Effects of Hemodiafiltration versus Conventional Hemodialysis in Children with ESKD: The HDF, Heart and Height Study

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.

Technical requirements and devices available for long-term hemodialysis in children-mind the gap!

Children requiring long-term kidney replacement therapy are a "rare disease" cohort. While the basic technical requirements for hemodialysis (HD) are similar in children and adults, key aspects of the child's cardiovascular anatomy and hemodynamic specifications must be considered. In this article, we describe the technical requirements for long-term HD therapy for children and the devices that are currently available around the world. We highlight the characteristics and major technical shortcomings of permanent central venous catheters, dialyzers, dialysis machines, and software available to clinicians who care for children. We show that currently available HD machines are not equipped with appropriately small circuits and sensitive control mechanisms to perform safe and effective HD in the youngest patients. Manufacturers limit their liability, and health regulatory agencies permit the use of devices, only in children according to the manufacturers' pre-specified weight limitations. Although registries show that 6-23% of children starting long-term HD weigh less than 15 kg, currently, there is only one long-term HD device that is cleared for use in children weighing 10 to 15 kg and none is available and labelled for use in children weighing less than 10 kg anywhere in the world. Thus, many children are being treated "off-label" and are subject to interventions delivered by medical devices that lack pediatric safety and efficacy data. Moreover, recent improvements in dialysis technology offered to adult patients are denied to most children. We, in turn, advocate for concerted action by pediatric nephrologists, industry, and health regulatory agencies to increase the development of dedicated HD machines and equipment for children.

Sodium handling in pediatric patients on maintenance dialysis

The risk of cardiovascular disease remains exceedingly high in pediatric patients with chronic kidney disease stage 5 on dialysis (CKD 5D). Sodium (Na+) overload is a major cardiovascular risk factor in this population, both through volume-dependent and volume-independent toxicity. Given that compliance with a Na+-restricted diet is generally limited and urinary Na+ excretion impaired in CKD 5D, dialytic Na+ removal is critical to reduce Na+ overload. On the other hand, an excessive or too fast intradialytic Na+ removal may lead to volume depletion, hypotension, and organ hypoperfusion. This review presents current knowledge on intradialytic Na+ handling and possible strategies to optimize dialytic Na+ removal in pediatric patients on hemodialysis (HD) and peritoneal dialysis (PD). There is increasing evidence supporting the prescription of lower dialysate Na+ in salt-overloaded children on HD, while improved Na+ removal may be achieved in children on PD with an individual adaptation of dwell time and volume and with icodextrin use during the long dwell.

Hemodiafiltration: Technical and Medical Insights

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

The effects of hospital and dialysis unit characteristics on hospitalizations for access-related complications among children on maintenance dialysis: a European, multicenter, observational, cross-sectional study

BACKGROUND

Previous studies investigating hospitalizations in dialysis patients have focused primarily on patient-centered factors. We analyzed the impact of hospital and dialysis unit characteristics on pediatric dialysis patients' hospitalizations for access-related complications (ARCs).

METHODS

This cross-sectional study involved 102 hemodialysis (HD) and 163 peritoneal dialysis (PD) patients. Data between July 2017 and July 2018 were analyzed.

RESULTS

Children's hospitals (CHs) had more pediatric nephrologists and longer PD experience (years) than general hospitals (GHs) (p = 0.026 and p = 0.023, respectively). A total of 53% of automated PD (APD) and 6% of continuous ambulatory PD (CAPD) patients were in CHs (p < 0.001). Ninety-three percent of APD and 69% of CAPD patients were treated in pediatric-specific PD units (p = 0.001). CHs had a higher prevalence in providing hemodiafiltration (HDF) than GHs (83% vs. 30%). Ninety-seven percent of HDF vs. 66% for conventional HD (cHD) patients, and 94% of patients with arteriovenous fistula (AVF) vs. 70% of those with central venous catheters (CVC), were dialyzed in pediatric-specific HD units (p = 0.001 and p = 0.016, respectively). Eighty patients (51 PD and 29 HD) had 135 (84 PD, 51 HD) hospitalizations. CAPD was an independent risk factor for hospitalizations for infectious ARCs (I-ARCs) (p = 0.009), and a health center's PD experience negatively correlated with CAPD patient hospitalizations for I-ARCs (p = 0.041). cHD and dialyzing in combined HD units significantly increased hospitalization risk for non-infectious (NI-)ARCs (p = 0.044 and p = 0.017, respectively).

CONCLUSIONS

CHs and pediatric-specific dialysis units have higher prevalence of APD and HDF use. Hospitalizations for I-ARCs in CAPD are lower in centers with longer PD experience, and pediatric HD units are associated with fewer hospitalizations due to NI-ARCs. A higher resolution version of the Graphical abstract is available as Supplementary information.

