Optimal convection volume for improving patient outcomes in an international incident dialysis cohort treated with online hemodiafiltration

Hemodialysis Procedures for Stable Incident and Prevalent Patients Optimize Hemodynamic Stability, Dialysis Dose, Electrolytes, and Fluid Balance

The demographic profile of patients transitioning from chronic kidney disease to kidney replacement therapy is changing, with a higher prevalence of aging patients with multiple comorbidities such as diabetes mellitus and heart failure. Cardiovascular disease remains the leading cause of mortality in this population, exacerbated by the cardiovascular stress imposed by the HD procedure. The first year after transitioning to hemodialysis is associated with increased risks of hospitalization and mortality, particularly within the first 90-120 days, with greater vulnerability observed among the elderly. Based on data from clinics in Fresenius Medical Care Europe, Middle East, and Africa NephroCare, this review aims to optimize hemodialysis procedures to reduce mortality risk in stable incident and prevalent patients. It addresses critical aspects such as treatment duration, frequency, choice of dialysis membrane, dialysate composition, blood and dialysate flow rates, electrolyte composition, temperature control, target weight management, dialysis adequacy, and additional protocols, with a focus on mitigating prevalent intradialytic complications, particularly intradialytic hypotension prevention.

High volume online hemodiafiltration: a global perspective and the Brazilian experience

Online hemodiafiltration (HDF) is a rapidly growing dialysis modality worldwide. In Brazil, the number of patients with private health insurance undergoing HDF has exceeded the number of patients on peritoneal dialysis. The achievement of a high convection volume was associated with better clinical imprand patient - reported outcomes confirming the benefits of HDF. The HDFit trial provided relevant practical information on the implementation of online HDF in dialysis centers in Brazil. This article aims to disseminate technical information to improve the quality and safety of this new dialysis modality.

Latest Trends in Hemodiafiltration

This review provides a detailed analysis of hemodiafiltration (HDF), its progress from an emerging technique to a potential conventional treatment for chronic hemodialysis patients, and its current status. The article covers the advances, methods, and clinical benefits of HDF, specifically focusing on its impact on cardiovascular health, survival rates, and overall well-being. The review also addresses questions about the safety of HDF and provides evidence to dispel concerns related to the elimination of beneficial substances and infection risks. Additionally, the article explores the potential implications of expanded hemodialysis (HDx) as an alternative to HDF, its classification, safety profile, and an ongoing trial assessing its non-inferiority to HDF. Supported by evidence from randomized controlled trials and observational studies, the review emphasizes the superiority of HDF as a hemodialysis modality and advocates for its positioning as the gold standard in treatment. However, it acknowledges the need for extensive research to define the role of HDx in comprehensive treatment approaches in individuals undergoing dialysis. The synthesis of current knowledge underscores the importance of ongoing exploration and research to refine hemodialysis practices for optimal patient outcomes.

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.

Unveiling the Clinical Benefits of High-Volume Hemodiafiltration: Optimizing the Removal of Medium-Weight Uremic Toxins and Beyond

Dialysis treatment has improved the survival of patients with kidney failure. However, the hospitalization and mortality rates remain alarmingly high, primarily due to incomplete uremic toxin elimination. High-volume hemodiafiltration (HDF) has emerged as a promising approach that significantly improves patient outcomes by effectively eliminating medium and large uremic toxins, which explains its increasing adoption, particularly in Europe and Japan. Interest in this therapy has grown following the findings of the recently published CONVINCE study, as well as the need to understand the mechanisms behind the benefits. This comprehensive review aims to enhance the scientific understanding by explaining the underlying physiological mechanisms that contribute to the positive effects of HDF in terms of short-term benefits, like hemodynamic tolerance and cardiovascular disease. Additionally, it explores the rationale behind the medium-term clinical benefits, including phosphorus removal, the modulation of inflammation and oxidative stress, anemia management, immune response modulation, nutritional effects, the mitigation of bone disorders, neuropathy relief, and amyloidosis reduction. This review also analyzes the impact of HDF on patient-reported outcomes and mortality. Considering the importance of applying personalized uremic toxin removal strategies tailored to the unique needs of each patient, high-volume HDF appears to be the most effective treatment to date for patients with renal failure. This justifies the need to prioritize its application in clinical practice, initially focusing on the groups with the greatest potential benefits and subsequently extending its use to a larger number of patients.

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.

Why should we focus on high-volume hemodiafiltration?

Though noticeable technological advances related to hemodialysis (HD) have been made, unfortunately, the survival rate of dialysis patients has yet to improve significantly. However, recent research findings reveal that online hemodiafiltration (HDF) significantly improves patient survival in comparison to conventional HD. Accordingly, the number of patients receiving online HDF is increasing. Although the mechanism driving the benefit has not yet been fully elucidated, survival advantages are mainly related to the lowering of cardiovascular mortality. High cardiovascular mortality among HD patients is seemingly attributable to the cardiovascular changes that occur in response to renal dysfunction and the HD-induced myocardial stress and injury, and online HDF appears to improve such secondary cardiovascular changes. Interestingly, patient survival improves only if the convection volume is supplied sufficiently over a certain level during online HDF treatment. In other words, survival improvement from online HDF is related to convection volume. Therefore, there is a growing interest in high-volume HDF in terms of improving the survival rate. The survival improvement will require a minimum convection volume of 23 L or more per 4-hour session for postdilution HDF. To obtain an optimal high convection volume in online HDF, several factors, such as the treatment time, blood flow rate, filtration fraction, and dialyzer, need to be considered. High-volume HDF can be performed easily and safely in routine clinical practice. Therefore, when the required equipment is available, performing high-volume HDF will help to improve the survival rate of dialysis patients.

Sustainability and environmental impact of on-line hemodiafiltration

Environment has become a main issue of human activities. Chronic hemodialysis (HD) therapy saves lives but consumes large amounts of water and power and produces a lot of care-related waste. On-line hemodiafiltration (HDF) improves patients' outcomes but increases water consumption from ultra-pure water needs and infusion volume. New-generation water treatment systems have much reduced the proportion of reject water that can also be reused. Reducing the dialysate flow in standard HD decreases significantly the water consumption but impacts negatively dialysis efficiency. When on-line HDF is prescribed, reducing the dialysate flow may be applied to decrease water needs while maintaining dialysis efficiency. Nowadays, dialysis prescription cannot ignore its impact on natural resources and environment.

