Modification of Dialysate Na+ Concentration but not Ultrafiltration or Dialysis Treatment Time Affects Tissue Na+ Deposition in Patients on Hemodialysis

Introduction

Tissue Na+ overload is present in patients receiving hemodialysis (HD) and is associated with cardiovascular mortality. Strategies to actively modify tissue Na+ amount in these patients by adjusting the HD regimen have not been evaluated.

Methods

In several substudies, including cross-sectional analyses (n = 75 patients on HD), a cohort study and a cross-over interventional study (n = 10 patients each), we assessed the impact of ultrafiltration (UF) volume, prolongation of dialysis treatment time, and modification of dialysate Na+ concentration on tissue Na+ content using 23Na magnetic resonance imaging (23Na-MRI).

Results

In the cross-sectional analysis of our patients on HD, differences in dialysate sodium concentration ([Na+]) were associated with changes in tissue Na+ content, whereas neither UF volume nor HD treatment time affected tissue Na+ amount. Skin Na+ content was lower in 17 patients on HD, with dialysate [Na+] of <138 mmol/l compared to 58 patients dialyzing at ≥138 mmol/l (20.7 ± 7.3 vs. 26.0 ± 8.8 arbitrary units [a.u.], P < 0.05). In the cohort study, intraindividual prolongation of HD treatment time was not associated with a reduction in tissue Na+ content. Corresponding to the observational data, intraindividual modification of dialysate [Na+] from 138 to 142 to 135 mmol/l resulted in concordant changes in skin Na+ (24.3 ± 7.6 vs. 26.3 ± 8.0 vs. 20.8 ± 5.6 a.u, P < 0.05 each), whereas no significant change in muscle Na+ occurred.

Conclusion

Solely adjustment of dialysate [Na+] had a reproducible impact on tissue Na+ content. 23Na-MRI could be utilized to monitor the effectiveness of dialysate [Na+] modifications in randomized-controlled outcome trials.

The role of intra- and interdialytic sodium balance and restriction in dialysis therapies

The relationship between sodium, blood pressure and extracellular volume could not be more pronounced or complex than in a dialysis patient. We review the patients' sources of sodium exposure in the form of dietary salt intake, medication administration, and the dialysis treatment itself. In addition, the roles dialysis modalities, hemodialysis types, and dialysis fluid sodium concentration have on blood pressure, intradialytic symptoms, and interdialytic weight gain affect patient outcomes are discussed. We review whether sodium restriction (reduced salt intake), alteration in dialysis fluid sodium concentration and the different dialysis types have any impact on blood pressure, intradialytic symptoms, and interdialytic weight gain.

Sodium intake and urinary losses in children on dialysis: a European multicenter prospective study

BACKGROUND

Sodium (Na) balance is unexplored in dialyzed children. We assessed a simplified sodium balance (sNaB) and its correlates in pediatric patients receiving maintenance dialysis.

METHODS

Patients < 18 years old on hemodialysis (HD) or peritoneal dialysis (PD) in six European Pediatric Dialysis Working Group centers were recruited. sNaB was calculated from enteral Na, obtained by a 3-day diet diary, Na intake from medications, and 24-h urinary Na (uNa). Primary outcomes were systolic blood pressure and diastolic blood pressure standard deviation scores (SBP and DBP SDS), obtained by 24-h ambulatory blood pressure monitoring or office BP according to age, and interdialytic weight gain (IDWG).

RESULTS

Forty-one patients (31 HD), with a median age of 13.3 (IQR 5.2) years, were enrolled. Twelve patients (29.3%) received Na-containing drugs, accounting for 0.6 (0.7) mEq/kg/day. Median total Na intake was 1.5 (1.1) mEq/kg/day, corresponding to 60.6% of the maximum recommended daily intake for healthy children. Median uNa and sNaB were 0.6 (1.8) mEq/kg/day and 0.9 (1.7) mEq/kg/day, respectively. The strongest independent predictor of sNaB in the cohort was urine output. In patients receiving HD, sNaB correlated with IDWG, pre-HD DBP, and first-hour refill index, a volume index based on blood volume monitoring. sNaB was the strongest predictor of IDWG in multiple regression analysis (β = 0.63; p = 0.005). Neither SBP SDS nor DBP SDS correlated with sNaB.

CONCLUSIONS

Na intake is higher than uNa in children on dialysis, and medications may be an important source of Na. sNaB is best predicted by urine output in the population, and it is a significant independent predictor of IDWG in children on HD. A higher resolution version of the Graphical abstract is available as Supplementary information.

Quality of Life and Related Factors in Patients Undergoing Renal Replacement Therapy at the Hospital General Universitario de Ciudad Real: Cross Sectional Descriptive Observational Study

Background: The aim of the present study was to determine the relationship between the quality of life of patients on renal replacement therapy and the Symptomatology they presented. Methods: Cross-sectional descriptive observational study: quality of life was assessed by means of the KDQOL-SF questionnaire, Symptomatology by the Palliative Care Outcome Scale-Symptoms Renal questionnaire, and sociodemographic and clinical data of patients in the Hemodialysis Unit (HD) of the Hospital General Universitario de Ciudad Real (HGUCR) by means of personal interviews and clinical history data. Results: A total of 105 patients participated in the study, 63 (60.57%) men and 42 (40.38%) female. The mean age was 62.5 dt (14.84) years. Of these, 43 (41%) were on peritoneal dialysis and 62 (59%) were on hemodialysis. The mean quality of life score was 44.89 dt (9.73). People on hemodialysis treatment presented a better quality of life than those on PD treatment: 49.66 dt (9.73) vs. 38.13 dt (9.12) t = 7.302, p < 0.001. A higher score on the symptom impairment scale (post-renal) correlated with worse scores on the total quality of life score: r = −0.807, p < 0.001. It was observed that those who improved the distress symptom scored better on the total quality of life questionnaire: 50.22 dt (8.44) vs. 46.42 dt (9.05), p < 0.001. Conclusions: The presence and management of the large number of symptoms that appear as side effects, such as distress or depression, could determine changes in some components of quality of life.

Chinese Clinical Practice Guideline for the Management of "CKD-PeriDialysis"-the Periods Prior to and in the Early-Stage of Initial Dialysis

The National Experts Group on Nephrology have developed these guidelines to improve the management of pre-dialysis and initial dialysis patients with chronic kidney disease (CKD) (two periods contiguous with dialysis initiation termed here 'PeriDialysis CKD'). The pre-dialysis period is variable, whereas the initial dialysis period is more fixed at 3 months to 6 months after initiating dialysis. The new concept and characteristics of 'CKD-PeriDialysis' are proposed in the guideline. During the CKD-PeriDialysis period, the incidence rate of complications, mortality and treatment cost significantly increases and the glomerular filtration rate (GFR) rapidly decreases, which requires intensive management. The guideline systematically and comprehensively elaborates the recommendations for indicators to be used in for disease evaluation, timing and mode selection of renal replacement therapy, dialysis adequacy evaluation, and diagnosis and treatment of common PeriDialysis complications. Finally, future research directions of CKD-PeriDialysis are proposed. CKD-PeriDialysis management is a difficult clinical issue in kidney disease, and the development and implementation of these guidelines is important to improve the management of CKD-PeriDialysis patients in China, which could ultimately improve survival rates and quality of life, and reduce the medical burden.

Role of Antihypertensives in End-Stage Renal Disease: A Systematic Review

The primary goal of this research is to identify the factors of intradialytic hypertension in hemodialysis patients and stabilize blood pressure (BP) even without antihypertensive medicines. There are various treatment alternatives for lowering BP in these patients, many of which do not require extra pharmacological therapy (e.g. long, slow hemodialysis; short, daily hemodialysis; nocturnal hemodialysis; or, most effectively, dietary salt and fluid restriction in addition to the reduction of dialysate sodium concentration). These parameters provide good monitoring of BP, even with previously diagnosed hypertension. The adjustment of the extracellular volume with a low incidence of intradialytic hypotensive episodes is the most plausible explanation for this outcome.

We did a systematic evaluation of all published articles since 1994 to evaluate antihypertensive drug outcomes in hemodialysis patients. All articles were searched in the English language using PubMed and Google Scholar databases. The screening techniques, study selection, data extraction procedures, and risk evaluation of bias were done using specified criteria and overseen by one of the senior writers with the application of quality assessment tools to the final articles. Data were searched using regular and MeSH (Medical Subject Headings) keywords. Although substantial developments have emerged in the medical field, there is still a significant knowledge gap in the sector, particularly when it comes to BP guidelines and therapy choices for hypertensive hemodialysis patients. Until additional data are available, we should treat hypertension in hemodialysis with the use of active pursuit of euvolemia using dry weight probing and reduction of salt excess.

