Hemolysis During Membrane Plasma Separation With Pulsed Flow Filtration Enhancement

1994 ◽  
Vol 116 (4) ◽  
pp. 514-520 ◽  
Author(s):  
Jane L. Philp ◽  
Michel Y. Jaffrin ◽  
Luhui Ding
Keyword(s):  
Blood Flow ◽  
Steady Flow ◽  
Hemoglobin Concentration ◽  
Transmembrane Pressure ◽  
Flow Conditions ◽  
Membrane Area ◽  
Shear Rates ◽  
Pulsed Flow ◽  
Plasma Filtration ◽  
Wall Shear

The use of pulsed blood flow in membrane plasmapheresis permits enhancement of plasma filtration yet may result in high levels of hemolysis due to large increases in instantaneous transmembrane pressure (TMP). This work investigates the occurrence of hemolysis as a function of TMP and wall shear rates (γw) for both steady and pulsed blood flow conditions. Two types of hollow fiber filters with identical polypropylene membranes but different lengths and membrane areas (0.1 and 0.25 m2) were tested. Fresh citrated bovine blood was circulated through the fibers at various blood flowrates and TMP in a single pass circuit using a pulsation generator, made of a single roller peristaltic pump. The free hemoglobin concentration of the plasma, Hbm, was measured from permeate samples collected at each set of TMP and γw conditions. It was found that the net hemolysis generated by the filtration was proportional to the membrane area. This justified the introduction of an hemolysis index, IH, equal to the plasma hemoglobin per unit membrane area. The boundary for the occurrence of hemolysis was thus defined by setting IH = 30 mg/ dl.m2. For both steady and pulsed flow conditions the hemolysis boundaries were found to be straight lines in the TMP-γw plane. They were identical for the two filters under steady flow but different for pulsed flow. At the same time mean wall shear rates hemolysis occurred at a lower time mean TMP under pulsed flow conditions than under steady flow conditions.

Shear rate dependent margination of sphere-like, oblate-like and prolate-like micro-particles within blood flow

Soft Matter ◽  
2018 ◽  
Vol 14 (36) ◽  
pp. 7401-7419 ◽  
Author(s):  
Huilin Ye ◽  
Zhiqiang Shen ◽  
Ying Li
Keyword(s):  
Blood Flow ◽  
Shear Rate ◽  
Shape Effect ◽  
Shear Rates ◽  
Micro Particles ◽  
Rate Dependent ◽  
Wall Shear

The shape effect of micro-particles is examined by comparing the margination behaviors of sphere-like, oblate-like and prolate-like micro-particles under different wall shear rates in blood flow.

Unsteady Performance of a Double Entry Turbocharger Turbine With a Comparison to Steady Flow Conditions

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
Colin D. Copeland ◽  
Ricardo Martinez-Botas ◽  
Martin Seiler
Keyword(s):  
Steady Flow ◽  
Flow Behavior ◽  
Turbine Rotor ◽  
Flow Conditions ◽  
Turbine Performance ◽  
Pulsed Flow ◽  
Performance Map ◽  
Engine Operating Condition ◽  
Double Entry ◽  
The Impact

Circumferentially divided, double entry turbocharger turbines are designed with a dividing wall parallel to the machine axis such that each entry feeds a separate 180 deg section of the nozzle circumference prior to entry into the rotor. This allows the exhaust pulses originating from the internal combustion exhaust to be preserved. Since the turbine is fed by two separate unsteady flows, the phase difference between the exhaust pulses entering the turbine rotor will produce a momentary imbalance in the flow conditions around the periphery of the turbine rotor. This research seeks to provide new insight into the impact of unsteadiness on turbine performance. The discrepancy between the pulsed flow behavior and that predicted by a typical steady flow performance map is a central issue considered in this work. In order to assess the performance deficit attributable to unequal admission, the steady flow conditions introduced in one inlet were varied with respect to the other. The results from these tests were then compared with unsteady, in-phase and out-of-phase pulsed flows most representative of the actual engine operating condition.