Echocardiogram screening in pediatric dialysis and transplantation

Transthoracic echocardiography is commonly used to identify structural and functional cardiac abnormalities that can be prevalent in childhood chronic kidney failure (KF). Left ventricular mass (LVM) increase is most frequently reported and may persist post-kidney transplant especially with hypertension and obesity. While systolic dysfunction is infrequently seen in childhood chronic KF, systolic strain identified by speckle tracking echocardiography has been frequently identified in dialysis and it can also persist post-transplant. Echocardiogram association with long-term outcomes has not been studied in childhood KF but there are many adult studies demonstrating associations between increased LVM, systolic dysfunction, strain, diastolic dysfunction, and cardiovascular events and mortality. There has been limited study of interventions to improve echocardiogram status. In childhood, improved blood pressure has been associated with better LVM, and conversion from hemodialysis to hemodiafiltration has been associated with better diastolic and systolic function. Whether long-term cardiac outcomes are also improved with these interventions is unclear. Echocardiography is a well-established technique, and regular use in childhood chronic KF seems justified. A case can be made to extend screening to include speckle tracking echocardiography and intradialytic studies in high-risk populations. Further longitudinal studies including these newer echocardiogram modalities, interventions, and long-term outcomes would help clarify recommendations for optimal use as a screening tool.

Nutritional and Anthropometric Indices in Children Receiving Haemodiafiltration vs Conventional Haemodialysis - The HDF, Heart and Height (3H) Study

BACKGROUND

The "HDF-Heart-Height" study showed that haemodiafiltration (HDF) is associated with improved growth compared to conventional haemodialysis (HD). We report a post-hoc analysis of this study assessing the effect of extracorporeal dialysis therapies on nutritional indices.

METHODS

107 children were included in the baseline cross-sectional analysis, of whom 79 (43 HD, 36 HDF) completed the 12-month follow-up. Height (Ht), optimal 'dry' weight (Wt), and body mass index (BMI) standard deviations scores (SDS), waist-to-hip ratio, des-acyl ghrelin (DAG), adiponectin, leptin, insulin-like growth factor-1 (IGF-1)-SDS and insulin were measured.

RESULTS

The levels of nutritional indices were comparable between HDF and HD patients at baseline and 12-month. On univariable analyses Wt-SDS positively correlated with leptin and IGF-1-SDS, and negatively with DAG, while Ht-SDS of the overall cohort positively correlated with IGF1-SDS and inversely with DAG and adiponectin. On multivariable analyses, higher 12-month Ht-SDS was inversely associated with baseline DAG (beta = -0.13 per 500 higher; 95%CI -0.22, -0.04; P = .004). Higher Wt-SDS at 12-month was positively associated with HDF modality (beta = 0.47 vs HD; 95%CI 0.12-0.83; P = .01) and inversely with baseline DAG (beta = -0.18 per 500 higher; 95%CI -0.32, -0.05; P = .006). Growth Hormone (GH) treated patients receiving HDF had higher annualized increase in Ht SDS compared to those on HD.

CONCLUSIONS

In children on HD and HDF both Wt- and Ht-SDS independently correlated with lower baseline levels of the anorexygenic hormone DAG. HDF may attenuate the resistance to GH, but further studies are required to examine the mechanisms linking HDF to improved growth.

Clinical performance, intermediate and long-term outcomes of high-volume hemodiafiltration in patients with kidney failure

Hemodiafiltration (HDF), in which both convective and diffusion methods are combined, yields an increased overall solute clearance compared with hemodialysis (HD), specifically for medium and larger molecular weight uremic toxins. Due to uncertainty in the treatment effects, the nephrology community still perceives the implementation of HDF and the achievement of high convective volume as complex. In this article, we review practical aspects of the implementation of HDF that can effectively deliver a high-volume HDF therapy and assure clinical performance to most patients. We also present an overview of the impact of high-volume HDF (compared to HD) on a series of relevant biochemical, patient-reported, and clinical outcomes, including uremic toxin removal, phosphate, Inflammation and oxidative stress, hemodynamic stability, cardiac outcomes, nutritional effects, health-related quality of life, morbidity, and mortality.

How peritoneal dialysis transforms the peritoneum and vasculature in children with chronic kidney disease-what can we learn for future treatment?

Children with chronic kidney disease (CKD) suffer from inflammation and reactive metabolite-induced stress, which massively accelerates tissue and vascular aging. Peritoneal dialysis (PD) is the preferred dialysis mode in children, but currently used PD fluids contain far supraphysiological glucose concentrations for fluid and toxin removal and glucose degradation products (GDP). While the peritoneal membrane of children with CKD G5 exhibits only minor alterations, PD fluids trigger numerous molecular cascades resulting in major peritoneal membrane inflammation, hypervascularization, and fibrosis, with distinct molecular and morphological patterns depending on the GDP content of the PD fluid used. PD further aggravates systemic vascular disease. The systemic vascular aging process is particularly pronounced when PD fluids with high GDP concentrations are used. GDP induce endothelial junction disintegration, apoptosis, fibrosis, and intima thickening. This review gives an overview on the molecular mechanisms of peritoneal and vascular transformation and strategies to improve peritoneal and vascular health in patients on PD.