Hemodiafiltration outcomes in special situations

This Seminars in Dialysis Hemodiafiltration Symposium includes many references regarding the outcomes of this modality in general. The results in special populations are included in some of the studies, but have not been compared in a systematic manner. The purpose of this review is to compile those outcome results in select populations.

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.

Informed decision-making in delivery of dialysis: combining clinical outcomes with sustainability

As the prevalence of chronic kidney disease is expected to rise worldwide over the next decades, provision of renal replacement therapy (RRT), will further challenge budgets of all healthcare systems. Most patients today requiring RRT are treated with haemodialysis (HD) therapy and are elderly. This article demonstrates the interdependence of clinical and sustainability criteria that need to be considered to prepare for the future challenges of delivering dialysis to all patients in need. Newer, more sustainable models of high-value care need to be devised, whereby delivery of dialysis is based on value-based healthcare (VBHC) principles, i.e. improving patient outcomes while restricting costs. Essentially, this entails maximizing patient outcomes per amount of money spent or available. To bring such a meaningful change, revised strategies having the involvement of multiple stakeholders (i.e. patients, providers, payers and policymakers) need to be adopted. Although each stakeholder has a vested interest in the value agenda often with conflicting expectations and motivations (or motives) between each other, progress is only achieved if the multiple blocs of the delivery system are advanced as mutually reinforcing entities. Clinical considerations of delivery of dialysis need to be based on the entire patient disease pathway and evidence-based medicine, while the non-clinical sustainability criteria entail, in addition to economics, the societal and ecological implications of HD therapy. We discuss how selection of appropriate modes and features of delivery of HD (e.g. treatment modalities and schedules, selection of consumables, product life cycle assessment) could positively impact decision-making towards value-based renal care. Although the delivery of HD therapy is multifactorial and complex, applying cost-effectiveness analyses for the different HD modalities (conventional in-centre and home HD) can support in guiding payability (balance between clinical value and costs) for health systems. For a resource intensive therapy like HD, concerted and fully integrated care strategies need to be urgently implemented to cope with the global demand and burden of HD therapy.

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.

Randomized comparison of three high-flux dialyzers during high-volume online hemodiafiltration—the comPERFORM study

Background

Dialyzers should be designed to efficiently eliminate uraemic toxins during dialysis treatment, given that the accumulation of small and middle molecular weight uraemic solutes is associated with increased mortality risk of patients with end-stage renal disease. In the present study we investigated the novel FX CorAL dialyzer with a modified membrane surface for performance during online hemodiafiltration (HDF) in a clinical setting.

Methods

comPERFORM was a prospective, open, controlled, multicentric, interventional, crossover study with randomized treatment sequences. It randomized stable patients receiving regular post-dilution online HDF to FX CorAL 600 (Fresenius Medical Care Deutschland), xevonta Hi 15 (B. Braun) and ELISIO 150H (Nipro) each for 1 week. The primary outcome was β2-m removal rate (β2-m RR) during online HDF. Secondary endpoints were RR and/or clearance of β2-m and other molecules. Albumin removal over time was an exploratory endpoint. Non-inferiority and superiority of FX CorAL 600 versus comparators were tested.

Results

Fifty-two patients were included and analysed. FX CorAL 600 showed the highest β2-m RR (75.47%), followed by xevonta Hi 15 (74.01%) and ELISIO 150H (72.70%). Superiority to its comparators was statistically significant (P = 0.0216 and P < 0.0001, respectively). Secondary endpoints related to middle molecules affirmed these results. FX CorAL 600 demonstrated the lowest albumin removal up to 60 minutes and its sieving properties changed less over time than with comparators.

Conclusions

FX CorAL 600 efficiently removed middle and small molecules and was superior to the two comparators in β2-m RR. Albumin sieving kinetics point to reduced formation of a secondary membrane.

Development of online hemodiafiltration in Japan

Evidence concerning online hemodiafiltration (ol-HDF) includes increased uremic toxin removal, prevention of dialysis-related hypotension, improved survival, and recovery of dialysis-related uncertain symptoms. In particular, evidence has been shown regarding prevention of dialysis hypotension and improvement of survival, but the mechanism of its manifestation is still unclear and its effects themselves are questionable. In Japan, pre dilution ol-HDF is mainly performed, and improvement in survival rate has been shown on the condition of convection volume is 40 L/session or more. In particular, the removal of α1-microglubulin (αMG), which is a medium-middle solute, is targeted. The antioxidant action (Heme Scavenger) of αMG, is presumed, but in dialysis patients, the majority in serum are deteriorated (oxidized) αMG. It has been pointed out that removing the deteriorated αMG by ol-HDF may produce new αMG from the liver and lead to recovery of the original antioxidant effect. However, clinical evidence of this mechanism is desired. Obtaining evidence for the indicated αMG removal activity of ol-HDF will lead to advancement in HDF.

Mixed versus predilution hemodiafiltration effects on convection volume and small and middle molecule clearance in hemodialysis patients: a prospective randomized controlled trial

Background

The use of newly developed mixed-dilution hemodiafiltration (HDF) can supplement the weaknesses of pre- and postdilution HDF. However, it is unclear whether mixed-HDF performs well compared to predilution HDF.

Methods

We conducted a prospective, open-labeled, randomized controlled trial from two hemodialysis centers in Korea. Between January 2017 and September 2019, 60 patients who underwent chronic hemodialysis were randomly assigned at a 1:1 ratio to receive either predilution HDF (n = 30) or mixed-HDF (n = 30) for 6 months. We compared convection volume, changes in small- and medium-sized molecule clearance, high-sensitive C-reactive protein (hs-CRP) level, and dialysis-related parameters between the two dialysis modalities.

Results

A mean effective convection volume of 41.0 ± 10.3 L/session in the predilution HDF group and 51.5 ± 9.0 L/session in the mixed-HDF group was obtained by averaging values of three time-points. The difference in effective convection volume between the groups was 10.5 ± 1.3 L/session. This met the preset noninferiority criteria, suggesting that mixed-HDF was noninferior to predilution HDF. Moreover, the β2-microglobulin reduction rate was greater in the mixed-HDF group than in the predilution HDF group, while mixed-HDF provided greater transmembrane pressure. There were no significant between-group differences in Kt/V urea levels, changes in predialysis hs-CRP levels, proportions of overhydration, or blood pressure values. Symptomatic intradialytic hypotension episodes and other adverse events occurred similarly in the two groups.

Conclusion

Use of mixed-HDF was comparable to predilution HDF in terms of delivered convection volume and clinical parameters. Moreover, mixed-HDF provided better β2-microglobulin clearance than predilution HDF.

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.

