title: New strategies in haemodiafiltration (HDF): prospective comparative analysis between on-line mixed HDF and mid-dilution HDF.
abstract: BACKGROUND
  Improvement in the uraemic toxicity profile obtained with the application of convective and mixed dialysis techniques has stimulated the development of more efficient strategies. Our study was a prospective randomized evaluation of the clinical and technical characteristics of two new haemodiafiltration (HDF) strategies, mixed HDF and mid-dilution HDF, which have recently been proposed with the aim of increasing efficiency and safety with respect to the standard traditional HDF infusion modes.
  
  
  METHODS
  Ten stable patients on renal replacement therapy (mean age 64.7 +/- 8.2 years) were submitted in randomized sequence to one mid-week session of mid-dilution HDF and one of mixed HDF with trans-membrane pressure feedback control. All sessions were carried out under similar operating conditions and involved monitoring pressure within the internal dialyser compartments and calculating the rheological and hydraulic indexes. Efficiency in removing urea, phosphate and beta2-microglobulin (beta2-m) was tested.
  
  
  RESULTS
  In mixed HDF, safer and more effective flux/pressure conditions resulted in better preservation of the hydraulic and solute membrane permeability (mean in vivo ultrafiltration coefficient 36.9 +/- 3.9 vs 20.1 +/- 3.3 ml/h/mmHg) and ensured higher volume exchange (38.7 +/- 4.2 vs 35.3 +/- 6.5 l/session, P = 0.02) and greater efficiency in removing small and middle molecules (mean urea clearance: 274 +/- 42 vs 264 +/- 47 ml/min, P = 0.028; eKt/V: 1.78 +/- 0.22 vs 1.71 +/- 0.26, P = 0.036; mean phosphate clearance: 138 +/- 16 vs 116 +/- 45 ml/min, P = 0.2; mean beta2-m clearance: 81 +/- 13 vs 59 +/- 13 ml/min, P = 0.001).
  
  
  CONCLUSIONS
  Mixed HDF was the most efficient technique in the highest range of safe operating conditions. In mid-dilution HDF, high pressures generated inside the dialyser compromised membrane permeability and limited the total infusion rate, resulting in an overall reduction in solute removal.
authors.affiliation: Department of Nephrology and Dialysis, Ospedale Bolognini, 24068-SERIATE, Bergamo, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Feliciani
authors.forename: Maria Alessandra
authors.initials: MA
authors.lastname: Riva
authors.forename: Simona
authors.initials: S
authors.lastname: Zerbi
authors.forename: Pio
authors.initials: P
authors.lastname: Ruggiero
authors.forename: Anna Rita
authors.initials: AR
authors.lastname: Plati
authors.forename: Giorgio
authors.initials: G
authors.lastname: Cozzi
authors.forename: Luciano A
authors.initials: LA
authors.lastname: Pedrini
mesh_terms: D005260:Female; D017583:Hemodiafiltration / Q000379:methods* / Q000639:trends; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D011312:Pressure; D011446:Prospective Studies