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Foo CT, Langton D, Thompson BR, Thien F. Functional lung imaging using novel and emerging MRI techniques. Front Med (Lausanne) 2023; 10:1060940. [PMID: 37181360 PMCID: PMC10166823 DOI: 10.3389/fmed.2023.1060940] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 04/03/2023] [Indexed: 05/16/2023] Open
Abstract
Respiratory diseases are leading causes of death and disability in the world. While early diagnosis is key, this has proven difficult due to the lack of sensitive and non-invasive tools. Computed tomography is regarded as the gold standard for structural lung imaging but lacks functional information and involves significant radiation exposure. Lung magnetic resonance imaging (MRI) has historically been challenging due to its short T2 and low proton density. Hyperpolarised gas MRI is an emerging technique that is able to overcome these difficulties, permitting the functional and microstructural evaluation of the lung. Other novel imaging techniques such as fluorinated gas MRI, oxygen-enhanced MRI, Fourier decomposition MRI and phase-resolved functional lung imaging can also be used to interrogate lung function though they are currently at varying stages of development. This article provides a clinically focused review of these contrast and non-contrast MR imaging techniques and their current applications in lung disease.
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Affiliation(s)
- Chuan T. Foo
- Department of Respiratory Medicine, Eastern Health, Melbourne, VIC, Australia
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia
| | - David Langton
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia
- Department of Thoracic Medicine, Peninsula Health, Frankston, VIC, Australia
| | - Bruce R. Thompson
- Melbourne School of Health Science, Melbourne University, Melbourne, VIC, Australia
| | - Francis Thien
- Department of Respiratory Medicine, Eastern Health, Melbourne, VIC, Australia
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia
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Lisichenko IA, Gusarov VG, Teplykh BA, Chayanov NV, Zamyatin MN. Assessment of Amnesic Effect and the Depth of Hypnosis During Therapeutic Inhalation of Xenon-Oxygen Mixture. MESSENGER OF ANESTHESIOLOGY AND RESUSCITATION 2022. [DOI: 10.21292/2078-5658-2022-19-5-19-27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/17/2023]
Abstract
The current literature lacks data on the incidence of intraoperative awakening during xenon anesthesia. This could be due to amnesia preventing memories of the intraoperative awakening.The objective: to determine the concentration of xenon in the xenon-oxygen mixture, which causes amnesia for events during inhalation in 100% of patients, and to make correlations with the depth of hypnosis as per Kugler scale.Subjects and Methods: 34 patients with chronic neurogenic pain who received 111 20-minute inhalations with concentration of xenon up to 50% were included in the study. Amnesia evaluation, EEG monitoring, and pain assessment on a visual analog scale (VAS) were performed.Results. Amnesic effect developed in 100% of patients at xenon concentration of 45%. On inhalation of xenon at concentrations of up to 50%, EEG changes did not exceed D1 grade on Kugler scale. The decrease in bispectral index (BIS) did not reach the level of deep sedation (Me 96.2%) at xenon concentration of 50%. The decrease in pain on VAS was approximately 60%.Conclusions. Xenon inhalations cause transient congradic amnesia at concentrations of 45% or more. The accuracy of the BIS monitoring readings may be reduced when using xenon in a monovariant. Inhalations of xenon-oxygen mixture in concentrations up to 50% showed good analgesic properties in the framework of combined therapy of chronic pain syndrome.
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Stewart NJ, Smith LJ, Chan HF, Eaden JA, Rajaram S, Swift AJ, Weatherley ND, Biancardi A, Collier GJ, Hughes D, Klafkowski G, Johns CS, West N, Ugonna K, Bianchi SM, Lawson R, Sabroe I, Marshall H, Wild JM. Lung MRI with hyperpolarised gases: current & future clinical perspectives. Br J Radiol 2022; 95:20210207. [PMID: 34106792 PMCID: PMC9153706 DOI: 10.1259/bjr.20210207] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The use of pulmonary MRI in a clinical setting has historically been limited. Whilst CT remains the gold-standard for structural lung imaging in many clinical indications, technical developments in ultrashort and zero echo time MRI techniques are beginning to help realise non-ionising structural imaging in certain lung disorders. In this invited review, we discuss a complementary technique - hyperpolarised (HP) gas MRI with inhaled 3He and 129Xe - a method for functional and microstructural imaging of the lung that has great potential as a clinical tool for early detection and improved understanding of pathophysiology in many lung diseases. HP gas MRI now has the potential to make an impact on clinical management by enabling safe, sensitive monitoring of disease progression and response to therapy. With reference to the significant evidence base gathered over the last two decades, we review HP gas MRI studies in patients with a range of pulmonary disorders, including COPD/emphysema, asthma, cystic fibrosis, and interstitial lung disease. We provide several examples of our experience in Sheffield of using these techniques in a diagnostic clinical setting in challenging adult and paediatric lung diseases.
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Affiliation(s)
- Neil J Stewart
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Laurie J Smith
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Ho-Fung Chan
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - James A Eaden
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Smitha Rajaram
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Andrew J Swift
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Nicholas D Weatherley
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Alberto Biancardi
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Guilhem J Collier
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - David Hughes
- Sheffield Children's NHS Foundation Trust, Sheffield, UK
| | | | - Christopher S Johns
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
| | - Noreen West
- Sheffield Children's NHS Foundation Trust, Sheffield, UK
| | - Kelechi Ugonna
- Sheffield Children's NHS Foundation Trust, Sheffield, UK
| | - Stephen M Bianchi
- Directorate of Respiratory Medicine, Sheffield Teaching Hospitals NHS Trust, Sheffield, UK
| | - Rod Lawson
- Directorate of Respiratory Medicine, Sheffield Teaching Hospitals NHS Trust, Sheffield, UK
| | - Ian Sabroe
- Directorate of Respiratory Medicine, Sheffield Teaching Hospitals NHS Trust, Sheffield, UK
| | - Helen Marshall
- POLARIS, Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, UK
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Jin Z, Hu J, Ma D. Postoperative delirium: perioperative assessment, risk reduction, and management. Br J Anaesth 2020; 125:492-504. [DOI: 10.1016/j.bja.2020.06.063] [Citation(s) in RCA: 232] [Impact Index Per Article: 58.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/22/2020] [Accepted: 06/20/2020] [Indexed: 12/20/2022] Open
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Lawley JS, Gatterer H, Dias KA, Howden EJ, Sarma S, Cornwell WK, Hearon CM, Samels M, Everding B, Bruick RK, Hendrix M, Piper T, Thevis M, Levine BD. Safety, hemodynamic effects, and detection of acute xenon inhalation: rationale for banning xenon from sport. J Appl Physiol (1985) 2019; 127:1511-1518. [DOI: 10.1152/japplphysiol.00290.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
This study aimed to quantify the sedative effects, detection rates, and cardiovascular responses to xenon. On 3 occasions, participants breathed xenon (FiXe 30% for 20 min; FiXe 50% for 5 min; FiXe 70% for 2 min) in a nonblinded design. Sedation was monitored by a board-certified anesthesiologist. During 70% xenon, participants were also verbally instructed to operate a manual value with time-to-task failure being recorded. Beat-by-beat hemodynamics were measured continuously by ECG, photoplethysmography, and transcranial Doppler. Over 48 h postadministration, xenon was measured in blood and urine by gas chromatography-mass spectrometry. Xenon caused variable levels of sedation and restlessness. Task failure of the self-operating value occurred at 60–90 s in most individuals. Over the first minute, 50% and 70% xenon caused a substantial reduction in total peripheral resistance ( P < 0.05). All dosages caused an increase in cardiac output ( P < 0.05). By the end of xenon inhalation, slight hypertension was observed after all three doses ( P < 0.05), with an increase in middle cerebral artery velocity ( P < 0.05). Xenon was consistently detected, albeit in trace amounts, up to 3 h after all three doses of xenon inhalation in blood and urine with variable results thereafter. Xenon inhalation caused sedation incompatible with self-operation of a breathing apparatus, thus causing a potential life-threatening condition in the absence of an anesthesiologist. Yet, xenon can only be reliably detected in blood and urine up to 3 h postacute dosing. NEW & NOTEWORTHY Breathing xenon in dosages conceivable for doping purposes (FiXe 30% for 20 min; FiXe 50% for 5 min; FiXe 70% for 2 min) causes an initial rapid fall in total peripheral resistance with tachycardia and thereafter a mild hypertension with elevated middle cerebral artery velocity. These dose duration intervals cause sedation that is incompatible with operating a breathing apparatus and can only be detected in blood and urine samples with a high probability for up to ~3 h.
