Volume 66, Pages S3-S24 (July 2004) Mechanisms determining the ratio of conductivity clearance to urea clearance  Frank A. Gotch, Froilan M. Panlilio, Rosemary A. Buyaki, Erjun X. Wang, Thomas I. Folden, Nathan W. Levin  Kidney International  Volume 66, Pages S3-S24 (July 2004) DOI: 10.1111/j.1523-1755.2004.00759.x Copyright © 2004 International Society of Nephrology Terms and Conditions

Figure 1 (A) A schematic depiction of the on-line clearance monitor.(B) Typical dialysate inlet and outlet conductivity profiles and a stable blood inlet profile. The three basic conductivity dialysance equations are shown. Kidney International 2004 66, S3-S24DOI: (10.1111/j.1523-1755.2004.00759.x) Copyright © 2004 International Society of Nephrology Terms and Conditions

Figure 2 The left upper and lower panels depict the effect of isolated access recirculation on effective conductivity dialysance.The right panels illustrate the effects of cardiopulmonary and salt loading with systemic recirculation on effective conductivity dialysance. Note that in each instance the effect is mediated by increase and decrease in the blood inlet conductivity and reduction of the diffusion gradient. Kidney International 2004 66, S3-S24DOI: (10.1111/j.1523-1755.2004.00759.x) Copyright © 2004 International Society of Nephrology Terms and Conditions

Figure 3 (A) The Na osmotic distribution volume flow rate is compared to plasma and total blood water flow rates and shown to be equal to the total blood water flow rate.(B) Shown are the changes in dialyzer blood inlet Na concentration (ΔCbiNa) observed with single step baseline/high and the asymmetric high/low profile. Kidney International 2004 66, S3-S24DOI: (10.1111/j.1523-1755.2004.00759.x) Copyright © 2004 International Society of Nephrology Terms and Conditions

Figure 4 (A) The correlation ofobsKecnto Keu1in 98 patients with inclusion of high levels of access recirculation induced by counter current dialyzer blood flow and access flow.(B) A Bland Altman analysis of obsKecnand Keu1data indicates no bias over a wide range of clearance. Kidney International 2004 66, S3-S24DOI: (10.1111/j.1523-1755.2004.00759.x) Copyright © 2004 International Society of Nephrology Terms and Conditions

Figure 5 (A) The mean ratios of each sequential Kecnmeasurement (Kecnt) to the first value (Kecno) are plotted as a function of test number.There is a highly linear decrease in the mean ratio to 0.92 by the end of dialysis. (B) The coefficient of variation (CV) of the means is plotted as function of test number. Note that the CV is only 3% to 4% for the first 3 values and increases to 6% to 7% for the last values late in dialysis. Kidney International 2004 66, S3-S24DOI: (10.1111/j.1523-1755.2004.00759.x) Copyright © 2004 International Society of Nephrology Terms and Conditions

Figure 6 The magnitude of Na flux into blood during baseline/high and high/low dialysate profile segments measured in vitro.Note that net flux is 4 times higher with the single step baseline/high segment compared to the high/low segment. Kidney International 2004 66, S3-S24DOI: (10.1111/j.1523-1755.2004.00759.x) Copyright © 2004 International Society of Nephrology Terms and Conditions

Figure 7 (A) Ratios of Kecn3/Kucalculated to express f(Rs)•f(Rcp)withf(Rac) = 1.0 and f(Rcp) = .96are shown as functions of ΔCsNaand 4 levels of ΔCdiNa.(B) Ratios for Kecn1/Kuwith f(Rcp) = 0 are shown as a function of percent Rac. Ratios for Kecn2/Kuwith f(Rac) = 0 are also depicted. See text for discussion. Kidney International 2004 66, S3-S24DOI: (10.1111/j.1523-1755.2004.00759.x) Copyright © 2004 International Society of Nephrology Terms and Conditions

Figure 8 An invitro system for study of relationships between dialysate conductivity profile, cardiopulmonary recirculation, and systemic salt loading. Kidney International 2004 66, S3-S24DOI: (10.1111/j.1523-1755.2004.00759.x) Copyright © 2004 International Society of Nephrology Terms and Conditions

Figure 9 (A) The isolated effect of f(Rs) on Kecn/Kuratios expressed in Na concentration units and (B) conductivity units.The data plotted comprise 2 values calculated from Figure 2, and Figure 8values calculated from analysis of literature data. The analyses show that the obsKecn/Kuratio is frequently lowered through the technical mechanism, consisting of recirculation of a change in systemic blood Na during measurement f(Rs). See text for discussion of these data. Kidney International 2004 66, S3-S24DOI: (10.1111/j.1523-1755.2004.00759.x) Copyright © 2004 International Society of Nephrology Terms and Conditions

Figure 10 Comparison of the ΔCndiprofiles reported by Di Filippo to those used for this study.Note that the Di Filippo profile segments are about 3 times longer and that the high and low conductivities are symmetrical around the baseline. Kidney International 2004 66, S3-S24DOI: (10.1111/j.1523-1755.2004.00759.x) Copyright © 2004 International Society of Nephrology Terms and Conditions

Figure 11 Solution of Equation A46 for Kecn2/Keu1ratios over a wide range of Qac/CO with CO = 5.0 L and two levels of Ku bracketing the data reported by Di Filippo[7]. See text for discussion of panels (A–D). Kidney International 2004 66, S3-S24DOI: (10.1111/j.1523-1755.2004.00759.x) Copyright © 2004 International Society of Nephrology Terms and Conditions