Clinical outcomes of hemodialysis patients in a public-private partnership care framework in Italy: a retrospective cohort study.

BACKGROUND: Innovative care models such as public-private partnerships (PPPs) may help meet the challenge of providing cost-effective high-quality care for the steadily growing and complex chronic kidney disease population since they combine the expertise and efficiency of a specialized dialysis provider with the population care approach of a public entity. We report the five-years main clinical outcomes of a population of patients treated on hemodialysis within a PPP-care model in Italy. METHODS: This descriptive retrospective cohort study consisted of all consecutive hemodialysis patients treated in the NephroCare-operated Nephrology and Dialysis unit of the Seriate Hospital in 2012-2016, which exercises a PPP-care model. Clinical and treatment information was obtained from the European Clinical Database. Hospitalization outcomes and cumulative all-cause mortality incidences that accounted for competing risks were calculated. RESULTS: We included 401 hemodialysis patients (197 prevalent and 204 incident patients) in our study. The mean cohort age and age-adjusted Charlson Comorbidity Index were 67.0 years and 6.7, respectively. Patients were treated with online high-volume hemodiafiltration or high-flux hemodialysis. Parameters of treatment efficiency were above the recommended targets throughout the study period. Patients in the PPP experienced benefits in terms of hospitalization (average number of hospital admissions/patient-year: 0.79 and 1.13 for prevalent and incident patients, respectively; average length of hospitalization: 8.9 days for both groups) and had low cumulative all-cause mortality rates (12 months: 10.6 and 7.8%, 5 years: 42.0 and 35.9%, for prevalent and incident patients, respectively). CONCLUSIONS: Results of our descriptive study suggest that hemodialysis patients treated within a PPP-care model framework received care complying with recommended treatment targets and may benefit in terms of hospitalization and mortality outcomes.

Partition of Omega-like facility into two configurations of 24 and 36 laser beams to improve implosion performance.

An Omega-like beam configuration is considered where the 60-beam layout can be separated into two independent sub-configurations with 24 and 36 laser beams, each minimizing direct drive illumination non-uniformity. Two different laser focal spot profiles, one associated with each configuration, are proposed to apply the zooming technique in order to increase the laser-target coupling efficiency. This approach is used by 1D hydrodynamics simulations of the implosion of a direct-drive capsule characterized by a relatively large aspect ratio A = 7 and an optimized laser pulse shape delivering a maximum of 30 TW and 30 kJ, with different temporal pulse shapes in each of the two sets of beams. It is shown that zooming allows for an optimistic 1D thermonuclear energy gain greater than one while without zooming the thermonuclear gain remains largely below one. While this is incompatible with the as-built Omega laser, it provides a promising option for a future intermediate-energy direct drive laser system.

High-Target Hemodiafiltration Convective Dose Achieved in Most Patients in a 6-Month Intermediary Analysis of the CONVINCE Randomized Controlled Trial.

Introduction: High convection volumes in hemodiafiltration (HDF) result in improved survival; however, it remains unclear whether it is achievable in all patients. Methods: CONVINCE, a randomized controlled trial, randomized patients with end-stage kidney disease 1:1 to high-dose HDF versus high-flux hemodialysis (HD) continuation. We evaluated the proportion of patients achieving high-dose HDF target: convection volume per visit of ≥23 l (range ±1 l) at baseline, month 3, and month 6. We compared baseline characteristics in the following 2 ways: (i) patients on target for all 3 visits versus patients who missed target on ≥1 visits and (ii) patients on target for all 3 visits or missing it once versus patients who missed target on ≥2 visits. Results: A total of 653 patients were randomized to HDF. Their mean age was 62.2 (SD 13.5) years, 36% were female, 81% had fistula vascular access, and 33% had diabetes. Across the 3 visits, 75 patients (11%), 27 patients (4%), and 11 patients (2%) missed the convection volume target once, twice, and thrice, respectively. Apart from diabetes, there were no apparent differences in patient characteristics between patients who always achieved the high-dose target (83%) and those who missed the target either once or more (17%) or twice or more (6%). Conclusion: Achieving high-dose HDF is feasible for nearly all patients in CONVINCE and could be maintained during the 6-month follow-up period. Apart from diabetes, there were no other indications for confounding by indication on multivariable analyses that may explain the potential survival advantage for patients receiving high-dose HDF.

