title: Optimization of dialysate flow in on-line hemodiafiltration.
abstract: BACKGROUND
  Currently, on-line hemodiafiltration (HDF-OL) is the most effective technique. Several randomized studies and meta-analyses have shown a reduced mortality and a direct association with convective volume has been reported. At present, it has not been established if an increased dialysate flow (Qd) results in improved results in terms of convective and depurative efficiency. We aim at assessing the effects of Qd variations on convective volume and its depurative capacity in patients on HDF-OL.
  
  
  METHODS
  A total of 59 patients (45 men and 14 women) from a HDF-OL programme in which a monitor 5008 Cordiax with self-replacement was used, were enrolled. Patients were assessed in 5 sessions with post-dilutional HDF-OL, using helixone-based dialyzers, with only Qd being changed (300, 400, 500, 600 and 700ml/min). Serum levels of urea (60Da), creatinine (113 Da), β2-microglobulin (11,800Da), myoglobin (17,200Da) and α1-microglobulin (33,000Da) were measured at the beginning and at the end of each session, in order to estimate the percent reduction of such solutes.
  
  
  RESULTS
  An increased dialysate volume per session was observed, from 117.9±6.4 L with Qd 300ml/min to 232.4±12 L with Qd 700ml/min. No changes were found in replacement volume or convective volume. Regarding diffusion, Qd increase was associated to a significantly increased dialysis dose, with an increased Kt from 68±6.9 L with Qd 300ml/min to 75.5±7.3 L with Qd 700ml/min (p<0,001), and a gradually increased percent reduction in urea associated to increased Qd with significantly lower levels being found with Qd 300ml/min. No changes were found in other measured substances.
  
  
  CONCLUSIONS
  Qd variations in HDF-OL do not change convective volume. A higher Qd was associated to a slightly increased urea clearance with no change being observed for medium and large molecules. Qd optimisation to the minimal level assuring an adequate dialysis dose and allowing water and dialysate use to be rationalised should be recommended.
authors: Departamento de Nefrología y Trasplante Renal, Hospital Clínic de Barcelona, Barcelona, España. Electronic address: fmaduell@clinic.ub.es.
authors: Francisco
authors: F
authors: Maduell
authors: Departamento de Nefrología y Trasplante Renal, Hospital Clínic de Barcelona, Barcelona, España.
authors: Raquel
authors: R
authors: Ojeda
authors: Departamento de Nefrología y Trasplante Renal, Hospital Clínic de Barcelona, Barcelona, España.
authors: Marta
authors: M
authors: Arias-Guillén
authors: Departamento de Nefrología y Trasplante Renal, Hospital Clínic de Barcelona, Barcelona, España.
authors: Néstor
authors: N
authors: Fontseré
authors: Departamento de Nefrología y Trasplante Renal, Hospital Clínic de Barcelona, Barcelona, España.
authors: Manel
authors: M
authors: Vera
authors: Departamento de Nefrología y Trasplante Renal, Hospital Clínic de Barcelona, Barcelona, España.
authors: Elisabeth
authors: E
authors: Massó
authors: Departamento de Nefrología y Trasplante Renal, Hospital Clínic de Barcelona, Barcelona, España.
authors: Miquel
authors: M
authors: Gómez
authors: Departamento de Nefrología y Trasplante Renal, Hospital Clínic de Barcelona, Barcelona, España.
authors: Lida
authors: L
authors: Rodas
authors: Departamento de Nefrología y Trasplante Renal, Hospital Clínic de Barcelona, Barcelona, España.
authors: Giannina
authors: G
authors: Bazán
authors: Departamento de Nefrología y Trasplante Renal, Hospital Clínic de Barcelona, Barcelona, España.
authors: Mario
authors: M
authors: Jiménez-Hernández
authors: Departamento de Nefrología y Trasplante Renal, Hospital Clínic de Barcelona, Barcelona, España.
authors: Gastón
authors: G
authors: Piñeiro
authors: Departamento de Bioquímica, Hospital Clínic de Barcelona, Barcelona, España.
authors: Nayra
authors: N
authors: Rico
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000510:Alpha-Globulins / Q000032:analysis; D003404:Creatinine / Q000097:blood; D005260:Female; D017583:Hemodiafiltration / Q000295:instrumentation / Q000379:methods*; D015312:Hemodialysis Solutions / Q000008:administration & dosage*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009211:Myoglobin / Q000032:analysis; D009862:Online Systems; D012212:Rheology; D001613:beta 2-Microglobulin / Q000032:analysis
chemical_list: D000510:Alpha-Globulins; D015312:Hemodialysis Solutions; D009211:Myoglobin; C016001:alpha-1-microglobulin; D001613:beta 2-Microglobulin; D003404:Creatinine
keywords: Convective volume; Dialysate flow; Efficacy; Eficacia depurativa; Flujo líquido diálisis; Hemodiafiltración on-line; On-line hemodiafiltration; Volumen convectivo