[Optimization of extracorporeal dialytic treatment: on-line hemodiafiltration]

The study evaluates the potential of high ultrafiltration on-line hemodialfiltration (HDF) as a means of achieving the goals of extracorporeal RDT: the removal of small and medium-sized molecules, vascular stability and biocompatibility. The removal of small molecules was correlated with the UF rate and therefore with reinfusate volume. Medium-sized molecules were only removed from high permeability synthetic membranes in HD, but to a greater extent in HDF because of higher absorption. Vascular stability during the dialytic session is improved by convective processes, as is confirmed by a low prevalence of arterial hypertension in HDF patients. This suggests that HDF facilitates the achievement of dry body weight and therefore an improved correction of hydrosaline retention which is the main cause of hypertension in RDT patients. The biocompatibility of the dialytic system depends on the membrane and the dialysate. Synthetic membranes were shown to be much less toxic than cellulosic membranes and ultrapure dialysate was a useful aid to reduce the risk of inflammatory stimuli. On-line HDF associated the value of low-cost sterile dialysate-reinfu sate with a highly efficient and well tolerated technique.