Plasma filtration is based on separation according to the size or mass of the particles and molecules in the blood plasma.
The plasma is filtered through a plastic membrane with a defined pore size (see figure).
First, blood is separated into blood cells and plasma in a cell separator (step 1).
Then the plasma is pressed through the pores of the filter (step 2)
Unfilterable components of the plasma with a certain size are retained similar to a coffee filter.
Retained or eliminated as in all filtration processes (e.g. "lipid filter" and "rheofilter"): VLDL, IDL, LDL and Lp(a) particles, fibrinogen and other coagulation factors, immunoglobulins and other larger molecules (e.g. α 2-macroglobulin).
As a result, plasma filtration is inevitably always lipoprotein elimination and rheotherapy at the same time
Before starting lipoprotein adsorption continuous treatment, filtration can be used to remove VLDL, IDL, LDL or Lp(a) temporarily (about 6 - 12 months). Specific LDL apheresis and selective LDL elimination lower LDL and Lp(a) much more effectively.
Plasma filtration improves the flow properties of plasma and reduces erythrocyte aggregation (see glossary). This simultaneously improves the flow properties of the blood, which has a favourable effect on disturbances of the microcirculation (blood flow in the smallest vessels). In this sense, filtration is used specifically as rheotherapy, whereby organs (eyes, inner ear, brain, skin, etc.) are supplied with blood more intensively.
If the erythrocyte count is too high, additional red blood cells may be removed after filtration treatment to improve the flow properties (rheohaemotherapy). This treatment, which was further developed at the DHZ, represents a new principle, rheohaemotherapy.
The plasma filter was used for the first time in Japan and subsequently introduced into clinical routine at the University Hospital in Cologne.