| Effects of CO2 on dynamic cerebral autoregulation measurement. | |
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MedLine Citation:
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PMID: 10475580 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Arterial pCO2 is known to influence cerebral autoregulation but its effect on the dynamic relationship between mean arterial blood pressure (ABP) and mean cerebral blood flow velocity (CBFV), obtained from spontaneous fluctuations in ABP, has not been established. In 16 normal subjects, ABP was measured non-invasively (Finapres), CBFV was estimated with Doppler ultrasound in the middle cerebral artery, and end-tidal CO2 (EtCO2) was measured with an infrared capnograph. Recordings were made before, during and after breathing a mixture of 5% CO2 in air. The coherence function, amplitude and phase frequency responses, and impulse and step responses for the effects of ABP on CBFV were calculated by spectral analysis of beat-to-beat changes in mean ABP and CBFV before (mean CO2 5.55 +/- 0.38 kPa), during (6.43 +/- 0.31 kPa) and after 5% CO2 (5.43 +/- 0.26 kPa). During 5% CO2, the coherence function and the amplitude frequency response were significantly increased for frequencies below 0.05 Hz and the phase was reduced for the frequency range 0.02-0.1 Hz. The impulse and step responses indicated that 5% CO2 reduces the efficiency of the autoregulatory mechanism. A 20.7% average increase in CBFV induced by a 14.4% increase in EtCO2 was found to be mediated by a 25.9% reduction in critical closing pressure, while the change in resistance area product was non-significant. |
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Authors:
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R B Panerai; S T Deverson; P Mahony; P Hayes; D H Evans |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Physiological measurement Volume: 20 ISSN: 0967-3334 ISO Abbreviation: Physiol Meas Publication Date: 1999 Aug |
Date Detail:
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Created Date: 1999-10-08 Completed Date: 1999-10-08 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 9306921 Medline TA: Physiol Meas Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 265-75 Citation Subset: IM |
Affiliation:
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Division of Medical Physics, Faculty of Medicine, University of Leicester, Leicester Royal Infirmary, UK. rp9@le.ac.uk |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Blood Flow Velocity Blood Pressure / drug effects Brain / blood supply* Carbon Dioxide / blood*, pharmacology Cerebral Arteries / ultrasonography Heart Rate / drug effects Homeostasis Humans Middle Aged Regional Blood Flow Respiration |
| Chemical | |
Reg. No./Substance:
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124-38-9/Carbon Dioxide |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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