Filtration pressure and red blood cell deformability: evaluation of a new device: erythrometre.

The authors have tested a new device that records the filtration pressure of a suspension of red blood cells (R.B.C.) passing through a 3 micron pore diameter filter. As the flow rate is constant, the pressure increase allows to appreciate an index of the R.B.C. deformability. In order to test the performances of this new equipment, the authors have studied the influence of the variation of the following parameters. Haematocrit from 0.5 to 2%, Buffer composition; time elapsing from drawing to measurement: from hour 0 to hour 3. This analysis has been performed on donors; on packed red cells preserved in CPD, from D0 to D21 and on patients specimens and the results have been compared to the whole blood filtration according to the Reid and Dormandy method. The following parameters were simultaniously measured: Whole blood viscosity by means of a Low Shear 30 viscosimeter, Intraerythrocyte ATP by bioluminescence, Membrane lipid composition (cholesterol, phospholipids), Scanning electron microscopy. This new apparatus, measuring the filtration pressure seems to be a more sensitive and reproductible method allowing to approach the RBC deformability, and quite usefull in clinical haemorheology.