Ionic dialysance allows an adequate estimate of urea distribution volume in hemodialysis patients

Ionic dialysance (D) is an online measured variable now available on several dialysis monitors to evaluate small-solute clearance. Based on conductivity measurements in the inlet and outlet dialysate, the principle of the measurement and the different measurement methods are described. Studies that have evaluated the reliability of ionic dialysance to assess dialysis efficiency are discussed. These studies are divided into two groups: the first comparing ionic dialysance to urea clearance and the second comparing Dt/V to Kt/V(urea), in which the uncertainties of the measurement of V(urea) could have misrepresented the relationship between Dt/V and Kt/V(urea). When Kt/V(urea) via the Daugirdas second-generation equation taking the rebound into account is considered, slight-even nonsignificant-differences are evidenced between Kt/V(urea) and Dt/V. Therefore, ionic dialysance should be considered as a valid measure in future guidelines for dialysis efficiency.

supporting

confidence: 53%

Ionic dialysance: Principle and review of its clinical relevance for quantification of hemodialysis efficiency

Mercadal

Ridel

Petitclerc

2005

“…End‐dialysis urea distribution volume (V U t) was determined using D′ cond as input to the 3‐point single‐pool variable‐volume urea kinetic model . V U t was used to estimate end‐dialysis calcium distribution volume (V Ca t) defined as anatomically equal to the extracellular fluid volume and about 1/3 of V u t. D′ cond was also used to calculate in vivo “intrinsic dialysance” for conductivity (KoA cond ) from which calcium dialysance (D′ ca ) was derived …”

Section: Methodsmentioning

confidence: 99%

“…14 End-dialysis urea distribution volume (V U t) was determined using D 0 cond as input to the 3-point single-pool variable-volume urea kinetic model. 18,19 V U t was used to estimate end-dialysis calcium distribution volume (V Ca t) defined as anatomically equal to the extracellular fluid volume and about 1/3 of V u t. D 0 cond was also used to calculate in vivo "intrinsic dialysance" for conductivity (KoA cond ) from which calcium dialysance (D 0 ca ) was derived. 20 A Donnan's factor (a) of 0.938, obtained from previously unpublished data on a HDF technique, Hemo-Filtrate Reinfusion (HFR) able to achieve diffusion and convection separately through two filters in series, 21 was used to account for the amount of plasma water diffusible Ca 2 .…”

Section: Calcium Modelingmentioning

confidence: 99%

Assessment of intradialysis calcium mass balance by a single pool variable‐volume calcium kinetic model

