Effective Diffusion Volume Flow Rates (Qe) for Urea, Creatinine, and Inorganic Phosphorous (Qeu, Qecr, QeiP) during Hemodialysis

Frank A. Gotch, Froilan Panlilio, Olga Sergeyeva, Laura Rosales, Tom Folden, George Kaysen, Nathan Levin

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


In vivo solute clearances can be estimated from dialyzer blood (Q b) and dialysate (Qd) flow rates and a solute- and dialyzer-specific overall permeability membrane area product (KoA). However, these calculations require knowledge of the flow rate of the effective solute distribution volume in the flowing bloodstream (Qe) in order to calculate in vivo clearances and KoAs. We have determined Qe for urea, creatinine, and inorganic phosphorus from changes in concentrations across the blood compartment and mass balance between the blood and dialysate streams. We made four serial measurements over one dialysis in 23 patients and found that Qeu equals the total blood water flow rate, Q ecr equals the plasma water flow rate plus 61% of red cell Water flow rate, and QeiP is limited to the plasma water flow rate. Equations are derived to calculate Qe for each of these solutes from Qb and hematocrit and in vivo KoAs for each solute were calculated.

Original languageEnglish (US)
Pages (from-to)474-476
Number of pages3
JournalSeminars in Dialysis
Issue number6
StatePublished - Nov 2003

ASJC Scopus subject areas

  • Nephrology


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