MO663THE UTILITY OF SMART SCALES TO MONITOR BODY COMPOSITION IN HEMODIALYSIS PATIENTS

Background and Aims Overhydration (OH) is an independent predictor of mortality on hemodialysis (HD). The gold standard to assess OH is BCM monitor from Fresenius®, however BCM is a hospital hold device limiting its use. New smart scales have emerged as household devices reporting daily body composition data. Objective To determine if Renpho ES-CS20M® could be useful on a 52 HD patient to estimate body composition data. Method 72 body composition assessments (BCA) during mid-week HD session were performed. Each BCA included: (1) Predialysis Renpho measurement, (2) Predialysis BCM monitor measurement, (3) Postdialysis Renpho measurement. To track the fluid balance during the HD session: (1) we recorded ultrafiltration, (2) food or fluid intake was not allowed, and (3) none of the HD patients urinated during the HD session. If any intravenous fluids were needed during the HD session, we subtracted them off from UF. Results Data from 52 HD patients were studied (age 58.8 ± 16.8 years, 56.9 % males, 14.7% diabetics), with a mean pre-HD weight of 70.0 ± 13. 4 Kg, overhydration of 1.7 ± 1.5 L and urea distribution volume of 31.7 ± 5.7 L. The mean ultrafiltration during HD session was -1.8 ± 0.9 L. Renpho estimated a Pre – HD hydration of 34.25 ± 6.02 Kg vs 33.4 ± 5.7 Kg by BCM, showing a good concordance between methods (ICC 0.788 [0.67-0.86], B -0.58, p <0.01). Renpho poorly estimated pre – HD lean tissue mass at 45.4 ± 6.9 Kg compared with 33.8 ± 8.0 Kg by BCM. Although Renpho was able to provide a moderate concordant estimation of fat tissue mass (33.8 ± 8.0 % with Renpho vs 34.7 ± 9.6%), the bias proportion was unacceptable. Post- HD hydration by Renpho was not able to reproduce the ultrafiltracion achieved during the HD session (pre-HD 34.25 ± 6.02 Kg vs post-HD 34.08 ± 6.00 Kg). Conclusion Renpho has a proportional bias estimating predialysis hydration compared with BCM monitor, but is not able to assess changes produced with ultrafiltration or other parameters of body composition (as lean or fat tissue mass). Although smart scales are unacurate to assess body composition on HD patients, they could be useful on the follow up of them changing the accuracy for frequency.

MO599COMPARISON OF TOTAL BODY WATER MEASURED BY BIOIMPEDANCE SPECTROSCOPY TO UREA DISTRIBUTION VOLUME ESTIMATED FROM UREA KINETIC MODELING IN HEMODIALYSIS PATIENTS

Background and Aims Monitoring of fluid, body composition and nutritional changes is important in clinical nephrology. The Body Composition Monitor (BCM; Fresenius Medical Care, Bad Homburg, Germany) measures whole-body bioimpedance and determines extracellular and intracellular resistance by using the Cole-model to estimate total body water (TBW-BCM) and its partition into extracellular and intracellular water. Both can then be used to define body composition and separate body weight into lean tissue mass, adipose tissue mass, and fluid overload. Urea kinetic modeling (UKM) allows the estimation of dialysis dose (double-pooled Kt/V), urea distribution volume (V-UKM) and dietary protein intake. We studied the bias between estimated V-UKM to anthropometric and measured TBW-BCM (Vant, TBW-BCM). Method Pre-hemodialysis (HD), electrodes for the BCM assessments were placed on the non-arteriovenous access arm and ipsilateral leg, respectively, with the patient in a supine position. Vant was calculated using the Watson equation. In addition to these assessments we entered the specified values from the most recent urea kinetic modeling (UKM) treatment into the online solute-solver calculator (http://ureakinetics.org). We chose a baseline ratio of modeled/anthropometric volume of 0.6 to 1.3 L to exclude values with data entry errors and/or UKM sampling errors. We calculated the post HD TBW-BCM by subtracting the intradialytic weight loss and adjusted these estimates by the differences in post HD weight between sessions to make both estimates comparable. We depicted the comparison between the estimated V-UKM versus the TBW-BCM in a scatter- and Bland-Altman (BA) plot (Figure). For the purpose of error investigation we studied the computed bias (V-UKM minus TBW-BCM) as a function of body mass index (BMI) and stray capacitance (td) in a BA plot. We then calculated the difference between Vant and V-UKM and illustrated the comparison in a scatter and BA plot. Results In a cross-sectional design, we studied 161 stable prevalent HD patients (61.3±14.7 years, 98 (60.9%) males, height of 167.5±10.7 cm) prior to their treatment. The regression plot showed slight agreement (R2= 0.69) and the Bland-Altman plot no systematic trends or proportional error in the main analysis (Figure 1a and b). Neither BMI or td explained bias and variance in the bias between both estimates. Vant and V-UKM plots showed agreement (R2 of 0.68) with a mean bias of -2.3±5.1 and no proportional error. Conclusion Both TBW-BCM and the V-UKM as the “bronze standard” of TBW estimation seemed to agree reasonably well. Neither body composition measurement or kinetic modeling approach showed any significant influence on the accuracy and precision of the estimate. According to BCM availability, estimated V-UKM or measured TBW-BCM could be used alternatively in practice to support clinical decision when pharmacokinetic considerations are concerned.

