Cross-sectional vascular blood flow shear rate using Doppler ultrasound

1999 ◽  
Author(s):  
James B. Farison ◽  
Garett A. Begeman ◽  
Sergio X. Salles-Cunha ◽  
Hugh G. Beebe
Keyword(s):  
Blood Flow ◽  
Shear Rate ◽  
Doppler Ultrasound ◽  
Flow Shear ◽  
Cross Sectional

Improved determination of vascular blood-flow shear rate using Doppler ultrasound

1997 ◽  
Author(s):  
James B. Farison ◽  
Garett A. Begeman ◽  
Sergio X. Salles-Cunha ◽  
Hugh G. Beebe
Keyword(s):  
Blood Flow ◽  
Shear Rate ◽  
Doppler Ultrasound ◽  
Flow Shear

Calf blood flow and posture: Doppler ultrasound calibrated by plethysmography

1992 ◽  
Vol 72 (5) ◽  
pp. 1668-1674 ◽  
Author(s):  
B. E. Van Leeuwen ◽  
J. Lubbers ◽  
G. J. Barendsen ◽  
L. de Pater
Keyword(s):  
Blood Flow ◽  
Doppler Ultrasound ◽  
Doppler Frequency ◽  
Calibration Method ◽  
Rhythmic Contraction ◽  
Cross Sectional ◽  
Calf Blood Flow ◽  
Doppler Signals ◽  
Heart Cycle ◽  
The Relationship

A procedure was developed that enables measurement of rapid variations in calf blood flow during voluntary rhythmic contraction of the calf muscles in supine, sitting, and standing positions. During the exercise, maximum blood velocity is measured by Doppler ultrasound equipment in the popliteal artery. The Doppler signals are calibrated by plethysmography to enable calculation of blood flow during exercise in ml.100 ml-1.min-1. Knowledge of the cross-sectional area of the vessel and the angle of insonation is not required in this procedure. Evaluation of the calibration method with 10 healthy volunteers showed that for each subject a new calibration was necessary after a change in posture; the relationship between the blood flow and the maximum Doppler frequency averaged over one heart cycle was linear for each calibration.

How to carry out monthly blood flow surveillance of fistula in large-scale hemodialysis units: A cross-sectional study

2020 ◽  
pp. 112972982092393
Author(s):  
Ya-wen Mo ◽  
Chun-yan Sun ◽  
Li Song ◽  
Li-fang Zhou ◽  
Ting-ting Zhuang ◽  
...  
Keyword(s):  
Blood Flow ◽  
Arteriovenous Fistula ◽  
Doppler Ultrasound ◽  
Radial Artery ◽  
Brachial Artery ◽  
Dilution Technique ◽  
Cross Sectional ◽  
Duplex Doppler Ultrasound ◽  
Duplex Doppler ◽  
Artery Flow

Background: The important effect of regular blood flow surveillance on arteriovenous fistula maintenance is emphasized. The ultrasonic dilution technique for blood flow surveillance can be performed during hemodialysis, but there are some limitations. Blood flow is traditionally measured by duplex Doppler ultrasound during the nondialysis period. However, the surveillance workload for arteriovenous fistula has increased with the rapid increase in the hemodialysis population size. Efficient methods for blood flow surveillance during hemodialysis are needed. Methods: Eighty-four hemodialysis patients with a forearm radiocephalic arteriovenous fistula were enrolled in this cross-sectional study. Each received blood flow measurements using ultrasonic dilution technique and duplex Doppler ultrasound during hemodialysis. Duplex Doppler ultrasound measurements included the blood flow of the brachial artery and radial artery. The correlations between these variables were analyzed. Results: The correlation coefficients ( r) between flow measured by ultrasonic dilution technique and brachial artery flow measured by duplex Doppler ultrasound, between flow measured by ultrasonic dilution technique and radial artery flow measured by duplex Doppler ultrasound, and between brachial artery flow and radial artery flow measured by duplex Doppler ultrasound were 0.724, 0.784, and 0.749, respectively (all p < 0.001). Conclusion: Blood flow measured by ultrasonic dilution technique was positively correlated with blood flow measured by duplex Doppler ultrasound during hemodialysis, suggesting that duplex Doppler ultrasound can be used to monitor the trends in the blood flow of the brachial artery and radial artery for timely intervention to improve patency during hemodialysis.

scholarly journals The Effects of Micro-vessel Curvature Induced Elongational Flows on Platelet Adhesion

