In vitro Evaluation of Solute Removal Characteristics in Intermittent Infusion Hemodiafiltration.

Background: In a typical hemodialysis (HD) session, excessive water removal sometimes induces peripheral circulatory failure and a rapid drop in blood pressure. Intermittent infusion hemodiafiltration (I-HDF), a new modality of dialysis therapy, has been developed to improve peripheral circulation by repeated intermittent infusion of dialysate during an HD session. In a typical I-HDF session, we infuse a volume of 200 mL of ultrapure dialysate by backfiltration at 150 mL/min every 30 min. The same volume is alternately removed from the patient's blood by filtration at a constant rate after each infusion. However, solute removal characteristics in I-HDF have not been clarified previously. We therefore conducted an in vitro study to investigate the characteristics of solute removal and the factors affecting such removal. Summary: We used human plasma to evaluate the effects of filtration (QF)/infusion (QI) flow rates on solute clearance (CL) and to estimate the time-averaged solute CL (TACL) values. The CL values for all solutes decreased with increasing QI. For small molecules such as urea, the CL values predominantly decreased with increasing QI because of decreasing diffusive transport. For medium and large solutes such as beta 2 microglobulin or larger, CL values predominantly increased with increasing QF because of increasing convective transport. However, the effects of these changes on TACL values were small compared with the CL value in a typical HD session because of the alternate filtration and infusion in I-HDF. Key Messages: Solute removal characteristics in I-HDF do not differ significantly from those in conventional HD treatment.