title: Mid-dilution on-line haemodiafiltration in a standard dialyser configuration.
abstract: BACKGROUND
  Mid-dilution haemodiafiltration (HDF) results in an improved middle molecule removal compared with standard HDF. The OLpur MD 190 haemodiafilter represents a new dialyser design exclusively for mid-dilution on-line HDF. Compared with standard haemodialysers, structural changes in the headers allow the infusion of high replacement fluid volumes after a first post-dilution and before a second pre-dilution stage.
  
  
  METHODS
  We compared in vitro the new device [blood flow (QB) 400 ml/min, substitution flow (QS) 100 and 200 ml/min, dialysate flow (QD) 800 ml/min] with a conventional high-flux dialyser of the same surface area in haemodialysis (HD) (QD 500 ml/min) and post-dilution HDF (at QS 60, QD = 500 ml/min and at QS 100, QD = 800 ml/min) modes. Subsequently, we performed an initial clinical application of the new device in six mid-dilution HDF treatments of five end-stage renal disease patients (QB 400 ml/min, QS 200 ml/min, QD 800 ml/min, treatment duration 205+/-23 min).
  
  
  RESULTS
  In vitro urea and beta2-microglobulin clearances in mid-dilution HDF were, respectively, 309.2+/-5.5 and 144.4+/-15.2 ml/min (QS 100) and 321.6+/-4.1 and 204.9+/-4.1 ml/min (QS 200), compared with 278.6+/- 17.2 and 94.0+/-7.6 ml/min in HD, and 310.8+/-10.2 and 123.0+/-6.5 ml/min (QS 60) and 323.6+/-11.2 and 158.0+/-10.3 ml/min (QS 100) in post-dilution HDF. The in vivo trials showed the clinical utility of the device and confirmed the in vitro data: urea and beta2-microglobulin clearances were, respectively, 324.6+/- 10.9 and 207.9+/-29.3 ml/min, while reduction ratios were 75.0+/-5.5 and 83.6+/-4.7%.
  
  
  CONCLUSIONS
  Our preliminary results need confirmation in a prospective cross-over study. However, the Nephros MD 190 haemodiafilter promises to be a true technological step ahead in terms of improved beta2-microglobulin removal.
authors.affiliation: Nephrology, University Hospital, Montpellier, France.
authors.forename: Detlef H
authors.initials: DH
authors.lastname: Krieter
authors.forename: Gregory
authors.initials: G
authors.lastname: Collins
authors.forename: James
authors.initials: J
authors.lastname: Summerton
authors.forename: Edward
authors.initials: E
authors.lastname: Spence
authors.forename: Hélène Leray
authors.initials: HL
authors.lastname: Moragues
authors.forename: Bernard
authors.initials: B
authors.lastname: Canaud
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D004867:Equipment Design; D004869:Equipment Safety; D005260:Female; D017583:Hemodiafiltration / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D066298:In Vitro Techniques; D007676:Kidney Failure, Chronic / Q000175:diagnosis / Q000628:therapy*; D008297:Male; D008567:Membranes, Artificial; D008875:Middle Aged; D006435:Renal Dialysis / Q000295:instrumentation*; D012680:Sensitivity and Specificity; D013673:Technology Assessment, Biomedical
chemical_list: D008567:Membranes, Artificial