Mortality and Hospitalizations in Intensive Dialysis: A Systematic Review and Meta-Analysis

Longitudinal impact of extended-hours hemodialysis with a liberalized diet on nutritional status and survival outcomes: findings from the LIBERTY cohort

BACKGROUND

Protein-energy wasting (PEW), a unique weight loss linked to nutritional and metabolic abnormalities, is common in patients undergoing hemodialysis (HD) and associated with adverse outcomes. This study investigated whether extended-hours HD combined with a liberalized diet could overcome PEW and improve survival.

METHODS

The body mass index (BMI) and survival outcomes in patients undergoing extended-hours HD were evaluated for up to 8 years using data from the LIBeralized diet Extended-houRs hemodialysis Therapy (LIBERTY) cohort. Extended-hours HD was defined as weekly dialysis length ≥ 18 h.

RESULTS

The LIBERTY cohort included 402 patients who initiated extended-hours HD. An increase in the length and frequency of HD sessions was observed over time, with approximately 70% and 20% of patients undergoing extended-hours HD for > 21 h/week and > 3 sessions/week at 5 years, respectively. The BMI and percentage creatinine generation rate were maintained over time, with no substantial increase in the phosphorus and potassium levels. The estimated BMI initially increased, and thereafter plateaued over time in patients with a baseline BMI < 25 kg/m2, whereas it decreased gradually in patients with a baseline BMI ≥ 25 kg/m2 after several years from baseline. Ninety-one patients died, and 108 discontinued extended-hours HD during the median follow-up period of 6.2 years (interquartile range, 3.5-8.0), yielding a 5-year survival rate of 85%.

CONCLUSIONS

Extended-hours HD with a liberalized diet may help achieve favorable survival outcomes and maintain nutritional status. Thus, it is a promising treatment option for managing PEW in patients undergoing HD.

I Brazilian guideline on hypertension in dialysis of the Brazilian Society of Nephrology

Hypertension in dialysis patients (HTND) has a high prevalence, affecting at least 80% or more of patients, and its management in the nephrology practice is heterogeneous and often empirical. Knowing how to define, understand the pathophysiology, diagnose, monitor and treat with lifestyle changes, and adjust antihypertensive drugs to achieve the recommended blood pressure (BP) target - to reduce morbidity and mortality - requires specific knowl-edge and approaches within the contexts of hemodialysis (HD) and peritoneal dialysis (PD). This document is the first guideline of the Brazilian Society of Nephrology, developed by the departments of Hypertension and Dialysis. It aims to guide physicians who provide care in dialysis centers on how to manage patients with HTND, in a comprehensive and individualized manner, based on the critical appraisal of the best available scientific evidence. When such evidence is scarce or unavailable, the opinion of specialists should be recommended. The different topics covered include HTND definition (pre-HD BP ≥ 140/90 mmHg and post-HD BP ≥ 130/80 mmHg), epidemiology, and pathophysiology; diagnosis of HTND preferably with BP measurements outside the dialysis setting (BP ≥ 130/80 mmHg); complementary assessment; blood pressure targets; non-pharmacological treatment; use of the most appropriate antihypertensive medications; special situations; and complications of HTND, predominantly cardiovascular ones.

Dialysis for Chronic Kidney Failure: A Review

Importance

More than 3.5 million people worldwide and 540 000 individuals in the US receive maintenance hemodialysis or peritoneal dialysis for the treatment of chronic kidney failure. The 5-year survival rate is approximately 40% after initiation of maintenance dialysis.