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Affiliation(s)
- Justin S. Lawley
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas
- University of Texas Southwestern Medical Center, Dallas, Texas
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Hannes Gatterer
- Institute of Mountain Emergency Medicine, EURAC Research, Bolzano, Italy
| | - Katrin A. Dias
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas
- University of Texas Southwestern Medical Center, Dallas, Texas
| | - Erin J. Howden
- The Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Satyam Sarma
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas
- University of Texas Southwestern Medical Center, Dallas, Texas
| | | | - Christopher M. Hearon
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas
- University of Texas Southwestern Medical Center, Dallas, Texas
| | - Mitchel Samels
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas
| | - Braden Everding
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas
| | | | - Max Hendrix
- University of Texas Southwestern Medical Center, Dallas, Texas
| | - Thomas Piper
- German Sport University Cologne, Institute of Biochemistry/Center for Preventive Doping Research, Cologne, Germany
| | - Mario Thevis
- German Sport University Cologne, Institute of Biochemistry/Center for Preventive Doping Research, Cologne, Germany
| | - Benjamin D. Levine
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas, Dallas, Texas
- University of Texas Southwestern Medical Center, Dallas, Texas
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Zhao CS, Li H, Wang Z, Chen G. Potential application value of xenon in stroke treatment. Med Gas Res 2018; 8:116-120. [PMID: 30319767 PMCID: PMC6178644 DOI: 10.4103/2045-9912.241077] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 08/03/2018] [Indexed: 11/04/2022] Open
Abstract
Stroke is an acute disease with extremely high mortality and disability, including ischemic stroke and hemorrhagic stroke. Currently only limited drugs and treatments have been shown to have neuroprotective effects in stroke. As a medical gas, xenon has been proven to have neuroprotective effect in considerable amount of previous study. Its unique properties are different from other neuroprotective agents, making it is promising to play a special therapeutic role in stroke, either alone or in combination with other treatments. In this article, we aim to review the role of xenon in the treatment of stroke, and summarize the mechanism of using xenon to produce therapeutic effects after stroke according to the existing research. Moreover, we intend to explore and demonstrate the feasibility and safety of xenon for clinical treatment of stroke. Despite the disadvantages of difficulty in obtaining and being expensive, as long as the use of reasonable methods, xenon can play an important role in the treatment of stroke.
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Affiliation(s)
- Chong-Shun Zhao
- Department of Neurosurgery & Brain and Nerve Research Laboratory, the First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
| | - Hao Li
- Department of Neurology, the First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
| | - Zhong Wang
- Department of Neurosurgery & Brain and Nerve Research Laboratory, the First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
| | - Gang Chen
- Department of Neurosurgery & Brain and Nerve Research Laboratory, the First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China
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Jin Z, Piazza O, Ma D, Scarpati G, De Robertis E. Xenon anesthesia and beyond: pros and cons. Minerva Anestesiol 2018; 85:83-89. [PMID: 30019577 DOI: 10.23736/s0375-9393.18.12909-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Xenon is a colorless and odorless noble gas, licensed for human use as an anesthetic gas as well as a radiological marker. The MAC of this gas is about 63% but xenon anesthesia is associated with fast recovery of cognitive function and cardiovascular stability. Nevertheless, postoperative nausea and vomiting (PONV) incidence for xenon anesthesia is very high. It has been reported that Xenon has cytoprotective effects that may have therapeutic values in both CNS protection, and in organ graft preservation. Currently, there are few studies about the effect of xenon on ischemia reperfusion injury of transplantable organs and insufficient clinical data upon its effect on intracranial and cerebral perfusion pressure. We shortly review the pros and cons of xenon as an anesthetic agent.
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Affiliation(s)
- Zhaosheng Jin
- Anesthetics, Pain Medicine, and Intensive Care, Department of Surgery and Cancer, Imperial College London, Chelsea and Westminster Hospital, London, UK
| | - Ornella Piazza
- Department of Medicine and Surgery, University of Salerno, Salerno, Italy
| | - Daqing Ma
- Anesthetics, Pain Medicine, and Intensive Care, Department of Surgery and Cancer, Imperial College London, Chelsea and Westminster Hospital, London, UK
| | - Giuliana Scarpati
- Department of Medicine and Surgery, University of Salerno, Salerno, Italy
| | - Edoardo De Robertis
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, Federico II University, Naples, Italy -
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Deng HB, Li FX, Cai YH, Xu SY. Waste anesthetic gas exposure and strategies for solution. J Anesth 2018; 32:269-282. [PMID: 29404778 DOI: 10.1007/s00540-018-2448-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2017] [Accepted: 01/02/2018] [Indexed: 12/15/2022]
Abstract
As inhaled anesthetics are widely used, medical staff have inevitably suffered from exposure to anesthetic waste gases (WAGs). Whether chronic exposure to WAGs has an impact on the health of medical staff has long been a common concern, but conclusions are not consistent. Many measures and equipment have been proposed to reduce the concentration of WAGs as far as possible. This review aims to dissect the current exposure to WAGs and its influence on medical staff in the workplace and the environment, and summarize strategies to reduce WAGs.
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Affiliation(s)
- Hai-Bo Deng
- Department of Anesthesiology, Zhujiang Hospital of Southern Medical University, 253 Gongye Ave, Guangzhou, 510282, China
| | - Feng-Xian Li
- Department of Anesthesiology, Zhujiang Hospital of Southern Medical University, 253 Gongye Ave, Guangzhou, 510282, China
| | - Ye-Hua Cai
- Department of Anesthesiology, Zhujiang Hospital of Southern Medical University, 253 Gongye Ave, Guangzhou, 510282, China.
| | - Shi-Yuan Xu
- Department of Anesthesiology, Zhujiang Hospital of Southern Medical University, 253 Gongye Ave, Guangzhou, 510282, China.
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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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Al tmimi L, Devroe S, Dewinter G, Van de Velde M, Poortmans G, Meyns B, Meuris B, Coburn M, Rex S. Xenon as an Adjuvant to Propofol Anesthesia in Patients Undergoing Off-Pump Coronary Artery Bypass Graft Surgery. Anesth Analg 2017; 125:1118-1128. [DOI: 10.1213/ane.0000000000002179] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Sabir H, Wood T, Gill H, Liu X, Dingley J, Thoresen M. Xenon depresses aEEG background voltage activity whilst maintaining cardiovascular stability in sedated healthy newborn pigs. J Neurol Sci 2016; 363:140-4. [PMID: 27000239 DOI: 10.1016/j.jns.2016.02.051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 01/25/2016] [Accepted: 02/19/2016] [Indexed: 10/22/2022]
Abstract
BACKGROUND Changes in electroencephalography (EEG) voltage range are used to monitor the depth of anaesthesia, as well as predict outcome after hypoxia-ischaemia in neonates. Xenon is being investigated as a potential neuroprotectant after hypoxic-ischaemic brain injury, but the effect of Xenon on EEG parameters in children or neonates is not known. This study aimed to examine the effect of 50% inhaled Xenon on background amplitude-integrated EEG (aEEG) activity in sedated healthy newborn pigs. METHODS Five healthy newborn pigs, receiving intravenous fentanyl sedation, were ventilated for 24 h with 50%Xenon, 30%O2 and 20%N2 at normothermia. The upper and lower voltage-range of the aEEG was continuously monitored together with cardiovascular parameters throughout a 1 h baseline period with fentanyl sedation only, followed by 24 h of Xenon administration. RESULTS The median (IQR) upper and lower aEEG voltage during 1 h baseline was 48.0 μV (46.0-50.0) and 25.0 μV (23.0-26.0), respectively. The median (IQR) aEEG upper and lower voltage ranges were significantly depressed to 21.5 μV (20.0-26.5) and 12.0 μV (12.0-16.5) from 10 min after the onset of 50% Xenon administration (p=0.002). After the initial Xenon induced depression in background aEEG voltage, no further aEEG changes were seen over the following 24h of ventilation with 50% xenon under fentanyl sedation. Mean arterial blood pressure and heart rate remained stable. CONCLUSION Mean arterial blood pressure and heart rate were not significantly influenced by 24h Xenon ventilation. 50% Xenon rapidly depresses background aEEG voltage to a steady ~50% lower level in sedated healthy newborn pigs. Therefore, care must be taken when interpreting the background voltage in neonates also receiving Xenon.