Influence of Dialysis Modality on the Treatment of Anemia in Patients with End-Stage Kidney Disease

Anemia is a common complication among the patients with end-stage kidney disease. Management of anemia is influenced by several factors: iron deficiency, subtherapeutic dosage of erythropoietin, microinflammation, vitamin D deficiency, increased iPTH levels and inadequate hemodialysis.

The aim of the study was to examine impact of dialysis modality on blood hemoglobin level as well as status of iron, status of vitamin D, hemodialysis adequacy and erythropoietin dose.

The study included 120 patients which were divided into two groups: the group of patients treated with hemodiafiltration and the group of patients treated with standard hemo-dialysis. For statistical analysis Kolmogorov-Smirnov test, Student’s t-test and Mann-Whitney U-test were used.

Blood hemoglobin level and parameters of hemodialysis adequacy (Kt/V index, spKt/V index, URR index), hematocrit ad protein catabolic rate (nPCR) were statisticaly significant lower in patients treated with regular hemodialysis compared to patients treated with regular hemodiafiltration. Serum ferritin level, C-reactive protein level and average monthly dose of intravenous iron were higher in the patients treated with regular hemodialysis compared to patients treated with hemodiafiltration.

Patients treated with hemodiafiltration have lower grade of microinflammation, better iron status and better control of anemia compared to the patients treated with regular hemodialysis. Dialysis modality is an important factor that influences management of anemia in the patients with end-stage kidney disease.

Achieving high convective volume in hemodiafiltration: Lessons learned after successful implementation in the HDFit trial

BACKGROUND AND OBJECTIVES

High-volume online hemodiafiltration (OL-HDF) associates with improved outcomes compared to hemodialysis (HD), provided adequate dosing is achieved as estimated from convective volume (CV). Achievement of high CV and its impact on biochemical indicators following a standardized protocol converting HD patients to OL-HDF has not been systematically reported. We assessed the success of implementation of OL-HDF in clinics naïve to the modality.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

We analyzed the results of the implementation of postdilution OL-HDF in patients randomized to the HDF arm of a clinical trial (impact of hemoDiaFIlTration on physical activity and self-reported outcomes: a randomized controlled trial (HDFit) trial [ClinicalTrials.gov:NCT02787161]). The day before randomization of the first patient to OL-HDF at each clinic staff started a 3-day in-person training module on operation of Fresenius 5008 CorDiax machine in HDF mode. Patients were converted from high-flux HD to OL-HDF under oversight of trainers. OL-HDF was performed over a 6-months follow-up with a CV target of 22 L/treatment. We characterized median achieved CV >22 L/treatment record and analyzed the impact of HDF on biochemical variables.

RESULTS

Ninety-seven patients (mean age 53 ± 16 years, 29% with diabetes, and 11% had a catheter) from 13 clinics randomized to the OL-HDF arm of the trial were converted from HD to HDF. Median CV > 22 L/treatment was achieved in 99% (94/95) of OL-HDF patients throughout follow-up. Monthly mean CV ranged from 27.1 L to 27.5 L. OL-HDF provided an increased single pool Kt/V at 3-months (0.2 [95% CI: 0.1-0.3]) and 6-months (0.2 [95% CI: 0.1-0.4]) compared to baseline, and reduced phosphate at 3-months (-0.4 mg/dL [95% CI: -0.8 to -0.12]) of follow-up.

CONCLUSIONS

High-volume online hemodiafiltration was successfully implemented with 99% of patients achieving protocol defined CV target. Monthly mean CV was consistently >22 L/treatment during follow-up. Kt/V increased, and phosphate decreased with OL-HDF. Findings resulting from a short training period in several dialysis facilities appear to suggest HDF is an easily implementable technique.

Practice Patterns and Outcomes of Online Hemodiafiltration: A Real-World Evidence Study in a Russian Dialysis Network

BACKGROUND

Evidence suggests that online hemodiafiltration (OL-HDF) is associated with improved survival. Whether the dose-response relationship between convective volume and mortality may be confounded by selection bias or descends from practice patterns is not clear. We sought to evaluate the role of patients' characteristics and practice patterns on OL-HDF dose and mortality in a large private dialysis network in the Republic of Russia.

METHODS

In this multicenter, historical cohort study, we included adult incident patients on OL-HDF with at least 90 days of survival on renal replacement therapy in centers belonging to the Russian Federation Fresenius Medical Care network (January 1, 2011, to December 31, 2016). We evaluated predictors and outcomes (survival) of substitution volume target achievement (Qsub > 21 L/session).

RESULTS

Among 1,081 enrolled patients, the average Qsub was 22.9 (±3.2) L/session; the mean ultrafiltration volume was 1.6 (±0.8) L/session. The mean age was 55.8 ± 13.2; 42% were woman. Most common comorbidities were congestive heart failure (39.7%) and peripheral vascular disease (21.7%). The average hemoglobin was 9.3 ± 1.3. The case-mix adjusted center effect accounted for 20% of variance in Qsub. The top 10 most important variables associated with higher Qsub were effective Qb, serum protein, Charlson's comorbidity index, hemoglobin, year of dialysis initiation (proxy of high Qsub treatment policy in the clinic network), predialysis heart rate, serum bicarbonate, serum phosphate, age, serum sodium, and dry body weight. In addition, we found that the association of Qb with Qsub is moderated by year of enrollment, intradialytic weight gain, and coronary artery disease, whereas higher hemoglobin concentration moderated the relationship between treatment time and Qsub. Finally, Qsub between 21 and 25 L/session was associated with longer 5-year survival.

CONCLUSIONS

Both center-dependent clinical practice standards and patient clinical conditions substantially contributed to the risk of low Qsub. We confirmed previous evidence indicating better survival among patients with Qsub ≥ 21 L/session.

On the CO2 gain in on-line hemodiafiltration

BACKGROUND

The dialysis bath holds up to 90 mmHg carbon dioxide (CO₂ ) in order to keep pH low and salts in their soluble forms. CO₂ crosses the dialyzer membrane and diffuses to patients. In post-dilution on-line hemodiafiltration (HDF) many liters of CO₂ -containing dialysis bath - in the form of infusate - are delivered directly to patients bypassing the filtering membrane, but the precise amount of CO₂ delivered is unknown.

METHODS

To gain insights on this issue 18 outpatients undergoing their regular on-line HDF were investigated by means of blood gas analysis.

