1
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Kaplan T, Keskin UE, Kapan ÖF, Han S. Editorial comment: correlation between postoperative cognitive dysfunction and the extent of lung resection in lung cancer patients. Eur J Cardiothorac Surg 2023; 64:ezad356. [PMID: 37889233 DOI: 10.1093/ejcts/ezad356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 10/26/2023] [Indexed: 10/28/2023] Open
Affiliation(s)
- Tevfik Kaplan
- Thoracic Surgery Clinic, Ankara Etlik City Hospital, Ankara, Turkey
| | - Ufuk Emre Keskin
- Thoracic Surgery Clinic, Ankara Etlik City Hospital, Ankara, Turkey
| | - Ömer Faruk Kapan
- Thoracic Surgery Clinic, Ankara Etlik City Hospital, Ankara, Turkey
| | - Serdar Han
- Thoracic Surgery Clinic, Ankara Etlik City Hospital, Ankara, Turkey
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2
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Joys S, Panda NB, Ahuja CK, Luthra A, Tripathi M, Mahajan S, Kaloria N, Jain C, Singh N, Regmi S, Jangra K, Chauhan R, Soni SL, Bhagat H. Comparison of Effects of Propofol and Sevoflurane on the Cerebral Vasculature Assessed by Digital Subtraction Angiographic Parameters in Patients Treated for Ruptured Cerebral Aneurysm: A Preliminary Study. J Neurosurg Anesthesiol 2023; 35:327-332. [PMID: 35090162 DOI: 10.1097/ana.0000000000000833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 12/17/2021] [Indexed: 11/25/2022]
Abstract
BACKGROUND Studies have evaluated the effects of volatile and intravenous anesthetic agents on the cerebral vasculature with inconsistent results. We used digital subtraction angiography to compare the effects of propofol and sevoflurane on the luminal diameter of cerebral vessels and on cerebral transit time in patients with aneurysmal subarachnoid hemorrhage (aSAH). METHODS This prospective preliminary study included adult patients with good-grade aSAH scheduled for endovascular coil embolization; patients were randomized to receive propofol or sevoflurane anesthesia during endovascular coiling. The primary outcome was the luminal diameter of 7 cerebral vessel segments measured on the diseased and nondiseased sides of the brain at 3 time points: awake, postinduction of anesthesia, and postcoiling. Cerebral transit time was also measured as a surrogate for cerebral blood flow. RESULTS Eighteen patients were included in the analysis (9 per group). Baseline and intraoperative parameters were similar between the groups. Propofol increased the diameter of 1 vessel segment at postinduction and postcoiling on the diseased side and in 1 segment at postcoiling on the nondiseased side of the brain ( P <0.05). Sevoflurane increased vessel diameter in 3 segments at postinduction and in 2 segments at postcoiling on the diseased side, and in 4 segments at postcoiling on the nondiseased side ( P <0.05). Cerebral transit time did not change compared with baseline awake state in either group and was not different between the groups. CONCLUSIONS Sevoflurane has cerebral vasodilating properties compared with propofol in patients with good-grade aSAH. However, sevoflurane affects cerebral transit time comparably to propofol.
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Affiliation(s)
- Steve Joys
- Departments of Anaesthesia and Intensive Care
| | | | | | | | - Manjul Tripathi
- Neurosurgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | | | | | | | - Nidhi Singh
- Departments of Anaesthesia and Intensive Care
| | | | | | | | - Shiv L Soni
- Departments of Anaesthesia and Intensive Care
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3
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Vedaei F, Alizadeh M, Tantawi M, Romo V, Mohamed FB, Wu C. Vascular and neuronal effects of general anesthesia on the brain: An fMRI study. J Neuroimaging 2023; 33:109-120. [PMID: 36097249 DOI: 10.1111/jon.13049] [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: 07/22/2022] [Revised: 08/30/2022] [Accepted: 08/30/2022] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND AND PURPOSE A number of functional magnetic resonance imaging (fMRI) studies rely on application of anesthetic agents during scanning that can modulate and complicate interpretation of the measured hemodynamic blood oxygenation level-dependent (BOLD) response. The purpose of the present study was to investigate the effect of general anesthesia on two main components of BOLD signal including neuronal activity and vascular response. METHODS Breath-holding (BH) fMRI was conducted in wakefulness and under anesthesia states in 9 patients with drug-resistant epilepsy who needed to get scanned under anesthesia during laser interstitial thermal therapy. BOLD and BOLD cerebrovascular reactivity (BOLD-CVR) maps were compared using t-test between two states to assess the effect of anesthesia on neuronal activity and vascular factors (p < .05). RESULTS Overall, our findings revealed an increase in BOLD-CVR and decrease in BOLD response under anesthesia in several brain regions. The results proposed that the modulatory mechanism of anesthetics on neuronal and vascular components of BOLD signal may work in different ways. CONCLUSION This experiment for the first human study showed that anesthesia may play an important role in dissociation between neuronal and vascular responses contributed to hemodynamic BOLD signal using BH fMRI imaging that may assist the implication of general anesthesia and interpretation of outcomes in clinical setting.
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Affiliation(s)
- Faezeh Vedaei
- Jefferson Integrated Magnetic Resonance Imaging Center, Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Mahdi Alizadeh
- Jefferson Integrated Magnetic Resonance Imaging Center, Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.,Department of Neurological Surgery, Vickie and Jack Farber Institute for Neuroscience, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Mohamed Tantawi
- Jefferson Integrated Magnetic Resonance Imaging Center, Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Victor Romo
- Department of Anesthesiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Feroze B Mohamed
- Jefferson Integrated Magnetic Resonance Imaging Center, Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Chengyuan Wu
- Jefferson Integrated Magnetic Resonance Imaging Center, Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.,Department of Neurological Surgery, Vickie and Jack Farber Institute for Neuroscience, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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4
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Xu M, Bo B, Pei M, Chen Y, Shu CY, Qin Q, Hirschler L, Warnking JM, Barbier EL, Wei Z, Lu H, Herman P, Hyder F, Liu ZJ, Liang Z, Thompson GJ. High-resolution relaxometry-based calibrated fMRI in murine brain: Metabolic differences between awake and anesthetized states. J Cereb Blood Flow Metab 2022; 42:811-825. [PMID: 34910894 PMCID: PMC9014688 DOI: 10.1177/0271678x211062279] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Functional magnetic resonance imaging (fMRI) techniques using the blood-oxygen level-dependent (BOLD) signal have shown great potential as clinical biomarkers of disease. Thus, using these techniques in preclinical rodent models is an urgent need. Calibrated fMRI is a promising technique that can provide high-resolution mapping of cerebral oxygen metabolism (CMRO2). However, calibrated fMRI is difficult to use in rodent models for several reasons: rodents are anesthetized, stimulation-induced changes are small, and gas challenges induce noisy CMRO2 predictions. We used, in mice, a relaxometry-based calibrated fMRI method which uses cerebral blood flow (CBF) and the BOLD-sensitive magnetic relaxation component, R2', the same parameter derived in the deoxyhemoglobin-dilution model of calibrated fMRI. This method does not use any gas challenges, which we tested on mice in both awake and anesthetized states. As anesthesia induces a whole-brain change, our protocol allowed us to overcome the former limitations of rodent studies using calibrated fMRI. We revealed 1.5-2 times higher CMRO2, dependent upon brain region, in the awake state versus the anesthetized state. Our results agree with alternative measurements of whole-brain CMRO2 in the same mice and previous human anesthesia studies. The use of calibrated fMRI in rodents has much potential for preclinical fMRI.
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Affiliation(s)
- Mengyang Xu
- iHuman Institute, ShanghaiTech University, Shanghai, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Binshi Bo
- CAS Center for Excellence in Brain Sciences and Intelligence Technology, Institute of Neuroscience, Chinese Academy of Sciences, Shanghai, China
| | - Mengchao Pei
- CAS Center for Excellence in Brain Sciences and Intelligence Technology, Institute of Neuroscience, Chinese Academy of Sciences, Shanghai, China
| | - Yuyan Chen
- CAS Center for Excellence in Brain Sciences and Intelligence Technology, Institute of Neuroscience, Chinese Academy of Sciences, Shanghai, China
| | - Christina Y Shu
- Biomedical Engineering, Yale University, New Haven, CT, USA.,Magnetic Resonance Research Center (MRRC), Yale University, New Haven, CT, USA
| | - Qikai Qin
- iHuman Institute, ShanghaiTech University, Shanghai, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
| | - Lydiane Hirschler
- Grenoble Institut des Neurosciences, Inserm, Univ. Grenoble Alpes, Grenoble, France.,C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Jan M Warnking
- Grenoble Institut des Neurosciences, Inserm, Univ. Grenoble Alpes, Grenoble, France
| | - Emmanuel L Barbier
- Grenoble Institut des Neurosciences, Inserm, Univ. Grenoble Alpes, Grenoble, France
| | - Zhiliang Wei
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, USA
| | - Hanzhang Lu
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, USA
| | - Peter Herman
- Magnetic Resonance Research Center (MRRC), Yale University, New Haven, CT, USA.,Quantitative Neuroscience with Magnetic Resonance (QNMR) Core Center, Yale University, New Haven, CT, USA.,Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA
| | - Fahmeed Hyder
- Biomedical Engineering, Yale University, New Haven, CT, USA.,Magnetic Resonance Research Center (MRRC), Yale University, New Haven, CT, USA.,Quantitative Neuroscience with Magnetic Resonance (QNMR) Core Center, Yale University, New Haven, CT, USA.,Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA
| | - Zhi-Jie Liu
- iHuman Institute, ShanghaiTech University, Shanghai, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
| | - Zhifeng Liang
- CAS Center for Excellence in Brain Sciences and Intelligence Technology, Institute of Neuroscience, Chinese Academy of Sciences, Shanghai, China
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5
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Jufar AH, Lankadeva YR, May CN, Cochrane AD, Marino B, Bellomo R, Evans RG. Renal and Cerebral Hypoxia and Inflammation During Cardiopulmonary Bypass. Compr Physiol 2021; 12:2799-2834. [PMID: 34964119 DOI: 10.1002/cphy.c210019] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cardiac surgery-associated acute kidney injury and brain injury remain common despite ongoing efforts to improve both the equipment and procedures deployed during cardiopulmonary bypass (CPB). The pathophysiology of injury of the kidney and brain during CPB is not completely understood. Nevertheless, renal (particularly in the medulla) and cerebral hypoxia and inflammation likely play critical roles. Multiple practical factors, including depth and mode of anesthesia, hemodilution, pump flow, and arterial pressure can influence oxygenation of the brain and kidney during CPB. Critically, these factors may have differential effects on these two vital organs. Systemic inflammatory pathways are activated during CPB through activation of the complement system, coagulation pathways, leukocytes, and the release of inflammatory cytokines. Local inflammation in the brain and kidney may be aggravated by ischemia (and thus hypoxia) and reperfusion (and thus oxidative stress) and activation of resident and infiltrating inflammatory cells. Various strategies, including manipulating perfusion conditions and administration of pharmacotherapies, could potentially be deployed to avoid or attenuate hypoxia and inflammation during CPB. Regarding manipulating perfusion conditions, based on experimental and clinical data, increasing standard pump flow and arterial pressure during CPB appears to offer the best hope to avoid hypoxia and injury, at least in the kidney. Pharmacological approaches, including use of anti-inflammatory agents such as dexmedetomidine and erythropoietin, have shown promise in preclinical models but have not been adequately tested in human trials. However, evidence for beneficial effects of corticosteroids on renal and neurological outcomes is lacking. © 2021 American Physiological Society. Compr Physiol 11:1-36, 2021.
