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Valtonen P, Markkanen S, Järventausta K, Tenhunen M, Kalliomäki ML. In response to "Nitrous oxide inhalation: History and experiences," a letter to the Editor by Kroneberg et al. Acta Anaesthesiol Scand 2024. [PMID: 38923524 DOI: 10.1111/aas.14469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Accepted: 05/18/2024] [Indexed: 06/28/2024]
Affiliation(s)
- Petra Valtonen
- Department of Anesthesia, Tampere University Hospital, Tampere, Finland
- Wellbeing Services County of Pirkanmaa, Tampere, Finland
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Saara Markkanen
- Wellbeing Services County of Pirkanmaa, Tampere, Finland
- Department of Ear and Oral Diseases, Tampere University Hospital, Tampere, Finland
| | - Kaija Järventausta
- Wellbeing Services County of Pirkanmaa, Tampere, Finland
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
- Department of Psychiatry, Tampere University Hospital, Tampere, Finland
| | - Mirja Tenhunen
- Wellbeing Services County of Pirkanmaa, Tampere, Finland
- Department of Clinical Neurophysiology, Tampere University Hospital, Tampere, Finland
- Department of Medical Physics, Tampere University Hospital, Tampere, Finland
| | - Maija-Liisa Kalliomäki
- Department of Anesthesia, Tampere University Hospital, Tampere, Finland
- Wellbeing Services County of Pirkanmaa, Tampere, Finland
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Rozov S, Saarreharju R, Khirug S, Storvik M, Rivera C, Rantamäki T. Effects of nitrous oxide and ketamine on electrophysiological and molecular responses in the prefrontal cortex of mice: A comparative study. Eur J Pharmacol 2024; 968:176426. [PMID: 38387719 DOI: 10.1016/j.ejphar.2024.176426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 02/02/2024] [Accepted: 02/14/2024] [Indexed: 02/24/2024]
Abstract
Nitrous oxide (N2O; laughing gas) has recently reported to produce rapid antidepressant effects, but little is known about the underlying mechanisms. We performed transcriptomics, in situ hybridization, and electrophysiological studies to examine the potential shared signatures induced by 1 h inhalation of 50% N2O and a single subanesthetic dose of ketamine (10 mg/kg, i.p.) in the medial prefrontal cortex (mPFC) in adult mice. Both treatments similarly affected the transcription of several negative regulators of mitogen-activated protein kinases (MAPKs), namely, dual specificity phosphatases (DUSPs). The effects were primarily located in the pyramidal cells. Notably, the overall effects of N2O on mRNA expression were much more prominent and widespread compared to ketamine. Ketamine caused an elevation of the spiking frequency of putative pyramidal neurons and increased gamma activity (30-100 Hz) of cortical local field potentials. However, N2O produced no such effects. Spiking amplitudes and spike-to-local field potential phase locking of putative pyramidal neurons and interneurons in this brain area showed no uniform changes across treatments. Our findings suggest that N2O and subanesthetic-dose ketamine target MAPK pathway in the mPFC but produce varying acute electrophysiological responses.
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Affiliation(s)
- Stanislav Rozov
- Laboratory of Neurotherapeutics, Drug Research Program, Division of Pharmacology and Pharmacotherapy, Faculty of Pharmacy, University of Helsinki, Helsinki, 00014, Finland; SleepWell Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00014, Finland.
| | - Roosa Saarreharju
- Laboratory of Neurotherapeutics, Drug Research Program, Division of Pharmacology and Pharmacotherapy, Faculty of Pharmacy, University of Helsinki, Helsinki, 00014, Finland; SleepWell Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00014, Finland
| | - Stanislav Khirug
- Neuroscience Center, University of Helsinki, Helsinki, 00014, Finland
| | | | - Claudio Rivera
- Neuroscience Center, University of Helsinki, Helsinki, 00014, Finland; Aix Marseille Univ, INSERM, INMED, Marseille, 13007, France
| | - Tomi Rantamäki
- Laboratory of Neurotherapeutics, Drug Research Program, Division of Pharmacology and Pharmacotherapy, Faculty of Pharmacy, University of Helsinki, Helsinki, 00014, Finland; SleepWell Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00014, Finland
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Vrijdag XCE, Hallum LE, Tonks EI, van Waart H, Mitchell SJ, Sleigh JW. Support-vector classification of low-dose nitrous oxide administration with multi-channel EEG power spectra. J Clin Monit Comput 2024; 38:363-371. [PMID: 37440117 PMCID: PMC10995006 DOI: 10.1007/s10877-023-01054-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 06/25/2023] [Indexed: 07/14/2023]
Abstract
Support-vector machines (SVMs) can potentially improve patient monitoring during nitrous oxide anaesthesia. By elucidating the effects of low-dose nitrous oxide on the power spectra of multi-channel EEG recordings, we quantified the degree to which these effects generalise across participants. In this single-blind, cross-over study, 32-channel EEG was recorded from 12 healthy participants exposed to 0, 20, 30 and 40% end-tidal nitrous oxide. Features of the delta-, theta-, alpha- and beta-band power were used within a 12-fold, participant-wise cross-validation framework to train and test two SVMs: (1) binary SVM classifying EEG during 0 or 40% exposure (chance = 50%); (2) multi-class SVM classifying EEG during 0, 20, 30 or 40% exposure (chance = 25%). Both the binary (accuracy 92%) and the multi-class (accuracy 52%) SVMs classified EEG recordings at rates significantly better than chance (p < 0.001 and p = 0.01, respectively). To determine the relative importance of frequency band features for classification accuracy, we systematically removed features before re-training and re-testing the SVMs. This showed the relative importance of decreased delta power and the frontal region. SVM classification identified that the most important effects of nitrous oxide were found in the delta band in the frontal electrodes that was consistent between participants. Furthermore, support-vector classification of nitrous oxide dosage is a promising method that might be used to improve patient monitoring during nitrous oxide anaesthesia.
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Affiliation(s)
- Xavier C E Vrijdag
- Department of Anaesthesiology, School of Medicine, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.
| | - Luke E Hallum
- Department of Mechanical and Mechatronics Engineering, University of Auckland, Auckland, 1142, New Zealand
| | - Emma I Tonks
- Department of Mechanical and Mechatronics Engineering, University of Auckland, Auckland, 1142, New Zealand
| | - Hanna van Waart
- Department of Anaesthesiology, School of Medicine, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| | - Simon J Mitchell
- Department of Anaesthesiology, School of Medicine, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
- Department of Anaesthesia, Auckland City Hospital, Auckland, 1023, New Zealand
| | - Jamie W Sleigh
- Department of Anaesthesiology, School of Medicine, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
- Department of Anaesthesia, Waikato Hospital, Hamilton, 3240, New Zealand
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4
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Bong CL, Balanza GA, Khoo CEH, Tan JSK, Desel T, Purdon PL. A Narrative Review Illustrating the Clinical Utility of Electroencephalogram-Guided Anesthesia Care in Children. Anesth Analg 2023; 137:108-123. [PMID: 36729437 DOI: 10.1213/ane.0000000000006267] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The major therapeutic end points of general anesthesia include hypnosis, amnesia, and immobility. There is a complex relationship between general anesthesia, responsiveness, hemodynamic stability, and reaction to noxious stimuli. This complexity is compounded in pediatric anesthesia, where clinicians manage children from a wide range of ages, developmental stages, and body sizes, with their concomitant differences in physiology and pharmacology. This renders anesthetic requirements difficult to predict based solely on a child's age, body weight, and vital signs. Electroencephalogram (EEG) monitoring provides a window into children's brain states and may be useful in guiding clinical anesthesia management. However, many clinicians are unfamiliar with EEG monitoring in children. Young children's EEGs differ substantially from those of older children and adults, and there is a lack of evidence-based guidance on how and when to use the EEG for anesthesia care in children. This narrative review begins by summarizing what is known about EEG monitoring in pediatric anesthesia care. A key knowledge gap in the literature relates to a lack of practical information illustrating the utility of the EEG in clinical management. To address this gap, this narrative review illustrates how the EEG spectrogram can be used to visualize, in real time, brain responses to anesthetic drugs in relation to hemodynamic stability, surgical stimulation, and other interventions such as cardiopulmonary bypass. This review discusses anesthetic management principles in a variety of clinical scenarios, including infants, children with altered conscious levels, children with atypical neurodevelopment, children with hemodynamic instability, children undergoing total intravenous anesthesia, and those undergoing cardiopulmonary bypass. Each scenario is accompanied by practical illustrations of how the EEG can be visualized to help titrate anesthetic dosage to avoid undersedation or oversedation when patients experience hypotension or other physiological challenges, when surgical stimulation increases, and when a child's anesthetic requirements are otherwise less predictable. Overall, this review illustrates how well-established clinical management principles in children can be significantly complemented by the addition of EEG monitoring, thus enabling personalized anesthesia care to enhance patient safety and experience.