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Affiliation(s)
- Hemmen Sabir
- School of Clinical Sciences, University of Bristol, St Michael's Hospital, Bristol, United Kingdom; Departments of General Pediatrics, Neonatology and Pediatric Cardiology, University Children's Hospital, Düsseldorf, Heinrich-Heine University Düsseldorf, Germany
| | - Thomas Wood
- Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Hannah Gill
- School of Clinical Sciences, University of Bristol, St Michael's Hospital, Bristol, United Kingdom
| | - Xun Liu
- School of Clinical Sciences, University of Bristol, St Michael's Hospital, Bristol, United Kingdom
| | - John Dingley
- College of Medicine, Swansea University, United Kingdom
| | - Marianne Thoresen
- School of Clinical Sciences, University of Bristol, St Michael's Hospital, Bristol, United Kingdom; Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
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Xenon. Int Anesthesiol Clin 2015; 53:40-54. [PMID: 25807017 DOI: 10.1097/aia.0000000000000049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Impact of Hyperpolarization-activated, Cyclic Nucleotide-gated Cation Channel Type 2 for the Xenon-mediated Anesthetic Effect: Evidence from In Vitro and In Vivo Experiments. Anesthesiology 2015; 122:1047-59. [PMID: 25782754 DOI: 10.1097/aln.0000000000000635] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND The thalamus is thought to be crucially involved in the anesthetic state. Here, we investigated the effect of the inhaled anesthetic xenon on stimulus-evoked thalamocortical network activity and on excitability of thalamocortical neurons. Because hyperpolarization-activated, cyclic nucleotide-gated cation (HCN) channels are key regulators of neuronal excitability in the thalamus, the effect of xenon on HCN channels was examined. METHODS The effects of xenon on thalamocortical network activity were investigated in acutely prepared brain slices from adult wild-type and HCN2 knockout mice by means of voltage-sensitive dye imaging. The influence of xenon on single-cell excitability in brain slices was investigated using the whole-cell patch-clamp technique. Effects of xenon on HCN channels were verified in human embryonic kidney cells expressing HCN2 channels. RESULTS Xenon concentration-dependently diminished thalamocortical signal propagation. In neurons, xenon reduced HCN channel-mediated Ih current amplitude by 33.4 ± 12.2% (at -133 mV; n = 7; P = 0.041) and caused a left-shift in the voltage of half-maximum activation (V1/2) from -98.8 ± 1.6 to -108.0 ± 4.2 mV (n = 8; P = 0.035). Similar effects were seen in human embryonic kidney cells. The impairment of HCN channel function was negligible when intracellular cyclic adenosine monophosphate level was increased. Using HCN2 mice, we could demonstrate that xenon did neither attenuate in vitro thalamocortical signal propagation nor did it show sedating effects in vivo. CONCLUSIONS Here, we clearly showed that xenon impairs HCN2 channel function, and this impairment is dependent on intracellular cyclic adenosine monophosphate levels. We provide evidence that this effect reduces thalamocortical signal propagation and probably contributes to the hypnotic properties of xenon.
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Lotz C, Kehl F. Volatile Anesthetic-Induced Cardiac Protection: Molecular Mechanisms, Clinical Aspects, and Interactions With Nonvolatile Agents. J Cardiothorac Vasc Anesth 2015; 29:749-60. [DOI: 10.1053/j.jvca.2014.11.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Indexed: 02/07/2023]
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Adding 5 h delayed xenon to delayed hypothermia treatment improves long-term function in neonatal rats surviving to adulthood. Pediatr Res 2015; 77:779-83. [PMID: 25760545 DOI: 10.1038/pr.2015.49] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 11/21/2014] [Indexed: 11/08/2022]
Abstract
BACKGROUND We previously reported that combining immediate hypothermia with immediate or 2 h delayed inhalation of an inert gas, xenon, gave additive neuroprotection in rats after a hypoxic-ischemic insult, compared to hypothermia alone. Defining the therapeutic time window for this new combined intervention is crucial in clinical practice when immediate treatment is not always feasible. The aim of this study is to investigate whether combined hypothermia and xenon still provide neuroprotection in rats after a 5 h delay for both hypothermia and xenon. METHODS Seven-day-old Wistar rat pups underwent a unilateral hypoxic-ischemic insult. Pups received 5 h of treatment starting 5 h after the insult randomized between normothermia, hypothermia, or hypothermia with 50% xenon. Surviving pups were tested for fine motor function through weeks 8-10 before being euthanized at week 11. Their hemispheric and hippocampal areas were assessed. RESULTS Both delayed hypothermia-xenon and hypothermia-only treated groups had significantly less brain tissue loss than those which underwent normothermia. The functional performance after 1 wk and adulthood was significantly better after hypothermia-xenon treatment as compared to the hypothermia-only or normothermia groups. CONCLUSION Adding 50% xenon to 5 h delayed hypothermia significantly improved functional outcome as compared to delayed hypothermia alone despite similar reductions in brain area.
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LIU X, DINGLEY J, ELSTAD M, SCULL-BROWN E, STEEN PA, THORESEN M. Minimum alveolar concentration (MAC) for sevoflurane and xenon at normothermia and hypothermia in newborn pigs. Acta Anaesthesiol Scand 2013; 57:646-53. [PMID: 23316707 DOI: 10.1111/aas.12055] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2012] [Indexed: 12/21/2022]
Abstract
BACKGROUND Neuroprotection from therapeutic hypothermia increases when combined with the anaesthetic gas xenon in animal studies. A clinical feasibility study of the combined treatment has been successfully undertaken in asphyxiated human term newborns. It is unknown whether xenon alone would be sufficient for sedation during hypothermia eliminating or reducing the need for other sedative or analgesic infusions in ventilated sick infants. Minimum alveolar concentration (MAC) of xenon is unknown in any neonatal species. METHODS Eight newborn pigs were anaesthetised with sevoflurane alone and then sevoflurane plus xenon at two temperatures. Pigs were randomised to start at either 38.5°C or 33.5°C. MAC for sevoflurane was determined using the claw clamp technique at the preset body temperature. For xenon MAC determination, a background of 0.5 MAC sevoflurane was used, and 60% xenon added to the gas mixture. The relationship between sevoflurane and xenon MAC is assumed to be additive. Xenon concentrations were changed in 5% steps until a positive clamp reaction was noted. Pigs' temperature was changed to the second target, and two MAC determinations for sevoflurane and 0.5 MAC sevoflurane plus xenon were repeated. RESULTS MAC for sevoflurane was 4.1% [95% confidence interval (CI): 3.65-4.50] at 38.5°C and 3.05% (CI: 2.63-3.48) at 33.5°C, a significant reduction. MAC for xenon was 120% at 38.5°C and 116% at 33.5°C, not different. CONCLUSION In newborn swine sevoflurane, MAC was temperature dependent, while xenon MAC was independent of temperature. There was large individual variability in xenon MAC, from 60% to 120%.