Hidden risks associated with conventional short intermittent hemodialysis: A call for action to mitigate cardiovascular risk and morbidity

The development of maintenance hemodialysis (HD) for end stage kidney disease patients is a success story that continues to save many lives. Nevertheless, intermittent renal replacement therapy is also a source of recurrent stress for patients. Conventional thrice weekly short HD is an imperfect treatment that only partially corrects uremic abnormalities, increases cardiovascular risk, and exacerbates disease burden. Altering cycles of fluid loading associated with cardiac stretching (interdialytic phase) and then fluid unloading (intradialytic phase) likely contribute to cardiac and vascular damage. This unphysiologic treatment profile combined with cyclic disturbances including osmotic and electrolytic shifts may contribute to morbidity in dialysis patients and augment the health burden of treatment. As such, HD patients are exposed to multiple stressors including cardiocirculatory, inflammatory, biologic, hypoxemic, and nutritional. This cascade of events can be termed the dialysis stress storm and sickness syndrome. Mitigating cardiovascular risk and morbidity associated with conventional intermittent HD appears to be a priority for improving patient experience and reducing disease burden. In this in-depth review, we summarize the hidden effects of intermittent HD therapy, and call for action to improve delivered HD and develop treatment schedules that are better tolerated and associated with fewer adverse effects.

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.

Optimising the Nadroparin Dose for Thromboprophylaxis During Hemodialysis by Developing a Population Pharmacodynamic Model Using Anti-Xa Levels

INTRODUCTION

The optimal nadroparin dose in patients undergoing hemodialysis is difficult to determine in clinical practice. Anti-Xa levels ≥ 0.4 IU/mL and < 2.0 IU/mL are suggested to prevent thrombus formation within the extracorporeal circuit whilst minimizing bleeding risk. We aimed to characterize the variability in the association between dose and anti-Xa levels, identify patient and dialysis characteristics that explained this variability, and optimize nadroparin dosing based on the identified characteristics.

METHODS

Anti-Xa samples were collected in patients who received intravenous nadroparin as thromboprophylaxis during routine dialysis sessions. A population pharmacodynamic model was developed using non-linear mixed-effects modelling. The percentage of patients ≥ 0.4 IU/mL (efficacy) and < 2.0 IU/mL (safety) was simulated for different doses, patient and dialysis characteristics.

RESULTS

Patients (n = 137) were predominantly receiving standard hemodialysis (84.7% vs. hemodiafiltration 15.3%) and had a mean bodyweight of 76.3 kg (± 16.9). Lean body mass (LBM), mode of dialysis, and dialyzer partially explained between-subject variability in anti-Xa levels. Patients on hemodiafiltration and those receiving hemodialysis with a high LBM (≥ 80 kg) had a low probability (< 29%) of anti-Xa levels ≥ 0.4 IU/mL during the entire dialysis session. All patients, except hemodialysis patients with a low LBM (< 50 kg), had a high probability (> 70%) of peak anti-Xa levels < 2.0 IU/mL.

CONCLUSION

Mainly patients receiving hemodiafiltration and those receiving hemodialysis with a high LBM can benefit from a higher nadroparin dose than currently used in clinical practice, while having anti-Xa levels < 2.0 IU/mL.

Muscle-bone axis in children with chronic kidney disease: current knowledge and future perspectives

Bone and muscle tissue are developed hand-in-hand during childhood and adolescence and interact through mechanical loads and biochemical pathways forming the musculoskeletal system. Chronic kidney disease (CKD) is widely considered as both a bone and muscle-weakening disease, eventually leading to frailty phenotype, with detrimental effects on overall morbidity. CKD also interferes in the biomechanical communication between two tissues. Pathogenetic mechanisms including systemic inflammation, anorexia, physical inactivity, vitamin D deficiency and secondary hyperparathyroidism, metabolic acidosis, impaired growth hormone/insulin growth factor 1 axis, insulin resistance, and activation of renin-angiotensin system are incriminated for longitudinal uncoordinated loss of bone mineral content, bone strength, muscle mass, and muscle strength, leading to mechanical impairment of the functional muscle-bone unit. At the same time, CKD may also interfere in the biochemical crosstalk between the two organs, through inhibiting or stimulating the expression of certain osteokines and myokines. This review focuses on presenting current knowledge, according to in vitro, in vivo, and clinical studies, concerning the pathogenetic pathways involved in the muscle-bone axis, and suggests approaches aimed at preventing bone loss and muscle wasting in the pediatric population. Novel therapeutic targets for preserving musculoskeletal health in the context of CKD are also discussed.

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.

Nutritional status and volume control in adolescents on chronic hemodialysis

BACKGROUND

Pediatric patients on maintenance hemodialysis (HD) are at risk of both malnutrition and fluid overload. This pilot study aimed to assess correlates of normalized protein catabolic rate (nPCR) in adolescents on chronic HD, in particular fluid status markers.

