Abstract
The operation of recirculating single pass (RSP) for dialysate supply has been devised to reduce the dialysate side film resistance and to increase the effective membrane area for solute and water transfer. Clinical, experimental and theoretical considerationss with respect to the RSP performance were done with use of newly devised parameter (R), which was defined as the ratio of the total amount of solute removal in RSP to that in single pass (SP). A relationship between mass transfer-area coefficient (KA) and recirculating dialysate flow rate (QD) for six different dialyzers was examined in vitro. The greatest change of KA with QD was observed for Kuraray KF-11, so that this dialyzer would be more suitable for RSP treatment. From this result, the total amount of solute removal ratio (R) for various treatments could be predicted by the compartment model. Recirculating single pass (RSP) technique was found to be effective for relatively larger molecular substances in hemodialysis. The optimum flow rate of recirculating dialysate existed in RSP treatment for each substance. However, the hemodiafiltration (HDF) involves bulk flow through the membrane, so that R decreases as the ultrafiltration rate (QF) increases. For the substances existing in dialysate like Na+, the solute transfer rate from dialysate to blood in RSP was higher than that in SP.
