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

Abstract

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.

State-related Electroencephalography Microstate Complexity during Propofol- and Esketamine-induced Unconsciousness

“…In addition, many studies have indicated that traditional EEG-based Lempel–Ziv complexity is decreased after anesthesia. 25–27 However, in our study, the Lempel–Ziv complexity based on microstate sequences showed the opposite trend. From the statistical analysis of the occurrence and duration measures of microstates in table 1, we found that the duration of most microstates is shorter compared to the awake state.…”

Sensory modality defines the relation between EEG Lempel-Ziv diversity and meaningfulness of a stimulus

“…The diversity of continuous brain activity constitutes a sensitive and robust neuronal marker of the global states of consciousness [12,13,14,15,16,17,18]. Accordingly, it has been proposed that these diversity measures are closely related with conscious experience, specifically with its richness, vividness, and temporal variability [23,24,43,44].…”

“…Nevertheless, the Lempel-Ziv diversity of continuous brain signals has also been shown to successfully predict global states of consciousness. Specifically, the diversity of continuous brain signals decreases during NREM sleep [12,13], propofolinduced anesthesia [14,15,16], and in patients suffering from disorders of consciousness [17].…”

Tracking the effects of propofol, sevoflurane and (S)-ketamine anesthesia using an unscented Kalman filter-based neural mass model

“…For GABAergic anesthetics (i.e. propofol and sevoflurane), the EEG changes from a wide band to a regular oscillation after LOC, and PE measures decrease in complexity after anesthesia [46]. However, (S)ketamine promotes abnormal excitement and high frequency power in EEG after induction.…”