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Martin JC, Liley DTJ, Beer CFLA, Davidson AJ. Topographical Features of Pediatric Electroencephalography during High Initial Concentration Sevoflurane for Inhalational Induction of Anesthesia. Anesthesiology 2024; 140:890-905. [PMID: 38207324 DOI: 10.1097/aln.0000000000004902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2024]
Abstract
BACKGROUND High-density electroencephalographic (EEG) monitoring remains underutilized in clinical anesthesia, despite its obvious utility in unraveling the profound physiologic impact of these agents on central nervous system functioning. In school-aged children, the routine practice of rapid induction with high concentrations of inspiratory sevoflurane is commonplace, given its favorable efficacy and tolerance profile. However, few studies investigate topographic EEG during the critical timepoint coinciding with loss of responsiveness-a key moment for anesthesiologists in their everyday practice. The authors hypothesized that high initial sevoflurane inhalation would better precipitate changes in brain regions due to inhomogeneities in maturation across three different age groups compared with gradual stepwise paradigms utilized by other investigators. Knowledge of these changes may inform strategies for agent titration in everyday clinical settings. METHODS A total of 37 healthy children aged 5 to 10 yr underwent induction with 4% or greater sevoflurane in high-flow oxygen. Perturbations in anesthetic state were investigated in 23 of these children using 64-channel EEG with the Hjorth Laplacian referencing scheme. Topographical maps illustrated absolute, relative, and total band power across three age groups: 5 to 6 yr (n = 7), 7 to 8 yr (n = 8), and 9 to 10 yr (n = 8). RESULTS Spectral analysis revealed a large shift in total power driven by increased delta oscillations. Well-described topographic patterns of anesthesia, e.g., frontal predominance, paradoxical beta excitation, and increased slow activity, were evident in the topographic maps. However, there were no statistically significant age-related changes in spectral power observed in a midline electrode subset between the groups when responsiveness was lost compared to the resting state. CONCLUSIONS High initial concentration sevoflurane induction causes large-scale topographic effects on the pediatric EEG. Within the minute after unresponsiveness, this dosage may perturb EEG activity in children to an extent where age-related differences are not discernible. EDITOR’S PERSPECTIVE
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Affiliation(s)
| | - David T J Liley
- Department of Medicine, University of Melbourne, Melbourne, Australia
| | - Christopher F L A Beer
- Swinburne University of Technology, Faculty of Science, Engineering, and Technology, Australia
| | - Andrew J Davidson
- Department of Anaesthetics, Murdoch Children's Research Institute, Victoria, Australia; Department of Paediatrics, University of Melbourne, Melbourne, Australia
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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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Dai R, Huang Z, Larkin TE, Tarnal V, Picton P, Vlisides PE, Janke E, McKinney A, Hudetz AG, Harris RE, Mashour GA. Psychedelic concentrations of nitrous oxide reduce functional differentiation in frontoparietal and somatomotor cortical networks. Commun Biol 2023; 6:1284. [PMID: 38114805 PMCID: PMC10730842 DOI: 10.1038/s42003-023-05678-1] [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: 04/26/2023] [Accepted: 12/05/2023] [Indexed: 12/21/2023] Open
Abstract
Despite the longstanding use of nitrous oxide and descriptions of its psychological effects more than a century ago, there is a paucity of neurobiological investigation of associated psychedelic experiences. We measure the brain's functional geometry (through analysis of cortical gradients) and temporal dynamics (through analysis of co-activation patterns) using human resting-state functional magnetic resonance imaging data acquired before and during administration of 35% nitrous oxide. Both analyses demonstrate that nitrous oxide reduces functional differentiation in frontoparietal and somatomotor networks. Importantly, the subjective psychedelic experience induced by nitrous oxide is inversely correlated with the degree of functional differentiation. Thus, like classical psychedelics acting on serotonin receptors, nitrous oxide flattens the functional geometry of the cortex and disrupts temporal dynamics in association with psychoactive effects.
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Affiliation(s)
- Rui Dai
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Zirui Huang
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.
- Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.
- Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, 48109, USA.
| | - Tony E Larkin
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Chronic Pain and Fatigue Research Center, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Vijay Tarnal
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Paul Picton
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Phillip E Vlisides
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Ellen Janke
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Amy McKinney
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Anthony G Hudetz
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Richard E Harris
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, 48109, USA
- Chronic Pain and Fatigue Research Center, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - George A Mashour
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
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Palanca BJA, Conway CR, Zeffiro T, Gott BM, Nguyen T, Janski A, Jain N, Komen H, Burke BA, Zorumski CF, Nagele P. Persistent Brain Connectivity Changes in Healthy Volunteers Following Nitrous Oxide Inhalation. BIOLOGICAL PSYCHIATRY GLOBAL OPEN SCIENCE 2023; 3:698-704. [PMID: 37881568 PMCID: PMC10593877 DOI: 10.1016/j.bpsgos.2023.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Revised: 01/15/2022] [Accepted: 01/23/2023] [Indexed: 02/05/2023] Open
Abstract
Background Nitrous oxide holds promise in the treatment of major depressive disorder. Its psychotropic effects and NMDA receptor antagonism have led to comparisons with ketamine. Despite longstanding use, persistent effects of nitrous oxide on the brain have not been characterized. Methods Sixteen healthy volunteers were recruited in a double-blind crossover study. In randomized order, individuals underwent a 1-hour inhalation of either 50% nitrous oxide/oxygen or air/oxygen mixtures. At least two 7.5-minute echo-planar resting-state functional magnetic resonance imaging scans were obtained before and at 2 and 24 hours after each inhalation (average 130 min/participant). Using the time series of preprocessed, motion artifact-scrubbed, and nuisance covariate-regressed imaging data, interregional signal correlations were measured and converted to T scores. Hierarchical clustering and linear mixed-effects models were employed. Results Nitrous oxide inhalation produced changes in global brain connectivity that persisted in the occipital cortex at 2 and 24 hours postinhalation (p < .05, false discovery rate-corrected). Analysis of resting-state networks demonstrated robust strengthening of connectivity between regions of the visual network and those of the dorsal attention network, across 2 and 24 hours after inhalation (p < .05, false discovery rate-corrected). Weaker changes in connectivity were found between the visual cortex and regions of the frontoparietal and default mode networks. Parallel analyses following air/oxygen inhalation yielded no significant changes in functional connectivity. Conclusions Nitrous oxide inhalation in healthy volunteers revealed persistent increases in global connectivity between regions of primary visual cortex and dorsal attention network. These findings suggest that nitrous oxide inhalation induces neurophysiological cortical changes that persist for at least 24 hours.
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Affiliation(s)
- Ben Julian A. Palanca
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri
- Department of Psychiatry and Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine in St. Louis, St. Louis, Missouri
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri
- Division of Biology and Biomedical Sciences, Washington University School of Medicine in St. Louis, St. Louis, Missouri
- Neuroimaging Labs Research Center, Washington University School of Medicine in St. Louis, St. Louis, Missouri
- Center on Biological Rhythms and Sleep, Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Charles R. Conway
- Department of Psychiatry and Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine in St. Louis, St. Louis, Missouri
- Neuroimaging Labs Research Center, Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Thomas Zeffiro
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Britt M. Gott
- Department of Psychiatry and Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine in St. Louis, St. Louis, Missouri
- Neuroimaging Labs Research Center, Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Thomas Nguyen
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Alvin Janski
- Department of Psychiatry and Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Nisha Jain
- Department of Anesthesia and Critical Care, University of Chicago Medicine, Chicago, Illinois
| | - Helga Komen
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Broc A. Burke
- Department of Anesthesiology, University of Colorado School of Medicine, Aurora, Colorado
| | - Charles F. Zorumski
- Department of Psychiatry and Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Peter Nagele
- Department of Anesthesia and Critical Care, University of Chicago Medicine, Chicago, Illinois
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Dai R, Larkin TE, Huang Z, Tarnal V, Picton P, Vlisides PE, Janke E, McKinney A, Hudetz AG, Harris RE, Mashour GA. Classical and non-classical psychedelic drugs induce common network changes in human cortex. Neuroimage 2023; 273:120097. [PMID: 37031827 DOI: 10.1016/j.neuroimage.2023.120097] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 03/06/2023] [Accepted: 04/06/2023] [Indexed: 04/11/2023] Open
Abstract
The neurobiology of the psychedelic experience is not fully understood. Identifying common brain network changes induced by both classical (i.e., acting at the 5-HT2 receptor) and non-classical psychedelics would provide mechanistic insight into state-specific characteristics. We analyzed whole-brain functional connectivity based on resting-state fMRI data in humans, acquired before and during the administration of nitrous oxide, ketamine, and lysergic acid diethylamide. We report that, despite distinct molecular mechanisms and modes of delivery, all three psychedelics reduced within-network functional connectivity and enhanced between-network functional connectivity. More specifically, all three drugs increased connectivity between right temporoparietal junction and bilateral intraparietal sulcus as well as between precuneus and left intraparietal sulcus. These regions fall within the posterior cortical "hot zone," posited to mediate the qualitative aspects of experience. Thus, both classical and non-classical psychedelics modulate networks within an area of known relevance for consciousness, identifying a biologically plausible candidate for their subjective effects.
