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 μm (QS‐12‐70). In the subsequent sessions, when circulating macroproteins were reduced to more acceptable levels, secondary filters with pores of 0.06 μm 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.