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Affiliation(s)
- Alemayehu H Jufar
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, Australia.,Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Yugeesh R Lankadeva
- Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia.,Department of Critical Care, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Victoria, Australia
| | - Clive N May
- Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia.,Department of Critical Care, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Victoria, Australia
| | - Andrew D Cochrane
- Department of Cardiothoracic Surgery, Monash Health and Department of Surgery (School of Clinical Sciences at Monash Health), Monash University, Melbourne, Victoria, Australia
| | - Bruno Marino
- Cellsaving and Perfusion Resources, Melbourne, Victoria, Australia
| | - Rinaldo Bellomo
- Department of Critical Care, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Victoria, Australia.,Department of Intensive Care, Austin Health, Heidelberg, Victoria, Australia
| | - Roger G Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, Australia.,Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
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6
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Froese L, Dian J, Gomez A, Batson C, Sainbhi AS, Zeiler FA. Association Between Processed Electroencephalogram-Based Objectively Measured Depth of Sedation and Cerebrovascular Response: A Systematic Scoping Overview of the Human and Animal Literature. Front Neurol 2021; 12:692207. [PMID: 34484100 PMCID: PMC8415224 DOI: 10.3389/fneur.2021.692207] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 07/21/2021] [Indexed: 11/24/2022] Open
Abstract
Background: Current understanding of the impact that sedative agents have on neurovascular coupling, cerebral blood flow (CBF) and cerebrovascular response remains uncertain. One confounding factor regarding the impact of sedative agents is the depth of sedation, which is often determined at the bedside using clinical examination scoring systems. Such systems do not objectively account for sedation depth at the neurovascular level. As the depth of sedation can impact CBF and cerebral metabolism, the need for objective assessments of sedation depth is key. This is particularly the case in traumatic brain injury (TBI), where emerging literature suggests that cerebrovascular dysfunction dominates the burden of physiological dysfunction. Processed electroencephalogram (EEG) entropy measures are one possible solution to objectively quantify depth of sedation. Such measures are widely employed within anesthesia and are easy to employ at the bedside. However, the association between such EEG measures and cerebrovascular response remains unclear. Thus, to improve our understanding of the relationship between objectively measured depth of sedation and cerebrovascular response, we performed a scoping review of the literature. Methods: A systematically conduced scoping review of the existing literature on objectively measured sedation depth and CBF/cerebrovascular response was performed, search multiple databases from inception to November 2020. All available literature was reviewed to assess the association between objective sedation depth [as measured through processed electroencephalogram (EEG)] and CBF/cerebral autoregulation. Results: A total of 13 articles, 12 on adult humans and 1 on animal models, were identified. Initiation of sedation was found to decrease processed EEG entropy and CBF/cerebrovascular response measures. However, after this initial drop in values there is a wide range of responses in CBF seen. There were limited statistically reproduceable associations between processed EEG and CBF/cerebrovascular response. The literature body remains heterogeneous in both pathological states studied and sedative agent utilized, limiting the strength of conclusions that can be made. Conclusions: Conclusions about sedation depth, neurovascular coupling, CBF, and cerebrovascular response are limited. Much further work is required to outline the impact of sedation on neurovascular coupling.
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Affiliation(s)
- Logan Froese
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada
| | - Joshua Dian
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Alwyn Gomez
- Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.,Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Carleen Batson
- Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Amanjyot Singh Sainbhi
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada
| | - Frederick A Zeiler
- Biomedical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada.,Section of Neurosurgery, Department of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.,Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada.,Centre on Aging, University of Manitoba, Winnipeg, MB, Canada.,Division of Anaesthesia, Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
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7
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Wang J, Sun P, Liang P. Neuropsychopharmacological effects of midazolam on the human brain. Brain Inform 2020; 7:15. [PMID: 33170396 PMCID: PMC7655878 DOI: 10.1186/s40708-020-00116-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 10/26/2020] [Indexed: 12/17/2022] Open
Abstract
As a commonly used anesthetic agent, midazolam has the properties of water-soluble, rapid onset, and short duration of action. With the rapid development in the field of neuroimaging, numerous studies have investigated how midazolam acts on the human brain to induce the alteration of consciousness. However, the neural bases of midazolam-induced sedation or anesthesia remain beginning to be understood in detail. In this review, we summarize findings from neuroimaging studies that have used midazolam to study altered consciousness at different levels and content. We also compare the results to those of neuroimaging studies using diverse anesthetic agents and describe the common neural correlates of anesthetic-induced alteration of consciousness.
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Affiliation(s)
- Junkai Wang
- School of Psychology, Capital Normal University, Haidian District, Beijing, 100048, China.,Beijing Key Laboratory of Learning and Cognition, Beijing, China.,Department of Psychology, Tsinghua University, Haidian District, Beijing, 100084, China
| | - Pei Sun
- Department of Psychology, Tsinghua University, Haidian District, Beijing, 100084, China.
| | - Peipeng Liang
- School of Psychology, Capital Normal University, Haidian District, Beijing, 100048, China. .,Beijing Key Laboratory of Learning and Cognition, Beijing, China.
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8
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Minhas JS, Rook W, Panerai RB, Hoiland RL, Ainslie PN, Thompson JP, Mistri AK, Robinson TG. Pathophysiological and clinical considerations in the perioperative care of patients with a previous ischaemic stroke: a multidisciplinary narrative review. Br J Anaesth 2020; 124:183-196. [PMID: 31813569 PMCID: PMC7034810 DOI: 10.1016/j.bja.2019.10.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 09/24/2019] [Accepted: 10/18/2019] [Indexed: 12/28/2022] Open
Abstract
With an ageing population and increasing incidence of cerebrovascular disease, an increasing number of patients presenting for routine and emergency surgery have a prior history of stroke. This presents a challenge for pre-, intra-, and postoperative management as the neurological risk is considerably higher. Evidence is lacking around anaesthetic practice for patients with vascular neurological vulnerability. Through understanding the pathophysiological changes that occur after stroke, insight into the susceptibilities of the cerebral vasculature to intrinsic and extrinsic factors can be developed. Increasing understanding of post-stroke systemic and cerebral haemodynamics has provided improved outcomes from stroke and more robust secondary prevention, although this knowledge has yet to be applied to our delivery of anaesthesia in those with prior stroke. This review describes the key pathophysiological and clinical considerations that inform clinicians providing perioperative care for patients with a prior diagnosis of stroke.
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Affiliation(s)
- Jatinder S Minhas
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHIASM) Research Group, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK.
| | - William Rook
- Academic Department of Anaesthesia, Critical Care, Pain, and Resuscitation, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Ronney B Panerai
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHIASM) Research Group, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK; National Institute for Health Research, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
| | - Ryan L Hoiland
- Centre for Heart, Lung, and Vascular Health, University of British Columbia, Kelowna, BC, Canada
| | - Phil N Ainslie
- Centre for Heart, Lung, and Vascular Health, University of British Columbia, Kelowna, BC, Canada
| | - Jonathan P Thompson
- Anaesthesia and Critical Care, Department of Cardiovascular Sciences, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK; University Hospitals of Leicester NHS Trust, Leicester Royal Infirmary, Leicester, UK
| | - Amit K Mistri
- University Hospitals of Leicester NHS Trust, Leicester Royal Infirmary, Leicester, UK
| | - Thompson G Robinson
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHIASM) Research Group, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK; National Institute for Health Research, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
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9
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Landau AM, Noer O, Alstrup AKO, Audrain H, Wegener G, Gjedde A, Doudet DJ, Winterdahl M. Type of Anaesthetic Influences [ 11C]MDL100,907 Binding to 5HT 2A Receptors in Porcine Brain. Mol Imaging Biol 2020; 22:797-804. [PMID: 31993926 DOI: 10.1007/s11307-020-01476-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE Anaesthesia routinely is used in animal neuroimaging in order to reduce head motion artefacts and minimize the influence of stress. However, anaesthetics can modify radioligand binding profiles at receptor targets studied by positron emission tomography (PET). Here, we determined the effects of two routine anaesthetics on the binding of a tracer of the serotonin 5HT2A receptors. PROCEDURES Isoflurane- and propofol-anesthetised Göttingen minipigs were imaged with [11C]MDL100,907 PET and analysed using regions of interest and statistical non-parametric mapping. RESULTS The binding potentials of the tracer in striatum under isoflurane anaesthesia significantly exceeded those obtained under propofol anaesthesia, an effect we attribute to the higher blood flow in brain induced by the former. CONCLUSIONS Interactions between radioligands and anaesthesia must be carefully evaluated in the design of in vivo neuroimaging and interpretation of data.