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Affiliation(s)
- Choon Looi Bong
- From the Department of Pediatric Anesthesia, KK Women's and Children's Hospital, Duke-NUS Medical School, Singapore
| | - Gustavo A Balanza
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Charis Ern-Hui Khoo
- From the Department of Pediatric Anesthesia, KK Women's and Children's Hospital, Duke-NUS Medical School, Singapore
| | - Josephine Swee-Kim Tan
- From the Department of Pediatric Anesthesia, KK Women's and Children's Hospital, Duke-NUS Medical School, Singapore
| | - Tenzin Desel
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Patrick Lee Purdon
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
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Brain function changes reveal rapid antidepressant effects of nitrous oxide for treatment-resistant depression:Evidence from task-state EEG. Psychiatry Res 2023; 322:115072. [PMID: 36791487 DOI: 10.1016/j.psychres.2023.115072] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 01/15/2023] [Accepted: 01/22/2023] [Indexed: 01/28/2023]
Abstract
Nitrous oxide has rapid antidepressant effects in patients with treatment-resistant depression (TRD), but its underlying mechanisms of therapeutic actions are not well understood. Moreover, most of the current studies lack objective biological indicators to evaluate the changes of nitrous oxide-induced brain function for TRD. Therefore, this study assessed the effect of nitrous oxide on brain function for TRD based on event-related potential (ERP) components and functional connectivity networks (FCNs) methods. In this randomized, longitudinal, placebo-controlled trial, all TRD participants were divided into two groups to receive either a 1-hour inhalation of nitrous oxide or a placebo treatment, and they took part in the same task-state electroencephalogram (EEG) experiment before and after treatment. The experimental results showed that nitrous oxide improved depressive symptoms better than placebo in terms of 17-Hamilton Depression Rating Scale score (HAMD-17). Statistical analysis based on ERP components showed that nitrous oxide-induced significant differences in amplitude and latency of N1, P1, N2, P2. In addition, increased brain functional connectivity was found after nitrous oxide treatment. And the change of network metrics has a significant correlation with decreased depressive symptoms. These findings may suggest that nitrous oxide improves depression symptoms for TRD by modifying brain function.
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Electroencephalogram Features of Perioperative Neurocognitive Disorders in Elderly Patients: A Narrative Review of the Clinical Literature. Brain Sci 2022; 12:brainsci12081073. [PMID: 36009136 PMCID: PMC9405602 DOI: 10.3390/brainsci12081073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 08/04/2022] [Accepted: 08/09/2022] [Indexed: 11/16/2022] Open
Abstract
Postoperative neurocognitive disorder (PND) is a common postoperative complication, particularly in older patients. Electroencephalogram (EEG) monitoring, a non-invasive technique with a high spatial-temporal resolution, can accurately characterize the dynamic changes in brain function during the perioperative period. Current clinical studies have confirmed that the power density of alpha oscillation during general anesthesia decreased with age, which was considered to be associated with increased susceptibility to PND in the elderly. However, evidence on whether general anesthesia under EEG guidance results in a lower morbidity of PND is still contradictory. This is one of the reasons that common indicators of the depth of anesthesia were limitedly derived from EEG signals in the frontal lobe. The variation of multi-channel EEG features during the perioperative period has the potential to highlight the occult structural and functional abnormalities of the subcortical-cortical neurocircuit. Therefore, we present a review of the application of multi-channel EEG monitoring to predict the incidence of PND in older patients. The data confirmed that the abnormal variation in EEG power and functional connectivity between distant brain regions was closely related to the incidence and long-term poor outcomes of PND in older adults.
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Thalamic T-Type Calcium Channels as Targets for Hypnotics and General Anesthetics. Int J Mol Sci 2022; 23:ijms23042349. [PMID: 35216466 PMCID: PMC8876360 DOI: 10.3390/ijms23042349] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 12/19/2022] Open
Abstract
General anesthetics mainly act by modulating synaptic inhibition on the one hand (the potentiation of GABA transmission) or synaptic excitation on the other (the inhibition of NMDA receptors), but they can also have effects on numerous other proteins, receptors, and channels. The effects of general anesthetics on ion channels have been the subject of research since the publication of reports of direct actions of these drugs on ion channel proteins. In particular, there is considerable interest in T-type voltage-gated calcium channels that are abundantly expressed in the thalamus, where they control patterns of cellular excitability and thalamocortical oscillations during awake and sleep states. Here, we summarized and discussed our recent studies focused on the CaV3.1 isoform of T-channels in the nonspecific thalamus (intralaminar and midline nuclei), which acts as a key hub through which natural sleep and general anesthesia are initiated. We used mouse genetics and in vivo and ex vivo electrophysiology to study the role of thalamic T-channels in hypnosis induced by a standard general anesthetic, isoflurane, as well as novel neuroactive steroids. From the results of this study, we conclude that CaV3.1 channels contribute to thalamocortical oscillations during anesthetic-induced hypnosis, particularly the slow-frequency range of δ oscillations (0.5–4 Hz), by generating “window current” that contributes to the resting membrane potential. We posit that the role of the thalamic CaV3.1 isoform of T-channels in the effects of various classes of general anesthetics warrants consideration.
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Kuroiwa K, Harano N, Shigeyama-Tada Y, Ono K, Watanabe S. Effects of inhalation sedation with nitrous oxide on intraoral senses. PEDIATRIC DENTAL JOURNAL 2021. [DOI: 10.1016/j.pdj.2021.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Neural Dynamics in Primate Cortex during Exposure to Subanesthetic Concentrations of Nitrous Oxide. eNeuro 2021; 8:ENEURO.0479-20.2021. [PMID: 34135005 PMCID: PMC8281265 DOI: 10.1523/eneuro.0479-20.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 05/07/2021] [Accepted: 05/31/2021] [Indexed: 11/21/2022] Open
Abstract
Nitrous oxide (N2O) is a hypnotic gas with antidepressant and psychedelic properties at subanesthetic concentrations. Despite long-standing clinical use, there is insufficient understanding of its effect on neural dynamics and cortical processing, which is important for mechanistic understanding of its therapeutic effects. We administered subanesthetic (70%), inhaled N2O and studied the dynamic changes of spiking rate, spectral content, and somatosensory information representation in primary motor cortex (M1) in two male rhesus macaques implanted with Utah microelectrode arrays in the hand area of M1. The average sorted multiunit spiking rate in M1 increased from 8.1 ± 0.99 to 10.6 ± 1.3 Hz in Monkey W (p < 0.001) and from 5.6 ± 0.87 to 7.0 ± 1.1 Hz in Monkey N (p = 0.003). Power spectral densities increased in beta- and gamma-band power. To evaluate somatosensory content in M1 as a surrogate of information transfer, fingers were lightly brushed and classified using a naive Bayes classifier. In both monkeys, the proportion of correctly classified fingers dropped from 0.50 ± 0.06 before N2O inhalation to 0.34 ± 0.03 during N2O inhalation (p = 0.018), although some fingers continued to be correctly classified (p = 0.005). The decrease in correct classifications corresponded to decreased modulation depth for the population (p = 0.005) and fewer modulated units (p = 0.046). However, the increased single-unit firing rate was not correlated with its modulation depth (R2 < 0.001, p = 0.93). These data suggest that N2O degrades information transfer, although no clear relationship was found between neuronal tuning and N2O-induced changes in firing rate.
