Laser diffraction ellipsometry of erythrocytes under controlled shear stress using a rotational viscosimeter

An ektacytometric extension for the Contraves LS-30 viscosimeter is described, as well as the procedure to measure erythrocyte deformability and rouleau formation with this combination. The method error (coefficient of variation) for the measurements of the erythrocyte elongation index appeared to be less than 1%, while both intra- and interindividual variation were around 2%. Preliminary clinical experiments performed on blood from different patient groups (i.e., diabetes, uraemia, sickle cell anaemia) clearly demonstrated more rigid erythrocytes than normal. It can be concluded that it is possible now to analyse with 1 instrument: plasma viscosity, whole blood viscosity at shear rates from 0.01 to 236 s-1, erythrocyte deformability and rouleau formation.