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Affiliation(s)
- Anne M Landau
- Department of Nuclear Medicine and PET, Aarhus University, Aarhus, Denmark. .,Translational Neuropsychiatry Unit, Aarhus University, Aarhus, Denmark.
| | - Ove Noer
- Department of Nuclear Medicine and PET, Aarhus University, Aarhus, Denmark
| | | | - Hélène Audrain
- Department of Nuclear Medicine and PET, Aarhus University, Aarhus, Denmark
| | - Gregers Wegener
- Translational Neuropsychiatry Unit, Aarhus University, Aarhus, Denmark
| | - Albert Gjedde
- Department of Nuclear Medicine and PET, Aarhus University, Aarhus, Denmark.,Department of Nuclear Medicine, University of Southern Denmark, Odense University Hospital, Odense, Denmark.,Department of Neurology and Neurosurgery, McGill University, Montreal, Canada
| | - Doris J Doudet
- Department of Medicine/Neurology, University of British Columbia, Vancouver, Canada
| | - Michael Winterdahl
- Department of Nuclear Medicine and PET, Aarhus University, Aarhus, Denmark
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10
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Arakawa R, Farde L, Matsumoto J, Kanegawa N, Yakushev I, Yang KC, Takano A. Potential Effect of Prolonged Sevoflurane Anesthesia on the Kinetics of [ 11C]Raclopride in Non-human Primates. Mol Imaging Biol 2019; 20:183-187. [PMID: 28916921 PMCID: PMC5862918 DOI: 10.1007/s11307-017-1120-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Purpose Positron emission tomography (PET) in non-human primates (NHP) is commonly performed under anesthesia, with sevoflurane being a widely used inhaled anesthetic. PET measurement in NHP can be repeated, and a difference in radioligand kinetics has previously been observed between the first and second PET measurement on the same day using sevoflurane anesthesia. In this study, we evaluated the effect of prolonged sevoflurane anesthesia on kinetics and binding potential (BPND) of [11C]raclopride in NHP. Procedures Three cynomolgus monkeys underwent two to three PET measurements with [11C]raclopride under continuous sevoflurane anesthesia on the same day. The concentration of sevoflurane was adjusted according to the general conditions and safety parameters of the NHP. Time to peak (TTP) radioactivity in the striatum was estimated from time-activity curves (TACs). The BPND in the striatum was calculated by the simplified reference tissue model using the cerebellum as reference region. Results In each NHP, the TTP became shorter in the later PET measurements than in the first one. Across all measurements (n = 8), concentration of sevoflurane correlated with TTP (Spearman’s ρ = − 0.79, p = 0.03), but not with BPND (ρ = − 0.25, p = 0.55). Conclusions These data suggest that sevoflurane affects the shape of TACs but has no evident effect on BPND in consecutive PET measurements.
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Affiliation(s)
- Ryosuke Arakawa
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden.
| | - Lars Farde
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden.,Personalized Health Care and Biomarkers, AstraZeneca PET Science Center, Karolinska Institutet, Stockholm, Sweden
| | - Junya Matsumoto
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden.,Department of Neuropsychiatry, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Naoki Kanegawa
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Igor Yakushev
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden.,Department of Nuclear Medicine and TUM Neuroimaging Center (TUM-NIC), Technische Universität München, Munich, Germany
| | - Kai-Chun Yang
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Akihiro Takano
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
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11
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Slupe AM, Kirsch JR. Effects of anesthesia on cerebral blood flow, metabolism, and neuroprotection. J Cereb Blood Flow Metab 2018; 38:2192-2208. [PMID: 30009645 PMCID: PMC6282215 DOI: 10.1177/0271678x18789273] [Citation(s) in RCA: 160] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Revised: 06/11/2018] [Accepted: 06/25/2018] [Indexed: 12/12/2022]
Abstract
Administration of anesthetic agents fundamentally shifts the responsibility for maintenance of homeostasis from the patient and their intrinsic physiological regulatory mechanisms to the anesthesiologist. Continuous delivery of oxygen and nutrients to the brain is necessary to prevent irreversible injury and arises from a complex series of regulatory mechanisms that ensure uninterrupted cerebral blood flow. Our understanding of these regulatory mechanisms and the effects of anesthetics on them has been driven by the tireless work of pioneers in the field. It is of paramount importance that the anesthesiologist shares this understanding. Herein, we will review the physiological determinants of cerebral blood flow and how delivery of anesthesia impacts these processes.
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Affiliation(s)
- Andrew M Slupe
- Department of Anesthesiology and Perioperative Medicine, Oregon Health and Science University, Portland, OR, USA
| | - Jeffrey R Kirsch
- Department of Anesthesiology and Perioperative Medicine, Oregon Health and Science University, Portland, OR, USA
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Impact of Global Mean Normalization on Regional Glucose Metabolism in the Human Brain. Neural Plast 2018; 2018:6120925. [PMID: 30008742 PMCID: PMC6020504 DOI: 10.1155/2018/6120925] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 02/20/2018] [Accepted: 04/03/2018] [Indexed: 02/02/2023] Open
Abstract
Because the human brain consumes a disproportionate fraction of the resting body's energy, positron emission tomography (PET) measurements of absolute glucose metabolism (CMRglc) can serve as disease biomarkers. Global mean normalization (GMN) of PET data reveals disease-based differences from healthy individuals as fractional changes across regions relative to a global mean. To assess the impact of GMN applied to metabolic data, we compared CMRglc with and without GMN in healthy awake volunteers with eyes closed (i.e., control) against specific physiological/clinical states, including healthy/awake with eyes open, healthy/awake but congenitally blind, healthy/sedated with anesthetics, and patients with disorders of consciousness. Without GMN, global CMRglc alterations compared to control were detected in all conditions except in congenitally blind where regional CMRglc variations were detected in the visual cortex. However, GMN introduced regional and bidirectional CMRglc changes at smaller fractions of the quantitative delocalized changes. While global information was lost with GMN, the quantitative approach (i.e., a validated method for quantitative baseline metabolic activity without GMN) not only preserved global CMRglc alterations induced by opening eyes, sedation, and varying consciousness but also detected regional CMRglc variations in the congenitally blind. These results caution the use of GMN upon PET-measured CMRglc data in health and disease.
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Laaksonen L, Kallioinen M, Långsjö J, Laitio T, Scheinin A, Scheinin J, Kaisti K, Maksimow A, Kallionpää RE, Rajala V, Johansson J, Kantonen O, Nyman M, Sirén S, Valli K, Revonsuo A, Solin O, Vahlberg T, Alkire M, Scheinin H. Comparative effects of dexmedetomidine, propofol, sevoflurane, and S-ketamine on regional cerebral glucose metabolism in humans: a positron emission tomography study. Br J Anaesth 2018; 121:281-290. [PMID: 29935583 DOI: 10.1016/j.bja.2018.04.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2017] [Indexed: 11/28/2022] Open
Abstract
INTRODUCTION The highly selective α2-agonist dexmedetomidine has become a popular sedative for neurointensive care patients. However, earlier studies have raised concern that dexmedetomidine might reduce cerebral blood flow without a concomitant decrease in metabolism. Here, we compared the effects of dexmedetomidine on the regional cerebral metabolic rate of glucose (CMRglu) with three commonly used anaesthetic drugs at equi-sedative doses. METHODS One hundred and sixty healthy male subjects were randomised to EC50 for verbal command of dexmedetomidine (1.5 ng ml-1; n=40), propofol (1.7 μg ml-1; n=40), sevoflurane (0.9% end-tidal; n=40) or S-ketamine (0.75 μg ml-1; n=20) or placebo (n=20). Anaesthetics were administered using target-controlled infusion or vapouriser with end-tidal monitoring. 18F-labelled fluorodeoxyglucose was administered 20 min after commencement of anaesthetic administration, and high-resolution positron emission tomography with arterial blood activity samples was used to quantify absolute CMRglu for whole brain and 15 brain regions. RESULTS At the time of [F18]fluorodeoxyglucose injection, 55% of dexmedetomidine, 45% of propofol, 85% of sevoflurane, 45% of S-ketamine, and 0% of placebo subjects were unresponsive. Whole brain CMRglu was 63%, 71%, 71%, and 96% of placebo in the dexmedetomidine, propofol, sevoflurane, and S-ketamine groups, respectively (P<0.001 between the groups). The lowest CMRglu was observed in nearly all brain regions with dexmedetomidine (P<0.05 compared with all other groups). With S-ketamine, CMRglu did not differ from placebo. CONCLUSIONS At equi-sedative doses in humans, potency in reducing CMRglu was dexmedetomidine>propofol>ketamine=placebo. These findings alleviate concerns for dexmedetomidine-induced vasoconstriction and cerebral ischaemia. CLINICAL TRIAL REGISTRATION NCT02624401.
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Affiliation(s)
- L Laaksonen
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland; Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland.
| | - M Kallioinen
- Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland
| | - J Långsjö
- Department of Intensive Care, Tampere University Hospital, Tampere, Finland
| | - T Laitio
- Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland
| | - A Scheinin
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland; Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland
| | - J Scheinin
- Department of Anaesthesiology, Kuopio University Hospital, Kuopio, Finland
| | - K Kaisti
- Department of Anaesthesiology and Intensive Care, Oulu University Hospital, Oulu, Finland
| | - A Maksimow
- Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland
| | - R E Kallionpää
- Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland; Department of Psychology and Speech-Language Pathology, Turku Brain and Mind Center, University of Turku, Turku, Finland
| | - V Rajala
- Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland
| | - J Johansson
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland; Department of Radiation Sciences, Umeå University, Umeå, Sweden
| | - O Kantonen
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland; Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland; University of California, Irvine, CA, USA
| | - M Nyman
- Department of Radiology, Turku University Hospital, Turku, Finland
| | - S Sirén
- Institute of Biomedicine, University of Turku, Unit of Clinical Pharmacology, Turku University Hospital, Turku, Finland
| | - K Valli
- Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland; Department of Psychology and Speech-Language Pathology, Turku Brain and Mind Center, University of Turku, Turku, Finland; Department of Cognitive Neuroscience and Philosophy, School of Bioscience, University of Skövde, Sweden
| | - A Revonsuo
- Department of Psychology and Speech-Language Pathology, Turku Brain and Mind Center, University of Turku, Turku, Finland; Department of Cognitive Neuroscience and Philosophy, School of Bioscience, University of Skövde, Sweden
| | - O Solin
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
| | - T Vahlberg
- Department of Clinical Medicine, Biostatistics, University of Turku and Turku University Hospital, Turku, Finland
| | - M Alkire
- University of California, Irvine, CA, USA
| | - H Scheinin
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland; Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland; Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
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Liang P, Xu Y, Lan F, Ma D, Li K. Decreased Cerebral Blood Flow in Mesial Thalamus and Precuneus/PCC during Midazolam Induced Sedation Assessed with ASL. Neuroinformatics 2018; 16:403-410. [PMID: 29572600 DOI: 10.1007/s12021-018-9368-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
While some previous work suggests that midazolam-induced light sedation results from the functional disconnection within resting state network, little is known about the underlying alterations of cerebral blood flow (CBF) associated with its effects. A randomized, double-blind, within-subject, cross-over design was adopted, while 12 healthy young volunteers were scanned with arterial spin-labeling (ASL) perfusion MRI both before and after an injection of either saline or midazolam. The contrast of MRI signal before and after midazolam administration revealed the CBF decrease in the bilateral mesial thalamus and precuneus/posterior cingulate cortex (PCC). These effects were confirmed after controlling for any effect of injection as well as head motions. These findings provide new evidences that midazolam-induced light sedation is related to the disruption of cortical functional integration, and have new implications to the neural basis of consciousness.
