title: Clinical cross-over comparison of mid-dilution hemodiafiltration using a novel dialyzer concept and post-dilution hemodiafiltration.
abstract: BACKGROUND
  Several studies have indicated that the improved elimination of middle molecules by convective renal replacement procedures might be associated with a better outcome in end-stage renal disease (ESRD). On-line mid-dilution hemodiafiltration (HDF) with the Nephros OLpur MD 190 hemodiafilter represents a novel extracorporeal renal replacement therapy concept to increase the removal of middle molecules.
  
  
  METHODS
  In a prospective cross-over study in 10 ESRD patients, this technique was compared to on-line post-dilution HDF with a conventional synthetic high-flux dialyzer, operated at its technical limit, concerning small and middle molecular solute removal. Each patient was treated 3 times for 4.0 +/- 0.4 hours with both filters. Blood flow was 400 mL/min, substitution flow (Q(S)) during mid-dilution HDF 200 mL/min, and during post-dilution HDF 100 mL/min, and effective dialysate flow of 700 - Q(S) mL/min. Instantaneous clearances, reduction ratios (RR), and middle molecule mass transfer in continuously collected dialysate were determined.
  
  
  RESULTS
  While urea and creatinine clearances were significantly lower (6.4% and 3.9%, respectively), middle molecule removal was much more efficient in mid-dilution HDF over the whole range of investigated proteins: compared to post-dilution HDF, beta(2)-microglobulin (11.8 kD) clearance (165.8 +/- 26.59 vs. 201.9 +/- 20.63 mL/min; P < 0.001), RR (80.0 +/- 5.4% vs. 82.2 +/- 5.7%; P < 0.001), and dialysate mass transfer (53% higher; P < 0.001) were significantly higher. For the larger middle molecules, cystatin C (13.4 kD) and retinol-binding protein (21.2 kD), mid-dilution HDF resulted in an even more superior performance, indicated by significantly higher values of all investigated parameters.
  
  
  CONCLUSIONS
  On-line mid-dilution HDF with the Nephros OLpur MD 190 hemodiafilter appears to be a true technologic step ahead in terms of improved middle molecule removal. This efficient procedure gives hope to play a role in preventing or at least retarding dialysis-related long-term complications, such as beta(2)m amyloidosis, in ESRD patients, and may contribute to a more adequate dialysis therapy.
authors.affiliation: Department of Nephrology, University of Montpellier, and U.D.S.A.-A.I.D.E.R., Clinique Jaques Mirouze, Montpellier, France. krieter_D@medizin.uni-wuerzburg.de
authors.forename: Detlef H
authors.initials: DH
authors.lastname: Krieter
authors.forename: Sven
authors.initials: S
authors.lastname: Falkenhain
authors.forename: Lotfi
authors.initials: L
authors.lastname: Chalabi
authors.forename: Gregory
authors.initials: G
authors.lastname: Collins
authors.forename: Horst-Dieter
authors.initials: HD
authors.lastname: Lemke
authors.forename: Bernard
authors.initials: B
authors.lastname: Canaud
mesh_terms: D000328:Adult; D000368:Aged; D001798:Blood Proteins / Q000737:chemistry / Q000378:metabolism; D018592:Cross-Over Studies; D055316:Cystatin C; D015891:Cystatins / Q000097:blood; D004867:Equipment Design; D005260:Female; D017583:Hemodiafiltration / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D008970:Molecular Weight; D011446:Prospective Studies; D012177:Retinol-Binding Proteins / Q000378:metabolism; D014118:Toxins, Biological / Q000097:blood / Q000302:isolation & purification; D014508:Urea / Q000097:blood; D001613:beta 2-Microglobulin / Q000097:blood
chemical_list: D001798:Blood Proteins; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D012177:Retinol-Binding Proteins; D014118:Toxins, Biological; D001613:beta 2-Microglobulin; C026865:uremia middle molecule toxins; D014508:Urea