Near-wall excess of platelets induced by lateral migration of erythrocytes in flowing blood

Abstract

In this study we present experimental data on the inhomogeneous distribution of platelets in polyethylene tubes (200 microns diam) based on the inverse Fåhraeus effect for platelets. It is shown that platelets are expelled toward the red blood cell-depleted marginal layer near the tube wall by mutual interaction with erythrocytes. By means of a straightforward model, the near-wall concentration of platelets could be estimated from measurements on the average tubular platelet concentration. The marginal layer originates from the hydrodynamic interaction of the deformable erythrocytes with the tube wall. If the tube diameter is large compared with the size of the erythrocytes, the lateral migration effects can effectively be scaled on the absolute distance between the erythrocytes and the tube wall. This results in the main conclusion that the near-wall concentration of platelets is significantly enhanced up to about seven times the average concentration, practically irrespective of the tube diameter in the range of 100-500 microns. Where comparable, the results of this study are in accordance with experimental data of other authors.

Particle trapping by an external body force in the limit of large Peclet number: applications to magnetic targeting in the blood flow

“…In addition we have not modelled the effects of lift on the red blood cells away from the vessel wall. This creates a RBC-depleted marginal layer lying at the edge of a vessel (typical width 2-4 μm [17]) in which shear-induced diffusion is (presumably) reduced and which will also lead to an additional outwardly directed radial force on the targeted particles in opposition to the lift on RBCs away from the vessel wall (this force is observed on platelets and other small blood borne particles [26]). Furthermore, we have omitted from our discussion the effect of the vessel wall on the particle motion which becomes significant when the particle is a distance of the order of its radius from the vessel wall; these are treated in considerable detail for a spherical particle in [10].…”

In vivo whole-field blood velocity measurement techniques

“…This effect also indicates that the erythrocytes do not follow exactly the motion of the blood plasma, which implies that they may not always be suitable as ''natural'' tracer particles for blood flow measurements. Uijttewaal et al (1993Uijttewaal et al ( , 1994 showed that platelets experience a reversed Fåhraeus-Lindquist effect and concentrate in the erythrocyte-depleted layer. Plasma consists mainly of water.…”

Should We Reconsider Recommendations for Red Blood Cell Transfusion?

“…28 Under normal circumstances, red cell flow is maximal at the center of a vessel, tending to push platelets towards the periphery of the vessel lumen, thereby optimizing their interaction with injured endothelium and promoting hemostasis. 29,30 At present the optimal hematocrit/hemoglobin concentration to avoid/treat a hemostatic disorder remains unknown. Limited experimental evidence suggests that hematocrits higher than those required to provide a normal oxygen delivery, and possibly as high as 35%, may be required to sustain hemostasis in bleeding patients.…”