Pressure-flow relations of human blood in hollow fibers at low flow rates

Suspensions of human red cells in citrated plasma, in Ringer solution, and in Ringer solution containing albumin were passed through straight and curved glass and plastic hollow fibers (diameter range, 100–1,000 μ). Pressure-flow relations were measured over the pressure range of 0.1– 800 mm water, corresponding to a shear stress range of 0.01– 80 dynes/cm2. The suspensions were tested simultaneously in a rotational viscometer. It was found that red cell suspensions exhibit a yield shear stress only if the plasma protein fibrinogen is present. Experimental pressure-flow data in hollow fibers were in excellent agreement with rotational viscometer measurements and with analytical predictions based on the assumptions that blood flows as a homogeneous continuum and that the velocity at the wall is zero. Effects of tube surface characteristics and curvature on the pressure drop-flow rate relation were not discernible. microcirculation models; model blood flow; yield stress of blood; capillary blood flow and viscometry; fibrinogen and blood flow in hollow fibers; non-Newtonian flow of blood in hollow fibers Submitted on July 20, 1964