Management of hypertension and renin-angiotensin-aldosterone system blockade in adults with diabetic kidney disease: Association of British Clinical Diabetologists and the Renal Association UK guideline update 2021

People with type 1 and type 2 diabetes are at risk of developing progressive chronic kidney disease (CKD) and end-stage kidney failure. Hypertension is a major, reversible risk factor in people with diabetes for development of albuminuria, impaired kidney function, end-stage kidney disease and cardiovascular disease. Blood pressure control has been shown to be beneficial in people with diabetes in slowing progression of kidney disease and reducing cardiovascular events. However, randomised controlled trial evidence differs in type 1 and type 2 diabetes and different stages of CKD in terms of target blood pressure. Activation of the renin-angiotensin-aldosterone system (RAAS) is an important mechanism for the development and progression of CKD and cardiovascular disease. Randomised trials demonstrate that RAAS blockade is effective in preventing/ slowing progression of CKD and reducing cardiovascular events in people with type 1 and type 2 diabetes, albeit differently according to the stage of CKD. Emerging therapy with sodium glucose cotransporter-2 (SGLT-2) inhibitors, non-steroidal selective mineralocorticoid antagonists and endothelin-A receptor antagonists have been shown in randomised trials to lower blood pressure and further reduce the risk of progression of CKD and cardiovascular disease in people with type 2 diabetes. This guideline reviews the current evidence and makes recommendations about blood pressure control and the use of RAAS-blocking agents in different stages of CKD in people with both type 1 and type 2 diabetes.

OUP accepted manuscript

Patients on chronic hemodialysis are counseled to reduce dietary sodium intake to limit their thirst and consequent interdialytic weight gain (IDWG), chronic volume overload and hypertension. Low-sodium dietary trials in hemodialysis are sparse and mostly indicate that dietary education and behavioral counseling are ineffective in reducing sodium intake and IDWG. Additional nutritional restrictions and numerous barriers further complicate dietary adherence. A low-sodium diet may also reduce tissue sodium, which is positively associated with hypertension and left ventricular hypertrophy. A potential alternative or complementary approach to dietary counseling is home delivery of low-sodium meals. Low-sodium meal delivery has demonstrated benefits in patients with hypertension and congestive heart failure but has not been explored or implemented in patients undergoing hemodialysis. The objective of this review is to summarize current strategies to improve volume overload and provide a rationale for low-sodium meal delivery as a novel method to reduce volume-dependent hypertension and tissue sodium accumulation while improving quality of life and other clinical outcomes in patients undergoing hemodialysis.

The roles of sodium and volume overload on hypertension in chronic kidney disease

Chronic kidney disease (CKD) is associated with increased risk of cardiovascular (CV) events, and the disease burden is rising rapidly. An important contributor to CV events and CKD progression is high blood pressure (BP). The main mechanisms of hypertension in early and advanced CKD are renin-angiotensin system activation and volume overload, respectively. Sodium retention is well known as a factor for high BP in CKD. However, a BP increase in response to total body sodium or volume overload can be limited by neurohormonal modulation. Recent clinical trial data favoring intensive BP lowering in CKD imply that the balance between volume and neurohormonal control could be revisited with respect to the safety and efficacy of strict volume control when using antihypertensive medications. In hemodialysis patients, the role of more liberal use of antihypertensive medications with the concept of functional dry weight for intensive BP control must be studied.

Impact of Bioelectrical Impedance-Guided Fluid Management and Vitamin D Supplementation on Left Ventricular Mass in Patients Receiving Peritoneal Dialysis: A Randomized Controlled Trial

RATIONALE & OBJECTIVES

Hypervolemia and vitamin D (Vit D) deficiency occur frequently in patients receiving peritoneal dialysis and may contribute to left ventricular hypertrophy (LVH). The effect of bioimpedance analysis-guided volume management or Vit D supplementation on LV mass among those receiving peritoneal dialysis is uncertain.

STUDY DESIGN

Two-by-two factorial randomized controlled trial.

SETTING & PARTICIPANTS

Sixty-five patients receiving chronic peritoneal dialysis.

INTERVENTION

BIA-guided volume management versus usual care and oral cholecalciferol 50,000u weekly for 8 weeks followed by 10,000u weekly for 44 weeks or matching placebo.

OUTCOMES

Change in left ventricular mass at one-year measured by cardiac magnetic resonance imaging.

RESULTS

Total body water decreased by 0.9L (standard deviation: 2.4) in the BIA group compared to a 1.5L (± 3.4) increase in the usual care group (adjusted between group difference: -2.4L [95% confidence interval: -4.1, -0.68], p=0.01). Left ventricular mass increased by 1.3g (± 14.3) in the BIA group and decreased by 2.4g (±37.7) in the usual care group (between group difference; +2.2g [-13.9, 18.3], p=0.78). Serum 25-OH Vit D concentration increased by a mean of 17.2 nmol/L (standard deviation: 30.8 nmol/L) in the cholecalciferol group and declined by 8.2 nmol/L (±24.3 nmol/L) in the placebo group (between group difference: 28.3 nmol/L [95% confidence interval 17.2, 39.4]; p<0.001). Left ventricular mass decreased by 3.0g (± 28.1g) in the cholecalciferol group and increased by 2.0g (±31.2g) in the placebo group (between group difference; -4.5g [-20.4, 11.5], p=0.58).

LIMITATIONS

Relatively small sample size with larger than expected variation in change in left ventricular mass.

CONCLUSIONS

BIA-guided volume management had a modest impact on volume status with no effect on the change in LV mass. Vitamin D supplementation increased serum Vit D concentration but had no effect on left ventricular mass.

Relationship between doses of antihypertensive drugs and left ventricular mass index changes in hemodialysis patients in a Japanese cohort

Left ventricular hypertrophy commonly occurs in dialysis patients and is associated with a risk of developing cardiovascular disease events and all-cause mortality. Although hypertension treatment reduces left ventricular mass index (LVMI) in hemodialysis patients, the relationships of prescription pattern, dose, and changes in the dose of antihypertensive drugs with LVMI have not been completely elucidated. Here, we hypothesized that volume reduction would lead to a decrease in the antihypertensive drug dose and subsequently to a reduction in LVMI; conversely, fluid retention would lead to an increase in the antihypertensive drug use and, subsequently, to LVMI progression. To assess this hypothesis, we investigated the relationship between changes in the dose of antihypertensive drugs and subsequent changes in LVMI in 240 patients who had just started hemodialysis using a retrospective hemodialysis cohort in Japan. Using multiple linear regression analysis, we assessed the association between changes in the antihypertensive drug dose over 1 year after hemodialysis initiation and changes in LVMI during this period. A decrease and an increase in the antihypertensive drug dose were significantly associated with a reduction in LVMI (vs. no change; β  = – 17.386, p < .001) and LVMI progression (vs. no change; β  = 16.192, p < .001), respectively. In conclusion, our findings suggested that volume reduction, leading to a decrease in the use of antihypertensive drugs, is a therapeutic strategy in patients undergoing hemodialysis to prevent LVMI progression.

Altered dietary salt intake for people with chronic kidney disease

BACKGROUND

Evidence indicates that reducing dietary salt may reduce the incidence of heart disease and delay decline in kidney function in people with chronic kidney disease (CKD). This is an update of a review first published in 2015.

OBJECTIVES

To evaluate the benefits and harms of altering dietary salt for adults with CKD.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 6 October 2020 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials comparing two or more levels of salt intake in adults with any stage of CKD.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies for eligibility, conducted risk of bias evaluation and evaluated confidence in the evidence using GRADE. Results were summarised using random effects models as risk ratios (RR) for dichotomous outcomes or mean differences (MD) for continuous outcomes, with 95% confidence intervals (CI).

