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Abstract: PO1093

Intradialytic Online Multicomponent Total Removed Solute Monitoring in Spent Dialysate by a Novel Miniaturized Optical Sensor

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis


  • Leis, Liisi, North Estonia Medical Centre, Tallinn, Estonia
  • Adoberg, Annika, North Estonia Medical Centre, Tallinn, Estonia
  • Paats, Joosep, Tallinn University of Technology, Tallinn, Estonia
  • Arund, Jürgen, Tallinn University of Technology, Tallinn, Estonia
  • Pilt, Kristjan, Tallinn University of Technology, Tallinn, Estonia
  • Luman, Merike, North Estonia Medical Centre, Tallinn, Estonia
  • Fridolin, Ivo, Tallinn University of Technology, Tallinn, Estonia

Urea is the most commonly exploited marker of dialysis adequacy, but also other uremic retention solutes accumulate in ESKD patients. Commonly, the uremic solutes are divided into three physicochemical types with the representative markers urea, uric acid (UA); indoxyl sulfate (IS); and β2-microglobulin (B2M).
Instead of total dialysate collection for quantification of the amount of uremic solutes removed during dialysis, an optical on-line monitoring has been proposed.
The aim of this study was to evaluate intradialytic on-line multicomponent total removed solute (TRS) monitoring in the spent dialysate by a novel miniaturized optical sensor during hemodialysis (HD) and hemodiafiltration (HDF) with different settings.


Ten ESKD patients (6 M, 4 F; 60.2±16.8 y.o.) on chronic HDF were enrolled into the study. For each patient 5 midweek dialysis sessions
(240min; HD: N=1, Qb=200mL/min, Qd=300mL/min, 1,5m2 ; HDF: N=4, Qb≥300mL/min, Qd≥500mL/min, Vsubst≥15L, 1,8m2 and 2,2m2 ) were included. Spent dialysate from the drain was monitored on-line by a miniaturized sensor prototype (Optofluid Technologies OÜ, Estonia). For the reference, samples from the spent dialysate drain tube of the HD machine were taken 7, 60, 120, 180 and 240 min after the start of the dialysis session. Concentrations of urea and B2M in the dialysate were determined in the clinical laboratory. Concentrations of IS and UA were determined utilizing the HPLC. TRS values were calculated using the tank weight and the lab or optical tank solute concentrations. t-test was used to determine significant differences between the methods (P≤0.05).


The laboratory and optical TRS values were 489±112mmol and 512±87mmol for urea (R2=0.215), 4232±712µmol and 4331±756µmol for UA (R2=0.829), 230±47mg and 231±40mg for B2M (R2=0.551), 606±339µmol and 616±321µmol for IS (R2=0.951), being not statistically different for any uremic solutes. The reason for higher correlation for UA and IS is direct measurements of UA and IS by the optical sensor whereas urea and B2M are estimated indirectly.


Novel miniaturized optical sensor successfully carried out intradialytic on-line multicomponent TRS monitoring for the uremic solutes urea, UA, B2M and IS in the spent dialysate.