Osteocalcin and myoglobin removal in on-line hemodiafiltration versus low- and high-flux hemodialysis

Does online high-volume hemodiafiltration offer greater efficiency and sustainability compared with high-flux hemodialysis? A detailed simulation analysis anchored in real-world data

Recent findings, including the CONVINCE (comparison of high-dose HDF with high-flux HD) study report, suggest the superiority of high-volume hemodiafiltration (HDF) over high-flux hemodialysis (HD) in improving patients' outcomes. Despite positive patient outcomes, concerns have arisen about the potential negative environmental impact of high-volume HDF, as it may lead to increased water and dialysis fluid consumption and higher waste production. In this manuscript, we address the environmental impact of high-volume HDF, focusing on three key factors: water treatment consumption, dialysis fluid consumption, and solute efficiency markers of HD and HDF. By optimizing HDF prescription through adjustments in operational capabilities, while keeping a high blood flow (i.e., >350 ml/min) such as reducing the QD/QB ratio to 1.2 rather than 1.4 or 1.5 and incorporating automated ultrafiltration and substitution control, we demonstrate that HDF delivers a higher dialysis dose for small- and middle-molecule uremic compounds with the same dialysis fluid consumption, and at equal dialysis doses dialysis fluid consumption is reduced. This finding is supported by real-world data from 26 031 patients who underwent high-volume postdilution HDF at a reduced dialysis flow (430 mL/min) and achieved an effective OCMKt/V of 1.70 (where "OCM" stands for online clearance measurement, "K" represents effective dialysis clearance and "V" denotes total body water measured by multifrequency bioimpedance). In addition, simulation modeling calculations, using blood extraction coefficient, dialysate saturation coefficient and solute clearances with urea (small molecular weight) and β2-microglobulin (middle molecular weight), consistently show the superiority of postdilution HDF to HD. This holds true even with a significant reduction in dialysis flow down to 430 mL/min, reflecting QD/QB ratio of 1.2. Postdilution HDF generates high ultrafiltrate flow (up to 35% of blood flow), delivering saturated ultrafiltrate to the lower solute concentration containing effluent dialysate, thus enhancing solute clearance which opens the way to reduce the dialysis flow. In conclusion, our analysis, combining simulation and real-world data, suggests that postdilution HDF could be a more environmentally friendly treatment option compared with conventional HD. Additionally, automated user-friendly functions that minimize dialysis fluid use can further strengthen this environmental benefit while enhancing efficiency.

Management of Poisonings and Intoxications

Poisoning occurs after exposure to any of a number of substances, including medicines, which can result in severe toxicity including death. The nephrologist may be involved in poisonings that cause kidney disease and for targeted treatments. The overall approach to the poisoned patient involves the initial acute resuscitation and performing a risk assessment, whereby the exposure is considered in terms of the anticipated severity and in the context of the patient's status and treatments that may be required. Time-critical interventions such as gastrointestinal decontamination ( e.g. , activated charcoal) and antidotes are administered when indicated. The nephrologist is usually involved when elimination enhancement techniques are required, such as urine alkalinization or extracorporeal treatments. There is increasing data to guide decision making for the use of extracorporeal treatments in the poisoned patient. Principles to consider are clinical indications such as whether severe toxicity is present, anticipated, and/or will persist and whether the poison will be significantly removed by the extracorporeal treatment. Extracorporeal clearance is maximized for low-molecular weight drugs that are water soluble with minimal protein binding (<80%) and low endogenous clearance and volume of distribution. The dosage of some antidotes ( e.g. , N-acetylcysteine, ethanol, fomepizole) should be increased to maintain therapeutic concentrations once the extracorporeal treatment is initiated. To maximize the effect of an extracorporeal treatment, blood and effluent flows should be optimized, the filter with the largest surface area selected, and duration tailored to remove enough poison to reduce toxicity. Intermittent hemodialysis is recommended in most cases when an extracorporeal treatment is required because it is the most efficient, and continuous kidney replacement therapy is prescribed in some circumstances, particularly if intermittent hemodialysis is not readily available.

Hemodiafiltration: Technical and Medical Insights

Despite the significant medical and technical improvements in the field of dialytic renal replacement modalities, morbidity and mortality are excessively high among patients with end-stage kidney disease, and most interventional studies yielded disappointing results. Hemodiafiltration, a dialysis method that was implemented in clinics many years ago and that combines the two main principles of hemodialysis and hemofiltration-diffusion and convection-has had a positive impact on mortality rates, especially when delivered in a high-volume mode as a surrogate for a high convective dose. The achievement of high substitution volumes during dialysis treatments does not only depend on patient characteristics but also on the dialyzer (membrane) and the adequately equipped hemodiafiltration machine. The present review article summarizes the technical aspects of online hemodiafiltration and discusses present and ongoing clinical studies with regards to hard clinical and patient-reported outcomes.

The rationale and clinical potential of on-line hemodiafiltration as renal replacement therapy

On-line hemodiafiltration (ol-HDF) was developed in the 1980s in response to the unmet medical needs observed with conventional low- and high-flux hemodialysis. Firstly, the limited overall efficacy of conventional HD treatment programs as compared to native kidney function has been consistently documented over the broad MW spectrum of uremic toxins as well as fluid volume and hemodynamic control. Secondly, the unphysiological profile of intermittent treatment leading to repetitive dialysis-induced hemodynamic stress is now a well-recognized component of cardiovascular disease and end organ damage. Thirdly, the bioincompatibility of patient-dialysis system leading to dialysis-induced biological reactions also identified as contributing to dialytic morbidity and mortality. To overcome these limitations and pitfalls, alternative convective-based therapies (hemofiltration and hemodiafiltration), using higher hemoincompatible membranes and ultrapure dialysis fluid, were proposed as a solution to enhance and enlarge MW spectrum of uremic compounds cleared and to reduce dialysis-patient biological interactions. In this context, online HDF appeared soon as the best viable and efficient renal replacement modality to cover these needs. Clinical development and implementation of ol-HDF showed also that dialytic convective dose matters with a threshold point (23 L/1.73 m² in postdilution mode) to observe clinical benefits and outcomes improvements.

Why and how high volume hemodiafiltration may reduce cardiovascular mortality in stage 5 chronic kidney disease dialysis patients? A comprehensive literature review on mechanisms involved

Online hemodiafiltration (HDF) is an established renal replacement modality for patients with end stage chronic kidney disease that is now gaining rapid clinical acceptance worldwide. Currently, there is a growing body of evidence indicating that treatment with HDF is associated with better outcomes and reduced cardiovascular mortality for dialysis patients. In this comprehensive review, we provide an update on the potential mechanisms which may improve survival in HDF treated patients. The strongest evidence is for better hemodynamic stability and reduced endothelial dysfunction associated with HDF treatments. Clinically, this is marked by a reduced incidence of intradialytic hypotensive episodes, with a better hemodynamic response to ultrafiltration, mediated by an increase in total peripheral vascular resistance and extra-vascular fluid recruitment, most likely driven by the negative thermal balance associated with online HDF therapy. In addition, endothelial function appears to be improved due to a combination of a reduction of the inflammatory and oxidative stress complex syndrome and exposure to circulating cardiovascular uremic toxins. Reports of reversed cardiovascular remodeling effects with HDF may be confounded by volume and blood pressure management, which are strongly linked to center clinical practices. Currently, treatment with HDF appears to improve the survival of dialysis patients predominantly due to a reduction in their cardiovascular burden, and this reduction is linked to the sessional convection volume exchanged.

