Effect of treatment frequency on haemodialysis dose: comparison of EKR and stdKt/V.

BACKGROUND Haemodialysis outcome cannot be improved by increasing the dialysis session dose above the current standard in conventional schedules. Promising results have been reported from daily dialysis, but the optimal dose has not been established. METHODS Weekly eKt/V, equivalent renal clearance (EKR) and stdKt/V were compared retrospectively in 588 complete urea kinetic modelling sessions of 35 haemodialysis patients. Equivalent values of EKR and stdKt/V corresponding to the standard and high doses of the HEMO study were defined by computer simulation. The effect of frequency on the dose measures was demonstrated by simulating different schedules. RESULTS EKR and stdKt/V take into consideration both frequency and RRF, but appreciate them differently. The values of EKRc (EKR in millilitres per minute, normalized to distribution volume 40 l), stdEKR (EKR in litres per week divided by urea distribution volume in litres) and stdKt/V corresponding to eKt/V 1.20-close to the standard dose in the HEMO study-were 13.2 ml/min/40 l, 3.34/wk and 2.23/wk, respectively. stdKt/V appreciates frequency more than EKR. A spreadsheet was created to compute the dialysis session time to achieve the EKR or stdKt/V target when the basic urea kinetic variables are known. CONCLUSIONS Haemodialysis efficiency can be increased by increasing frequency. EKR and stdKt/V are more appropriate than weekly eKt/V as measures of dialysis dose in different schedules. With increasing frequency, stdKt/V as the dosing target results in shorter treatment times and higher concentrations than EKR.