RESULTS

Arterial pre-dialysis samples show slight hypocapnia (35.40 ± 3.22 mmHg) consistent with the secondary compensatory response to metabolic acidosis. In blood coming back to patients (venous line of extracorporeal circuit) pCO₂ doubled, amounting to 69 ± 5.5 mmHg (P < .0001 with respect to pre-dialysis values) hence in on-line HDF a CO₂ gain does occur. Turning off the infusate flux pump, pCO₂ decreased to 63.1 ± 5.8 mmHg (P = .004) meaning that delivery of infusate in post-dilution mode significantly contributes to CO₂ gain, albeit by a small amount.

CONCLUSION

On-line HDF is featured by CO₂ delivery to patients, in part dragged by the infusate.

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.

Benefits and harms of high-dose haemodiafiltration versus high-flux haemodialysis: the comparison of high-dose haemodiafiltration with high-flux haemodialysis (CONVINCE) trial protocol

INTRODUCTION

End-stage kidney disease (ESKD) is a major public health problem affecting more than 2 million people worldwide. It is one of the most severe chronic non-communicable diseases. Haemodialysis (HD) is the most common therapeutic option but is also associated with a risk of cardiovascular events, hospitalisation and suboptimal quality of life. Over the past decades, haemodiafiltration (HDF) has become available. Although high-dose HDF has shown some promising survival advantage compared to conventional HD, the evidence remains controversial. A Cochrane systematic review found, in low-quality trials, with various convective forms of dialysis, a reduction in cardiovascular, but not all-cause mortality and the effects on non-fatal cardiovascular events and hospitalisation were uncertain. In contrast, an individual patient data analysis suggested that high-dose HDF reduced both all-cause and cardiovascular mortality compared to HD. In view of these discrepant results, a definitive trial is required to determine whether high-dose HDF is preferable to high-flux HD. The comparison of high-dose HDF with high-flux HD (CONVINCE) study will assess the benefits and harms of high-dose HDF versus a conventional high-flux HD in adults with ESKD.

METHODS AND ANALYSIS

This international, prospective, open label, randomised controlled trial aims to recruit 1800 ESKD adults treated with HD in nine European countries. Patients will be randomised 1:1 to high-dose HDF versus continuation of conventional high-flux HD. The primary outcome will be all-cause mortality at 3 years' follow-up. Secondary outcomes will include cause-specific mortality, cardiovascular events, all-cause and infection-related hospitalisations, patient-reported outcomes (eg, health-related quality of life) and cost-effectiveness.

ETHICS AND DISSEMINATION

The CONVINCE study will address the question of benefits and harms of high-dose HDF compared to high-flux HD for kidney replacement therapy in patients with ESKD with a focus on survival, patient perspectives and cost-effectiveness.

TRIAL REGISTRATION NUMBER

Netherlands National Trial Register (NTR 7138).

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.

The effect of high-volume online haemodiafiltration on nutritional status and body composition: the ProtEin Stores prEservaTion (PESET) study

Background

Compared with conventional haemodialysis (HD), online haemodiafiltration (OL-HDF) achieves a more efficient removal of uraemic toxins and reduces inflammation, which could favourably affect nutritional status. We evaluate the effect of OL-HDF on body composition and nutritional status in prevalent high-flux HD (HF-HD) patients.

Methods

In all, 33 adults with chronic kidney disease (CKD) Stage 5 undergoing maintenance HF-HD were assigned to post-dilution OL-HDF (n = 17) or to remain on HF-HD (n = 16, control group) for 12 months. The primary outcome was the change in lean tissue mass (LTM), intracellular water (ICW) and body cell mass (BCM) assessed by multifrequency bioimpedance spectroscopy (BIS) at baseline and 4, 8 and 12 months. The rate of change in these parameters was estimated with linear mixed-effects models.

Results

Compared with OL-HDF, patients assigned to HF-HD experienced a gradual reduction in LTM, ICW and BCM. These differences reached statistical significance at Month 12, with a relative difference of 7.31 kg [95% confidence interval (CI) 2.50-12.11; P = 0.003], 2.32 L (95% CI 0.63-4.01; P = 0.008) and 5.20 kg (95% CI 1.74-8.66; P = 0.004) for LTM, ICW and BCM, respectively. The normalized protein appearance increased in the OL-HDF group compared with the HF-HD group [0.26 g/kg/day (95% CI 0.05-0.47); P = 0.002], with a relative reduction in high-sensitive C-reactive protein [-13.31 mg/dL (95% CI -24.63 to -1.98); P = 0.02] at Month 12.

Conclusions

OL-HDF for 1 year compared with HF-HD preserved muscle mass, increased protein intake and reduced the inflammatory state related to uraemia and dialysis, supporting the hypothesis that high convection volume can benefit nutritional status and prevent protein-energy wasting in HD patients.

Overexposure to Bisphenol A and Its Chlorinated Derivatives of Patients with End-Stage Renal Disease during Online Hemodiafiltration

The health safety conditions governing the practice of online hemodiafiltration (OL-HDF) do not yet incorporate the risks related to the presence of endocrine disruptors such as bisphenol A (BPA). The aim of this study was to assess, for the first time, the exposure to BPA but also to its chlorinated derivatives (ClxBPA) (100 times more estrogenic than BPA) during OL-HDF. We demonstrated that BPA is transmitted by the different medical devices used in OL-HDF: ultrafilters, dialysis concentrate cartridges (and not only dialyzers, as previously described). Moreover, BPA has been found in dialysis water as well as in ultrapure dialysate and replacement fluid due to contamination of water coming from municipal network. Indeed, due to contaminations provided by both ultrafilters and water, high levels of BPA were determined in the infused replacement fluid (1033 ng.L⁻¹) from the beginning of the session. Thus, our results demonstrate that dialysis water must be considered as an important exposure source to endocrine disruptors, especially since other micropollutants such as ClxBPA have also been detected in dialysis fluids. While assessment of the impact of this exposure remains to be done, these new findings should be taken into account to assess exposure risks in end-stage renal disease patients.