Recent advances in dialysis membranes

PURPOSE OF REVIEW

Improvement in hemodialysis treatment and membrane technology are focused on two aims: the first one is to achieve a better control of circulating uremic solutes by enhancing removal capacity and by broadening molecular weight spectrum of solutes cleared; the second one is to prevent inflammation by improving hemocompatibility of the global dialysis system.

RECENT FINDINGS

Despite impressive progresses in polymers chemistry few hazards are still remaining associated with leaching or sensitization to polymer additives. Research has focused on developing more stable polymers by means of additives or processes aiming to minimize such risks. Membrane engineering manufacturing with support of nanocontrolled spinning technology has opened up membrane to middle and large molecular weight substances, while preserving albumin losses. Combination of diffusive and enhanced convective fluxes in the same hemodialyzer module, namely hemodiafiltration, provides today the highest solute removal capacity over a broad spectrum of solutes.

SUMMARY

Dialysis membrane is a crucial component of the hemodialysis system to optimize solute removal efficacy and to minimize blood membrane biological reactions. Hemodialyzer is much more than a membrane. Dialysis membrane and hemodialyzer choice are parts of a treatment chain that should be operated in optimized conditions and adjusted to patient needs and tolerance, to improve patient outcomes.

The efficiency of continuous renal replacement therapy for rewarming of patients in accidental hypothermia--An experimental study

Severe accidental hypothermia carries high mortality and morbidity and is often treated with invasive extracorporeal methods. Continuous veno-venous hemodiafiltration (CVVHDF) is widely available in intensive care units. We sought to provide theoretical basis for CVVHDF use in rewarming of hypothermic patients. CVVHDF system was used in the laboratory setting. Heat balance and transferred heat units were evaluated for the system without using blood. We used 5L of crystalloid solution at the temperature of approximately 25°C, placed in a thermally insulated tank (representing the "central compartment" of a hypothermic patient). Time of warming the central compartment from 24.9 to 30.0°C was assessed with different flow combinations: "blood" (central compartment fluid) 50 or 100 or 150 mL/min, dialysate solution 100 or 1500 mL/h, and substitution fluid 0 or 500 mL/h. The total circulation time was 1535 minutes. There were no differences between heat gain values on the filter depending on blood flow (P = .53) or dialysate flow (P = .2). The mean heating time for "blood" flow rates 50, 100, and 150 mL/min was 113.7 minutes (95% CI, 104.9-122.6 minutes), 83.3 minutes (95% CI, 76.2-90.3 minutes), and 74.7 minutes (95% CI, 62.6-86.9 minutes), respectively (P < .01). The respective median rewarming rate for different "blood" flows was 3.6°C/h (IQR, 3.0-4.2°C/h), 4.8 (IQR, 4.2-5.4°C/h), and 5.4 (IQR, 4.8-6.0°C/h), respectively (P < .01). The dialysate flow did not affect the warming rate. Based on our experimental model, CVVHDF may be used for extracorporeal rewarming, with the rewarming rates increasing achieved with higher blood flow rates.

Performance and Hemocompatibility of a Novel Polysulfone Dialyzer: A Randomized Controlled Trial

Background

High-flux dialyzers effectively remove uremic toxins, are hemocompatible to minimize intradialytic humoral and cellular stimulation, and have long-term effects on patient outcomes. A new dialyzer with a modified membrane surface has been tested for performance and hemocompatibility.

Methods

This multicenter, prospective, randomized, crossover study involved the application of the new polysulfone-based FX CorAL 600 (Fresenius Medical Care, Bad Homburg, Germany), the polyarylethersulfone-based Polyflux 170H (Baxter Healthcare Corporation, Deerfield, IL), and the cellulose triacetate–based SureFlux 17UX (Nipro Medical Europe, Mechelen, Belgium), for 1 week each, to assess the noninferiority of the FX CorAL 600’s removal rate of β2-microglobulin. Performance was assessed by removal rate and clearance of small- and medium-sized molecules. Hemocompatibility was assessed through markers of complement, cell activation, contact activation, and coagulation.

Results

Of 70 patients, 58 composed the intention-to-treat population. The FX CorAL 600’s removal rate of β2-microglobulin was noninferior to both comparators (P<0.001 versus SureFlux 17UX; P=0.0006 versus Polyflux 170H), and superior to the SureFlux 17UX. The activation of C3a and C5a with FX CorAL 600 was significantly lower 15 minutes after treatment start than with SureFlux 17UX. The activation of sC5b-9 with FX CorAL 600 was significantly lower over the whole treatment than with SureFlux 17UX, and lower after 60 minutes than with the Polyflux 170H. The treatments with FX CorAL 600 were well tolerated.

Conclusions

FX CorAL 600 efficiently removed small- and medium-sized molecules, showed a favorable hemocompatibility profile, and was associated with a low frequency of adverse events in this study, with a limited patient number and follow-up time. Further studies, with longer observation times, are warranted to provide further evidence supporting the use of the new dialyzer in a wide range of therapeutic options, and for long-term treatment of patients on hemodialysis, to minimize the potential effects on inflammatory processes.

Updates on hemodialysis techniques with a common denominator: The personalization of the dialytic therapy

Hemodialysis (HD) is a life-saving therapy for patients with end-stage renal disease. In dialyzed patients, the prevalence of multi-morbidity is rising driven by various factors, such as the population aging, the incomplete correction of uremia, and the side effects of the dialysis therapy itself. Each dialyzed patient has their own specific clinical and biochemical problems. It is therefore unthinkable that the same dialysis procedure can be able to meet the needs of every patient on chronic dialysis. We have very sophisticated dialysis machines and different dialysis techniques and procedures beyond conventional HD, such as hemodiafiltration (HDF) with pre- and post-dilution, acetate-free biofiltration (AFB), hemofiltration (HF), and expanded HD. Each of these techniques has its own specific characteristics. To solve some intradialytic clinical issues, such as arterial hypotension and arrhythmias, we have biofeedback systems with automatic regulation of the blood volume, body temperature, arterial pressure, as well as potassium profiling techniques in the dialysis bath. New technical innovations, such as citrate-containing dialysate or heparin-coated membranes, could reduce the risk of bleeding. To better address to patient needs, the strengths and weaknesses of each of these systems must be well-known, in order to have a personalized dialysis prescription for each patient.

