High-flux dilaysers may result in filtration from dialysate to blood in the efferent part of the dialyser due to a reverse transmembrane pressure gradient: this effect is called Backfiltration
PDF and HDF flow rates were individualized according to the patient´s tolerance, in the range of 200 to 300 mL/min, UF rate was set at 300 to 350 mL/hour to maintain an obligatory transmembrane pressure gradient to attenuate backfiltration of HDF into PDF