Online Hemodiafiltration Inhibits Inflammation-Related Endothelial Dysfunction and Vascular Calcification of Uremic Patients Modulating miR-223 Expression in Plasma Extracellular Vesicles

Decreased inflammation and cardiovascular mortality are evident in patients with end-stage chronic kidney disease treated by online hemodiafiltration. Extracellular vesicles (EV) are mediators of cell-to-cell communication and contain different RNA types. This study investigated whether mixed online hemodiafiltration (mOL-HDF) beneficial effects associate with changes in the RNA content of plasma EV in chronic kidney disease patients. Thirty bicarbonate hemodialysis (BHD) patients were randomized 1:1 to continue BHD or switch to mOL-HDF. Concentration, size, and microRNA content of plasma EV were evaluated for 9 mo; we then studied EV effects on inflammation, angiogenesis, and apoptosis of endothelial cells (HUVEC) and on osteoblast mineralization of vascular smooth muscle cells (VSMC). mOL-HDF treatment reduced different inflammatory markers, including circulating CRP, IL-6, and NGAL. All hemodialysis patients showed higher plasma levels of endothelial-derived EV than healthy subjects, with no significant differences between BHD and mOL-HDF. However, BHD-derived EV had an increased expression of the proatherogenic miR-223 with respect to healthy subjects or mOL-HDF. Compared with EV from healthy subjects, those from hemodialysis patients reduced angiogenesis and increased HUVEC apoptosis and VSMC calcification; however, all these detrimental effects were reduced with mOL-HDF with respect to BHD. Cell transfection with miR-223 mimic or antagomiR proved the role of this microRNA in EV-induced HUVEC and VSMC dysfunction. The switch from BHD to mOL-HDF significantly reduced systemic inflammation and miR-223 expression in plasma EV, thus improving HUVEC angiogenesis and reducing VSMC calcification.

Global prevalent use, trends and practices in haemodiafiltration

Online haemodiafiltration (HDF) represents today the most advanced and innovative form of renal replacement therapy (RRT). Recent controlled trials tend to prove its superiority over conventional haemodialysis on hard clinical end points provided that the right convective dose was delivered. In this article we report on present prevalent use and epidemiologic trends of HDF worldwide as well as on practice patterns in HDF prescription. In addition we analyze factors that may affect HDF clinical acceptance and more widely its implementation. National and international renal registries provide valuable demographic and epidemiologic information on end stage kidney disease patients on RRT. However, the updating and maintenance of such information system is particularly challenging at a country level and even more so on an international basis. Lag time, incompleteness and/or imprecision of data collection may further hamper precision and validity of data reporting. Fresenius Medical Care (FMC), as a large dialysis care provider operating worldwide, maintains an annually updated database addressing international end stage kidney disease data. Over the last decade, FMC has produced series of precise and reliable reports analyzing RRT trends and practices worldwide. The present overview and analysis is based on our consolidated data from market survey as well as national database registries and databases of recent studies. Online HDF acceptance is growing fast in the two leading regions having approved the method, i.e. Europe and Asia Pacific, with a patient average growth rate of 12 to 24%, being far above the total patient HD growth rate of 6.6%. Today online HDF represents a new paradigm shift in RRT with promising clinical results. Further initiatives (e.g., Kidney Health Initiative, NICE) might provide further push for promoting HDF as a new standard of care in end stage kidney disease patients on a global scale.

Permissive fluid volume in adult patients undergoing extracorporeal membrane oxygenation treatment

Background

Extracorporeal membrane oxygenation (ECMO) is a cardiorespiratory support technique for patients with circulatory or pulmonary failure. Frequently, large-volume fluid resuscitation is needed to ensure sufficient extracorporeal blood flow in patients initiating ECMO. However, excessive overhydration is known to increase mortality in critically ill patients. Therefore, in order to define a tolerant volume range in patients undergoing ECMO treatment, the association between cumulative fluid balance (CFB) and outcome was evaluated in patients undergoing ECMO.

Methods

This retrospective multicenter cohort study was conducted with 723 patients who underwent ECMO in three tertiary care hospitals between 2005 and 2016. CFB was calculated as total fluid input minus total fluid output during the first 3 days from ECMO initiation. The patients were divided into groups that initiated ECMO owing to cardiovascular disease (CVD)-related or non-cardiovascular disease (non-CVD)-related causes. The primary endpoint was mortality within 90 days after ECMO commencement.

Results

Totals of 406 and 317 patients were included in the CVD and non-CVD groups, respectively. In the CVD group, the mean age was 58.4 ± 17.7 years, and 68.2% were male. The mean age was 55.7 ± 15.7 years, and 65.3% were male in the non-CVD group. The median CFB values were 64.7 and 53.5 ml/kg in the CVD and non-CVD groups, respectively. Multivariable analysis using Cox proportional hazards models revealed a significantly increased risk of 90-day mortality in patients with higher CFB values in both the CVD and non-CVD groups. However, the risks were elevated only in the two CFB quartile groups with the largest CFB amounts. Cubic spline models showed that mortality risk began to increase significantly when CFB was 82.3 ml/kg in the CVD group. In patients with respiratory diseases, the mortality risk increase was significant for those with CFB levels above 189.6 ml/kg.

Conclusions

Mortality risk did not increase until a certain level of fluid overload was reached in patients undergoing ECMO. Adequate fluid resuscitation is critical to improving outcomes in these patients.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2211-x) contains supplementary material, which is available to authorized users.

Differences in Amino Acid Loss Between High-Efficiency Hemodialysis and Postdilution and Predilution Hemodiafiltration Using High Convection Volume Exchange-A New Metabolic Scenario? A Pilot Study

OBJECTIVE

The objective of the study was to quantify the loss of total amino acids (TAAs), nonessential amino acids, essential amino acids, and branched chain amino acids (BCAAs) produced by high-efficiency hemodialysis (HEHD), postdilution hemodiafiltration (HDFpost), and predilution hemodiafiltration (HDFpre) using high ultrafiltration volumes; and to define the specific AA losses registered in HEHD, HDFpost, and HDFpre; to identify a potential metabolic and nutritional decline into protein energy wasting; to compare AA analysis of arterial blood samples taken from healthy controls and patients with end-stage renal disease undergoing hemodialysis.

DESIGN AND METHODS

Identical dialysis monitors, membranes, and dialysate/infusate were used to homogenize extracorporeal body influence. Ten patients were recruited and randomized to receive treatment with HEHD, HDFpost, and HDFpre it was used on-line dialytic water methodologies (OL); patients' AA arterial concentrations were measured at the start and on completion of dialysis; TAA from the dialyzer filter was calculated, and baseline levels were subsequently compared with findings obtained 1 year later. Finally, the results obtained were compared with the data from a study of 8 healthy volunteers conducted using bioimpedance analysis and laboratory blood tests to assess nutritional status.

RESULTS

A higher convective dose results in a higher weekly loss of TAA, nonessential AAs, essential AAs, and BCAAs (HEHD: 15.7 g; HDFpost-OL: 16.1 g; HDFpre-OL: 16.3 g, P < .01). After 12 months, the same hemodialys patients showed a reduced body and water intracellular mass and reduced phase angle. Arterial concentrations of TAAs and BCAAs were lower than those detected in healthy subjects (P < .01).