MAIN RESULTS

We included 21 studies (1197 randomised participants), 12 in the earlier stages of CKD (779 randomised participants), seven in dialysis (363 randomised participants) and two in post-transplant (55 randomised participants). Selection bias was low in seven studies, high in one and unclear in 13. Performance and detection biases were low in four studies, high in two, and unclear in 15. Attrition and reporting biases were low in 10 studies, high in three and unclear in eight. Because duration of the included studies was too short (1 to 36 weeks) to test the effect of salt restriction on endpoints such as death, cardiovascular events or CKD progression, changes in salt intake on blood pressure and other secondary risk factors were examined. Reducing salt by mean -73.51 mmol/day (95% CI -92.76 to -54.27), equivalent to 4.2 g or 1690 mg sodium/day, reduced systolic/diastolic blood pressure by -6.91/-3.91 mm Hg (95% CI -8.82 to -4.99/-4.80 to -3.02; 19 studies, 1405 participants; high certainty evidence). Albuminuria was reduced by 36% (95% CI 26 to 44) in six studies, five of which were carried out in people in the earlier stages of CKD (MD -0.44, 95% CI -0.58 to -0.30; 501 participants; high certainty evidence). The evidence is very uncertain about the effect of lower salt intake on weight, as the weight change observed (-1.32 kg, 95% CI -1.94 to -0.70; 12 studies, 759 participants) may have been due to fluid volume, lean tissue, or body fat. Lower salt intake may reduce extracellular fluid volume in the earlier stages of CKD (-0.87 L, 95% CI -1.17 to -0.58; 3 studies; 187 participants; low certainty evidence). The evidence is very uncertain about the effect of lower salt intake on reduction in antihypertensive dose (RR 2.45, 95% CI 0.98 to 6.08; 8 studies; 754 participants). Lower salt intake may lead to  symptomatic hypotension (RR 6.70, 95% CI 2.40 to 18.69; 6 studies; 678 participants; moderate certainty evidence). Data were sparse for other types of adverse events.

AUTHORS' CONCLUSIONS

We found high certainty evidence that salt reduction reduced blood pressure in people with CKD, and albuminuria in people with earlier stage CKD in the short-term. If such reductions could be maintained long-term, this effect may translate to clinically significant reductions in CKD progression and cardiovascular events. Research into the long-term effects of sodium-restricted diet for people with CKD is warranted.

Antihypertensive Therapy in Patients Receiving Maintenance Hemodialysis: A Narrative Review of the Available Clinical-Trial Evidence

BACKGROUND

Blood pressure (BP)-lowering with the use of antihypertensive drugs appears to protect the cardiovascular (CV) system in hemodialysis patients. However, the optimal treatment algorithm of hypertension remains elusive; extrapolation of clinical-trial evidence from the general population may not be optimal.

METHODS

For this narrative review, we searched the Medline/PubMed database (inception to August 01, 2019) to identify randomized clinical trials evaluating the efficacy of antihypertensive drugs on CV outcomes and mortality in patients on hemodialysis.

RESULTS

Randomized trials with angiotensin-converting-enzyme-inhibitors (ACEIs) or angiotensinreceptor- blockers (ARBs) failed to provide consistent cardioprotection. β-blockers may provide a more consistent CV benefit. Although some early clinical trials have shown that mineralocorticoid-receptorantagonists (MRAs) reduce CV mortality, the associated risk of hyperkalemia raises important safety concerns on the use of MRAs as add-on therapy.

CONCLUSION

Our first-line therapy of hypertension in hemodialysis is the assessment and management of dry-weight and optimization of dialysis prescription. Based on the available clinical-trial evidence, we prescribe atenolol 3 times/week after dialysis as the first-line pharmacological option of hypertension to our patients without specific indications for other agents. Long-acting dihydropyridines and ACEIs/ARBs are our second-line and third-line choices, respectively. We avoid using MRAs and await results from ongoing trials testing their safety and efficacy. In patients receiving maintenance hemodialysis, randomized trials are clearly warranted in order to define BP targets and the comparative effectiveness of different antihypertensive drugs.

Volume overload in hemodialysis: diagnosis, cardiovascular consequences, and management

Volume overload in haemodialysis (HD) patients associates with hypertension and cardiac dysfunction and is a major risk factor for all-cause and cardiovascular mortality in this population. The diagnosis of volume excess and estimation of dry weight is based largely on clinical criteria and has a notoriously poor diagnostic accuracy. The search for accurate and objective methods to evaluate dry weight and to diagnose subclinical volume overload has been intensively pursued over the last 3 decades. Most methods have not been tested in appropriate clinical trials and their usefulness in clinical practice remains uncertain, except for bioimpedance spectroscopy and lung ultrasound (US). Bioimpedance spectroscopy is possibly the most widely used method to subjectively quantify fluid distributions over body compartments and produces reliable and reproducible results. Lung US provides reliable estimates of extravascular water in the lung, a critical parameter of the central circulation that in large part reflects the left ventricular end-diastolic pressure. To maximize cardiovascular tolerance, fluid removal in volume-expanded HD patients should be gradual and distributed over a sufficiently long time window. This review summarizes current knowledge about the diagnosis, prognosis and treatment of volume overload in HD patients.

Sodium, volume and pressure control in haemodialysis patients for improved cardiovascular outcomes

Chronic volume overload is pervasive in patients on chronic haemodialysis and substantially increases the risk of cardiovascular death. The rediscovery of the three-compartment model in sodium metabolism revolutionizes our understanding of sodium (patho-)physiology and is an effect modifier that still needs to be understood in the context of hypertension and end-stage kidney disease. Assessment of fluid overload in haemodialysis patients is central yet difficult to achieve, because traditional clinical signs of volume overload lack sensitivity and specificity. The highest all-cause mortality risk may be found in haemodialysis patients presenting with high fluid overload but low blood pressure before haemodialysis treatment. The second highest risk may be found in patients with both high blood pressure and fluid overload, while high blood pressure but normal fluid overload may only relate to moderate risk. Optimization of fluid overload in haemodialysis patients should be guided by combining the traditional clinical evaluation with objective measurements such as bioimpedance spectroscopy in assessing the risk of fluid overload. To overcome the tide of extracellular fluid, the concept of time-averaged fluid overload during the interdialytic period has been established and requires possible readjustment of a negative target post-dialysis weight. ²³Na-magnetic resonance imaging studies will help to quantitate sodium accumulation and keep prescribed haemodialytic sodium mass balance on the radar. Cluster-randomization trials (e.g. on sodium removal) are underway to improve our therapeutic approach to cardioprotective haemodialysis management.

An update review of intradialytic hypotension: concept, risk factors, clinical implications and management

Intradialytic hypotension (IDH) is a frequent and serious complication of chronic haemodialysis, linked to adverse long-term outcomes including increased cardiovascular and all-cause mortality. IDH is the end result of the interaction between ultrafiltration rate (UFR), cardiac output and arteriolar tone. Thus excessive ultrafiltration may decrease the cardiac output, especially when compensatory mechanisms (heart rate, myocardial contractility, vascular tone and splanchnic flow shifts) fail to be optimally recruited. The repeated disruption of end-organ perfusion in IDH may lead to various adverse clinical outcomes affecting the heart, central nervous system, kidney and gastrointestinal system. Potential interventions to decrease the incidence or severity of IDH include optimization of the dialysis prescription (cool dialysate, UFR, sodium profiling and high-flux haemofiltration), interventions during the dialysis session (midodrine, mannitol, food intake, intradialytic exercise and intermittent pneumatic compression of the lower limbs) and interventions in the interdialysis period (lower interdialytic weight gain and blood pressure–lowering drugs). However, the evidence base for many of these interventions is thin and optimal prevention and management of IDH awaits further clinical investigation. Developing a consensus definition of IDH will facilitate clinical research. We review the most recent findings on risk factors, pathophysiology and management of IDH and, based on this, we call for a new consensus definition of IDH based on clinical outcomes and define a roadmap for IDH research.

Integrated strategies to prevent intradialytic hypotension: research protocol of the DialHypot study, a prospective randomised clinical trial in hypotension-prone haemodialysis patients

INTRODUCTION

In patients on maintenance haemodialysis (HD), intradialytic hypotension (IDH) is a clinical problem that nephrologists and dialysis nurses face daily in their clinical routine. Despite the technological advances in the field of HD, the incidence of hypotensive events occurring during a standard dialytic treatment is still very high. Frequently recurring hypotensive episodes during HD sessions expose patients not only to severe immediate complications but also to a higher mortality risk in the medium term. Various strategies aimed at preventing IDH are currently available, but there is lack of conclusive data on more integrated approaches combining different interventions.

METHODS AND ANALYSIS

This is a prospective, randomised, open-label, crossover trial (each subject will be used as his/her own control) that will be performed in two distinct phases, each of which is divided into several subphases. In the first phase, 27 HD sessions for each patient will be used, and will be aimed at the validation of a new ultrafiltration (UF) profile, designed with an ascending/descending shape, and a standard dialysate sodium concentration. In the second phase, 33 HD sessions for each patient will be used and will be aimed at evaluating the combination of different UF and sodium profiling strategies through individualised dialysate sodium concentration.

ETHICS AND DISSEMINATION

The trial protocol has been reviewed and approved by the local Institutional Ethics Committee (Comitato Etico AVEN, prot. 43391 22.10.19). The results of the trial will be presented at local and international conferences and submitted for publication to a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT03949088).