Observations

Hemodialysis and peritoneal dialysis remove metabolic waste and excess body water and rebalance electrolytes to sustain life. There is no recommended estimated glomerular filtration rate (eGFR) threshold for initiating dialysis, and patient-clinician shared decision-making should help determine when to initiate dialysis. Persistent signs and symptoms of uremia (eg, nausea, fatigue) and volume overload (eg, dyspnea, peripheral edema), worsening eGFR, metabolic acidosis, and hyperkalemia inform the timing of therapy initiation. A randomized clinical trial reported no mortality benefit to starting dialysis at higher eGFR (10-14 mL/min/1.73 m2) vs lower eGFR (5-7 mL/min/1.73 m2) levels. Observational data suggested no differences in 5-year mortality with use of hemodialysis vs peritoneal dialysis. Cardiovascular (eg, arrhythmias, cardiac arrest) and infection-related complications of maintenance dialysis are common. In the US, hemodialysis catheter-related bloodstream infections occur at a rate of 1.1 to 5.5 episodes per 1000 catheter-days and affect approximately 50% of patients within 6 months of catheter placement. Peritonitis occurs at a rate of 0.26 episodes per patient-year and affects about 30% of individuals in the first year of peritoneal dialysis therapy. Chronic kidney failure-related systemic complications, such as anemia, hyperphosphatemia, hypocalcemia, and hypertension, often require pharmacologic treatment. Hypotension during dialysis, refractory symptoms (eg, muscle cramps, itching), and malfunction of dialysis access can interfere with delivery of dialysis.

Conclusions and Relevance

In 2021, more than 540 000 patients in the US received maintenance hemodialysis or peritoneal dialysis for treatment of chronic kidney failure. Five-year survival rate after initiation of maintenance dialysis is approximately 40%, and the mortality rate is similar with hemodialysis and peritoneal dialysis. Decisions about dialysis initiation timing and modality are influenced by patient symptoms, laboratory trajectories, patient preferences, and therapy cost and availability and should include shared decision-making.

Advances in Human-Centered Care to Address Contemporary Unmet Needs in Chronic Dialysis

Advances in the treatment of kidney failure with chronic dialysis have stagnated over the past three decades, with over 50% of patients still managed by conventional in-hospital haemodialysis. In parallel, the demands of chronic dialysis medical care have changed and evolved due to a growing population that has higher frailty and multimorbidity. Thus, the gap between the needs of kidney failure patients and the healthcare capability to provide effective overall management has widened. To address this problem, healthcare policy has increasingly aligned towards a human-centred approach. The paradigm shift of human-centred approach places patients at the forefront of decision-making processes, ensuring that specific needs are understood and prioritised. Integration of human-centred approaches with patient care has been shown to improve satisfaction and quality of life. The aim of this narrative is to evaluate the current clinical challenges for managing kidney failure for dialysis providers; summarise current experiences and unmet needs of chronic dialysis patients; and finally emphasise how human-centred care has advanced chronic dialysis care. Specific incremental advances include implementation of renal supportive care; home-assisted dialysis; hybrid dialysis; refinements to dialysis methods; whereas emerging advances include portable and wearable dialysis devices and the potential for the integration of artificial intelligence in clinical practice.

Actioning the findings of hard endpoint clinical trials as they emerge in the realm of chronic kidney disease care: a review and a call to action

Fewer than half of patients treated with hemodialysis survive 5 years. Multiple therapeutics are used to address the complications of advanced chronic kidney disease but most have not been found to improve clinical outcomes. Clinical trials of treatment innovations for chronic kidney diseases and dialysis care have been suboptimal in number and quality. Recent trials are changing this trend. Practice and policy change when new evidence emerges remains frequently impeded by resource and organizational constraints and accordingly, clinical practice guidelines are updated years or decades after definitive evidence is produced. Ultimately, practice change in health systems is slow, leading to impaired uptake of effective medical interventions and lower value healthcare, although innovations in rapid guideline production are emerging. What can be done to ensure that conclusive evidence is taken up in practice, policy and healthcare funding? We use the example of the recently published hard endpoint study "Comparison of high-dose HDF with high-flux HD" (CONVINCE) (hemodiafiltration versus hemodialysis), to explain how a new trial can impact on medical knowledge and change in practices. We (i) assess how the trial can be placed in the context of the totality of the evidence, (ii) define whether or not further trials of convective dialysis therapies are still needed and (iii) examine whether the evidence for convective therapies is now ready to inform practice, policy and funding change. When looking at CONVINCE in the context of the totality of evidence, we show that it addresses dialysis quality improvement priorities and is consistent with other trials evaluating convective dialysis therapies, and that the evidence for convective dialysis therapies is now definitive. Once updated evidence for cost-effectiveness in specific healthcare settings and patient-reported outcomes become available, we should therefore determine whether or not clinical practice guidelines should recommend uptake of convective dialysis therapies routinely, and move on to evaluating other treatments.