CONCLUSION

The study shows that the AA losses in dialytic liquid are greater after high exchange volume HDF techniques, especially HDFpre. The AA losses are not metabolically compensated, so these increase the derangements of predialytic arterial plasma AA levels. Both AA losses and arterial AA perturbations further worsened body composition already after 12 months of additional dialysis.

Prescribing Hemodialysis or Hemodiafiltration: When One Size Does Not Fit All the Proposal of a Personalized Approach Based on Comorbidity and Nutritional Status

There is no simple way to prescribe hemodialysis. Changes in the dialysis population, improvements in dialysis techniques, and different attitudes towards the initiation of dialysis have influenced treatment goals and, consequently, dialysis prescription. However, in clinical practice prescription of dialysis still often follows a "one size fits all" rule, and there is no agreed distinction between treatment goals for the younger, lower-risk population, and for older, high comorbidity patients. In the younger dialysis population, efficiency is our main goal, as assessed by the demonstrated close relationship between depuration (tested by kinetic adequacy) and survival. In the ageing dialysis population, tolerance is probably a better objective: "good dialysis" should allow the patient to attain a stable metabolic balance with minimal dialysis-related morbidity. We would like therefore to open the discussion on a personalized approach to dialysis prescription, focused on efficiency in younger patients and on tolerance in older ones, based on life expectancy, comorbidity, residual kidney function, and nutritional status, with particular attention placed on elderly, high-comorbidity populations, such as the ones presently treated in most European centers. Prescription of dialysis includes reaching decisions on the following elements: dialysis modality (hemodialysis (HD) or hemodiafiltration (HDF)); type of membrane (permeability, surface); and the frequency and duration of sessions. Blood and dialysate flow, anticoagulation, and reinfusion (in HDF) are also briefly discussed. The approach described in this concept paper was developed considering the following items: nutritional markers and integrated scores (albumin, pre-albumin, cholesterol; body size, Body Mass Index (BMI), Malnutrition Inflammation Score (MIS), and Subjective Global Assessment (SGA)); life expectancy (age, comorbidity (Charlson Index), and dialysis vintage); kinetic goals (Kt/V, normalized protein catabolic rate (n-PCR), calcium phosphate, parathyroid hormone (PTH), beta-2 microglobulin); technical aspects including vascular access (fistula versus catheter, degree of functionality); residual kidney function and weight gain; and dialysis tolerance (intradialytic hypotension, post-dialysis fatigue, and subjective evaluation of the effect of dialysis on quality of life). In the era of personalized medicine, we hope the approach described in this concept paper, which requires validation but has the merit of providing innovation, may be a first step towards raising attention on this issue and will be of help in guiding dialysis choices that exploit the extraordinary potential of the present dialysis "menu".

Current approaches to middle molecule removal: room for innovation

Aggressive removal of middle molecules or larger low-molecular-weight proteins (LMWPs) has been a growing concern following studies on their harmful effects on the mortality and morbidity of chronic dialysis patients. To remove larger LMWPs and some protein-bound uremic toxins (PBUTs), high- and medium-cutoff (HCOs and MCOs, respectively) membranes, convective therapy and protein adsorptive membranes are available. When we use HCO or MCO membranes for convective therapy, we have to take care to avoid massive albumin leakage during a dialysis session. Convection volume is an important element to increase middle molecule removal; however, a larger convection volume has a risk of larger leakage of albumin. Predilution hemodiafiltration is a useful measurement to increase larger LMWPs without massive albumin leakage. β2-microglobulin (B2M), α1-microglobulin (A1M) and albumin leakage during a dialysis session are useful parameters for assessing middle-molecule removal. Reduction ratios of B2M >80% and of A1M >35% are favorable to improve severe dialysis-related symptoms. The efficacy of middle molecule removal should be evaluated in comparison with clinical outcomes, mortality, morbidity and the improvement of dialysis-related symptoms. Recently some dialysis-related symptoms such as sleep disturbance, skin itchiness and dialysis hypotension have been recognized as good surrogate makers for mortality. Further studies to evaluate the relationship between middle molecule or PBUTs removal and the improvement of patient symptoms should be performed in well-designed randomized controlled trials.

Regulatory Considerations for Hemodiafiltration in the United States

Online hemodiafiltration provides greater removal of higher molecular weight uremic retention solutes than conventional high-flux hemodialysis. However, online hemodiafiltration is used sparsely in the United States in part because of a paucity of delivery systems cleared for clinical use by the US Food and Drug Administration. Although a pathway for regulatory approval exists in the United States, concerns remain, particularly regarding online production of the large volumes of sterile, nonpyrogenic substitution fluid infused directly into the bloodstream to maintain fluid balance. Clearly defined testing protocols, acceptable to Food and Drug Administration, will be useful to show that an online hemodiafiltration system is capable of routinely achieving a sterility assurance level of 10-6 and nonpyrogenic levels of endotoxin. Large-scale clinical experience has shown that systems providing this level of performance when combined with certain design features, such as redundancy, and an appropriate quality management process can routinely and safely produce substitution fluid for online hemodiafiltration.

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.

Overcoming glucose delivery by on-line hemodiafiltration: a feasible chimera for diabetics on dialysis

The increasing number of patients with diabetes undergoing renal replacement therapy has raised interest in the issue of glucose delivery with the substitution fluid-over 20 g per session. The ideal situation would be to have a glucose-containing bath to avoid glycemic disarrays and a glucose-free substitution fluid. But this seems a chimera because the substitution fluid is nothing else than an ultrapure dialysis bath. In this technical note, we present a cheap solution to realize the desired mix, using a commercially available glucose-free dialysate and adding glucose in the inlet dialysate compartment of the dialyzer by means of a common pump and a unique handmade T-tube. Our in vitro experiments showed glucose levels in the dialysate (mean ± SD, mg/dl): 99.7 ± 4.6 at baseline, 100.7 ± 7.3 at mid-session and 100.7 ± 2.1 at the end of dialysis, whereas measurements in the substitution fluid always gave a "low" output (p < 0.0001). Similar results were obtained in single 1- and 4-h in vivo experiments carried out in a non-diabetic overweight hemodialysis patient. Our simple, yet unequivocal, results lay the foundation for assembling a hemodialysis machine equipped with an infusion pump to modify the on-line substitution fluid without affecting the dialysate. This would overcome the ethical issue of delivering glucose intravenously in certain groups of patients.

Is High-Volume Online Hemodiafiltration Associated With Malnutrition?