Blood pressure and volume management in dialysis: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

Blood pressure (BP) and volume control are critical components of dialysis care and have substantial impacts on patient symptoms, quality of life, and cardiovascular complications. Yet, developing consensus best practices for BP and volume control have been challenging, given the absence of objective measures of extracellular volume status and the lack of high-quality evidence for many therapeutic interventions. In February of 2019, Kidney Disease: Improving Global Outcomes (KDIGO) held a Controversies Conference titled Blood Pressure and Volume Management in Dialysis to assess the current state of knowledge related to BP and volume management and identify opportunities to improve clinical and patient-reported outcomes among individuals receiving maintenance dialysis. Four major topics were addressed: BP measurement, BP targets, and pharmacologic management of suboptimal BP; dialysis prescriptions as they relate to BP and volume; extracellular volume assessment and management with a focus on technology-based solutions; and volume-related patient symptoms and experiences. The overarching theme resulting from presentations and discussions was that managing BP and volume in dialysis involves weighing multiple clinical factors and risk considerations as well as patient lifestyle and preferences, all within a narrow therapeutic window for avoiding acute or chronic volume-related complications. Striking this challenging balance requires individualizing the dialysis prescription by incorporating comorbid health conditions, treatment hemodynamic patterns, clinical judgment, and patient preferences into decision-making, all within local resource constraints.

Is high-volume post-dilution haemodiafiltration associated with risk of fluid volume imbalance? A national multicentre cross-sectional cohort study

Background

Fluid overload is frequent among hemodialysis (HD) patients. Dialysis therapy itself may favor sodium imbalance from sodium dialysate prescription. As on-line hemodiafiltration (OL-HDF) requires large amounts of dialysate infusion, this technique can expose to fluid accumulation in case of a positive sodium gradient between dialysate and plasma. To evaluate this risk, we have analyzed and compared the fluid status of patients treated with HD or OL-HDF in French NephroCare centers.

Method

This is a cross-sectional and retrospective analysis of prevalent dialysis patients. Data were extracted from the EUCLID5 data base. Patients were split in 2 groups (HD and OL-HDF) and compared as whole group or matched patients for fluid status criteria including predialysis relative fluid overload (RelFO%) status from the BCM^®.

Results

2242 patients (age 71 years; female: 39%; vintage: 38 months; Charlson index: 6) were studied. 58% of the cohort were prescribed post-dilution OL-HDF. Comparing the HD and OL-HDF groups, there was no difference between HD and OL-HDF patients regarding the predialysis systolic BP, the interdialytic weight gain, the dialysate-plasma sodium gradient, and the predialysis RelFO%. The stepwise logistic regression did not find dialysis modality (HD or OL-HDF) associated with fluid overload or high predialysis systolic blood pressure. In OL-HDF patients, monthly average convective or weekly infusion volumes per session were not related with the presence of fluid overload.

Conclusions

In this cross-sectional study we did not find association between the use of post-dilution OL-HDF and markers of fluid volume excess. Aligned dialysis fluid sodium concentrations to patient predialysis plasma sodium and regular monitoring of fluid volume status by bioimpedance spectroscopy may have been helpful to manage adequately the fluid status in both OL-HDF and HD patients.

Uncertainties in BP management in dialysis patients

Hypertension in dialysis patients is extremely common. In this article, we review the current evidence for blood pressure (BP) goals in hemodialysis patients, and consider the effectiveness of interventions by which BP may be lowered, including manipulation of dietary and dialysate sodium; optimization of extracellular water; prolongation of dialysis time; and antihypertensive medication. Although two meta-analyses suggest lowering BP using antihypertensive drugs might be beneficial in reducing cardiovascular events and mortality, there are insufficient rigorously designed trials in hypertensive hemodialysis populations to determine preferred antihypertensive drug classes. We suggest aiming for predialysis systolic BP between 130 and 159 mm Hg, while at the same time acknowledge the significant limitations of the data upon which it is based. We conclude by summarizing current knowledge as regards management of hypertension in the peritoneal dialysis population and make recommendations for future research in this field.

Blood pressure targets and pharmacotherapy for hypertensive patients on hemodialysis

INTRODUCTION

Hypertension is highly prevalent in patients with end-stage kidney disease on hemodialysis and is often not well controlled. Blood pressure (BP) levels before and after hemodialysis have a U-shaped relationship with cardiovascular and all-cause mortality. Although antihypertensive drugs are recommended for patients in whom BP cannot be controlled appropriately by non-pharmacological interventions, large-scale randomized controlled clinical trials are lacking.

AREAS COVERED

The authors review the pharmacotherapy used in hypertensive patients on dialysis, primarily focusing on reports published since 2000. An electronic search of MEDLINE was conducted using relevant key search terms, including 'hypertension', 'pharmacotherapy', 'dialysis', 'kidney disease', and 'antihypertensive drug'. Systematic and narrative reviews and original investigations were retrieved in our research.

EXPERT OPINION

When a drug is administered to patients on dialysis, the comorbidities and characteristics of each drug, including its dialyzability, should be considered. Pharmacological lowering of BP in hypertensive patients on hemodialysis is associated with improvements in mortality. β-blockers should be considered first-line agents and calcium channel blockers as second-line therapy. Renin-angiotensin-aldosterone system inhibitors have not shown superiority to other antihypertensive drugs for patients on hemodialysis.

Thirst in patients on chronic hemodialysis: What do we know so far?

Thirst has been defined as "the sensation that leads animal's and human's actions toward the goal of finding and drinking water" or as "any drive that can motivate water intake, regardless of cause". Thirst, together with xerostomia, is the main cause of poor adherence to fluid restriction and of excessive intake of fluids in patients on chronic hemodialysis, and consequently of high interdialytic weight gain. Interdialytic weight gain (IDWG) should be lower than 4.0-4.5% of dry weight. Unfortunately, many patients have an IDWG greater than this value and some have IDWG of 10-20%. High IDWG is associated with a higher risk of all-cause and cardiovascular death and increased morbidity, such as ventricular hypertrophy and major adverse cardiac and cerebrovascular events. In addition, high IDWG leads to supplementary weekly dialysis sessions with consequent deterioration of quality of life and increased costs. Thus, the knowledge of thirst in patients on chronic hemodialysis is essential to prompt its adequate management to limit IDWG in the routine clinical practice. The present review aims to describe the physiology of thirst in patients on chronic hemodialysis, as well as the prevalence, its measures, the associated variables, the consequences, and the strategies for its reduction.

Dietary Daily Sodium Intake Lower than 1500 mg Is Associated with Inadequately Low Intake of Calorie, Protein, Iron, Zinc and Vitamin B1 in Patients on Chronic Hemodialysis

Background: To measure daily sodium intake in patients on chronic hemodialysis and to compare the intake of nutrients, minerals, trace elements, and vitamins in patients who had a daily sodium intake below or above the value of 1500 mg recommended by the American Heart Association. Methods: Dietary intake was recorded for 3 days by means of 3-day diet diaries in prevalent patients on chronic hemodialysis. Each patient was instructed by a dietitian on how to fill the diary, which was subsequently signed by a next of kin. Results: We studied 127 patients. Mean sodium intake (mg) was 1295.9 ± 812.3. Eighty-seven (68.5%) patients had a daily sodium intake <1500 mg (group 1) and 40 (31.5%) ≥ 1500 mg (group 2). Correlation between daily sodium intake and daily calorie intake was significant (r = 0.474 [0.327 to 0.599]; p < 0.0001). Daily calorie intake (kcal/kg/day) was lower in group 1 (21.1 ± 6.6; p = 0.0001) than in group 2 (27.1 ± 10.4). Correlation between daily sodium intake and daily protein intake was significant (r = 0.530 [0.392 to 0.644]; p < 0.0001). The daily protein intake (grams/kg/day) was lower in group 1 (0.823 ± 0.275; p = 0.0003) than in group 2 (1.061 ± 0.419). Daily intake of magnesium, copper, iron, zinc, and selenium was significantly lower in group 1 than in group 2. Daily intake of vitamin A, B2, B3, and C did not differ significantly between group 1 and group 2. Daily intake of vitamin B1 was significantly lower in group 1 than in group 2. Significantly lower was, in group 1 than in group 2, the percentage of patients within the target value with regard to intake of calories (11.5% vs. 37.5%; p = 0.001) and proteins (9.2% vs. 27.5%; p = 0.015) as well as of iron (23% vs. 45%; p = 0.020), zinc (13.8% vs. 53.8%; p = 0.008) and vitamin B1 (8.1% vs. 50%; p < 0.001). Conclusion: A low daily intake of sodium is associated with an inadequately low intake of calorie, proteins, minerals, trace elements, and vitamin B1. Nutritional counselling aimed to reduce the intake of sodium in patients on chronic hemodialysis should not disregard an adequate intake of macro- and micronutrients, otherwise the risk of malnutrition is high.

