeutic Drug monitoring (TDM) of second-generation antipsychotics (SGAs) have provided conflicting results regarding the association between dose, plasma concentrations, and Drug Effect and have focused rather on analyzing how individual Drugs work. No study has attempted to process data from different SGAs globally to offer a panoramic view of the utility of TDM in clinical practice, and data on patients with first-episode psychosis (FEP) are lacking. This study aimed to assess the relationship between dose, plasma concentrations, and Drug Effect in a sample of patients with FEP, regardless of the SGA prescribed. METHODS Data from 64 compliant patients treated with the same SGA during a 2-month follow-up were recorded. Clinical symptoms were assessed using the Positive and Negative Symptoms Scale and the Montgomery-Asberg Depression Rating Scale. Adverse Effects were rated using the Udvalg fur Kliniske Undersogelser scale. SGA doses were standardized to chlorpromazine equivalents, and patients were classified into 3 different ranges according to their plasma concentrations (subtherapeutic, therapeutic, and supratherapeutic). RESULTS Plasma concentration ranges were proportionally related to dose. Patients with supratherapeutic plasma concentrations were treated with doses significantly higher than those with subtherapeutic concentrations. Dose and plasma concentrations were not associated with early Drug Effect. CONCLUSIONS TDM seems unable to accurately estimate the early Effects of SGAs in FEP. Ours is the first study to categorize plasma concentrations of SGAs into ranges for joint processing of data from a larger number of patients.
-
A Pilot Study of the Usefulness of a Single Olanzapine Plasma Concentration as an Indicator of Early Drug Effect in a Small Sample of First-Episode Psychosis Patients.
Journal of clinical psychopharmacology, 2017Co-Authors: Arantzazu Zabala, Mariana Bustillo, I. Querejeta, Oiane Mentxaka, Ana González-pinto, J. Javier Meana, Marta Alonso, Amaia Ugarte, Miguel Gutiérrez, R. SegarraAbstract:PURPOSE/BACKGROUND Studies analyzing concentration-Effect relationships in second-generation antipsychotics have reported contradictory results in chronic schizophrenia. No data are available for the early stages of the disease. The present study aims to evaluate the association between a single olanzapine plasma concentration, clinical response, and severity of adverse Effects in first-episode psychosis (FEP); to test the utility of various plasma breakpoints as markers of early response to treatment; and to identify variables affecting olanzapine concentrations. METHODS Data from 23 compliant FEP patients receiving olanzapine monotherapy (5-30 mg/d) were evaluated 2 months after beginning treatment. Clinical symptoms were assessed using the Positive and Negative Syndrome Scale and the Montgomery-Asberg Depression Rating Scale. Adverse Effects were rated using the Udvalg for Kliniske Undersogelser scale. Plasma samples were drawn at 11 (SD, 1) hours after dosing and analyzed with high-performance liquid chromatography/tandem mass spectrometry. FINDINGS Consistent with findings on chronic disease, dose, age, sex, weight, and cigarettes/day accounted for some of the variability in olanzapine concentrations. While no relationship was found between olanzapine concentrations and adverse Effects or improvement of depressive symptoms, response of psychotic symptoms was associated with concentrations between 22.56 and 77.92 ng/mL. Plasma breakpoints did not show sufficiently high specificity, resulting in a large number of false-positive results. IMPLICATIONS Although olanzapine concentrations do not seem to be reliable indicators of early Drug Effect in FEP, they may still prove useful for detecting noncompliance, as well as pharmacokinetically relevant comorbidities or genetic particularities in Drug metabolism.
Eric Mortier - One of the best experts on this subject based on the ideXlab platform.