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Affiliation(s)
- X. LIU
- Neonatal Neuroscience; School of Clinical Sciences; University of Bristol; Bristol; UK
| | - J. DINGLEY
- Anesthetics; Swansea Medical School; University of Swansea; Swansea; UK
| | - M. ELSTAD
- Department of Physiology; Institute of Basic Medical Sciences; University of Oslo; Oslo; Norway
| | - E. SCULL-BROWN
- Neonatal Neuroscience; School of Clinical Sciences; University of Bristol; Bristol; UK
| | - P. A. STEEN
- Clinic for Emergencies and Critical Care; University of Oslo and Oslo University Hospital; Norway
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Booker RD, Sum AK. Biophysical changes induced by xenon on phospholipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1347-56. [PMID: 23376329 DOI: 10.1016/j.bbamem.2013.01.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 12/28/2012] [Accepted: 01/22/2013] [Indexed: 12/20/2022]
Abstract
Structural and dynamic changes in cell membrane properties induced by xenon, a volatile anesthetic molecule, may affect the function of membrane-mediated proteins, providing a hypothesis for the mechanism of general anesthetic action. Here, we use molecular dynamics simulation and differential scanning calorimetry to examine the biophysical and thermodynamic effects of xenon on model lipid membranes. Our results indicate that xenon atoms preferentially localize in the hydrophobic core of the lipid bilayer, inducing substantial increases in the area per lipid and bilayer thickness. Xenon depresses the membrane gel-liquid crystalline phase transition temperature, increasing membrane fluidity and lipid head group spacing, while inducing net local ordering effects in a small region of the lipid carbon tails and modulating the bilayer lateral pressure profile. Our results are consistent with a role for nonspecific, lipid bilayer-mediated mechanisms in producing xenon's general anesthetic action.
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Affiliation(s)
- Ryan D Booker
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO 80401, USA
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20
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White JPM, Calcott G, Jenes A, Hossein M, Paule CC, Santha P, Davis JB, Ma D, Rice ASC, Nagy I. Xenon reduces activation of transient receptor potential vanilloid type 1 (TRPV1) in rat dorsal root ganglion cells and in human TRPV1-expressing HEK293 cells. Life Sci 2011; 88:141-9. [PMID: 21056583 DOI: 10.1016/j.lfs.2010.11.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 09/20/2010] [Accepted: 10/27/2010] [Indexed: 11/19/2022]
Abstract
AIMS Xenon provides effective analgesia in several pain states at sub-anaesthetic doses. Our aim was to examine whether xenon may mediate its analgesic effect, in part, through reducing the activity of transient receptor potential vanilloid type 1 (TRPV1), a receptor known to be involved in certain inflammatory pain conditions. MAIN METHODS We studied the effect of xenon on capsaicin-evoked cobalt uptake in rat cultured primary sensory neurons and in human TRPV1 (hTRPV1)-expressing human embryonic kidney 293 (HEK293) cells. We also examined xenon's effect on the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) in the rat spinal dorsal horn evoked by hind-paw injection of capsaicin. KEY FINDINGS Xenon (75%) reduced the number of primary sensory neurons responding to the TRPV1 agonist, capsaicin (100 nM-1 μM) by ~25% to ~50%. Xenon reduced the number of heterologously-expressed hTRPV1 activated by 300 nM capsaicin by ~50%. Xenon (80%) reduced by ~40% the number of phosphorylated ERK1/2-expressing neurons in rat spinal dorsal horn resulting from hind-paw capsaicin injection. SIGNIFICANCE Xenon substantially reduces the activity of TRPV1 in response to noxious stimulation by the specific TRPV1 agonist, capsaicin, suggesting a possible role for xenon as an adjunct analgesic where hTRPV1 is an active contributor to the excitation of primary afferents which initiates the pain sensation.
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Affiliation(s)
- John P M White
- Anaesthetics, Pain Medicine and Intensive Care Section, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, Chelsea and Westminster Hospital, 369, Fulham Road, London, SW10 9NH, United Kingdom
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Delhaye O, Robin E, Bazin JE, Ripart J, Lebuffe G, Vallet B. [Benefits and indications of xenon anaesthesia]. ANNALES FRANCAISES D'ANESTHESIE ET DE REANIMATION 2010; 29:635-641. [PMID: 20667685 DOI: 10.1016/j.annfar.2010.04.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2009] [Accepted: 04/16/2010] [Indexed: 05/29/2023]
Abstract
OBJECTIVE To analyze the current knowledge related to xenon anaesthesia. DATA SOURCES References were obtained from computerized bibliographic research (Medline), recent review articles, the library of the service and personal files. STUDY SELECTION All categories of articles on this topic have been selected. DATA EXTRACTION Articles have been analyzed for biophysics, pharmacology, toxicity and environmental effects, clinical effects and using prospect. DATA SYNTHESIS The noble gas xenon has anaesthetic properties that have been recognized 50 years ago. Xenon is receiving renewed interest because it has many characteristics of an ideal anaesthetic. In addition to its lack of effects on cardiovascular system, xenon has a low solubility enabling faster induction of and emergence from anaesthesia than with other inhalational agents. Nevertheless, at present, the cost and rarity of xenon limits widespread use in clinical practice. The development of closed rebreathing system that allowed recycling of xenon and therefore reducing its waste has led to a recent interest in this gas. CONCLUSION Reducing its cost will help xenon to find its place among anaesthetic agents and extend its use to severe patients with specific pathologies.
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Affiliation(s)
- O Delhaye
- Fédération d'anesthésie-réanimation, CHRU de Lille, rue Polonovski, Lille cedex, France
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Dickinson R, Franks NP. Bench-to-bedside review: Molecular pharmacology and clinical use of inert gases in anesthesia and neuroprotection. Crit Care 2010; 14:229. [PMID: 20836899 PMCID: PMC2945072 DOI: 10.1186/cc9051] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In the past decade there has been a resurgence of interest in the clinical use of inert gases. In the present paper we review the use of inert gases as anesthetics and neuroprotectants, with particular attention to the clinical use of xenon. We discuss recent advances in understanding the molecular pharmacology of xenon and we highlight specific pharmacological targets that may mediate its actions as an anesthetic and neuroprotectant. We summarize recent in vitro and in vivo studies on the actions of helium and the other inert gases, and discuss their potential to be used as neuroprotective agents.
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Affiliation(s)
- Robert Dickinson
- Biophysics Section, Blackett Laboratory, Imperial College London, South Kensington, London SW7 2AZ, UK.
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Höcker J, Raitschew B, Meybohm P, Broch O, Stapelfeldt C, Gruenewald M, Cavus E, Steinfath M, Bein B. Differences between bispectral index and spectral entropy during xenon anaesthesia: a comparison with propofol anaesthesia. Anaesthesia 2010; 65:595-600. [DOI: 10.1111/j.1365-2044.2010.06344.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Weng Y, Yang L, Corringer PJ, Sonner JM. Anesthetic sensitivity of the Gloeobacter violaceus proton-gated ion channel. Anesth Analg 2009; 110:59-63. [PMID: 19933531 DOI: 10.1213/ane.0b013e3181c4bc69] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A prokaryotic member of the gamma-aminobutyric acid type A receptor superfamily (GLIC) was recently cloned from the cyanobacterium Gloeobacter violaceus, its function characterized, and its 3-dimensional x-ray diffraction crystal structure determined. We report its modulation by 9 anesthetics using 2-electrode voltage clamping in Xenopus laevis oocytes. Desflurane, halothane, isoflurane, sevoflurane, and propofol inhibited currents through GLIC at and below concentrations used clinically. Hill numbers averaged 0.3, indicating negative cooperativity or multiple sites or mechanisms of action. A 2-site model fit the data for desflurane and halothane better than a 1-site model. Xenon and etomidate modulated GLIC at or above clinical concentrations, with no cooperativity. Ethanol and nitrous oxide did not modulate GLIC at surgical anesthetic concentrations. These investigations lay the groundwork for further structural and functional studies of anesthetic actions on GLIC.
