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Cranial Venous Outflow Under Lower Body Positive and Negative Pressure Conditions and Head‐Up and ‐Down Tilts
Author(s) -
Stolz Erwin,
Fox Bettina C,
Hoffmann Oskar,
Gerriets Tibo,
Blaes Franz,
Kraus Jörg,
Kaps Manfred
Publication year - 2009
Publication title -
journal of neuroimaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.822
H-Index - 64
eISSN - 1552-6569
pISSN - 1051-2284
DOI - 10.1111/j.1552-6569.2008.00250.x
Subject(s) - medicine , hemodynamics , head down tilt , anesthesia , mean arterial pressure , transcranial doppler , cerebral blood flow , blood pressure , cardiology , middle cerebral artery , lower body , blood volume , central venous pressure , venous return curve , intracranial pressure , cerebral autoregulation , heart rate , autoregulation , ischemia
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 (aFV mean , vFV mean , 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 aFV mean did not change significantly, vFV mean 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 vFV mean by 25.5 ± 3.3% and HDT, in an increase by 7.8 ± 3.2% ( P < .01) without alteration in aFV mean . 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.