Advancing Postdilution Hemodiafiltration for Global Sustainability: A Japanese Blueprint

Japan leads globally in HDF adoption, with online predilution HDF used in the majority of HDF treatments. Although associated with excellent outcomes, predilution HDF requires large substitution volumes and high dialysate production, raising sustainability concerns.

This study employed a narrative review integrating expert consensus, Japanese registry data (JSDT), dialysis system specifications, and comparative clinical and kinetic literature to contrast predilution and postdilution strategies and derive an implementation pathway.

Postdilution HDF provides higher convective efficiency and solute removal per liter of fluid than predilution HDF, enabling comparable performance with lower total fluid requirements when prescriptions are optimized. A stepwise transition strategy is proposed: (1) progressive blood flow optimization; (2) selection of HDF-appropriate dialyzers with strict albumin permeability control; (3) anticoagulation optimization for higher filtration fractions; (4) gradual introduction and escalation of postdilution convection with automated fluid control; (5) dialysate-to-blood flow alignment allowing reduction of total dialysate flow while preserving clearance; and (6) iterative monitoring of efficacy and tolerance using clinical targets and biomarker response.

A pragmatic transition toward optimized postdilution HDF can preserve Japan's high-quality dialysis care while improving resource efficiency. Registry-based evaluations and targeted randomized studies are needed to confirm clinical outcomes and quantify economic and environmental benefits.