Combination of Multiple Hemodialysis Modes: Better Treatment Options for Patients Under Maintenance Hemodialysis

Purpose

Chronic renal failure has become a major public health concern and treatment strategies are urgently needed. We aimed to investigate whether combination of hemodialysis modes was superior to regular hemodialysis for patients under maintenance hemodialysis.

Patients and Methods

A total of 144 patients with end-stage renal failure (ESRF) were enrolled in this single-center retrospective study. Patients received regular hemodialysis (HD) were included in HD group (n=52), patients received regular HD plus hemodiafiltration (HDF) in HD/HDF group (n=47), patients received the combination of regular HD, HDF and hemoperfusion (HP) in HD/HDF/HP group (n=45). After 1-month and 24-months treatment, therapeutic effects were assessed in terms of nutritional status, control of complications, dialysis adequacy, mean arterial pressure (MAP), infection rate and living quality.

Results

When patients received 1-month treatment, there were no statistically significant differences among three groups. After 24-months treatment, patients in HD/HDF and HD/HDF/HP group presented with better dialysis adequacy, lower MAP and infection rate, higher serum albumin, hemoglobin and calcium levels, lower serum phosphorus and intact parathyroid hormone levels, lower incidence of malnutrition and the Hamilton Depression Scale score, higher the Barthel Index score than HD group (P<0.05). The levels of calcium, phosphorus and intact parathyroid hormone in HD/HDF/HP group were lower than those in HD/HDF group (P<0.05).

Conclusion

Our finding highly indicated that combination of hemodialysis modes was superior to regular HD for patients with ESRF in nutritional status, control of complications, dialysis adequacy, and living quality.

The renal replacement therapy landscape in 2030: reducing the global cardiovascular burden in dialysis patients

Despite the significant progress made in understanding chronic kidney disease and uraemic pathophysiology, use of advanced technology and implementation of new strategies in renal replacement therapy, the clinical outcomes of chronic kidney disease 5 dialysis patients remain suboptimal. Considering residual suboptimal medical needs of short intermittent dialysis, it is our medical duty to revisit standards of dialysis practice and propose new therapeutic options for improving the overall effectiveness of dialysis sessions and reduce the burden of stress induced by the therapy. Several themes arise to address the modifiable components of the therapy that are aimed at mitigating some of the cardiovascular risks in patients with end-stage kidney disease. Among them, five are of utmost importance and include: (i) enhancement of treatment efficiency and continuous monitoring of dialysis performances; (ii) prevention of dialysis-induced stress; (iii) precise handling of sodium and fluid balance; (iv) moving towards heparin-free dialysis; and (v) customizing electrolyte prescriptions. In summary, haemodialysis treatment in 2030 will be substantially more personalized to the patient, with a clear focus on cardioprotection, volume management, arrhythmia surveillance, avoidance of anticoagulation and the development of more dynamic systems to align the fluid and electrolyte needs of the patient on the day of the treatment to their particular circumstances.

Removal of large middle molecules via haemodialysis with medium cut-off membranes at lower blood flow rates: an observational prospective study

Background

Online haemodiafiltration (OL-HDF) may improve middle molecular clearance in contrast to conventional haemodialysis (HD). However, OL-HDF requires higher convective flows and cannot sufficiently remove large middle molecules. This study evaluated the efficacy of a medium cut-off (MCO) dialyser in removing large middle molecular uraemic toxins and compared it with that of conventional high-flux (HF) dialysers in HD and predilution OL-HDF.

Methods

Six clinically stable HD patients without residual renal function were investigated. Dialyser and treatment efficacies were examined during a single midweek treatment in three consecutive periods: 1) conventional HD using an HF dialyser, 2) OL-HDF using the same HF dialyser, and 3) conventional HD using an MCO dialyser. Treatment efficacy was assessed by calculating the reduction ratio (RR) for β2-microglobulin (β2M), myoglobin, κ and λ free light chains (FLCs), and fibroblast growth factor (FGF)-23 and measuring clearance for FLCs.

Results

All three treatments showed comparable RRs for urea, phosphate, creatinine, and uric acid. MCO HD showed greater RRs for myoglobin and λFLC than did HF HD and predilution OL-HDF (myoglobin: 63.1 ± 5.3% vs. 43.5 ± 8.9% and 49.8 ± 7.3%; λFLC: 43.2 ± 5.6% vs. 26.8 ± 4.4% and 33.0 ± 9.2%, respectively; P <  0.001). Conversely, predilution OL-HDF showed the greatest RR for β2M, whereas MCO HD and HF HD showed comparable RRs for β2M (predilution OL-HDF vs. MCO HD: 80.1 ± 4.9% vs. 72.6 ± 3.8%, P = 0.01). There was no significant difference among MCO HD, HF HD, and predilution OL-HDF in the RRs for κFLC (63.2 ± 6.0%, 53.6 ± 15.5%, and 61.5 ± 7.0%, respectively; P = 0.37), and FGF-23 (55.5 ± 20.3%, 34.6 ± 13.1%, and 35.8 ± 23.2%, respectively; P = 0.13). Notably, MCO HD showed improved clearances for FLCs when compared to HF HD or OL-HDF.

Conclusions

MCO HD showed significantly greater RR of large middle molecules and achieved improved clearance for FLCs than conventional HD and OL-HDF, without the need for large convection volumes or high blood flow rates. This would pose as an advantage for elderly HD patients with poor vascular access and HD patients without access to OL-HDF.

Trial registration

Clinical Research Information Service (CRIS): KCT 0003009. The trial was prospectively registered on the 21 Jul 2018.

Clinical evidence on haemodiafiltration

Haemodiafiltration (HDF) combines diffusive and convective solute removal in a single treatment session. HDF provides a greater removal of higher molecular weight uraemic retention solutes than conventional high-flux haemodialysis (HD). Recently completed randomized clinical trials suggest better patient survival with online HDF. The treatment is mainly used in Europe and Japan. This review gives a brief overview of the presently available evidence of the effects of HDF on clinical end points, it speculates on possible mechanisms of a beneficial effect of HDF as compared with standard HD and ends with some perspectives for the future.

A unidimensional diffusion model applied to uremic toxin kinetics in haemodiafiltration treatments

Kinetic modelling in haemodialysis is usually based upon the resolution of volume-defined compartment models. The interaction among these compartments is described by purely diffusive processes. In this paper we present an alternative kinetic model for uremic toxins in post-dilutional haemodiafiltration treatments by means of a unidimensional diffusion equation. A wide range of solutes such as urea, creatinine, $\beta _{2}$-microglobulin, myoglobin and prolactin were studied by imposing appropriate boundary and initial conditions in a virtual [0,1] domain. The diffusivity along the domain and the extraction rate at the dialyser are the kinetic parameters which were fitted by least-squares for every studied solute. The accuracy of the presented volumeless model as well as the behavior of the proposed kinetic parameters could be an alternative to the compartment description for a variety of molecular weight uremic toxins undergoing different treatment configurations.

