title: Theoretical basis for and improvement of Daugirdas' second generation formula for single-pool Kt/V.
abstract: OBJECTIVE
  An empirically-derived equation to estimate hemodialysis treatment variable-volume single-pool Kt/V, where Kt/V = -In(R-GFAC × t) + (4-3.5 × R) × UFV/W, was published in 1993 (1) and quickly became a standard tool for the estimation of dialysis dose. We aim to find a theoretical basis for this equation.
  
  
  METHODS
  A mathematical derivation is used to find the connection between Kt/V and modeled urea concentrations.
  
  
  RESULTS
  There is a theoretical basis for the empirical structure of the estimating equation, but the estimation of the effect of ultrafiltration on Kt/V can be improved. Finally, we show that the accuracy of the formula may be suboptimal for some extreme dialysis schedules and propose a new equation that is more robust across atypical dialysis prescriptions.
  
  
  CONCLUSIONS
  The currently used Kt/V estimating equation has a sound theoretical basis and an improved version is proposed that can maintain accuracy with a broader range of fluid removal.
authors.affiliation: Baxter International, Lund - Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Sternby
authors.affiliation: University of Illinois at Chicago, Chicago, IL - USA.
authors.forename: John T
authors.initials: JT
authors.lastname: Daugirdas
mesh_terms: D015415:Biomarkers / Q000097:blood; D001834:Body Water / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D007674:Kidney Diseases / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D007700:Kinetics; D008954:Models, Biological; D011237:Predictive Value of Tests; D006435:Renal Dialysis / Q000379:methods*; D016896:Treatment Outcome; D014508:Urea / Q000097:blood*
chemical_list: D015415:Biomarkers; D014508:Urea