Filtrability of whole blood and erythrocyte suspensions under the influence of several anticoagulants.

: Red cell deformability was frequently estimated by filtration tests. Filtrability tests with whole blood samples reveal striking differences in flow rate depending on the anticoagulant used. To clarify the reasons for this filtrability of whole blood samples and of red cell suspensions with similar packed cell volume were compared under the influence of EDTA-Na2 1.5 mg/ml, heparin 75 U/ml, and citrate Na 0.38% (w/v). Furthermore, after use in whole blood filtration test filters were examined by scanning electron microscopy (SEM). Filtration tests with red cell suspensions in presence of the different anticoagulants revealed no significant differences. This suggests that the differences in filtrability of differently anticoagulated whole blood samples are not reflecting differences in red cell deformability but different reactivity of the coagulation or the platelet system. SEM examination of filters after filtration tests with heparinised whole blood samples showed large platelet adhesions covering the filters and blocking the filter pores to a great extent. Since this is not found in case of EDTA-anticoagulated samples this anticoagulation is recommended for filtration tests of whole blood samples, if red cell deformability cannot be examined with platelet-free red cell suspensions.