Effect of collisions with a second fluid on the temporal development of nonlinear, single-mode, Rayleigh-Taylor instability.

Goncharov's [Phys. Rev. Lett. 88, 134502 (2002)0031-900710.1103/PhysRevLett.88.134502] nonlinear model of a single-mode Rayleigh-Taylor instability (RTI) is investigated for a partially ionized plasma in a predominantly neutral background. Terminal bubble and spike velocities are derived from the nonlinear equations in the case where the RTI dynamics is dominated by collisions between neutrals and ions. Direct numerical simulations are used to justify the use of Goncharov's model in this regime and observe its limitations.

Change in inertial confinement fusion implosions upon using an ab initio multiphase DT equation of state.

Improving the description of the equation of state (EOS) of deuterium-tritium (DT) has recently been shown to change significantly the gain of an inertial confinement fusion target [S. X. Hu et al., Phys. Rev. Lett. 104, 235003 (2010)]. Here we use an advanced multiphase EOS, based on ab initio calculations, to perform a full optimization of the laser pulse shape with hydrodynamic simulations starting from 19 K in DT ice. The thermonuclear gain is shown to be a robust estimate over possible uncertainties of the EOS. Two different target designs are discussed, for shock ignition and self-ignition. In the first case, the areal density and thermonuclear energy can be recovered by slightly increasing the laser energy. In the second case, a lower in-flight adiabat is needed, leading to a significant delay (3 ns) in the shock timing of the implosion.

Fewer dose changes with once-monthly C.E.R.A. in patients with chronic kidney disease.

BACKGROUND: Frequent dosing and requirements for dose adjustments of erythropoiesis-stimulating agents (ESAs) create significant burdens for healthcare providers and have been associated with hemoglobin (Hb) cycling, hampering maintenance of target Hb levels. We compared the frequency of dose changes in dialysis patients who received methoxy polyethylene glycolepoetin beta; (a continuous erythropoietin receptor activator (C.E.R.A.)) or a shorter-acting ESA. METHODS: Data were analyzed from three Phase III maintenance trials, using almost identical protocols, in dialysis patients treated with C.E.R.A. every 2 weeks (q2w) or every 4 weeks (q4w) or a comparator ESA (epoetin or darbepoetin alpha; at their previous dose/administration interval). Dosage was adjusted to maintain Hb ± 1 g/dl of baseline and 10 - 13.5 g/dl during titration (28 weeks) and evaluation (8 weeks), and 11 - 13 g/dl during follow-up (16 weeks). RESULTS: Data were analyzed from 564 patients treated with C.E.R.A. q2w, 410 with C.E.R.A. q4w and 572 with comparator ESA at their usual dosing interval. Significantly fewer dose changes were needed in patients receiving C.E.R.A. q2w (p < 0.05) or C.E.R.A. q4w (p < 0.001) than in patients treated with comparator ESAs. CONCLUSION: This retrospective analysis suggests that C.E.R.A. q4w maintains Hb levels in dialysis patients and requires fewer dose changes compared with other ESAs.

[Carbonyl stress and oxidatively modified proteins in chronic renal failure]. / Stress carbonylé et modifications oxydatives des protéines au cours de l'insuffisance rénale chronique.

