Limits...
A Pharmacokinetics-Neural Mass Model (PK-NMM) for the Simulation of EEG Activity during Propofol Anesthesia.

Liang Z, Duan X, Su C, Voss L, Sleigh J, Li X - PLoS ONE (2015)

Bottom Line: The PK model was used to derive propofol effect-site drug concentrations (C(eff)) based on the actual drug infusion regimen.The correlation coefficient of PE was 0.80 ± 0.13 (mean ± standard deviation) between rEEG and sEEG for all subjects.The PK-NMM model could simulate EEG activity and might be a useful tool for understanding the action of propofol on brain activity.

View Article: PubMed Central - PubMed

Affiliation: Institute of Electrical Engineering, Yanshan University, Qinhuangdao, China.

ABSTRACT
Modeling the effects of anesthetic drugs on brain activity is very helpful in understanding anesthesia mechanisms. The aim of this study was to set up a combined model to relate actual drug levels to EEG dynamics and behavioral states during propofol-induced anesthesia. We proposed a new combined theoretical model based on a pharmacokinetics (PK) model and a neural mass model (NMM), which we termed PK-NMM--with the aim of simulating electroencephalogram (EEG) activity during propofol-induced general anesthesia. The PK model was used to derive propofol effect-site drug concentrations (C(eff)) based on the actual drug infusion regimen. The NMM model took C(eff) as the control parameter to produce simulated EEG-like (sEEG) data. For comparison, we used real prefrontal EEG (rEEG) data of nine volunteers undergoing propofol anesthesia from a previous experiment. To see how well the sEEG could describe the dynamic changes of neural activity during anesthesia, the rEEG data and the sEEG data were compared with respect to: power-frequency plots; nonlinear exponent (permutation entropy (PE)); and bispectral SynchFastSlow (SFS) parameters. We found that the PK-NMM model was able to reproduce anesthesia EEG-like signals based on the estimated drug concentration and patients' condition. The frequency spectrum indicated that the frequency power peak of the sEEG moved towards the low frequency band as anesthesia deepened. Different anesthetic states could be differentiated by the PE index. The correlation coefficient of PE was 0.80 ± 0.13 (mean ± standard deviation) between rEEG and sEEG for all subjects. Additionally, SFS could track the depth of anesthesia and the SFS of rEEG and sEEG were highly correlated with a correlation coefficient of 0.77 ± 0.13. The PK-NMM model could simulate EEG activity and might be a useful tool for understanding the action of propofol on brain activity.

Show MeSH

Related in: MedlinePlus

Diagram of the experimental design.The circle depicts the last object that could be recalled (the “object time”). The triangle depicts the time corresponding to the first number remembered during awakening (the “number time”).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4697853&req=5

pone.0145959.g003: Diagram of the experimental design.The circle depicts the last object that could be recalled (the “object time”). The triangle depicts the time corresponding to the first number remembered during awakening (the “number time”).

Mentions: In the work by Williams et al.[49], the authors performed an experiment in which nine fit human volunteers were given a brief propofol anesthetic to test conscious awareness in the absence of response to verbal command. As described more fully in this paper, prior to the surgery the volunteers were informed of the experimental protocol. Raw EEG recording was started at the beginning and lasted until the end of the experiment. The drug was infused at 150ml/h (1500mg/h) via a syringe driver. At the commencement of the infusion a verbal list of dissimilar objects was read to the participants at 30 second intervals; the time point of the last object they could remember during the induction was recorded as “object time”. The induction of anesthesia was ended when a syringe, filled with water, held between forefinger and thumb was dropped. This time point was recorded as “syringe-drop time”, and at this point the propofol infusion was ceased and the verbal list stopped. The participants were then allowed to recover and a pre-recorded tape of three-digit numbers and commands was started. The verbal commands were at 10-s intervals within the number sequences and consisted of simple commands such as “move your right foot”. The command itself lasted 5s. They were repeated for each of four limbs in a random fashion. The time point that the participant was able to respond correctly was the “command time”, at which point the experiment was terminated. The participant was asked which number they could first recall. This was recorded and the time this presented in the number sequence was recorded as “number time”. The experimental sequence is shown in Fig 3. The silver-silver chloride scalp electrodes were placed at the position of Fp1-F7 according to the 10–20 international system to produce bipolar signals. The ground electrode was placed at FpZ. The Aspect A-1000 EEG monitor (Aspect Medical Systems, Natick, MA, USA) was used to collect the real EEG signal (The sampling frequency is 256 Hz). Then the real EEG was down sampled to 100Hz for use.