METHODS

All patients aged 10-18 years on chronic HD in our center between 2017 and 2019 were enrolled. For each patient, mean nPCR was calculated and correlations with the following parameters investigated: dry body weight change in subsequent 3 months in kg (∆BW) and percentage of BW (∆BW%), change in body mass index (∆BMI), preHD systolic and diastolic blood pressure (SBP, DBP), residual urine output, biochemistry, and blood volume monitoring-derived first hour refill index (RI), calculated as ratio between ultrafiltration rate and reduction in relative blood volume in first hour of dialysis.

RESULTS

Seventy-nine nPCR determinations were collected in 23 patients, median age 14.8 years. nPCR significantly correlated with ∆BW, ∆BW%, ∆BMI, spKT/V, and preHD serum creatinine, and negatively correlated with age, DBP SDS (r=-0.466, p=0.025) and RI (r=-0.435, p=0.043). RI was significantly higher in patients with nPCR <1 than those with nPCR above this threshold: 3.2 (1.9-4.7) vs. 1.4 (0.7-1.8) ml/kg/h/% (p=0.021). At multivariable analysis, nPCR remained positively correlated with creatinine and spKt/V, and inversely correlated with RI.

CONCLUSIONS

nPCR is a significant predictor of weight change in adolescents on maintenance HD, and seems associated with creatinine and dialysis adequacy. Inverse correlation with RI suggests possible associations between malnutrition and fluid overload, but larger prospective studies are needed to confirm this. A higher resolution version of the Graphical abstract is available as Supplementary information.

Hemodiafiltration Is Associated With Reduced Inflammation and Increased Bone Formation Compared With Conventional Hemodialysis in Children: The HDF, Hearts and Heights (3H) Study

Background

Patients on dialysis have a high burden of bone-related comorbidities, including fractures. We report a post hoc analysis of the prospective cohort study HDF, Hearts and Heights (3H) to determine the prevalence and risk factors for chronic kidney disease-related bone disease in children on hemodiafiltration (HDF) and conventional hemodialysis (HD).

Methods

The baseline cross-sectional analysis included 144 children, of which 103 (61 HD, 42 HDF) completed 12-month follow-up. Circulating biomarkers of bone formation and resorption, inflammatory markers, fibroblast growth factor-23, and klotho were measured.

Results

Inflammatory markers interleukin-6, tumor necrosis factor-α, and high-sensitivity C-reactive protein were lower in HDF than in HD cohorts at baseline and at 12 months (P < .001). Concentrations of bone formation (bone-specific alkaline phosphatase) and resorption (tartrate-resistant acid phosphatase 5b) markers were comparable between cohorts at baseline, but after 12-months the bone-specific alkaline phosphatase/tartrate-resistant acid phosphatase 5b ratio increased in HDF (P = .004) and was unchanged in HD (P = .44). On adjusted analysis, the bone-specific alkaline phosphatase/tartrate-resistant acid phosphatase 5b ratio was 2.66-fold lower (95% confidence interval, −3.91 to −1.41; P < .0001) in HD compared with HDF. Fibroblast growth factor-23 was comparable between groups at baseline (P = .52) but increased in HD (P < .0001) and remained unchanged in HDF (P = .34) at 12 months. Klotho levels were similar between groups and unchanged during follow-up. The fibroblast growth factor-23/klotho ratio was 3.86-fold higher (95% confidence interval, 2.15–6.93; P < .0001) after 12 months of HD compared with HDF.

Conclusion

Children on HDF have an attenuated inflammatory profile, increased bone formation, and lower fibroblast growth factor-23/klotho ratios compared with those on HD. Long-term studies are required to determine the effects of an improved bone biomarker profile on fracture risk and cardiovascular health.

Commentary on the NICE guideline on renal replacement therapy and conservative management

NICE Guideline NG107, “Renal replacement therapy and conservative management” (Renal replacement therapy and conservative management (NG107); 2018:1–33) was published in October 2018 and replaced the existing NICE guideline CG125, “Chronic Kidney Disease (Stage 5): peritoneal dialysis” (Chronic kidney disease (stage 5): peritoneal dialysis | Guidance | NICE; 2011) and NICE Technology Appraisal TA48, “Guidance on home compared with hospital haemodialysis for patients with end-stage renal failure”(Guidance on home compared with hospital haemodialysis for patients with end-stage renal failure (Technology appraisal guideline TA48); 2002) The aim of the NICE guideline (NG107) was to provide guidance on renal replacement therapy (RRT), including dialysis, transplant and conservative care, for adults and children with CKD Stages 4 and 5. The guideline is extremely welcomed by the Renal Association and it offers huge value to patients, clinicians, commissioners and key stakeholders. It overlaps and enhances current guidance published by the Renal Association including “Haemodialysis” (Clinical practice guideline: Haemodialysis; 2019) which was updated in 2019 after the publication of the NICE guideline, “Peritoneal Dialysis in Adults and Children” (Clinical practice guideline: peritoneal Dialysis in adults and children; 2017) and “Planning, Initiation & withdrawal of Renal Replacement Therapy” (Clinical practice guideline: planning, initiation and withdrawal of renal replacement therapy; 2014) (at present there are no plans to update this guideline).

