Achieving high convection volumes in postdilution online hemodiafiltration: a prospective multicenter study

Abstract

Background. Available evidence suggests a reduced mortality risk for patients treated with high-volume postdilution hemodiafiltration (HDF) when compared with hemodialysis (HD) patients. As the magnitude of the convection volume depends on treatment-related factors rather than patient-related characteristics, we prospectively investigated whether a high convection volume (defined as ≥22 L/session) is feasible in the majority of patients (>75%). Methods. A multicenter study was performed in adult prevalent dialysis patients. Nonparticipating eligible patients formed the control group. Using a stepwise protocol, treatment time (up to 4 hours), blood flow rate (up to 400 mL/min) and filtration fraction (up to 33%) were optimized as much as possible. The convection volume was determined at the end of this optimization phase and at 4 and 8 weeks thereafter. Results. Baseline characteristics were comparable in participants (n = 86) and controls (n = 58). At the end of the optimization and 8 weeks thereafter, 71/86 (83%) and 66/83 (80%) of the patients achieved high-volume HDF (mean 25.5 ± 3.6 and 26.0 ± 3.4 L/session, respectively). While treatment time remained unaltered, mean blood flow rate increased by 27% and filtration fraction increased by 23%. Patients with <22 L/session had a higher percentage of central venous catheters (CVCs), a shorter treatment time and lower blood flow rate when compared with patients with ≥22 L/session. Conclusions. High-volume HDF is feasible in a clear majority of dialysis patients. Since none of the patients agreed to increase treatment time, these findings indicate that high-volume HDF is feasible just by increasing blood flow rate and filtration fraction.

Effects of Hemodiafiltration versus Conventional Hemodialysis in Children with ESKD: The HDF, Heart and Height Study

“…30 In 3H we demonstrated that a high convection volume of 12-15 L/m 2 body surface area, equating to 20-23 L/session in adults, can be achieved in children by optimizing blood flow and setting a high filtration fraction (up to 33%) without increasing treatment time, as shown in adult patients on HDF. 31 Second, it has been suggested that optimal vascular access, and therefore improved blood flows, are associated with superior outcomes, irrespective of HD or HDF modality, 32 and randomization imbalance by vascular access may have confounded some previous RCTs. 19,23,32 In 3H, blood flow rates were comparable in both arms and independent of vascular access type, implying that any perceived benefits of improved blood flow alone did not account for improved outcomes.…”

Assessment of the influence of expanded hemodialysis on the rate of removal of middle molecular weight uremic toxins

“…Beta-2-microglobulin is a medium molecular weight uremic toxin (MW -11.8 kDa), soluble in water, and an increase in its serum concentration results in the development of dialysis-related amyloidosis -DRA (Dialysis-Related Amyloidosis) (23)(24)(25). In patients treated with regular hemodialysis, the serum β2microglobulin concentration before a single dialysis session should be  30 mg/L (23-25).…”

Benefits and harms of high-dose haemodiafiltration versus high-flux haemodialysis: the comparison of high-dose haemodiafiltration with high-flux haemodialysis (CONVINCE) trial protocol

“…High-dose HDF is defined as a convection volume of ≥23 L (range ±1 L). Previous studies have shown that it is also possible to achieve these convection volumes in older patients with comorbidities 24 25. In cases where the target convection volume (≥23 L/ session; range ±1 L) is not initially achieved, then steps should be undertaken in an effort to achieve the target convection volume which may require a stepwise adjustment of dialysis prescription to achieve this target over 2–3 weeks (online supplementary appendices 1-3 and table 2).…”

“…In cases where the target convection volume (≥23 L/ session; range ±1 L) is not initially achieved, then steps should be undertaken in an effort to achieve the target convection volume which may require a stepwise adjustment of dialysis prescription to achieve this target over 2–3 weeks (online supplementary appendices 1-3 and table 2). 25 26 If the target convection volume still cannot be reached after these steps, then the highest volume possible should be used. Convection volume, and reasons why the target could not be reached, should be recorded into the electronic study case record form (eCRF).…”