scholarly journals Portable, non-invasive video imaging of retinal blood flow dynamics

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Kyoung-A Cho ◽  
Abhishek Rege ◽  
Yici Jing ◽  
Akash Chaurasia ◽  
Amit Guruprasad ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cardiac Cycle ◽  
Venous Blood ◽  
Retinal Blood Flow ◽  
High Temporal Resolution ◽  
Venous Blood Flow ◽  
Head Region ◽  
Flow Measurements ◽  
Non Invasive ◽  
Temporal Waveform

AbstractRetinal blood flow (RBF) information has the potential to offer insight into ophthalmic health and disease that is complementary to traditional anatomical biomarkers as well as to retinal perfusion information provided by fluorescence or optical coherence tomography angiography (OCT-A). The present study was performed to test the functional attributes and performance of the XyCAM RI, a non-invasive imager that obtains and assesses RBF information. The XyCAM RI was installed and used in two different settings to obtain video recordings of the blood flow in the optic nerve head region in eyes of healthy subjects. The mean blood flow velocity index (BFVi) in the optic disc and in each of multiple arterial and venous segments was obtained and shown to reveal a temporal waveform with a peak and trough that correlates with a cardiac cycle as revealed by a reference pulse oximeter (correlation between respective peak-to-peak distances was 0.977). The intra-session repeatability of the XyCAM RI was high with a coefficient of variation (CV) of 1.84 ± 1.13% across both sites. Artery-vein comparisons were made by estimating, in a pair of adjacent arterial and venous segments, various temporal waveform metrics such as pulsatility index, percent time in systole and diastole, and change in vascular blood volume over a cardiac cycle. All arterial metrics were shown to have significant differences with venous metrics (p < 0.001). The XyCAM RI, therefore, by obtaining repeatable blood flow measurements with high temporal resolution, permits the differential assessment of arterial and venous blood flow patterns in the retina that may facilitate research into disease pathophysiology and biomarker development for diagnostics.

Neuromuscular electrical stimulation for thromboprophylaxis: A systematic review

2015 ◽  
Vol 30 (9) ◽  
pp. 589-602 ◽  
Author(s):  
S Hajibandeh ◽  
S Hajibandeh ◽  
GA Antoniou ◽  
JRH Scurr ◽  
F Torella
Keyword(s):  
Systematic Review ◽  
Blood Flow ◽  
Electrical Stimulation ◽  
Venous Thromboembolism ◽  
Venous Blood ◽  
Neuromuscular Electrical Stimulation ◽  
Current Evidence ◽  
Venous Blood Flow ◽  
Flow Measurements ◽  
Blood Flow Measurements

Objective To evaluate the effect of neuromuscular electrical stimulation on lower limb venous blood flow and its role in thromboprophylaxis. Method Systematic review of randomised and non-randomised studies evaluating neuromuscular electrical stimulation, and reporting one or more of the following outcomes: incidence of venous thromboembolism, venous blood flow and discomfort profile. Results Twenty-one articles were identified. Review of these articles showed that neuromuscular electrical stimulation increases venous blood flow and is generally associated with an acceptable tolerability, potentially leading to good patient compliance. Ten comparative studies reported DVT incidence, ranging from 2% to 50% with neuromuscular electrical stimulation and 6% to 47.1% in controls. There were significant differences, among included studies, in terms of patient population, neuromuscular electrical stimulation delivery, diagnosis of venous thromboembolism and blood flow measurements. Conclusion Neuromuscular electrical stimulation increases venous blood flow and is well tolerated, but current evidence does not support a role for neuromuscular electrical stimulation in thromboprophylaxis. Randomised controlled trials are required to investigate the clinical utility of neuromuscular electrical stimulation in this setting.

Non-invasive measurement of azygos venous blood flow using magnetic resonance

1995 ◽  
Vol 22 (4) ◽  
pp. 399-403 ◽  
Author(s):  
David J. Lomas ◽  
Michael P. Hayball ◽  
David Parry Jones ◽  
Clare Sims ◽  
Michael E.D. Allison ◽  
...  
Keyword(s):  
Blood Flow ◽  
Magnetic Resonance ◽  
Venous Blood ◽  
Venous Blood Flow ◽  
Non Invasive ◽  
Invasive Measurement

scholarly journals Arterio-Venous Branchial Blood Flow in the Atlantic Cod Gadus Morhua

1992 ◽  
Vol 165 (1) ◽  
pp. 73-84 ◽  
Author(s):  
LENA SUNDIN ◽  
STEFAN NILSSON
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Atlantic Cod ◽  
Vascular System ◽  
Venous Blood ◽  
Venous Blood Flow ◽  
Venous Flow ◽  
Flow Measurements ◽  
Vasomotor Function

We have estimated the branchial venous blood flow in the Atlantic cod by direct single-crystal Doppler blood flow measurements in vivo. In the undisturbed animal, this flow amounts to 1.7 ml min−1 kg−1, which corresponds to about 8 % of the cardiac output. Studies of both an isolated perfused gill apparatus in situ and simultaneous measurements of cardiac output and branchial venous flow in vivo were made to assess the effects of some putative vasoregulatory substances. Adrenaline dilates the arterio-arterial pathway and constricts the arterio-venous pathway, thus decreasing branchial venous drainage. 5-Hydroxytryptamine (5-HT), in contrast, produced marked vasoconstriction in the arterio-arterial pathway of the branchial vasculature, increasing the branchial venous blood flow. Cholecystokinin-8 (CCK-8) and caerulein produced similar cardiovascular effects, with marked constriction of both arterio-arterial and arterio-venous pathways. The study demonstrates the ability of the vascular system of the gills to regulate the distribution of branchial blood flow, and summarizes the vasomotor effects of some substances with possible vasomotor function in the cod gills.