Risk stratification for patients awaiting kidney transplantation: Role of bioimpedance derived edema index and nutrition status

BACKGROUND

Recent studies demonstrate that the edema index (ECW/TBW) may be a significant predictor of poor outcomes as a composite of overhydration and protein-energy wasting. There is no consensus regarding ECW/TBW cut-off values. We aimed to determine the performance of ECW/TBW in all-cause mortality prediction and to establish certain cut-off values in patients on chronic hemodialysis.

METHODS

Body composition of 158 hemodialysis patient was performed by using InBody S10 (Biospace, Seoul, Korea) analyzer. Demographic profile and laboratory data were collected. Subjective Global Assessment Scale (SGA) was used to assess nutrition status. In the mean follow up of 3.5 ± 1.15 years, two independent clinicians evaluated death cases and factors for all-cause mortality were established. Statistical analysis was performed with R software.

RESULTS

73 of 158 hemodialysis patients were on kidney transplant waiting list. Mean age of study subjects was 53.6 ± 15.1 years, 51.9% were females, and 13.9% had diabetes. During the follow-up period, 17.72% of patients died. They had significantly higher ECW/TBW values 0.393 vs 0.408, p < 0.001. Subjects with lower edema index had better nutrition according to SGA (SGA A 0.391; SGA B 0.400; SGA C 0.413; p < 0.001). The calculated ECW/TBW cut-off point for all-cause mortality was 0.4055, with sensitivity of 84.6%, specificity of 69.8%. On the other hand, the cut-off point for SGA scores B and C was 0.396 with sensitivity of 72.7% and specificity of 68.7%.

CONCLUSION

The manufacturer provided ECW/TBW cut-off point of 0.400 should be addressed carefully, because it varies depending on the selected outcome and population studied. InBody ECW/TBW reference values from 0.390 to 0.410 are the most promising in hemodialysis population to assess all-cause mortality, nutrition status and body composition.

Investigation of Acoustic Cardiographic Parameters before and after Hemodialysis

Patients with end-stage renal disease are at an increased risk of cardiovascular diseases and associated mortality. Acoustic cardiography is a technique in which cardiac acoustic data is synchronized with electric information to detect and characterize heart sounds and detect heart failure early. The aim of this study was to investigate acoustic cardiographic parameters before and after hemodialysis (HD) and their correlations with ankle-brachial index (ABI), brachial-ankle pulse wave velocity (baPWV), and ratio of brachial preejection period to ejection time (bPEP/bET) obtained from an ABI-form device in HD patients. This study enrolled 162 HD patients between October 2016 and April 2018. Demographic, medical, and laboratory data were collected. Acoustic cardiography was performed before and after HD to assess parameters including third heart sound (S3), fourth heart sound (S4), systolic dysfunction index (SDI), electromechanical activation time (EMAT), and left ventricular systolic time (LVST). The mean age of the enrolled patients was 60.4 ± 10.9 years, and 86 (53.1%) patients were male. S4 (p < 0.001) and LVST (p < 0.001) significantly decreased after HD, but EMAT (p < 0.001) increased. Multivariate forward linear regression analysis showed that EMAT/LVST before HD was negatively associated with albumin (unstandardized coefficient β = ‐0.076; p = 0.004) and ABI (unstandardized coefficient β = ‐0.115; p = 0.011) and positively associated with bPEP/bET (unstandardized coefficient β = 0.278; p = 0.003). Screening HD patients with acoustic cardiography may help to identify patients at a high risk of malnutrition, peripheral artery disease, and left ventricular systolic dysfunction.

Feasibility of Assessing Sodium-Associated Body Fluid Composition in End-Stage Renal Disease

BACKGROUND

Cardiovascular disease accounts for more than half of all deaths in the hemodialysis (HD) population. Although much of this mortality is associated with fluid overload (FO), FO is difficult to measure, and many HD patients have significant pulmonary congestion despite the absence of clinical presentation. Cohort studies have observed that FO, as measured by bioimpedance spectroscopy (BIS), correlates with mortality. Other studies have observed that lower sodium intake is associated with less fluid-related weight gain, improved hypertension, and survival. Whether sodium intake influences FO in HD patients as measured by BIS is not known.

OBJECTIVE

The aims of the study were to determine the feasibility of assessing the impact of sodium restriction on body fluid composition as measured by BIS among patients with three levels of sodium intake and to determine if there are statistical and/or clinical differences in BIS measures across sodium intake groups.

METHODS

We used a double-blinded randomized controlled trial design with three levels of sodium restriction, 2,400 mg per day, 1,500 mg per day, and unrestricted (control group), to test our aims. Forty-two HD patients from a tertiary acute care academic institution associated with three urban DaVita dialysis centers were enrolled. Participants remained in the inpatient center for 5 days and 4 nights and were randomly assigned to sodium intake groups. Body fluid composition was measured with BIS.

RESULTS

Recruitment, enrollment, and retention statistics supported the feasibility of the study design. Regression analyses showed that there were no statistically significant differences among sodium intake groups on any of the outcomes.

DISCUSSION

Our data suggest the need for additional research into the effects of sodium restriction on body fluid composition.

Registered dietitian nutritionists and perceptions of liberalizing the hemodialysis diet

BACKGROUND/OBJECTIVES

The objective of this study was to assess the level of awareness, comfort, and likelihood of liberalizing the hemodialysis diet in practicing renal registered dietitian nutritionists (RDN).

SUBJECTS/METHODS

An original, cross-sectional survey was sent to the Academy of Nutrition and Dietetics' Renal Practice Group in May 2017, consisting primarily of renal dietitians.

RESULTS

A total of 187 renal dietitians responded to the survey designed to assess their current practices regarding the renal diet for hemodialysis patients and how comfortable they would be liberalizing the current restrictions. On average, 16.3% of dietitians are extremely likely to liberalize the restrictions on various food groups including fruits and vegetables, beans and legumes, and whole grains.

CONCLUSIONS

RDN feel confident in their ability to interpret and apply evidence-based literature into practice, and they are moderately comfortable liberalizing the renal diet. The participants were generally more comfortable liberalizing the phosphorus restriction than the potassium restriction, and the sodium restriction remains important to control interdialytic weight gain and hypertension. Future research is needed to establish efficacy of a liberalized diet as well as interventions to help RDN feel more comfortable implementing a liberalization of the renal diet.

Impact of salt taste dysfunction on interdialytic weight gain for hemodialysis patients; a cross-sectional study

Background

Little is known about salt taste dysfunction among hemodialysis (HD) patients. This study aimed to elucidate the prevalence of salt taste dysfunction and its relationship with interdialytic weight gain (IDWG) among HD patients.

Methods

A single-center cross-sectional study involving 99 maintenance HD patients was conducted in September 2015. Salt taste threshold was measured using a salt-impregnated test strip. Salt taste dysfunction was defined as a recognition threshold of ≥0.8%. IDWG was calculated as the mean value of weight gain at the beginning of each week during a 1-month period before the taste test. We performed a multivariate analysis using the standard linear regression model to investigate the association between salt taste dysfunction and IDWG.

Results

Among the 99 participants, 42% had a recognition threshold of 0.6%, whereas 38% had a recognition threshold of ≥1.6%. Overall, the prevalence of salt taste dysfunction was 58%. The mean (±SD) IDWG was 4.9% (±1.7%), and there was no significant difference in IDWG between the two groups with (4.9%) and without (4.8%) salt taste dysfunction (P = 0.90). A multivariate analysis indicated that salt taste dysfunction is not significantly associated with IDWG (mean difference = 0.06; 95% confidence interval = − 0.27 to 0.40).

Conclusions

The prevalence of salt taste dysfunction was very high among HD patients who had a unique distribution of salt taste recognition thresholds with two peaks. We found no significant association between salt taste dysfunction and IDWG.

Antihypertensive Agents in the Dialysis Patient

PURPOSE OF REVIEW

Hypertension and antihypertensive drug utilization are remarkably prevalent in ESRD patients. Management of blood pressure elevation in this population is complicated by many factors, including a multidimensional etiology, challenges in obtaining accurate and appropriately timed blood pressure measurements, highly specific drug dosing requirements, and a paucity of outcomes-based evidence to guide management decisions. The purpose of this review is to summarize and apply knowledge from existing clinical trials to enhance safe and effective use of antihypertensive agents in dialysis patients.

