| The effect on cerebral tissue oxygenation index of changes in the concentrations of inspired oxygen and end-tidal carbon dioxide in healthy adult volunteers. | |
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MedLine Citation:
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PMID: 19690266 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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BACKGROUND: A variety of near-infrared spectroscopy devices can be used to make noninvasive measurements of cerebral tissue oxygen saturation (ScO2). The ScO2 measured by the NIRO 300 spectrometer (Hamamatsu Photonics, Japan) is called the cerebral tissue oxygenation index (TOI) and is an assessment of the balance between cerebral oxygen delivery and utilization. We designed this study to investigate the effect of systemic and intracranial physiological changes on TOI. METHODS: Fifteen healthy volunteers were studied during isocapneic hyperoxia and hypoxemia, and normoxic hypercapnea and hypocapnea. Absolute cerebral TOI and changes in oxy- and deoxyhemoglobin concentrations were measured using a NIRO 300 spectrometer. Changes in arterial oxygen saturation (SaO2), ETCO2, heart rate, mean arterial blood pressure (MBP), and middle cerebral artery blood flow velocity (Vmca) were also measured during these physiological challenges. Changes in cerebral blood volume (CBV) were subsequently calculated from changes in total cerebral hemoglobin concentration. RESULTS: Baseline TOI was 67.3% with an interquartile range (IQR) of 65.2%-71.9%. Hypoxemia was associated with a median decrease in TOI of 7.1% (IQR -9.1% to -5.4%) from baseline (P < 0.0001) and hyperoxia with a median increase of 2.3% (IQR 2.0%-2.5%) (P < 0.0001). Hypocapnea caused a reduction in TOI of 2.1% (IQR -3.3% to -1.3%) from baseline (P < 0.0001) and hypercapnea an increase of 2.6% (IQR 1.4%-3.7%) (P < 0.0001). Changes in SaO2 (P < 0.0001), ETCO2 (P < 0.0001), CBV (P = 0.0003), and MBP (P = 0.03) were significant variables affecting TOI. Changes in Vmca (P = 0.7) and heart rate (P = 0.2) were not significant factors. CONCLUSION: TOI is an easy-to-monitor variable that provides real-time, multisite, and noninvasive assessment of the balance between cerebral oxygen delivery and utilization. However, TOI is a complex variable that is affected by SaO2 and ETCO2, and, to a lesser extent, by MBP and CBV. Clinicians need to be aware of the systemic and cerebral physiological changes that can affect TOI to interpret changes in this variable during clinical monitoring. |
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Authors:
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Martin M Tisdall; Christopher Taylor; Ilias Tachtsidis; Terence S Leung; Clare E Elwell; Martin Smith |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Anesthesia and analgesia Volume: 109 ISSN: 1526-7598 ISO Abbreviation: Anesth. Analg. Publication Date: 2009 Sep |
Date Detail:
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Created Date: 2009-08-19 Completed Date: 2009-09-09 Revised Date: 2010-09-27 |
Medline Journal Info:
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Nlm Unique ID: 1310650 Medline TA: Anesth Analg Country: United States |
Other Details:
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Languages: eng Pagination: 906-13 Citation Subset: AIM; IM |
Affiliation:
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Department of Neuroanaesthesia and Neurocritical Care, The National Hospital for Neurology and Neurosurgery, University College London Hospitals, London, UK. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Anoxia / pathology Blood Pressure Carbon Dioxide / metabolism Cerebrovascular Circulation / physiology* Female Humans Hypercapnia / pathology Hyperoxia / pathology Kinetics Male Oxygen / metabolism Oxygen Consumption / physiology Spectrophotometry / methods Tidal Volume |
| Grant Support | |
ID/Acronym/Agency:
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075608//Wellcome Trust; 075608//Wellcome Trust; //Department of Health |
| Chemical | |
Reg. No./Substance:
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124-38-9/Carbon Dioxide; 7782-44-7/Oxygen |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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