| Critical closing pressure explains cerebral hemodynamics during the Valsalva maneuver. | |
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MedLine Citation:
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PMID: 9931207 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The Valsalva maneuver (VM), a voluntary increase in intrathoracic pressure of approximately 40 mmHg, has been used to examine cerebral autoregulation (CA). During phase IV of the VM there are pronounced changes in mean arterial blood pressure (MABP), pulse interval, and cerebral blood flow (CBF), but the changes in CBF are of a much greater magnitude than those seen in MABP, a finding to date attributed to either a delay in activation of the CA mechanism or the inability of this mechanism to cope with the size and speed of the blood pressure changes involved. These changes in CBF also precede those in MABP, a pattern of events not explained by the physiological process of CA. Measurements of CBF velocity (transcranial Doppler) and MABP (Finapres) were performed in 53 healthy volunteers (aged 31-80 yr). By calculating beat-to-beat values of critical closing pressure (CCP) during the VM, we have found that this parameter suddenly drops at the start of phase IV, providing a coherent explanation for the large increase in CBF. If CCP is included in the estimation of cerebrovascular resistance, a temporal pattern more consistent with an autoregulatory response to the MABP overshoot is also found. CCP is intricately involved in the control of CBF during the VM and should be considered in the assessment of CA. |
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Authors:
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S L Dawson; R B Panerai; J F Potter |
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Publication Detail:
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Type: Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: 86 ISSN: 8750-7587 ISO Abbreviation: J. Appl. Physiol. Publication Date: 1999 Feb |
Date Detail:
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Created Date: 1999-03-22 Completed Date: 1999-03-22 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 675-80 Citation Subset: IM |
Affiliation:
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University Department of Medicine for the Elderly, The Glenfield Hospital, Leicester LE3 9QP, United Kingdom. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Aged Aged, 80 and over Blood Pressure / physiology* Cerebrovascular Circulation / physiology* Female Homeostasis / physiology Humans Male Middle Aged Ultrasonography, Doppler, Transcranial Valsalva Maneuver / physiology* Vascular Resistance / physiology |
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