Unsteady Performance of a Double Entry Turbocharger Turbine With a Comparison to Steady Flow Conditions

2008 ◽  
Author(s):  
Colin D. Copeland ◽  
Ricardo Martinez-Botas ◽  
Martin Seiler
Keyword(s):  
Steady Flow ◽  
Turbine Rotor ◽  
Flow Conditions ◽  
Turbine Performance ◽  
Pulsed Flow ◽  
Performance Map ◽  
Unsteady Performance ◽  
Engine Operating Condition ◽  
Double Entry ◽  
The Impact

Circumferentially divided, double-entry turbocharger turbines are designed with a dividing wall parallel to the machine axis such that each entry feeds a separate 180° section of the nozzle circumference prior to entry into the rotor. This allows the exhaust pulses originating from the internal combustion exhaust to be preserved. Since the turbine is fed by two separate unsteady flows, the phase difference between the exhaust pulses entering the turbine rotor will produce a momentary imbalance in the flow conditions around the periphery of the turbine rotor. This research seeks to provide new insight into the impact of unsteadiness on turbine performance. The discrepancy between the pulsed flow behaviour and that predicted by a typical steady flow performance map is a central issue considered in this work. In order to assess the performance deficit attributable to unequal admission, the steady flow conditions introduced in one inlet were varied with respect to the other. The results from these tests were then compared to unsteady, in-phase and out-of-phase pulsed flow most representative of the actual engine operating condition.

scholarly journals Subsecond calcium dynamics in ADP- and thrombin-stimulated platelets: a continuous-flow approach using indo-1

Blood ◽  
1988 ◽  
Vol 71 (6) ◽  
pp. 1539-1543
Author(s):  
GD Jones ◽  
AR Gear
Keyword(s):  
Blood Flow ◽  
Continuous Flow ◽  
Blood Platelets ◽  
Adenosine Diphosphate ◽  
Cytosolic Calcium ◽  
Human Platelets ◽  
Calcium Dynamics ◽  
Flow Conditions ◽  
Shear Rates ◽  
Flow Apparatus

The regulation and kinetics (less than 5 seconds) of cytosolic calcium changes ([Ca2+]i) in stimulated blood platelets have been investigated under physiological blood flow conditions. Using a newly-developed continuous-flow approach with indo-1-loaded human platelets, adenosine diphosphate (ADP, 10 mumol/L) and thrombin (5 U/mL) were equally effective in significantly increasing [Ca2+]i by 0.5 seconds. ADP induced a transient [Ca2+]i peak of 1 to 2 mumol/L near 2 seconds, whereas thrombin caused a sustained and larger response. The first phase (less than 2 seconds) was not influenced by a lack of extracellular Ca2+, in contrast to the subsequent [Ca2+]i increase that only reached about 0.7 mumol/L for either ADP or thrombin. The shear rates used in our continuous-flow apparatus were physiological (less than 1,258 sec-1) and only slightly increased the basal [Ca2+]i of 0.1 mumol/L. Platelet aggregation (less than 5 seconds), assessed by single- particle counting, was not altered in platelets loaded with indo-1/AM (2.5 mumol/L).

Transition to Turbulence Downstream of a Stenosis for Whole Blood and a Newtonian Analog Under Steady Flow Conditions

2021 ◽  
Author(s):  
Rayanne Pinto Costa ◽  
Blaise Simplice Talla Nwotchouang ◽  
Junyao Yao ◽  
Dipankar Biswas ◽  
David Casey ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Steady Flow ◽  
Whole Blood ◽  
Critical Reynolds Number ◽  
Blood Rheology ◽  
Transition To Turbulence ◽  
Flow Conditions ◽  
Shear Rates ◽  
The Impact

