Pilot study to assess increased dialysis efficiency in patients with limited blood flow rates due to vascular access problems

In the last few years, the number of hemodialysis patients with inadequate blood flow (Qb) rates has increased due to vascular access problems. To avoid a clinical status of underdialysis, these patients need long-lasting dialysis sessions. However, other factors aimed to optimize the dialysis dose have to be considered. High-efficiency convective therapies, such as online hemodiafiltration (HDF), are claimed to be superior to high-flux hemodialysis (HF-HD) in improving the dialysis efficacy, but treatment efficacy is strongly related to blood flow rate and infusion volumes. Online mid-dilution (HDF-MD) with the Nephros OL-pure MD190 represents a new HDF concept to increase the removal of middle molecules. In a cross-over clinical trial, 8 patients, with Qb eff <300 mL/min, received either online HDF-MD or HF-HD; Qd was 700 mL/min, the time duration was 240 min, and the filtration volume in HDF-MD was 112±7 mL/min. No differences were found for Kt/V, urea, and creatinine clearances. Clearance of both small phosphate (P) large β2-microglobulin (β2m), and leptin (L) solutes was significantly greater for MD (P 217±32, β2m 85.5±10, L 42.6±18 mL/min) than for HF-HD (P 178±32, β2m 71.9±13, L 32.1±12 mL/min). The results of this study indicate that HDF remains the best means of providing increased removal of large-molecular weight solutes even in patients with vascular access problems.