The Effects of External Compression on Venous Blood Flow and Tissue Deformation in the Lower Leg

1999 ◽  
Vol 121 (6) ◽  
pp. 557-564 ◽  
Author(s):  
Guohao Dai ◽  
J. P. Gertler ◽  
R. D. Kamm
Keyword(s):  
Blood Flow ◽  
Venous Pressure ◽  
Venous Blood ◽  
Shear Stresses ◽  
Venous Blood Flow ◽  
Element Analysis ◽  
Uniform Compression ◽  
External Compression ◽  
Typical Application ◽  
Flow Velocities

External pneumatic compression of the lower legs is effective as prophylaxis against deep vein thrombosis. In a typical application, inflatable cuffs are wrapped around the patient’s legs and periodically inflated to prevent stasis, accelerate venous blood flow, and enhance fibrinolysis. The purpose of this study was to examine the stress distribution within the tissues, and the corresponding venous blood flow and intravascular shear stress with different external compression modalities. A two-dimensional finite element analysis (FEA) was used to determine venous collapse as a function of internal (venous) pressure and the magnitude and spatial distribution of external (surface) pressure. Using the one-dimensional equations governing flow in a collapsible tube and the relations for venous collapse from the FEA, blood flow resulting from external compression was simulated. Tests were conducted to compare circumferentially symmetric (C) and asymmetric (A) compression and to examine distributions of pressure along the limb. Results show that A compression produces greater vessel collapse and generates larger blood flow velocities and shear stresses than C compression. The differences between axially uniform and graded-sequential compression are less marked than previously found, with uniform compression providing slightly greater peak flow velocities and shear stresses. The major advantage of graded-sequential compression is found at midcalf. Strains at the lumenal border are approximately 20 percent at an external pressure of 50 mmHg (6650 Pa) with all compression modalities.

Splenic baroreceptors control splenic afferent nerve activity

2006 ◽  
Vol 290 (2) ◽  
pp. R352-R356 ◽  
Author(s):  
Karli Moncrief ◽  
Susan Kaufman
Keyword(s):  
Blood Flow ◽  
Venous Pressure ◽  
Venous Blood ◽  
Splenic Vein ◽  
Afferent Nerve ◽  
Arterial Blood Flow ◽  
Venous Blood Flow ◽  
Nerve Activity ◽  
Vein Occlusion ◽  
Arterial Blood

Stenosis of either the portal or splenic vein increases splenic afferent nerve activity (SANA), which, through the splenorenal reflex, reduces renal blood flow. Because these maneuvers not only raise splenic venous pressure but also reduce splenic venous outflow, the question remained as to whether it is increased intrasplenic postcapillary pressure and/or reduced intrasplenic blood flow, which stimulates SANA. In anesthetized rats, we measured the changes in SANA in response to partial occlusion of either the splenic artery or vein. Splenic venous and arterial pressures and flows were simultaneously monitored. Splenic vein occlusion increased splenic venous pressure (9.5 ± 0.5 to 22.9 ± 0.8 mmHg, n = 6), reduced splenic arterial blood flow (1.7 ± 0.1 to 0.9 ± 0.1 ml/min, n = 6) and splenic venous blood flow (1.3 ± 0.1 to 0.6 ± 0.1 ml/min, n = 6), and increased SANA (1.7 ± 0.4 to 2.2 ± 0.5 spikes/s, n = 6). During splenic artery occlusion, we matched the reduction in either splenic arterial blood flow (1.7 ± 0.1 to 0.7 ± 0.05, n = 6) or splenic venous blood flow (1.2 ± 0.1 to 0.5 ± 0.04, n = 5) with that seen during splenic vein occlusion. In neither case was there any change in either splenic venous pressure (−0.4 ± 0.9 mmHg, n = 6 and +0.1 ± 0.3 mmHg, n = 5) or SANA (−0.11 ± 0.15 spikes/s, n = 6 and −0.05 ± 0.08 spikes/s, n = 5), respectively. Furthermore, there was a linear relationship between SANA and splenic venous pressure ( r = 0.619, P = 0.008, n = 17). There was no such relationship with splenic venous ( r = 0.371, P = 0.236, n = 12) or arterial ( r = 0.275, P = 0.413, n = 11) blood flow. We conclude that it is splenic venous pressure, not flow, which stimulates splenic afferent nerve activity and activates the splenorenal reflex in portal and splenic venous hypertension.

Fetal pulmonary venous blood flow velocities in a normal population and new calculated reference values

2016 ◽  
Vol 36 (11) ◽  
pp. 1033-1040 ◽  
Author(s):  
Franz Bahlmann ◽  
Ralph Gallinat ◽  
Monica Schmidt-Fittschen ◽  
Ammar Al Naimi ◽  
Iris Reinhard ◽  
...  
Keyword(s):  
Blood Flow ◽  
Reference Values ◽  
Normal Population ◽  
Venous Blood ◽  
Venous Blood Flow ◽  
Blood Flow Velocities ◽  
Flow Velocities

scholarly journals Assessment of blood flow velocities and venous pressures using a dual-sensor guidewire in symptomatic dural sinus stenoses

2019 ◽  
Vol 130 (6) ◽  
pp. 1992-1996 ◽  
Author(s):  
Stéphanie Lenck ◽  
Fabrice Vallée ◽  
Vittorio Civelli ◽  
Jean-Pierre Saint-Maurice ◽  
Patrick Nicholson ◽  
...  
Keyword(s):  
Blood Flow ◽  
Intracranial Hypertension ◽  
Idiopathic Intracranial Hypertension ◽  
Venous Pressure ◽  
Venous Blood Flow ◽  
Lateral Sinus ◽  
Pulsatile Tinnitus ◽  
Dual Sensor ◽  
Blood Flow Velocities ◽  
Flow Velocities

Lateral venous sinus stenoses have been associated with idiopathic intracranial hypertension and venous pulsatile tinnitus. Venous pressure measurement is traditionally performed to assess the indications for stenting in patients with idiopathic intracranial hypertension. However, its reliability has recently been questioned by many authors. The dual-sensor guidewire was first developed for advanced physiological assessment of fractional and coronary flow reserves in coronary artery stenoses. It allows measurement of both venous pressure and blood flow velocities. The authors used this device in 14 consecutively treated patients to explore for symptomatic lateral sinus stenosis. They found that venous blood flow was significantly accelerated inside the stenotic lesion. This acceleration, as well as the pulsatile tinnitus, resolved in all patients following stent placement. According to the authors’ results, this guidewire can be helpful for establishing an indication for stenting in patients with pulsatile tinnitus and idiopathic intracranial hypertension.

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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