Benefit of low-convection-volume post-dilution online hemodiafiltration from the viewpoint of green nephrology: a retrospective study

Abstract Background Environmental changes, such as global warming and abnormal climate changes, have become a major global issue. In this study, we focused on reducing the total dialysate flow rate ( Q D_total ) during online hemodiafiltration as an immediately implementable and feasible countermeasure. Accordingly, this study was aimed at investigating the impact of post-dilution online HDF (post-HDF) at Q D_total = 350 mL/min on the solute removal performance and at considering treatment conditions that would minimize excessive albumin leakage when using high-performance membrane hemodiafilters. Methods On the basis of data on the treatment conditions and solute removal characteristics obtained when patients were switched from predilution online HDF (pre-HDF) at Q D_total = 500 mL/min to post-dilution online HDF (post-HDF) at Q D_total = 400 mL/min, the authors examined the appropriate substitution fluid volume to be used. The solute removal performances of post-HDF at Q D_total values of 400 and 350 mL/min were also compared. Results Switching of the dialysis mode from pre-HDF at Q D_total = 500 mL/min to post-HDF at Q D_total = 400 mL/min was not associated with any reduction in the removal efficiency for small molecule solutes. However, the elimination rate of α 1 -microglobulin, a large-middle molecule, increased when the substitution fluid volume was controlled, but decreased when the convection volume (CV) was controlled. There was no difference in the solute removal performance for small to large-middle molecules between post-HDF at Q D_total = 400 and Q D_total = 350 mL/min. Conclusions With post-HDF performed using hemodiafilters of appropriate pore sizes and control of the filtration volume via the CV, the Q D_total could be reduced to 350 mL/min while maintaining efficient removal of small to large molecules. Reduction of water consumption is one of the most immediate countermeasures to combat environmental issues and reducing dialysis fluid consumption is a simple and feasible method to reduce water consumption.