Determination of Dialysis Dose: A Clinical Comparison of Methods

Abstract

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.

Ionic Dialysance and Determination of Kt/V in on-line Hemodiafiltration with Simultaneous Pre- and Post-dilution

“…The correlation coefficient (0.72) can be accepted as good when considering two fully independent methods. Moreover, this value is in agreement with the value reported by Ahrenholz et al (r = 0.74) (24).…”

Quantification of Hemodialysis Dose: What Kt/V to Choose?

“…Measuring the dialysis dose automatically in every dialysis treatment enables early countermeasures in order to maintain the recommended level of dialysis dose (35). Even for a high delivered dialysis dose, an unexpected decrease of the dialysis dose may indicate for problems with the treatment procedure itself (e.g., delivered blood flow rate lower than displayed by the monitor, or beginning clotting in dialyzer) or for problems with blood access (e.g., decreasing shunt flow due to developing stenosis) (36).…”

“…An automatic measurement of the dialysis dose during every dialysis session does no harm to the patient, as no blood samples are taken. For patients with a constant dialysis dose >1.6 the benefit of an automatic measurement may be moderate, but for patients with varying and lower dialysis doses, the risk of an undetected low dialysis dose for longer periods of time are real, and the benefit of continuous surveillance concerning dose delivery seems obvious (36). The OCM is a practical method for measuring dialysis dose semi-continuously during dialysis session using conductivity monitoring.…”

Hemodialysis patients receiving a greater Kt dose than recommended have reduced mortality and hospitalization risk

“…This system measures the effective in vivo urea clearance (K) and calculates the accumulated Kt. 35 The Fresenius machine time setting to adjust the frequency of Kt measurements was 30 minutes in all dialysis units. The target Kt was calculated monthly for each patient using the following algebraic expression: minimum target Kt in liters ¼ 1/ [0.0069 þ (0.0237/BSA)], with BSA in m 2 ¼ weight 0.425 Â height 0.725 Â 0.007184, with weight (post-dialysis dry body weight) expressed as kilograms and height measured in centimeters.…”