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Affiliation(s)
- Rui Dai
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Tony E Larkin
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Chronic Pain and Fatigue Research Center, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Zirui Huang
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Vijay Tarnal
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Paul Picton
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Phillip E Vlisides
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Ellen Janke
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Amy McKinney
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Anthony G Hudetz
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, United States
| | - Richard E Harris
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Chronic Pain and Fatigue Research Center, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, United States.
| | - George A Mashour
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Michigan Psychedelic Center, University of Michigan Medical School, Ann Arbor, MI 48109, United States; Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, United States; Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, United States.
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Quach DF, de Leon VC, Conway CR. Nitrous Oxide: an emerging novel treatment for treatment-resistant depression. J Neurol Sci 2021; 434:120092. [PMID: 34953347 DOI: 10.1016/j.jns.2021.120092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 12/03/2021] [Accepted: 12/12/2021] [Indexed: 10/19/2022]
Abstract
Stemming from the results of the historic STAR-D trial, it is evident that a significant subset of individuals (20-25%) with major depressive disorder (MDD) do not respond to conventional antidepressant medications. As a result, an emphasis has been placed on the development of novel therapeutics for MDD over the last two decades. Recently, substantial research efforts have been focused on the use of ketamine as an antidepressant whose mechanism of action is via the N-methyl-d-aspartate (NMDA) receptor. Another potential therapeutic compound of interest is nitrous oxide, which has been utilized for more than a century in multiple fields of medicine for its analgesic and anesthetic properties. Recent clinical studies suggest that nitrous oxide may be effective for treatment-resistant depression. In this review, we will discuss the administration of nitrous oxide as a psychiatric intervention, current use in psychiatry, putative mechanisms of action, and future directions highlighting knowledge gaps and other potential utilities in the field of psychiatry.
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Affiliation(s)
- Darin F Quach
- Department of Psychiatry, Washington University School of Medicine, Saint Louis, MO, United States of America
| | - Victoria C de Leon
- Department of Psychiatry, Washington University School of Medicine, Saint Louis, MO, United States of America
| | - Charles R Conway
- Department of Psychiatry, Washington University School of Medicine, Saint Louis, MO, United States of America.
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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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Kohtala S, Rantamäki T. Rapid-acting antidepressants and the regulation of TrkB neurotrophic signalling-Insights from ketamine, nitrous oxide, seizures and anaesthesia. Basic Clin Pharmacol Toxicol 2021; 129:95-103. [PMID: 33973360 DOI: 10.1111/bcpt.13598] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 05/03/2021] [Accepted: 05/04/2021] [Indexed: 01/18/2023]
Abstract
Increased glutamatergic neurotransmission and synaptic plasticity in the prefrontal cortex have been associated with the rapid antidepressant effects of ketamine. Activation of BDNF (brain-derived neurotrophic factor) receptor TrkB is considered a key molecular event for antidepressant-induced functional and structural synaptic plasticity. Several mechanisms have been proposed to underlie ketamine's effects on TrkB, but much remains unclear. Notably, preliminary studies suggest that besides ketamine, nitrous oxide (N2 O) can rapidly alleviate depressive symptoms. We have shown nitrous oxide to evoke TrkB signalling preferentially after the acute pharmacological effects have dissipated (ie after receptor disengagement), when slow delta frequency electroencephalogram (EEG) activity is up-regulated. Our findings also demonstrate that various anaesthetics and sedatives activate TrkB signalling, further highlighting the complex mechanisms underlying TrkB activation. We hypothesize that rapid-acting antidepressants share the ability to regulate TrkB signalling during homeostatically evoked slow-wave activity and that this mechanism is important for sustained antidepressant effects. Our observations urge the examination of rapid and sustained antidepressant effects beyond conventional receptor pharmacology by focusing on brain physiology and temporally distributed signalling patterns spanning both wake and sleep. Potential implications of this approach for the improvement of current therapies and discovery of novel antidepressants are discussed.