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McGuigan S, Evered L, Silbert B, Scott DA, Cormack JR, Devapalasundaram A, Liley DTJ. Comparison of the Spectral Features of the Frontal Electroencephalogram in Patients Receiving Xenon and Sevoflurane General Anesthesia. Anesth Analg 2021; 133:1269-1279. [PMID: 34081045 DOI: 10.1213/ane.0000000000005608] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Depth-of-anesthesia monitoring is often utilized for patients receiving xenon anesthesia. Processed electroencephalogram (EEG) depth-of-anesthesia monitoring relies to a significant extent on frequency domain analysis of the frontal EEG, and there is evidence that the spectral features observed under anesthesia vary significantly between anesthetic agents. The spectral features of the EEG during xenon anesthesia for a surgical procedure have not previously been described. METHODS Twenty-four participants scheduled for general anesthesia for lithotripsy were randomized to receive either xenon anesthesia or sevoflurane anesthesia. Frontal EEG recordings were obtained from each participant via the Brain Anesthesia Response Monitor (BARM). Twenty-two EEG recordings were suitable for analysis: 11 in participants who received sevoflurane and 11 in participants who received xenon. Spectrograms for the duration of the anesthetic episode were produced for each participant. Group-level spectral analysis was calculated for two 30-second EEG epochs: one recorded at awake baseline and the other during maintenance anesthesia. A linear mixed-effects model was utilized to compare the changes in 5 frequency bands from baseline to maintenance between the 2 groups. RESULTS The spectrograms of sevoflurane participants illustrate an increase in frontal delta (0.5-4 Hz), theta (4-8 Hz), and alpha (8-13 Hz) band power during maintenance anesthesia. In contrast, spectrograms of the xenon participants did not illustrate an increase in alpha power. The results of the linear mixed-effects model indicate that both agents were associated with a significant increase in delta power from baseline to maintenance. There was no significant difference in the magnitude of this increase observed between the agents. In contrast, sevoflurane anesthesia was associated with significantly greater absolute power in the theta, alpha, and beta (13-30 Hz) bands when compared to xenon. In terms of relative power, xenon was associated with a significant increase in delta power compared to sevoflurane, while sevoflurane was associated with greater increases in relative theta, alpha, and beta power. CONCLUSIONS Both xenon anesthesia and sevoflurane anesthesia were associated with significant increases in delta power. Sevoflurane anesthesia was also associated with increases in theta, alpha, and beta power, while xenon anesthesia was associated with greater consolidation of power in the delta band. Xenon anesthesia and sevoflurane anesthesia are associated with distinct spectral features. These findings suggest that appropriate depth-of-anesthesia monitoring may require the development of agent-specific spectral measures of unconsciousness.
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Affiliation(s)
- Steven McGuigan
- From the Department of Anesthesia and Acute Pain Medicine, St. Vincent's Hospital, Melbourne, Australia.,the Department of Medicine, Dentistry and Health Sciences, University of Melbourne, Australia
| | - Lisbeth Evered
- From the Department of Anesthesia and Acute Pain Medicine, St. Vincent's Hospital, Melbourne, Australia.,the Department of Medicine, Dentistry and Health Sciences, University of Melbourne, Australia
| | - Brendan Silbert
- From the Department of Anesthesia and Acute Pain Medicine, St. Vincent's Hospital, Melbourne, Australia.,the Department of Medicine, Dentistry and Health Sciences, University of Melbourne, Australia
| | - David A Scott
- From the Department of Anesthesia and Acute Pain Medicine, St. Vincent's Hospital, Melbourne, Australia.,the Department of Medicine, Dentistry and Health Sciences, University of Melbourne, Australia
| | - John R Cormack
- From the Department of Anesthesia and Acute Pain Medicine, St. Vincent's Hospital, Melbourne, Australia
| | - Abarna Devapalasundaram
- From the Department of Anesthesia and Acute Pain Medicine, St. Vincent's Hospital, Melbourne, Australia
| | - David T J Liley
- the Department of Medicine, Dentistry and Health Sciences, University of Melbourne, Australia
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Automated Classification of Mental Arithmetic Tasks Using Recurrent Neural Network and Entropy Features Obtained from Multi-Channel EEG Signals. ELECTRONICS 2021. [DOI: 10.3390/electronics10091079] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The automated classification of cognitive workload tasks based on the analysis of multi-channel EEG signals is vital for human–computer interface (HCI) applications. In this paper, we propose a computerized approach for categorizing mental-arithmetic-based cognitive workload tasks using multi-channel electroencephalogram (EEG) signals. The approach evaluates various entropy features, such as the approximation entropy, sample entropy, permutation entropy, dispersion entropy, and slope entropy, from each channel of the EEG signal. These features were fed to various recurrent neural network (RNN) models, such as long-short term memory (LSTM), bidirectional LSTM (BLSTM), and gated recurrent unit (GRU), for the automated classification of mental-arithmetic-based cognitive workload tasks. Two cognitive workload classification strategies (bad mental arithmetic calculation (BMAC) vs. good mental arithmetic calculation (GMAC); and before mental arithmetic calculation (BFMAC) vs. during mental arithmetic calculation (DMAC)) are considered in this work. The approach was evaluated using the publicly available mental arithmetic task-based EEG database. The results reveal that our proposed approach obtained classification accuracy values of 99.81%, 99.43%, and 99.81%, using the LSTM, BLSTM, and GRU-based RNN classifiers, respectively for the BMAC vs. GMAC cognitive workload classification strategy using all entropy features and a 10-fold cross-validation (CV) technique. The slope entropy features combined with each RNN-based model obtained higher classification accuracy compared with other entropy features for the classification of the BMAC vs. GMAC task. We obtained the average classification accuracy values of 99.39%, 99.44%, and 99.63% for the classification of the BFMAC vs. DMAC tasks, using the LSTM, BLSTM, and GRU classifiers with all entropy features and a hold-out CV scheme. Our developed automated mental arithmetic task system is ready to be tested with more databases for real-world applications.
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An Electroencephalogram Metric of Temporal Complexity Tracks Psychometric Impairment Caused by Low-dose Nitrous Oxide. Anesthesiology 2021; 134:202-218. [PMID: 33433619 DOI: 10.1097/aln.0000000000003628] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Nitrous oxide produces non-γ-aminobutyric acid sedation and psychometric impairment and can be used as scientific model for understanding mechanisms of progressive cognitive disturbances. Temporal complexity of the electroencephalogram may be a sensitive indicator of these effects. This study measured psychometric performance and the temporal complexity of the electroencephalogram in participants breathing low-dose nitrous oxide. METHODS In random order, 20, 30, and 40% end-tidal nitrous oxide was administered to 12 participants while recording 32-channel electroencephalogram and psychometric function. A novel metric quantifying the spatial distribution of temporal electroencephalogram complexity, comprised of (1) absolute cross-correlation calculated between consecutive 0.25-s time samples; 2) binarizing these cross-correlation matrices using the median of all channels as threshold; (3) using quantitative recurrence analysis, the complexity in temporal changes calculated by the Shannon entropy of the probability distribution of the diagonal line lengths; and (4) overall spatial extent and intensity of brain complexity, was quantified by calculating median temporal complexity of channels whose complexities were above 1 at baseline. This region approximately overlay the brain's default mode network, so this summary statistic was termed "default-mode-network complexity." RESULTS Nitrous oxide concentration correlated with psychometric impairment (r = 0.50, P < 0.001). Baseline regional electroencephalogram complexity at midline was greater than in lateral temporal channels (1.33 ± 0.14 bits vs. 0.81 ± 0.12 bits, P < 0.001). A dose of 40% N2O decreased midline (mean difference [95% CI], 0.20 bits [0.09 to 0.31], P = 0.002) and prefrontal electroencephalogram complexity (mean difference [95% CI], 0.17 bits [0.08 to 0.27], P = 0.002). The lateral temporal region did not change significantly (mean difference [95% CI], 0.14 bits [-0.03 to 0.30], P = 0.100). Default-mode-network complexity correlated with N2O concentration (r = -0.55, P < 0.001). A default-mode-network complexity mixed-effects model correlated with psychometric impairment (r2 = 0.67; receiver operating characteristic area [95% CI], 0.72 [0.59 to 0.85], P < 0.001). CONCLUSIONS Temporal complexity decreased most markedly in medial cortical regions during low-dose nitrous oxide exposures, and this change tracked psychometric impairment. EDITOR’S PERSPECTIVE
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Eagleman S, MacIver MB. Molecular Diversity of Anesthetic Actions Is Evident in Electroencephalogram Effects in Humans and Animals. Int J Mol Sci 2021; 22:ijms22020495. [PMID: 33419036 PMCID: PMC7839978 DOI: 10.3390/ijms22020495] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 12/28/2020] [Accepted: 01/04/2021] [Indexed: 12/14/2022] Open
Abstract
Anesthetic agents cause unique electroencephalogram (EEG) activity resulting from actions on their diverse molecular targets. Typically to produce balanced anesthesia in the clinical setting, several anesthetic and adjuvant agents are combined. This creates challenges for the clinical use of intraoperative EEG monitoring, because computational approaches are mostly limited to spectral analyses and different agents and combinations produce different EEG responses. Thus, testing of many combinations of agents is needed to generate accurate, protocol independent analyses. Additionally, most studies to develop new computational approaches take place in young, healthy adults and electrophysiological responses to anesthetics vary widely at the extremes of age, due to physiological brain differences. Below, we discuss the challenges associated with EEG biomarker identification for anesthetic depth based on the diversity of molecular targets. We suggest that by focusing on the generalized effects of anesthetic agents on network activity, we can create paths for improved universal analyses.