Patient Survival With Extended Home Hemodialysis Compared to In-Center Conventional Hemodialysis

Introduction

More frequent and/or longer hemodialysis (HD) has been associated with improvements in numerous clinical outcomes in patients on dialysis. Home HD (HHD), which allows more frequent and/or longer dialysis with lower cost and flexibility in treatment planning, is not widely used worldwide. Although, retrospective studies have indicated better survival with HHD, this issue remains controversial. In this multicenter study, we compared thrice-weekly extended HHD with in-center conventional HD (ICHD) in a large patient population with a long-term follow-up.

Methods

We matched 349 patients starting HHD between 2010 and 2014 with 1047 concurrent patients on ICHD by using propensity scores. Patients were followed-up with from their respective baseline until September 30, 2018. The primary outcome was overall survival. Secondary outcomes were technique survival; hospitalization; and changes in clinical, laboratory, and medication parameters.

Results

The mean duration of dialysis session was 418 ± 54 minutes in HHD and 242 ± 10 minutes in patients on ICHD. All-cause mortality rate was 3.76 and 6.27 per 100 patient-years in the HHD and the ICHD groups, respectively. In the intention-to-treat analysis, HHD was associated with a 40% lower risk for all-cause mortality than ICHD (hazard ratio [HR] = 0.60; 95% confidence interval [CI] 0.45 to 0.80; P < 0.001). In HHD, the 5-year technical survival was 86.5%. HHD treatment provided better phosphate and blood pressure (BP) control, improvements in nutrition and inflammation, and reduction in hospitalization days and medication requirement.

Conclusion

These results indicate that extended HHD is associated with higher survival and better outcomes compared to ICHD.

Portable, wearable and implantable artificial kidney systems: needs, opportunities and challenges

Haemodialysis is life sustaining but expensive, provides limited removal of uraemic solutes, is associated with poor patient quality of life and has a large carbon footprint. Innovative dialysis technologies such as portable, wearable and implantable artificial kidney systems are being developed with the aim of addressing these issues and improving patient care. An important challenge for these technologies is the need for continuous regeneration of a small volume of dialysate. Dialysate recycling systems based on sorbents have great potential for such regeneration. Novel dialysis membranes composed of polymeric or inorganic materials are being developed to improve the removal of a broad range of uraemic toxins, with low levels of membrane fouling compared with currently available synthetic membranes. To achieve more complete therapy and provide important biological functions, these novel membranes could be combined with bioartificial kidneys, which consist of artificial membranes combined with kidney cells. Implementation of these systems will require robust cell sourcing; cell culture facilities annexed to dialysis centres; large-scale, low-cost production; and quality control measures. These challenges are not trivial, and global initiatives involving all relevant stakeholders, including academics, industrialists, medical professionals and patients with kidney disease, are required to achieve important technological breakthroughs.

All-Cause Standardized Mortality Ratio in Hemodialysis and Peritoneal Dialysis Patients: A Nationwide Population-Based Cohort Study

Patients with end-stage renal disease (ESRD) are at a higher mortality risk compared with the general population. Previous studies have described a relationship between mortality and patients with ESRD, but the data on standardized mortality ratio (SMR) corresponding to different causes of death in patients undergoing hemodialysis (HD) and peritoneal dialysis (PD) are limited. This study was designed as a nationwide population-based retrospective cohort study. Incident dialysis patients between January 2000 and December 2015 in Taiwan were included. Using data acquired from the Taiwan Death Registry, SMR values were calculated and compared with the overall survival. The results showed there were a total of 128,966 patients enrolled, including 117,376 incident HD patients and 11,590 incident PD patients. It was found that 75,297 patients (58.4%) died during the period of 2000-2017. The overall SMR was 5.21. The neoplasms SMR was 2.11; the endocrine, nutritional, metabolic, and immunity disorders SMR was 13.53; the circulatory system SMR was 4.31; the respiratory system SMR was 2.59; the digestive system SMR was 6.1; and the genitourinary system SMR was 27.22. Therefore, more attention should be paid to these diseases in clinical care.

