Apheresis ProcedureBesides dialysis, apheresis takes an important therapeutical place as an extracorporeal blood purification treatment. Basically, a distinction is made between whole blood processes (such as haemoperfusion) and filtration procedures. In filtration procedures blood plasma is separated via a hollow-fiber capillary as a first step. If this plasma is then dispose of and replaced by donated fresh frozen plasma (FFP) or a solution of human serum albumin, the process is called a therapeutic plasma exchange (TPA or Pex). This exchange is not selective, as non-pathologic substances (e.g. coagulation factors) in the plasma are eliminated. Still, this is presently the gold standard for numerous indications. If the pathogens can be characterized more precisely, more selective procedures are frequently used. They include LDL apheresis and immune apheresis. Elevated LDL-cholesterol and lipoprotein (a) (Lp (a)) levels in the blood are generally recognized as some of the essential risk factors for diseases of the cardiovascular system. In some patients who suffer from the so-called familial hypercholesterolemia procedures using medication usually fail. In such cases therapeutic apheresis is a very efficient alternative that is tolerated well. In cascade filtration (double filtration, lipid filtration) the blood plasma that was separated during the first step is purified through a second filter to remove macromolecular substances such as LDL-choloesterol and Lp(a). The plasma is then returned to the patient’s blood circulation. This has a positive effect on the rheological properties (flow properties) of the blood and thus the circulation in smallest blood vessels. A small number of the population suffer from diseases that are a result of malfunctioning of the immune system. Endogenous substances are wrongly considered to be foreign, so-called antigens, and therefore attacked. The immune reaction is caused by the activation of B and T cells in the blood. This leads to an increased production of antibodies, immunoglobulins. The therapy of such diseases includes either a removal of excess antibodies or activated cells from the blood (immune adsorption and cytapheresis). In both cases this will lead to an alleviation of symptoms. The Immuloc® filter made by the company 3M is used to remove activated leukocytes selectively from blood circulation. They are caught in the special surface of the fiber bundle in the filter. It is not necessary to separate the plasma first. Ulcerative colitis and Crohn’s disease are some of the indications for this procedure. This therapy has also been applied with great success for skin diseases such as pyoderma gangrenosum.