Abstract
New synthetic membranes have been developed to reduce the ultrafiltration coefficient (Kf) maintaining an adequate permeability to medium-large solutes and a good bio-compatibility. The new Fresenius F6 Low Flux Polysulphon Membrane is studied in this paper as far as hydraulic and permeability properties are concerned. For this purpose in vitro and in vivo tests have been carried out in a series of different conditions.
In vitro sieving coefficients were near 1 for solutes with molecular weight up to 5000 Daltons. The ultrafiltration coefficient of the device was 5.4 ml/h/mmHg while the value of Kf normalized per square meter was lower than 5 ml/h/mmHg. The geometry of the blood path was adequate even operating at high blood flows without excessive resistance and obligate filtration. This resulted in vivo in a good performance during short dialysis schedules with good clearances of small and large molecules and with no risks of backfiltration. In fact, the low permeability to water permits constant operation with positive transmembrane pressures without excessive ultrafiltration rates. The biocompatibility of the membrane was excellent and high capacity of adsorption for beta-2 microglobulin was demonstrated.
These results suggest that these membranes seem to be able to join the advantages of the traditional cellulosic membranes and of the newer synthetic membranes reducing their relative disadvantages. (Int J Artif Organs, 1989; 12:450-60)
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