Abstract Blood, a multiphase fluid comprised of plasma, blood cells, and platelets, is known to exhibit a shear-thinning behavior at low shear rates and near-Newtonian behavior at higher shear rates. However, less is known about the impact of its multiphase nature on the transition to turbulence. In this study, we experimentally determined the critical Reynolds number at which the flow began to transition to turbulence downstream of an eccentric stenosis for whole porcine blood and a Newtonian blood analog (water-glycerin mixture). Velocity profiles for both fluids were measured under steady-state flow conditions using an ultrasound Doppler probe placed 12 diameters downstream of an eccentric stenosis. Velocity was recorded at 21 locations along the diameter at 11 different flow rates. Normalized turbulent kinetic energy was used to determine the critical Reynolds number for each fluid. Blood rheology was measured before and after each experiment. Tests were conducted on five samples of each fluid inside a temperature-controlled in-vitro flow system. The viscosity at shear rate 1000 s 1 was used to define the Reynolds number for each fluid. The mean critical Reynolds numbers for blood and water-glycerin were 470 ± 27.5 and 395 ± 10, respectively, indicating a ~19% delay in transition to turbulence for whole blood compared to the Newtonian fluid. This finding is consistent with a previous report for steady flow in a straight pipe, suggesting some aspect of blood rheology may serve to suppress, or at least delay, the onset of turbulence in vivo.

scholarly journals Subsecond calcium dynamics in ADP- and thrombin-stimulated platelets: a continuous-flow approach using indo-1

Blood ◽  
1988 ◽  
Vol 71 (6) ◽  
pp. 1539-1543 ◽  
Author(s):  
GD Jones ◽  
AR Gear
Keyword(s):  
Blood Flow ◽  
Continuous Flow ◽  
Blood Platelets ◽  
Adenosine Diphosphate ◽  
Cytosolic Calcium ◽  
Human Platelets ◽  
Calcium Dynamics ◽  
Flow Conditions ◽  
Shear Rates ◽  
Flow Apparatus

Abstract The regulation and kinetics (less than 5 seconds) of cytosolic calcium changes ([Ca2+]i) in stimulated blood platelets have been investigated under physiological blood flow conditions. Using a newly-developed continuous-flow approach with indo-1-loaded human platelets, adenosine diphosphate (ADP, 10 mumol/L) and thrombin (5 U/mL) were equally effective in significantly increasing [Ca2+]i by 0.5 seconds. ADP induced a transient [Ca2+]i peak of 1 to 2 mumol/L near 2 seconds, whereas thrombin caused a sustained and larger response. The first phase (less than 2 seconds) was not influenced by a lack of extracellular Ca2+, in contrast to the subsequent [Ca2+]i increase that only reached about 0.7 mumol/L for either ADP or thrombin. The shear rates used in our continuous-flow apparatus were physiological (less than 1,258 sec-1) and only slightly increased the basal [Ca2+]i of 0.1 mumol/L. Platelet aggregation (less than 5 seconds), assessed by single- particle counting, was not altered in platelets loaded with indo-1/AM (2.5 mumol/L).

Measurements of Velocity and Wall Shear Stress Inside a PTFE Vascular Graft Model Under Steady Flow Conditions

1997 ◽  
Vol 119 (2) ◽  
pp. 187-194 ◽  
Author(s):  
F. Loth ◽  
S. A. Jones ◽  
D. P. Giddens ◽  
H. S. Bassiouny ◽  
S. Glagov ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Flow Field ◽  
Steady Flow ◽  
Axial Length ◽  
Ptfe Graft ◽  
Flow Conditions ◽  
Data Set ◽  
Stress Region ◽  
Wall Shear

The flow field inside a model of a polytetrafluoroethylene (PTFE) canine artery end-to-side bypass graft was studied under steady flow conditions using laser-Doppler anemometry. The anatomically realistic in vitro model was constructed to incorporate the major geometric features of the in vivo canine anastomosis geometry, most notably a larger graft than host artery diameter. The velocity measurements at Reynolds number 208, based on the host artery diameter, show the flow field to be three dimensional in nature. The wall shear stress distribution, computed from the near-wall velocity gradients, reveals a relatively low wall shear stress region on the wall opposite to the graft near the stagnation point approximately one artery diameter in axial length at the midplane. This low wall shear stress region extends to the sidewalls, suture lines, and along the PTFE graft where its axial length at the midplane is more than two artery diameters. The velocity distribution inside the graft model presented here provides a data set well suited for validation of numerical solutions on a model of this type.

scholarly journals Wall shear rates in human and mouse arteries: Standardization of hemodynamics for in vitro blood flow assays: Communication from the ISTH SSC subcommittee on biorheology

