title: Evaluation of hemodialysis adequacy using online Kt/V and single-pool variable-volume urea Kt/V.
abstract: OBJECTIVE
  The hemodialysis (HD) team should deliver single-pool variable-volume (SPVV) urea Kt/V>or=1.2. At present dialysis machines provide online assessment of Kt/V. The aim of our study is to assess if online Kt/V and SPVV urea Kt/V yield similar values and if it may be replaced in evaluation of HD adequacy.
  
  
  METHODS
  Studies were carried out two times (evaluation I and evaluation II) in 40 patients dialyzed using machines with online Kt/V monitoring by the conductivity method. During the middle HD session in the week, SPVV Kt/V was estimated from urea measurements in serum at the beginning and at the end of the HD session using the second generation formula of Daugirdas. Values of SPVV urea Kt/V and simultaneously obtained online Kt/V were compared.
  
  
  RESULTS
  In I, SPVV Kt/V was 1.37+/-0.16, and online Kt/V was 1.16+/-0.14 (P=0.000), r=0.559 (P=0.000); a regression equation indicated SPVV Kt/V as 0.62457+0.64048 * online Kt/V. In II, estimated SPVV Kt/V was 1.37+/-0.20, online Kt/V-1.16+/-0.15 (P=0.000), r=0.493 (P=0.001), and calculated SPVV Kt/V was 1.37+/-0.10. In I, SPVV urea Kt/V>1.20 was shown in 87.5% of patients, whereas online Kt/V>1.20 was observed in 37.5% of cases (P=0.000). In II, respective values were 82.5% and 40.0% of patients (P=0.000).
  
  
  CONCLUSIONS
  SPVV urea Kt/V indicates a more adequate HD session than online Kt/V. This difference has to be considered when applying Kt/V to clinical practice.
authors.affiliation: Department of Nephrology, Transplantology and Internal Diseases, Karol Marcinkowski University of Medical Sciences, Al. Przybyszewskiego 49, 60-355 Poznan, Poland. alicja_grzegorzewska@yahoo.com
authors.forename: Alicja E
authors.initials: AE
authors.lastname: Grzegorzewska
authors.forename: Wojciech
authors.initials: W
authors.lastname: Banachowicz
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000628:therapy; D007700:Kinetics; D008297:Male; D011237:Predictive Value of Tests; D006435:Renal Dialysis / Q000592:standards*; D018709:Statistics, Nonparametric; D014508:Urea / Q000097:blood*
chemical_list: D014508:Urea