Hypertension and cardiomyopathy associated with chronic kidney disease: epidemiology, pathogenesis and treatment considerations

Chronic kidney disease (CKD) is a complex condition with a prevalence of 10-15% worldwide. An inverse-graded relationship exists between cardiovascular events and mortality with kidney function which is independent of age, sex, and other risk factors. The proportion of deaths due to heart failure and sudden cardiac death increase with progression of chronic kidney disease with relatively fewer deaths from atheromatous, vasculo-occlusive processes. This phenomenon can largely be explained by the increased prevalence of CKD-associated cardiomyopathy with worsening kidney function. The key features of CKD-associated cardiomyopathy are increased left ventricular mass and left ventricular hypertrophy, diastolic and systolic left ventricular dysfunction, and profound cardiac fibrosis on histology. While these features have predominantly been described in patients with advanced kidney disease on dialysis treatment, patients with only mild to moderate renal impairment already exhibit structural and functional changes consistent with CKD-associated cardiomyopathy. In this review we discuss the key drivers of CKD-associated cardiomyopathy and the key role of hypertension in its pathogenesis. We also evaluate existing, as well as developing therapies in the treatment of CKD-associated cardiomyopathy.

Epidemiology of haemodialysis outcomes

Haemodialysis (HD) is the commonest form of kidney replacement therapy in the world, accounting for approximately 69% of all kidney replacement therapy and 89% of all dialysis. Over the last six decades since the inception of HD, dialysis technology and patient access to the therapy have advanced considerably, particularly in high-income countries. However, HD availability, accessibility, cost and outcomes vary widely across the world and, overall, the rates of impaired quality of life, morbidity and mortality are high. Cardiovascular disease affects more than two-thirds of people receiving HD, is the major cause of morbidity and accounts for almost 50% of mortality. In addition, patients on HD have high symptom loads and are often under considerable financial strain. Despite the many advances in HD technology and delivery systems that have been achieved since the treatment was first developed, poor outcomes among patients receiving HD remain a major public health concern. Understanding the epidemiology of HD outcomes, why they might vary across different populations and how they might be improved is therefore crucial, although this goal is hampered by the considerable heterogeneity in the monitoring and reporting of these outcomes across settings.

This Review examines the epidemiology of haemodialysis outcomes — clinical, patient-reported and surrogate outcomes — across world regions and populations, including vulnerable individuals. The authors also discuss the current status of monitoring and reporting of haemodialysis outcomes and potential strategies for improvement.

Nearly 4 million people in the world are living on kidney replacement therapy (KRT), and haemodialysis (HD) remains the commonest form of KRT, accounting for approximately 69% of all KRT and 89% of all dialysis.

Dialysis technology and patient access to KRT have advanced substantially since the 1960s, particularly in high-income countries. However, HD availability, accessibility, cost and outcomes continue to vary widely across countries, particularly among disadvantaged populations (including Indigenous peoples, women and people at the extremes of age).

Cardiovascular disease affects over two-thirds of people receiving HD, is the major cause of morbidity and accounts for almost 50% of mortality; mortality among patients on HD is significantly higher than that of their counterparts in the general population, and treated kidney failure has a higher mortality than many types of cancer. Patients on HD also experience high burdens of symptoms, poor quality of life and financial difficulties.

Careful monitoring of the outcomes of patients on HD is essential to develop effective strategies for risk reduction. Outcome measures are highly variable across regions, countries, centres and segments of the population. Establishing kidney registries that collect a variety of clinical and patient-reported outcomes using harmonized definitions is therefore crucial.

Evaluation of HD outcomes should include the impact on family and friends, and personal finances, and should examine inequities in disadvantaged populations, who comprise a large proportion of the HD population.

Artificial Kidney Engineering: The Development of Dialysis Membranes for Blood Purification

The artificial kidney, one of the greatest medical inventions in the 20th century, has saved innumerable lives with end stage renal disease. Designs of artificial kidney evolved dramatically in decades of development. A hollow-fibered membrane with well controlled blood and dialysate flow became the major design of the modern artificial kidney. Although they have been well established to prolong patients’ lives, the modern blood purification system is still imperfect. Patient’s quality of life, complications, and lack of metabolic functions are shortcomings of current blood purification treatment. The direction of future artificial kidneys is toward miniaturization, better biocompatibility, and providing metabolic functions. Studies and trials of silicon nanopore membranes, tissue engineering for renal cell bioreactors, and dialysate regeneration are all under development to overcome the shortcomings of current artificial kidneys. With all these advancements, wearable or implantable artificial kidneys will be achievable.