Oxidative stress is commonly observed in chronic renal failure patients resulting from an unbalance between overproduction of reactive oxygen species and impairement of defense mechanisms. Proteins appear as potential targets of uremia-induced oxidative stress and may undergo qualitative modifications. Proteins could be directly modified by reactive oxygen species which leads to amino acid oxydation and cross-linking. Proteins could be indirectly modified by reactive carbonyl compounds produced by glycoxidation and lipo-peroxidation. The resulting post-traductional modifications are known as carbonyl stress. In addition, thiols could be oxidized or could react with homocystein leading to homocysteinylation. Finally, tyrosin could be oxidized by myeloperoxidase leading to advanced oxidative protein products (AOPP). Oxidatively modified proteins are increased in chronic renal failure patients and may contribute to exacerbate the oxidative stress/inflammation syndrome. They have been involved in long term complications of uremia such as amyloidosis and accelerated atherosclerosis.

[Physical principles of renal replacement therapy applied to end stage renal disease patients]. / Principes et modalités d'application de l'hémodialyse au traitement de l'insuffisance rénale chronique.

"Hemodialysis" is the generic term that refers to all forms of renal replacement therapy (RRT) able to restore periodically the "internal milieu" composition in end stage renal disease patients (ESRD). RRT includes several modalities (hemodialysis, hemofiltration, hemodiafiltration) that induce basic physical principles (diffusion, convection, adsorption) via an exchange module (dialyser) and an electrolytic exchange solution (dialysis fluid). The cleansing property of the RRT depends on different factors: the treatment modality itself, the uremic toxin considered, patient's characteristic and the operational conditions (duration of treatment, session frequency, blood and dialysate flow rates). Solute instantaneous clearances reflect the dialyser's performances used in optimal conditions but not necessarily the body clearance. The effective solute body clearance is more difficult to assess in clinical practice since it includes some variables such as the treatment duration, the biological complexity of internal milieu and the variability of the patient/dialysis system interaction. The "dialysis adequacy" concept that governs the treatment efficacy in ESRD patients could not be reduced to the urea Kt/V ratio. It must integrate a selection of pertinent clinical and biological markers covering the complete spectrum of uremic abnormalities. Adequate knowledge of those basic physical principles that control the solute exchange in hemodialysis patient is highly recommended to any nephrologist who looks forward to improve treatment efficacy and reduce mortality in ESRD patients.

CVD diamond detector with interdigitated electrode pattern for time-of-flight energy-loss measurements of low-energy ion bunches.

Ion stopping experiments in plasma for beam energies of few hundred keV per nucleon are of great interest to benchmark the stopping-power models in the context of inertial confinement fusion and high-energy-density physics research. For this purpose, a specific ion detector on chemical-vapor-deposition diamond basis has been developed for precise time-of-flight measurements of the ion energy loss. The electrode structure is interdigitated for maximizing its sensitivity to low-energy ions, and it has a finger width of 100 µm and a spacing of 500 µm. A short single α-particle response is obtained, with signals as narrow as 700 ps at full width at half maximum. The detector has been tested with α-particle bunches at a 500 keV per nucleon energy, showing an excellent time-of-flight resolution down to 20 ps. In this way, beam energy resolutions from 0.4 keV to a few keV have been obtained in an experimental configuration using a 100 µg/cm2 thick carbon foil as an energy-loss target and a 2 m time-of-flight distance. This allows a highly precise beam energy measurement of δE/E ≈ 0.04%-0.2% and a resolution on the energy loss of 0.6%-2.5% for a fine testing of stopping-power models.

[Sodium determination in biological fluids]. / Méthodes de dosage du sodium dans les liquides biologiques.

