title: Accuracy and clinical utility of dialysis dose measurement using online ionic dialysance.
abstract: BACKGROUND
  Statistical associations between urea removal and survival have been described in a number of publications. Urea removal during treatment may be quantified by the delivered dose of dialysis. Methods in clinical use to measure delivered dose are retrospective and reliant on accurate blood sampling. The new generation of single patient proportionating systems incorporate the facility to automatically measure ionic dialysance throughout dialysis.
  
  
  METHODS
  In a prospective study on 9 anuric patients with a stable dialysis prescription, we have compared the agreement of the dose of dialysis determined from ionic dialysance (Dt/V) with that derived from equilibriated Kt/V (eKt/V) and Kt/V measured by direct dialysis quantification (Kt/V(DDQ)) using 2 types of hemodialysis membrane (hemophan and low-flux polysulfone). The variability of the delivered dose over a 1-month period was also determined.
  
  
  RESULTS
  Ionic dialysance was independent of membrane type. It was comparable to that established for plasma urea water clearance for hemophan but lower for polysulfone (p < 0.001). The mean (+/- SD) delivered dose of dialysis (Dt/V) was similar for both membranes (1.18 +/- 0.15 (hemophan) and 1.18 +/- 0.11 (low-flux polysulfone)). Bland Altman comparisons showed the limits of agreement between Dt/V and Kt/V(DDQ) were +/- 0.17 and for Dt/V compared with eKt/V +/- 0.15. A 1-month measurement of Dt/V demonstrated considerable treatment to treatment variability indicating that delivered dose cannot be considered stable.
  
  
  CONCLUSIONS
  The availability of online measurement of ionic dialysance provides a step towards monitoring dialysis more closely at the time of delivery, and its clinical application will ensure that a more constant dialysis dose is delivered.
authors.affiliation: Department of Nephrology, School of Clinical Medical Sciences, Medical School, University of Newcastle upon Tyne, UK.
authors.forename: K P
authors.initials: KP
authors.lastname: Katopodis
authors.forename: N A
authors.initials: NA
authors.lastname: Hoenich
mesh_terms: D000328:Adult; D000368:Aged; D015312:Hemodialysis Solutions / Q000008:administration & dosage*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000378:metabolism / Q000628:therapy; D008567:Membranes, Artificial; D008875:Middle Aged; D008954:Models, Biological; D009862:Online Systems; D011446:Prospective Studies; D006435:Renal Dialysis / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D014508:Urea / Q000378:metabolism
chemical_list: D015312:Hemodialysis Solutions; D008567:Membranes, Artificial; D014508:Urea