Brain activity complexity has a nonlinear relation to the level of propofol sedation

Boncompte, Gonzalo; Medel, Vicente; Cortínez, Luis Ignacio; Ossandón, Tomás

doi:10.1016/j.bja.2021.04.023

Cited by 24 publications

(31 citation statements)

References 37 publications

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“…Lempel-Ziv complexity was calculated using custom-made Python scripts available from previous work ( Boncompte et al, 2021 ). Briefly, the signal from each 15 s segment was binarized across the median, assigning a 1 to all values above and a 0 to all values below the threshold, which produced the symbolic signal.…”

Section: Methodsmentioning

confidence: 99%

“…Then, the number of non-redundant patterns is normalized considering the length of the signal to yield an LZc value, which ranges from 0 to 1. In general, a regular (periodic) signal showcases a low LZc (low diversity of distinct patterns) and an irregular (e.g., random) signal presents high LZc [great diversity of patterns; see Boncompte et al, 2021 for a more detailed explanation).…”

Section: Methodsmentioning

confidence: 99%

“…Broadly speaking, they attempt to characterize the amount of information or entropy in the EEG signal, i.e., how chaotic vs. predictable it is in each conscious state. One of the most promising is Lempel-Ziv complexity (LZc; Lempel and Ziv, 1976 ) which specifically quantifies the rate at which non-redundant patterns appear in an EEG signal in time ( Boncompte et al, 2021 ). LZc has exhibited strong dependence on different states of consciousness, showing high values during wakefulness, and low values when consciousness is lost due to a variety of anesthetics ( Zhang et al, 2001 ), during non-REM sleep ( Massimini et al, 2005 ) and in disorders of consciousness ( Lei et al, 2022 ).…”

Section: Introductionmentioning

confidence: 99%

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The effect of age on electroencephalogram measures of anesthesia hypnosis: A comparison of BIS, Alpha Power, Lempel-Ziv complexity and permutation entropy during propofol induction

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Boncompte

Pedemonte

et al. 2022

Front. Aging Neurosci.

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BackgroundImproving anesthesia administration for elderly population is of particular importance because they undergo considerably more surgical procedures and are at the most risk of suffering from anesthesia-related complications. Intraoperative brain monitors electroencephalogram (EEG) have proved useful in the general population, however, in elderly subjects this is contentious. Probably because these monitors do not account for the natural differences in EEG signals between young and older patients. In this study we attempted to systematically characterize the age-dependence of different EEG measures of anesthesia hypnosis.MethodsWe recorded EEG from 30 patients with a wide age range (19–99 years old) and analyzed four different proposed indexes of depth of hypnosis before, during and after loss of behavioral response due to slow propofol infusion during anesthetic induction. We analyzed Bispectral Index (BIS), Alpha Power and two entropy-related EEG measures, Lempel-Ziv complexity (LZc), and permutation entropy (PE) using mixed-effect analysis of variances (ANOVAs). We evaluated their possible age biases and their trajectories during propofol induction.ResultsAll measures were dependent on anesthesia stages. BIS, LZc, and PE presented lower values at increasing anesthetic dosage. Inversely, Alpha Power increased with increasing propofol at low doses, however this relation was reversed at greater effect-site propofol concentrations. Significant group differences between elderly patients (>65 years) and young patients were observed for BIS, Alpha Power, and LZc, but not for PE.ConclusionBIS, Alpha Power, and LZc show important age-related biases during slow propofol induction. These should be considered when interpreting and designing EEG monitors for clinical settings. Interestingly, PE did not present significant age differences, which makes it a promising candidate as an age-independent measure of hypnotic depth to be used in future monitor development.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The effect of age on electroencephalogram measures of anesthesia hypnosis: A comparison of BIS, Alpha Power, Lempel-Ziv complexity and permutation entropy during propofol induction

Biggs

Boncompte

Pedemonte

et al. 2022

Front. Aging Neurosci.

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“…Further, the “quality” of activation needs to be assessed in the future to be able to distinguish between states of increased activation or higher entropy and states of organized complexity. For instance, low doses of propofol may also lead to increases in (Lempel-Ziv) complexity when compared to an awake baseline [ 44 ]. Because the role of neural inertia seems to become more important when investigating state transitions, we need to better understand the mechanisms of the single state transitions [ 45 ].…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Anesthetic Specific EEG Dynamics during State Transitions between Loss and Return of Responsiveness

et al. 2021

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Purpose: electroencephalographic (EEG) information is used to monitor the level of cortical depression of a patient undergoing surgical intervention under general anesthesia. The dynamic state transitions into and out of anesthetic-induced loss and return of responsiveness (LOR, ROR) present a possibility to evaluate the dynamics of the EEG induced by different substances. We evaluated changes in the EEG power spectrum during anesthesia emergence for three different anesthetic regimens. We also assessed the possible impact of these changes on processed EEG parameters such as the permutation entropy (PeEn) and the cerebral state index (CSI). Methods: we analyzed the EEG from 45 patients, equally assigned to three groups. All patients were induced with propofol and the groups differed by the maintenance anesthetic regimen, i.e., sevoflurane, isoflurane, or propofol. We evaluated the EEG and parameter dynamics during LOR and ROR. For the emergence period, we focused on possible differences in the EEG dynamics in the different groups. Results: depending on the substance, the EEG emergence patterns showed significant differences that led to a substance-specific early activation of higher frequencies as indicated by the “wake” CSI values that occurred minutes before ROR in the inhalational anesthetic groups. Conclusion: our results highlight substance-specific differences in the emergence from anesthesia that can influence the EEG-based monitoring that probably have to be considered in order to improve neuromonitoring during general anesthesia.

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“…In this issue of the British Journal of Anaesthesia, Boncompte and colleagues 1 report on the changes in EEG complexity caused by modestly sedating target concentrations of propofol (0.6 and 1.2 mg ml À1 ). 1 They found an almost binary clustering between some subjects who became sleepy, as evidenced by impaired auditory discrimination, and some who did not. As expected, EEG complexity decreased slightly in those who became sleepy.…”

mentioning

confidence: 99%

Is complexity complicated?

Sleigh

Hight

2021

British Journal of Anaesthesia

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Brain activity complexity has a nonlinear relation to the level of propofol sedation

Cited by 24 publications

References 37 publications

The effect of age on electroencephalogram measures of anesthesia hypnosis: A comparison of BIS, Alpha Power, Lempel-Ziv complexity and permutation entropy during propofol induction

The effect of age on electroencephalogram measures of anesthesia hypnosis: A comparison of BIS, Alpha Power, Lempel-Ziv complexity and permutation entropy during propofol induction

Evaluation of Anesthetic Specific EEG Dynamics during State Transitions between Loss and Return of Responsiveness

Is complexity complicated?

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