Electrolyte disorders are frequently observed in nephrology and intensive care unit department and Na determination is routinely performed in biochemistry laboratories. Three methods are currently available. Flame photometry remains the reference method. With this method the serum sample is diluted before the actual measurement is obtained. Results are expressed as molarity (per Liter of plasma). Potentiometric methods have an increasing importance due to the advances in ion sensitive (selective) electrodes (ISE). Whereas the instruments for routine chemical analysis typically use indirect potentiometry (involving te dilution of samples) to measure sodium levels, the equipment for measuring arterial blood gases use direct potentiometry without any dilution. Thus, results obtained with indirect potentiometry are expressed in molarity (per liter of plasma) while results obtained with direct potentiometry are initially given in morality (per kg of plasma water) then converted in molarity. Analytical performances are in all cases satisfactory and therefore all the methods could be used in both normal and pathological ranges. Methods involving sample dilution such as flame photometry or indirect potentiometry, the serum sodium value would be expected to be low in case of decrease plasma water (pseudohyponatremia). By contrast, with direct potentiometry where no sample dilution takes place, no interference would be expected since the activity of sodium in the water phase only is being measured. Thus, the classical pseudohyponatremia observed with hyperlipemia or paraproteinemia are not further observed with direct potentiometry. These differences in methodology should be taken into account to explain discrepancies between results obtained with classical biochemistry analyser and with blood gas apparatus.

[Residual renal function in dialysis patients]. / Rôle de la fonction rénale résiduelle dans la balance sodée du dialysé: est-ce un bénéfice ou un risque?

Residual renal function (RRF) contributes to the achievement of treatment adequacy in CKD-5 patients. It may facilitate patients' acceptance of renal replacement therapy (RRT) in minimizing dietary and fluid restriction. It has been confirmed to improve dialysis patient outcomes. Attempts to preserve RKF in incident CKD-5 patients are still subject to controversies. In this review we analyze the role of RRT in dialysis patient. What are the positive and the beneficial effects of maintaining RRF? What are the negative and the risks of maintaining a RRF? At what expense the maintenance of RRF is achieved? Preservation of RRF is undoubtedly an interesting means to enhance the efficacy of renal replacement therapy and reduce dietary fluid restriction. However, maintainance of RRF should not be considered as a goal of dialysis adequacy in dialysis patients but rather a means of optimizing RRT. Further, preservation of RRF should be considered as a permanent trade-off between patient comfort and chronic fluid volume overload with its deleterious effects.

The role of mineral metabolism and inflammation on dialysis vascular access failure.

Thrombosis of arteriovenous fistula (AVF) is the leading cause of vascular access (VA) loss usually due to silent stenosis. Therefore, assessment of relevant risk factors of VA monitoring may provide insight into potential therapeutic targets for stenosis and thrombosis. The aim of this study was to evaluate the influence of cardiovascular risk factors (including inflammation and mineral metabolism dysfunctions) on the failure of internal AVF in HD patients. 128 HD patients with internal AVF were included in the study and followed up for two years. At baseline, VA morphology and function were followed by Doppler ultrasonography and serum albumin, prealbumine, C-reactive protein, orosomucoid, calcium, phosphorus, parathyroid hormone, bone-type alkaline phosphatase, osteoprotegerin and receptor activator of nuclear factor ê ê B ligand were measured. At baseline, 50 stenoses were detected but none of them required any intervention. Age and biological parameters did not significantly differ between patients with or without VA stenosis. Over the two year- follow up, VA thrombosis occurred in 19 patients. Preexisting stenosis of VA was present in 9/19 patients (47.3% of cases) (chi-square = 3.708, p = 0.0538). Despite the low rate of events, phosphorus [1.75 (0.95-2.77) vs 1.42 (0.47-3.22) mmol/L, p = 0.0416], Calcium x Phosphorus product [4.00 (2.00-5.90) vs 3.40 (1.10-6.80) mmol(2)/L(2), p = 0.0676] and parathyroid hormone [165.00 (1.00-944.00) vs 79.50 (1.00-846.60) ng/L, p = 0.0814) levels were higher in the 19 thrombotic patients whereas all other biological parameters did not significantly differ. These results, which confirm that VA thrombosis occurs more frequently upon preexisting stenosis, also demonstrate that mineral metabolism disorders, compared to inflammation, may contribute to VA dysfunction leading to thrombosis.

Unraveling the relationship between mortality, hyponatremia, inflammation and malnutrition in hemodialysis patients: results from the international MONDO initiative.

