Influence of vessel diameter on red cell distribution at microvascular bifurcations.

The uneven distribution of red blood cells (RBCs) to daughter branches at microvascular bifurcations, often referred to as "plasma skimming," has been characterized in previous studies by comparisons of flux-flow plots of red cell flow fraction (F*) versus volumetric flow fraction (Q*) at single junctions. Comparisons of flux-flow plots for single bifurcations with differing daughter/parent vessel diameter ratios (Dd/Dp = 1.0 vs 0.5) have been made to reveal the influence of vessel size on red cell distribution at vessel junctions of four different geometries (100 x 100, 50 x 50, 100 x 50, 50 x 25 microns). Experimental data determined by effluent collection were compared to those from video fluorescence microscopy experiments, as well as to numerical computations from theoretical models. Statistical comparisons using a likelihood ratio test indicate that vessel diameter ratio, Dd/Dp, has no detectable influence on RBC distribution in these microvascular bifurcations.