There are several strengths to NICE guideline NG107 and we agree with and support the vast majority of recommendation statements in the guideline. This summary from the Renal Association discusses some of the key highlights, controversies, gaps in knowledge and challenges in implementation. Where there is disagreement with a NICE guideline statement, we have highlighted this and a new suggested statement has been written.

Hemodiafiltration maintains a sustained improvement in blood pressure compared to conventional hemodialysis in children-the HDF, heart and height (3H) study

BACKGROUND

Hypertension is prevalent in children on dialysis and associated with cardiovascular disease. We studied the blood pressure (BP) trends and the evolution of BP over 1 year in children on conventional hemodialysis (HD) vs. hemodiafiltration (HDF).

METHODS

This is a post hoc analysis of the "3H - HDF-Hearts-Height" dataset, a multicenter, parallel-arm observational study. Seventy-eight children on HD and 55 on HDF who had three 24-h ambulatory BP monitoring (ABPM) measures over 1 year were included. Mean arterial pressure (MAP) was calculated and hypertension defined as 24-h MAP standard deviation score (SDS) ≥95th percentile.

RESULTS

Poor agreement between pre-dialysis systolic BP-SDS and 24-h MAP was found (mean difference - 0.6; 95% limits of agreement -4.9-3.8). At baseline, 82% on HD and 44% on HDF were hypertensive, with uncontrolled hypertension in 88% vs. 25% respectively; p < 0.001. At 12 months, children on HDF had consistently lower MAP-SDS compared to those on HD (p < 0.001). Over 1-year follow-up, the HD group had mean MAP-SDS increase of +0.98 (95%CI 0.77-1.20; p < 0.0001), whereas the HDF group had a non-significant increase of +0.15 (95%CI -0.10-0.40; p = 0.23). Significant predictors of MAP-SDS were dialysis modality (β = +0.83 [95%CI +0.51 - +1.15] HD vs. HDF, p < 0.0001) and higher inter-dialytic-weight-gain (IDWG)% (β = 0.13 [95%CI 0.06-0.19]; p = 0.0003).

CONCLUSIONS

Children on HD had a significant and sustained increase in BP over 1 year compared to a stable BP in those on HDF, despite an equivalent dialysis dose. Higher IDWG% was associated with higher 24-h MAP-SDS in both groups.

Monitoring dialysis adequacy: history and current practice

Dialysis adequacy for pediatric patients has largely followed the trends in adult dialysis by judging the success or adequacy of peritoneal or hemodialysis with urea kinetic modeling. While this provides a starting point to establish a dose of dialysis, it is clear that urea is only part of the picture. Many clinical parameters and interventions now have been identified that are just as impactful on mortality and morbidly as urea clearance. As such, our concept of adequacy is evolving to include non-urea parameters and assessing the impact that following an "adequate therapy" has on patient lives. As we move to a new era, we consider the impact these therapies have on patients and how it affects the quality of their lives; we must take these factors into consideration to achieve a therapy that is not just adequate, but livable.

Reducing the burden of cardiovascular disease in children with chronic kidney disease: prevention vs. damage limitation

Cardiovascular disease (CVD) is a life-limiting condition in patients with chronic kidney disease (CKD) and is rapidly progressive, especially in those with stage 5 CKD and on dialysis. Cardiovascular mortality, although reducing, remains at least 30 times higher than in the general pediatric population. The American Heart Association guidelines for cardiovascular risk reduction in high-risk pediatric patients has stratified pediatric CKD patients in the "high risk" category for the development of CVD, with associated pathological and/or clinical evidence for manifest coronary disease before 30 years of age. While improving patient survival is a key priority, other patient-related outcomes, such as psychosocial development, quality of life and growth are of major importance to children and their caregivers. Once vascular damage or calcification has developed, there are no data to suggest that they can be reversed. Treatments such as intensified dialysis and transplantation may attenuate the progression of subclinical cardiovascular disease, but no treatment to date has shown that the inexorable progression of CVD in CKD can be reversed. Thus, our management must focus on early diagnosis and robust preventative strategies to give our patients the best chance of optimal cardiovascular health and survival. In this review, the pathophysiology and importance of preventing the development of CVD in CKD is discussed.

Growth in children on kidney replacement therapy: a review of data from patient registries

Growth retardation is a major complication in children with chronic kidney disease (CKD) and on kidney replacement therapy (KRT). Conversely, better growth in childhood CKD is associated with an improvement in several hard morbidity-mortality endpoints. Data from pediatric international registries has demonstrated that improvements in the overall conservative management of CKD, the search for optimal dialysis, and advances in immunosuppression and kidney transplant techniques have led to a significant improvement of final height over time. Infancy still remains a critical period for adequate linear growth, and the loss of stature during the first years of life influences final height. Preliminary new original data from the European Society for Paediatric Nephrology/European Renal Association-European Dialysis and Transplant Association (ESPN/ERA-EDTA) Registry confirm an association between the final height and the height attained at 2 years in children on KRT.

