Erythrocyte filtrability measurement by the initial flow rate method

A new filtration technique, based on the initial filtration rate of a diluted RBC suspension through 5 mu Nucleopore filter is described. As only a few hundreds RBCs traverse each pore and as the measurement are made in a few seconds, the method is by large insensitive to filter plugging and to sedimentation effects. The results are given as a filtration index IF which is, as a first order approximation, independent of the filter conductance and of the suspending medium viscosity. The filtration times are measured electronically. The filters are re-used many times. The influence on the results reproducibility of RBC washing, of the anticoagulant, of the blood sample and the suspension storage times are considered. With our technical procedure, the relative incertitude on the measurement of I.F. is about +/- 10%. The filtration index is shown to be an intrinsic RBC filterability property.