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Affiliation(s)
- Samuel Kohtala
- Department of Psychiatry, Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA.,Laboratory of Neurotherapeutics, Drug Research Program, Division of Pharmacology and Pharmacotherapy, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland.,SleepWell Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Tomi Rantamäki
- Laboratory of Neurotherapeutics, Drug Research Program, Division of Pharmacology and Pharmacotherapy, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland.,SleepWell Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
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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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10
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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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Kalmoe MC, Janski AM, Zorumski CF, Nagele P, Palanca BJ, Conway CR. Ketamine and nitrous oxide: The evolution of NMDA receptor antagonists as antidepressant agents. J Neurol Sci 2020; 412:116778. [PMID: 32240970 DOI: 10.1016/j.jns.2020.116778] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 02/20/2020] [Accepted: 03/14/2020] [Indexed: 12/19/2022]
Abstract
N-methyl-d-aspartate receptor (NMDAR) antagonists, including ketamine and nitrous oxide, are currently intensely studied as rapid-acting antidepressant agents. Interestingly, both of these compounds are also drugs of abuse. Intravenous ketamine, a dissociative anesthetic that induces complex downstream effects via NMDARs, rapidly reduces depressive and suicidal symptoms in treatment-resistant depression (TRD), as demonstrated by several trials. Recently, the United States Food and Drug Administration (FDA) approved an intranasal version of ketamine (esketamine) for TRD. The United States Drug Enforcement Agency (DEA) lists ketamine as a Class III scheduled drug (moderate-low potential for physical and psychological abuse). The FDA has established a Risk Evaluation and Management Strategy (REMS) program to ensure proper drug storage, handling, dispensing, and monitoring intranasal esketamine to minimize misuse/abuse opportunities. Nitrous Oxide is a colorless, odorless, gas that has been in medical use for over 150 years. The mechanisms of action of nitrous oxide are not fully understood; however, it is known to act as a non-competitive inhibitor of NMDA-type glutamate receptors. Currently, nitrous oxide is used for inhalational general anesthesia and analgesia for short procedures. Inhaled nitrous oxide is also used recreationally, primarily by teens and young adults, but is not believed to have strong addiction potential. In contrast to ketamine, nitrous oxide is not a controlled substance and can be legally purchased without a prescription. A recent double-blind, prospective, cross-over study demonstrated that nitrous oxide reduced depressive symptoms in a group of severely ill TRD patients. Though this is a promising initial study, further investigation is needed.
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Affiliation(s)
- Molly C Kalmoe
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, United States of America
| | - Alvin M Janski
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, United States of America
| | - Charles F Zorumski
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, United States of America
| | - Peter Nagele
- Department of Anesthesia and Critical Care, The University of Chicago Medical Center, Chicago, IL, United States of America
| | - Ben J Palanca
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, United States of America
| | - Charles R Conway
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, United States of America.