A Pharmacokinetics-Neural Mass Model (PK-NMM) for the Simulation of EEG Activity during Propofol Anesthesia.

Liang Z, Duan X, Su C, Voss L, Sleigh J, Li X - PLoS ONE (2015)

Diagram of the experimental design.The circle depicts the last object that could be recalled (the “object time”). The triangle depicts the time corresponding to the first number remembered during awakening (the “number time”).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4697853&req=5

pone.0145959.g003: Diagram of the experimental design.The circle depicts the last object that could be recalled (the “object time”). The triangle depicts the time corresponding to the first number remembered during awakening (the “number time”).
Mentions: In the work by Williams et al.[49], the authors performed an experiment in which nine fit human volunteers were given a brief propofol anesthetic to test conscious awareness in the absence of response to verbal command. As described more fully in this paper, prior to the surgery the volunteers were informed of the experimental protocol. Raw EEG recording was started at the beginning and lasted until the end of the experiment. The drug was infused at 150ml/h (1500mg/h) via a syringe driver. At the commencement of the infusion a verbal list of dissimilar objects was read to the participants at 30 second intervals; the time point of the last object they could remember during the induction was recorded as “object time”. The induction of anesthesia was ended when a syringe, filled with water, held between forefinger and thumb was dropped. This time point was recorded as “syringe-drop time”, and at this point the propofol infusion was ceased and the verbal list stopped. The participants were then allowed to recover and a pre-recorded tape of three-digit numbers and commands was started. The verbal commands were at 10-s intervals within the number sequences and consisted of simple commands such as “move your right foot”. The command itself lasted 5s. They were repeated for each of four limbs in a random fashion. The time point that the participant was able to respond correctly was the “command time”, at which point the experiment was terminated. The participant was asked which number they could first recall. This was recorded and the time this presented in the number sequence was recorded as “number time”. The experimental sequence is shown in Fig 3. The silver-silver chloride scalp electrodes were placed at the position of Fp1-F7 according to the 10–20 international system to produce bipolar signals. The ground electrode was placed at FpZ. The Aspect A-1000 EEG monitor (Aspect Medical Systems, Natick, MA, USA) was used to collect the real EEG signal (The sampling frequency is 256 Hz). Then the real EEG was down sampled to 100Hz for use.

Bottom Line: The PK model was used to derive propofol effect-site drug concentrations (C(eff)) based on the actual drug infusion regimen.The correlation coefficient of PE was 0.80 ± 0.13 (mean ± standard deviation) between rEEG and sEEG for all subjects.The PK-NMM model could simulate EEG activity and might be a useful tool for understanding the action of propofol on brain activity.

View Article: PubMed Central - PubMed

Affiliation: Institute of Electrical Engineering, Yanshan University, Qinhuangdao, China.

ABSTRACT
Modeling the effects of anesthetic drugs on brain activity is very helpful in understanding anesthesia mechanisms. The aim of this study was to set up a combined model to relate actual drug levels to EEG dynamics and behavioral states during propofol-induced anesthesia. We proposed a new combined theoretical model based on a pharmacokinetics (PK) model and a neural mass model (NMM), which we termed PK-NMM--with the aim of simulating electroencephalogram (EEG) activity during propofol-induced general anesthesia. The PK model was used to derive propofol effect-site drug concentrations (C(eff)) based on the actual drug infusion regimen. The NMM model took C(eff) as the control parameter to produce simulated EEG-like (sEEG) data. For comparison, we used real prefrontal EEG (rEEG) data of nine volunteers undergoing propofol anesthesia from a previous experiment. To see how well the sEEG could describe the dynamic changes of neural activity during anesthesia, the rEEG data and the sEEG data were compared with respect to: power-frequency plots; nonlinear exponent (permutation entropy (PE)); and bispectral SynchFastSlow (SFS) parameters. We found that the PK-NMM model was able to reproduce anesthesia EEG-like signals based on the estimated drug concentration and patients' condition. The frequency spectrum indicated that the frequency power peak of the sEEG moved towards the low frequency band as anesthesia deepened. Different anesthetic states could be differentiated by the PE index. The correlation coefficient of PE was 0.80 ± 0.13 (mean ± standard deviation) between rEEG and sEEG for all subjects. Additionally, SFS could track the depth of anesthesia and the SFS of rEEG and sEEG were highly correlated with a correlation coefficient of 0.77 ± 0.13. The PK-NMM model could simulate EEG activity and might be a useful tool for understanding the action of propofol on brain activity.

Show MeSH
Related in: MedlinePlus