Home versus In-Center Dialysis and Day of the Week Hospitalization: A Cohort Study

Background

The dialysis treatment day after the 2-day interdialytic interval (Monday/Tuesday) is associated with a heightened risk of hospitalization for patients on in-center hemodialysis (ICHD). In this national cohort study, we sought to characterize hospitalizations by day of the week for patients receiving ICHD, home HD (HHD), and peritoneal dialysis (PD) and to identify whether there were differences in the probability of a Monday/Tuesday admission for each modality type.

Methods

Patients on maintenance dialysis in Canada were analyzed from 2005 to 2014 using the Canadian Organ Replacement Register. Patients on hemodialysis were categorized as those receiving ICHD, HHD, frequent ICHD, or frequent HHD (the latter two included short daily and nocturnal HD). Hospitalizations were attributed to the previous treatment if they occurred within 30 days of a treatment change. Differences in the proportion of patients experiencing a Monday/Tuesday admission with all other days of the week were compared using a generalized linear model with binomial distribution and reported using adjusted odds ratios (OR) with 95% CIs.

Results

Overall, 27,430 individuals experienced 111,748 hospitalization episodes. Rates per 1000 patient days were 3.76, 2.98, 2.71, 2.16, and 2.13 for each of frequent ICHD, ICHD, PD, HHD, and frequent HHD, respectively. Compared with those on ICHD, only patients receiving frequent HHD (OR, 0.89; 95% CI, 0.81 to 0.97) and PD (OR, 0.95; 95% CI, 0.93 to 0.97) had a lower odds of experiencing a Monday/Tuesday admission. The OR was lower when restricted to hospitalization episodes for cardiovascular reasons comparing frequent HHD with ICHD (OR, 0.68; 95% CI, 0.48 to 0.96).

Conclusion

In this nationally representative cohort, we identified that the probability of a Monday/Tuesday admission was lower for frequent HHD and PD compared with ICHD, most notably for hospitalizations due to cardiovascular causes. Gaining a better understanding of the reasons behind this observation may help to develop future strategies to reduce overall and cause-specific hospitalization for patients receiving dialysis.

Survival comparisons in home hemodialysis: Understanding the present and looking to the future

A number of studies have compared relative survival for home hemodialysis patients (including longer hours/more frequent schedules) and other forms of renal replacement therapy. While informative, many of these studies have been limited by issues pertaining to their observational design including selection bias and residual confounding. Furthermore the few randomized controlled trials that have been conducted have been underpowered to detect a survival difference. Finally, in the face of a growing recognition of the value of patient-important outcomes beyond survival, the focus of comparisons between dialysis modalities may be changing. In this review, we will discuss the determinants of survival for patients receiving home hemodialysis and address the various studies that have compared relative survival for differing home hemodialysis schedules to each of in-center hemodialysis, peritoneal dialysis and transplantation. We will conclude this review by discussing whether there is an ongoing role for survival analyses in home hemodialysis.

Nocturnal Hemodialysis: Why Aren't More People Doing It?

Nocturnal hemodialysis is a form of intensive hemodialysis, which may be done in center or at home. Despite the documented clinical and economic benefits of ncturnal hemodialysis, uptake of this modality has been relatively low. In this review, we aim to address the potential barriers and possible mitigation strategies. Among the patient-related barriers, lack of knowledge and awareness remains the most common barrier, while administrative inertia to change from conventional in-center hemodialysis continues to be a challenge. Current global effort to grow home dialysis will re-focus the need for better patient education, innovate home dialysis technology, and evolve new models of care. New patient-focused policy will allow changes in reimbursement and develop appropriate momentum toward an integrated "home first model" to kidney replacement therapy.

Quality Assurance and Preventing Serious Adverse Events in the Home Hemodialysis Setting

Patient safety is of the utmost importance in home hemodialysis (HHD). Recognizing that there are risks related to vascular access (both infectious and noninfectious events), dialysis water quality, and procedural-related adverse events (including arteriovenous fistula needle dislodgement or air embolism), there is a need for systematic identification and management. Although adverse events are relatively infrequent in HHD, the potential consequences of these events may include significant morbidity, HHD treatment failure, or death. Therefore, having a systematic framework to review each event, audit and retrain patient technique, disclose and discuss events with patients, home unit staff and device companies (if relevant) and determine preventative measures to avoid future adverse events, is crucial. In this review, we will describe the literature around the types and relative frequency of serious adverse events in the HHD setting and we will outline a quality assurance framework for capturing, managing, and avoiding serious adverse events. Finally, we will describe some of the novel existing approaches to preventing or addressing serious adverse events and critical knowledge gaps that should be evaluated in future study.

