Plasma skimming in serial microvascular bifurcations.

Red cell distribution in simple two bifurcation networks has been studied experimentally. The results indicate that fractional red cell flux/fractional volumetric flow curves can be asymmetric at the downstream bifurcation. The important parameters affecting this asymmetry are the fractional flow into the upstream branch Q1*, and the ratio of the distance between junctions to the volumetric flow rate, z/Q. The asymmetry is attenuated as z/Q increases. In 50-micron tubes with Q1* of 0.5, symmetric phase separation behavior is regained when z/Q is greater than 200 sec/mm2. In 25-micron tubes symmetry is recovered before z/Q reaches the value of 50 sec/mm2. These results agree with in vivo data of previous studies and provide additional evidence that flow history can be important in microvascular networks if junctions are close together or flow rates are sufficiently high.