Mixed- versus predilution hemodiafiltration effects on convection volume and small and middle molecule clearance in hemodialysis patients: a prospective randomized controlled trial

Abstract

Background: The use of newly developed mixed-dilution hemodiafiltration (HDF) can supplement the weaknesses of pre-and postdilution HDF. However, it is unclear whether mixed-HDF performs well compared to predilution HDF. Methods: We conducted a prospective, open-labeled, randomized controlled trial from two hemodialysis centers in Korea. Between January 2017 and September 2019, 60 patients who underwent chronic hemodialysis were randomly assigned at a 1:1 ratio to receive either predilution HDF (n = 30) or mixed-HDF (n = 30) for 6 months. We compared convection volume, changes in small-and medium-sized molecule clearance, high-sensitive C-reactive protein (hs-CRP) level, and dialysis-related parameters between the two dialysis modalities. Results: A mean effective convection volume of 41.0 ± 10.3 L/session in the predilution HDF group and 51.5 ± 9.0 L/session in the mixed-HDF group was obtained by averaging values of three time-points. The difference in effective convection volume between the groups was 10.5 ± 1.3 L/session. This met the preset noninferiority criteria, suggesting that mixed-HDF was noninferior to predilution HDF. Moreover, the β2-microglobulin reduction rate was greater in the mixed-HDF group than in the predilution HDF group, while mixed-HDF provided greater transmembrane pressure. There were no significant between-group differences in Kt/V urea levels, changes in predialysis hs-CRP levels, proportions of overhydration, or blood pressure values. Symptomatic intradialytic hypotension episodes and other adverse events occurred similarly in the two groups. Conclusion: Use of mixed-HDF was comparable to predilution HDF in terms of delivered convection volume and clinical parameters. Moreover, mixed-HDF provided better β2-microglobulin clearance than predilution HDF.

Convection volume, β2‐microglobulin and α1‐microglobulin reduction ratios, and body composition in pre‐dilution online haemodiafiltration

“…Clinical and corporal composition data collected from the institutional medical record were as follows: age, sex, primary kidney disease, dialysis vintage, presence of diabetes, pre‐ and post‐dialysis weight, and post‐dialysis body mass index (BMI), Kt/V urea , serum albumin, creatinine, phosphate, calcium, magnesium and C‐reactive protein (CRP), normalized protein catabolic rate (nPCR), 9 geriatric nutritional index (GNRI), 10 cholesterols and triglycerides. Dialysis conditions comprising time, substitution volume, blood flow, dialysate flow, ultrafiltration volume (UF), intradialytic weight loss and CV (UF + substitution volume) 11,12 were collected. Same day body composition data assessed 30 min after Post‐OL‐HDF sessions using a bioimpedance spectroscopy device (BCM®: Fresenius Medical Care, Buzen city, Japan) were also collected.…”

“…Pre-OL-HDF, pre-dilution online haemodiafiltration; Convection volume = ultrafiltration volume + substitution volume; OH, overhydration (excess fluid = difference between normal extracellular water and measured extracellular water). 13 + substitution volume) 11,12 were collected. Same day body composition data assessed 30 min after Post-OL-HDF sessions using a bioimpedance spectroscopy device (BCM ® : Fresenius Medical Care, Buzen city, Japan) were also collected.…”

Online Hemodiafiltration Compared to Conventional Hemodialysis in Critically Ill Patients

“…Corrected convection volume was calculated in liters (L) by adding the substitution volume to the net ultrafiltration volume removed during the session. When pre-dilution method was used, the substitution volume was divided by half to account for the reduced clearance associated with this method in accordance to usual practice in patients with end-stage kidney disease 25,26,27 .…”

Who is the winner, pre-, post-, or mixed-dilution hemodiafiltration?

“…In this issue of Kidney Research and Clinical Practice, Park et al [8] conducted a randomized controlled trial to compare convection volume and solute clearance between predilution HDF and mixed dilution HDF in patients receiving maintenance HD. The mixed dilution mode was not inferior to the predilution mode considering effective convection volume (51.5 ± 9.0 L/session vs. 41.0 ± 10.3 L/session, respectively).…”

“…Since predilution HDF uses twice as much replacement fluid as the postdilution mode, the effective convection volume for mixed dilution HDF can be calculated as follows as the authors suggested: effective convection volume = substitution volume in predilution mode + (2 × substitution volume in postdilution mode) + ultrafiltration volume [8]. In this regard, the effective convection volume can be used instead of absolute convection volume when comparing the convection volumes between predilution and mixed dilution HDF.…”