Determination of dialysis dose: a clinical comparison of methods.

Background: Guidelines recommend regular measurements of the delivered hemodialysis dose Kt/V. Nowadays, automatic non-invasive online measurements are available as alternatives to the conventional method with blood sampling, laboratory analysis, and calculation. Methods: In a prospective clinical trial, three different methods determining dialysis dose were simultaneously applied: Kt/V-Dau (conventional method with Daugirdas' formula), Kt/V-OCM [online clearance measurement (OCM) with urea distribution volume V based on anthropometric estimate], and Kt/V-BCM [OCM measurement with V measured by bioimpedance analysis (Body Composition Monitor)]. Results: 1,076 hemodialysis patients were analyzed. The dialysis dose was measured as Kt/V-Dau = 1.74 +/- 0.45, Kt/V-OCM = 1.47 +/- 0.34, and Kt/V-BCM = 1.65 +/- 0.42. The difference between Kt/V-OCM and Kt/V-BCM was due to the difference between anthropometric estimated V-Watson and measured V-BCM. Compared to Kt/V-Dau, Kt/V-OCM was 15% lower and Kt/V-BCM 5% lower. Kt/V-Dau was incidentally prone to falsely high values due to operative errors, whereas in these cases OCM-based measurements Kt/V-OCM and Kt/V-BCM delivered realistic values. Conclusions: The automated OCM Kt/V-OCM with anthropometric estimation of urea distribution volume was the easiest method to use, but Kt/V-BCM with measured urea distribution volume was closer to the conventional method. Copyright (C) 2011 S. Karger AG, Basel