Chronic malnutrition is a common problem in patients with end-stage renal disease on hemodialysis. Some studies have reported albumin loss into dialysis fluid during postdilution online hemodiafiltration (OL-HDF). The aim of the study was to assess the nutritional status of patients on high-volume OL-HDF and to demonstrate that higher convective clearances are not associated with malnutrition due to possible loss of nutrients with ultrafiltration. Demographic and clinical data, corporal composition with bioimpedance spectroscopy, dialysis features, albumin loss into dialysis fluid and laboratory parameters were collected in twenty-eight patients with ESRD undergoing postdilution OL-HDF with stable convective volumes over 28 L/session. Convective volume (CV) in the last six months was 32.51 ± 3.52 L per session. Cross-sectional analysis of dialysis features showed 32.7 ± 3.34 L of CV and high reduction rates of beta-2-microglobulin (84.2 ± 3.8%) and cystatin-C (81.6 ± 3.47%). Beta-2-microglobulin reduction showed a positive correlation with prealbumin levels (P = 0.048). CV was only correlated with cystatin-C reduction (P = 0.025). Estimated albumin loss into dialysis fluid (1.82 ± 1.05 g/session) was not related to laboratory or bioimpedance nutritional parameters, or to CV. Among patients with higher CV, serum albumin levels maintained more stability during the observational period. High volume OL-HDF results in better convective clearances and is not associated with malnutrition. Albumin and nutrients loss into dialysis fluid should not be a limiting factor of the substitution volume.

Successful Practice Transitioning Between Hemodialysis and Hemodiafiltration in Outpatient Units: Ten Key Issues for Physicians to Remember

Hemodiafiltration (HDF) during chronic renal replacement therapy (RRT) is a relatively new practice phenomenon, emerging over the last two decades. While the technological platforms utilized during chronic RRT are in many cases similar or effectively identical to conventional hemodialysis (HD), significant differences may emerge in daily practice. Several authors of this review moved practice site between the United States and the European Union and transitioned from an HD-based practice to predominantly HDF-practicing networks. In doing so, we became keenly aware of the potential pitfalls nephrologists may be facing during such transitions. This brief review is intended to provide a succinct overview of several practical concerns and complications nephrologists may encounter in daily practice of end-stage renal disease care, including but not limited to management of electrolytes, renal anemia and treatment goals and settings during HDF.

Mortality risk in patients on hemodiafiltration versus hemodialysis: a 'real-world' comparison from the DOPPS

Background

With its convective component, hemodiafiltration (HDF) provides better middle molecule clearance compared with hemodialysis (HD) and is postulated to improve survival. A previous analysis of Dialysis Outcomes and Practice Patterns Study (DOPPS) data in 1998-2001 found lower mortality rates for high replacement fluid volume HDF versus HD. Randomized controlled trials have not shown uniform survival advantage for HDF; in secondary (non-randomized) analyses, better outcomes were observed in patients receiving the highest convection volumes.

Methods

In a 'real-world' setting, we analyzed patients on dialysis >90 days from seven European countries in DOPPS Phases 4 and 5 (2009-15). Adjusted Cox regression was used to study HDF (versus HD) and mortality, overall and by replacement fluid volume.

Results

Among 8567 eligible patients, 2012 (23%) were on HDF, ranging from 42% in Sweden to 12% in Germany. Median follow-up was 1.5 years during which 1988 patients died. The adjusted mortality hazard ratio (95% confidence interval) was 1.14 (1.00-1.29) for any HDF versus HD and 1.08 (0.92-1.28) for HDF >20 L replacement fluid volume versus HD. Similar results were found for cardiovascular and infection-related mortality. In an additional analysis aiming to avoid treatment-by-indication bias, we did not observe lower mortality rates in facilities using more HDF (versus HD).

Conclusions

Our results do not support the notion that HDF provides superior patient survival. Further trials designed to test the effect of high-volume HDF (versus lower volume HDF versus HD) on clinical outcomes are needed to adequately inform clinical practices.

Ten-Year Survival of End-Stage Renal Disease Patients Treated with High-Efficiency Online Hemodiafiltration: A Cohort Study of a Center in South East Asia

BACKGROUND

Recently, in the first hemodiafiltration (HDF) experience report from South East Asia (SEA), we reported a 3-year prospective study demonstrating the various short-term benefits of high-efficiency online HDF (OL-HDF) over high-flux hemodialysis (HD). Very few long-term survival reports of high-efficiency OL-HDF are available and the data are heterogeneous and incomplete.

OBJECTIVES

The present historical cohort study was conducted to determine the long-term survival and outcome of high-efficiency OL-HDF-treated patients.

METHODS

Sixty-six high-efficiency OL-HDF treated patients at a center in SEA were included in the study. The prescription included blood and dialysis fluid flow rates of 400 and 800 mL/min, respectively. The post- or pre-dilution substitution fluid of 100 or 200 mL/min, respectively, was prescribed.

RESULTS

Of 66 HDF patients, whose age was 57.4 ± 14.0 years, there were 38 (58%) females. The majority of comorbidity was diabetes (36%). There were 33 (50%) incident HDF cases that were prescribed OL-HDF at the dialysis initiation and 33 (50%) prevalent HDF cases that were switched from HD to OL-HDF. The 1-, 3-, 5-, and 10-year survival rate were 95.1, 83.4, 77.7, and 61.8% respectively. The mean survival time was 8.99 ± 0.64 years. There were 15 transplantations and 15 deaths during this study periods. The 2 major causes of death were cardiovascular (33.3%) and infectious diseases (20%). Serum ferritin was the only parameter that correlated with mortality (HR 1.004, p = 0.005). There was comparable survival between incident and prevalent HDF cases. The survival after transplantation of a sub-group of patients who received kidney transplantation (KT) was not different from that of the overall HDF patients (p = 0.93).

CONCLUSIONS

High-efficiency OL-HDF could provide an excellent long-term survival nearly comparable to the KT sub-group.

Asymmetric cellulose triacetate is a safe and effective alternative for online haemodiafiltration

BACKGROUND

In post-dilution haemodiafiltration only synthetic membranes have been used to date. Asymmetric cellulose triacetate (ATA™) is now available, whose characteristics are suitable for this technique.

OBJECTIVES

To describe the in vivo performance and behaviour of this membrane, to identify its depurative effectiveness, use in clinical practice and its biocompatibility, both acute and after one month of treatment.

METHODS

Observational prospective study of 23 patients who were dialysed for 4 weeks using an ATA™ membrane and who maintained their prior regimen.

