Blood Flow Velocities in the Vertebral Veins of Healthy Subjects: A Duplex Sonographic Study

1999 ◽  
Vol 9 (4) ◽  
pp. 198-200 ◽  
Author(s):  
Olaf Hoffmann ◽  
Markus Weih ◽  
Thomas von Münster ◽  
Stephan Schreiber ◽  
Karl Max Einhäupl ◽  
...  
Keyword(s):  
Blood Flow ◽  
Healthy Subjects ◽  
Blood Flow Velocities ◽  
Flow Velocities

scholarly journals A Comparison of Regional Cerebral Blood Flow and Middle Cerebral Artery Blood Flow Velocities: Simultaneous Measurements in Healthy Subjects

1992 ◽  
Vol 12 (6) ◽  
pp. 1049-1054 ◽  
Author(s):  
Arve Dahl ◽  
David Russell ◽  
Rolf Nyberg-Hansen ◽  
Kjell Rootwelt
Keyword(s):  
Blood Flow ◽  
Healthy Subjects ◽  
Cerebral Arteries ◽  
Transcranial Doppler Ultrasound ◽  
Velocity Increase ◽  
Mental Activation ◽  
Middle Cerebral Arteries ◽  
Blood Flow Velocities ◽  
Perfusion Territory ◽  
Flow Velocities

Blood flow velocities were measured in both middle cerebral arteries (MCAs) of 36 healthy subjects using transcranial Doppler ultrasound. Measurements were first made using a hand-held probe. Velocities were then studied bilaterally with fixed probes under resting conditions and during simultaneous regional CBF (rCBF) measurements. A significant (p < 0.05) positive correlation was found between MCA flow velocities and rCBF in the estimated perfusion territory of this artery. The correlation coefficient was highest when the measurements were performed simultaneously (p < 0.001) or when velocities recorded with a hand-held probe were adjusted to take into account the significant velocity increase induced by the CBF study situation. The increased velocities during CBF measurements cannot be fully explained by the moderate but significant Pco2 increase. Other possible mechanisms are increased blood flow due to mental activation or MCA vasoconstriction secondary to stimulation of the sympathetic nervous system. The effect of mental activation and Pco2 differences should therefore be considered when comparing the results of repeated velocity and CBF measurements.

scholarly journals Comparison of Retinal Microvessel Blood Flow Velocities Acquired with Two Different Fields of View

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Jin Zhou ◽  
Min Li ◽  
Wan Chen ◽  
Ye Yang ◽  
Liang Hu ◽  
...  
Keyword(s):  
Blood Flow ◽  
Healthy Subjects ◽  
Conversion Factor ◽  
Retinal Function ◽  
Retinal Blood Flow ◽  
Retinal Function Imager ◽  
Blood Flow Velocities ◽  
Wide Fov ◽  
Retinal Arteriolar ◽  
Flow Velocities

To compare the different retinal blood flow velocities (BFVs) acquired with different fields of view (FOVs) using the retinal function imager (RFI), twenty eyes of twenty healthy subjects were enrolled in the study. Retinal microvessel BFV in the macula was acquired with both a wide FOV (35 degrees, 7.3 × 7.3 mm2) and a commonly used small FOV (20 degrees, 4.3 × 4.3 mm2). The 35-degree FOV was trimmed to be equivalent to the 20-degree FOV to compare the BFVs of the similar FOVs using different settings. With the 35-degree FOV, both retinal arteriolar and venular BFVs were significantly greater than the 20-degree FOV (P<0.001). When the 20-degree FOV was compared to the trimmed equivalent 20-degree FOV acquired using the 35-degree FOV, significant BFV differences were found in both the arterioles (P=0.029) and venules (P<0.001). This is the first study to compare retinal blood flow velocities acquired with different FOVs using RFI. The conversion factor from 35 degrees to 20 degrees is 0.95 for arteriolar BFV and 0.92 for venular BFV, which may be used for comparing BFVs acquired with different FOVs.

scholarly journals Simultaneous Assessment of Vasoreactivity Using Transcranial Doppler Ultrasound and Cerebral Blood Flow in Healthy Subjects

1994 ◽  
Vol 14 (6) ◽  
pp. 974-981 ◽  
Author(s):  
Arve Dahl ◽  
David Russell ◽  
Rolf Nyberg-Hansen ◽  
Kjell Rootwelt ◽  
Petter Mowinckel
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Healthy Subjects ◽  
Regional Cerebral Blood Flow ◽  
Cerebral Arteries ◽  
Repeated Measurements ◽  
Regional Cerebral Blood ◽  
Velocity Increase ◽  
Blood Flow Velocities ◽  
Flow Velocities

Blood flow velocities in both middle cerebral arteries and regional cerebral blood flow in their perfusion territories were measured simultaneously in 36 healthy subjects. In 20 subjects, the measurements were first performed under basal conditions and then repeated 15–20 min after an intravenous injection of 1 g of acetazolamide. Reproducibility of simultaneous blood flow and velocity measurements was tested by examining 16 subjects on two occasions under basal conditions with an interval of 20 min. Relatively good reproducibility was found for repeated measurements of velocity and blood flow, being best when side-to-side asymmetry was assessed. The increase in blood flow velocities after acetazolamide was symmetrical (right side, 34.2%; and left side, 35.5%), and the velocity increase was significantly correlated with basal values. The increase in cerebral blood flow was also symmetrical (right side, 29.8%; left side, 30.1%) but not correlated with basal flow values. No significant relationship was found between velocity increase and increase in regional cerebral blood flow. This finding is probably not only due to methodological inaccuracies but may suggest that acetazolamide has an effect on the diameter of the middle cerebral artery or on the magnitude of this artery's perfusion territory. This study supports the use of acetazolamide for assessing cerebral vasoreactivity following the definition of lower limits for velocity and flow increase and for asymmetry of the response.