RECENT FINDINGS

Two meta-analyses have established the benefit of antihypertensive therapy in ESRD. Data supporting the use of one antihypertensive class over another is less robust; however, beta-blockers have more clearly demonstrated improved cardiovascular outcomes in prospective randomized trials. Interdialytic home blood pressure monitoring has been demonstrated to be better associated with cardiovascular outcomes than clinic pre- or post-dialysis readings and should ideally be considered as a routine part of blood pressure management in this population. As data from small trials provides limited guidance for the management of hypertension in ESRD, more research is needed to guide medication selection and utilization. Specifically, large prospective randomized trails comparing cardiovascular outcomes of various medication classes and differing blood pressure targets are needed.

Interdialytic weight gain and vasculopathy in children on hemodialysis: a single center study

BACKGROUND

Increased interdialytic weight gain (IDWG) has been associated with poor outcomes in adults, but its impact on hemodialysis vasculopathy in children is unknown.

METHODS

Nineteen patients (age 9 to 19 years old) with a median hemodialysis duration of 10.4 months were enrolled. Cardiovascular evaluation included left ventricular mass index (LVMI), pulse wave velocity (PWV), and carotid intima-media thickness (cIMT) measurements. PWV and cIMT were expressed as z-scores based on reference values in healthy children. Blood pressure (BP) evaluation consisted in a 24-h ambulatory BP monitoring. Mean IDGW and residual urine output during the 6 months prior to cardiovascular examination were calculated.

RESULTS

Increased cIMT, LVMI, and PWV was observed in 11 (57.9%), 7 (36.8%), and 5 (26.3%) patients respectively, while BP was normal in all patients. Median IDWG was 3.5% (1.8-6.7). Residual urine output and BP status did not significantly differ between patients with IDWG ≥ or < 4%. After linear regression, IDWG was correlated to cIMT z-score (r² = 0.485, p = 0.001), but not to PWV z-score (r² = 0.04, p = 0.415) and LVMI (r² = 0.092, p = 0.206). After univariate logistic regression, IDWG ≥ 4% was significantly associated to increased cIMT (above 1.65 SDS) (odds ratio 12.25, 95% confidence interval 1.08-138.988). The trend toward an increased cIMT with IDWG ≥ 4% was observed in both patients with short and long dialysis vintage.

CONCLUSIONS

High IDWG is associated with increased cIMT in hemodialyzed children independently of BP control and dialysis vintage. This observation reinforces the importance of interventions to avoid IDWG in hemodialyzed children.

Hypertension in patients on dialysis: diagnosis, mechanisms, and management

Hypertension (blood pressure > 140/90 mm Hg) is very common in patients undergoing regular dialysis, with a prevalence of 70-80%, and only the minority has adequate blood pressure (BP) control. In contrast to the unclear association of predialytic BP recordings with cardiovascular mortality, prospective studies showed that interdialytic BP, recorded as home BP or by ambulatory blood pressure monitoring in hemodialysis patients, associates more closely with mortality and cardiovascular events. Although BP is measured frequently in the dialysis treatment environment, aspects related to the measurement technique traditionally employed may be unsatisfactory. Several other tools are now available and being used in clinical trials and in clinical practice to evaluate and treat elevated BP in chronic kidney disease (CKD) patients. While we wait for the ongoing review of the CKD Blood Pressure KIDGO guidelines, there is no guideline for the dialysis population addressing this important issue. Thus, the objective of this review is to provide a critical analysis of the information available on the epidemiology, pathogenic mechanisms, and the main pillars involved in the management of blood pressure in stage 5-D CKD, based on current knowledge.

Pharmacodynamics, Safety, and Tolerability of the NHE3 Inhibitor Tenapanor: Two Trials in Healthy Volunteers

Background

Tenapanor, a small molecule with minimal systemic availability, is a first-in-class sodium/hydrogen exchanger 3 (NHE3) inhibitor that acts in the gut. Here, we evaluate the pharmacodynamics and safety of tenapanor in healthy adults.

Methods

Two phase I, single-center, randomized, double-blind, placebo-controlled studies were performed. The first study assessed single-ascending oral tenapanor doses of 10, 50, 150, 450, and 900 mg (n = 8 per group; six tenapanor, two placebo) and multiple ascending doses over 7 days of 3, 10, 30, and 100 mg q.d. (n = 10 per group; eight tenapanor, two placebo). In the second study, different tenapanor regimens were evaluated over 7 days (n = 15 per group; 12 tenapanor, three placebo): 15 mg twice daily (b.i.d.), 30 mg once daily (q.d.), 30 mg b.i.d., 30 mg three times daily (t.i.d.), 60 mg b.i.d., escalating b.i.d. dose (daily total 30–90 mg), 30 mg b.i.d. with psyllium.

Results

Tenapanor produced generally dose-dependent increases in stool sodium excretion and decreases in urinary sodium excretion versus placebo; in addition, twice-daily dosing appeared to have a greater effect on sodium absorption than once-daily dosing with an equivalent daily dose. Tenapanor softened stool consistency and increased stool frequency and weight from baseline versus placebo. Tenapanor concentrations were below the quantification limit (0.5 ng/ml) in 98.5% of 895 plasma samples. Adverse events were mild or moderate in severity, and were typically gastrointestinal in nature. There were no clinically relevant changes in serum electrolytes.

Conclusions

Tenapanor was well tolerated and resulted in reduced intestinal sodium absorption and softer stool consistency versus placebo. Systemic exposure to tenapanor was minimal. These results support potential use of tenapanor in patients who could benefit from modification of gastrointestinal sodium balance.

ClinicalTrials.gov identifiers

NCT02819687, NCT02796131.

Electronic supplementary material

The online version of this article (10.1007/s40261-017-0614-0) contains supplementary material, which is available to authorized users.

Hypertension in Pediatric Dialysis Patients: Etiology, Evaluation, and Management

PURPOSE OF REVIEW

Review epidemiology, pathophysiology, and management of hypertension in the pediatric dialysis population.

RECENT FINDINGS

Interdialytic blood pressure measurement, especially with ambulatory blood pressure monitoring, is the gold standard to assess for hypertension. Tools to assess dry weight aid in achievement of euvolemia, the primary therapy for management of hypertension. Persistent hypertension should be treated with antihypertensive medications and potentially with native nephrectomies. Cardiovascular disease continues to be the primary cause of morbidity and mortality in the dialysis population with hypertension as an important modifiable factor. Achievement on dry weight and limiting both aggressiveness of interdialytic weight gain and ultrafiltration rate underlie the best approach. Tools to assess volume status beyond clinical assessment have shown promise in achieving euvolemia. When hypertension persists despite achievement of euvolemia, antihypertensive medications may be required and in some cases native nephrectomies. Future studies in children are needed to determine the best antihypertensive class and ideal rate of ultrafiltration on hemodialysis towards achievement of normotension and reduction of cardiovascular risk.

Dietary Sodium and Other Nutrient Intakes among Patients Undergoing Hemodialysis in New Zealand

This study describes baseline intakes of sodium and other nutrients in a multi-ethnic sample of hemodialysis patients in New Zealand participating in the SoLID Trial between May/2013 to May/2016. Baseline 3-day weighed food record collections were analyzed using Foodworks 8 Professional food composition database, supplemented by other sources of nutrient information. Intakes of dietary sodium and other nutrients were compared with relevant guidelines and clinical recommendations. Eighty-five participants completed a 3-day weighed food record. The mean (SD) sodium intake was 2502 (957) mg/day at and more than half of the participants exceeded recommended intake levels. Sodium intake was positively associated with energy intake. Only 5% of participants met the recommended calorie density; nine percent of participants ate the recommended minimum of 1.2 g/kg of protein per day; 68% of participants were consuming inadequate fiber at baseline. A high proportion of dialysis patients in SoLID Trial did not meet current renal-specific dietary recommendations. The data show excess sodium intake. It is also evident that there was poor adherence to dietary guidelines for a range of other nutrients. A total diet approach is needed to lower sodium intake and improve total diet quality among hemodialysis patients in New Zealand.

Impact of salt reduction in meals consumed during hemodialysis sessions on interdialytic weight gain and hemodynamic stability

INTRODUCTION

Patients on hemodialysis (HD) are advised to limit daily water- and salt intake to reduce interdialytic weight gain (IDWG). To counterbalance protein-losses, protein-rich meals are sometimes provided during HD sessions, but their salt content is not always taken into account. The aim of this study was to assess the influence of a lower salt content of meals provided during HD sessions on IDWG, blood pressure (BP), and hemodynamic stability during dialysis.

