Increasing Dialysate Flow Rate over 500 ml/min for Reused High-Flux Dialyzers do not Increase Delivered Dialysis Dose: A Prospective Randomized Cross Over Study

Objective: The primary objectives were: 1) to study the impact of Qd (500 vs 800 ml/min) on the delivered dose by reused dialyzers, and 2) to determine dialysis efficiency of a dialyzer reused 15 times. Materials and Methods: A prospective randomized-controlled crossover study was conducted in 42 thrice-weekly hemodialysis (HD) patients (630 HD sessions in each Qd). Delivered doses at both Qds were assessed by single-pool Kt/V (spKt/V), equilibrated Kt/V (eKt/V) and online clearance monitoring Kt/V (Kt/VOCM), measured at mid-week HD session using a new dialyzer and then again at every mid-week HD session. Results: Although the spKt/V in HD sessions using new dialyzers at Qd of 500 ml/min was slightly lower than spKt/V at Qd of 800 ml/min (2.19±0.08 vs. 2.34±0.08, respectively, P=0.04), when accounting for urea rebound as assessed by eKt/V and Kt/V_OCM, there was no significant difference. The average delivered doses in dialyzers reused 15 times, with the mean average of spKt/V, eKt/V and Kt/V_OCM at Qd 500 ml/min, were not significantly inferior to the delivered doses at Qd 800 ml/min. Reusing a dialyzer 15 times did not decrease dialysis efficiency and delivered doses in all HD sessions reached spKt/V >1.4. Conclusion: Increasing Qd over 500 ml/min for modern dialyzers does not significantly increase delivered dose of dialysis.