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Affiliation(s)
- Yun Weng
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, CA 94143-0464, USA
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25
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Eger EI, Tang M, Liao M, Laster MJ, Solt K, Flood P, Jenkins A, Raines D, Hendrickx JF, Shafer SL, Yasumasa T, Sonner JM. Inhaled anesthetics do not combine to produce synergistic effects regarding minimum alveolar anesthetic concentration in rats. Anesth Analg 2008; 107:479-85. [PMID: 18633026 DOI: 10.1213/01.ane.0000295805.70887.65] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND We hypothesized that pairs of inhaled anesthetics having divergent potencies [one acting weakly at minimum alveolar anesthetic concentration (MAC); one acting strongly at MAC] on specific receptors/channels might act synergistically, and that such deviations from additivity would support the notion that anesthetics act on multiple sites to produce anesthesia. METHODS Accordingly, we studied the additivity of MAC for 11 anesthetic pairs divergently (one weakly, one strongly) affecting a specific receptor/channel at MAC. By "divergently," we usually meant that at MAC the more strongly acting anesthetic enhanced or blocked the in vitro receptor or channel at least twice (and usually more) as much as did the weakly acting anesthetic. The receptors/channels included: TREK-1 and TASK-3 potassium channels; and gamma-aminobutyric acid type A, glycine, N-methyl-D-aspartic acid, and acetylcholine receptors. We also studied the additivity of cyclopropane-benzene because the N-methyl-D-aspartic acid blocker MK-801 had divergent effects on the MACs of these anesthetics. We also studied four pairs that included nitrous oxide because nitrous oxide had been reported to produce infraadditivity (antagonism) when combined with isoflurane. RESULTS All combinations produced a result within 10% of that which would be predicted by additivity except for the combination of isoflurane with nitrous oxide where infraadditivity was found. CONCLUSIONS Such results are consistent with the notion that inhaled anesthetics act on a single site to produce immobility in the face of noxious stimulation.
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Affiliation(s)
- Edmond I Eger
- Department of Anesthesia, S-455, University of California, San Francisco, CA 94143-0464, USA.
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Shafer SL, Hendrickx JFA, Flood P, Sonner J, Eger EI. Additivity Versus Synergy: A Theoretical Analysis of Implications for Anesthetic Mechanisms. Anesth Analg 2008; 107:507-24. [PMID: 18633029 DOI: 10.1213/ane.0b013e31817b7140] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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27
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Hendrickx JFA, Eger EI, Sonner JM, Shafer SL. Is Synergy the Rule? A Review of Anesthetic Interactions Producing Hypnosis and Immobility. Anesth Analg 2008; 107:494-506. [PMID: 18633028 DOI: 10.1213/ane.0b013e31817b859e] [Citation(s) in RCA: 185] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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28
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Schmidt M, Marx T, Kotzerke J, Lüderwald S, Armbruster S, Topalidis P, Schirmer U, Reinelt H. Cerebral and regional organ perfusion in pigs during xenon anaesthesia. Anaesthesia 2008. [DOI: 10.1111/j.1365-2044.2001.02322.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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ABRAINI JACQUESH, DAVID HÉLÈNEN, LEMAIRE MARC. Potentially Neuroprotective and Therapeutic Properties of Nitrous Oxide and Xenon. Ann N Y Acad Sci 2008. [DOI: 10.1111/j.1749-6632.2005.tb00036.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Dingley J, Hobbs C, Ferguson J, Stone J, Thoresen M. Xenon/hypothermia neuroprotection regimes in spontaneously breathing neonatal rats after hypoxic-ischemic insult: the respiratory and sedative effects. Anesth Analg 2008; 106:916-23, table of contents. [PMID: 18292440 DOI: 10.1213/ane.0b013e3181618669] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Hypothermia (HT) reduces neuronal injury after perinatal asphyxia. The anesthetic gas xenon (XE) may enhance this effect. We investigated the sedative and respiratory effects of variable XE concentrations at 37 degrees C normothermia (NT) or 32 degrees C HT after a hypoxic-ischemic (HI) insult to determine the concentration at which XE was a respiratory depressant in spontaneously breathing 7-day-old rat pups. METHODS (I) In three control groups, the effects of fasting at NT and HT were investigated. (II) Six groups were subjected to a HI insult (left carotid ligation then 90 min breathing 8% oxygen); three then breathed Air, 50%Xe or 70%Xe for 5 h at NT (NT(Air), NT(50%Xe), NT(70%Xe)), while three breathed identical mixtures during HT (HT(Air), HT(50%Xe), or HT(70%Xe)), in addition to a control group. Blood gases, glucose, and lactate were measured. Sedation (spontaneous movement/respiratory rate) was recorded. RESULTS Blood chemistry data were successfully obtained from 70 pups. (I) Pups maintained normal blood gas, glucose, and lactate values after 9 h fasting at NT or HT. (II) After HI insult, in comparison with control and NT(Air) groups, 70%Xe at both NT and HT produced higher PCO2 and lower pH values while the HT(Air) and HT(50%Xe) groups only had lower pH values. The HT(70%Xe) combination produced the highest PCO2 and lowest pH values (56.8 mm Hg, 7.35, respectively) and the greatest sedative effect. CONCLUSION After HI insult, 70%Xe at both NT and HT induced sedation, respiratory depression, CO2 retention, and a decrease in pH relative to air and control groups. The effects were largely avoided with 50%Xe.
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Affiliation(s)
- John Dingley
- Clinical Science at South Bristol, Child Health, University of Bristol, St. Michael's Hospital, Bristol, UK.
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31
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Barakat AR, Schreiber MN, Flaschar J, Georgieff M, Schraag S. The Effective Concentration 50 (EC50) for Propofol with 70% Xenon Versus 70% Nitrous Oxide. Anesth Analg 2008; 106:823-9, table of contents. [DOI: 10.1213/ane.0b013e318161534b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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32
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David HN, Haelewyn B, Rouillon C, Lecoq M, Chazalviel L, Apiou G, Risso JJ, Lemaire M, Abraini JH. Neuroprotective effects of xenon: a therapeutic window of opportunity in rats subjected to transient cerebral ischemia. FASEB J 2007; 22:1275-86. [PMID: 18024836 DOI: 10.1096/fj.07-9420com] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Brain insults are a major cause of acute mortality and chronic morbidity. Given the largely ineffective current therapeutic strategies, the development of new and efficient therapeutic interventions is clearly needed. A series of previous investigations has shown that the noble and anesthetic gas xenon, which has low-affinity antagonistic properties at the N-methyl-D-aspartate (NMDA) receptor, also exhibits potentially neuroprotective properties with no proven adverse side effects. Surprisingly and in contrast with most drugs that are being developed as therapeutic agents, the dose-response neuroprotective effect of xenon has been poorly studied, although this effect could be of major critical importance for its clinical development as a neuroprotectant. Here we show, using ex vivo and in vivo models of excitotoxic insults and transient brain ischemia, that xenon, administered at subanesthetic doses, offers global neuroprotection from reduction of neurotransmitter release induced by ischemia, a critical event known to be involved in excitotoxicity, to reduction of subsequent cell injury and neuronal death. Maximal neuroprotection was obtained with xenon at 50 vol%, a concentration at which xenon further exhibited significant neuroprotective effects in vivo even when administered up to 4 h after intrastriatal NMDA injection and up to at least 2 h after induction of transient brain ischemia.
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Chon D, Beck KC, Simon BA, Shikata H, Saba OI, Hoffman EA. Effect of low-xenon and krypton supplementation on signal/noise of regional CT-based ventilation measurements. J Appl Physiol (1985) 2007; 102:1535-44. [PMID: 17122371 DOI: 10.1152/japplphysiol.01235.2005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Xenon computed tomography (Xe-CT) is used to estimate regional ventilation by measuring regional attenuation changes over multiple breaths while rebreathing a constant Xe concentration ([Xe]). Xe-CT has potential human applications, although anesthetic properties limit [Xe] to ≤35%. We investigate effects of lower [Xe], including a low [Xe]-krypton (Kr) combination, on time constant (TC) determination. Six anesthetized sheep were scanned prone and supine using multidetector row CT. Lungs were imaged by respiratory gating during washin of a 30%, 40%, 55% Xe, and a 30% Xe/30% Kr mixture. Using Kr avoids unwanted effects of Xe. Mean TCs, coefficients of variation (CV), and half confidence intervals (CI)/mean served as indexes of sensitivity to noise. Mean supine and prone TCs of three [Xe] values were not significantly different. Average CVs of TCs increased from 57% (55% Xe), 58% (40% Xe), and 73% (30% Xe) ( P < 0.05: paired t-tests; 30% Xe vs. higher [Xe]). Monte Carlo simulation indicated a CV based on inherent image noise was 8% for 55% Xe and 17% for 30% Xe ( P < 0.05). Adding 30% Kr to 30% Xe gave a washin signal equivalent to 40% Xe. Half CI/mean using the 30% Xe/30% Kr mixture was not significantly different from 55 and 40% Xe. Although average TCs were not affected by changes in [Xe], the higher CV and half CI/mean suggested reduced signal-to-noise ratio at the 30% [Xe]. The 30% Xe/30% Kr mixture was comparable to that of 40% Xe, providing an important agent for CT-based assessment of regional ventilation in humans.