scholarly journals OP19.11: Umbilical venous blood flow measurements: comparison between free and intra-abdominal portion

2009 ◽  
Vol 34 (S1) ◽  
pp. 124-124
Author(s):  
J. Carrillo ◽  
M. Yamamoto ◽  
D. Pedraza ◽  
H. Munoz ◽  
P. Valentini ◽  
...  
Keyword(s):  
Blood Flow ◽  
Venous Blood ◽  
Venous Blood Flow ◽  
Flow Measurements ◽  
Blood Flow Measurements ◽  
Abdominal Portion

scholarly journals Investigation of a non-invasive venous blood flow measurement device

2019 ◽  
Vol 5 (1) ◽  
pp. 179-182
Author(s):  
Kent Stewart ◽  
Simon Dangelmaier ◽  
Peter Pott ◽  
Jens Anders
Keyword(s):  
Blood Flow ◽  
Mass Flow ◽  
Flow Rate ◽  
Flow Measurement ◽  
Medical Condition ◽  
Venous Blood ◽  
Thermal Mass ◽  
Venous Blood Flow ◽  
Flow Meter ◽  
Non Invasive

AbstractVenous blood circulation can be restricted due to various conditions commonly indicating a related medical condition. However, current non-invasive methods for determining venous blood flow are limited to be either very inaccurate or expensive. Alternatively, a method to measure sap flow non-invasively in trees is through thermal mass measurement principles. This paper investigates applying the thermal mass flow measurement principle to determine venous blood flow. A simplified finite element model (FEM) and simulation are created to determine the operating behavior and expected response of a thermal mass flow meter with venous blood flow under the skin. An initial prototype of a thermal mass venous blood flow meter is designed using a Peltier-element and RTD thermistors. Initial tests were done on N = 8 subjects identifying the presence of blood flow and, testing the devices basic functionality and performance. The simplified FEM model of venous blood flow proved the thermal mass blood flow device is feasible, and determined the initial characteristics of the first prototype. The initial prototype proved to be functional detecting rises in temperature downstream of +1.4 K (0.8 - 1.8 inter- quartile range) when the blood flow was released (t = 90 s after release), compared to when blood was not flowing. The initial prototype proved to be able to detect the presence of blood flow in all subjects. However, further work is required to increase the differences in temperature values or gradient measured for a change in flow rate so the actual flow rate can be determined.

scholarly journals Review of the plethysmographic methods for studying hemodynamic disorders in patients with chronic lower extremites venous diseases

2020 ◽  
pp. 58-70
Author(s):  
A. B. Sannikov ◽  
V. M. Emelyanenko ◽  
I. V. Drozdova
Keyword(s):  
Blood Flow ◽  
Chronic Venous Insufficiency ◽  
Venous Insufficiency ◽  
Venous Blood ◽  
Lower Extremities ◽  
Venous Blood Flow ◽  
Residual Volume ◽  
Venous Outflow ◽  
Non Invasive ◽  
Venous Diseases

Plethysmography as a method for studying peripheral circulatory system was first proposed by wletney in 1953. In Russia, the first most significant research studies on the feasibility of plethysmography in studying peripheral blood flow and circulatory physiology taken together were conducted at the St. Petersburg Pavlov Institute of Physiology in 1961. From this time onwards, the possibilities of plethysmography as a non-invasive objective method for the diagnosis of hemodynamic disorders, particularly in arterial pathology, were studied intensively. These parameters were not determined for the venous blood flow, but in 1980s the authors were able to establish plethysmographic criteria not only for various forms of venous pathology, but also for degrees of chronic venous insufficiency using a device significantly improved by V.N. Pavlov and V.E. Maslov.The purpose of this publication is to analyze the literature data on the use of aerial plethysmography and photoplethysmography in the study of hemodynamic disorders in patients with chronic diseases of the veins of the lower extremities. At present, in order to assess the venous blood flow in condition of air plethysmography, indicators of functional venous volume (VV), maximum venous outflow (MVO), venous filling index (VFI), evacuation volume (EV) and residual volume (RV), as well as an integral indicator – residual volume fraction (RVF) are determined in the world. A venous reflux test (VRT) is performed as part of photoplethysmography. The data published today show the high statistical reliability of the comparative analysis and the great scientific significance of the research. According to many foreign authors the use of plethysmographic methods of diagnosis allow to assess violations of venous blood flow in patients with chronic venous diseases of various clinical classes according to CEAP more precisely and to give a global assessment of disorders of the venous outflow from thrombotic occlusion of segmental to hypervolemia in patients with varicose veins in different forms of manifestations of chronic venous insufficiency. The analysis of the literature data allows to make a conclusion about the prospects of further research using these non-invasive methods of evaluation of venous blood flow in the lower extremities.

Norethynodrel with mestranol and venous blood flow

JAMA ◽  
1966 ◽  
Vol 198 (7) ◽  
pp. 784-785 ◽  
Author(s):  
A. Neistadt
Keyword(s):  
Blood Flow ◽  
Venous Blood ◽  
Venous Blood Flow
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