BACKGROUND/OBJECTIVES: Hyponatremia is a risk factor for mortality in hemodialysis (HD) patients. It is not well known to which extent the comorbidities, malnutrition, fluid status imbalance and inflammation are related to hyponatremia and affect outcomes. SUBJECTS/METHODS: We studied 8883 patients from the European subset of the international MONitoring Dialysis Outcomes initiative. Nutritional and fluid statuses were assessed by bioimpedance spectroscopy. Fluid depletion was defined as overhydration⩽-1.1 l and fluid overload as overhydration>+1.1 l, respectively. Malnutrition was defined as a lean tissue index below the 10th percentile of age- and gender-matched healthy controls. Hyponatremia and inflammation were defined as serum sodium levels <135 mEq/l and C-reactive protein levels>6.0 mg/l, respectively. We used logistic regression to test for predictors of hyponatremia and Cox proportional hazards analysis to assess the association with all-cause mortality. RESULTS: Hyponatremia was predicted by the presence of malnutrition (odds ratio (OR)=1.49 (95% confidence interval (CI)=1.30-1.70), inflammation (OR=1.44 (95% CI=1.26-1.64)) and fluid overload ((>+1.1 l to +2.5 l) OR=0.73 (95% CI=0.62-0.85)) but not by fluid depletion (OR=1.34 (95% CI=0.92-1.96)). Malnutrition, inflammation, fluid overload, fluid depletion and hyponatremia (hazard ratio=1.70 (95% CI=1.46-1.99)) were independent predictors for all-cause mortality. CONCLUSIONS: In HD patients, hyponatremia is associated with malnutrition, inflammation and fluid overload. Hyponatremia maintained predictive for all-cause mortality after adjustment for malnutrition, inflammation and fluid status abnormalities. The presence of hyponatremia may assist in identifying HD patients at increased risk of death.

Association between pre hemodialysis serum sodium concentration and blood pressure: results from a retrospective analysis from the international monitoring dialysis outcomes (MONDO) initiative.

A recent study from the United Kingdom indicates an association between pre hemodialysis (HD) serum sodium (SNa(+)) and systolic and diastolic blood pressure (SBP and DBP) in chronic HD patients. We extend this analysis to an international cohort of incident HD patients. The Monitoring Dialysis Outcomes initiative encompasses patients from 41 countries. Over 2 years monthly pre-HD SNa(+) levels were used as predictors of pre-HD SBP and DBP in a linear mixed model (LMM) adjusted for age, gender, interdialytic weight gain, diabetes, serum albumin and calcium. Similar models were constructed with DBP as outcome. Analyses were carried out stratified by continent (North and South America; Europe and Asia). LMMs were also constructed for the entire observation period of 2 years, and separately the first and the second year after HD initiation. We studied 17 050 incident patients and found SNa(+) to have a significant slope estimate in the LMM predicting pre-HD SBP and DBP (ranging from 0.22 to 0.29 and 0.10 to 0.21 mm Hg per mEq l(-1), respectively, between the continents). The findings were similar in subsets of SBP and SNa(+) tertiles, and separately analyzed for the first and second year. Our analysis shows an independent association between SNa, SBP and DBP in a large intercontinental database, indicating that this relation is a profound biological phenomenon in incident and prevalent HD patients, generalizable to an international level and independent of SBP and DBP magnitude.

Cumulative iron dose and resistance to erythropoietin.

