Cranial Venous Outflow Under Lower Body Positive and Negative Pressure Conditions and Head-Up and -Down Tilts

ABSTRACT BACKGROUND Although there exists a large body of knowledge on the regulation of arterial cerebral hemodynamics, little is known about the cerebral venous outflow (CVO). METHODS In 19 healthy volunteers, the middle cerebral artery and the straight sinus were examined using transcranial Doppl...

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Bibliographic Details
Published in:	Journal of neuroimaging Vol. 19; no. 1; pp. 31 - 36
Main Authors:	Stolz, Erwin, Fox, Bettina C, Hoffmann, Oskar, Gerriets, Tibo, Blaes, Franz, Kraus, Jörg, Kaps, Manfred
Format:	Journal Article
Language:	English
Published:	Malden, USA Blackwell Publishing Inc 01-01-2009
Subjects:	Adult Autoregulation Blood Flow Velocity - physiology Blood Pressure Determination Cerebral veins Cerebrovascular Circulation - physiology Female Head tilt Head-Down Tilt Humans Lower Body Negative Pressure Lower body positive pressure Male Statistics, Nonparametric Tilt-Table Test Ultrasonography, Doppler, Transcranial Ultrasound Veins - diagnostic imaging
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Summary:	ABSTRACT BACKGROUND Although there exists a large body of knowledge on the regulation of arterial cerebral hemodynamics, little is known about the cerebral venous outflow (CVO). METHODS In 19 healthy volunteers, the middle cerebral artery and the straight sinus were examined using transcranial Doppler sonography. Arterial and venous mean flow velocities (aFVmean, vFVmean, respectively) were registered continuously while applying lower body positive (LBPP) or negative (LBNP) pressure of 30 mmHg and performing head‐down (–20°, HDT) and ‐up (+30°, HUT) tilt manoeuvres. The arterial blood pressure was registered simultaneously with a noninvasive finger blood pressure monitor. Relative changes in parameters compared to the proceeding no‐pressure, no‐tilt baseline were used for analysis. RESULTS While aFVmean did not change significantly, vFVmean inc reased during LBPP by 10.5 ± 2.9% and decreased during LBNP by 15.1 ± 3.5% (mean ± standard error of mean [SEM], P < .01). HUT resulted in a decrease in vFVmean by 25.5 ± 3.3% and HDT, in an increase by 7.8 ± 3.2% (P < .01) without alteration in aFVmean. This may imply a decrease of cerebral blood volume (CBV) during LBPP and HDT and an increase during LBNP and HUT. CONCLUSIONS CVO cannot be neglected when studying cerebral hemodynamics because it might affect the CBV.
Bibliography:	istex:5F4542932E5375A6D8A33E578E1F7873B90E527C ark:/67375/WNG-P30MQP67-H ArticleID:JON250 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	1051-2284 1552-6569
DOI:	10.1111/j.1552-6569.2008.00250.x