Introduction:
Dialysis adequacy is a key factor determining clinical outcomes for patients with end-stage kidney disease (ESKD) undergoing maintenance dialysis. Traditionally, dialysis dosing has been based on plasma urea removal, quantified using Kt/Vurea with total body water calculated using Watson equation or bioimpedance analysis (BIA). The traditional Kt/Vurea calculation equations methods were devised for haemodialysis sessions and are extrapolated to hemodiafiltration (HDF) sessions in current clinical practice. With emerging benefits and increasing use of HDF worldwide, there is a need to validate existing Kt/Vurea equations for HDF treatments. This study aimed to compare urea clearance estimated from traditional Kt/Vurea equations with direct measurements of urea in spent dialysate in a cohort of patients undergoing maintenance dialysis by predominantly HDF mode.
Methods:
We conducted a study involving adult patients on maintenance dialysis comparing Kt/Vurea estimates from pre- and post-dialysis blood samples with urea clearance measured from spent dialysate. Effective ionic dialysance (EID) was monitored using Online Clearance Monitoring (OLC™), and dialysate conductivity and urea concentrations were measured. Total body water (TBW) was estimated using the Watson equation and BIA. Urea clearance from spent dialysate was compared with estimates from standard Kt/V equations and OLC™ measurements.
Results:
We evaluated urea clearance in 41 patients (56.1% male, mean age 69.3 ± 12.6 years), with 87.8% receiving hemodiafiltration. The reduction in total body urea was greater when estimated from changes in total body urea ((71.6% [62.1-78], p < 0.01) compared to measured dialysate losses ((58.4% [48.5-67.6]) ). Session-specific urea clearance (Kt/Vurea) was higher using the online Solute-Solver program, with a median of 1.45 (1.13-1.75), compared to OLC™ (1.2 [0.93-1.4]) and the second-generation Kt/V equations (1.3 [1.02-1.66], p < 0.01). However, there was no significant difference compared to estimates based on total body urea clearance (1.36 [1.15-1.73]) or measured dialysate clearance (1.36 [1.07-1.76]). The mean bias compared to the Solute-Solver program was greatest with OLC™ (-0.25), compared to the second-generation equations (-0.02), estimated total body clearance (-0.02), and measured dialysate clearance (-0.01).
Conclusions:
Our study demonstrated a high degree of reliability between direct measurements of urea clearance from spent dialysate and various Kt/Vurea calculation methods. Despite some discrepancies, the overall agreement supports the continued use of updated Kt/Vurea equations and direct measurement techniques in assessing dialysis adequacy.
This abstract was also submitted for publication in artificial organs. The journal had no objections to presentation of this abstract.
I have no potential conflict of interest to disclose.
I did not use generative AI and AI-assisted technologies in the writing process.