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Affiliation(s)
- Peipeng Liang
- Department of Radiology, Xuanwu Hospital, Capital Medical University, 45 Chang Chun Street, Xuan Wu District, Beijing, 100053, China. .,Beijing Key Laboratory of Magnetic Resonance Imaging and Brain Informatics, Beijing, 100053, China.
| | - Yachao Xu
- Department of Anesthesiology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China
| | - Fei Lan
- Department of Anesthesiology, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China
| | - Daqing Ma
- Anaesthetcis, Pain Medicine and Intensive Care, Department of Surgery & Cancer, Imperial College London, Chelsea & Westminster Hospital, 369 Fulham Road, London, SW10 9NH, UK
| | - Kuncheng Li
- Department of Radiology, Xuanwu Hospital, Capital Medical University, 45 Chang Chun Street, Xuan Wu District, Beijing, 100053, China.,Beijing Key Laboratory of Magnetic Resonance Imaging and Brain Informatics, Beijing, 100053, China
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Scheinin H, Alkire EC, Scheinin A, Alkire MT, Kantonen O, Långsjö J. Using Positron Emission Tomography in Revealing the Mystery of General Anesthesia: Study Design Challenges and Opportunities. Methods Enzymol 2018; 603:279-303. [PMID: 29673531 DOI: 10.1016/bs.mie.2018.01.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Functional neuroimaging with positron emission tomography (PET) is one of the cornerstones for studying the central nervous system effects of general anesthetics and anesthesia mechanisms. General anesthesia offers a unique and safe way to directly manipulate consciousness, and can thus be used as a powerful research tool to study the neurobiology of human consciousness. In this chapter, we will address the possibilities of PET imaging in revealing the mysteries of general anesthesia and anesthetic induced unconsciousness and summarize some of the recent advancements in the field. Importantly, we will discuss possible ways to separate brain activity changes associated with the changing level of consciousness from the concentration or dose-dependent direct or indirect drug effects on the brain. We will try to demonstrate how state-of-the-art clinical pharmacology, use of specific anesthetic drugs, and innovative study design solutions could be utilized.
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Affiliation(s)
- Harry Scheinin
- Turku PET Centre, University of Turku and the Hospital District of Southwest Finland, Turku, Finland; Turku University Hospital, Turku, Finland; Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland.
| | - Emilee C Alkire
- The Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA, United States
| | - Annalotta Scheinin
- Turku PET Centre, University of Turku and the Hospital District of Southwest Finland, Turku, Finland; Turku University Hospital, Turku, Finland
| | - Michael T Alkire
- The Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA, United States; VA Long Beach Healthcare System, Long Beach, CA, United States
| | - Oskari Kantonen
- Turku University Hospital, Turku, Finland; The Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA, United States
| | - Jaakko Långsjö
- Turku PET Centre, University of Turku and the Hospital District of Southwest Finland, Turku, Finland; Tampere University Hospital, Tampere, Finland
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Effects of hyperventilation on cerebral oxygen saturation estimated using near-infrared spectroscopy: A randomised comparison between propofol and sevoflurane anaesthesia. Eur J Anaesthesiol 2018; 33:929-935. [PMID: 27802250 DOI: 10.1097/eja.0000000000000507] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Near-infrared spectroscopy estimates cerebral regional tissue oxygen saturation (rSO2), which may decrease under hyperventilation. Propofol and sevoflurane act differently on cerebral blood vessels. Consequently, cerebral blood flow during hyperventilation with propofol and sevoflurane anaesthesia may differ. OBJECTIVES The first aim of this study was to compare the changes in rSO2 between propofol and sevoflurane anaesthesia during hyperventilation. The second aim was to assess changes in rSO2 with ventilation changes. DESIGN A randomised, open-label study. SETTING University of Yamanashi Hospital, Yamanashi, Japan from January 2014 to September 2014. PARTICIPANTS Fifty American Society of Anesthesiologists physical status 1 or 2 adult patients who were scheduled for elective abdominal surgery were assigned randomly to receive either propofol or sevoflurane anaesthesia. Exclusion criterion was a known history of cerebral disease such as cerebral infarction, cerebral haemorrhage, transient ischaemic attack and subarachnoid haemorrhage. INTERVENTIONS After induction of anaesthesia but before the start of surgery, rSO2, arterial carbon dioxide partial pressure (PaCO2) and arterial oxygen saturation were measured. Measurements were repeated at 5-min intervals during 15 min of hyperventilation with a PaCO2 around 30 mmHg (4 kPa), and again after ventilation was normalised. MAIN OUTCOME MEASURES The primary outcome was the difference of changes in rSO2 between propofol anaesthesia and sevoflurane anaesthesia during and after hyperventilation. The second outcome was change in rSO2 after the initiation of hyperventilation and after the normalisation of ventilation. RESULTS Changes of rSO2 during hyperventilation were -10 ± 7% (left) and -11 ± 8% (right) in the propofol group, and -10 ± 8% (left) and -9 ± 7% (right) in the sevoflurane group. After normalisation of PaCO2, rSO2 returned to baseline values. Arterial oxygen saturation remained stable throughout the measurement period. The rSO2 values were similar in the propofol and the sevoflurane groups at each time point. CONCLUSION The effects of hyperventilation on estimated rSO2 were similar with propofol and sevoflurane anaesthesia. Changes in rSO2 correlated well with ventilation changes. TRIAL REGISTRATION Japan Primary Registries Network (JPRN); UMIN-CTR ID; UMIN000010640.
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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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Gharagouzloo CA, Timms L, Qiao J, Fang Z, Nneji J, Pandya A, Kulkarni P, van de Ven AL, Ferris C, Sridhar S. Quantitative vascular neuroimaging of the rat brain using superparamagnetic nanoparticles: New insights on vascular organization and brain function. Neuroimage 2017; 163:24-33. [PMID: 28889004 PMCID: PMC5824692 DOI: 10.1016/j.neuroimage.2017.09.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 08/30/2017] [Accepted: 09/01/2017] [Indexed: 02/08/2023] Open
Abstract
A method called Quantitative Ultra-Short Time-to-Echo Contrast Enhanced (QUTE-CE) Magnetic Resonance Imaging (MRI) which utilizes superparamagnetic iron oxide nanoparticles (SPIONs) as a contrast agent to yield positive contrast angiograms with high clarity and definition is applied to the whole live rat brain. QUTE-CE MRI intensity data are particularly well suited for measuring quantitative cerebral blood volume (qCBV). A global map of qCBV in the awake resting-state with unprecedented detail was created via application of a 3D MRI rat brain atlas with 173 segmented and annotated brain areas. From this map we identified two distributed, integrated neural circuits showing the highest capillary densities in the brain. One is the neural circuitry involved with the primary senses of smell, hearing and vision and the other is the neural circuitry of memory. Under isoflurane anesthesia, these same circuits showed significant decreases in qCBV suggesting a role in consciousness. Neural circuits in the brainstem associated with the reticular activating system and the maintenance of respiration, body temperature and cardiovascular function showed an increase in qCBV with anesthesia. During awake CO2 challenge, 84 regions showed significant increases relative to an awake baseline state. This CO2 response provides a measure of cerebral vascular reactivity and regional perfusion reserve with the highest response measured in the somatosensory cortex. These results demonstrate the utility of QUTE-CE MRI for qCBV analysis and offer a new perspective on brain function and vascular organization.
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Affiliation(s)
- Codi A. Gharagouzloo
- Nanomedicine Science and Technology Center, Northeastern University, Boston MA
- Department of Bioengineering, Northeastern University, Boston MA
- Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Liam Timms
- Nanomedicine Science and Technology Center, Northeastern University, Boston MA
- Department of Physics, Northeastern University, Boston MA
| | - Ju Qiao
- Nanomedicine Science and Technology Center, Northeastern University, Boston MA
- Department of Mechanical and Industrial Engineering, Northeastern University, Boston MA
| | - Zihang Fang
- Nanomedicine Science and Technology Center, Northeastern University, Boston MA
| | - Joseph Nneji
- Nanomedicine Science and Technology Center, Northeastern University, Boston MA
| | - Aniket Pandya
- Nanomedicine Science and Technology Center, Northeastern University, Boston MA
| | - Praveen Kulkarni
- Center for Translational NeuroImaging, Northeastern University, Boston MA
- Psychology Department, Northeastern University, Boston MA
| | - Anne L. van de Ven
- Nanomedicine Science and Technology Center, Northeastern University, Boston MA
- Department of Physics, Northeastern University, Boston MA
| | - Craig Ferris
- Center for Translational NeuroImaging, Northeastern University, Boston MA
- Psychology Department, Northeastern University, Boston MA
- Department of Pharmaceutical Sciences, Northeastern University, Boston MA
| | - Srinivas Sridhar
- Nanomedicine Science and Technology Center, Northeastern University, Boston MA
- Department of Bioengineering, Northeastern University, Boston MA
- Department of Physics, Northeastern University, Boston MA
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Anesthesia, brain changes, and behavior: Insights from neural systems biology. Prog Neurobiol 2017; 153:121-160. [PMID: 28189740 DOI: 10.1016/j.pneurobio.2017.01.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 01/19/2017] [Accepted: 01/22/2017] [Indexed: 02/08/2023]
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Positron Emission Tomography: Basic Principles, New Applications, and Studies Under Anesthesia. Int Anesthesiol Clin 2016; 54:109-28. [PMID: 26655512 DOI: 10.1097/aia.0000000000000090] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Arulvelan A, Manikandan S, Easwer HV, Krishnakumar K. Cerebral vascular effects of loading dose of dexmedetomidine: A Transcranial Color Doppler study. Indian J Crit Care Med 2016; 20:9-13. [PMID: 26955211 PMCID: PMC4760000 DOI: 10.4103/0972-5229.173680] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Background: Dexmedetomidine has been widely used in critical care settings because of its property of maintaining stable hemodynamics and inducing conscious sedation. The use of dexmedetomidine is in increasing trend particularly in patients with neurological disorders. Very few studies have focused on the cerebral hemodynamic effects of dexmedetomidine. This study is aimed to address this issue. Methods: Thirty patients without any intracranial pathology were included in this study. Middle cerebral artery flow velocity obtained from transcranial color Doppler was used to assess the cerebral hemodynamic indices. Mean flow velocity (mFV), pulsatility index (PI), cerebral vascular resistant index (CVRi), estimated cerebral perfusion pressure (eCPP), and zero flow pressure (ZFP) were calculated bilaterally at baseline and after infusion of injection Dexmedetomidine 1 mcg/Kg over 10 min. Results: Twenty-six patients completed the study protocol. After administration of loading dose of dexmedetomidine, mFV and eCPP values were significantly decreased in both hemispheres (P < 0.05); PI, CVRi, and ZFP values showed significant increase (P < 0.05) after dexmedetomidine infusion. Conclusion: Increase in PI, CVRi, and ZFP suggests that there is a possibility of an increase in distal cerebral vascular resistance (CVR) with loading dose of dexmedetomidine. Decrease in mFV and eCPP along with an increase in CVR may lead to a decrease in cerebral perfusion. This effect can be exaggerated in patients with preexisting neurological illness. Further studies are needed to evaluate the effect of dexmedetomidine on various other pathological conditions involving brain like traumatic brain injury and vascular malformations.