Flow balance optimization and fluid removal accuracy with the Quanta SC+ hemodialysis system

BACKGROUND

Fluid management is integral to hemodialysis, both to correct abnormalities in a patient's plasma composition and to maintain fluid balance. Consequently, accurate net fluid removal during treatment is a critical design element of hemodialysis machines. As dialyzers have evolved, with increased ranges of ultrafiltration coefficients available, it has become more challenging for dialysis machines to minimize errors in flow balance and net fluid removal.

RESEARCH DESIGN AND METHODS

This paper describes the design, evaluation and experimental performance of the flow balance and ultrafiltration module of the SC+ system to deliver clinically specified fluid removal with both passive and active control measures, in laboratory conditions designed to simulate a wide range of therapies.

RESULTS

The use of passive and active control allows the errors to be minimized across a wider dynamic range of conditions. For the SC+ system, the average flow balance error was 1 mL/hr with an SD of 19 mL/hr and with ultrafiltration it was 13 mL/hr and an SD of 20 ml/hr across all conditions.

CONCLUSIONS

This paper demonstrates that the SC+ hemodialysis system, a small, simple and versatile CE marked device, operates within the limits required by international standards across a wide range of experimental conditions.

No evidence of a legacy effect on survival following randomization to extended hours dialysis in the ACTIVE Dialysis trial

AIM

Extended hours haemodialysis is associated with superior survival to standard hours. However, residual confounding limits the interpretation of this observation. We aimed to determine the effect of a period of extended hours dialysis on long-term survival among participants in the ACTIVE Dialysis trial.

METHODS

Two-hundred maintenance haemodialysis recipients were randomized to extended hours dialysis (median 24 h/wk) or standard hours dialysis (median 12 h/wk) for 12 months. Further pre-specified observational follow up occurred at 24, 36 and 60 months. Vital status and modality of renal replacement therapy were ascertained.

RESULTS

Over the 5 years, 38 participants died, 30 received a renal transplant, and 6 were lost to follow up. Total weekly dialysis hours did not differ between standard and extended groups during the follow-up period (14.1 hours [95%CI 13.4-14.8] vs 14.8 hours [95%CI 14.1-15.6]; P = .16). There was no difference in all-cause mortality (hazard ratio for extended hours 0.91 [95%CI 0.48-1.72]; P = .77). Similar results were obtained after censoring participants at transplantation, and after adjusting for potential confounding variables. Subgroup analysis did not reveal differences in treatment effect by region, dialysis setting or vintage (P-interaction .51, .54, .12, respectively).

CONCLUSION

Twelve months of extended hours dialysis did not improve long-term survival nor affect dialysis hours after the intervention period. An urgent need remains to further define the optimal dialysis intensity across the broad range of dialysis recipients.

Enhancement of solute clearance using pulsatile push-pull dialysate flow for the Quanta SC+: A novel clinic-to-home haemodialysis system

BACKGROUND AND OBJECTIVE

The SC+ haemodialysis system developed by Quanta Dialysis Technologies is a small, easy-to-use dialysis system designed to improve patient access to self-care and home haemodialysis. A prototype variant of the standard SC+ device with a modified fluidic management system generating a pulsatile push-pull dialysate flow through the dialyser during use has been developed for evaluation. It was hypothesized that, as a consequence of the pulsatile push-pull flow through the dialyser, the boundary layers at the membrane surface would be disrupted, thereby enhancing solute transport across the membrane, modifying protein fouling and maintaining the surface area available for mass and fluid transport throughout the whole treatment, leading to solute transport (clearance) enhancement compared to normal haemodialysis (HD) operation.