Left ventricular strain and left atrial strain are impaired during hemodialysis in children

We aimed to investigate intradialytic changes in ventricular and atrial function using speckle tracking echocardiography (STE) in pediatric hemodialysis (HD). Children with HD vintage > 3 months were enrolled, and echocardiography was performed prior to, during, and after HD. STE was analyzed using GE EchoPAC. Left ventricular (LV) global longitudinal strain (GLS), strain rate (Sr), and mechanical dispersion index (MDI) were calculated as the average from 3 apical views; diastolic strain (Ds) and Sr from 4-chamber tracing; left atrial strain (LAS) and Sr from the 4- and 2-chamber views. A total of 15 patients were enrolled at a median age of 12 years (IQR 8, 16) and median HD vintage of 13 months (IQR 9, 25). GLS worsened during HD (- 15.8 ± 2.2% vs - 19.9 ± 1.9%, p < 0.001). Post-HD GLS was associated with BP decrease (coefficient = 0.62, p = 0.01). LV MDI and systolic Sr did not change. LV Ds progressively worsened (- 8.4% (- 9.2, - 8.0) vs - 11.9% (- 13.4, - 10.3), p < 0.001). LAS changes at mid-HD returned to baseline post-HD. Ds, DSr, LAS, LASr were not associated with BV removal or BP decrease (p > 0.1). In conclusions, intradialytic LV strain and LAS changes consistent with subclinical systolic and diastolic dysfunction were observed during HD in children. Changes in Ds, DSr, LAS, and LASr were not associated with BP change or BV removal and may be related to the disease progression. Longitudinal study using these novel indices may unfold the effect of these subclinical changes on long-term cardiovascular health in children requiring chronic HD.

Pathophysiology and consequences of arterial stiffness in children with chronic kidney disease

Changes in arterial structure and function are seen early in the course of chronic kidney disease (CKD) and have been causally associated with cardiovascular (CV) morbidity. Numerous potential injuries encompassing both traditional and uremia-specific CV risk factors can induce structural arterial changes and accelerate arterial stiffening. When the buffering capacity of the normally elastic arteries is reduced, damage to vulnerable microcirculatory beds can occur. Moreover, the resultant increase to cardiac afterload contributes to the development of left ventricular hypertrophy and cardiac dysfunction. Adult studies have linked arterial stiffness with increased risk of mortality, CV events, cognitive decline, and CKD progression. Pulse wave velocity (PWV) is currently the gold standard of arterial stiffness assessment but its measurement in children is challenging due to technical difficulties and physiologic aspects related to growth and poor standardization between algorithms for calculating PWV. Nevertheless, studies in pediatric CKD have reported increased arterial stiffness in children with advanced CKD, on dialysis, and after kidney transplantation. Development of arterial stiffness in children with CKD is closely related to mineral-bone disease and hypertension, but other factors may also play a significant role. The clinical relevance of accelerated arterial stiffness in childhood on cardiovascular outcomes in adult life remains unclear, and prospective studies are needed. In this review we discuss mechanisms leading to arterial stiffness in CKD and its clinical implications, along with issues surrounding the technical aspects of arterial stiffness assessment in children.

Evolution and change in paradigm of hemodialysis in children: a systematic review

BACKGROUND

There are similarities in hemodialysis (HD) between adults and children and also unique pediatric aspects. In this systematic review, we evaluated the existing HD literature, including vascular access, indications, parameters, and outcomes as a reflection on real-life HD practices.

METHODS

Medline, Embase, CINAHL, Web of Science, and Cochrane Library were systematically searched for literature on HD in children (1-20 years). Two reviewers independently assessed the literature and data on indications; vascular access, outcomes, and specific parameters for HD were extracted.

RESULTS

Fifty-four studies (8751 patients) were included in this review. Studies were stratified into age groups 1-5, 6-12, and 13-20 years based on median/mean age reported in the study, as well as era of publication (1990-2000, 2001-2010, and 2011-2019). Across all age groups, both arteriovenous fistulas and central venous catheters were utilized for vascular access. Congenital abnormalities and glomerulopathy were the most common HD indications. HD parameters including HD session duration, dialysate and blood flow rates, urea reduction ratio, and ultrafiltration were characterized for each age group, as well as common complications including catheter dysfunction and intradialytic hypotension. Median mortality rates were 23.3% (3.3), 7.6% (14.5), and 2.0% (3.0) in ages 1-5, 6-12, and 13-20 years, respectively. Median transplantation rates were 41.6% (38.3), 52.0% (32.0), and 21% (25.6) in ages 1-5, 6-12, and 13-20, respectively.

CONCLUSION

This comprehensive systematic review summarizes available literature on HD in children and young adults, including best vascular access, indications, technical aspects, and outcomes, and reflects on HD practices over the last three decades.