INTRODUCTION: Optimizing anemia treatment in hemodialysis (HD) patients remains a priority worldwide as it has significant health and financial implications. Our aim was to evaluate in a large cohort of chronic HD patients in Fresenius Medical Care centers in Spain the value of cumulative iron (Fe) dose monitoring for the management of iron therapy in erythropoiesis-stimulating agent (ESA)-treated patients, and the relationship between cumulative iron dose and risk of hospitalization. METHODS: Demographic, clinical and laboratory parameters from EuCliD(®) (European Clinical Dialysis Database) on 3,591 patients were recorded including ESA dose (UI/kg/week), erythropoietin resistance index (ERI) [U.I weekly/kg/gr hemoglobin (Hb)] and hospitalizations. Moreover the cumulative Fe dose (mg/kg of bodyweight) administered over the last 2 years was calculated. Univariate and multivariate analyses were performed to identify the main predictors of ESA resistance and risk of hospitalization. Patients belonging to the 4th quartile of ERI were defined as hypo-responders. RESULTS: The 2-year iron cumulative dose was significantly higher in the 4th quartile of ERI. In hypo-responders, 2-year cumulative iron dose was the only iron marker associated with ESA resistance. At case-mix adjusted multivariate analysis, 2-year iron cumulative dose was an independent predictor of hospitalization risk. DISCUSSION: In ESA-treated patients cumulative Fe dose could be a useful tool to monitor the appropriateness of Fe therapy and to prevent iron overload. To establish whether the associations between cumulative iron dose, ERI and hospitalization risk are causal or attributable to selection bias by indication, clinical trials are necessary.

Evaluation of high-flux hemodiafiltration efficiency using an on-line urea monitor.

On-line urea monitoring of the effluent dialysate offers a real-time assessment of dialysis efficiency and metabolic/nutritional characteristics of hemodialysis patients. Quantitative parameters were evaluated by dialysate urea kinetic modeling (DUKM) with an on-line urea sensor in 23 patients treated by high-flux hemodiafiltration (HDF) (215 sessions of 210 to 240 minutes with a mean blood flow rate of 367 +/- 44 mL/min). Overall, the mean effective Kt/V was 1.52 +/- 0.29, the urea mass removed (22.8 +/- 5.5 g/session or 814 +/- 198 mmol/session), the solute removal index (SRI) 73% +/- 6.1%, and the mean normalized protein catabolic rate (nPCR), 1.15 +/- 0.31 g/kg/day. Blood urea kinetic modeling (BUKM), based on pre- and postsession urea concentrations, using equations from Daugirdas and Garred to calculate equilibrated Kt/V and nPCR, respectively, were in good agreement with DUKM, the differences observed appearing not clinically relevant. The variability of evaluated parameters was verified over consecutive sessions for a mean period of 3 weeks in the entire group. Mean variation in Kt/V was 8%; in urea mass removal, 18%; and in nPCR, 18%. When assessed over 1 week in a subgroup of 13 patients, Kt/V and PCR remained relatively stable, and urea mass removal per- and postsession declined from 23.5 +/- 8.0 g (840 +/- 285 mmol) to 18.7 +/- 6.3 g (667 +/- 225 mmol) from the first to the third session of the week, most likely as a consequence of interdialytic intervals. Predialysis urea concentrations followed the same trend. In the current study, DUKM with on-line urea sensor has confirmed that HDF is a highly efficient renal replacement modality; the variability observed in quantitative parameters supports a need for frequent adequacy monitoring. On-line urea monitoring of effluent dialysate is a simple device that provides the opportunity to tailor treatment to patient needs.

Effective blood flow and recirculation rates in internal jugular vein twin catheters: measurement by ultrasound velocity dilution.

