Dialysate saving by automated control of flow rates: comparison between individualized online hemodiafiltration and standard 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.

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.

Controversy on the CONVINCE study findings: the PRO take

The CONVINCE study, recently published in the New England Journal of Medicine, reveals a groundbreaking 23% reduction in the relative risk of all-cause mortality among end-stage kidney patients undergoing high convective volume hemodiafiltration. This significant finding challenges the conventional use of high-flux hemodialysis and offers hope for improving outcomes in chronic kidney disease patients. While some controversies surround the study's findings, including concerns about generalizability and the causes of death, it is essential to acknowledge the study's design and its main outcomes. The CONVINCE study, part of the HORIZON 2020 project, enrolled 1360 patients and demonstrated the superiority of hemodiafiltration in reducing all-cause mortality overall, as well as in specific patient subgroups (elderly, short vintage, non-diabetic, and those without cardiac issues). Interestingly, it was shown that hemodiafiltration had a protective effect against infection, including COVID-19. Future research will address sustainability, dose scaling effects, identification of subgroups especially likely to benefit and cost-effectiveness. However, for now, the findings strongly support a broader adoption of hemodiafiltration in renal replacement therapy, marking a significant advancement in the field.

Advanced hemodialysis equipment for more eco-friendly dialysis

Healthcare in general and dialysis care in particular are contributing to resource consumption and, thus, have a notable environmental footprint. Dialysis is a life-saving therapy but it entails the use of a broad range of consumables generating waste, and consumption of water and energy for the dialysis process. Various stakeholders in the healthcare sector are called upon to develop and to take measures to save resources and to make healthcare and dialysis more sustainable. Among these stakeholders are manufacturers of dialysis equipment and water purification systems. Dialysis equipment and consumables, together with care processes need to be advanced to reduce waste generation, enhance recyclability, optimize water purification efficiency and water use. Joint efforts should thus pave the way to enable delivering green dialysis and to contribute to environmentally sustainable health care.

Haemodialysis therapy and sustainable growth: a corporate experience in France

Introduction

Sustainable growth and environmental issues are currently a topic for all human activities, and dialysis represents a real challenge in this field because of high water and power consumption and the production of large amounts of care-related waste. In this article we describe data collection implemented in the NephroCare centres in France and the changes observed during a 13-year period regarding environmental parameters.

Methods

Monthly data collection (eco-reporting) was implemented in NephroCare centres in France in 2005. It covers three topics designed as key performance indicators (KPIs): electricity and water consumption and care-related waste production expressed, respectively, as kilowatt-hour (kWh), litres (L) and kilograms per session. We report on the three action plans (2005–10, 2011–14 and 2015–18) and changes observed during this 13-year period.

Results

During the period, power and water consumption declined by 29.6% (from 23.1 to 16.26 kWh/session) and 52% (from 801 to 382 L/session), respectively. At the same time, the yearly number of dialysis sessions has increased from 169 335 to 399 336. The sources of savings came both from improvements in the dialysis technology (dialysis machines and water treatment systems) and from updating and remodelling of the dialysis unit equipment and buildings. The care-related waste decreased from 1.8 to 1.1 kg because of regular staff training and the retrofiltration system, allowing the voiding of the remaining saline solution after dialysis. These savings have been estimated as equivalent to 102 440 tons of carbon dioxide.

Discussion

Implementation of KPIs and their regular monitoring by trained staff to evaluate water and power consumption and the reduction of care-related water production are essential to implement actions to reduce the impact of dialysis on the environment. These data show the importance of water treatment and dialysis technology to decrease water and power consumption and the production of care-related waste as well as upgrading or remodelling of buildings housing dialysis units. Other measures are discussed, including the reuse of rejected water by reverse osmosis, as well as behavioural changes that are needed to reach sustainable development of dialysis.

Conclusion

The first step to reach ‘green’ dialysis is to collect precise information from defined KPIs. This is the only way to design action plans to reduce the impact of dialysis therapy on the environment. Beyond this, the nephrology community must be sensitized to this challenge to be proactive and to anticipate future regulations.

Green nephrology and eco-dialysis: a position statement by the Italian Society of Nephrology

High-technology medicine saves lives and produces waste; this is the case of dialysis. The increasing amounts of waste products can be biologically dangerous in different ways: some represent a direct infectious or toxic danger for other living creatures (potentially contaminated or hazardous waste), while others are harmful for the planet (plastic and non-recycled waste). With the aim of increasing awareness, proposing joint actions and coordinating industrial and social interactions, the Italian Society of Nephrology is presenting this position statement on ways in which the environmental impact of caring for patients with kidney diseases can be reduced. Due to the particular relevance in waste management of dialysis, which produces up to 2 kg of potentially contaminated waste per session and about the same weight of potentially recyclable materials, together with technological waste (dialysis machines), and involves high water and electricity consumption, the position statement mainly focuses on dialysis management, identifying ten first affordable actions: (1) reducing the burden of dialysis (whenever possible adopting an intent to delay strategy, with wide use of incremental schedules); (2) limiting drugs and favouring "natural" medicine focussing on lifestyle and diet; (3) encouraging the reuse of "household" hospital material; (4) recycling paper and glass; (5) recycling non-contaminated plastic; (6) reducing water consumption; (7) reducing energy consumption; (8) introducing environmental-impact criteria in checklists for evaluating dialysis machines and supplies; (9) encouraging well-planned triage of contaminated and non-contaminated materials; (10) demanding planet-friendly approaches in the building of new facilities.