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Affiliation(s)
- Appavoo Arulvelan
- Department of Anesthesiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Ulloor, Trivandrum, Kerala, India
| | - Sethuraman Manikandan
- Department of Anesthesiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Ulloor, Trivandrum, Kerala, India
| | - Hari Venkat Easwer
- Department of Anesthesiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Ulloor, Trivandrum, Kerala, India
| | - Kesavapisharady Krishnakumar
- Department of Anesthesiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Ulloor, Trivandrum, Kerala, India
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Youngerman BE, Chan AK, Mikell CB, McKhann GM, Sheth SA. A decade of emerging indications: deep brain stimulation in the United States. J Neurosurg 2016; 125:461-71. [PMID: 26722851 DOI: 10.3171/2015.7.jns142599] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Deep brain stimulation (DBS) is an emerging treatment option for an expanding set of neurological and psychiatric diseases. Despite growing enthusiasm, the patterns and implications of this rapid adoption are largely unknown. National trends in DBS surgery performed for all indications between 2002 and 2011 are reported. METHODS Using a national database of hospital discharges, admissions for DBS for 14 indications were identified and categorized as either FDA approved, humanitarian device exempt (HDE), or emerging. Trends over time were examined, differences were analyzed by univariate analyses, and outcomes were analyzed by hierarchical regression analyses. RESULTS Between 2002 and 2011, there were an estimated 30,490 discharges following DBS for approved indications, 1647 for HDE indications, and 2014 for emerging indications. The volume for HDE and emerging indications grew at 36.1% annually in comparison with 7.0% for approved indications. DBS for emerging indications occurred at hospitals with more neurosurgeons and neurologists locally, but not necessarily at those with the highest DBS caseloads. Patients treated for HDE and emerging indications were younger with lower comorbidity scores. HDE and emerging indications were associated with greater rates of reported complications, longer lengths of stay, and greater total costs. CONCLUSIONS DBS for HDE and emerging indications underwent rapid growth in the last decade, and it is not exclusively the most experienced DBS practitioners leading the charge to treat the newest indications. Surgeons may be selecting younger and healthier patients for their early experiences. Differences in reported complication rates warrant further attention and additional costs should be anticipated as surgeons gain experience with new patient populations and targets.
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Affiliation(s)
- Brett E Youngerman
- Department of Neurological Surgery, Columbia University Medical Center, New York, New York; and
| | - Andrew K Chan
- Department of Neurological Surgery, University of California, San Francisco, California
| | - Charles B Mikell
- Department of Neurological Surgery, Columbia University Medical Center, New York, New York; and
| | - Guy M McKhann
- Department of Neurological Surgery, Columbia University Medical Center, New York, New York; and
| | - Sameer A Sheth
- Department of Neurological Surgery, Columbia University Medical Center, New York, New York; and
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Postoperative Structural Brain Changes and Cognitive Dysfunction in Patients with Breast Cancer. PLoS One 2015; 10:e0140655. [PMID: 26536672 PMCID: PMC4633203 DOI: 10.1371/journal.pone.0140655] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 09/29/2015] [Indexed: 12/25/2022] Open
Abstract
Objective The primary purpose of this study was to clarify the influence of the early response to surgery on brain structure and cognitive function in patients with breast cancer. It was hypothesized that the structure of the thalamus would change during the early response after surgery due to the effects of anesthesia and would represent one aspect of an intermediate phenotype of postoperative cognitive dysfunction (POCD). Methods We examined 32 postmenopausal females with breast cancer and 20 age-matched controls. We assessed their cognitive function (attention, memory, and executive function), and performed brain structural MRI 1.5 ± 0.5 days before and 5.6 ± 1.2 days after surgery. Results We found a significant interaction between regional grey matter volume (rGMV) in the thalamus (P < 0.05, familywise error (FWE), small volume correction (SVC)) and one attention domain subtest (P = 0.001, Bonferroni correction) after surgery in the patient group compared with the control group. Furthermore, the changes in attention were significantly associated with sevoflurane anesthetic dose (r2 = 0.247, β = ‒0.471, P = 0.032) and marginally associated with rGMV changes in the thalamus (P = 0.07, FWE, SVC) in the Pt group. Conclusion Our findings suggest that alterations in brain structure, particularly in the thalamus, may occur shortly after surgery and may be associated with attentional dysfunction. This early postoperative response to anesthesia may represent an intermediate phenotype of POCD. It was assumed that patients experiencing other risk factors of POCD, such as the severity of surgery, the occurrence of complications, and pre-existing cognitive impairments, would develop clinical POCD with broad and multiple types of cognitive dysfunction.
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Khodayari-Rostamabad A, Graversen C, Malver LP, Kurita GP, Christrup LL, Sjøgren P, Drewes AM. A cortical source localization analysis of resting EEG data after remifentanil infusion. Clin Neurophysiol 2015; 126:898-905. [DOI: 10.1016/j.clinph.2014.08.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 06/19/2014] [Accepted: 08/14/2014] [Indexed: 11/29/2022]
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Jung HS, Sung TY, Kang H, Kim JS, Kim TY. Cerebral blood flow change during volatile induction in large-dose sevoflurane versus intravenous propofol induction: transcranial Doppler study. Korean J Anesthesiol 2014; 67:323-8. [PMID: 25473461 PMCID: PMC4252344 DOI: 10.4097/kjae.2014.67.5.323] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 07/10/2014] [Accepted: 07/11/2014] [Indexed: 11/11/2022] Open
Abstract
Background The impact of volatile induction using large-dose sevoflurane (VI-S) on cerebral blood flow has not been well investigated. The present study compared the changes in cerebral blood flow of middle cerebral artery using transcranial Doppler (TCD) during VI-S and conventional induction using propofol. Methods Patients undergoing elective lumbar discectomy were randomly allocated to receive either sevoflurane (8%, Group VI-S, n = 11) or target-controlled infusion of propofol (effect site concentration, 3.0 µg/ml; Group P, n = 11) for induction of anesthesia. The following data were recorded before and at 1, 2, and 3 min after commencement of anesthetic induction (T0, T1, T2, and T3, respectively): mean velocity of the middle cerebral artery (VMCA) by TCD, mean blood pressure (MBP), heart rate, bispectral index score (BIS) and end-tidal CO2 (ETCO2). Changes in VMCA and MBP from their values at T0 (ΔVMCA and ΔMBP) at T1, T2, and T3 were also determined. Results BISs at T1, T2 and T3 were significantly less than that at T0 in both groups (P < 0.05). ΔVMCA in Group VI-S at T2 and T3 (18.1% and 12.4%, respectively) were significantly greater than those in Group P (-7.6% and -19.8%, P = 0.006 and P < 0.001, respectively), whereas ETCO2 and ΔMBP showed no significant intergroup difference. Conclusions VI-S using large-dose sevoflurane increases cerebral blood flow resulting in luxury cerebral flow-metabolism mismatch, while conventional propofol induction maintains cerebral flow-metabolism coupling. This mismatch in VI-S may have to be considered in clinical application of VI-S.
