Several methods exist to quantitate small-solute clearance by daily hemodialysis (HD) regimens, but these have not been empirically applied or compared.
In the London Daily/Nocturnal Hemodialysis Study, dosing and adequacy of quotidian HD regimens, both short daily HD (n = 11) and long nocturnal HD (n = 12), were compared with conventional thrice-weekly HD (n = 22) using several models. Urea clearance was computed by percentage of reduction in urea, kinetic modeling (single-pool Kt/V [spKt/V]), Daugirdas rate equation (equilibrated Kt/V [eKt/V]), and Gotch standardized Kt/V (stdKt/V).
Nocturnal HD patients maintained a mean single-session spKt/V of 1.64 throughout the study, similar to that of conventional HD patients (1.73), whereas daily HD patients showed a significant decrease in mean single-session spKt/V (0.93) compared with baseline (t(0)) values. Mean weekly spKt/V values increased from t(0) for both quotidian HD groups (9.08 for nocturnal HD, 5.55 for daily HD) and were higher in both quotidian HD groups compared with conventional HD patients. Weekly eKt/V, stdKt/V, and normalized protein equivalent of nitrogen appearance values showed similar trends. Comparison of the 3 different adequacy models showed an increase in weekly HD doses for both quotidian HD regimens compared with conventional HD; however, percentages of increases from t(0) to follow-up differed according to the model used. The calculated efficiency of dose delivery at the 10-month follow-up comparing daily HD with conventional HD was 257 +/- 26 minutes versus 306 +/- 17 stdKt/V unit delivered, respectively, amounting to almost 1 dialysis-hour saved per stdKt/V unit delivered for daily HD.
These results show that both quotidian HD regimens are more effective than conventional HD in improving weekly urea clearance measured by spKt/V, stdKt/V, and eKt/V.