Pyrogen retention: Comparison of the novel medium cut-off (MCO) membrane with other dialyser membranes

Haemodialysis effectively removes small solutes and smaller-sized middle molecules from the blood; however, the clearance of larger middle molecules, which have been associated with negative effects, is poor. The novel medium cut-off (MCO) dialysis membrane has larger pore sizes and a more open structure than other high-flux membranes, providing improved removal of larger middle molecules while retaining albumin. However, larger pore sizes may potentially increase permeability to pyrogens, including endotoxins and other bacterial contaminants, that could be present in the dialysis fluid. In this study, we tested the capacity of low-flux, high-flux, MCO and high cut-off dialyser membranes with different pore sizes to prevent pyrogens crossing from dialysate to the blood side in a closed-loop test system, differentiating among lipopolysaccharides, peptidoglycans and bacterial DNA using a toll-like receptor assay. Even though the bacterial contamination levels in our test system exceeded the acceptable pyrogen dose for standard dialysis fluid, levels of lipopolysaccharides, peptidoglycans and bacterial DNA in the blood-side samples were too low to identify potential differences in pyrogen permeability among the membranes. Our results suggest that MCO membranes are suitable for haemodialysis using ISO standard dialysis fluid quality, and retain endotoxins at a similar level as other membranes.

Effects of high-volume online mixed-hemodiafiltration on anemia management in dialysis patients

Background

Anemia is a major comorbidity of patients with end-stage renal disease and poses an enormous economic burden to health-care systems. High dose erythropoiesis-stimulating agents (ESAs) have been associated with unfavorable clinical outcomes. We explored whether mixed-dilution hemodiafiltration (Mixed-HDF), based on its innovative substitution modality, may improve anemia outcomes compared to the traditional post-dilution hemodiafiltration (Post-HDF).

Methods

We included 174 adult prevalent dialysis patients (87 on Mixed-HDF, 87 on Post-HDF) treated in 24 NephroCare dialysis centers between January 2010 and August 2016 into this retrospective cohort study. All patients were dialyzed three times per week and had fistula/graft as vascular access. Patients were matched at baseline and followed over a one-year period. The courses of hemoglobin levels (Hb) and monthly ESA consumption were compared between the two groups with linear mixed models.

Results

Mean baseline Hb was 11.9±1.3 and 11.8±1.1g/dl in patients on Mixed- and Post-HDF, respectively. While Hb remained stable in patients on Mixed-HDF, it decreased slightly in patients on Post-HDF (at month 12: 11.8±1.2 vs 11.1±1.2g/dl). This tendency was confirmed by our linear mixed model (p = 0.0514 for treatment x time interaction). Baseline median ESA consumption was 6000 [Q1:0;Q3:16000] IU/4 weeks in both groups. Throughout the observation period ESA doses tended to be lower in the Mixed-HDF group (4000 [Q1:0;Q3:16000] vs 8000 [Q1:0;Q3:20000] IU/4 weeks at month 12; p = 0.0791 for treatment x time interaction). Sensitivity analyses, adjusting for differences not covered by matching at baseline, strengthened our results (Hb: p = 0.0124; ESA: p = 0.0687).

Conclusions

Results of our explorative study suggest that patients on Mixed-HDF may have clinical benefits in terms of anemia management. This may also have a beneficial economic impact. Future studies are needed to confirm our hypothesis-generating results and to provide additional evidence on the potential beneficial effects of Mixed-HDF.

Removal capacity of different high-flux dialyzers during postdilution online hemodiafiltration

INTRODUCTION

The aim of this study is to compare molecule removal and albumin leakage in postdilution online hemodiafiltration with different high-flux dialyzers.

METHODS

We studied seven high-flux dialyzers (Polyflux 210H®, Evodial 2.2®, FxCordiax1000®, Elisio21H®, TS-2.1SL®, XevontaHi20®, VitaPES 210-HF®) in 6 patients. The reduction ratio (RR) of small- and middle-sized molecules was calculated. Dialysate samples were collected to estimate the albumin leakage.

FINDINGS

Global differences between dialyzers were observed in the RR of ß2 microglobulin (P =0.003) and prolactin (P =0.013). The mean loss of albumin in the dialysate per session varied between 114 ± 67 mg (with Evodial 2.2) and 2621 ± 1363 mg per session (with XevontaHi20). We found global differences between dialyzers in total albumin loss (P = 0.05).

DISCUSSION

We demonstrated that the performance of high-flux dialyzers was different among the types and that not all high-flux dialyzers should be considered equal.

Requirements and Pitfalls of Dialyzer Sieving Coefficients Comparisons

Sieving coefficients reported in dialyzer data sheets and instructions for use (IFUs) indicate the potential of different solutes to pass across a particular membrane. Despite being measured in vitro, sieving coefficient data are often used as a predictor of the clinical performance of dialyzers. Although standards for the measurement of sieving coefficients exist, the stated methodologies do not offer sufficient guidance to ensure comparability of test results between different dialyzers. The aim of this work was to investigate the relationship between sieving coefficients and published clinical performance indicators for two solutes, albumin loss and beta‐2 microglobulin (β₂M) reduction ratio (RR), and to assess the impact of different in vitro test parameters on sieving coefficient values for albumin, β₂M, and myoglobin. Clinical albumin loss and β₂M RR for commercially available dialyzers used in hemodialysis (HD) and post‐dilution hemodiafiltration (HDF) were extracted from the literature and plotted against sieving coefficients reported in data sheets and IFUs. Albumin, β₂M, and myoglobin sieving coefficients of a selection of dialyzers were measured per the ISO 8637 standard. The impact of in vitro testing conditions was assessed by changing blood flow rate, ultrafiltration (UF) rate, sampling time, and origin of test plasma. Results showed variation in albumin loss and β₂M RR for the same sieving coefficient across different dialyzers in HD and HDF. Changes in blood flow rates, UF rates, sampling time, and test plasma (bovine vs. human) caused marked differences in sieving coefficient values for all investigated solutes. When identical testing conditions were used, sieving coefficient values for the same dialyzer were reproducible. Testing conditions have a marked impact on the measurement of sieving coefficients, and values should not be compared unless identical conditions are used. Further, variability in observed clinical data in part reflects the lack of definition of test conditions.

Acute kidney injury secondary to traumatic rhabdomyolysis in a dog

OBJECTIVE

To describe the clinical course and successful management of a dog with crush syndrome, rhabdomyolysis, myoglobinuria, and associated acute kidney injury (AKI).

CASE SUMMARY

An 8-year-old female, neutered, mixed-breed dog was referred to the Veterinary Teaching Hospital due to crush injury and suspected AKI. Blood tests and urinalysis showed markedly increased serum creatine kinase activity, myoglobinuria, and AKI. The dog was managed successfully with intermittent hemodialysis, and completely recovered.