The ultrasound dilution technology (Transonic Systems, Ithaca, NY) is a reliable method to assess blood flow (Qb) and recirculation rates (R) in vascular access during hemodialysis. However, the information available on these parameters for central venous dialysis catheters remains scarce at this point. Real Qb and R were evaluated in 33 well-functioning TwinCath (Medcomp, Harleysville, PA) inserted as mid- or long-term hemodialysis vascular access (mean duration since insertion, 270 +/- 253 days); all were implanted into the right internal jugular vein with their multiperforated distal tips located in the superior vena cava or right atrium. Several types of dialysis machines were used (Monitral and AK100, Hospal-Gambro, Lyon, France; 2008E and 4008E, Fresenius, Bad Homburg, Germany). Real Qb was measured with the ultrasound dilution method and compared with the set Qb (indicated by the dialysis machine); R, also evaluated by ultrasound dilution, was evaluated at various Qb with nonreversed lines; therefore, a total of 121 measures were performed. Arterial and venous pressures (PA and PV) were recorded simultaneously. The 33 measures at a set Qb of 200 mL/min showed a mean effective Qb of 210 +/- 18 mL/min and a mean R of 5.3 +/- 5.3%. At a Qb of 300 mL/min, 33 repeated measures resulted in mean effective Qb of 303 +/- 21 mL/min and R of 8.5 +/- 7.0%; 28 measures performed at a set Qb of 350 mL/min showed that the effective Qb was 336 +/- 24 mL/min and that R was 7.8% +/- 6.7%. Finally, an effective Qb of 372 +/- 26 mL/min and an R of 10.9 +/- 8.6% were found for the 27 measures performed at an indicated Qb of 400 mL/min. The difference between indicated and effective Qb was particularly significant for set Qb equal to or above 350 mL/min (P < 0.001). Variable correlations were observed between obtained parameters: Qb eff and R (r = 0.34), PV and R (r = 0.36), Qb eff and PV (r = 0.78), Qb eff and PA (r = 0.71), and PV and PA (r = 0.53). In conclusion, TwinCath delivers an effective Qb of nearly 375 mL/min when Qb is set at 400 mL/min on most dialysis machines. Mean R in TwinCath varies between 5% and 11% for Qb within the range of 200 to 400 mL/min. In well-functioning TwinCath, the ratio between PV and Qb remains usually below 0.5.

Influence of nutritional factors and hemodialysis adequacy on the survival of 1,610 French patients.

Nutritional factors and dialysis adequacy are associated with outcome in hemodialyzed patients, but their relative contribution remains controversial, particularly when dialysis adequacy complies with current recommendations (Kt/V >1.2). Survival, clinical, and nutritional data from a cohort of prevalent 1,610 patients treated by hemodialysis in 20 centers in France have been collected over a 2.5-year period, from January 1996 to July 1998. Data including age, sex, cause of end-stage renal disease (ESRD), clinical outcome, time on dialysis, body mass index (BMI), blood levels of midweek predialysis albumin, prealbumin, and bicarbonate were analyzed. Normalized protein catabolic rate (nPCR), dialysis adequacy parameters, and estimation of lean body mass (LBM) from creatinine generation were computed from pre- and postdialysis urea and creatinine levels. The characteristics of the patients were as follows: age 59.6 +/- 16.5 years, 58.8% males, 11% of diabetics, time on dialysis 63.2 +/- 64.5 m. Weekly dialysis time was 12.18 +/- 1.78 hrs, Kt/V 1.34 +/- 0.34, nPCR 1.10 +/- 0.35 g/kg body weight/day. Albumin concentration was 39.4 +/- 5.3 g/L, prealbumin was 0.33 +/- 0.09 g/L, BMI was 23.0 +/- 4.5 kg/m(2). Overall survival was 89.7% +/- 0.8% and 78.4% +/- 1.1% after 1 and 2 years. In the Cox proportional hazard model, survival was significantly influenced by age, the presence of diabetes, and by concentrations of albumin and prealbumin, but not by other variables, including Kt/V and urea reduction ratio. These results indicate that nutritional protein concentrations were predictive of dialysis outcome, whereas variables reflecting actual body composition and dialysis dose were not. Furthermore, in this well-dialyzed population, dialysis adequacy had no influence on survival. In conclusion, when adequacy targets are met in hemodialyzed patients, survival is mainly dependent on age and nutritional status. Efforts should be focused on the most efficient ways to maintain nutritional status in these patients.

Factors influencing survival in hemodialysis patients aged older than 75 years: 2.5-year outcome study.

