Daily dialysis Kt/V and flexible schedules: is it possible to control efficiency, when and how?

Background: Daily hemodialysis is a promising treatment schedule but unifor m criteria for defining efficiency are lacking. Methods: On our daily dialy sis (DD) schedule, duration is flexible (2-3 hours, patients are free to ad d up to 30min/session), Qb 250-350 mL/min; dialyser 1.6-1.8 m(2). Study was performed on 12 pts on DD for greater than or equal to2 months, with great er than or equal to4 Kt/V on subsequent days, tested in the same laboratory . Goal: To evaluate variability and identify a simple method for weekly cal culation, Kt/V was assessed for 133 sessions. Results: On flexible DD, variability of Kt/V-session is high (relative erro r 4.9%-22%). On flexible schedules, within the time range chosen (2-3 hours ) variability of average hourly Kt/V is lower (standard deviation: min (0.0 14; max (0.052 hour, relative error 4.9%-10%) allowing calculation of weekl y Kt/V (averaging 3 sessions: relative error (<6%) suitable for clinical pr actice. Conclusions: Flexible schedules, allowing patients to increase treatment ti me, are an interesting clinical option, but a challenge for Kt/V assessment .