NEW OR UNIQUE INFORMATION PROVIDED

This is the first report of a dog with crush syndrome with secondary myoglobinuria and AKI.

Hemodiafiltration to Address Unmet Medical Needs ESKD Patients

Hemodiafiltration combines diffusive and convective solute removal in a single therapy by ultrafiltering 20% or more of the blood volume processed using a high-flux hemodialyzer and maintaining fluid balance by infusing sterile nonpyrogenic replacement fluid directly into the patient's blood. In online hemodiafiltration, the large volumes of replacement fluid required are obtained by online filtration of standard dialysate through a series of bacteria- and endotoxin-retaining filters. Currently available systems for online hemodiafiltration are on the basis of conventional dialysis machines with added features to safely prepare and infuse replacement fluid and closely control fluid balance. Hemodiafiltration provides greater removal of higher molecular weight uremic retention solutes than conventional high-flux hemodialysis, and recently completed randomized, controlled clinical trials suggest better patient survival with online hemodiafiltration compared with standard high-flux hemodialysis when a high convection volume is delivered. Hemodiafiltration is also associated with improvements in other clinical outcomes, such as a reduction in intradialytic hypotension, and it is now used routinely to treat >100,000 patients, mainly in Europe and Japan.

Optimized convective transport with automated pressure control in on-line postdilution hemodiafiltration

Purpose

In a stable patient population we evaluated on-line postdilution hemodiafiltration (HDF) on the incremental improvement in blood purification versus high-flux HD, using the same dialyzer and blood flow rate. For HDF we used a new way of controlling HDF treatments based on the concept of constant pressure control where the trans-membrane pressure is automatically set by the machine using a feedback loop on the achieved filtration (HDF UC).

Methods

We enrolled 20 patients on on-line HDF treatment and during a 4-week study period recorded key treatment parameters in HDF UC. For one mid-week study treatment performed in HD and one midweek HDF UC treatment we sampled blood and spent dialysate to evaluate the removal of small- and middle-sized solutes.

Results

We achieved 18±3 liters of ultrafiltration in four-hour HDF UC treatments, corresponding to 27±3% of the treated blood volume. That percentage varied by patient hematocrit level. The ultrafiltration amounted to 49±4% of the estimated plasma water volume treated. We noted few machine alarms. For β2m and factor D the effective reduction in plasma level by HDF (76±6% and 43±9%, respectively) was significantly greater than in HD, and a similar relation was seen in mass recovered in spent dialysate. Small solute removal was similar in HDF and HD. Albumin loss was low.

Conclusion

The additional convective transport provided by on-line HDF significantly improved the removal of middle molecules when all other treatment settings were equal. Using the automated pressure control mode in HDF, the convective volume depended on the blood volume processed and the patient hematocrit level.

Evaluation of the dialyser inner diameter in online haemodiafiltration

INTRODUCTION

Online haemodiafiltration (OL-HDF) has been associated with increased survival. To date, the influence of the inner diameter of the hollow fibres of the dialyser on convective volume has not been well established. The objective of the study was to evaluate the effect of increasing the inner diameter of the dialyser on the convective volume and removal capacity.

MATERIAL AND METHODS

We included 16 patients in posdilutional OL-HDF with autosubstitution. Each patient was analysed in 4 sessions in which the inner diameter varied; 185μm (FX60 Cordiax and FX80 Cordiax) versus 210μm (FX600 Cordiax and FX800 Cordiax). Different solutes were measured at the beginning and end of each dialysis session.

RESULTS

No differences in the convective volume were found with an increased inner diameter: 32.3±3.1 vs. 31.8±3.6 l/session (FX60 vs. FX600) and 33.7±4.3 vs. 33.5±3.8 l/session (FX80 vs. FX800). The reduction percentages also did not differ: urea 83.7±4.5 vs. 84.1±3.4 for FX60 and FX600, and 82.7±4.1 vs. 83.6±3.8 for FX80 vs. FX800; creatinine similar 78.2±5.6 vs. 77.8±4.6 y 77.1±5.4 vs. 78.1±4.9; β₂-microglobulin 82.2±4.3 vs. 82.9±4.2, and 82.9±4.7 vs. 84.0±3.8; myoglobin 71.0±10 vs. 70.2±9 and 72.8±11 vs. 75.0±10; prolactin 70.4±9 vs. 68.1±9, and 72.2±10 vs. 73.4±8.2; and α₁-microglobulin 22.9±10 vs. 21.6±10, and 26.5±12 vs. 28.8±11, respectively.

CONCLUSION

The increase in the inner diameter of the hollow fibres did not result in improved convective volume and removal capacity.

Clinical Evaluation of Internal Hemodiafiltration (iHDF): A Diffusive-Convective Technique Performed with Internal Filtration Enhanced High-Flux Dialyzers

Aim

Efficiency in removing middle molecules such as ß2-microglobulin (ß2-MG) is one of the main purposes of modern dialytic therapy. In order to achieve this, techniques requiring complex machines and substitution fluid have been developed over recent years. Alternatively, the internal filtration / back filtration phenomenon can be used. The recent development of a so-called “internal filtration enhanced dialyser” prompted us to compare the removal of ß2-MG together with other small molecules when the dialyser was used either in standard hemodiafiltration (HDF) or internal hemodiafiltration (iHDF).

Methods

Ten stable, anuric, hemodialysis (HD) patients treated by thrice weekly standard bicarbonate HD using low-flux synthetic membrane entered the study. A new high-flux polysulfone dialyser designed with the specific aim of enhancing internal filtration (BS-1.6 UL, 1.6 m2, Toray Industries) was used. Post dilution HDF (2.5 l/hour of substitution fluid, dialysate flow 500 ml/min) was compared with iHDF (dialysate flow 750 ml/min), with blood flow at 300 ml/min. Samples were obtained at the start and at the end of the session in order to measure the % removal of urea, creatinine, uric acid, phosphate and ß2-MG (corrected for total protein concentration). In addition, after 20 min of dialysis the clearances of the same molecules were measured. A mathematical model has been developed for the description of the hydrodynamic phenomena taking place within the dialyser and of fluid filtration across the membrane.

Results

No significant differences have been observed in removal rate switching from HDF to iHDF except for ß2-MG removal, which was slightly higher in HDF than in iHDF. Phosphate clearance is significantly higher than those obtained with creatinine in both HDF (p<0.005) and iHDF (p<0.01) modalities. The total convection calculated with the model is reduced with respect to HDF only by 24% (4100 ml/h vs. 5400 ml/h on the average).

Conclusions

iHDF is a high flux dialysis method, which, if performed with a dialyser designed to enhance internal filtration, obtains a much higher removal rate in comparison with dialysers in traditional high flux dialysis, as previously reported in the literature. Provided that the dialyser is used on a dialysis machine working with ultra pure dialysate and UF control, this dialyser line can perform reliable internal HDF without the need for replacement solution. Considering the narrow difference in performance observed between iHDF and HDF, and the increasing number (and age) of patients leading to higher dialysis costs, iHDF represents a cost-effective alternative to other diffusive-convective techniques.