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Affiliation(s)
- Deokiee Chon
- Department of Radiology, University of Iowa, Iowa City, Iowa 52242, USA
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Solt K, Eger EI, Raines DE. Differential Modulation of Human N-Methyl-d-Aspartate Receptors by Structurally Diverse General Anesthetics. Anesth Analg 2006; 102:1407-11. [PMID: 16632818 DOI: 10.1213/01.ane.0000204252.07406.9f] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
N-Methyl-d-aspartate (NMDA) receptors have a presumed role in excitatory synaptic transmission and nociceptive pathways. Although previous studies have found that inhaled anesthetics inhibit NMDA receptor-mediated currents at clinically relevant concentrations, the use of different experimental protocols, receptor subtypes, and/or tissue sources confounds quantitative comparisons of the NMDA receptor inhibitory potencies of inhaled anesthetics. In the present study, we sought to fill this void by defining, using the two-electrode voltage-clamp technique, the extent to which diverse clinical and aromatic inhaled anesthetics inhibit the NR1/NR2B subtype of the human NMDA receptor expressed in Xenopus laevis oocytes. At 1 minimum alveolar anesthetic concentration (MAC), anesthetic compounds reversibly inhibited NMDA receptor currents by 12 +/- 6% to 74 +/- 6%. These results demonstrate that equianesthetic concentrations of inhaled anesthetics can differ considerably in the extent to which they inhibit NMDA receptors. Such differences may be useful for defining the role that this receptor plays in producing the in vivo actions of general anesthetics.
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Affiliation(s)
- Ken Solt
- Department of Anesthesia and Critical Care, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
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King R, Bretland M, Wilkes A, Dingley J. Xenon measurement in breathing systems: a comparison of ultrasonic and thermal conductivity methods. Anaesthesia 2005; 60:1226-30. [PMID: 16288621 DOI: 10.1111/j.1365-2044.2005.04379.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Xenon is an anaesthetic and possibly neuroprotective gas that is impossible to measure using conventional anaesthetic gas analysers. We compared the performance of two commissioned xenon analysers using ultrasonic and thermal conductivity principles against a reference method of laser refractometry. An experimental gas circuit was constructed and xenon concentrations compared over a range of 0-100% in oxygen. Eighty-two paired measurements were made comparing the experimental methods with laser refractometry. The ultrasonic method displayed good agreement with laser refractometry, with a mean difference of - 0.74% and two standard deviation limits of agreement of + 1.08% to - 2.56%. The agreement between laser refractometry and thermal conductivity was poor, the mean difference being - 5.37%, with two standard deviation limits of agreement of + 0.6% to - 11.3%. The ultrasonic method for measuring xenon concentrations can be used in breathing circuits. The thermal conductivity instrument may need further development.
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Affiliation(s)
- R King
- Department of Anaesthetics, Morriston Hospital, Swansea SA6 6NL, UK
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Hanne P, Goto T, Nakata Y, Ishiguro Y, Morita S. Nitrogen accumulation during closed circuit anesthesia depends on the type of surgery. J Clin Anesth 2005; 17:504-8. [PMID: 16297749 DOI: 10.1016/j.jclinane.2004.12.016] [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: 05/17/2004] [Accepted: 12/01/2004] [Indexed: 11/23/2022]
Abstract
STUDY OBJECTIVE The aim of this study is to test the hypothesis that the amount of nitrogen that accumulates within the closed breathing system would be greater during open abdominal surgery than during superficial surgery with small wounds. DESIGN Prospective, comparative study. SETTING Operating rooms of a university hospital. PATIENTS Fourteen American Society of Anesthesiologists physical status I and II adult patients scheduled for abdominal surgery (n = 7) or tympanoplasty (n = 7). INTERVENTIONS After induction of anesthesia and endotracheal intubation, the patients were denitrogenated for 30 minutes using 100% oxygen at a fresh gas flow of 10 L/min. The breathing system was then closed and patients were anesthetized using 60% xenon in oxygen, supplemented with epidural anesthesia in the abdominal surgery group and sevoflurane in the tympanoplasty group. MEASUREMENTS Nitrogen concentration in the breathing system was determined by gas chromatography immediately before and 2 hours after the breathing system was closed. MAIN RESULTS The median (range) increase in nitrogen concentration during the 2-hour period of closed circuit anesthesia was greater in the abdominal surgery patients than in the tympanoplasty patients (6.5% [4.0%-10.2%] vs 2.5% [1.4%-8.4%], P = 0.035, Mann-Whitney U test). CONCLUSIONS The amount of nitrogen accumulation during closed circuit anesthesia is greater during open abdominal surgery than in superficial surgery such as tympanoplasty. We postulate that during open abdominal surgery, nitrogen in the ambient air enters the body across the peritoneum and then diffuses into the alveoli to be exhaled.
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Affiliation(s)
- Pia Hanne
- Department of Anesthesiology and Surgical Intensive Care Medicine, University Hospital Schleswig-Holstein, Campus Kiel, Schwanenweg 21, D-24105 Kiel, Germany
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Simon BA. Regional ventilation and lung mechanics using X-Ray CT. Acad Radiol 2005; 12:1414-22. [PMID: 16253853 DOI: 10.1016/j.acra.2005.07.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Revised: 07/25/2005] [Accepted: 07/27/2005] [Indexed: 11/21/2022]
Abstract
Advances in computed tomographic (CT) imaging of the lung in the past decade, particularly with increased speed, resolution, gating capability, and rapidly expanding volumetric image acquisition, along with advances in image processing, have expanded the repertoire of imaging methods beyond anatomic visualization into the noninvasive study of regional lung physiological function. Recognizing that significant local disease or dysfunction can exist before global measures begin to deteriorate, the motivation for the development and application of these regional techniques is to further our understanding of the basic pathophysiological characteristics of evolving lung disease and, ultimately, develop sensitive measures for its early detection. This review emphasizes the key elements of ventilation and lung mechanics relevant for regional approaches and CT measurement principles available for their study. Examples of established and evolving methods for imaging regional ventilation and mechanics, including the xenon CT ventilation method; the relationship between changing regional CT density and air volume change; and registration-based methods for examining regional lung expansion and strain, are presented.
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Affiliation(s)
- Brett A Simon
- Department of Anesthesiology, Johns Hopkins Hospital, Baltimore, MD 21287-8711, USA.
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Abstract
Of all the inert gases, only xenon has considerable anaesthetic properties under normobaric conditions. Its very low blood/gas partition coefficient makes induction of and emergence from anaesthesia more rapid compared with other inhalational anaesthetics. In experimental and clinical studies the safety and efficiency of xenon as an anaesthetic has been demonstrated. Xenon causes several physiological changes, which mediate protection of the brain or myocardium. The use of xenon might therefore be beneficial in certain clinical situations, as in patients at high risk for neurological or cardiac damage.
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Affiliation(s)
- Benedikt Preckel
- Department of Anaesthesiology, Dusseldorf University Hospital, P.O. Box 10 10 07, D-40001 Düsseldorf, Germany.
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39
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Abstract
PURPOSE OF REVIEW Xenon anaesthesia has recently been evaluated in large-scale clinical trials that have demonstrated xenon's safe and effective clinical profile. Despite the relatively high cost of xenon anaesthesia, xenon has clear clinical advantages over other current anaesthetics. RECENT FINDINGS Xenon possesses distinct neuroprotective and cardioprotective properties in addition to a favourable pharmacokinetic profile and analgesic effects. In addition, xenon exerts preconditioning effects in the heart and may offer postoperative, as well as intraoperative, cardio and neuroprotection. SUMMARY Further clinical trials are required to evaluate the role that xenon can play in the perioperative period.