Patterns of Cerebral Blood Flow and Systemic Hemodynamics During Arithmetic Processing

2008 ◽  
Vol 22 (2) ◽  
pp. 81-90 ◽  
Author(s):  
Natalie Werner ◽  
Neval Kapan ◽  
Gustavo A. Reyes del Paso
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Time Course ◽  
Doppler Sonography ◽  
Transcranial Doppler Sonography ◽  
Systemic Hemodynamics ◽  
Heart Period ◽  
Blood Flow Velocities ◽  
Flow Velocities

The present study explored modulations in cerebral blood flow and systemic hemodynamics during the execution of a mental calculation task in 41 healthy subjects. Time course and lateralization of blood flow velocities in the medial cerebral arteries of both hemispheres were assessed using functional transcranial Doppler sonography. Indices of systemic hemodynamics were obtained using continuous blood pressure recordings. Doppler sonography revealed a biphasic left dominant rise in cerebral blood flow velocities during task execution. Systemic blood pressure increased, whereas heart period, heart period variability, and baroreflex sensitivity declined. Blood pressure and heart period proved predictive of the magnitude of the cerebral blood flow response, particularly of its initial component. Various physiological mechanisms may be assumed to be involved in cardiovascular adjustment to cognitive demands. While specific contributions of the sympathetic and parasympathetic systems may account for the observed pattern of systemic hemodynamics, flow metabolism coupling, fast neurogenic vasodilation, and cerebral autoregulation may be involved in mediating cerebral blood flow modulations. Furthermore, during conditions of high cardiovascular reactivity, systemic hemodynamic changes exert a marked influence on cerebral blood perfusion.

scholarly journals Effect of positioning from supine and left lateral positions to left lateral tilt on maternal blood flow velocities and waveforms in full-term parturients

Anaesthesia ◽  
2012 ◽  
Vol 67 (8) ◽  
pp. 936-936 ◽  
Author(s):  
P. Kundra ◽  
J. Velraj ◽  
U. Amirthalingam ◽  
S. Habeebullah ◽  
K. Yuvaraj ◽  
...  
Keyword(s):  
Blood Flow ◽  
Maternal Blood ◽  
Full Term ◽  
Lateral Tilt ◽  
Blood Flow Velocities ◽  
Flow Velocities

scholarly journals Acute Effect of Hypervolemic Hemodilution on Retrobulbar Hemodynamics in Anterior Ischemic Optic Neuropathy

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Marion Bienert ◽  
Niklas Plange ◽  
Andreas Remky ◽  
Kay Oliver Arend ◽  
David Kuerten
Keyword(s):  
Blood Flow ◽  
Hydroxyethyl Starch ◽  
Optic Neuropathy ◽  
Acute Effect ◽  
Anterior Ischemic Optic Neuropathy ◽  
Ischemic Optic Neuropathy ◽  
Hypervolemic Hemodilution ◽  
Blood Flow Velocities ◽  
Retrobulbar Hemodynamics ◽  
Flow Velocities

Purpose.Ischemic ocular disorders may be treated by hypervolemic hemodilution. The presumed therapeutic benefit is based on a volume effect and improved rheological factors. The aim was to investigate the acute effect of intravenous hydroxyethyl starch on retrobulbar hemodynamics in patients with nonarteritic anterior ischemic optic neuropathy (NAION).Methods.24 patients with acute NAION were included. Retrobulbar hemodynamics were measured using color Doppler imaging before and 15 min after intravenous infusion of 250 cc 10% hydroxyethyl starch (HES). Peak systolic velocity (PSV), end diastolic velocity (EDV), and Pourcelot’s resistive index (RI) were measured in the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (PCAs).Results.After infusion of HES blood flow velocities significantly increased in the CRA (PSV from7.53±2.33to8.32±2.51  (p<0.001); EDV from2.16±0.56to2.34±0.55  (p<0.05)) and in the PCAs (PSV from7.18±1.62to7.56±1.55  (p<0.01); EDV from2.48±0.55to2.66±0.6 cm/sec (p<0.01)). The RI of all retrobulbar vessels remained unaffected. Blood pressure and heart rate remained unchanged.Conclusions.Hypervolemic hemodilution has an acute effect on blood flow velocities in the CRA and PCAs in NAION patients. Increased blood flow in the arteries supplying the optic nerve head may lead to a better perfusion in NAION patients. This trial is registered withDRKS00012603.

Doppler Assessment of Human Neonatal Gut Blood Flow Velocities

1992 ◽  
Vol 15 (1) ◽  
pp. 6-12 ◽  
Author(s):  
R. C. Coombs ◽  
M. E. I. Morgan ◽  
G. M. Durbin ◽  
I. W. Booth ◽  
A. S. McNeish
Keyword(s):  
Blood Flow ◽  
Blood Flow Velocities ◽  
Flow Velocities
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