Bone Disease in CKD in Children

This manuscript discusses mineral and bone disorders of chronic kidney disease (MBD-CKD) in pediatric patients with special emphasis on the underlying pathophysiology, the causes and clinical profile of growth retardation, the alterations in the growth plate, the strategies to optimize growth and the medical recommendations for prevention and treatment.

Cardiovascular disease in childhood and adolescence: Lessons from children with chronic kidney disease

Children suffering from chronic kidney disease (CKD) have the apparent highest risk for the development of cardiovascular disease (CVD) at a young age. While symptoms of CVD are characteristically absent in childhood and adolescence, remodelling of the myocardium, medium and large-sized arteries and of the microcirculation is clinically significant and can be assessed with non-invasive technology. Kidney disease and its progression are the driver of CVD, mediated by an unparalleled accumulation of risk factors converging on several comorbid conditions including hypertension, anaemia, dyslipidaemia, disturbed mineral metabolism and chronic persistent inflammation. Large prospective paediatric cohorts studies have provided valuable insights into the pathogenesis and the progression of CKD-induced cardiovascular comorbidity and have characterised the cardiovascular phenotype in young patients. They have also provided the rationale for close monitoring of risk factors and have defined therapeutic targets. Recently discovered new biomarkers could help identify the individual risk for CVD. Prevention of CVD by aggressive therapy of modifiable risk factors is essential to enable long-term survival of young patients with CKD.

When do children need kidney replacement therapy?

Kidney replacement therapy (KRT) can provide lifesaving support for children with severely impaired kidney function. The decision about who needs KRT and when is often complex. Many acute kidney problems will resolve with conservative maanagemenent but some children with chronic or acute kidney impairment will find themselves in a position where KRT is required either as a bridge to recovery or kidney transplantation. Less commonly, children with metabolic disorders may find that the ability of their own kidneys is overwhelmed by excessive production of certain metabolites. These children may also benefit from short term KRT. This article aims to help paediatricians in training understand which children need kidney replacement therapy, the various types of treatment available, and when they are used.

Comparison between citrate and acetate dialysate in chronic online hemodiafiltration: A short-term prospective study in pediatric settings

BACKGROUND

The use of citrate in chronic hemodialysis to acidify dialysis solutions, in replacement of acetate, began in the 2000's. The purpose of the following study is to determine whether this change represents a better alternative regarding short-term tolerance, efficiency and biocompatibility of chronic renal replacement therapy (RRT) in pediatric patients.

METHODS

A monocentric prospective observational study was conducted in the pediatric dialysis department of Nancy (France) between December 1st, 2014 and January 25, 2015 on a cohort of pediatric patients under predilution on-line hemodiafiltration (olHDF). Sessions were analysed during two study periods of 14 days: a first period during which dialysis solutions were acidified using acetate and a second during which solutes were acidified using citrate. These periods were separated by a washout period of 28 days on citrate solution. Each patient served as his own control.

RESULTS

Dialysis clinical tolerance seems better under citrate regimen, with no statistical significance. No benefit was brought out regarding the prevention of coagulation accidents in the extracorporeal circuit under citrate regimen. The efficiency of olHDF sessions was similar between periods, both in terms of uremic toxins clearance and medium-molecular-weight molecules (MMWM) removal. The evolution of several biological parameters seemed favourable over the citrate period: increase in pre-dialysis serum bicarbonate, stability of plasma hemoglobin and decrease in erythropoietin resistance index (ERI). However, differences in the variation of these parameters between the two periods were not significant. No severe and/or symptomatic hypocalcemia occurred.

CONCLUSION

The use of citrate instead of acetate in dialysis and substitution solutions appears in the short term as a safe alternative for chronic online hemodiafiltration in children.

Plasma pseudouridine levels reflect body size in children on hemodialysis

BACKGROUND

Dialysis in children as well as adults is prescribed to achieve a target spKt/V_urea, where V_urea is the volume of distribution of urea. Waste solute production may however be more closely correlated with body surface area (BSA) than V_urea which rises in proportion with body weight. Plasma levels of waste solutes may thus be higher in smaller patients when targeting spKt/V_urea since they have higher BSA relative to body weight. This study measured levels of pseudouridine (PU), a novel marker solute whose production is closely proportional to BSA, to test whether prescription of dialysis to a target spKt/V_urea results in higher plasma levels of PU in smaller children.

METHODS

PU and urea nitrogen (ureaN) were measured in plasma and dialysate at the midweek hemodialysis session in 20 pediatric patients, with BSA ranging from 0.65-1.87m². Mathematical modeling was employed to estimate solute production rates and average plasma solute levels.

RESULTS

The dialytic clearance (K_d) of PU was proportional to that of ureaN (average K_dPU/K_dUreaN 0.69 ± 0.13, r² 0.84, p < 0.001). Production of PU rose in proportion with BSA (r² 0.57, p < 0.001). The pretreatment plasma level of PU was significantly higher in smaller children (r² 0.20, p = 0.051) while the pretreatment level of ureaN did not vary with size.