RESULTS

A total of 287 sessions were performed and 264 complete sessions were collected. With an effective time of 243.7 (17.6) min and a mean blood flow of 371.7 (23) ml/min, an average Kt of 56.3 (5.3) l was observed, as well as a convection volume of 27.1 (4.2) l, a filtration fraction of 29.9 (3.7) %, a urea reduction ratio (RR) of 81 (5.2) %, a creatinine RR of 74.7 (4.6) %, a β₂-microglobulin RR of 76.5 (4.8) % and a retinol binding protein RR of 18.6 (7.6) %. There were no technical problems or alarms. Changing the heparin dosage was not necessary. No increases in C3a or C5a concentrations or leukopenia were observed in the first 30min of the session. Neither the monocyte subpopulations nor IL-β1 or IL-6 were significantly altered after one month of treatment.

CONCLUSIONS

The new ATA™ membrane achieves adequate Kt and convection volume, without technical problems and with good biocompatibility and inflammatory profiles. It is therefore a valid option for post-dilution haemodiafiltration, particularly in patients allergic to synthetic membranes.

On-line hemodiafiltration did not induce an overproduction of oxidative stress and inflammatory cytokines in intensive care unit-acute kidney injury

Background

Though on-line intermittent hemodiafiltration (OL-IHDF) is a routine therapy for chronic dialysis patients, it is not yet widespread used in critically ill patients. This study was undergone to evaluate efficiency and tolerance of OL-IHDF and to appreciate inflammatory consequences of its use in intensive care unit (ICU)-acute kidney injury (AKI) patients.

Methods

In this prospective cohort study conducted in a medical academic ICU in France, 30 AKI patients who underwent OL-IHDF were included. OL-HDF used an ultrapure water production: AQ 1250 line with double reverse osmosis, a generator 5008 with a 1.8m² dialyzer with Polysulfone membrane (Fresenius Medical Care). Tolerance and efficiency of OL-IHDF were evaluated as well as its inflammatory risk by the measurement of plasma concentrations of proinflammatory (Interleukin 6, IL1β, IL8, Interferon γ) and anti-inflammatory (IL4, IL10) cytokines, Epidermal growth factor (EGF), Vascular Endothelial growth factor (VEGF) and Macrophage Chemoattractive Protein-1 (MCP-1) before and after sessions.

Results

Intradialytic hypotensive events were observed during 27/203 OL-IHDF sessions accounting for a mal-tolerated session’s rate at 13.3%. Mean delivered urea Kt/V per session was 1.12 ± 0.27 with a percentage of reduction for urea, creatinine, β2-microglobulin and cystatine C at 61.6 ± 8.8%, 55.3 ± 6.7%, 51.5 ± 8.7% and 44.5 ± 9.8% respectively. Production of superoxide anion by leukocytes, mean levels of pro- and anti-inflammatory cytokines and plasmatic concentrations of EGF, VEGF and MCP-1 did not differ before and after OL-IHDF sessions. We observed however a significant decrease of mean TNFα plasmatic concentrations from 8.2 ± 5.8 to 4.8 ± 3.5 pg/ml at the end of OL-IHDF.

Conclusions

OL-IHDF was not associated with an increase in pro and anti-inflammatory cytokines, oxidative stress or EGF, VEGF and MCP-1 in AKI patients and seems therefore a secure and feasible modality in ICUs.

Blue Planet dialysis: novel water-sparing strategies for reducing dialysate flow

INTRODUCTION

Hemodialysis (HD) is an expensive therapy in economic and in ecological terms, owing to a high carbon footprint and significant consumption of natural sources, especially water. Our aim was to review strategies to diminish waste of water in maintenance dialysis, exploring previously described water reuse trends and less known strategies for reducing the dialysate flow.

METHODS

We conducted a systematic review of water-sparing strategies, including the reuse of reverse osmosis rejected water and the reduction of dialysate flux. We performed a search in Medline, Pubmed, Scielo, OVID and Biblioteca Redentor, using key words: Dialysate flow rate, Dialysate flux, and decrease; excluding: online, peritoneal, continuous, blood access, needle, hemodiafiltration, acute, pharmacokinetics, increase. We limited our search to adult humans or in vitro trials in English, Spanish, Italian and Portuguese, between January 1980 and June 2017. We found 816 trials. 37 articles were retrieved for review, and 11 articles were analyzed.

RESULTS AND CONCLUSIONS

Conservation of water in chronic HD should be considered an important responsibility of healthcare practitioners all over the world. We present a wider usage of dialysate flow rates, considering that it would lead to significant water conservation without much compromise on dialysis efficacy in small patients. We believe that further investigation into the utility of reduced dialysate flux in different populations is needed to broaden our understanding of how we can use these techniques in order to significantly reduce water consumption during chronic HD while still ensuring optimum efficacy and efficiency of the therapy.

Hemodiafiltration Reduces All-Cause and Cardiovascular Mortality in Incident Hemodialysis Patients: A Propensity-Matched Cohort Study

BACKGROUND

The majority of studies suggesting that online hemodiafiltration reduces the risk of mortality compared to hemodialysis (HD) have been performed in dialysis-prevalent populations. In this report, we conducted an epidemiologic study of mortality in incident dialysis patients, comparing post-dilution online hemodiafiltration and high-flux HD, with propensity score matching (PSM) used to correct indication bias.

METHODS

Our study cohort comprised 3,075 incident dialysis patients treated in 64 Spanish Fresenius Medical Care clinics between January 2009 and December 2012. The primary outcome of this study was to investigate the impact of the type of renal replacement on all-cause mortality. An analysis of cardiovascular mortality was defined as the secondary outcome. To achieve these objectives, patients were followed until December 2016. Patients were categorized as high-flux HD patients if they underwent this treatment exclusively. If >90% of their treatment was with online hemodiafiltration, then the patient was grouped to that modality.

RESULTS

After PSM, a total of 1,012 patients were matched. Compared with patients on high-flux HD, those on online hemodiafiltration received a median replacement volume of 23.45 (interquartile range 21.27-25.51) L/session and manifested 24 and 33% reductions in all-cause and cardiovascular mortality (all-cause mortality hazards ratio [HR] 0.76, 95% CI 0.62-0.94 [p = 0.01]; and cardiovascular mortality HR 0.67, 95% CI 0.50-0.90 [p = 0.008]).

CONCLUSIONS

This study shows that post-dilution online hemodiafiltration reduces all-cause and cardiovascular mortality compared to high-flux HD in an incident HD population.