Why should we focus on high-volume hemodiafiltration?

Abstract

Though noticeable technological advances related to hemodialysis (HD) have been made, unfortunately, the survival rate of dialysis patients has yet to improve significantly. However, recent research findings reveal that online hemodiafiltration (HDF) significantly improves patient survival in comparison to conventional HD. Accordingly, the number of patients receiving online HDF is increasing. Although the mechanism driving the benefit has not yet been fully elucidated, survival advantages are mainly related to the lowering of cardiovascular mortality. High cardiovascular mortality among HD patients is seemingly attributable to the cardiovascular changes that occur in response to renal dysfunction and the HD-induced myocardial stress and injury, and online HDF appears to improve such secondary cardiovascular changes. Interestingly, patient survival improves only if the convection volume is supplied sufficiently over a certain level during online HDF treatment. In other words, survival improvement from online HDF is related to convection volume. Therefore, there is a growing interest in high-volume HDF in terms of improving the survival rate. The survival improvement will require a minimum convection volume of 23 L or more per 4-hour session for postdilution HDF. To obtain an optimal high convection volume in online HDF, several factors, such as the treatment time, blood flow rate, filtration fraction, and dialyzer, need to be considered. High-volume HDF can be performed easily and safely in routine clinical practice. Therefore, when the required equipment is available, performing high-volume HDF will help to improve the survival rate of dialysis patients.

Keywords: Chronic kidney failure; Convective therapies; Hemodiafiltration; Mortality; Survival.

Figure 1.. Case of applying a stepwise protocol to obtain the convection volume in the real world.

A 74-year-old female patient with a height of 164 cm and a weight of 114 kg underwent postdilution hemodiafiltration (HDF). Initially, the treatment time was 4 hours, and the blood flow rate (BFR) was 270 mL/min. An increase in the BFR to 300 mL/min led the convection volume to increase to 25.5 L. The treatment time was extended to 4 hours and 30 minutes when the target convection volume of 29 L/session was not reached, even after maximizing the filtration fraction via an auto-substitution (auto-sub) mode. However, the convection volume did not reach the target at 27.5 L. Finally, when the BFR was further increased to 320 mL/min, the convection volume reached 30.2 L.