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Affiliation(s)
- Hwa Sung Jung
- Department of Anesthesiology and Pain Medicine, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung, Korea
| | - Tae-Yun Sung
- Department of Anesthesiology and Pain Medicine, Konyang University Hospital, Konyang University College of Medicine, Daejeon, Korea
| | - Hyun Kang
- Department of Anesthesiology and Pain Medicine, Chung-Ang University Medical Center, Chung-Ang University School of Medicine, Seoul, Korea
| | - Jin Sun Kim
- Department of Anesthesiology and Pain Medicine, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung, Korea
| | - Tae-Yop Kim
- Department of Anesthesiology and Pain Medicine, Konkuk University Medical Center, Research Institute of Medical Science, Konkuk University School of Medicine, Seoul, Korea
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Graversen C, Malver LP, Kurita GP, Staahl C, Christrup LL, Sjøgren P, Drewes AM. Altered Frequency Distribution in the Electroencephalogram is Correlated to the Analgesic Effect of Remifentanil. Basic Clin Pharmacol Toxicol 2014; 116:414-22. [DOI: 10.1111/bcpt.12330] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 09/15/2014] [Indexed: 11/29/2022]
Affiliation(s)
- Carina Graversen
- Mech-Sense; Department of Gastroenterology and Hepatology; Aalborg University Hospital; Aalborg Denmark
| | - Lasse P. Malver
- Mech-Sense; Department of Gastroenterology and Hepatology; Aalborg University Hospital; Aalborg Denmark
| | - Geana P. Kurita
- The Multidisciplinary Pain Centre; Rigshospitalet; University of Copenhagen; Copenhagen Denmark
- Section of Palliative Medicine; Department of Oncology; Rigshospitalet; Copenhagen University Hospital; Copenhagen Denmark
| | - Camilla Staahl
- Mech-Sense; Department of Gastroenterology and Hepatology; Aalborg University Hospital; Aalborg Denmark
| | - Lona L. Christrup
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Per Sjøgren
- Section of Palliative Medicine; Department of Oncology; Rigshospitalet; Copenhagen University Hospital; Copenhagen Denmark
| | - Asbjørn M. Drewes
- Mech-Sense; Department of Gastroenterology and Hepatology; Aalborg University Hospital; Aalborg Denmark
- Center for Sensory-Motor Interactions (SMI); Department of Health Science and Technology; Aalborg University; Aalborg Denmark
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Kaskinoro K, Maksimow A, Georgiadis S, Långsjö J, Scheinin H, Karjalainen P, Jääskeläinen SK. Electroencephalogram reactivity to verbal command after dexmedetomidine, propofol and sevoflurane-induced unresponsiveness. Anaesthesia 2014; 70:190-204. [DOI: 10.1111/anae.12868] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2014] [Indexed: 12/29/2022]
Affiliation(s)
- K. Kaskinoro
- Department of Perioperative Services; Intensive Care and Pain Medicine; Turku University Hospital; Turku Finland
| | - A. Maksimow
- Department of Perioperative Services; Intensive Care and Pain Medicine; Turku University Hospital; Turku Finland
| | - S. Georgiadis
- Department of Applied Physics; University of Eastern Finland; Kuopio Finland
| | - J. Långsjö
- Turku PET Centre; University of Turku; Turku Finland
- Intensive Care Unit; Tampere University Hospital; Tampere Finland
| | - H. Scheinin
- Turku PET Centre and Department of Pharmacology and Clinical Pharmacology; University of Turku; Turku Finland
| | - P. Karjalainen
- Department of Applied Physics; University of Eastern Finland; Kuopio Finland
| | - S. K. Jääskeläinen
- Departments of Clinical Neurophysiology; Turku University Hospital and Clinical Neurophysiology; University of Turku; Turku Finland
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Walter B, Eiselt M, Cumming P, Xiong G, Hinz R, Uthe S, Brust P, Bauer R. Resistance of brain glucose metabolism to thiopental-induced CNS depression in newborn piglets. Int J Dev Neurosci 2013; 31:157-64. [PMID: 23305916 DOI: 10.1016/j.ijdevneu.2012.12.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2012] [Accepted: 12/30/2012] [Indexed: 10/27/2022] Open
Abstract
The transition from mild sedation to deep anaesthesia is marked by the phenomenon of burst suppression (BS). FDG-PET studies show that the cerebral metabolic rate for glucose (CMRglc) declines dramatically with onset of BS in the adult brain. Global CMRglc increases substantially in the post-natal period and achieves its maximum in preadolescence. However, the impact of post-natal brain development on the vulnerability of CMRglc to the onset of BS has not been documented. Therefore, cerebral blood flow and metabolism were measured using a variant of the Kety-Schmidt method, in conjunction with quantitative regional estimation of brain glucose uptake by FDG-PET in groups of neonate and juvenile pigs, under a condition of light sedation or after induction of deep anaesthesia with thiopental. Quantification of simultaneous ECoG recordings was used to establish the correlation between anaesthesia-related changes in brain electrical activity and the observed cerebrometabolic changes. In the condition of light sedation the magnitude of CMRglc was approximately 20% higher in the older pigs, with the greatest developmental increase evident in the cerebral cortex and basal ganglia (P<0.05). Onset of BS was associated with 20-40% declines in CMRglc. Subtraction of the mean parametric maps for CMRglc showed the absolute reductions in CMRglc evoked by thiopental anaesthesia to be two-fold greater in the pre-adolescent pigs than in the neonates (P<0.05). Thus, the lesser suppression of brain energy demand of neonate brain during deep anaesthesia represents a reduced part of thiopental suppressing brain metabolism in neonates.
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Affiliation(s)
- Bernd Walter
- Institute of Molecular Cell Biology, Jena University Hospital, Friedrich Schiller University, Jena, Germany
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SCHLÜNZEN L, JUUL N, HANSEN KV, COLD GE. Regional cerebral blood flow and glucose metabolism during propofol anaesthesia in healthy subjects studied with positron emission tomography. Acta Anaesthesiol Scand 2012; 56:248-55. [PMID: 22091956 DOI: 10.1111/j.1399-6576.2011.02561.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/27/2011] [Indexed: 12/14/2022]
Abstract
BACKGROUND General anaesthetics can alter the relationship between regional cerebral glucose metabolism rate (rGMR) and regional cerebral blood flow (rCBF). With the present study, we wanted to assess quantitatively the effects of propofol on rCBF and rGMR in the same healthy volunteers measured with positron emission tomography (PET). METHODS (15)O-labelled water and (18)F fluorodeoxyglucose were used as PET tracers to determine rCBF and rGMR, respectively, in eight healthy volunteers during the waking state (baseline) and during propofol anaesthesia. Propofol was titrated to keep a constant hypnotic depth (Bispectral Indes 35-40) throughout the anaesthesia. Changes in rGMR and rCBF were quantified using region-of-interest and voxel-based analyses. RESULTS The measured mean propofol concentration was 4.1 ± 0.8 μg/ml during anaesthesia. Compared with the conscious state, total CBF and GMR decreased during the anaesthetic state with 47% and 54%, respectively. In the white and grey matter, rCBF and rGMR were reduced by 37% and 49%, and by 45% and 57%, respectively. Propofol decreased rCBF in all brain structures by 46-55% (P ≤ 0.01) with highest significant decreases in the thalamus and parietal lobe. Regional GMR was reduced in all brain areas to 48-66% (P ≤ 0.01) with highest significant reductions in the occipital lobe, the lingual gyrus, parietal lobe, temporal lobe and thalamus. No increases in rCBF or rGMR happened anywhere. CONCLUSIONS General anaesthesia with propofol is associated with a global metabolic and vascular depression in the human brain, with significant shifts in regional blood flow and metabolism indicating marked metabolic and vascular responsiveness in some cortical areas and thalamus.
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Affiliation(s)
- L. SCHLÜNZEN
- Department of Neuroanaesthesiology; Aarhus University Hospitals; Aarhus; Denmark
| | - N. JUUL
- Department of Neuroanaesthesiology; Aarhus University Hospitals; Aarhus; Denmark
| | - K. V. HANSEN
- Department of PET Centre; Aarhus University Hospitals; Aarhus; Denmark
| | - G. E. COLD
- Department of Neuroanaesthesiology; Aarhus University Hospitals; Aarhus; Denmark
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Xie G, Deschamps A, Backman S, Fiset P, Chartrand D, Dagher A, Plourde G. Critical involvement of the thalamus and precuneus during restoration of consciousness with physostigmine in humans during propofol anaesthesia: a positron emission tomography study. Br J Anaesth 2011; 106:548-57. [DOI: 10.1093/bja/aeq415] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Changes in resting neural connectivity during propofol sedation. PLoS One 2010; 5:e14224. [PMID: 21151992 PMCID: PMC2996305 DOI: 10.1371/journal.pone.0014224] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Accepted: 11/04/2010] [Indexed: 11/24/2022] Open
Abstract
Background The default mode network consists of a set of functionally connected brain regions (posterior cingulate, medial prefrontal cortex and bilateral parietal cortex) maximally active in functional imaging studies under “no task” conditions. It has been argued that the posterior cingulate is important in consciousness/awareness, but previous investigations of resting interactions between the posterior cingulate cortex and other brain regions during sedation and anesthesia have produced inconsistent results. Methodology/Principal Findings We examined the connectivity of the posterior cingulate at different levels of consciousness. “No task” fMRI (BOLD) data were collected from healthy volunteers while awake and at low and moderate levels of sedation, induced by the anesthetic agent propofol. Our data show that connectivity of the posterior cingulate changes during sedation to include areas that are not traditionally considered to be part of the default mode network, such as the motor/somatosensory cortices, the anterior thalamic nuclei, and the reticular activating system. Conclusions/Significance This neuroanatomical signature resembles that of non-REM sleep, and may be evidence for a system that reduces its discriminable states and switches into more stereotypic patterns of firing under sedation.
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Relationship between regional cerebral blood flow and electrocorticographic activities under sevoflurane and isoflurane anesthesia. J Clin Neurophysiol 2010; 27:110-5. [PMID: 20505374 DOI: 10.1097/wnp.0b013e3181d64da1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The aims of this study are (1) to assess the effects of volatile anesthetics on regional cerebral blood flow (rCBF) and electrocorticography (ECoG), and (2) to investigate the relationship between rCBF and ECoG influenced by volatile anesthetics. The authors measured rCBF using laser Doppler flowmetry and ECoG simultaneously and continuously from the same cortex during craniotomy, using the specially arranged probe. Patients received intravenous anesthetics with nitrous oxide until craniotomy, and after opening of dura, volatile anesthetic, either isoflurane or sevoflurane, was started and was gradually increased for the measurement. Four of the nine cases (44.4%) of the sevoflurane group showed no change both in rCBF and ECoG. In three cases (33.3%), rCBF increased as the frequency of the paroxysmal activities increased. In two cases (22.2%), decreased rCBF was accompanied by slow waves. In 12 cases of the isoflurane group, no apparent rCBF and ECoG changes were seen, except a case with decreased rCBF and slow waves. This is the first report of simultaneous recordings of regional CBF and neuronal activity under general anesthesia. During sevoflurane and isoflurane anesthesia <2.5 minimum alveolar anesthetic concentration, rCBF is affected by ECoG activities rather than pharmacologic action of inhalational anesthetics.