METHODS

The pumping action of the SC+ system was modified by altering the sequence and timings of the valves and pumps associated with the flow balancing chambers that push and pull dialysis fluid to and from the dialyser. Using this unique prototype device, solute clearance performance was assessed across a range of molecular weights in two related series of laboratory bench studies. The first measured dialysis fluid moving across the dialyser membrane using ultrasonic flowmeters to establish the validity of the approach; solute clearance was subsequently measured using fluorescently tagged dextran molecules as surrogates for uraemic toxins. The second study used human blood doped with uraemic toxins collected from the spent dialysate of dialysis patients to quantify solute transport. In both, the performance of the SC+ prototype was assessed alongside reference devices operating in HD and pre-dilution haemodiafiltration (HDF) modes.

RESULTS

Initial testing with fluorescein-tagged dextran molecules (0.3 kDa, 4 kDa, 10 kDa and 20 kDa) established the validity of the experimental pulsatile push-pull operation in the SC+ system to enhance clearance and demonstrated a 10 to 15% improvement above the current HD mode used in clinic today. The magnitude of the observed enhancement compared favourably with that achieved using pre-dilution HDF with a substitution fluid flow rate of 60 mL/min (equivalent to a substitution volume of 14.4 L in a 4-hour session) with the same dialyser and marker molecules. Additional testing using human blood indicated a comparable performance to pre-dilution HDF; however, in contrast with HDF, which demonstrated a gradual decrease in solute removal, the clearance values using the pulsatile push-pull method on the SC+ system were maintained over the entire duration of treatment. Overall albumin losses were not different.

CONCLUSIONS

Results obtained using an experimental pulsatile push-pull dialysis flow configuration with an aqueous blood analogue and human blood ex vivo demonstrate an enhancement of solute transport across the dialyser membrane. The level of enhancement makes this approach comparable with that achieved using pre-dilution HDF with a substitution fluid flow rate of 60 mL/min (equivalent to a substitution volume of 14.4 L in a 4-hour session). The observed enhancement of solute transport is attributed to the disruption of the boundary layers at the fluid-membrane interface which, when used with blood, minimizes protein fouling and maintains the surface area.

Urea removal strategies for dialysate regeneration in a wearable artificial kidney

The availability of a wearable artificial kidney (WAK) that provides dialysis outside the hospital would be an important advancement for dialysis patients. The concept of a WAK is based on regeneration of a small volume of dialysate in a closed-loop. Removal of urea, the primary waste product of nitrogen metabolism, is the major challenge for the realization of a WAK since it is a molecule with low reactivity that is difficult to adsorb while it is the waste solute with the highest daily molar production. Currently, no efficient urea removal technology is available that allows for miniaturization of the WAK to a size and weight that is acceptable for patients to carry. Several urea removal strategies have been explored, including enzymatic hydrolysis by urease, electro-oxidation and sorbent systems. However, thus far, these methods have toxic side effects, limited removal capacity or slow removal kinetics. This review discusses different urea removal strategies for application in a wearable dialysis device, from both a chemical and a medical perspective.

Human factors testing of the Quanta SC+ hemodialysis system: An innovative system for home and clinic use

INTRODUCTION

Uptake rates of home hemodialysis are the lowest among all modality types, despite providing patients with clinical and quality of life benefits at a lower cost to providers. Currently, there is a need to develop dialysis systems that are appealing to patients while also being suitable for use across the continuum of care. The SC+ hemodialysis system was developed by Quanta Dialysis Technologies Ltd. to provide patients with a dialysis system that is small, simple to use, and powerful enough to deliver acceptable dialysis adequacy.

METHODS

As part of the SC+ design validation, human factors testing was performed with 17 Healthcare Professionals (nephrology nurses and healthcare assistants) and 15 Home Users (patients and caregivers). To assess usability and safety, the human factors testing involved between 4.5 and 6 hours of training and, after a period of training decay, a subsequent test session in which participants independently performed tasks on SC+.

FINDINGS

Between the two user groups, there were only 29 errors observed out of 1216 opportunities for errors, despite minimal training. Errors that did occur were minor and attributed to an initial lack of familiarity with the device; none were safety related.

DISCUSSION

Among prevalent dialysis patients and healthcare professionals, the SC+ hemodialysis system was easy to use, even with minimal training and a learning decay period, and had a high level of use safety. By taking into account human factors to optimize the user experience, SC+ has the potential to address systemic and patient barriers, allowing for wider self-care and home hemodialysis adoption.