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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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Zafirova Z, Sheehan C, Hosseinian L. Update on nitrous oxide and its use in anesthesia practice. Best Pract Res Clin Anaesthesiol 2018; 32:113-123. [DOI: 10.1016/j.bpa.2018.06.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 06/22/2018] [Indexed: 01/22/2023]
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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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Pelentritou A, Kuhlmann L, Cormack J, Woods W, Sleigh J, Liley D. Recording Brain Electromagnetic Activity During the Administration of the Gaseous Anesthetic Agents Xenon and Nitrous Oxide in Healthy Volunteers. J Vis Exp 2018. [PMID: 29364232 DOI: 10.3791/56881] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Anesthesia arguably provides one of the only systematic ways to study the neural correlates of global consciousness/unconsciousness. However to date most neuroimaging or neurophysiological investigations in humans have been confined to the study of γ-Amino-Butyric-Acid-(GABA)-receptor-agonist-based anesthetics, while the effects of dissociative N-Methyl-D-Aspartate-(NMDA)-receptor-antagonist-based anesthetics ketamine, nitrous oxide (N2O) and xenon (Xe) are largely unknown. This paper describes the methods underlying the simultaneous recording of magnetoencephalography (MEG) and electroencephalography (EEG) from healthy males during inhalation of the gaseous anesthetic agents N2O and Xe. Combining MEG and EEG data enables the assessment of electromagnetic brain activity during anesthesia at high temporal, and moderate spatial, resolution. Here we describe a detailed protocol, refined over multiple recording sessions, that includes subject recruitment, anesthesia equipment setup in the MEG scanner room, data collection and basic data analysis. In this protocol each participant is exposed to varying levels of Xe and N2O in a repeated measures cross-over design. Following relevant baseline recordings participants are exposed to step-wise increasing inspired concentrations of Xe and N2O of 8, 16, 24 and 42%, and 16, 32 and 47% respectively, during which their level of responsiveness is tracked with an auditory continuous performance task (aCPT). Results are presented for a number of recordings to highlight the sensor-level properties of the raw data, the spectral topography, the minimization of head movements, and the unequivocal level dependent effects on the auditory evoked responses. This paradigm describes a general approach to the recording of electromagnetic signals associated with the action of different kinds of gaseous anesthetics, which can be readily adapted to be used with volatile and intravenous anesthetic agents. It is expected that the method outlined can contribute to the understanding of the macro-scale mechanisms of anesthesia by enabling methodological extensions involving source space imaging and functional network analysis.
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Affiliation(s)
| | - Levin Kuhlmann
- Centre for Human Psychopharmacology, Swinburne University of Technology
| | - John Cormack
- Department of Anaesthesia and Pain Management, St. Vincent's Hospital Melbourne
| | - Will Woods
- Brain and Psychological Science Research Centre, Swinburne University of Technology
| | - Jamie Sleigh
- Department of Anaesthesiology, University of Auckland
| | - David Liley
- Centre for Human Psychopharmacology, Swinburne University of Technology;
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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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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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Zorumski CF, Nagele P, Mennerick S, Conway CR. Treatment-Resistant Major Depression: Rationale for NMDA Receptors as Targets and Nitrous Oxide as Therapy. Front Psychiatry 2015; 6:172. [PMID: 26696909 PMCID: PMC4673867 DOI: 10.3389/fpsyt.2015.00172] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 11/23/2015] [Indexed: 11/13/2022] Open
Abstract
Major depressive disorder (MDD) remains a huge personal and societal encumbrance. Particularly burdensome is a virulent subtype of MDD, treatment resistant major depression (TMRD), which afflicts 15-30% of MDD patients. There has been recent interest in N-methyl-d-aspartate receptors (NMDARs) as targets for treatment of MDD and perhaps TMRD. To date, most pre-clinical and clinical studies have focused on ketamine, although psychotomimetic and other side effects may limit ketamine's utility. These considerations prompted a recent promising pilot clinical trial of nitrous oxide, an NMDAR antagonist that acts through a mechanism distinct from that of ketamine, in patients with severe TRMD. In this paper, we review the clinical picture of TRMD as a subtype of MDD, the evolution of ketamine as a fast-acting antidepressant, and clinical and basic science studies supporting the possible use of nitrous oxide as a rapid antidepressant.
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Affiliation(s)
- Charles F Zorumski
- Department of Psychiatry, Washington University School of Medicine , St. Louis, MO , USA ; Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine , St. Louis, MO , USA
| | - Peter Nagele
- Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine , St. Louis, MO , USA ; Department of Anesthesiology, Washington University School of Medicine , St. Louis, MO , USA
| | - Steven Mennerick
- Department of Psychiatry, Washington University School of Medicine , St. Louis, MO , USA ; Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine , St. Louis, MO , USA
| | - Charles R Conway
- Department of Psychiatry, Washington University School of Medicine , St. Louis, MO , USA ; Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine , St. Louis, MO , USA
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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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