METHODS

This monocentric, interventional study was proposed to all the patients treated with three weekly HD sessions. The first two months of the study (high salt period), the patients continued to receive one sandwich containing 2.4 g of salt per session. Then, we reduced its salt content from 2.4 to 1.4 g, and patients received this "low-salt sandwich" at each dialysis session for four months. The mean values of IDWG, BP, and dry weight of the first two months were compared with those collected during the low salt periods (2-6 months).

FINDINGS

Forty out of 76 patients who initially agreed to participate were free of hospitalization, transplantation, and transfer to another center or death during the study period and were included in the final analysis (35% women). Median age was 63 years (range 28-90), 22.5% had a residual diuresis > 0.5 L/day. IDWG baseline decreased from 2.17 ± 0.98 to 2.03 ± 1 kg (P = 0.001) two months and to 2.09 ± 1.01 kg (P = 0.009) four months after we had lowered the salt content of the sandwich. The number of symptomatic intradialytic hypotension was also reduced (6.1% vs., respectively, 3.2% and 3.3% of HD sessions; P = 0.004).

DISCUSSION

IDWG was reduced and hemodynamic stability improved after the reduction of the salt content of perdialytic meals. This suggests that salt consumed during HD matters and might influence salt and water intake outside the dialysis unit.

Why does the choice of dialysate sodium concentration remain controversial?

The choice of the ideal dialysate sodium concentration remains controversial. Most dialysis centers have a standard dialysate concentration. In theory, choosing a dialysate sodium concentration lower than serum sodium should result in an additional loss of sodium by diffusion with a reduction in the prevalence of hypertension and interdialytic weight gains (IDWGs) on one hand, but with potential increased risk of intradialytic hypotension and cramps on the other hand, and the opposite effects may accompany the choice of dialysate sodium concentrations greater than serum concentration. Although most studies have reported a reduction in IDWG with lower dialysate sodium concentrations, the effects on blood pressure control, and adverse intradialytic events have been variable. Different outcomes between studies may be partially explained by patient selection, with differences in dietary sodium intake, urinary sodium losses, and sodium stores in the body. In addition, multicenter trials potentially introduce additional confounders, including differences in local quality control of delivered dialysate sodium concentration and sodium measurements. Although there may be advantages for lower dialysate sodium concentration, observational studies have reported a survival advantage for higher dialysate sodium concentrations for those patients with lower serum sodium concentrations pre-dialysis. As there is no current consensus for a universal dialysate sodium concentration, attention has turned to considering an individualized approach to choosing a dialysate sodium concentration.

Blood pressure management in children on dialysis

Hypertension is a leading cause of cardiovascular complications in children on dialysis. Volume overload and activation of the renin-angiotensin-aldosterone system play a major role in the pathophysiology of hypertension. The first step in managing blood pressure (BP) is the careful assessment of ambulatory BP monitoring. Volume control is essential and should start with the accurate identification of dry weight, based on a comprehensive assessment, including bioimpedance analysis and intradialytic blood volume monitoring (BVM). Reduction of interdialytic weight gain (IDWG) is critical, as higher IDWG is associated with a worse left ventricular mass index and poorer BP control: it can be obtained by means of salt restriction, reduced fluid intake, and optimized sodium removal in dialysis. Optimization of peritoneal dialysis and intensified hemodialysis or hemodiafiltration have been shown to improve both fluid and sodium management, leading to better BP levels. Studies comparing different antihypertensive agents in children are lacking. The pharmacokinetic properties of each drug should be considered. At present, BP control remains suboptimal in many patients and efforts are needed to improve the long-term outcomes of children on dialysis.

Intradialytic hypotension

PURPOSE OF REVIEW

This review focuses on recent advances in our understanding of intradialytic hypotension (IDH) and measures that may reduce its frequency.

RECENT FINDINGS

The frequency and severity of IDH predict the risk for adverse clinical outcomes. The highest mortality risks associated with IDH were observed when the intradialytic systolic blood pressure (SBP) nadirs were <90 and <100 mmHg and the predialysis SBP were ≤159 mmHg or ≥160 mmHg, respectively. Interdialytic weight gain (IDWG) ≥3 kg occurs more frequently among patients with IDH. Prolonged and possibly more frequent dialysis, use of biofeedback devices, dialysate cooling and limiting sodium loading are useful measures to reduce the frequency of IDH.

SUMMARY

Frequent IDH is associated with high IDWGs and a poor prognosis. Studies on prolonged dialysis, biofeedback devices and cooled dialysate have yielded promising results. Intradialytic relative blood volume monitoring devices have been investigated in preventing IDH but results are mixed. Administration of a sodium/hydrogen exchange isoform 3 inhibitor increases stool sodium but has not been shown to decrease IDWG. IDH continues to be a significant dialysis complication deserving of further investigation.

Hypertension in dialysis patients: a consensus document by the European Renal and Cardiovascular Medicine (EURECA-m) working group of the European Renal Association - European Dialysis and Transplant Association (ERA-EDTA) and the Hypertension and the Kidney working group of the European Society of Hypertension (ESH)

In patients with end-stage renal disease treated with hemodialysis or peritoneal dialysis, hypertension is very common and often poorly controlled. Blood pressure (BP) recordings obtained before or after hemodialysis display a J-shaped or U-shaped association with cardiovascular events and survival, but this most likely reflects the low accuracy of these measurements and the peculiar hemodynamic setting related with dialysis treatment. Elevated BP by home or ambulatory BP monitoring is clearly associated with shorter survival. Sodium and volume excess is the prominent mechanism of hypertension in dialysis patients, but other pathways, such as arterial stiffness, activation of the renin-angiotensin-aldosterone and sympathetic nervous systems, endothelial dysfunction, sleep apnea and the use of erythropoietin-stimulating agents may also be involved. Nonpharmacologic interventions targeting sodium and volume excess are fundamental for hypertension control in this population. If BP remains elevated after appropriate treatment of sodium-volume excess, the use of antihypertensive agents is necessary. Drug treatment in the dialysis population should take into consideration the patient's comorbidities and specific characteristics of each agent, such as dialysability. This document is an overview of the diagnosis, epidemiology, pathogenesis and treatment of hypertension in patients on dialysis, aiming to offer the renal physician practical recommendations based on current knowledge and expert opinion and to highlight areas for future research.

Oxidative Stress in Hemodialysis Patients: A Review of the Literature

Hemodialysis (HD) patients are at high risk for all-cause mortality and cardiovascular events. In addition to traditional risk factors, excessive oxidative stress (OS) and chronic inflammation emerge as novel and major contributors to accelerated atherosclerosis and elevated mortality. OS is defined as the imbalance between antioxidant defense mechanisms and oxidant products, the latter overwhelming the former. OS appears in early stages of chronic kidney disease (CKD), advances along with worsening of renal failure, and is further exacerbated by the HD process per se. HD patients manifest excessive OS status due to retention of a plethora of toxins, subsidized under uremia, nutrition lacking antioxidants and turn-over of antioxidants, loss of antioxidants during renal replacement therapy, and leukocyte activation that leads to accumulation of oxidative products. Duration of dialysis therapy, iron infusion, anemia, presence of central venous catheter, and bioincompatible dialyzers are several factors triggering the development of OS. Antioxidant supplementation may take an overall protective role, even at early stages of CKD, to halt the deterioration of kidney function and antagonize systemic inflammation. Unfortunately, clinical studies have not yielded unequivocal positive outcomes when antioxidants have been administered to hemodialysis patients, likely due to their heterogeneous clinical conditions and underlying risk profile.

3 Tesla 23Na Magnetic Resonance Imaging During Acute Kidney Injury

RATIONALE AND OBJECTIVES

Sodium and proton magnetic resonance imaging (²³Na/¹H-MRI) have shown that muscle and skin can store Na⁺ without water. In chronic renal failure and in heart failure, Na⁺ mobilization occurs, but is variable depending on age, dialysis vintage, and other features. Na⁺ storage depots have not been studied in patients with acute kidney injury (AKI).

MATERIALS AND METHODS

We studied 7 patients with AKI (mean age: 51.7 years; range: 25-84) and 14 age-matched and gender-matched healthy controls. All underwent ²³Na/¹H-MRI at the calf. Patients were studied before and after acute hemodialysis therapy within 5-6 days. The ²³Na-MRI produced grayscale images containing Na⁺ phantoms, which served to quantify Na⁺ contents. A fat-suppressed inversion recovery sequence was used to quantify H₂O content.

