Performance Evaluation of Cascade Filtration with High Flow Rate Recirculating Plasma on the Secondary Filter

Cascade filtration (CF) has been performed in 67 on-line procedures in 9 normolipidemic patients with paraproteinemic disorders. A modified dead-end technique has been employed, with high flow rate recirculating plasma on the plasma fractionation filter (QD recycled CF), and an albumin-rich, globulin-poor filtrate was reinfused into the patient. Postprocedure recoveries were 81 ± 15% for albumin, 55 ± 23% for IgM and 48% for cryocrit, with an increase in A/G ratio from 1.8 to 2.1. An improvement was observed also in antiatherogenic/atherogenic lipoproteins ratio, suggesting a possible use of this technique in the treatment of familial hypercholesterolemia. Plasma primary separation was obtained by centrifugation or by filtration, and no significant differences were observed on subsequent protein fractionation process. An albumin priming of the plasmafractionation circuit accounted for an additional 13% saving in postprocedure level. Different surface area secondary filters have been employed: with larger surfaces, larger volumes were processed without any increase in the waste volume and with reduced need for washouts, but with an additional loss of small molecules possibly due to entrapping onto the membrane.

Rheohaemapheresis of ophthalmological diseases and diseases of the microcirculation

Blood rheology was considered to be of limited clinical importance, until extracorporeal technologies enabling the treatment of cellular and plasmatic hyperviscosity syndromes were introduced. However, a wide range of applications, mainly referring to rheologically determined diseases of the microcirculation exists but has so far hardly been taken into consideration. The extension of indications was due to modern technical developments leading to different approaches of secondary separation such as precipitation, ad- or absorption and filtration. Based on 18 years of experience with different separation technologies the combination of some centrifugal devices applied for cell--plasma separation with secondary filtration (Rheohemapheresis) appears to be the most efficacious and economical approach for such extracorporeal treatments. The sequence and frequency of rheohaemapheresis treatments depends on the measurement of rheological measurements in combination with clinical--chemical data which are related to the distribution kinetics and synthesis rate of both blood cells and plasma proteins. Standardised treatment protocols proved the efficacy of initial therapies and were applied for controlled trials whereas long term therapies may need more flexible treatment approaches. So far an increasing experience exists for the treatment of ophthalmologic diseases, otologic disorders, diabetic complications and cardiological diseases. Rheohemapheresis was shown to be a safe treatment approach, if a careful risk assessment prior to the initiation of the therapies is performed. The treatment cannot cure diseases but enables a substantial improvement of the quality of life in patients without treatment alternatives.

Rheotherapy for Vascular Disorders

Patients with vascular disorders are seldom offered apheresis in the management of their symptoms.

In this article we review the different apheretical techniques used in these situations.

Plasma Exchange--Associated Immunoglobulin M--Negative Hantavirus Disease after a Camping Holiday in Southern France

A 37-year-old Belgian patient presented with acute nephropathia epidemica (NE) shortly after a camping holiday in southern France. Unusual symptoms were initial noncardiogenic lung involvement, followed by severe acute renal failure, acute acalculous cholecystitis, presence of immunoblasts in the bone marrow, and hemolytic anemia, presenting as hemolytic uremic syndrome. Positive immunoglobulin (Ig) A and rising IgG titers against Puumala hantavirus (PUUV) were detected, but IgM remained negative on days 8 and 20. The results of reverse-transcriptase-polymerase chain reaction performed on day 8 were positive for PUUV. This is the first report of an iatrogenically IgM-negative hantavirus case due to the selective removal of heavy-weight molecules during plasma exchange via the centrifugation technique. This is also the first report of proven NE from the Mediterranean part of France.

Apheresis for Renal Disease

Many primary renal diseases are associated with either antibody deposition within the glomerulus or an antibody associated autoimmunity, as may be seen with certain vasculitidies. Examples of these diseases include Goodpasture's syndrome, cryoglobulinemia, antineutrophil cytoplasmic antibody positive syndromes, and other forms of rapidly progressive glomerulonephritis. Immunoglobulins also may be nephrotoxic to the tubules such as is the case with myeloma related light chains. Given the rapid removal of immunoglobulins by therapeutic plasma exchange, this modality has been considered an appealing management option in the treatment of these renal diseases. Although not classically considered as autoimmune diseases, thrombotic thrombocytopenic purpura and hemolytic uremic syndrome are related syndromes which often involve the kidneys. Although previously unexplained, it has been long appreciated that therapeutic plasma exchange (PE) can be a useful treatment for these microangiopathic hemolytic anemias, but the most recent insights into their pathogenesis suggest that PE may be beneficial by replacing a missing enzyme or removing pathogenic autoantibodies.

Hyperviscosity syndrome

Hyperviscosity syndrome is clinically manifested by oronasal bleeding, retinal hemorrhages, and variable neurological symptoms. It occurs when resistance to flow of blood increases sharply, resulting in impaired transit through the microcirculatory system. The most common cause of hyperviscosity is increased concentrations of gamma globulins, either monoclonal in malignant disease or polyclonal, usually seen with rheumatic disorders. Increased numbers of red blood cells, as in polycythemia vera, can result in viscous blood. Extreme increases in concentrations of mature and immature white blood cells can also produce hyperviscosity. Treatment with plasma exchange is required when the clinical syndrome is symptomatic. Although plasma exchange is not a completely benign procedure, it represents the most effective method of controlling hyperviscosity.

Preliminary study on the effect of substrate size on cellular immunomodulations

It is well known that the adsorption behavior of lymphocytes on fiber materials is related to the fiber size. In our previous study, murine lymphocytes cultured on various sizes of fibers showed different interleukin 2 (IL-2) activity, and ultrafine fibers of 1.5 microns showed the highest value. Based upon those results and to further evaluate the effects of fibers of different sizes on the modulation of lymphocyte functions, Concanavalin A (Con A) was immobilized on the surface of fibers having different diameters, and murine lymphocytes were cultured on these fibers. Fiber size effects on the lymphocytes were evaluated in terms of IL-2 production and adhesion morphology. The Con A immobilized fibers could stimulate lymphocytes to levels as high as 70-80% of the maximal value induced by the Con A solution. Statistical differences in IL-2 production were not observed among the fiber sizes although as fibers decreased in size, the contact area of the lymphocytes with fibers became smaller. The results suggest that smaller diameter fibers with less contact to adherent lymphocytes can affect lymphocyte function to similar extents on larger diameter fibers and that ultrafine fibers might be useful substrates for immobilizing immunomodulators.

Cascade filtration with reverse rinse of the secondary filter

With cascade filtration (CF) secondary filter plugging may render some procedures difficult, particularly with cryoglobulinemia or macroglobulinemia patients, when filters are subjected to the most consistent burden. To prevent plugging, in the initial management of seven patients with cryoglobulinemia or macroglobulinemia we employed polymethylmethacrylate secondary filters produced by Toray Industries Inc., Tokyo, with pores calculated at 0.1 micron (QS-12-70). In the subsequent sessions, when circulating macroproteins were reduced to more acceptable levels, secondary filters with pores of 0.06 micron were used (QS-12-50). The filtration efficiency of both filters was maintained throughout the procedures with reverse rinses carried out when the transmembrane pressure from the values of 80-130 mm Hg reached the values of 250 mm Hg. With this improved technique, 2.6-3.31 liters of plasma could be treated, producing adequate clinical benefits. From a laboratory point of view, the differential sieving for albumin and macroglobulins was 61% for the QS-12-50 filters and 56% for the QS-12-70 models.