Parameters derived by ultrasonic myocardial characterization in dialysis patients are associated with mortality

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Shared decision making in patients with kidney failure

'Elderly' is most commonly defined as an individual aged 65 years or older. However, this definition fails to account for the differences in genetics, lifestyle and overall health that contribute to significant heterogeneity among the elderly beyond chronological age. As the world population continues to age, the prevalence of chronic diseases, including chronic kidney disease (CKD), is increasing and CKD frequently progresses to kidney failure. Moreover, frailty represents a multidimensional clinical entity highly prevalent in this population, which needs to be adequately assessed to inform and support medical decisions. Selecting the optimal treatment pathway for the elderly and frail kidney failure population, be it hemodialysis, peritoneal dialysis, or conservative kidney management is complex, because of the presence of comorbidities associated with low survival rates and impaired quality of life. Management of these patients should involve a multidisciplinary approach including doctors from various specialties, nurses, psychologists, dieticians, and physiotherapists. Studies are mostly retrospective and observational, lacking adjustment for confounders or address selection and indication biases, making it difficult to use these data to guide treatment decisions. Throughout this review we discuss the difficulty of making a one-size-fits-all recommendation for the clinical needs of older patients with kidney failure. We advocate that a research agenda for optimization of the critical issues we present in this review be implemented. We recommend prospective studies that address these issues, and systematic reviews incorporating the complementary evidence of both observational and interventional studies. Furthermore, we strongly support a shared decision making process matching evidence with patient preferences to ensure that individualized choices are made regarding dialysis vs. conservative kidney management, dialysis modality, and optimal vascular access

Citrate anion improves chronic dialysis efficacy, reduces systemic inflammation and prevents Chemerin-mediated microvascular injury

Systemic inflammation and uremic toxins (UT) determine the increased cardiovascular mortality observed in chronic hemodialysis (HD) patients. Among UT, the adipokine Chemerin induces vascular dysfunction by targeting both endothelial and vascular smooth muscular cells (EC and VSMC). As Citrate anion modulates oxidative metabolism, systemic inflammation and vascular function, we evaluated whether citrate-buffered dialysis improves HD efficiency, inflammatory parameters and chemerin-mediated microvascular injury. 45 patients were treated in sequence with acetate, citrate and, again, acetate-buffered dialysis solution (3 months per interval). At study admission and after each treatment switch, we evaluated dialysis efficacy and circulating levels of chemerin and different inflammatory biomarkers. In vitro, we stimulated EC and VSMC with patients' plasma and we investigated the role of chemerin as UT. Citrate dialysis increased HD efficacy and reduced plasma levels of CRP, fibrinogen, IL6 and chemerin. In vitro, patients' plasma induced EC and VSMC dysfunction. These effects were reduced by citrate-buffered solutions and paralleled by the decrease of chemerin levels. Consistently, chemerin receptor knockdown reduced EC and VSMC dysfunction. In conclusion, Switching from acetate to citrate improved dialysis efficacy and inflammatory parameters; in vitro, chemerin-induced EC and VSMC injury were decreased by using citrate as dialysis buffer

Citrate high volume on-line hemodiafiltration modulates serum Interleukin-6 and Klotho levels: the multicenter randomized controlled study \u201cHephaestus

Background: Studies addressing the anti-inflammatory properties of citrate dialysate enrolled patients in both hemodialysis (HD) and hemodiafiltration (HDF), the latter not adjusted for adequate convective exchange. This is a potential source of confounding in that HDF itself has anti-inflammatory effects regardless of the buffer, and optimal clinical outcomes are related to the amount of convection. Methods: To distinguish the merits of the buffer from those of convection, we performed a 6-month, prospective, randomized, crossover AB-BA study. Comparisons were made during the 3-month study period of on-line HDF with standard dialysate containing three mmol of acetic acid (OL-HDFst) and the 3-month of OL-HDF with dialysate containing one mmol of citric acid (OL-HDFcit). Primary outcome measure of the study was interleukin-6 (IL-6). Klotho, high sensitivity C-reactive protein (hsCRP), fetuin and routine biochemical parameters were also analyzed. Results: We analyzed 47 patients (mean age 64 years, range 27-84 years) enrolled in 10 participating Nephrology Units. Convective volumes were around 25 L/session with 90 percent of sessions > 20 L and f2-microglobulin reduction rate 76% in both HDFs. Baseline median IL-6 values in OL-HDFst were 5.6 pg/ml (25:75 interquartile range IQR 2.9:10.6) and in OL-HDFcit 6.6 pg/ml (IQR 3.4:11.4 pg/ml). The difference was not statistically significant (p 0.88). IL-6 values were lower during OL-HDFcit than during OL-HDFst, both when analyzed as the median difference of overall IL-6 values (p 0.02) and as the median of pairwise differences between the baseline and the 3-month time points (p 0.03). The overall hsCRP values too, were lower during OL-HDFcit than during OL-HDFst (p 0.01). Klotho levels showed a time effect (p 0.02) and the increase was significant only during OL-HDFcit (p 0.01). Conclusions: Citrate buffer modulated IL-6, hsCRP and Klotho levels during high volume OL-HDF. These results are not attributable to differences in the dialysis schedule and may suggest a potential anti-inflammatory and anti-senescent effect of citrate even in dialysis patients with low grade inflammatio

Associations between depressive symptoms and disease progression in older patients with chronic kidney disease: results of the EQUAL study

