title: Dialysate flow rate and delivered Kt/Vurea for dialyzers with enhanced dialysate flow distribution.
abstract: OBJECTIVE
  Previous in vitro and clinical studies showed that the urea mass transfer-area coefficient (K(o)A) increased with increasing dialysate flow rate. This observation led to increased dialysate flow rates in an attempt to maximize the delivered dose of dialysis (Kt/V(urea)). Recently, we showed that urea K(o)A was independent of dialysate flow rate in the range 500 to 800 ml/min for dialyzers incorporating features to enhance dialysate flow distribution, suggesting that increasing the dialysate flow rate with such dialyzers would not significantly increase delivered Kt/V(urea).
  
  
  METHODS
  We performed a multi-center randomized clinical trial to compare delivered Kt/V(urea) at dialysate flow rates of 600 and 800 ml/min in 42 patients. All other aspects of the dialysis prescription, including treatment time, blood flow rate, and dialyzer, were kept constant for a given patient. Delivered single-pool and equilibrated Kt/V(urea) were calculated from pre- and postdialysis plasma urea concentrations, and ionic Kt/V was determined from serial measurements of ionic dialysance made throughout each treatment.
  
  
  RESULTS
  Delivered Kt/V(urea) differed between centers; however, the difference in Kt/V(urea) between dialysate flow rates of 800 and 600 ml/min was NS by any measure (95% confidence intervals of -0.064 to 0.024 for single-pool Kt/V(urea), -0.051 to 0.023 for equilibrated Kt/V(urea), and -0.029 to 0.099 for ionic Kt/V).
  
  
  CONCLUSIONS
  These data suggest that increasing the dialysate flow rate beyond 600 ml/min for these dialyzers offers no benefit in terms of delivered Kt/V(urea).
authors.affiliation: Department of Medicine, University of Louisville, Louisville, Kentucky, USA. richard.ward@louisville.edu
authors.forename: Richard A
authors.initials: RA
authors.lastname: Ward
authors.forename: John W
authors.initials: JW
authors.lastname: Idoux
authors.forename: Hiba
authors.initials: H
authors.lastname: Hamdan
authors.forename: Rosemary
authors.initials: R
authors.lastname: Ouseph
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Depner
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Golper
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018592:Cross-Over Studies; D015314:Dialysis Solutions; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis / Q000295:instrumentation*; D014508:Urea / Q000097:blood*
chemical_list: D015314:Dialysis Solutions; D014508:Urea