Clinical Benefits of Predilution On-Line Hemodiafiltration

Abstract

There are two types of hemodiafiltration (HDF) treatments, predilution and postdilution. In Japan, clinical doctors have been using the on-line HDF treatment for renal replacement therapy for 20 years. However, this treatment is not popular in Japan because it has not been recognized by the government. Generally, the advantage of postdilution HDF over predilution HDF resides in the fact that it removes low-weight molecular proteins (LWMPs) and protein-binding uremic toxin. Thus, postdilution on-line HDF has been widely used in the world, but in Japan predilution on line-HDF has been the preferred treatment. There are several reasons why predilution on-line HDF has been the preferred treatment in Japan. Predilution on-line HDF is superior to postdilution on-line HDF in removing LWMPs and protein-binding uremic toxin, for example p-cresol and homocysteine. In addition, there are several reports on the biocompatibilities in predilution on-line HDF. Predilution on-line HDF is associated with reduced shear stress, and the synthesis of cytokine and cellular adhesion molecules. Moreover, with predilution on-line HDF/hemofiltration, blood pressure remains stable during treatment. In Japan, over 90% of dialysis patients have been receiving hemodialysis (HD) therapy with the ultra-high flux dialysis membrane. These ultra-high flux dialysis membranes achieve β₂-microglobulin clearance rates of >50 ml/min. In addition, these membranes have the same power as postdilution HDF because they allow automatic internal filtration. Thus, in spite of HD treatment, as a result, the effect is the same as with postdilution HDF treatment. There have been small and retrospective studies on predilution on-line HDF, and we must use a hemodiafilter during the on-line HDF treatment. However, the hemodiafilter has been unsuccessful in reaching the LWMP removal rates which we demand. And the most important point is to carry out a prospective multicenter randomized controlled trial of predilution on-line HDF in the near future.