DOUBLE-PASS DIALYSIS - A NEW METHOD OF RENAL REPLACEMENT IN PATIENTS WITH MALFUNCTIONING VASCULAR ACCESS

Several patients undergoing chronic renal replacement therapy present problems related to their vascular access. Low blood flows and high ra tes of recirculation are common in such patients in which, for this re ason, it becomes difficult to apply highly efficient techniques or tec hniques where diffusion and convection are combined as in hemodiafiltr ation. In these patients we studied the possibility of partially recir culating the blood in the extracorporeal circuit in order to increase the flow rate per single hollow fiber; we defined our system ''double pass dialysis''. We evaluated the system's efficiency in 12 patients d uring 24 dialysis sessions: 12 high flux dialysis sessions (without re infusion) and 12 hemodiafiltration sessions (9 liters reinfusion). Dif ferent surfaces of polyacrylonitrile dialyzers were utilized (1.3-1.7- 2.1 sqm) at 250 and 350 ml/min of blood flow with or without 100 ml/mi n of recirculation. During each dialysis session blood and dialysate s amples were taken in order to calculate BUN, Creatinine, Phosphate and Inuline clearances from both the blood and dialysate side. The cleara nces of low molecular weight solutes were not really influenced by the artificial increase of the blood flow, but on the other hand, the cle arances of higher molecular weight solutes increased from 10 to 30% du ring both high flux dialysis and hemodiafiltration with recirculation. This increase was evident mostly in hemodiafiltration suggesting that the cleaning effect on the membrane has a positive impact on the perm eability. The good clinical results obtained with the double pass dial ysis show that the system is safe and reliable and may become a valid support in critical situations in order to reach adequate dialysis tre atment.