title: What is the optimum dialysate flow in post-dilution online haemodiafiltration?
abstract: BACKGROUND
  In post-dilution online hemodiafiltration (OL-HDF), the only recommendation concerning the dialysate, or dialysis fluid, refers to its purity. No study has yet determined whether using a high dialysate flow (Qd) is useful for increasing Kt or ultrafiltration-infusion volume.
  
  
  OBJECTIVE
  Study the influence of Qd on Kt and on infusion volume in OL-HDF.
  
  
  METHODS
  This was a prospective crossover study. There were 37 patients to whom 6 sessions of OL-HDF were administered at 3 different Qds: 500, 600 and 700ml/min. A 5008(®) monitor was used for the dialysis in 21 patients, while an AK-200(®) was used in 17. The dialysers used were: 20 with FX 800(®) and 17 with Polyflux-210(®). The rest of the parameters were kept constant. Monitor data collected were effective blood flow, effective dialysis time, final Kt and infused volume.
  
  
  RESULTS
  We found that using a Qd of 600 or 700ml/min increased Kt by 1.7% compared to using a Qd of 500ml/min. Differences in infusion volume were not significant. Increasing Qd from 500ml/min to 600 and 700ml/min increased dialysate consumption by 20% and 40%, respectively.
  
  
  CONCLUSIONS
  With the monitors and dialysers currently used in OL-HDF, a Qd higher than 500ml/min is unhelpful for increasing the efficacy of Kt or infusion volume. Consequently, using a high Qd wastes water, a truly important resource both from the ecological and economic points of view.
authors.affiliation: Servicio de Nefrología, Hospital Infanta Leonor, Madrid, España. Electronic address: malbalater@senefro.org.
authors.forename: Marta
authors.initials: M
authors.lastname: Albalate Ramón
authors.affiliation: Servicio de Nefrología, Hospital Infanta Leonor, Madrid, España.
authors.forename: Patricia
authors.initials: P
authors.lastname: de Sequera Ortiz
authors.affiliation: Servicio de Nefrología, Hospital Infanta Leonor, Madrid, España.
authors.forename: Rafael
authors.initials: R
authors.lastname: Pérez-García
authors.affiliation: Servicio de Nefrología, Hospital Infanta Leonor, Madrid, España.
authors.forename: Elena
authors.initials: E
authors.lastname: Corchete Prats
authors.affiliation: Servicio de Nefrología, Hospital Infanta Leonor, Madrid, España.
authors.forename: Roberto
authors.initials: R
authors.lastname: Alcázar Arroyo
authors.affiliation: Servicio de Nefrología, Hospital Infanta Leonor, Madrid, España.
authors.forename: Mayra
authors.initials: M
authors.lastname: Ortega Díaz
authors.affiliation: Servicio de Nefrología, Hospital Infanta Leonor, Madrid, España.
authors.forename: Marta
authors.initials: M
authors.lastname: Puerta Carretero
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003247:Conservation of Natural Resources; D003365:Costs and Cost Analysis; D018592:Cross-Over Studies; D015314:Dialysis Solutions / Q000191:economics / Q000493:pharmacokinetics*; D005260:Female; D017583:Hemodiafiltration / Q000191:economics / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000628:therapy*; D008297:Male; D008567:Membranes, Artificial; D008875:Middle Aged; D011446:Prospective Studies; D012212:Rheology; D014867:Water
chemical_list: D015314:Dialysis Solutions; D008567:Membranes, Artificial; D014867:Water
keywords: Dialysate flow rate; Flujo de infusión; Flujo de líquido de diálisis; Hemodiafiltración en línea; Hemodiafiltration on-line; Infusion volume; Kt