2021 ◽  
Author(s):  
Christian J. Spieker ◽  
Gábor Závodszky ◽  
Clarisse Mouriaux ◽  
Max van der Kolk ◽  
Christian Gachet ◽  
...  
Keyword(s):  
Blood Flow ◽  
Shear Rate ◽  
Blood Cells ◽  
Platelet Adhesion ◽  
Wall Shear Rate ◽  
Cross Sectional ◽  
Layer Width ◽  
Elongational Flows ◽  
Wall Shear ◽  
Vessel Curvature

AbstractThe emerging profile of blood flow and the cross-sectional distribution of blood cells have far reaching biological consequences in various diseases and vital internal processes, such as platelet adhesion. The effects of several essential blood flow parameters, such as red blood cell free layer width, wall shear rate, and hematocrit on platelet adhesion were previously explored to great lengths in straight geometries. In the current work, the effects of channel curvature on cellular blood flow are investigated by simulating the accurate cellular movement and interaction of red blood cells and platelets in a half-arc channel for multiple wall shear rate and hematocrit values. The results show significant differences in the emerging shear rate values and distributions between the inner and outer arc of the channel curve, while the cell distributions remain predominantly uninfluenced. The simulation predictions are also compared to experimental platelet adhesion in a similar curved geometry. The inner side of the arc shows elevated platelet adhesion intensity at high wall shear rate, which correlates with increased shear rate and shear rate gradient sites in the simulation. Furthermore, since the platelet availability for binding seems uninfluenced by the curvature, these effects might influence the binding mechanics rather than the probability. The presence of elongational flows is detected in the simulations and the link to increased platelet adhesion is discussed in the experimental results.

scholarly journals A microfluidic bleeding model to investigate the effects of blood flow shear on microvascular hemostasis

Friction ◽  
2021 ◽  
Author(s):  
Xiangyu Hu ◽  
Haosheng Chen ◽  
Jiang Li ◽  
Kuilin Meng ◽  
Yuming Wang ◽  
...  
Keyword(s):  
Blood Flow ◽  
Platelet Aggregation ◽  
Shear Rate ◽  
Vascular Trauma ◽  
Prediction Methods ◽  
Flow Shear ◽  
Reliable Prediction ◽  
Life Threatening

AbstractHemorrhage is the phenomenon of blood loss caused by vascular trauma or other pathological reasons, which is life-threatening in severe cases. Because microhemorrhage is difficult to visually monitor and pre-treat in vivo, it is necessary to establish in vitro prediction methods to study the hemostasis mechanism in different physiological environments. In this study, a microfluidic bleeding model was developed to investigate the effect of blood flow shear on microvascular hemostasis. The results indicated that the regulation of blood shear rate on platelet aggregation affected the growth and morphology of hemostatic thrombus, and finally regulated the process of hemostasis. This in vitro model is significant to studies on hemostatic mechanisms, a reliable prediction of microhemorrhages, and an adjustment of the treatment scheme.

Beat-by-beat forearm blood flow with Doppler ultrasound and strain-gauge plethysmography

1995 ◽  
Vol 79 (3) ◽  
pp. 713-719 ◽  
Author(s):  
M. E. Tschakovsky ◽  
J. K. Shoemaker ◽  
R. L. Hughson
Keyword(s):  
Blood Flow ◽  
Doppler Ultrasound ◽  
Strain Gauge ◽  
Forearm Blood Flow ◽  
Venous Occlusion ◽  
Voluntary Contraction ◽  
Cross Sectional ◽  
Strain Gauge Plethysmography ◽  
Regression Parameters ◽  
Wide Range

Simultaneous Doppler ultrasound estimates of brachial artery mean blood velocity (MBV) and venous occlusion strain-gauge plethysmography measures of forearm blood flow (FBF) were performed to determine the beat-by-beat relationship between the two methods and provide a method for flow calibration of Doppler MBV estimates. Such a calibration of Doppler MBV eliminates the need for knowledge of vessel cross-sectional area and angle of insonation while allowing for the quantification of limb blood flow. Six healthy subjects (5 men and 1 woman) performed 40 s of isometric forearm contraction at 35% maximal voluntary contraction with arterial inflow occluded. This resulted in elevated blood flow on relaxation and cuff deflation, and simultaneous beat-by-beat Doppler MBV and strain-gauge FBF measurements were then made over a period of 2–3 min as flow gradually decreased to resting levels. The r2 values for the fitted regression lines over a wide range of flows ranged from 0.87 to 0.98, and the mean square error terms ranged from 0.88 to 3.07 ml.100 ml-1.min-1. Significant day-to-day variation of the fitted regression parameters within subjects indicated that quantitative estimates of FBF from Doppler MBV require a calibration to be performed for each experiment. The finding of a strong linear relationship between Doppler MBV and venous occlusion strain-gauge plethysmography, as well as the marked beat-by-beat effect of cuff inflation on blood flow, confirms the importance of calibration on the same beats, not on adjacent segments of beats.

