Continuous monitoring of erythrocyte sedimentation process: a new possible mechanism of erythrocyte sedimentation.

An automated system is constructed to record the complete course of erythrocyte sedimentation process. In this system a light source and a paired photodetector are employed to monitor the change of light transmittance at the junction of plasma and the sedimenting red blood cell column, thus providing a continuous record of erythrocyte sedimentation as a function of time. Differentiation of this sedimentation--time curve yields a velocity--time curve of erythrocyte sedimentation. Frequently recorded "spikes" on top of the velocity--time curve imply the episodes of very rapid fall of erythrocytes in the sedimentation tube that cannot be explained by the currently accepted theory of erythrocyte sedimentation based mainly on Stokes' law, and a new mechanism of rouleau coalescing and fracturing is proposed to account for them.