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Sun Y, Wei C, Cui V, Xiu M, Wu A. Electroencephalography: Clinical Applications During the Perioperative Period. Front Med (Lausanne) 2020; 7:251. [PMID: 32582735 PMCID: PMC7296088 DOI: 10.3389/fmed.2020.00251] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 05/11/2020] [Indexed: 12/28/2022] Open
Abstract
Electroencephalography (EEG) monitoring has become technically feasible in daily clinical anesthesia practice. EEG is a sensitive method for detecting neurophysiological changes in the brain and represents an important frontier in the monitoring and treatment of patients in the perioperative period. In this review, we briefly introduce the essential principles of EEG. We review EEG application during anesthesia practice in the operating room, including the use of processed EEG in depth of anesthesia assessment, raw EEG monitoring in recognizing brain states under different anesthetic agents, the use of EEG in the prevention of perioperative neurocognitive disorders and detection of cerebral ischemia. We then discuss EEG utilization in the intensive care units, including the use of EEG in sedative level titration and prognostication of clinical outcomes. Existing literature provides insight into both the advances and challenges of the clinical applications of EEG. Future study is clearly needed to elucidate the precise EEG features that can reliably optimize perioperative care for individual patients.
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Affiliation(s)
- Yi Sun
- Department of Anesthesiology, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Changwei Wei
- Department of Anesthesiology, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Victoria Cui
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, United States
| | - Meihong Xiu
- Peking University HuiLongGuan Clinical Medical School, Beijing HuiLongGuan Hospital, Beijing, China
| | - Anshi Wu
- Department of Anesthesiology, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
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Park HS, Kim YS, Kim SH, Jeon AR, Kim SE, Choi WJ. Comparison of electroencephalogram between propofol- and thiopental-induced anesthesia for awareness risk in pregnant women. Sci Rep 2020; 10:6192. [PMID: 32277117 PMCID: PMC7148347 DOI: 10.1038/s41598-020-62999-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 03/21/2020] [Indexed: 12/27/2022] Open
Abstract
There have been few comparative studies using electroencephalogram (EEG) spectral characteristics during the induction of general anesthesia for cesarean section. This retrospective study investigated the differences in the depth of anesthesia through EEG analysis between propofol- and thiopental-induced anesthesia. We reviewed data of 42 patients undergoing cesarean section who received either thiopental (5 mg/kg) or propofol (2 mg/kg). EEG data were extracted from the bispectral index (BIS) monitor, and 10-second segments were selected from the following sections: 1) Stage I, BIS below 60 after induction; 2) Stage II, after intubation completion; 3) Stage III, end-tidal sevoflurane above 0 vol%. The risk of awareness was represented by the BIS and entropy measures. In Stage III, the thiopental group (n = 20) showed significantly higher BIS value than the propofol group (n = 22) (67.9 [18.66] vs 44.5 [20.63], respectively, p = 0.002). The thiopental group had decreased slow-delta oscillations and increased beta-oscillations as compared to the propofol group in Stages II and III (p < 0.05). BIS, spectral entropy, and Renyi permutation entropy were also higher in the thiopental group at Stages II and III (p < 0.05). In conclusion, frontal spectral EEG analysis demonstrated that propofol induction maintained a deeper anesthesia than thiopental in pregnant women.
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Affiliation(s)
- Hee-Sun Park
- Department of Anesthesiology and Pain Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - Yeon-Su Kim
- Department of Electronics and Control Engineering, Hanbat National University, Daejeon, Korea
| | - Sung-Hoon Kim
- Department of Anesthesiology and Pain Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - A-Rom Jeon
- Department of Anesthesiology and Pain Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - Seong-Eun Kim
- Department of Electronics and Control Engineering, Hanbat National University, Daejeon, Korea.
| | - Woo-Jong Choi
- Department of Anesthesiology and Pain Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
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Rantamäki T, Kohtala S. Encoding, Consolidation, and Renormalization in Depression: Synaptic Homeostasis, Plasticity, and Sleep Integrate Rapid Antidepressant Effects. Pharmacol Rev 2020; 72:439-465. [DOI: 10.1124/pr.119.018697] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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Puchner WF, Dünser MW, Paulus P, Neuner MP, Mayer CL, Pomberger IM, Hackl R, Meier JM. A comparative study on adequate anesthesia depth: clinical judgement and the Narcotrend® measurement. Can J Anaesth 2020; 67:664-673. [PMID: 32128723 PMCID: PMC7214482 DOI: 10.1007/s12630-020-01602-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 11/26/2019] [Accepted: 12/04/2019] [Indexed: 12/19/2022] Open
Abstract
Purpose To compare the clinical judgement of electroencephalogram (EEG)-naïve anesthesiologists with an EEG-based measurement of anesthetic depth (AD) using the Narcotrend® monitor. Methods In this prospective cohort study including 600 patients, AD during stable anesthesia was assessed by clinical judgement of the attending, EEG-blinded anesthesiologist (using a scale staging the AD as mid-adequate, adequate but fairly deep, or adequate but fairly light) and by simultaneously recorded Narcotrend measurements. Results In 42% of patients (n = 250), the anesthesiologist’s clinical judgement was in agreement with anesthetic levels as measured by the Narcotrend monitor. In 46% of patients (n = 274), the anesthesiologist’s judgement and the Narcotrend monitor differed by one AD level (minor discordance). Major discordance was observed in 76 (13%) measurements (judged deeper than measured, n = 29 [5%]; judged lighter than measured, n = 47 [8%]). In 7% of patients (n = 44), the Narcotrend index was outside the limits of adequate AD (too deep, n = 28 [5%]; too superficial, n = 16 [3%]). The overall level of agreement between the anesthesiologist’s judgement and the Narcotrend monitor was not statistically significant (Cohen’s kappa, −0.039; P = 0.17). Using a random forests algorithm, age, mean blood pressure, the American Society of Anesthesiologists classification, body mass index, and frailty were the variables with the highest relative feature importance to predict the level of agreement. Conclusion These results suggest that clinical judgement of AD during stable anesthesia was not in agreement with EEG-based assessment of anesthetic depth in 58% of cases. Nevertheless, this finding could be influenced by the lack of validated scales to clinically judge AD. Trial registration www.clinicaltrials.gov (NCT02766894); registered 10 May, 2016.