O10 Effect of hemodialysis dose (spKt/V) on survival in patients on maintenance hemodialysis since childhood – a retrospective analysis

BackgroundHemodialysis (HD) prescription significantly differs between pediatric and adult patients on maintenance HD, resulting in greater difference between prescribed and delivered HD dose.1,2 HD dose targets have formally not been evaluated for children, hence targets are mainly derived from adults (spKt/V >1.4; sp: single-pool model of urea distribution, K: urea clearance, t: duration of HD session, V: urea distribution volume). This analysis aimed to evaluate the relationship between delivered dialysis dose and survival in a large cohort of patients having started HD therapy in childhood.MethodsThis retrospective analysis included a cohort of patients < 30 years (y) on chronic HD treatment since childhood, having received thrice-weekly HD between 2004 and 2016 in outpatient DaVita dialysis centers. Survival while on HD (death from any cause) was investigated using Kaplan-Meier analysis stratified by age at start of HD (0–2, >2–6, >6–12, and >12–18 y), and three mean delivered dialysis dose levels (spKt/V < 1.4, 1.4–1.6, >1.6). Survival curves between subgroups were compared using the Log-rank test.Results1773 patients were included in the analysis, among n=34 having started HD at age of 0–2y, n=57 at >2–6y, n=244 at >6–12y, and n=1438 at >12–18y. Median follow-up on HD ranged between 1.5 (>2–6y) to 4.7 years (>6–12y) with maximal follow-up of 23 years. Death while on HD occurred in 1/34, 6/57, 26/244, and 101/1438 patients during recorded follow-up (p=0.075, n.s.). Patients with mean spKt/V < 1.4 had lower survival on HD than those with spKt/V >1.4–1.6 (p=0.019) and those with spKt/V >1.6 (p=0.035), with 10-year survival estimated to 75% (65.2–86.2%) versus 84.5% (78.5–90.9%) and 85.0% (80.8–89.5%), respectively.ConclusionsThis is the first study to report long term survival and its relationship with delivered HD dose in patients starting HD in childhood. Our results support targeting spKt/V(urea)>1.4 in children on chronic HD treatment.ReferencesGotta V, Marsenic O, Pfister M. Age- and weight-based differences in haemodialysis prescription and delivery in children, adolescents and young adults. Nephrol Dial Transplant 2018 Apr 18.Gotta V, Marsenic O, Pfister M. Understanding urea kinetic factors that enhance personalized hemodialysis prescription in children. ASAIO J 2019 Jan 14.Disclosure(s)M Pfister is a consultant at Quantitative Solutions a Certara Company. V Gotta has been supported for this project by the Research Fund for Junior Researchers, University of Basel, Switzerland. O Marsenic and A Atkinson declare no financial conflict of interest.

Calculating Standard Kt/V during Hemodialysis Based on Urea Mass Removed

Background/Aims: We derived a novel equation for calculating weekly urea standard Kt/V (stdKt/V) during hemodialysis (HD) based on urea mass removed, comparable to the approach during peritoneal dialysis. Methods: Theoretical consideration of urea mass balance during HD led to the following equation for stdKt/V, namely, stdKt/V = N × (URR + UFV/V), where N is the number of treatments per week, URR is urea reduction ratio per treatment, UFV is ultrafiltration volume per treatment, and V is postdialysis urea distribution volume. URR required corrections for postdialysis rebound and intradialytic urea generation. We compared the accuracy of this approach with previous equations for stdKt/V by numerical simulations using a 2-compartment model of urea kinetics for thrice-weekly and more frequent HD prescriptions. Results: The proposed equation based on urea mass removed predicted values of stdKt/V that are equivalent to those calculated by previous equations for stdKt/V. Conclusion: This work provides a novel approach for calculating stdKt/V during HD and strengthens the theoretical understanding of stdKt/V.