RESULTS

Plasma Na⁺ levels did not change. Mean Na⁺ contents in muscle and skin did not significantly change following four to five cycles of hemodialysis treatment (before therapy: 32.7 ± 6.9 and 44.2 ± 13.5 mmol/L, respectively; after dialysis: 31.7 ± 10.2 and 42.8 ± 11.8 mmol/L, respectively; P > .05). Water content measurements did not differ significantly before and after hemodialysis in muscle and skin (P > .05). Na⁺ contents in calf muscle and skin of patients before hemodialysis were significantly higher than in healthy subjects (16.6 ± 2.1 and 17.9 ± 3.2) and remained significantly elevated after hemodialysis.

CONCLUSIONS

Na⁺ in muscle and skin accumulates in patients with AKI and, in contrast to patients receiving chronic hemodialysis and those with acute heart failure, is not mobilized with hemodialysis within 5-6 days.

A brief review of intradialytic hypotension with a focus on survival

Intradialytic hypotension (IDH), a common complication of ultrafiltration during hemodialysis therapy, is associated with high mortality and morbidity. IDH, defined as a nadir systolic blood pressure of less than 90 mm Hg on more than 30% of treatments, is a relevant definition and is correlated with mortality. Risk factors for IDH include patient demographics, anti-hypertensive medication use, larger interdialytic weight gain, and dialysis prescription features as dialysate sodium, high ultrafiltration rate, and dialysate temperature. A high frequency of IDH events carries a substantial death risk. An ultrafiltration rate >10 mL/h/kg, and even more so >13 mL/h/kg, is highly predictive of cardiovascular and all-cause mortality. Evidence suggests that IDH causes acute reversible segmental myocardial hypoperfusion and contractile dysfunction (myocardial stunning), which can result in long-term loss of myocardial contractility, leading to premature death. IDH also has negative end-organ effects on the brain and gut, contributing to mortality through stroke, and endotoxin translocation with associated inflammation and protein-energy wasting. Given strong association of IDH and dialysis mortality, a paradigm shift to its approach is urgently needed. Randomized controlled trials are required to prospectively test drugs and monitoring devices which may reduce IDH.

Interplay of volume, blood pressure, organ ischemia, residual renal function, and diet: certainties and uncertainties with dialytic management

Extracellular fluid volume overload and its inevitable consequence, hypertension, increases cardiovascular mortality in the long term by leading to left ventricular hypertrophy, heart failure, and ischemic heart disease in dialysis patients. Unlike antihypertensive medications, a strict volume control strategy provides optimal blood pressure control without need for antihypertensive drugs. However, utilization of this strategy has remained limited because of several factors, including the absence of a gold standard method to assess volume status, difficulties in reducing extracellular fluid volume, and safety concerns associated with reduction of extracellular volume. These include intradialytic hypotension; ischemia of heart, brain, and gut; loss of residual renal function; and vascular access thrombosis. Comprehensibly, physicians are hesitant to follow strict volume control policy because of these safety concerns. Current data, however, suggest that a high ultrafiltration rate rather than the reduction in excess volume is related to these complications. Restriction of dietary salt intake, increased frequency, and/or duration of hemodialysis sessions or addition of temporary extra sessions during the process of gradually reducing postdialysis body weight in conventional hemodialysis and discontinuation of antihypertensive medications may prevent these complications. We believe that even if an unwanted effect occurs while gradually reaching euvolemia, this is likely to be counterbalanced by favorable cardiovascular outcomes such as regression of left ventricular hypertrophy, prevention of heart failure, and, ultimately, cardiovascular mortality as a result of the eventual achievement of normal extracellular fluid volume and blood pressure over the long term.

Target weight achievement and ultrafiltration rate thresholds: potential patient implications

BACKGROUND

Higher ultrafiltration (UF) rates and extracellular hypo- and hypervolemia are associated with adverse outcomes among maintenance hemodialysis patients. The Centers for Medicare and Medicaid Services recently considered UF rate and target weight achievement measures for ESRD Quality Incentive Program inclusion. The dual measures were intended to promote balance between too aggressive and too conservative fluid removal. The National Quality Forum endorsed the UF rate measure but not the target weight measure. We examined the proposed target weight measure and quantified weight gains if UF rate thresholds were applied without treatment time (TT) extension or interdialytic weight gain (IDWG) reduction.

METHODS

Data were taken from the 2012 database of a large dialysis organization. Analyses considered 152,196 United States hemodialysis patients. We described monthly patient and dialysis facility target weight achievement patterns and examined differences in patient characteristics across target weight achievement status and differences in facilities across target weight measure scores. We computed the cumulative, theoretical 1-month fluid-related weight gain that would occur if UF rates were capped at 13 mL/h/kg without concurrent TT extension or IDWG reduction.

RESULTS

Target weight achievement patterns were stable over the year. Patients who did not achieve target weight (post-dialysis weight ≥ 1 kg above or below target weight) tended to be younger, black and dialyze via catheter, and had shorter dialysis vintage, greater body weight, higher UF rate and more missed treatments compared with patients who achieved target weight. Facilities had, on average, 27.1 ± 9.7% of patients with average post-dialysis weight ≥ 1 kg above or below the prescribed target weight. In adjusted analyses, facilities located in the midwest and south and facilities with higher proportions of black and Hispanic patients and higher proportions of patients with shorter TTs were more likely to have unfavorable facility target weight measure scores. Without TT extension or IDWG reduction, UF rate threshold (13 mL/h/kg) implementation led to an average theoretical 1-month, fluid-related weight gain of 1.4 ± 3.0 kg.

CONCLUSIONS

Target weight achievement patterns vary across clinical subgroups. Implementation of a maximum UF rate threshold without adequate attention to extracellular volume status may lead to fluid-related weight gain.

Blood Pressure of Maintenance Hemodialysis Patients in the Dalmatian Region of Croatia: Differences between Hospital and Out-of-Hospital Dialysis Centers

AIMS

This study was aimed at comparing the incidence of arterial hypertension and blood pressure (BP) variance in hospital and out-of-hospital hemodialysis (HD) patients during HD sessions.

METHODS

A cross-sectional study was conducted for 1 week at all the HD centers in Dalmatia, Croatia. The pre-, intra-, and post-dialysis BP values were collected for 3 consecutive HD sessions per patient.

RESULTS

Of the 399 subjects, 73.9% were hypertensives, who showed higher interdialytic weight gain compared to the normotensives (2.58 vs. 2.40). Hospital and out-of-hospital HD patients received identical antihypertensive therapies, except that beta blockers were more frequently administered to out-of-hospital HD patients. Higher pre-, intra-, and post-dialysis BP values were recorded in patients at out-of-hospital HD centers.

CONCLUSION

The differences in BP variability and antihypertensive therapies administered to hospital HD patients as compared to out-of-hospital HD patients may reflect differing approaches by the nephrologists at these centers.

A phase 1 study of the safety, tolerability, pharmacodynamics, and pharmacokinetics of tenapanor in healthy Japanese volunteers

BACKGROUND

Tenapanor (RDX5791, AZD1722), a small molecule with minimal systemic availability, is an inhibitor of the sodium/hydrogen exchanger isoform 3 (NHE3). Tenapanor acts locally in the gut to reduce absorption of sodium and phosphate. It is being developed for the treatment of patients with hyperphosphatemia in CKD requiring dialysis and patients with constipation-predominant irritable bowel syndrome. We report the safety, pharmacodynamics, and pharmacokinetics of tenapanor in Japanese volunteers.

METHODS

In this phase 1, double-blind study (NCT02176252), healthy Japanese adults (aged 20-45 years) received single-dose tenapanor 180 mg (n = 6), repeated-dose tenapanor 15, 30, 60, or 90 mg twice daily (n = 12 each) for 7 days, or placebo (n = 14). All participants received a standardized diet.

RESULTS

Single and repeated doses of tenapanor resulted in higher mean stool sodium content vs. placebo (single dose, 41.9 mmol/day; repeated dose, range of means 21.3-32.2 mmol/day; placebo, 4.1 mmol/day) accompanied by lower urinary sodium content (single dose, 110 mmol/day; repeated dose, 101-112 mmol/day; placebo, 143 mmol/day). Additionally, stool phosphorus content was increased (single dose, 31.0 mmol/day; repeated dose, 17.6-24.8 mmol/day; placebo, 16.8 mmol/day) and urinary phosphorus content decreased (single dose, 18.7 mmol/day; repeated dose, 15.3-19.4 mmol/day; placebo, 25.5 mmol/day). Tenapanor had minimal systemic exposure, provided a softer stool consistency, and was well tolerated.

CONCLUSIONS

Tenapanor treatment reduced absorption of intestinal sodium and phosphate from the gut in Japanese adults. Tenapanor had minimal systemic exposure and was well tolerated. Further research into the clinical benefits of tenapanor is warranted.