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Affiliation(s)
- Wolfgang F Puchner
- Department of Anesthesiology and Intensive Care, Kepler University Hospital and Johannes Kepler University, Krankenhausstraße 9, 4021, Linz, Austria.
| | - Martin W Dünser
- Department of Anesthesiology and Intensive Care, Kepler University Hospital and Johannes Kepler University, Krankenhausstraße 9, 4021, Linz, Austria
| | - Patrick Paulus
- Department of Anesthesiology and Intensive Care, Kepler University Hospital and Johannes Kepler University, Krankenhausstraße 9, 4021, Linz, Austria
| | - Markus P Neuner
- Department of Anesthesiology and Intensive Care, Kepler University Hospital and Johannes Kepler University, Krankenhausstraße 9, 4021, Linz, Austria
| | - Charlotte L Mayer
- Department of Anesthesiology and Intensive Care, Kepler University Hospital and Johannes Kepler University, Krankenhausstraße 9, 4021, Linz, Austria
| | - Irmgard M Pomberger
- Department of Anesthesiology and Intensive Care, Kepler University Hospital and Johannes Kepler University, Krankenhausstraße 9, 4021, Linz, Austria
| | - Ruth Hackl
- Department of Anesthesiology and Intensive Care, Kepler University Hospital and Johannes Kepler University, Krankenhausstraße 9, 4021, Linz, Austria
| | - Jens M Meier
- Department of Anesthesiology and Intensive Care, Kepler University Hospital and Johannes Kepler University, Krankenhausstraße 9, 4021, Linz, Austria
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Lee JM, Kim PJ, Kim HG, Hyun HK, Kim YJ, Kim JW, Shin TJ. Analysis of brain connectivity during nitrous oxide sedation using graph theory. Sci Rep 2020; 10:2354. [PMID: 32047246 PMCID: PMC7012909 DOI: 10.1038/s41598-020-59264-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 01/27/2020] [Indexed: 01/13/2023] Open
Abstract
Nitrous oxide, the least potent inhalation anesthetic, is widely used for conscious sedation. Recently, it has been reported that the occurrence of anesthetic-induced loss of consciousness decreases the interconnection between brain regions, resulting in brain network changes. However, few studies have investigated these changes in conscious sedation using nitrous oxide. Therefore, the present study aimed to use graph theory to analyze changes in brain networks during nitrous oxide sedation. Participants were 20 healthy volunteers (10 men and 10 women, 20–40 years old) with no history of systemic disease. We acquired electroencephalogram (EEG) recordings of 32 channels during baseline, nitrous oxide inhalation sedation, and recovery. EEG epochs from the baseline and the sedation state (50% nitrous oxide) were extracted and analyzed with the network connection parameters of graph theory. Analysis of 1/f dynamics, revealed a steeper slope while in the sedation state than during the baseline. Network connectivity parameters showed significant differences between the baseline and sedation state, in delta, alpha1, alpha2, and beta2 frequency bands. The most pronounced differences in functional distance during nitrous oxide sedation were observed in the alpha1 and alpha2 frequency bands. Change in 1/f dynamics indicates that changes in brain network systems occur during nitrous oxide administration. Changes in network parameters imply that nitrous oxide interferes with the efficiency of information integration in the frequency bands important for cognitive processes and attention tasks. Alteration of brain network during nitrous oxide administration may be associated to the sedative mechanism of nitrous oxide.
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Affiliation(s)
- Ji-Min Lee
- Department of Pediatric Dentistry and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - Pil-Jong Kim
- Biomedical Knowledge Engineering Laboratory, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - Hong-Gee Kim
- Biomedical Knowledge Engineering Laboratory, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - Hong-Keun Hyun
- Department of Pediatric Dentistry and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - Young Jae Kim
- Department of Pediatric Dentistry and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - Jung-Wook Kim
- Department of Pediatric Dentistry and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - Teo Jeon Shin
- Department of Pediatric Dentistry and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
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Source-level Cortical Power Changes for Xenon and Nitrous Oxide-induced Reductions in Consciousness in Healthy Male Volunteers. Anesthesiology 2020; 132:1017-1033. [PMID: 32032094 DOI: 10.1097/aln.0000000000003169] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Investigations of the electrophysiology of gaseous anesthetics xenon and nitrous oxide are limited revealing inconsistent frequency-dependent alterations in spectral power and functional connectivity. Here, the authors describe the effects of sedative, equivalent, stepwise levels of xenon and nitrous oxide administration on oscillatory source power using a crossover design to investigate shared and disparate mechanisms of gaseous xenon and nitrous oxide anesthesia. METHODS Twenty-one healthy males underwent simultaneous magnetoencephalography and electroencephalography recordings. In separate sessions, sedative, equivalent subanesthetic doses of gaseous anesthetic agents nitrous oxide and xenon (0.25, 0.50, and 0.75 equivalent minimum alveolar concentration-awake [MACawake]) and 1.30 MACawake xenon (for loss of responsiveness) were administered. Source power in various frequency bands were computed and statistically assessed relative to a conscious/pre-gas baseline. RESULTS Observed changes in spectral-band power (P < 0.005) were found to depend not only on the gas delivered, but also on the recording modality. While xenon was found to increase low-frequency band power only at loss of responsiveness in both source-reconstructed magnetoencephalographic (delta, 208.3%, 95% CI [135.7, 281.0%]; theta, 107.4%, 95% CI [63.5, 151.4%]) and electroencephalographic recordings (delta, 260.3%, 95% CI [225.7, 294.9%]; theta, 116.3%, 95% CI [72.6, 160.0%]), nitrous oxide only produced significant magnetoencephalographic high-frequency band increases (low gamma, 46.3%, 95% CI [34.6, 57.9%]; high gamma, 45.7%, 95% CI [34.5, 56.8%]). Nitrous oxide-not xenon-produced consistent topologic (frontal) magnetoencephalographic reductions in alpha power at 0.75 MACawake doses (44.4%; 95% CI [-50.1, -38.6%]), whereas electroencephalographically nitrous oxide produced maximal reductions in alpha power at submaximal levels (0.50 MACawake, -44.0%; 95% CI [-48.1,-40.0%]). CONCLUSIONS Electromagnetic source-level imaging revealed widespread power changes in xenon and nitrous oxide anesthesia, but failed to reveal clear universal features of action for these two gaseous anesthetics. Magnetoencephalographic and electroencephalographic power changes showed notable differences which will need to be taken into account to ensure the accurate monitoring of brain state during anaesthesia.
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20
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Eagleman SL, Chander D, Reynolds C, Ouellette NT, MacIver MB. Nonlinear dynamics captures brain states at different levels of consciousness in patients anesthetized with propofol. PLoS One 2019; 14:e0223921. [PMID: 31665174 PMCID: PMC6821075 DOI: 10.1371/journal.pone.0223921] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 10/01/2019] [Indexed: 12/31/2022] Open
Abstract
The information processing capability of the brain decreases during unconscious states. Capturing this decrease during anesthesia-induced unconsciousness has been attempted using standard spectral analyses as these correlate relatively well with breakdowns in corticothalamic networks. Much of this work has involved the use of propofol to perturb brain activity, as it is one of the most widely used anesthetics for routine surgical anesthesia. Propofol administration alone produces EEG spectral characteristics similar to most hypnotics; however, inter-individual and drug variation render spectral measures inconsistent. Complexity measures of EEG signals could offer better measures to distinguish brain states, because brain activity exhibits nonlinear behavior at several scales during transitions of consciousness. We tested the potential of complexity analyses from nonlinear dynamics to identify loss and recovery of consciousness at clinically relevant timepoints. Patients undergoing propofol general anesthesia for various surgical procedures were identified as having changes in states of consciousness by the loss and recovery of response to verbal stimuli after induction and upon cessation of anesthesia, respectively. We demonstrate that nonlinear dynamics analyses showed more significant differences between consciousness states than spectral measures. Notably, attractors in conscious and anesthesia-induced unconscious states exhibited significantly different shapes. These shapes have implications for network connectivity, information processing, and the total number of states available to the brain at these different levels. They also reflect some of our general understanding of the network effects of consciousness in a way that spectral measures cannot. Thus, complexity measures could provide a universal means for reliably capturing depth of consciousness based on EEG changes at the beginning and end of anesthesia administration.
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Affiliation(s)
- Sarah L. Eagleman
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, California, United States of America
- * E-mail:
| | - Divya Chander
- Department of Medicine, Stanford University School of Medicine, Stanford, California, United States of America
| | - Christina Reynolds
- Department of Neurology, Oregon Health Sciences University, Portland, Oregon, United States of America
- National Radio Astronomy Observatory, Charlottesville, VA, United States of America
| | - Nicholas T. Ouellette
- Department of Civil and Environmental Engineering, Stanford University, Stanford, California, United States of America
| | - M. Bruce MacIver
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, California, United States of America
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Romagnoli S, Franchi F, Ricci Z. Processed EEG monitoring for anesthesia and intensive care practice. Minerva Anestesiol 2019; 85:1219-1230. [PMID: 31630505 DOI: 10.23736/s0375-9393.19.13478-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Individual response to sedatives and hypnotics is characterized by high variability and the identification of a personalized dose during anesthesia in the operating room and during sedation in the intensive care unit may have beneficial effects. Although the brain is the main target of general intravenous and inhaled anesthetic agents, electroencephalography (EEG) is not routinely utilized to explore cerebral response to sedation and anesthesia probably because EEG trace reading is complex and requires encephalographers' skills. Automated processing algorithms (processed EEG, pEEG) of raw EEG traces provide easy-to-use indices that can be utilized to optimize anesthetic management. A large number of high-quality studies and the recommendations of international scientific societies have confirmed the deleterious consequences of inadequate or excessively deep anesthesia (and sedation) level. In this context, anesthesia in the operating rooms and moderate/deep sedation in intensive care units driven by pEEG monitors could become a standard practice in the near future. The aim of the present review was to provide an overview of current knowledge and debate on available technologies for pEEG monitoring and their role in clinical practice for anesthesia and sedation.