Biochemical and Clinical Impact of Organic Uremic Retention Solutes: A Comprehensive Update

In this narrative review, the biological/biochemical impact (toxicity) of a large array of known individual uremic retention solutes and groups of solutes is summarized. We classified these compounds along their physico-chemical characteristics as small water-soluble compounds or groups, protein bound compounds and middle molecules. All but one solute (glomerulopressin) affected at least one mechanism with the potential to contribute to the uremic syndrome. In general, several mechanisms were influenced for each individual solute or group of solutes, with some impacting up to 7 different biological systems of the 11 considered. The inflammatory, cardio-vascular and fibrogenic systems were those most frequently affected and they are one by one major actors in the high morbidity and mortality of CKD but also the mechanisms that have most frequently been studied. A scoring system was built with the intention to classify the reviewed compounds according to the experimental evidence of their toxicity (number of systems affected) and overall experimental and clinical evidence. Among the highest globally scoring solutes were 3 small water-soluble compounds [asymmetric dimethylarginine (ADMA); trimethylamine-N-oxide (TMAO); uric acid], 6 protein bound compounds or groups of protein bound compounds [advanced glycation end products (AGEs); p-cresyl sulfate; indoxyl sulfate; indole acetic acid; the kynurenines; phenyl acetic acid;] and 3 middle molecules [β₂-microglobulin; ghrelin; parathyroid hormone). In general, more experimental data were provided for the protein bound molecules but for almost half of them clinical evidence was missing in spite of robust experimental data. The picture emanating is one of a complex disorder, where multiple factors contribute to a multisystem complication profile, so that it seems of not much use to pursue a decrease of concentration of a single compound.

Precise Quantitative Assessment of the Clinical Performances of Two High-Flux Polysulfone Hemodialyzers in Hemodialysis: Validation of a Blood-Based Simple Kinetic Model Versus Direct Dialysis Quantification

Highly permeable dialysis membranes with better design filters have contributed to improved solute removal and dialysis efficacy. However, solute membrane permeability needs to be well controlled to avoid increased loss of albumin that is considered to be detrimental for dialysis patients. A novel high-flux dialyzer type (FX CorDiax; Fresenius Medical Care) incorporating an advanced polysulfone membrane modified with nano-controlled spinning technology to enhance the elimination of a broader spectrum of uremic toxins has been released. The aim of this study was to compare in the clinical setting two dialyzer types having the same surface area, the current (FX dialyzer) and the new dialyzer generation (FX CorDiax), with respect to solute removal capacity over a broad spectrum of markers, including assessment of albumin loss based on a direct dialysis quantification method. We performed a crossover study following an A1-B-A2 design involving 10 patients. Phase A1 was 1 week of thrice-weekly bicarbonate hemodialysis with the FX dialyzer, 4 h per treatment; phase B was performed with a similar treatment regimen but with a new FX CorDiax dialyzer and finally the phase A2 was repeated with FX dialyzer as the former phase. Solute removal markers of interest were assessed from blood samples taken before and after treatment and from total spent dialysate collection (direct dialysis quantification) permitting a mass transfer calculation (mg/session into total spent dialysate/ultrafiltrate). On the blood side, there were no significant differences in the solute percent reduction between FX CorDiax 80 and FX 80. On the dialysate side, no difference was observed regarding eliminated mass of different solutes including β₂ -microglobulin (143.1 ± 33.6 vs. 138.3 ± 41.9 mg, P = 0.8), while the solute mass removal of total protein (1.65 ± 0.51 vs. 2.14 ± 0.75 g, P = 0.04), and albumin (0.41 ± 0.21 vs. 1.22 ± 0.51 g, P < 0.001) were significantly less for FX CorDiax 80 compared to the FX 80 dialyzer. The results of this cross-over study indicate that the new FX CorDiax dialyzer has highly effective removal of middle molecules, without any concomitant increase in total protein and albumin loss. The clinical relevance and potential benefit of this finding needs to be determined.

Increasing Haemodialytic Clearances as Residual Renal Function Declines: An Incremental Approach

Many patients with chronic kidney disease start undergoing thrice-weekly haemodialysis (HD), aiming for an HD sessional dialyzer urea clearance target, irrespective of whether they have residual renal function (RRF). While increasing sessional dialyzer urea clearance above a target of 1.2 has not been shown to improve patient survival, it has been shown that the preservation of RRF improves patient self-reported outcomes and survival. Observational studies have suggested that initiating twice-weekly HD schedules leads to greater preservation of RRF. This has led to the concept of following an incremental approach to initiating HD, steadily increasing the amount of weekly dialyzer clearance as RRF decreases. Incremental dialysis practice requires the regular assessment of RRF to prevent inadequate delivery of dialysis treatment. Once RRF is lost, then the dialysis schedule and modality need to be adjusted to try to increase the middle-sized solute clearance and protein-bound toxins.

[Online hemodiafiltration: Practical aspects, safety and efficacy]

Purification of high molecular uremic toxins by conventional hemodialysis is limited. It remains associated with a high morbidity and excessively high mortality. Online hemodiafiltration using a high permeability hemodiafilter, an ultrapure dialysate, and which tends to maximize substitution volumes, provides a high efficiency and low bio-incompatibility renal supplementation. Regular use of online hemodiafiltration is associated with reduced morbidity (reduction of intradialytic hypotension episodes, improved blood pressure control, reduced inflammatory profile, better anemia correction and prevention of β₂-microglobulin-associated amyloidosis). Recently, several cohort studies have shown that hemodiafiltration with high substitution volume was associated with a significant reduction in mortality. Randomized studies have been conducted in Europe to confirm these facts. The high safety of online hemodiafiltration has been confirmed in clinical practice by prospective studies. Online hemodiafiltration has reached its full maturity phase and is expected to represent the new standard of renal replacement therapy.

Effect of Treatment Duration and Frequency on Uremic Solute Kinetics, Clearances and Concentrations

The kinetics of uremic solute clearances are discussed based on two categories of uremic solutes, namely those that are and those that are not derived directly from nutrient intake, particularly dietary protein intake. This review highlights dialysis treatments that are more frequent and longer (high-dose hemodialysis) than conventional thrice weekly therapy. It is proposed that the dialysis dose measures based on urea as a marker uremic solute, such as Kt/V and stdKt/V, be referred to as measures of dialysis inadequacy, not dialysis adequacy. For uremic solutes derived directly from nutrient intake, it is suggested that inorganic phosphorus and protein-bound uremic solutes be considered as markers in the development of alternative measures of dialysis dose for high-dose hemodialysis prescriptions. As the current gap in understanding the detailed kinetics of protein-bound uremic solutes, it is proposed that normalization of serum phosphorus concentration with a minimum (or preferably without a) need for oral-phosphorus binders be targeted as a measure of dialysis adequacy in high-dose hemodialysis. For large uremic solutes not derived directly from nutrient intake (middle molecules), use of extracorporeal clearances for β₂ -microglobulin that are higher than currently available during thrice weekly therapy is unlikely to reduce predialysis serum β₂ -microglobulin concentrations. High-dose hemodialysis prescriptions will lead to reductions in predialysis serum β₂ -microglobulin concentrations, but such reductions are also limited by significant residual kidney clearance. Kinetic data regarding middle molecules larger than β₂ -microglobulin are scarce; additional studies on such uremic solutes are of high interest to better understand improved methods for prescribing high-dose hemodialysis prescriptions to improve patient outcomes.