2021 ◽  
Vol 19 (2) ◽  
pp. 588-595
Author(s):  
Mikhail A. Panteleev ◽  
Netanel Korin ◽  
Koen D. Reesink ◽  
David L. Bark ◽  
Judith M. E. M. Cosemans ◽  
...  
Keyword(s):  
Blood Flow ◽  
Shear Rates ◽  
Wall Shear ◽  
Human And Mouse

HN-11500 – a Novel Thromboxane A2 Receptor Antagonist With Antithrombotic Activity in Humans at Arterial Blood Flow Conditions

1994 ◽  
Vol 71 (01) ◽  
pp. 103-109 ◽  
Author(s):  
Helge E Roald ◽  
R Marius Barstad ◽  
Anne Engen ◽  
Peter Kierulf ◽  
Fredrik Skjørten ◽  
...  
Keyword(s):  
Blood Flow ◽  
Receptor Antagonist ◽  
Thromboxane A2 ◽  
Arterial Blood Flow ◽  
Fibrin Deposition ◽  
Flow Conditions ◽  
Thromboxane A2 Receptor ◽  
Shear Rates ◽  
Arterial Blood ◽  
Perfusion Chamber

SummaryIn the present study we have investigated the effect of a 100 mg single oral dose of a newly developed thromboxane A2 receptor antagonist on collagen-induced thrombogenesis in flowing human non-anticoagulated blood. Blood was drawn directly from an antecubital vein over immobilised collagen type III fibrils on a cover slip placed in a parallel-plate perfusion chamber. Shear rates at the collagen surface were characteristic for medium sized (650 s−1) and moderately stenosed (2,600 s−1) arteries. Blood-collagen interactions were morphologically quantified as platelet-collagen adhesion, fibrin deposition and thrombus volume. Activation peptides of coagulation, fibrinopeptide A (FPA), and of platelets, β-thromboglobulin (β-TG), were measured immediately distal to the perfusion chamber.HN-11500 ingestion reduced significantly the thrombus volume by 32% at 2,600 s−1, but not at 650 s−1. However, transmission electron microscopy revealed loosely packed and less degranulated platelets at 650 s−1. The β-TG plasma levels were also reduced at both shear rates by the HN-11500 ingestion. The platelet-collagen adhesion was significantly enhanced at both shear rates. This was apparently a consequence of higher platelet concentrations at the collagen surface, because fewer platelets were consumed by the thrombi after the drug ingestion. In contrast, the coagulation, as measured by fibrin deposition and FPA plasma levels, was not significantly affected by HN-11500.Thus, it appears that the thromboxane A2 receptor antagonist HN-11500 reduces the thrombotic response by primarily impairing the platelet function at arterial blood flow conditions, and particularly at high wall shear rates.

Hemolysis Reduction in Plasmapheresis by Module Design: Operating with Pulsed Flow Filtration Enhancement

1993 ◽  
Vol 16 (2) ◽  
pp. 100-107 ◽  
Author(s):  
J.L. Philp ◽  
M.Y. Jaffrin ◽  
L.H. Ding
Keyword(s):  
Fiber Length ◽  
Unit Length ◽  
Hemoglobin Concentration ◽  
Shear Rates ◽  
Module Design ◽  
Pulsed Flow ◽  
The Mean ◽  
Flow Filtration ◽  
Reduction In Area ◽  
Average Hemoglobin

This study is an investigation into the effects of module design on hemolysis levels during the filtration enhancement of plasmapheresis using pulsed blood flow. Two polypropylene hollow fiber modules (F1 and F2) were compared under steady and pulsed flow conditions. The fiber lengths and membrane areas of the respective filters were 136 mm, 0.1 m2 and 226 mm, 0.25 m2 and were used at wall shear rates of 400 and 600 s-1. Fresh citrated bovine blood was circulated at 90 ml/min through their fibers with permate and retentate being recirculated. Plasma samples were analysed by the Cripps method to obtain the mean free hemoglobin concentration. A comparison of the average hemoglobin released with time per fiber, and per unit length allowed an assessment of the effects of fiber length and shear rate on hemolysis levels. It was concluded that a reduction in area and fiber length would reduce hemolysis levels and design equations are suggested to find the optimum length.

Sign in / Sign up

Export Citation Format

Share Document