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Martuzzi R, Ramani R, Qiu M, Rajeevan N, Constable RT. Functional connectivity and alterations in baseline brain state in humans. Neuroimage 2009; 49:823-34. [PMID: 19631277 DOI: 10.1016/j.neuroimage.2009.07.028] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Revised: 07/10/2009] [Accepted: 07/15/2009] [Indexed: 11/18/2022] Open
Abstract
This work examines the influence of changes in baseline activity on the intrinsic functional connectivity fMRI (fc-fMRI) in humans. Baseline brain activity was altered by inducing anesthesia (sevoflurane end-tidal concentration 1%) in human volunteers and fc-fMRI maps between the pre-anesthetized and anesthetized conditions were compared across different brain networks. We particularly focused on low-level sensory areas (primary somatosensory, visual, and auditory cortices), the thalamus, and pain (insula), memory (hippocampus) circuits, and the default mode network (DMN), the latter three to examine higher-order brain regions. The results indicate that, while fc-fMRI patterns did not significantly differ (p<0.005; 20-voxel cluster threshold) in sensory cortex and in the DMN between the pre- and anesthetized conditions, fc-fMRI in high-order cognitive regions (i.e. memory and pain circuits) was significantly altered by anesthesia. These findings provide further evidence that fc-fMRI reflects intrinsic brain properties, while also demonstrating that 0.5 MAC sevoflurane anesthesia preferentially modulates higher-order connections.
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Affiliation(s)
- Roberto Martuzzi
- Department of Diagnostic Radiology, Yale University School of Medicine, The Anlyan Center, 300 Cedar Street, New Haven, CT 06520-8042, USA.
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Qiu M, Ramani R, Swetye M, Constable RT. Spatial nonuniformity of the resting CBF and BOLD responses to sevoflurane: in vivo study of normal human subjects with magnetic resonance imaging. Hum Brain Mapp 2009; 29:1390-9. [PMID: 17948882 DOI: 10.1002/hbm.20472] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pulsed arterial spin labeling magnetic resonance imaging (MRI) was performed to investigate the local coupling between resting regional cerebral blood flow (rCBF) and BOLD (blood oxygen level dependent) signal changes in 22 normal human subjects during the administration of 0.25 MAC (minimum alveolar concentration) sevoflurane. Two states were compared with subjects at rest: anesthesia and no-anesthesia. Regions of both significantly increased and decreased resting-state rCBF were observed. Increases were limited primarily to subcortical structures and insula, whereas, decreases were observed primarily in neocortical regions. No significant change was found in global CBF (gCBF). By simultaneously measuring rCBF and BOLD, region-specific anesthetic effects on the coupling between rCBF and BOLD were identified. Multiple comparisons of the agent-induced rCBF and BOLD changes demonstrated significant (P < 0.05) spatial variability in rCBF-BOLD coupling. The slope of the linear regression line for AC, where rCBF was increased by sevoflurane, was markedly smaller than the slope for those ROIs where rCBF was decreased by sevoflurane, indicating a bigger change in BOLD per unit change in rCBF in regions where rCBF was increased by sevoflurane. These results suggest that it would be inaccurate to use a global quantitative model to describe coupling across all brain regions and in all anesthesia conditions. The observed spatial nonuniformity of rCBF and BOLD signal changes suggests that any interpretation of BOLD fMRI data in the presence of an anesthetic requires consideration of these insights.
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Affiliation(s)
- Maolin Qiu
- Department of Diagnostic Radiology, Yale University School of Medicine, The Anlyan Center N128, New Haven, Connecticut 06520-8042, USA.
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Abstract
PURPOSE OF REVIEW This review will highlight the recent functional magnetic resonance imaging, positron emission tomogram scan and connectivity studies in anesthesia and analgesia. RECENT FINDINGS In regional cerebral blood flow (rCBF) studies with isoflurane and sevoflurane, there is a consistent pattern of rise in rCBF in the anterior cingulate cortex and insula while the thalamus, lingual cortex and cerebellum show a decrease in rCBF, in a dose range of 0.2-1 minimum alveolar concentration. Even 0.25 minimum alveolar concentration causes a predominant decrease of rCBF in the cortical regions and increase of rCBF in the subcortical regions. This minimum alveolar concentration level primarily affects the association cortices. Thalamus and thalamo-cortical pathways seem to be linked to the hypnotic effects of anesthesia and deep sedation. Connectivity studies also confirm this. The electroencephalogram equivalent of this appears to be a transition from 'alpha' wave activity to 'delta' wave activity. Anterior cingulate cortex, S1 and S2 are the regions consistently activated in acute pain. Remifentanil infusion in acute pain decreases the activation in pain perception regions while activating the pain modulation regions. In chronic pain states, prefrontal cortex and insula are activated whereas there is a decrease in activity in the thalamus. SUMMARY Slowly, a pattern of neuronal activity reflecting hypnosis, analgesia, amnesia and reflex suppression seems to be emerging giving us a better insight into the central nervous system effects of anesthesia.
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Ramani R, Qiu M, Constable RT. Sevoflurane 0.25 MAC preferentially affects higher order association areas: a functional magnetic resonance imaging study in volunteers. Anesth Analg 2007; 105:648-55. [PMID: 17717218 PMCID: PMC2716177 DOI: 10.1213/01.ane.0000277496.12747.29] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Functional magnetic resonance imaging (fMRI) can objectively measure the subjective effects of anesthesia. Memory-related regions (association areas) are affected by subanesthetic doses of volatile anesthetics. In this study we measured the regional neuronal effects of 0.25 MAC sevoflurane in healthy volunteers and differentiated the effect between primary cortical regions and association areas. METHODS The effect of 0.25 MAC sevoflurane on visual, auditory, and motor activation was studied in 16 ASA I volunteers. With fMRI (3 Tesla Siemens magnetom), regional cerebral blood flow (rCBF) was measured by the pulsed arterial spin labeling technique. Subjects inhaled a mixture of O2 and 0.25 MAC sevoflurane and standard ASA monitoring was performed. Visual, auditory, and motor activation tasks were used. rCBF was measured in the awake state and during inhalation of 0.25 MAC sevoflurane, without and with activation. The change in rCBF (deltaCBF) with 0.25 MAC Sevoflurane during baseline state and with activation was calculated in 11 regions of interest related to visual, auditory, and motor activation tasks. RESULTS The change from baseline rCBF with 0.25 MAC sevoflurane was not statistically significant in the 11 regions of interest. With activation there was a significant increase in CBF in several regions. However, only in the primary and secondary visual cortices (V1, V2), thalamus, hippocampus, and supplementary motor area was the decrease in activation with 0.25 MAC sevoflurane statistically significant (P < 0.05). CONCLUSION Memory-related regions (association areas) are affected by subanesthetic concentrations of volatile anesthetics. Using fMRI, this study showed that 0.25 MAC sevoflurane predominantly affects the primary visual cortex, the related association cortex, and certain other higher order association cortices.
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Affiliation(s)
- Ramachandran Ramani
- Department of Anesthesia, Yale University School of Medicine, New Haven, CT 06520-8051, USA.
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Ishizawa Y. Mechanisms of anesthetic actions and the brain. J Anesth 2007; 21:187-99. [PMID: 17458649 DOI: 10.1007/s00540-006-0482-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Accepted: 11/09/2006] [Indexed: 11/25/2022]
Abstract
The neural mechanisms behind anesthetic-induced behavioral changes such as loss of consciousness, amnesia, and analgesia, are insufficiently understood, though general anesthesia has been of tremendous importance for the development of medicine. In this review, I summarize what is currently known about general anesthetic actions at different organizational levels and discuss current and future research, using systems neuroscience approaches such as functional neuroimaging and quantitative electrophysiology to understand anesthesia actions at the integrated brain level.
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Affiliation(s)
- Yumiko Ishizawa
- Department of Anesthesia and Critical Care, Massachusetts General Hospital, 55 Fruit Street, Clinics 3, Boston, MA 02114, USA
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Randell T, Niskanen M. Management of physiological variables in neuroanaesthesia: maintaining homeostasis during intracranial surgery. Curr Opin Anaesthesiol 2007; 19:492-7. [PMID: 16960480 DOI: 10.1097/01.aco.0000245273.92163.8e] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW The recent literature on the perioperative maintenance of cerebral homeostasis was reviewed. RECENT FINDINGS Several studies focused on the regulation of cerebral blood flow in patients without intracranial disease; therefore, further studies in neurosurgical patients are needed. High intracranial pressure and brain swelling can be controlled by the choice of anaesthetic agents, and also by optimal positioning of the patient. The use of positive end-expiratory pressure may impair cerebral blood flow, but the effects of positive end-expiratory pressure seem to depend on the respiratory system compliance. The international multicenter study failed to show any benefit from intraoperative hypothermia in patients with subarachnoid hemorrhage; similarly, the results on corticosteroid therapy in head-injured patients are discouraging. Corticosteroid therapy has prompted studies on the control of blood glucose levels. While tight glycemic control has been recommended, it can have untoward effects manifested as cerebral metabolic stress. SUMMARY From the clinical point of view, the recent research has added only little to the knowledge on the management of physiological parameters in neurosurgery. More adequately powered studies focusing in specific problems, and having a meaningful aim relative to outcome, are needed also in neuroanaesthesia.
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Affiliation(s)
- Tarja Randell
- Department of Anaesthesia and Intensive Care, Helsinki University Hospital, Helsinki, Finland.
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Molnár C, Settakis G, Sárkány P, Kálmán S, Szabó S, Fülesdi B. Effect of sevoflurane on cerebral blood flow and cerebrovascular resistance at surgical level of anaesthesia: a transcranial Doppler study. Eur J Anaesthesiol 2006; 24:179-84. [PMID: 16970835 DOI: 10.1017/s0265021506001335] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2006] [Indexed: 11/08/2022]
Abstract
BACKGROUND AND OBJECTIVE It is widely accepted that sevoflurane affects cerebral circulation, but there are uncertainities regarding the magnitude of its effect. The aim of the present work was to assess the effect of sevoflurane on the cerebral circulation at surgical levels of anaesthesia. METHODS Twenty patients undergoing elective lumbar discectomies were investigated. Anaesthesia was induced with propofol and maintained with sevoflurane. The level of surgical anaesthesia was determined by bispectral index, the target level was 45-55. Transcranial Doppler (TCD) measurement was performed before induction and after reaching the surgical level of anaesthesia. Besides routine parameters (middle cerebral artery mean blood flow velocity (MCAV) and pulsatility index (PI)) derived parameters (estimated cerebral perfusion pressure (eCPP), cerebral blood flow index (CBFI) and resistance area product (RAP)) were calculated by taking changes of mean arterial pressure also into account. RESULTS MCAV decreased from 54.1 +/- 13.3 to 43.7 +/- 18.5 cm s-1, P < 0.01 and PI increased from 0.79 +/- 0.2 to 0.92 +/- 0.2, P < 0.01 after reaching the surgical level of anaesthesia. As a result eCPP decreased by 18.2%, CBFI by 25.5% and RAP increased by 15% respectively. CONCLUSIONS Our data indicate a vasodilatory effect of sevoflurane at surgical level of anaesthesia on large cerebral vessels or a vasoconstriction of the resistance arterioles likely caused by decreased brain metabolism.