-
spectral entropy as an electroencephalographic measure of anesthetic Drug Effect a comparison with bispectral index and processed midlatency auditory evoked response
Anesthesiology, 2004Co-Authors: Ann Vanluchene, Steven L Shafer, Eric Mortier, Hugo Vereecke, Olivier Thas, Michel StruysAbstract:Background: The authors compared the behavior of two calculations of electroencephalographic spectral entropy, state entropy (SE) and response entropy (RE), with the A-Line(R) ARX index (AM) and the Bispectral index (BIS) and as measures of anesthetic Drug Effect. They compared the measures for baseline variability, burst suppression, and prediction probability. They also developed pharmacodynamic models relating SE, RE, AM, and BIS to the calculated propofol Effect-site concentration (Ce-prop). Methods: With institutional review board approval, the authors studied 10 patients. All patients received 50 mg/min propofol until either burst suppression greater than 80% or mean arterial pressure less than 50 mmHg was observed. SE, RE, AAI and BIS were continuously recorded. Ce-prop was calculated from the propofol infusion profile. Baseline variability, prediction of burst suppression, prediction probability, and Spearman rank correlation were calculated for SE, RE, AAI, and BIS. The relations between Ce-prop and the electroencephalographic measures of Drug Effect were estimated using nonlinear mixed Effect modeling. Results: Baseline variability was lowest when using SE and RE. Burst suppression was most accurately detected by spectral entropy. Prediction probability and individualized Spearman rank correlation were highest for BIS and lowest for SE. Nonlinear mixed Effect modeling generated reasonable models relating all four measures to Ce-prop. Conclusions: Compared with BIS and AM, both SE and RE seem to be useful electroenceplialographic measures of anesthetic Drug Effect, with low baseline variability and accurate burst suppression prediction. The ability of the measures to predict Ce-prop was best for BIS.
-
Comparison of plasma compartment versus two methods for Effect compartment-controlled target-controlled infusion for propofol
Anesthesiology, 2000Co-Authors: Michel Struys, Steven L Shafer, Tom De Smet, Birgit Depoorter, Linda Versichelen, Eric Mortier, Frank J E Dumortier, Georges RollyAbstract:Background: Target-controlled infusion (TCI) systems can control the concentration in the plasma or at the site of Drug Effect. A TCI system that targets the Effect site should be able to accurately predict the time course of Drug Effect. The authors tested this by comparing the performance of three control algorithms: plasma-control TCI versus two algorithms for Effect-site control TCI, Methods: One-hundred twenty healthy women patients received propofol via TCI for 12-min at a target concentration of 5.4 mu g/ml, In all three groups, the plasma concentrations mere computed using pharmacokinetics previously reported. In group I, the TCI device controlled the plasma concentration. In groups II and III, the TCI device controlled the Effect-site concentration. In group II, the Effect site was computed using a half-life for plasma Effect-site equilibration (t(1/2) k(eo)) of 3.5 min. In group m, plasma Effect-site equilibration rate constant (k(eo)) was computed to yield a time to peak Effect of 1.6 min after bolus injection, yielding a t(1/2), k(eo) of 34 s, the time course of propofol was measured using the bispectral index, Blood pressure, ventilation, and time of loss of consciousness were measured. Results The time course of propofol Drug Effect, as measured by the bispectral index, was best predicted in group III. Targeting the Effect-site concentration shortened the time to loss of consciousness compared with the targeting plasma concentration without causing hypotension. The incidence of apnea was less in group III than in group II. Conclusion: Effect compartment-controlled TCI can be safely applied in clinical practice. A biophase model combining the Marsh kinetics and a time to peak Effect of 1.6 min accurately predicted the time course of propofol Drug Effect.
-
Comparison of spontaneous frontal EMG, EEG power spectrum and bispectral index to monitor propofol Drug Effect and emergence
Acta anaesthesiologica Scandinavica, 1998Co-Authors: Michel Struys, Linda Versichelen, Eric Mortier, D Ryckaert, J C De Mey, C. De Deyne, Georges RollyAbstract:Background: The aim of this study was to investigate the accuracy of frontal spontaneous electromyography (SEMG) and EEG spectral edge frequency (SEF 95%), median frequency (MF), relative delta power (RDELTA) and bispectral index (BIS) in monitoring loss of and return of consciousness and hypnotic Drug Effect during propofol administration at different calculated plasma target concentrations. Methods: Propofol was administered by using a target-controlled infusion at different propofol steady-state concentrations. All variables were measured simultaneously at specific calculated concentrations and endpoints. Results: Loss of consciousness was accurately monitored by BIS, SEMG and SEF 95%, and propofol Drug Effect by BIS only. Return of consciousness was predicted by BIS, MF and SEF 95%. Due to the biphasic EEG pattern of propofol and the lack of reproducible data at specific propofol concentrations, the clinical usefulness of SEF 95%, MF and RDELTA was very limited. SEMG was useful to detect loss and return of consciousness, but without predictive value. Conclusions: The BIS might be an accurate measure to monitor depth of anaesthesia and hypnotic Drug Effect. Other neurophysiologic measures have limited value to monitor depth of anaesthesia and hypnotic Drug Effect.