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Affiliation(s)
- Robert D Sanders
- Department of Anaesthetics and Intensive Care, Faculty of Medicine, Imperial College, London, UK
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Casey ND, Chandler J, Gifford D, Falter F. Microbubble production in an in vitro cardiopulmonary bypass circuit ventilated with xenon. Perfusion 2005; 20:145-50. [PMID: 16038386 DOI: 10.1191/0267659105pf799oa] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Xenon, as an anaesthetic gas, has the potential to be used in an increasing range of applications. However, its use in cardiopulmonary bypass (CPB) has not yet progressed from the rat model due to concerns that its relative insolubility may cause microbubble formation and/or expansion in the micro-vasculature of the patient. An in vitro CPB circuit was designed to create and measure gaseous microbubbles over a range of temperature gradients, pressure drop and gas tensions. We were able to demonstrate that our test circuit did not produce any significant microbubbles and that, under normal physiological blood pressures, a fixed gas bubble in connection with the circuit did not grow in the presence of Xe.
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Schmidt M, Marx T, Armbruster S, Reinelt H, Schirmer U. Effect of Xenon on elevated intracranial pressure as compared with nitrous oxide and total intravenous anesthesia in pigs. Acta Anaesthesiol Scand 2005; 49:494-501. [PMID: 15777297 DOI: 10.1111/j.1399-6576.2005.00609.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Xenon in low concentrations has been investigated in neuroradiology to measure cerebral blood flow (CBF). Several reports have suggested that inhalation of Xenon might increase intracranial pressure (ICP) by increasing the cerebral blood flow and blood volume, raising concerns about using Xenon as an anesthetic in higher concentrations for head-injured patients. A porcine study is presented in which the effects of inhaled 75% Xenon on elevated ICP, cerebral perfusion pressure and the efficacy of hyperventilation for ICP treatment were compared with nitrous oxide anesthesia and total intravenous anesthesia (TIVA). METHODS Twenty-one pentobarbital-anesthetized pigs (age: 12-16 weeks) were randomly assigned to three groups to receive either 4 h of Xenon-oxygen ventilation, nitrous oxide-oxygen ventilation or air-oxygen (75%/25%) ventilation, respectively. After instrumentation for parenchymal ICP measurement and ICP manipulation, an epidurally placed 6-F balloon catheter was inflated until a target ICP of 20 mmHg was achieved. After 4 h of anesthesia hyper- and hypoventilation maneuvers were performed and consecutive ICP and CBF changes were investigated. RESULTS Intracranial pressure and CBF increased significantly in the nitrous oxide group as compared with the controls. There was no increase of ICP or CBF in the Xenon or control group. Intracranial pressure changed in all three groups corresponding to hyper- and hypoventilation. CONCLUSIONS During Xenon anesthesia, elevated ICP is not increased further and is partially reversible by hyperventilation. Our study suggests that inhalation of 75% Xenon seems not to be contraindicated in patients with elevated ICP.
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Affiliation(s)
- M Schmidt
- Department Cardiac Anesthesia, University of Ulm, Ulm, Germany.
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White IL, Franks NP, Dickinson R. Effects of isoflurane and xenon on Ba2+-currents mediated by N-type calcium channels. Br J Anaesth 2005; 94:784-90. [PMID: 15778267 DOI: 10.1093/bja/aei126] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Isoflurane and xenon are inhalation general anaesthetics with differing clinical profiles and contrasting synaptic actions. Both agents have been shown to depress excitatory synaptic responses. Whether this is via pre-synaptic or post-synaptic mechanisms has not been determined clearly. N-type calcium channels are a putative pre-synaptic target for these agents. We tested whether N-type calcium channels were sensitive to isoflurane and xenon and whether there was any stereoselectivity in the effect of isoflurane. METHODS We used patch-clamp electrophysiology on isolated HEK293 cells stably expressing N-type calcium channels to investigate the effects of isoflurane and xenon on barium currents mediated by N-type calcium channels. RESULTS Racemic isoflurane caused a concentration-dependent reduction (11-35%) in the peak current through the N-type channels in the concentration range 0.15-1.22 mM. In the clinically relevant concentration range the inhibition was small. At an isoflurane concentration of 0.31 mM (equivalent to 1 MAC), the peak N-type current was inhibited by 14 (1)%. The optical isomers of isoflurane were found to be equally potent at inhibiting currents through N-type channels. The inert gas anaesthetic xenon was found to have no measureable effect on N-type channels at a concentration of 3.4 mM (approximately 1 MAC). CONCLUSIONS These results suggest that N-type calcium channels are not the targets mediating general anaesthesia with these two inhalation agents.
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Affiliation(s)
- I L White
- Department of Anaesthetics and Intensive Care, Faculty of Medicine, Imperial College London, Chelsea and Westminster Campus, 369 Fulham Road, London SW10 9NH, UK
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Luginbühl M, Petersen-Felix S, Zbinden AM, Schnider TW. Xenon does not reduce opioid requirement for orthopedic surgery. Can J Anaesth 2005; 52:38-44. [PMID: 15625254 DOI: 10.1007/bf03018578] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
PURPOSE Is to test the hypothesis that 70% xenon has a relevant opioid sparing effect compared to a minimum alveolar concentration (MAC)-equivalent combination of N(2)O and desflurane. METHODS In this randomized, controlled study of 30 patients undergoing major orthopedic surgery, we determined the plasma alfentanil concentration required to suppress response to skin incision in 50% of patients (Cp(50)) anesthetized with xenon (70%) or a combination of N(2)O (70%) and desflurane (2%). A response was defined as movement, pressor response > 15 mmHg, heart rate > 90 beats x min(-1), autonomic reactions or a combination of these. At skin incision, alfentanil was administered at a randomly selected target plasma concentration thereafter the concentration was increased or decreased according to the patient's response. After skin incision, desflurane was adjusted to maintain the bispectral index below 60 and prevent responsiveness in both groups. RESULTS The Cp(50) (+/- standard error) of alfentanil was 83 +/- 48ng x mL(-1) with xenon and 49 +/- 26 ng x mL(-1) with N(2)O/desflurane (P =0.451). During surgery five xenon and 15 N(2)O/desflurane patients were given desflurane at 1.0 +/- 0.5 volume % and 2.5 +/- 0.7 volume %. The total age adjusted MAC was 0.97 +/- 0.07 and 0.94 +/- 0.07 respectively (P = 0.217). The intraoperative plasma alfentanil concentrations were 95 +/- 80 and 93 +/- 60 ng x mL(-1) respectively (mean +/- SD; P = 0.451). Patients given xenon were slightly more bradycardic, whereas blood pressure was similar. CONCLUSION Xenon compared to a MAC-equivalent combination of N(2)O and desflurane does not substantially reduce opioid requirement for orthopedic surgery. A small but clinically irrelevant difference cannot be excluded, however.
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Affiliation(s)
- Martin Luginbühl
- Department of Anesthesiology, University Hospital, CH-3010 Bern, Switzerland.
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Goto T, Hanne P, Ishiguro Y, Ichinose F, Niimi Y, Morita S. Cardiovascular effects of xenon and nitrous oxide in patients during fentanyl-midazolam anaesthesia*. Anaesthesia 2004; 59:1178-83. [PMID: 15549976 DOI: 10.1111/j.1365-2044.2004.03900.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Xenon anaesthesia appears to have minimal haemodynamic effects. The purpose of this randomised prospective study was to compare the cardiovascular effects of xenon and nitrous oxide in patients with known ischaemic heart disease. In 20 patients who were due to undergo coronary artery bypass graft surgery, 30 min following induction of anaesthesia with fentanyl 30 microg x kg(-1) and midazolam 0.1 mg x kg(-1) but prior to the start of surgery, xenon or nitrous oxide 60% was administered for 15 min. The results showed that xenon caused a minimal decrease in the mean arterial pressure (from 81 (7) to 75 (8) mmHg, mean (SD)), but did not affect the systolic function of the left ventricle, as demonstrated by unchanged left ventricular stroke work index (LVSWI) and the fractional area change of the left ventricle (FAC) derived from transoesophageal echocardiography (TOE). However, in contrast, nitrous oxide was found to decrease the mean arterial pressure (from 81 (8) to 69 (7) mmHg), the LVSWI, and the FAC. The cardiac index, central venous and pulmonary artery occlusion pressures, systemic and pulmonary vascular resistances, and the TOE-derived E/A ratio through the mitral valve were unchanged by xenon or nitrous oxide. We conclude that xenon provides improved haemodynamic stability compared with nitrous oxide, conserving the left ventricular systolic function.
