Differential Molecular Modeling Predictions of Mid and Conventional Dialysate Flows

Abstract

Background: High dialysate flow rates (Q_D) of 500–800 mL/min are used to maximize urea removal during conventional hemodialysis. There are few data describing hemodialysis with use of mid-rate Q_D (300 mL/min). Methods: We constructed uremic solute (urea, beta₂-microglobulin and phosphate) kinetic models at varying volumes of distribution and blood flow rates to predict solute clearances at Q_D of 300 and 500 mL/min. Results: Across a range of volumes of distribution a Q_D of 300 mL/min generally yields a predicted urea spKt/V greater than 1.2 during typical treatment times with a small difference in urea spKt/V between a Q_D of 300 and 500 mL/min. A larger urea KoA dialyzer and 15 min of additional time narrows the urea spKt/V difference. No substantial differences were observed regarding the kinetics of beta₂-microglobulin and phosphate for Q_D of 300 vs. 500 mL/min. Conclusion: A Q_D of 300 mL/min can achieve urea clearance targets. Hemodialysis systems using mid-rate Q_D can be expected to provide adequate hemodialysis, as currently defined.

Updates on hemodialysis techniques with a common denominator: The personalization of the dialytic therapy

“…Several studies revealed that dialysate flow higher than 500 ml/min was unhelpful for increasing the dialysis efficacy or infusion volume, with consequently important implications both from the ecological and economic points of view. [47][48][49] The CONVINCE study has recently started, enrolling 1800 patients in multiple European countries, with the main objective to compare standard high-flux HD and HDF, delivered in high volume (post-dilution >23 L/4 h session), in terms of morbidity, mortality, and Health-related Quality of Life. 50 This large, international, multicenter, randomized controlled trial, over a 3-year follow-up period, should finally deliver the undisputable answer about the superiority between the different dialytic techniques.…”

“…Moreover, in post‐dilution HDF, the only recommendation concerning the dialysate, or dialysis fluid, refers to its purity. Several studies revealed that dialysate flow higher than 500 ml/min was unhelpful for increasing the dialysis efficacy or infusion volume, with consequently important implications both from the ecological and economic points of view 47‐49 …”

Severe methanol poisoning treated with a novel hemodialysis system: a case report, analysis, and review

“…The maximum Qd accommodated by Tablo is 300 mL/min. A recent kinetic modeling analysis of the effect of decreasing Qd from 500 to 300 mL/min at Qb rates of 300–400 mL/min concluded that the resulting drop in equilibrated Kt/V urea would be relatively small at 0.12–0.22, a difference that could be nearly fully counteracted by using a dialyzer with a higher K O A (1480 versus 1170 mL/min) and extending treatment time by 15 min [ 30 ]. A recent in vivo study of six patients on maintenance dialysis sequentially treated with Tablo with a Qd of 300 mL/min and a conventional IHD machine (Gambro Phoenix) with Qd of 500 mL/min yielded clearance curves for urea, potassium, phosphate, and β 2 -microglobuin which were remarkably similar, with no statistically significant difference in the levels of any of the four solutes by the end of 4 h of treatment despite the differing Qd rates [ 27 ].…”