Blood Flow Pattern and Anastomotic Compliance for Interrupted versus Continuous Coronary Bypass Grafts

2005 ◽  
Vol 6 (2) ◽  
pp. 65 ◽  
Author(s):  
Marc Gerdisch ◽  
Thomas Hinkamp ◽  
Stephen D. Ainsworth
Keyword(s):  
Blood Flow ◽  
Vessel Wall ◽  
Coronary Bypass ◽  
Bypass Grafts ◽  
Cross Sectional ◽  
Coronary Bypass Grafts ◽  
Geometric Consistency ◽  
Suturing Technique ◽  
Suturing Techniques ◽  
Key Indicators

<P>Background: Use of the interrupted coronary anastomosis has largely been abandoned in favor of the more rapid continuous suturing technique. The Coalescent U-CLIP anastomotic device allows the surgeon to create an interrupted distal anastomosis in the same amount of time that it would take to create a continuous anastomosis. This acute bovine study examined the effect of the anastomotic technique on blood flow and vessel wall function. </P><P>Methods: End-to-side coronary anastomoses were created in an open chest bovine model using the left and right internal thoracic arteries and the left anterior descending coronary artery. All other variables except suturing technique were carefully controlled. In each animal, one anastomosis was completed using a continuous suturing technique and the other was performed in an interrupted fashion using the Coalescent U-CLIP anastomotic device. Volumetric flow curves through each graft were analyzed using key indicators of anastomotic quality, and anastomotic compliance was evaluated using intravascular ultrasound. Luminal castings were created of each vessel to examine the interior surface of each anastomosis for constrictions and deformities. </P><P>Results: The interrupted anastomoses created with the Coalescent U-CLIP anastomotic device showed significant differences with respect to anastomotic compliance, pulsatility index, peak flow, and percentage of diastolic flow. The cross-sectional area and degree of luminal deformity were also different for the two suturing techniques. </P><P>Conclusions: In this acute bovine model, interrupted coronary anastomoses demonstrated superior geometric consistency and greater physiologic compliance than did continuously sutured anastomoses. The interrupted anastomosis also caused fewer disturbances to the flow waveform, behaving similarly to a normal vessel wall. The combination of these effects may influence both acute and long-term patency of the coronary bypass grafts.</P>

Optimal parameters of blood flow restriction and resistance training on quadriceps strength and cross-sectional area and pain in knee osteoarthritis

2021 ◽  
pp. 1-10
Author(s):  
Waleed S. Mahmoud ◽  
Ahmed Osailan ◽  
Ahmed S. Ahmed ◽  
Ragab K. Elnaggar ◽  
Nadia L. Radwan
Keyword(s):  
Blood Flow ◽  
Resistance Training ◽  
Knee Osteoarthritis ◽  
Quadriceps Strength ◽  
Sectional Area ◽  
Occlusion Pressure ◽  
Total Occlusion ◽  
Cross Sectional ◽  
Flow Restriction ◽  
Low Intensity

BACKGROUND: Knee osteoarthritis (KOA) is one of the most common chronic diseases impacting millions of elderly people. OBJECTIVES: The study compared the effects of two intensities of partial blood flow restriction (BFR) with low-intensity resistance training on quadriceps strength and cross-sectional area (CSA), and pain in people with knee osteoarthritis (PwKOA). METHODS: Thirty-five PwKOA, aged 50–65, participated. Quadriceps CSA was measured by ultrasonography, quadriceps strength – by isokinetic dynamometry and pain by VAS. These outcome variables were obtained at the beginning of the study and re-evaluated eight weeks after the intervention. RESULTS: An interaction effect was present for quadriceps CSA (P= 0.042) and quadriceps strength (P= 0.006), showing that using 70% of total occlusion pressure with 30% 1RM had a more significant effect. Knee pain improved significantly through the main effect of BFR (P< 0.001), and low-intensity resistance training (P= 0.011). Pain improved more at 70% of total occlusion pressure, with 30% of 1RM (2.5 ± 1.06) than 50% total occlusion pressure with 10% of 1RM (5.77 ± 1.46). CONCLUSION: A combination of 70% of total occlusion pressure with 30% 1RM could be beneficial in PwKOA in improving pain, and increasing the quadriceps strength. The changes in the quadriceps strength could be a predictor for knee pain.

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