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Affiliation(s)
- Stefano Romagnoli
- Section of Anesthesiology and Intensive Care, Department of Health Science, University of Florence, Florence, Italy - .,Department of Anesthesiology and Intensive Care, Careggi University Hospital, Florence, Italy -
| | - Federico Franchi
- Department of Medicine, Surgery and Neuroscience, Anesthesiology and Intensive Care, University Hospital of Siena, Siena, Italy
| | - Zaccaria Ricci
- Unit of Pediatric Cardiac Intensive Care, Department of Cardiology and Cardiac Surgery, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
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22
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He L, Wang X, Zheng S. Determination of the minimal alveolar concentration of sevoflurane associated with isoelectric electroencephalogram in children: A prospective, randomized, double-blind study. Paediatr Anaesth 2018; 28:1043-1049. [PMID: 30281182 DOI: 10.1111/pan.13503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Revised: 08/28/2018] [Accepted: 08/30/2018] [Indexed: 11/30/2022]
Abstract
OBJECTIVE We investigated the minimal alveolar concentration (MAC) of sevoflurane associated with the occurrence of isoelectric electroencephalogram in 50% of children under steady-state conditions (MAC IE). The MAC IE was determined in 100% oxygen and with the addition of 50% nitrous oxide or after the injection of fentanyl. METHODS Seventy-two children (ASA I or II, age 3-8 years) undergoing elective surgery were allocated to one of three groups: in 100% oxygen (group O2 ), in 50% oxygen and 50% nitrous oxide (group N2 O), or in 100% oxygen with a bolus of 3 μg/kg fentanyl (group FENTANYL). The state of isoelectric EEG was considered as significant when a burst suppression ratio of 100% lasted for >1 minute. The MAC IE was determined by the Dixon's up-and-down method after a 15-minute period with a stable endtidal concentration of sevoflurane. The concentration of sevoflurane was determined by the electroencephalogram of the previous patient: increase of 0.2% if isoelectric EEG were absent or decrease of 0.2% if isoelectric EEG were present. RESULTS The MAC IE in group O2 (MAC IEO2 ) was 5.30 (5.12-5.48)% (median [95% CI]). The MAC IE in group N2 O (MAC IEN2O ) was 5.83 (5.67-5.99)%. The MAC IE in group FENTANYL (MAC IEFENTANYL ) was 5.37 (5.21-5.53)%, which was close to MAC IEO2 . CONCLUSION The MAC IE of sevoflurane calculated in 100% O2 was 5.30% in children. Addition of 50% N2 O modestly increased MAC IE of sevoflurane, while 3 μg/kg fentanyl had no effect on MAC IE of sevoflurane.
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Affiliation(s)
- Lin He
- Department of Anaesthesiology, Children's Hospital of Fudan University, Shanghai, China
| | - Xuan Wang
- Department of Anaesthesiology, Children's Hospital of Fudan University, Shanghai, China
| | - Shan Zheng
- Department of Surgery, Children's Hospital of Fudan University, Shanghai, China
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Eagleman SL, Drover CM, Drover DR, Ouellette NT, MacIver MB. Remifentanil and Nitrous Oxide Anesthesia Produces a Unique Pattern of EEG Activity During Loss and Recovery of Response. Front Hum Neurosci 2018; 12:173. [PMID: 29867405 PMCID: PMC5950731 DOI: 10.3389/fnhum.2018.00173] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Accepted: 04/12/2018] [Indexed: 12/14/2022] Open
Abstract
Nitrous oxide (N2O) and remifentanil (remi) are used along with other anesthetic and adjuvant agents for routine surgical anesthesia, yet the electroencephalogram (EEG) changes produced by this combination are poorly described. N2O administered alone produces EEG spectral characteristics that are distinct from most hypnotics. Furthermore, EEG frequency-derived trends before and after clinically relevant time points vary depending on N2O concentration. Remifentanil typically increases low frequency and decreases high frequency activity in the EEG, but how it influences N2O's EEG effect is not known. Previous attempts to characterize EEG signals of patients anesthetized with N2O using frequency-derived measures have shown conflicts and inconsistencies. Thus, in addition to determining the spectral characteristics of this unique combination, we also test whether a newly proposed characterization of time-delayed embeddings of the EEG signal tracks loss and recovery of consciousness significantly at clinically relevant time points. We retrospectively investigated the effects of remi and N2O on EEG signals recorded from 32 surgical patients receiving anesthesia for elective abdominal surgeries. Remifentanil and N2O (66%) were co-administered during the procedures. Patients were tested for loss and recovery of response (ROR) to verbal stimuli after induction and upon cessation of anesthesia, respectively. We found that the addition of remifentanil to N2O anesthesia improves the ability of traditional frequency-derived measures, including the Bispectral Index (BIS), to discriminate between loss and ROR. Finally, we found that a novel analysis of EEG using nonlinear dynamics showed more significant differences between states than most spectral measures.
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Affiliation(s)
- Sarah L Eagleman
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University, Palo Alto, CA, United States
| | | | - David R Drover
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University, Palo Alto, CA, United States
| | - Nicholas T Ouellette
- Department of Civil and Environmental Engineering, Stanford University, Stanford, CA, United States
| | - M Bruce MacIver
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University, Palo Alto, CA, United States
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Choi BM. Characteristics of electroencephalogram signatures in sedated patients induced by various anesthetic agents. J Dent Anesth Pain Med 2017; 17:241-251. [PMID: 29349346 PMCID: PMC5766087 DOI: 10.17245/jdapm.2017.17.4.241] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 12/04/2017] [Accepted: 12/07/2017] [Indexed: 11/21/2022] Open
Abstract
Devices that monitor the depth of hypnosis based on the electroencephalogram (EEG) have long been commercialized, and clinicians use these to titrate the dosage of hypnotic agents. However, these have not yet been accepted as standard monitoring devices for anesthesiology. The primary reason is that the use of these monitoring devices does not completely prevent awareness during surgery, and the development of these devices has not taken into account the neurophysiological mechanisms of hypnotic agents, thus making it possible to show different levels of unconsciousness in the same brain status. An alternative is to monitor EEGs that are not signal processed with numerical values presented by these monitoring devices. Several studies have reported that power spectral analysis alone can distinguish the effects of different hypnotic agents on consciousness changes. This paper introduces the basic concept of power spectral analysis and introduces the EEG characteristics of various hypnotic agents that are used in sedation.
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Affiliation(s)
- Byung-Moon Choi
- Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
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25
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Kuhlmann L, Liley DTJ. Assessing nitrous oxide effect using electroencephalographically-based depth of anesthesia measures cortical state and cortical input. J Clin Monit Comput 2017; 32:173-188. [DOI: 10.1007/s10877-017-9978-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 01/02/2017] [Indexed: 12/19/2022]
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Mishra RK, Mahajan C, Prabhakar H, Kapoor I, Bithal PK. Effect of nitrous oxide on bispectral index values at equi-minimum alveolar concentrations of sevoflurane and desflurane. Indian J Anaesth 2017; 61:482-485. [PMID: 28655953 PMCID: PMC5474916 DOI: 10.4103/ija.ija_363_16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND AND AIMS Bispectral index (BIS) values may be anaesthetic agent-specific, depending on their ability to suppress the electroencephalogram (EEG) signals. We carried out a prospective, randomised clinical trial to study the effect of nitrous oxide (N2O) on the BIS values at an equi-minimum alveolar concentration (MAC) of sevoflurane and desflurane. METHODS Sixty adult patients undergoing spine surgery were randomised into two groups; Group S (sevoflurane; n = 30) and Group D (desflurane; n = 30) for the maintenance of anaesthesia in oxygen and air or oxygen and N2O mixture (FiO2-0.4) (Stage 1). BIS and fraction of inspired and end-tidal concentration of agents were noted at 1.0 MAC. In Stage 2, air or N2O was discontinued and the other carrier gas was introduced. At steady state of this carrier gas, values were again noted as in Stage 1. Statistical analysis was performed using two-way analysis of variance followed by Bonferroni correction, and Student's t-test for paired data. P<0.05 was considered statistically significant. RESULTS With air-oxygen as the carrier gas, sevoflurane and desflurane resulted in comparable BIS values (P = 0.44). With addition of 60% N2O, there was a significant increase in BIS values at 1.0 MAC for both the agents. Furthermore, higher BIS values were observed with sevoflurane compared to desflurane (P = 0.01). CONCLUSION Sevoflurane and desflurane at equi-MAC concentration exert similar effect on BIS values when used with air-oxygen. N2O results in higher BIS values; this effect is more pronounced in combination with sevoflurane.