Filippo

Carfagna

Milia

et al. 2017

Self Cite

Introduction: A reliable method of intradialysis calcium mass balance quantification is far from been established. We herein investigated the use of a single-pool variable-volume Calcium kinetic model to assess calcium mass balance in chronic and stable dialysis patients.Methods: Thirty-four patients on thrice-weekly HD were studied during 240 dialysis sessions. All patients were dialyzed with a nominal total calcium concentration of 1.50 mmol/L. The main assumption of the model is that the calcium distribution volume is equal to the extracellular volume during dialysis. This hypothesis is assumed valid if measured and predicted end dialysis plasma water ionized calcium concentrations are equal. A difference between predicted and measured end-dialysis ionized Correspondence to: S. Di Filippo, Division of Nephrology, A. Manzoni Hospital, Via dell'Eremo 9/11, 23900 Lecco, Italy. Email: difilippo.salvatore@libero.it Conflict of Interest: The Authors have nothing to disclose with regards of the present manuscript. Disclosure of grants or other funding: None List of abbreviations: 0-t, Initial and final values; Ca21d, Ionized dialysate calcium concentrations (mmol/L); Ca21di, Dialysate calcium concentration (mmol/L) at the inlet port of dialyzer; Ca21MB, Intra-dialysis ionized calcium mass balance (mmol); Ca21pw, Ionized plasma water calcium concentrations (mmol/L); Ca21pwi, Plasma water calcium concentration (mmol/L) at the inlet port of dialyzer; Ca21pwtM, End-dialysis measured plasma water calcium concentration (mmol/L) normalized at pH 7.40; Ca21pwtP, End-dialysis plasma water calcium concentration (mmol/L) predicted by the model; Ca21pwt(P-M), Difference between end-dialysis plasma water calcium concentration predicted and measured (mmol/L); Ca21uf, Outlet ultrafiltrate stream calcium concentration (mmol/L) normalized at pH 7.40; CaMB, Intra-dialysis global calcium mass balance (mmol); D 0 Ca, Calcium dialysance (L/min) corrected for cardiopulmonary and access recirculation; D 0 cond, Conductivity dialysance (L/ min) corrected for cardiopulmonar and access recirculation; KoAcond, "Intrinsic" dialysance for conductivity (mL/min); MCa21, Mobilization of calcium from extracellular fluid compartment (mmol); Na1d, Ionized dialysate sodium concentrations (mmol/L); Na1pw, Ionized plasma water sodium concentrations (mmol/L); Qbi, Inlet blood flow (mL/min); Qei, Inlet blood water flow (mL/min); Qdi, Inlet dialysate flow (mL/min); Cdi, Inlet dialysate conductivity (mS/cm); Qf, Total ultrafiltrate (L); QfECW, Ultrafiltrate removed from the extracellular fluid compartment (L/min); Qpwi, Inlet plasma water flow (L/min); SPVVCaKM, Single-compartment variable-volume calcium kinetic model; SPVV-NaKM, Single-compartment variable-volume sodium kinetic model; Td, Dialysis session duration (min); VCat, End-dialysis calcium distribution volume (L); Vut, End dialysis urea distribution volume (L); spKt/V, Single Pool Kt/V; a, Donnan factor Predialysis ionized plasma water concentration and total ultrafiltrate were the most imp...

“… spKt/V = obtained from Daugirdas equation using BUN pre‐ and post‐HD; KECN = sodium clearance read from OLC monitor display at end of HD; t = duration of HD treatment; V = TBW. Effective urea clearance estimated from OLC is represented by KECN and was previously shown to be an accurate estimate of blood‐based urea clearance K , and therefore we used KECN as K in Kt / V formula to solve for V . The same or similar approach in adults previously showed that ionic dialysance allows accurate estimation of both V and spKt/V.…”

Section: Methodsmentioning

confidence: 70%

Use of ionic dialysance to calculate Kt/V in pediatric hemodialysis

Marsenić

Booker

Studnicka

et al. 2011

Online clearance (OLC) monitor measures conductivity difference between dialysate entering and leaving the dialyser. Derived ionic dialysance (ID) represents effective urea clearance from which Kt/V is calculated, allowing Kt/V monitoring at every treatment without blood sampling. We tested ID accuracy in children and provide recommendations for its use. Using Fresenius machines 2008 K with built-in OLC monitors, we studied 45 hemodialysis (HD) sessions and 168 calculated Kt/V results in 11 patients. Urea distribution volume (V), needed to calculate Kt/V from ID, was estimated using three methods: Mellits and Cheek (MC), KDOQI recommended total body water nomograms (TBWN) and OLC-derived independent from tested HD sessions. Reference spKt/V from pre- and post-HD BUN (Daugirdas) was compared with Kt/V calculated from ID using three different estimated V's. ID was accurate in calculating Kt/V in children when V derived from OLC was used (P = 0.42), with absolute error 0.14 ± 0.12. If TBWN-derived V was used, Kt/V was consistently underestimated by 0.32 ± 0.22. TBWN-derived V can still be recommended for use with OLC for monitoring trend in Kt/V, if underestimation of spKt/V of average 0.3 is accounted for. MC-derived V results in even greater underestimation of spKt/V and therefore cannot be recommended for use with OLC.