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Affiliation(s)
- C Molnár
- Department of Anesthesiology and Intensive Care, Health and Medical Science Centre, University of Debrecen, Nagyerdei krt. 98, H-4012 Debrecen, Hungary
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Fassoulaki A, Kaliontzi H, Petropoulos G, Tsaroucha A. The Effect of Desflurane and Sevoflurane on Cerebral Oximetry Under Steady-State Conditions. Anesth Analg 2006; 102:1830-5. [PMID: 16717333 DOI: 10.1213/01.ane.0000205739.37190.14] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We studied the effect of sevoflurane and desflurane on regional cerebral oxygenation (rSO2). Twenty-two patients undergoing abdominal hysterectomy received sevoflurane and desflurane for 15 min each and 30 min apart under steady-state conditions in a randomized, crossover manner to maintain a bispectral index (BIS) of 40-50. In another 22 patients undergoing the same anesthesia and surgery BIS was maintained at 20-30. During the 15-min administration of each anesthetic at steady-state conditions rSO2, BIS, inspired and end-tidal anesthetic concentrations, end-tidal CO2, Spo2, systolic and diastolic blood pressures, and heart rate were recorded every 3 min. The rSO2 did not differ between sevoflurane and desflurane when BIS values were maintained between 40-50 or 20-30. The MAC(BIS) values required to maintain BIS at 40-50 and at 20-30 were 1.0 versus 1.2 (P = 0.004) and 1.6 versus 1.8 (P < 0.001) for desflurane and sevoflurane respectively. Higher rSO2 values were obtained by 1.6 MAC (71 +/- 13) than by 1 MAC of desflurane (66 +/- 10; P < 0.001) and by 1.8 MAC (72 +/- 11) than by 1.2 MAC of sevoflurane (66 +/- 13; P < 0.001). In conclusion, equipotent concentrations of desflurane or sevoflurane in terms of BIS are associated with similar rSO2 values, but larger anesthetic concentrations of both anesthetics increased the rSO2 values.
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Schlünzen L, Cold GE, Rasmussen M, Vafaee MS. Effects of dose-dependent levels of isoflurane on cerebral blood flow in healthy subjects studied using positron emission tomography. Acta Anaesthesiol Scand 2006; 50:306-12. [PMID: 16480463 DOI: 10.1111/j.1399-6576.2006.00954.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND In this study, we tested the hypothesis that escalating drug concentrations of isoflurane are associated with a significant decline in cerebral blood flow (CBF) in regions sub-serving conscious brain activity, including specifically the thalamus. METHODS Nine human volunteers received three escalating drug concentrations: 0.2, 0.4 and 1.0 MAC end-tidal inhalation. During waking, baseline and the three levels of sedation, aO PET scan was performed. RESULTS Isoflurane decreased the bispectral index (BIS) values dose-dependently. Cardiovascular and respiratory parameters were maintained constant over time. No significant change in global CBF was observed. Throughout all three MAC levels of sedation, isoflurane caused an increased regional cerebral blood flow (rCBF) in the anterior cingulate and decreased rCBF in the cerebellum. Initially, isoflurane (0 vs. 0.2 MAC) significantly increased relative rCBF in the medial frontal gyrus and in the nucleus accumbens. At the next level (0.2 vs. 0.4 MAC), relative rCBF was significantly increased in the caudate nucleus and decreased in the lingual gyrus and cuneus. At the last level (0.4 vs. 1 MAC), relative rCBF was significantly increased in the insula and decreased in the thalamus, the cuneus and lingual gyrus. Compared with flow distribution in awake volunteers, 1 MAC of isoflurane significantly raised relative activity in the anterior cingulate and insula regions. In contrast, a significant relative flow reduction was identified in the thalamus, the cerebellum and lingual gyrus. CONCLUSIONS Isoflurane, like sevoflurane, induced characteristic flow redistribution at doses of 0.2-1.0 MAC. At 1 MAC of isoflurane, rCBF decreased in the thalamus. Specific areas affected by both isoflurane and sevoflurane included the anterior cingulate, insula regions, cerebellum, lingual gyrus and thalamus.
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Affiliation(s)
- L Schlünzen
- Department of Neuroanaesthesiology, Aarhus University Hospital, Aarhus, Denmark.
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Volkow ND, Wang GJ, Franceschi D, Fowler JS, Thanos PPK, Maynard L, Gatley SJ, Wong C, Veech RL, Kunos G, Kai Li T. Low doses of alcohol substantially decrease glucose metabolism in the human brain. Neuroimage 2006; 29:295-301. [PMID: 16085426 DOI: 10.1016/j.neuroimage.2005.07.004] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Revised: 06/30/2005] [Accepted: 07/04/2005] [Indexed: 11/20/2022] Open
Abstract
Moderate doses of alcohol decrease glucose metabolism in the human brain, which has been interpreted to reflect alcohol-induced decreases in brain activity. Here, we measure the effects of two relatively low doses of alcohol (0.25 g/kg and 0.5 g/kg, or 5 to 10 mM in total body H2O) on glucose metabolism in the human brain. Twenty healthy control subjects were tested using positron emission tomography (PET) and FDG after placebo and after acute oral administration of either 0.25 g/kg, or 0.5 g/kg of alcohol, administered over 40 min. Both doses of alcohol significantly decreased whole-brain glucose metabolism (10% and 23% respectively). The responses differed between doses; whereas the 0.25 g/kg dose predominantly reduced metabolism in cortical regions, the 0.5 g/kg dose reduced metabolism in cortical as well as subcortical regions (i.e. cerebellum, mesencephalon, basal ganglia and thalamus). These doses of alcohol did not significantly change the scores in cognitive performance, which contrasts with our previous results showing that a 13% reduction in brain metabolism by lorazepam was associated with significant impairment in performance on the same battery of cognitive tests. This seemingly paradoxical finding raises the possibility that the large brain metabolic decrements during alcohol intoxication could reflect a shift in the substrate for energy utilization, particularly in light of new evidence that blood-borne acetate, which is markedly increased during intoxication, is a substrate for energy production by the brain.
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Affiliation(s)
- Nora D Volkow
- National Institute on Drug Abuse, 6001 Executive Blvd., Room 5274, Bethesda, MD 20892, USA.
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Heinke W, Koelsch S. The effects of anesthetics on brain activity and cognitive function. Curr Opin Anaesthesiol 2005; 18:625-31. [PMID: 16534303 DOI: 10.1097/01.aco.0000189879.67092.12] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE OF THIS REVIEW This review presents an overview of recent findings related to changes in brain activity with increasing anesthesia mainly obtained with brain imaging and electrophysiological techniques in humans. RECENT FINDINGS Recent studies have revealed that the brain as a whole is not affected to the same degree by anesthetics, but that specific brain regions (and particular cognitive processes mediated by these regions) are more sensitive to anesthesia and sedation than others. Inhibition of activity in multimodal association cortices (such as parietal and prefrontal association cortices) by sedative concentrations of anesthetics produces amnesia and attention deficits, whereas activity in unimodal cortices and in the thalamus remains largely unaffected by low doses of anesthetics. Activity in the midbrain reticular formation, thalamus, and unimodal cortices appears to be suppressed only by anesthetic concentrations causing unconsciousness. Besides those regional suppressive effects, anesthetics impair functional connections between neurons in distributed cortical and thalamocortical networks, which also contributes to the state of anesthesia. SUMMARY Anesthetics produce changes in the patient's behavioral state by interacting with brain activity via at least two mechanisms: the dose-dependent global and regionally specific suppression of neuronal activity and the disruption of functional interactivity within distributed neural networks.
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Affiliation(s)
- Wolfgang Heinke
- Department of Anesthesiology and Intensive Care Therapy, University of Leipzig, Leipzig, Germany.
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Lorenz IH, Kolbitsch C. Sevoflurane and CBF: there is much more out there than you might expect. Acta Anaesthesiol Scand 2005; 49:1222. [PMID: 16095468 DOI: 10.1111/j.1399-6576.2005.00768.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Alkire MT, Miller J. General anesthesia and the neural correlates of consciousness. PROGRESS IN BRAIN RESEARCH 2005; 150:229-44. [PMID: 16186027 DOI: 10.1016/s0079-6123(05)50017-7] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The neural correlates of consciousness must be identified, but how? Anesthetics can be used as tools to dissect the nervous system. Anesthetics not only allow for the experimental investigation into the conscious-unconscious state transition, but they can also be titrated to subanesthetic doses in order to affect selected components of consciousness such as memory, attention, pain processing, or emotion. A number of basic neuroimaging examinations of various anesthetic agents have now been completed. A common pattern of regional activity suppression is emerging for which the thalamus is identified as a key target of anesthetic effects on consciousness. It has been proposed that a neuronal hyperpolarization block at the level of the thalamus, or thalamocortical and corticocortical reverberant loops, could contribute to anesthetic-induced unconsciousness. However, all anesthetics do not suppress global cerebral metabolism and cause a regionally specific effect on thalamic activity. Ketamine, a so-called dissociative anesthetic agent, increases global cerebral metabolism in humans at doses associated with a loss of consciousness. Nevertheless, it is proposed that those few anesthetics not associated with a global metabolic suppression effect might still have their effects on consciousness mediated at the level of thalamocortical interactions, if such agents scramble the signals associated with normal neuronal network reverberant activity. Functional and effective connectivity are analysis techniques that can be used with neuroimaging to investigate the signal scrambling effects of various anesthetics on network interactions. Whereas network interactions have yet to be investigated with ketamine, a thalamocortical and corticocortical disconnection effect during unconsciousness has been found for both suppressive anesthetic agents and for patients who are in the persistent vegetative state. Furthermore, recovery from a vegetative state is associated with a reconnection of functional connectivity. Taken together these intriguing observations offer strong empirical support that the thalamus and thalamocortical reverberant network loop interactions are at the heart of the neurobiology of consciousness.
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Affiliation(s)
- Michael T Alkire
- Department of Anesthesiology and The Center for the Neurobiology of Learning and Memory, University of California at Irvine, Irvine, CA, USA.
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