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Affiliation(s)
- Rajeeb Kumar Mishra
- Department of Neuroanaesthesiology and Critical Care, All India Institute of Medical Sciences, New Delhi, India
| | - Charu Mahajan
- Department of Neuroanaesthesiology and Critical Care, All India Institute of Medical Sciences, New Delhi, India
| | - Hemanshu Prabhakar
- Department of Neuroanaesthesiology and Critical Care, All India Institute of Medical Sciences, New Delhi, India
| | - Indu Kapoor
- Department of Neuroanaesthesiology and Critical Care, All India Institute of Medical Sciences, New Delhi, India
| | - Parmod Kumar Bithal
- Department of Neuroanaesthesiology and Critical Care, All India Institute of Medical Sciences, New Delhi, India
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Kuhlmann L, Freestone DR, Manton JH, Heyse B, Vereecke HE, Lipping T, Struys MM, Liley DT. Neural mass model-based tracking of anesthetic brain states. Neuroimage 2016; 133:438-456. [DOI: 10.1016/j.neuroimage.2016.03.039] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 02/26/2016] [Accepted: 03/18/2016] [Indexed: 01/22/2023] Open
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Pavone KJ, Akeju O, Sampson AL, Ling K, Purdon PL, Brown EN. Nitrous oxide-induced slow and delta oscillations. Clin Neurophysiol 2016; 127:556-564. [PMID: 26118489 PMCID: PMC4675698 DOI: 10.1016/j.clinph.2015.06.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 06/02/2015] [Accepted: 06/03/2015] [Indexed: 01/24/2023]
Abstract
OBJECTIVES Switching from maintenance of general anesthesia with an ether anesthetic to maintenance with high-dose (concentration >50% and total gas flow rate >4 liters per minute) nitrous oxide is a common practice used to facilitate emergence from general anesthesia. The transition from the ether anesthetic to nitrous oxide is associated with a switch in the putative mechanisms and sites of anesthetic action. We investigated whether there is an electroencephalogram (EEG) marker of this transition. METHODS We retrospectively studied the ether anesthetic to nitrous oxide transition in 19 patients with EEG monitoring receiving general anesthesia using the ether anesthetic sevoflurane combined with oxygen and air. RESULTS Following the transition to nitrous oxide, the alpha (8-12 Hz) oscillations associated with sevoflurane dissipated within 3-12 min (median 6 min) and were replaced by highly coherent large-amplitude slow-delta (0.1-4 Hz) oscillations that persisted for 2-12 min (median 3 min). CONCLUSIONS Administration of high-dose nitrous oxide is associated with transient, large amplitude slow-delta oscillations. SIGNIFICANCE We postulate that these slow-delta oscillations may result from nitrous oxide-induced blockade of major excitatory inputs (NMDA glutamate projections) from the brainstem (parabrachial nucleus and medial pontine reticular formation) to the thalamus and cortex. This EEG signature of high-dose nitrous oxide may offer new insights into brain states during general anesthesia.
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Affiliation(s)
- Kara J Pavone
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Oluwaseun Akeju
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Anaesthesia, Harvard Medical School, Boston, MA, USA
| | - Aaron L Sampson
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Kelly Ling
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Patrick L Purdon
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Anaesthesia, Harvard Medical School, Boston, MA, USA
| | - Emery N Brown
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Anaesthesia, Harvard Medical School, Boston, MA, USA; Department of Brain and Cognitive Science, Massachusetts Institute of Technology, Cambridge, MA, USA; Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, USA; Institute for Medical Engineering and Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.
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Purdon PL, Sampson A, Pavone KJ, Brown EN. Clinical Electroencephalography for Anesthesiologists: Part I: Background and Basic Signatures. Anesthesiology 2015; 123:937-60. [PMID: 26275092 PMCID: PMC4573341 DOI: 10.1097/aln.0000000000000841] [Citation(s) in RCA: 460] [Impact Index Per Article: 51.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The widely used electroencephalogram-based indices for depth-of-anesthesia monitoring assume that the same index value defines the same level of unconsciousness for all anesthetics. In contrast, we show that different anesthetics act at different molecular targets and neural circuits to produce distinct brain states that are readily visible in the electroencephalogram. We present a two-part review to educate anesthesiologists on use of the unprocessed electroencephalogram and its spectrogram to track the brain states of patients receiving anesthesia care. Here in part I, we review the biophysics of the electroencephalogram and the neurophysiology of the electroencephalogram signatures of three intravenous anesthetics: propofol, dexmedetomidine, and ketamine, and four inhaled anesthetics: sevoflurane, isoflurane, desflurane, and nitrous oxide. Later in part II, we discuss patient management using these electroencephalogram signatures. Use of these electroencephalogram signatures suggests a neurophysiologically based paradigm for brain state monitoring of patients receiving anesthesia care.
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Affiliation(s)
- Patrick L. Purdon
- Associate Bioengineer, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts; Assistant Professor of Anaesthesia, Department of Anesthesia, Harvard Medical School, Boston, Massachusetts
| | - Aaron Sampson
- Research Assistant, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Kara J. Pavone
- Research Assistant, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts
| | - Emery N. Brown
- Anesthetist, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts; Warren M. Zapol Professor of Anesthesia, Department of Anesthesia, Harvard Medical School, Boston, Massachusetts; Edward Hood Taplin Professor of Medical Engineering, Institute for Medical Engineering and Science and Harvard-Massachusetts Institute of Technology, Health Sciences and Technology Program, Professor of Computational Neuroscience, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
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Hight DF, Dadok VM, Szeri AJ, García PS, Voss L, Sleigh JW. Emergence from general anesthesia and the sleep-manifold. Front Syst Neurosci 2014; 8:146. [PMID: 25165436 PMCID: PMC4131673 DOI: 10.3389/fnsys.2014.00146] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 07/24/2014] [Indexed: 12/17/2022] Open
Abstract
The electroencephalogram (EEG) during the re-establishment of consciousness after general anesthesia and surgery varies starkly between patients. Can the EEG during this emergence period provide a means of estimating the underlying biological processes underpinning the return of consciousness? Can we use a model to infer these biological processes from the EEG patterns? A frontal EEG was recorded from 84 patients. Ten patients were chosen for state-space analysis. Five showed archetypal emergences; which consisted of a progressive decrease in alpha power and increase peak alpha frequency before return of responsiveness. The five non-archetypal emergences showed almost no spectral EEG changes (even as the volatile general anesthetic decreased) and then an abrupt return of responsiveness. We used Bayesian methods to estimate the likelihood of an EEG pattern corresponding to the position of the patient on a 2-dimensional manifold in a state space of excitatory connection strength vs. change in intrinsic resting neuronal membrane conductivity. We could thus visualize the trajectory of each patient in the state-space during their emergence period. The patients who followed an archetypal emergence displayed a very consistent pattern; consisting of progressive increase in conductivity, and a temporary period of increased connection strength before return of responsiveness. The non-archetypal emergence trajectories remained fixed in a region of phase space characterized by a relatively high conductivity and low connection strength throughout emergence. This unexpected progressive increase in conductivity during archetypal emergence may be due to an abating of the surgical stimulus during this period. Periods of high connection strength could represent forays into dissociated consciousness, but the model suggests all patients reposition near the fold in the state space to take advantage of bi-stable cortical dynamics before transitioning to consciousness.