Are all Dialyzers Compatible with the Convective Volumes Suggested for Postdilution Online Hemodiafiltration?

Introduction

The recent analysis of 4 randomized controlled trials has confirmed the lower mortality risk for postdilution online hemodiafiltration (OL-HDF) compared to hemodialysis, and above all for patients with the highest delivered body surface area standardized convective volume (CV/BSA >23 L/1.73 m2/session). Since the impact of the dialyzers used in these trials has never been studied, we retrospectively analyzed clinical tests carried out with 19 commonly used dialyzers. The aim was to provide information on their performances and behavior to aid in an objective choice for therapies associated with OL-HDF.

Methods

“Efficiency” was evaluated by measuring the reduction ratio of beta-2 microglobulin (RRß2M) and myoglobin (RRmyo) for a CV/BSA between 0 and 30 L, extrapolating them at CV/BSA = 23 L “Safety” was defined by the safe CV (CVsafe), corresponding to the CV/BSA above which albumin loss is >5 g/session. Results: With CV/BSA = 23 L, all the dialyzers ensure an optimal ß2M extraction (RRß2M: 76%–84.5%). For myoglobin, efficiency disparities are bigger (RRmyo: 40%–85%). Above all, 4/19 dialyzers lose more than 5 g albumin and should not be used under these conditions.

Conclusions

It is recommended to prescribe dialyzers that are above all safe. Moreover, if one considers that the removal of middle molecule solutes prevails over the CV necessary for their transmembrane transport, some dialyzers that are more efficient with CV/BSA <23 L than others with CV/BSA >= 23 L might then be prescribed when the conditions do not permit the suggested CV/BSA goal to be achieved.

Determination of Etelcalcetide Biotransformation and Hemodialysis Kinetics to Guide the Timing of Its Dosing

Introduction

Etelcalcetide, a novel calcimimetic agonist of the calcium-sensing receptor for treatment of secondary hyperparathyroidism in chronic kidney disease patients on hemodialysis, is a d-amino acid linear heptapeptide with a d-cysteine that is linked to an l-cysteine by a disulfide bond. In addition to binding to the calcium-sensing receptor, etelcalcetide is biotransformed by disulfide exchange in whole blood to predominantly form a covalent serum albumin peptide conjugate (SAPC). Key factors anticipated to affect the pharmacokinetics and disposition of etelcalcetide in chronic kidney disease patients on hemodialysis are the drug’s intrinsic dialytic properties and biotransformation kinetics.

Methods

These factors were investigated using in vitro methods, and the findings were modeled to derive corresponding kinetic rate constants.

Results

Biotransformation was reversible after incubation of etelcalcetide or SAPC in human whole blood. The rate of SAPC formation from etelcalcetide was 18-fold faster than the reverse process. Clearance of etelcalcetide by hemodialysis was rapid in the absence of blood and when hemodialysis was initiated immediately after addition of etelcalcetide to blood. Preincubation of etelcalcetide in blood for 3 hours before hemodialysis resulted in formation of SAPC and decreased its clearance due to the slow rate of etelcalcetide formation from SAPC. Etelcalcetide hemodialysis clearance was >16-fold faster than its biotransformation.

Discussion

These results indicate that etelcalcetide should be administered after hemodialysis to avoid elimination of a significant fraction of the dose.

The Relationship Between Hemodialysis Modality and Insulin Resistance in Non-Diabetic Hemodialysis Patients

Background: Although various modalities of hemodialysis (HD) are presumed to have different effects on insulin resistance (IR), the relationship between hemodiafiltration (HDF) and IR has not been fully evaluated. Methods: In a cross-sectional study, 82 non-diabetic HD patients were enrolled. The patients were divided into two groups according to the median homeostasis model assessment index (HOMA-IR) value of 1.685. Clinical and biochemical data were compared, and multivariate logistic regression analysis was performed to identify the independent factors associated with higher HOMA-IR. Results: The higher HOMA-IR group had increased body mass index (BMI), decreased HDL cholesterol, and lower beta-2 microglobulin reduction rate (β2-MG RR) compared to the lower HOMA-IR group. HOMA-IR was significantly correlated with β2-MG RR. In addition, HDF patients had lower HOMA-IR levels compared with low flux hemodialysis patients. On multivariate logistic regression analysis, BMI and HDF treatment were independent factors associated with higher and lower HOMA-IR, respectively. Conclusion: This study suggests that HDF treatment may reduce IR in non-diabetic HD patients.

The incremental treatment of ESRD: a low-protein diet combined with weekly hemodialysis may be beneficial for selected patients

BACKGROUND

Infrequent dialysis, namely once-a-week session combined with very low-protein, low-phosphorus diet supplemented with ketoacids was reported as a useful treatment schedule for ESRD patients with markedly reduced residual renal function but preserved urine output. This study reports our findings from the application of a weekly dialysis schedule plus less severe protein restriction (standard low-protein low-phosphorus diet) in stage 5 CKD patients with consistent dietary discipline.

METHODS

This is a multicenter, prospective controlled study, including 68 incident CKD patients followed in a pre-dialysis clinic with Glomerular Filtration Rate 5 to 10 ml/min/1.73/ m2 who became unstable on the only medical treatment. They were offered to begin a Combined Diet Dialysis Program (CDDP) or a standard thrice-a-week hemodialysis (THD): 38 patients joined the CDDP, whereas 30 patients chose THD. Patients were studied at baseline, 6 and 12 months; hospitalization and survival rate were followed-up for 24 months.

RESULTS

Volume output and residual renal function were maintained in the CDDP Group while those features dropped quickly in THD Group. Throughout the study, CDDP patients had a lower erythropoietin resistance index, lower β2 microglobulin levels and lower need for cinacalcet of phosphate binders than THD, and stable parameters of nutritional status. At 24 month follow-up, 39.4% of patients were still on CDDP; survival rates were 94.7% and 86.8% for CDDP and THD patients, respectively, but hospitalization rate was much higher in THD than in CDDP patients. The cost per patient per year resulted significantly lower in CDDP than in THD Group.