Background Depressive symptoms are associated with adverse clinical outcomes in patients with end-stage kidney disease; however, few small studies have examined this association in patients with earlier phases of chronic kidney disease (CKD). We studied associations between baseline depressive symptoms and clinical outcomes in older patients with advanced CKD and examined whether these associations differed depending on sex. Methods CKD patients (>= 65 years; estimated glomerular filtration rate <= 20 mL/min/1.73 m(2)) were included from a European multicentre prospective cohort between 2012 and 2019. Depressive symptoms were measured by the five-item Mental Health Inventory (cut-off <= 70; 0-100 scale). Cox proportional hazard analysis was used to study associations between depressive symptoms and time to dialysis initiation, all-cause mortality and these outcomes combined. A joint model was used to study the association between depressive symptoms and kidney function over time. Analyses were adjusted for potential baseline confounders. Results Overall kidney function decline in 1326 patients was -0.12 mL/min/1.73 m(2)/month. A total of 515 patients showed depressive symptoms. No significant association was found between depressive symptoms and kidney function over time (P = 0.08). Unlike women, men with depressive symptoms had an increased mortality rate compared with those without symptoms [adjusted hazard ratio 1.41 (95% confidence interval 1.03-1.93)]. Depressive symptoms were not significantly associated with a higher hazard of dialysis initiation, or with the combined outcome (i.e. dialysis initiation and all-cause mortality). Conclusions There was no significant association between depressive symptoms at baseline and decline in kidney function over time in older patients with advanced CKD. Depressive symptoms at baseline were associated with a higher mortality rate in men

Numerical analysis of deterioration in heat transfer to near-critical rocket propellants

Liquid propellants, which are typically used for regenerative cooling of rocket thrust chambers, can flow in channels at supercritical pressures and in the neighborhood of pseudocritical temperature (near-critical fluid). This could be for instance the case for the envisioned liquid-oxygen/liquid-methane engines with chamber pressures larger than about 50bar. When the fluid is in such a near-critical condition, deterioration in heat transfer can occur if the heat transfer level is higher than a threshold value. Aiming to improve flow prediction capabilities for the design of such systems, the present study is devoted to numerical simulations of near-critical fluids flowing in uniformly heated straight tubes. After code validation against experimental data of near-critical-hydrogen flow, numerical simulations of near-critical-methane flow in heated tubes are carried out, each characterized by a different wall heat flux. Results are discussed in detail and the near-critical-methane flow condition that exhibits the heat transfer deterioration is identified and emphasized. Copyright © Taylor & Francis Group, LLC

A simplified model for the analysis of thermal stratification in cooling channels

The analysis of the flow in the cooling channels of liquid rocket engine thrust chambers is of paramount importance in their structural thermal design. The complete information can only be obtained by costly experiments or by complex numerical simulations, because of the three-dimensional shape of channels and of the coupling among flow evolution in hot-gas and coolant sides and wall heat transfer. Moreover, the coolant is often a supercritical fluid, which needs its appropriate equation of state. A simplified approach is developed in the present paper which, relying on empirical relationships, is able to study the thermal stratification in both the coolant flow and the cooling channel structures

Numerical Analysis of Transcritical Fluids Heating in Liquid Rocket Engine Cooling Channels

The modeling and the analysis of the coolant flow in rocket engine applications is a challenging task because of its particular features, such as the extremely high heat flux (up to 10 MW/m^2), the high Reynolds number (up to 10^7) and the three-dimensional geometry of the channel. A further complication that may arise is the transcritical operating condition of the fluid, which can greatly influence the coolant flow-field and the heat transfer. In the present work numerical simulations of supercritical nitrogen and transcritical hydrogen flow in heated circular channels are validated against experimental data. Also numerical simulations of transcritical-methane in circular straight channels are carried out to analyse the dependence of heat transfer deterioration on the assigned heat load. Results are discussed in detail and the transcritical-methane flow condition that exhibits the heat transfer deterioration is identified and emphasized. Finally a comparison with the empirical correlations known in literature is made to see if they can correctly predict the behaviour of transcritical methane

Numerical Investigation of Transcritical Fluid Flow and Heat Transfer in Channels

Modeling the coolant flow in regeneratively cooled rocket engines is a challenging task because of high wall temperature gradients, high Reynolds number and 3D-geometry of the passages. In case of methane as coolant, a further complication is the trans-critical operating condition of the fluid,which can greatly influence the coolant flow field and heat transfer. In the present paper a 3D Navier-Stokes solver for real gas is first validated for trans-critical hydrogen flows, then it is used to study the 3D flow fields of transcritical methane flow in rectangular cross section cooling channels. Finally, the results obtained for a reference straight channel flow are compared with those of a simplified approach based on empirical relations which could be more easily used in the engine design phase

Transcritical Methane Flows in LRE Cooling Channels

The knowledge of the flow behavior inside cooling channels is of great importance to improve design and performance of regeneratively cooled rocket engines. The modeling of the coolant flow is a challenging task because of its particular features, such as the high wall temperature gradient, the high Reynolds number and the 3Dgeometry of the passages. In case of Methane as coolant, a further complication is the transcritical operating condition of the fluid. In this thermodynamic regime large changes in the fluid properties can greatly influence the coolant flowfield and the heat transfer. In the present work a 3D-CFD code, able to describe the turbulent coolant flow inside the rectangular cooling channels with high aspect ratio is developed. Then, solutions of the transcritical Methane flowfield in asymmetrically heated 3D channel with high aspect ratio and strong wall temperature differences are presented and discussed