Squared frequency-Kt/V: A new index of hemodialysis adequacy-correlation with solute concentrations by computer simulation

Abstract

Background: In patients undergoing home dialysis, conventionally, Kt/V has been regarded as an index of the removal efficiency per dialysis session. However, more recently, it has been considered that the hemodialysis product (HDP), rather than the Kt/V, is better associated with the clinical symptoms and outcomes in patients undergoing short daily dialysis or nocturnal dialysis. Nevertheless, the HDP lacks a theoretical background, and it does not take into consideration the dialyzer clearance or patient's body size. The aims of the present study were to clarify the theoretical validity of HDP focusing on its association with solute concentration by computer simulation and to propose a new index of hemodialysis adequacy. Methods: We used compartment models and calculated the time course of urea and β2 microglobulin (β2MG) concentrations to determine the peak concentrations and time-Averaged concentrations at varying dialysis frequencies (n = 2-7 sessions/week) and durations of dialysis per session (t = 1 to 8 h dialysis sessions). Results: It was found that the peak concentrations of urea and β2MG were significantly correlated with the HDP. Based on this, we theoretically extracted the factor related to the peak concentration and defined the squared frequency-Kt/V (sf-Kt/V), as a new index for determining hemodialysis adequacy (sf-Kt/V = n 2 Kt/V; K, clearance; V, solute distribution volume; n, frequency; t, dialysis time); this index was well correlated with the peak concentrations of urea and β2MG, even when the values of K and V were changed. Conclusions: Since the sf-Kt/V is an index that reflects peak concentrations of urea and β2MG, which takes into account the dialysis frequency, session duration, dialyzer clearance, and the body weight of the patient, it will be a very useful tool for determining appropriate dialysis schedules and dialysis conditions for individual patients.