CONCLUSIONS

This study shows that a CDDP served to protect the residual renal function, to maintain urine volume output and to preserve a good nutritional status. CDDP also blunted the rapid β2 microglobulin increase and resulted in better control of anemia and calcium-phosphate abnormalities. CDDP was also associated with a lower hospitalization rate and reduced need of erythropoietin, as well as of drugs used for treatment of calcium-phosphate abnormalities, thus leading to a significant cost-saving. We concluded that in selected ESRD patients with preserved urine output attitude to protein restriction, CDDP may be a beneficial choice for an incremental hemodialysis program.

Salvage of severe ischemic lower limb having peak creatine phosphokinase level exceeding 200,000 IU/L treated by continuous hemodiafiltration

We performed revascularization by an anti-anatomical bypass in a 40-year-old man with extended ischemia of both legs beyond 12 hr after onset because of traumatic aortic dissection. This patient developed myonephropathic metabolic syndrome, including renal and circulatory failure accompanied by a creatine phosphokinase level above 200,000 IU/L. Nevertheless, his bilateral affected limbs were salvaged by intensive care based on aggressive hemocatharsis with continuous hemodiafiltration with treatment for poor hemodynamics and respiratory distress.

Principles and operational parameters to optimize poison removal with extracorporeal treatments

A role for nephrologists in the management of a poisoned patient involves evaluating the indications for, and methods of, enhancing the elimination of a poison. Nephrologists are familiar with the various extracorporeal treatments (ECTRs) used in the management of impaired kidney function, and their respective advantages and disadvantages. However, these same skills and knowledge may not always be considered, or applicable, when prescribing ECTR for the treatment of a poisoned patient. Maximizing solute elimination is a key aim of such treatments, perhaps more so than in the treatment of uremia, because ECTR has the potential to reverse clinical toxicity and shorten the duration of poisoning. This manuscript reviews the various principles that govern poison elimination by ECTR (diffusion, convection, adsorption, and centrifugation) and how components of the ECTR can be adjusted to maximize clearance. Data supporting these recommendations will be presented, whenever available.

A stepwise approach for the management of poisoning with extracorporeal treatments

The use of an extracorporeal treatment (ECTR) in a poisoned patient may be life-saving in a limited number of scenarios. The decision-processes surrounding the use of ECTR in poisoning is complex: most nephrologists are not trained to assess a poisoned patient while clinical toxicologists rarely prescribe ECTRs. Deciding on which ECTR is most appropriate for a poison requires a good understanding of the poison's physicochemical and pharmacokinetic properties. Further, a detailed understanding of the capabilities and limitations of the different ECTRs can be useful to select the most appropriate ECTR for a given clinical situation. This manuscript provides a stepwise approach to assess the usefulness of ECTRs in poisoning.

Available extracorporeal treatments for poisoning: overview and limitations

Poisoning is a significant public health problem. In severe cases, extracorporeal treatments (ECTRs) may be required to prevent or reverse major toxicity. Available ECTRs include intermittent hemodialysis, sustained low-efficiency dialysis, intermittent hemofiltration and hemodiafiltration, continuous renal replacement therapy, hemoperfusion, therapeutic plasma exchange, exchange transfusion, peritoneal dialysis, albumin dialysis, cerebrospinal fluid exchange, and extracorporeal life support. The aim of this article was to provide an overview of the technical aspects, as well as the potential indications and limitations of the different ECTRs used for poisoned patients.

Monitoring of hemodialysis quality-of-care indicators: why is it important?

BACKGROUND

Meeting specific guideline targets is associated with improved survival rates and reduced hospitalizations in the dialysis population. This prospective work evaluated the adequacy of hemodialysis quality indicators in an in-center hemodialysis population with severe comorbidities, and assessed whether clinical practice could impact intermediate outcomes.

METHODS

All the chronic hemodialysis patients treated in Rouen University Hospital hemodialysis Unit between January 2009 and April 2010 were included in this observational study. Every quarter, mean levels and prevalence of conformity were collected for the following indicators: anemia, dialysis dose, serum calcium and phosphorus, PTH, 25OH-vitamin D, albumin, serum bicarbonate, LDL-cholesterol, serum β2-microglobulin, systolic and diastolic blood pressure, intradialytic hypotension and vascular access. Conformity of quality-of-care indicators was determined according to targets defined by international guidelines, whenever available.

RESULTS

Altogether, 124 patients were included in the study. Thirty-three patients were evaluated during the entire follow-up period. An improvement in the percentage of conformity was observed for hemoglobin, dialysis dose, phosphates, PTH, serum bicarbonate and β2-microglobulin in the global population. Failure to improve conformity rates for several indicators, including serum albumin, was found, possibly depending on patients' comorbidities rather than on quality of care.

CONCLUSION

Overall, this study shows that following quality-of-care indicators can improve clinical practice by identifying center-specific weaknesses, prompting the establishment of corrective measures. Finally, we suggest that the definition and targets of some indicators, especially hypertension and LDL-cholesterol, be reviewed, since evidence of their association with mortality is not demonstrated.

Thermodilution versus Saline Dilution Method for Vascular Access Blood Flow Measurement in High-Flux and On-Line Hemodiafiltration

Purpose

Access blood flow (Qa) measurements are one of the most important components in vascular access monitoring programs, even though these indirect methods have only been validated with high-flux hemodialysis (HF; pump flow [Qb] 300 mL/min). This study was to assess the utility from thermodilution (BTM) with respect to the saline dilution method (SDM) in HF and on-line hemodiafiltration (OL-HDF) with routinely prescribed parameters in comparison with validation conditions.

Methods

Three consecutive sessions were assessed in 31 hemodialysis patients (27AVF). The Bland-Altman method and Lin's concordance coefficient (ρc) were used to study accuracy and precision. We used the student t test for the analysis of Qa-value in the different subgroups.

Results

In HF-hemodialysis 1 (Qb 300 mL/min), Qa was 1109 ± 541 mL/min SDMa and 1213 ± 639 mL/min BTM (P=.993a; bias 103.7 mL/min and ρc 0.78). In HF-hemodialysis 2 (Qb 420 mL/min) Qa 1071 ± 578 mL/min SDM (P=1.0a; -38.2 mL/min and 0.96) and 1216 ± 667 mL/min BTM (P=.992a; 127.3 mL/min and 0.70). In OL-HDF hemodialysis 3 (Qb 420 mL/min) Qa 1071 ± 510 mL/min SDM (P=1.0a; -48.4 mL/min and 0.96) and 1219 ± 580 mL/min BTM (P=.977a; 99.2 mL/min and 0.75). Statistically significant differences were only obtained in patients aged ≥ 65 years old (P=.016) and peripheral vascular disease (P=.007).

Conclusions

Our results demonstrate how the saline dilution method was more accurate than thermodilution in the HF and OL-HDF modalities with routinely prescribed parameters. Finally, in this study, advanced age (>65 years old) and peripheral vascular disease were associated with a significantly lower Qa-value.