The incidence of malnutrition is widely held to be greater in the elderly, but this specific factor has not been extensively studied in elderly dialysis patients. In a 30-month follow-up prospective study, we evaluated the role of nutrition on the outcome of 290 stable hemodialysis (HD) outpatients aged older than 75 years followed up in 20 French HD centers (167 men, 123 women; age, 79.8 +/- 4.2 years; previous time on dialysis, 41 +/- 38 months). On the same day in January 1996, predialysis and postdialysis blood samples were collected according to recommended procedures for dialysis quantification. Normalized protein catabolic rate, dialysis adequacy parameters, and estimation of lean body mass (LBM; expressed as observed/expected LBM values [obs/exp LBM]) were computed from predialysis and postdialysis urea and creatinine levels. Overall survival rates were 80% and 65% after 1 and 2 years of follow-up, respectively, and were significantly less in patients with the lower quartile of obs/exp LBM. In univariate analysis using the Cox proportional hazards model, survival was significantly influenced by age, albumin level, prealbumin level, body mass index, and diabetes, but not by sex, Kt/V, duration of dialysis, cholesterol level, hemoglobin level, or obs/exp LBM. In multivariate analysis, no variable remained significant. Cardiovascular mortality accounted for 52.1% of the patient deaths. We conclude that in elderly HD patients, malnutrition influences overall survival despite adequate dialysis treatment.

Urea as a marker of adequacy in hemodialysis: lesson from in vivo urea dynamics monitoring.

BACKGROUND: "Dialysis dose," a concept developed by Sargent and Gotch based on urea kinetic modeling, is a useful and recognized tool that is used to quantitate and optimize a dialysis-efficacy program. However, it has been shown that oversimplification of the "dialysis adequacy" concept to the Kt/V index might lead to dramatic underdialysis and subsequent deleterious consequences on morbidity and mortality of dialysis patients. With this perspective, the determination of Kt/V must be very cautious and rely on accurate measurement of postdialysis urea concentration and its use integrated as a tool in a quality-assurance process. METHODS: In this study, we analyzed urea dynamics by means of a blood side (ultrafiltrate) continuous online urea monitoring system interfaced with a two-pool model hosted in a microcomputer. The study was designed to provide instantaneous dialysis performances (body and dialyzer clearances, dialyzer mass transfer coefficient) and to determine the in vivo functional permeability characteristics of the patient [intercompartment urea mass transfer coefficient (Kc)]. Thirteen end-stage renal disease patients (age 54 +/- 16 years; 12 male and 1 female) were studied during nine consecutive dialysis sessions (3 weeks). RESULTS: Urea kinetics obtained from the urea monitoring system fitted closely the urea kinetic modeling prediction, confirming the validity of the double-pool model structure. Effective in vivo urea mass transfer coefficient averaged 912 +/- 235 mL/min/1.73 m2, a value close to those reported with more invasive methods. Large variations ranging from 363 to 1249 mL/min were observed among patients, confirming very large interindividual patient permeability differences. Interestingly, the urea mass transfer coefficient was inversely correlated with the postdialysis rebound values. Intraindividual variations were also noted as a function of time denoting functional changes in urea mass transfer coefficient values. The urea distribution volume was 38.1 +/- 7, 8 L (53 +/- 8% body weight). V1 referring to the extracellular volume and V2 to the intracellular volume were 9 +/- 2 L (13 +/- 2% body weight) and 29.2 +/- 6.6 L (41 +/- 1.3% body wt), respectively. The extracellular/intracellular volume ratio was 0.31 (approximately one third) and was not as usually defined by the paradigm 1/2 ratio. CONCLUSION: Online double-pool urea kinetic modeling gave a new insight in urea kinetic modeling approach. Urea dynamics fit perfectly a double-compartment model structure. Accessible extracellular volume to hemodialysis is smaller than expected. The in vivo urea mass transfer coefficient must be considered as an individual and variable characteristic of ESRD patients that should be taken into consideration when prescribing the hemodialysis schedule.