Association of Continuous-Equivalent Urea Clearances with Death Risk in Intermittent Hemodialysis

Background. Several reports describe favorable results from frequent hemodialysis, but due to the lack of unequivocal dose measures it is not clear whether the benefits are due to more efficient toxin removal or other factors. Methods. The associations with death risk of six continuous-equivalent urea clearance measures were compared in 57 conventional in-center hemodialysis treatment periods of 51 patients, together 114 patient years. The double pool dose measures were calculated with the Solute-Solver program and separately scaled to urea distribution volume or normalized with body surface area. Results. Mortality associated significantly with equivalent renal urea clearance (EKR) scaled to urea distribution volume (V) (p=0.033) and with EKR normalized with body surface area (BSA) (p=0.044) but not with V-scaled (p=0.059) nor BSA-normalized (p=0.183) standard clearance (stdK). Women had significantly higher normalized protein catabolic rate (nPCR), EKR/V, and stdK/V than men but slightly lower BSA-normalized dose measures and lower mortality. Protein catabolic rate and dialysis dose correlated positively with each other and with survival. Conclusions. The prognostically most valid continuous-equivalent clearance in the present material was EKR/V, calculated from double pool urea generation rate, distribution volume, and time-averaged concentration.

Volume-Based Peritoneal Dialysis Prescription Guide to Achieve Adequacy Targets

BackgroundThe use of automated and continuous ambulatory peritoneal dialysis (APD and CAPD) prescriptions (Rxs) to achieve adequate uremic toxin and fluid removal targets is important for attaining optimal patient outcomes. One approach for predicting such Rxs is the use of kinetic modeling.MethodsDemographic data and peritoneal membrane characteristics derived from a peritoneal equilibration test (PET) were available from 1,005 patients in North American centers who participated in a national adequacy initiative in 1999. Twelve patient subgroups were identified according to peritoneal membrane transport type and tertiles of total body water, assumed equal to urea distribution volume (Vurea). Each patient was then modeled using PD Adequest 2.0 to be treated by 12 CAPD and 34 APD Rxs using both glucose and icodextrin solutions to achieve adequacy targets of weekly urea Kt/V of 1.7 and 1 L of daily ultrafiltration (UF). Residual kidney function (RKF) was assumed to be 0, 2, 4, and 6 mL/min. Feasible peritoneal dialysis (PD) Rxs were identified where: 1) the 95% confidence limit achieved the goal of meeting the targets for urea Kt/V, daily UF, and both in 85%, 75%, and 70% of patients, respectively; 2) average PD solution dextrose concentration was < 2.5%; and 3) the number of daytime exchanges was minimized.ResultsFeasible PD Rxs were similar when RKF was ≥ 2 mL/min, allowing condensed recommendations based on RKF ≥ 2 mL/min or < 2 mL/min. Individuals with lower or slower membrane transport required relatively greater 24-h solution volumes to achieve adequacy targets when RKF fell below 2 mL/min. With increasing Vurea, there was disproportionately greater dependence on RKF to achieve targets. While multiple Rxs achieving urea Kt/V and daily UF goals were identified for all membrane transport types, use of icodextrin in the long dwell reduced the need for a midday exchange in APD, glucose exposure, required fill and 24-h dwell volumes, irrespective of RKF and Vurea. While these benefits were most notable in high and high-average transporters, similar results were also seen in low and low-average transporters.ConclusionsKinetic modeling identified multiple APD and CAPD Rxs that achieved adequate uremic solute and fluid removal for patients, irrespective of RKF and Vurea. Use of icodextrin rather than glucose in the long dwell reduced the complexity of the PD regimen, total glucose exposure, and 24-h total treatment solution volumes. Irrespective of modeling, adequacy of any PD prescription should be based upon individual clinical evaluation both for volume and solute removal.

Urea Concentration and Haemodialysis Dose

Background. Dialysis dose is commonly defined as a clearance scaled to some measure of body size, but the toxicity of uraemic solutes is probably associated more to their concentrations than to their clearance. Methods. 619 dialysis sessions of 35 patients were modified by computer simulations targeting a constant urea clearance or a constant urea concentration. Results. Urea generation rate G varied widely in dialysis patients, rather independently of body size. Dialysing to eKt/V 1.2 in an unselected patient population resulted in great variations in time-averaged concentration (TAC) and average predialysis concentration (PAC) of urea (5.9–40.2 and 8.6–55.8 mmol/L, resp.). Dialysing to equal clearance targets scaled to urea distribution volume resulted in higher concentrations in women. Dialysing to the mean HEMO-equivalent TAC or PAC (17.7 and 25.4 mmol/L) required extremely short or long treatment times in about half of the sessions. Conclusions. The relation between G and V varies greatly and seems to be different in women and men. Dialysing to a constant urea concentration may result in unexpected concentrations of other uraemic toxins and is not recommended, but high concentrations may justify increasing the dose despite adequate eKt/V, std EKR, or std K/V.