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Affiliation(s)
- T Goto
- Teikyo University, Ichihara Hospital, 3426-3 Anesaki, Ichihara-shi, Chiba-ken, 299-0111, Japan.
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Abstract
Hyperpolarized gases have found a steadily increasing range of applications in nuclear magnetic resonance (NMR) and NMR imaging (MRI). They can be regarded as a new class of MR contrast agent or as a way of greatly enhancing the temporal resolution of the measurement of processes relevant to areas as diverse as materials science and biomedicine. We concentrate on the properties and applications of hyperpolarized xenon. This review discusses the physics of producing hyperpolarization, the NMR-relevant properties of 129Xe, specific MRI methods for hyperpolarized gases, applications of xenon to biology and medicine, polarization transfer to other nuclear species and low-field imaging.
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Affiliation(s)
- Ana-Maria Oros
- Institute of Medicine, Research Centre Jiilich, 52425 Jülich, Germany.
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Hüneke R, Fassl J, Rossaint R, Lückhoff A. Effects of volatile anesthetics on cardiac ion channels. Acta Anaesthesiol Scand 2004; 48:547-61. [PMID: 15101848 DOI: 10.1111/j.0001-5172.2004.00391.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The focus of the present review is on how interference with various ion channels in the heart may be the molecular basis for cardiac side-effects of gaseous anesthetics. Electrophysiological studies in isolated animal and human cardiomyocytes have identified the L-type Ca(2+) channel as a prominent target of anesthetics. Since this ion channel is of fundamental importance for the plateau phase of the cardiac action potential as well as for Ca(2+)-mediated electromechanical coupling, its inhibition may facilitate arrhythmias by shortening the refractory period and may decrease the contractile force. Effective inhibition of this ion channel has been shown for clinically used concentrations of halothane and, to a lesser extent, of isoflurane and sevoflurane, whereas xenon was without effect. Anesthetics furthermore inhibit several types of voltage-gated K(+) channels. Thereby, they may disturb the repolarization and bear a considerable risk for the induction of ventricular tachycardia in predisposed patients. In future, an advanced understanding of cardiac side-effects of anesthetics will derive from more detailed analyses of how and which channels are affected as well as from a better comprehension of how altered channel function influences heart function.
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Affiliation(s)
- R Hüneke
- Department of Anesthesiology, University Hospital, Rheinisch-Westfalische-Technische Hochschule (RWTH), Aachen, Germany
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Gruss M, Bushell TJ, Bright DP, Lieb WR, Mathie A, Franks NP. Two-pore-domain K+ channels are a novel target for the anesthetic gases xenon, nitrous oxide, and cyclopropane. Mol Pharmacol 2004; 65:443-52. [PMID: 14742687 DOI: 10.1124/mol.65.2.443] [Citation(s) in RCA: 227] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Nitrous oxide, xenon, and cyclopropane are anesthetic gases that have a distinct pharmacological profile. Whereas the molecular basis for their anesthetic actions remains unclear, they behave very differently to most other general anesthetics in that they have little or no effect on GABAA receptors, yet strongly inhibit the N-methyl-d-aspartate subtype of glutamate receptors. Here we show that certain members of the two-pore-domain K+ channel superfamily may represent an important new target for these gaseous anesthetics. TREK-1 is markedly activated by clinically relevant concentrations of nitrous oxide, xenon, and cyclopropane. In contrast, TASK-3, a member of this family that is very sensitive to volatile anesthetics, such as halothane, is insensitive to the anesthetic gases. We demonstrate that the C-terminal cytoplasmic domain is not an absolute requirement for the actions of the gases, although it clearly plays an important modulatory role. Finally, we show that Glu306, an amino acid that has previously been found to be important in the modulation of TREK-1 by arachidonic acid, membrane stretch and internal pH, is critical for the activating effects of the anesthetic gases.
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Affiliation(s)
- Marco Gruss
- Biophysics Section, Department of Biological Sciences, The Blackett Laboratory, Imperial College London, London, United Kingdom
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Hecker KE, Horn N, Baumert JH, Reyle-Hahn SM, Heussen N, Rossaint R. Minimum alveolar concentration (MAC) of xenon in intubated swine. Br J Anaesth 2004; 92:421-4. [PMID: 14742330 DOI: 10.1093/bja/aeh077] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The minimum alveolar concentration (MAC) is a traditional index of the hypnotic potency of an inhalational anaesthetic. To investigate the anaesthetic as well as the unwanted effects of xenon (Xe) in a swine model, it is useful to know MAC(Xe). METHODS The study was performed using ten swine (weight 27.8-35.4 kg) anaesthetized with halothane and Xe 0, 15, 30, 40, 50 and 65% in oxygen. With each Xe concentration, various concentrations of halothane were administered in a step-by-step design. For each combination, a supramaximal pain stimulus (claw clamp) was applied and the appearance of a withdrawal reaction was recorded. The MAC(Xe) with halothane was calculated using a logistic regression model. RESULTS During stable ventilation, haemodynamics and temperature, MAC(Xe) value was determined as 119 vol. % (95% confidence limits 103-135). CONCLUSION MAC(Xe) in swine was calculated by extrapolation of a logistic regression model. Its theoretical value is 119 vol. %.
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Affiliation(s)
- K E Hecker
- Department of Anaesthesiology, Klinikum der RWTH Aachen, Pauwelsstr. 30, D-52074 Aachen, Germany.
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Abstract
The 'noble' gases have been known to have anaesthetic properties for 50 years yet only recently has their application become a clinical reality. In this review we describe the preclinical and clinical studies that have led to a resurgence of interest in the use of the element xenon as an anaesthetic. Furthermore, we highlight specific areas where xenon demonstrates advantages over other anaesthetics, including safety, beneficial pharmacokinetics, cardiovascular stability, analgesia and neuroprotection.
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Affiliation(s)
- Robert D Sanders
- Department of Anaesthetics and Intensive Care, Faculty of Medicine, Imperial College London, UK
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50
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Hecker KE, Baumert JH, Horn N, Reyle-Hahn M, Heussen N, Rossaint R. Minimum anesthetic concentration of sevoflurane with different xenon concentrations in swine. Anesth Analg 2003; 97:1364-1369. [PMID: 14570653 DOI: 10.1213/01.ane.0000081062.20894.d1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
UNLABELLED In a previous study, we described a partial antagonism of xenon (Xe) in combination with isoflurane. One hypothetical explanation suggested that Xe and isoflurane probably induced anesthesia via different pathways at the neuronal level. This warranted investigating the combination of Xe with other inhaled anesthetics to examine the relationship between Xe and volatile anesthetics in general. We therefore investigated the influence of Xe on the minimum alveolar concentration (MAC) of sevoflurane. The study was performed in 10 swine (weight 30.8 kg +/- 2.6, mean +/- SD) ventilated with xenon 0%, 15%, 30%, 40%, 50%, and 65% in oxygen. At each Xe concentration, various concentrations of sevoflurane were administered in a stepwise design. For each a supramaximal pain stimulus (claw clamp) was applied. The appearance of a withdrawal reaction was recorded. The sevoflurane MAC was defined as the end-tidal concentration required to produce a 50% response rate. At each Xe concentration, the animals' responses to the pain stimulus were categorized and a logistic regression model was fitted to the results to determine sevoflurane MAC. Sevoflurane MAC was decreased by inhalation of Xe in a linear manner from 2.53 with 0% Xe to 1.54 with 65% Xe. In contrast to Xe and isoflurane, the anesthetic effects of Xe and sevoflurane appear to be simply linear. IMPLICATIONS We investigated the influence of the anesthetic gas, xenon, on the minimum alveolar concentration (MAC) for the volatile anesthetic sevoflurane. The study was performed in 10 swine ventilated with fixed xenon and various concentrations of isoflurane. The sevoflurane MAC is decreased by inhalation of xenon in a linear relationship.
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Affiliation(s)
- Klaus E Hecker
- Departments of *Anesthesiology and †Medical Statistics, Universitätsklinikum der RWTH Aachen, Aachen, Germany, and the ‡Department of Anesthesiology and Intensive Care, Waldkrankenhaus Berlin, Berlin, Germany
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