[New dialysis therapy modalities: what role do they play in the hemodialysis patient's outcome?].

Many studies have been devoted to investigating new techniques and new dialysis strategies aimed at achieving adequate removal of "uremic toxins". Conversely, few studies focus on the effect of different dialysis techniques on long-term outcome, including large series and with adequate follow-up. Dialysis dose, membrane biocompatibility and permeability, convective techniques, and the number and duration of dialysis sessions have all been considered as potentially related to patient outcome. The available data from the literature clearly show a significant relationship between the urea kinetic model based dialysis delivered and long-term patient outcome. A significant positive correlation between survival and Kt/V up to 1.3 per session in patients treated three times a week with standard low flux cellulosic dialyzers has been shown. Many studies have shown an effect of high flux membranes on the appearance of symptoms related to dialysis amyloidosis. It is likely that such an effect is further enhanced by convective or mixed techniques. The role of these techniques in patient survival is suggested by some studies, but should be confirmed in larger series. The use of techniques suitable for ultra-pure dialysis fluids are mandatory whenever high permeability membranes are used. Treatment schedules which include long dialysis sessions or an increased number of sessions such as daily dialysis, seem to be beneficial for the control of hypertension or hyperphosphatemia. However, their role on patient survival has not yet been clearly assessed. Together with the choice of the best strategy, great attention should be paid to other factors known to be related to patient outcome, such as early patient referral, and the type and efficiency of vascular access.