CONCLUSIONS

Prescribing dialysis based on urea kinetics may leave uremic solutes at higher levels in small children. Measurement of a solute produced proportional to BSA may provide a better index of dialysis adequacy than measurement of urea.

Strategies for Optimizing Growth in Children With Chronic Kidney Disease

Growth failure is a hallmark in children with chronic kidney disease (CKD). Therefore, early diagnosis and adequate management of growth failure is of utmost importance in these patients. The risk of severe growth retardation is the higher the younger the child is, which places an additional burden on patients and their families and hampers the psychosocial integration of these children. Careful monitoring of growth, and effective interventions are mandatory to prevent and treat growth failure in children with CKD at all ages and all stages of kidney failure. Early intervention is critical, as all therapeutic interventions are much more effective if they are started prior to the initiation of dialysis. Prevention and treatment of growth failure focuses on: (i) preservation of renal function, e.g., normalization of blood pressure and proteinuria by use of inhibitors of the renin-angiotensin aldosterone system, (ii) adequate energy intake, including tube feeding or gastrostomy in case of persisting malnutrition, (iii) substitution of water and electrolytes, especially in children with renal malformation, (iv) correction of metabolic acidosis, (v) control of parathyroid hormone levels within the CKD-dependent target range, (vi) use of recombinant human growth hormone in cases of persistent growth failure, and, (vii) early/preemptive kidney transplantation using steroid-minimizing immunosuppressive protocols in children with end-stage CKD. This review discusses these measures based on recent guidelines.

Haemodiafiltration does not lower protein-bound uraemic toxin levels compared with haemodialysis in a paediatric population

Background

Haemodiafiltration (HDF) is accepted to effectively lower plasma levels of middle molecules in the long term, while data are conflicting with respect to the additive effect of convection on lowering protein-bound uraemic toxins (PBUTs). Here we compared pre-dialysis β2-microglobulin (β2M) and PBUT levels and the percentage of protein binding (%PB) in children on post-dilution HDF versus conventional high- (hf) or low-flux (lf) haemodialysis (HD) over 12 months of treatment.

Methods

In a prospective multicentre, non-randomized parallel-arm intervention study, pre-dialysis levels of six PBUTs and β2M were measured in children (5–20 years) on post-HDF (n = 37), hf-HD (n = 42) and lf-HD (n = 18) at baseline and after 12 months. Analysis of variance was used to compare levels and %PB in post-HDF versus conventional hf-HD and lf-HD cross-sectionally at 12 months and longitudinal from baseline to 12 months.

Results

For none of the PBUTs, no difference was found in either total and free plasma levels or %PB between post-HDF versus the hf-HD and lf-HD groups. Children treated with post-HDF had lower pre-dialysis β2M levels [median 23.2 (21.5; 26.6) mg/dL] after 12 months versus children on hf-HD [P&lt;0.01; 35.2 (29.3; 41.2) mg/dL] and children on lf-HD [P&lt;0.001; 47.2 (34.3; 53.0) mg/dL]. While β2M levels remained steady in the hf-HD and lf-HD group, a decrease in β2M was demonstrated for children on post-HDF (P&lt;0.01).

Conclusions

While post-HDF successfully decreased β2M, no additive effect on PBUT over 12 months of treatment was found. PBUT removal is complex and hampered by several factors. In children, these factors might be different from adults and should be explored in future research.

Determinants of Statural Growth in European Children With Chronic Kidney Disease: Findings From the Cardiovascular Comorbidity in Children With Chronic Kidney Disease (4C) Study

Failure of statural growth is one of the major long-term sequelae of chronic kidney disease (CKD) in children. In recent years effective therapeutic strategies have become available that lead to evidence based practice recommendations. To assess the current growth performance of European children and adolescents with CKD, we analyzed a cohort of 594 patients from 12 European countries who were followed prospectively for up to 6 years in the 4C Study. While all patients were on conservative treatment with a mean estimated glomerular filtration rate of 28 ml/min/1.73 m² at study entry, 130 children commenced dialysis during the observation period. At time of enrolment the mean height standard deviation score (SDS) was -1.57; 36% of patients had a height below the third percentile. The prevalence of growth failure varied between countries from 7 to 44% Whereas patients on conservative treatment showed stable growth, height SDS gradually declined on those on dialysis. Parental height, pubertal status and treatment with recombinant growth hormone (GH) were positively, and the diagnosis of syndromic disease and CKD stage were negatively associated with height SDS during the observation period. Unexpectedly, higher body mass index (BMI) SDS was associated with lower height SDS both at enrolment and during follow up. Renal anemia, metabolic acidosis, and hyperparathyroidism were mostly mild and not predictive of growth rates by multivariable analysis. GH therapy was applied in only 15% of growth retarded patients with large variation between countries. When adjusting for all significant covariates listed above, the country of residence remained a highly significant predictor of overall growth performance. In conclusion, growth failure remains common in European children with CKD, despite improved general management of CKD complications. The widespread underutilization of GH, an approved efficacious therapy for CKD-associated growth failure, deserves further exploration.