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Affiliation(s)
- Darren F Hight
- Department of Anaesthesiology, Waikato Clinical School, University of Auckland Hamilton, New Zealand
| | - Vera M Dadok
- Department of Mechanical Engineering and Center for Neural Engineering and Prostheses, University of California Berkeley, CA, USA
| | - Andrew J Szeri
- Department of Mechanical Engineering and Center for Neural Engineering and Prostheses, University of California Berkeley, CA, USA
| | - Paul S García
- Department of Anesthesiology, Atlanta VA Medical Center/Emory University Atlanta, GA, USA
| | - Logan Voss
- Department of Anaesthesiology, Waikato Clinical School, University of Auckland Hamilton, New Zealand
| | - Jamie W Sleigh
- Department of Anaesthesiology, Waikato Clinical School, University of Auckland Hamilton, New Zealand
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Servin F, Billard V. IV. Surrogate measures, do they really describe anaesthetic state? Br J Anaesth 2014; 112:787-90. [DOI: 10.1093/bja/aeu006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Ching S, Brown EN. Modeling the dynamical effects of anesthesia on brain circuits. Curr Opin Neurobiol 2014; 25:116-22. [PMID: 24457211 DOI: 10.1016/j.conb.2013.12.011] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 12/14/2013] [Accepted: 12/18/2013] [Indexed: 11/28/2022]
Abstract
General anesthesia is a neurophysiological state that consists of unconsciousness, amnesia, analgesia, and immobility along with maintenance of physiological stability. General anesthesia has been used in the United States for more than 167 years. Now, using systems neuroscience paradigms how anesthetics act in the brain and central nervous system to create the states of general anesthesia is being understood. Propofol is one of the most widely used and the most widely studied anesthetics. When administered for general anesthesia or sedation, the electroencephalogram (EEG) under propofol shows highly structured, rhythmic activity that is strongly associated with changes in the patient's level of arousal. These highly structured oscillations lend themselves readily to mathematical descriptions using dynamical systems models. We review recent model descriptions of the commonly observed EEG patterns associated with propofol: paradoxical excitation, strong frontal alpha oscillations, anteriorization and burst suppression. Our analysis suggests that propofol's actions at GABAergic networks in the cortex, thalamus and brainstem induce profound brain dynamics that are one of the likely mechanisms through which this anesthetic induces altered arousal states from sedation to unconsciousness. Because these dynamical effects are readily observed in the EEG, the mathematical descriptions of how propofol's EEG signatures relate to its mechanisms of action in neural circuits provide anesthesiologists with a neurophysiologically based approach to monitoring the brain states of patients receiving anesthesia care.
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Affiliation(s)
- Shinung Ching
- Department of Electrical & Systems Engineering, Division of Biology & Biomedical Sciences, Washington University in St. Louis, St. Louis, MO 63130, United States
| | - Emery N Brown
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital/Harvard Medical School, Boston, MA 02114, United States; Institute for Medical Engineering and Science, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
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The perioperative use of nitrous oxide: renaissance of an old gas or funeral of an ancient relict? Curr Opin Anaesthesiol 2013; 26:354-60. [PMID: 23426038 DOI: 10.1097/aco.0b013e32835f8151] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Conflicting reports about adverse events following nitrous oxide (N(2)O) application have spurred a discussion whether N(2)O should be abandoned from clinical practice. Concurrently, N(2)O is increasingly used as a single anesthetic agent in medical procedures. This article reviews and discusses reports about the present use of N(2)O. RECENT FINDINGS Multiple publications demonstrate an increasing use of N(2)O as a procedural analgesic and sedative. Results from the Evaluation of Nitrous Oxide in the Gas Mixture for Anesthesia trial have been contrasted by recent studies reporting no increased risk for perioperative complications, particularly related to the cardiovascular and cerebrovascular system. Recent studies show that electroencephalogram-based anesthesia depth monitoring is not compatible with the use of N(2)O because of its distinct influence on electroencephalogram wave patterns. The clinical relevance of the proposed neurotoxicity, immunosuppression and influence on methionine metabolism remains unclear. Recently, its acute and long-term analgesic potency has been proven. Occupational exposure might pose a relevant health hazard. SUMMARY Based on the present literature, abolishment of N(2)O is controversial. When avoided in patients at risk for adverse events, N(2)O is still a valuable supplement to general anesthesia and a potent procedural analgesic drug. In the latter, its use by nonanesthesiologists should be discouraged.
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Kuhlmann L, Foster BL, Liley DTJ. Modulation of functional EEG networks by the NMDA antagonist nitrous oxide. PLoS One 2013; 8:e56434. [PMID: 23457568 PMCID: PMC3572968 DOI: 10.1371/journal.pone.0056434] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 01/11/2013] [Indexed: 11/22/2022] Open
Abstract
Parietal networks are hypothesised to play a central role in the cortical information synthesis that supports conscious experience and behavior. Significant reductions in parietal level functional connectivity have been shown to occur during general anesthesia with propofol and a range of other GABAergic general anesthetic agents. Using two analysis approaches (1) a graph theoretic analysis based on surrogate-corrected zero-lag correlations of scalp EEG, and (2) a global coherence analysis based on the EEG cross-spectrum, we reveal that sedation with the NMDA receptor antagonist nitrous oxide (N2O), an agent that has quite different electroencephalographic effects compared to the inductive general anesthetics, also causes significant alterations in parietal level functional networks, as well as changes in full brain and frontal level networks. A total of 20 subjects underwent N2O inhalation at either 20%, 40% or 60% peak N2O/O2 gas concentration levels. N2O-induced reductions in parietal network level functional connectivity (on the order of 50%) were exclusively detected by utilising a surface Laplacian derivation, suggesting that superficial, smaller spatial scale, cortical networks were most affected. In contrast reductions in frontal network functional connectivity were optimally discriminated using a common-reference derivation (reductions on the order of 10%), indicating that the NMDA antagonist N2O induces spatially coherent and widespread perturbations in frontal activity. Our findings not only give important weight to the idea of agent invariant final network changes underlying drug-induced reductions in consciousness, but also provide significant impetus for the application and development of multiscale functional analyses to systematically characterise the network level cortical effects of NMDA receptor related hypofunction. Future work at the source space level will be needed to verify the consistency between cortical network changes seen at the source level and those presented here at the EEG sensor space level.
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Affiliation(s)
- Levin Kuhlmann
- Brain and Psychological Sciences Research Centre, Swinburne University of Technology, Hawthorn, Victoria, Australia
| | - Brett L. Foster
- Department of Neurology and Neurological Sciences, School of Medicine, Stanford University, Stanford, California , United States of America
| | - David T. J. Liley
- Brain and Psychological Sciences Research Centre, Swinburne University of Technology, Hawthorn, Victoria, Australia
- * E-mail:
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Foster BL, Liley DT. Effects of nitrous oxide sedation on resting electroencephalogram topography. Clin Neurophysiol 2013; 124:417-23. [DOI: 10.1016/j.clinph.2012.08.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2012] [Revised: 08/10/2012] [Accepted: 08/14/2012] [Indexed: 11/30/2022]
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Dynamical changes in neurological diseases and anesthesia. Curr Opin Neurobiol 2012; 22:693-703. [PMID: 22446010 DOI: 10.1016/j.conb.2012.02.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 02/11/2012] [Accepted: 02/19/2012] [Indexed: 12/22/2022]
Abstract
Dynamics of neuronal networks can be altered in at least two ways: by changes in connectivity, that is, the physical architecture of the network, or changes in the amplitudes and kinetics of the intrinsic and synaptic currents within and between the elements making up a network. We argue that the latter changes are often overlooked as sources of alterations in network behavior when there are also structural (connectivity) abnormalities present; indeed, they may even give rise to the structural changes observed in these states. Here we look at two clinically relevant states (Parkinson's disease and schizophrenia) and argue that non-structural changes are important in the development of abnormal dynamics within the networks known to be relevant to each disorder. We also discuss anesthesia, since it is entirely acute, thus illustrating the potent effects of changes in synaptic and intrinsic membrane currents in the absence of structural alteration. In each of these, we focus on the role of changes in GABAergic function within microcircuits, stressing literature within the last few years.
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