What is the optimum dialysate flow in post-dilution online haemodiafiltration?

INTRODUCTION

In post-dilution online hemodiafiltration (OL-HDF), the only recommendation concerning the dialysate, or dialysis fluid, refers to its purity. No study has yet determined whether using a high dialysate flow (Qd) is useful for increasing Kt or ultrafiltration-infusion volume.

OBJECTIVE

Study the influence of Qd on Kt and on infusion volume in OL-HDF.

MATERIAL AND METHODS

This was a prospective crossover study. There were 37 patients to whom 6 sessions of OL-HDF were administered at 3 different Qds: 500, 600 and 700ml/min. A 5008(®) monitor was used for the dialysis in 21 patients, while an AK-200(®) was used in 17. The dialysers used were: 20 with FX 800(®) and 17 with Polyflux-210(®). The rest of the parameters were kept constant. Monitor data collected were effective blood flow, effective dialysis time, final Kt and infused volume.

RESULTS

We found that using a Qd of 600 or 700ml/min increased Kt by 1.7% compared to using a Qd of 500ml/min. Differences in infusion volume were not significant. Increasing Qd from 500ml/min to 600 and 700ml/min increased dialysate consumption by 20% and 40%, respectively.

CONCLUSIONS

With the monitors and dialysers currently used in OL-HDF, a Qd higher than 500ml/min is unhelpful for increasing the efficacy of Kt or infusion volume. Consequently, using a high Qd wastes water, a truly important resource both from the ecological and economic points of view.

Haemodiafiltration, haemofiltration and haemodialysis for end-stage kidney disease

BACKGROUND

Convective dialysis modalities (haemofiltration (HF), haemodiafiltration (HDF), and acetate-free biofiltration (AFB)) removed excess body fluid across the dialysis membrane with positive pressure and accumulated middle- and larger-size accumulated solutes more efficiently than haemodialysis (HD). This increased larger solute removal combined with use of ultra-pure dialysis fluid in convective dialysis is hypothesised to reduce the frequency and severity of symptoms during dialysis as well as improve clinical outcomes. Convective dialysis therapies (HDF and HF) are associated with lower mortality compared to diffusive therapy (HD) in observational studies. This is an update of a review first published in 2006.

OBJECTIVES

To compare convective (HF, HDF, or AFB) with diffusive (HD) dialysis modalities on clinical outcomes (mortality, major cardiovascular events, hospitalisation and treatment-related adverse events) in men and women with end-stage kidney disease (ESKD).

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register (to 18 February 2015) through contact with a Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

We included randomised controlled trials comparing convective therapy (HF, HDF, AFB) with another convective therapy or diffusive therapy (HD) for treatment of ESKD.

DATA COLLECTION AND ANALYSIS

Two independent authors identified studies, extracted data and assessed study risk of bias. We summarised treatment effects using the random effects model. We reported results as a risk ratio (RR) for dichotomous outcomes and mean difference (MD) for continuous data together with 95% confidence intervals (CI). We assessed for heterogeneity using the Chi(2) test and explored the amount of variation in treatment estimates beyond that expected by chance using the I(2) statistic.

MAIN RESULTS

Twenty studies comprising 667 participants were included in the 2006 review. In that review, there was insufficient evidence of treatment effects on major clinical outcomes to draw clinically meaningful conclusions. Searching to February 2015 identified 40 eligible studies comprising 3483 participants overall. In total, 35 studies (4039 participants) compared HF, HDF or AFB with HD, three studies (54 participants) compared AFB with HDF, and three studies (129 participants) compared HDF with HF.Risks of bias in all studies were generally high resulting in low confidence in estimated treatment effects. Convective dialysis had no significant effect on all-cause mortality (11 studies, 3396 participants: RR 0.87, 95% CI 0.72 to 1.05; I(2) = 34%), but significantly reduced cardiovascular mortality (6 studies, 2889 participants: RR 0.75, 95% CI 0.61 to 0.92; I(2) = 0%). One study reported no significant effect on rates of nonfatal cardiovascular events (714 participants: RR 1.14, 95% CI 0.86 to 1.50) and two studies showed no significant difference in hospitalisation (2 studies, 1688 participants: RR 1.23, 95% CI 0.93 to 1.63; I(2) = 0%). One study reported rates of hypotension during dialysis were significantly reduced with convective therapy (906 participants: RR 0.72, 95% CI 0.66 to 0.80). Adverse events were not systematically evaluated in most studies and data for health-related quality of life were sparse. Convective therapies significantly reduced predialysis levels of B2 microglobulin (12 studies, 1813 participants: MD -5.55 mg/dL, 95% CI -9.11 to -1.98; I(2) = 94%) and increased dialysis dose (Kt/V urea) (14 studies, 2022 participants: MD 0.07, 95% CI -0.00 to 0.14; I(2) = 90%) compared to diffusive therapy, but results across studies were very heterogeneous. Sensitivity analyses limited to studies comparing HDF with HD showed very similar results. Directly comparative data for differing types of convective dialysis were insufficient to draw conclusions.Studies had important risks of bias leading to low confidence in the summary estimates and were generally limited to patients who had adequate dialysis vascular access.

AUTHORS' CONCLUSIONS

Convective dialysis may reduce cardiovascular but not all-cause mortality and effects on nonfatal cardiovascular events and hospitalisation are inconclusive. However, any treatment benefits of convective dialysis on all patient outcomes including cardiovascular death are unreliable due to limitations in study methods and reporting. Future studies which assess treatment effects of convection dose on patient outcomes including mortality and cardiovascular events would be informative.