Dialysate Sodium: Rationale for Evolution over Time

Association of Changes in Vector Length with Changes in Left Ventricular Mass among Patients on Maintenance Hemodialysis: A Secondary Analysis of the Frequent Hemodialysis Network Daily Trial

Key Points

Bioimpedance has been proposed as an objective method to assess volume status among patients receiving maintenance hemodialysis. The Frequent Hemodialysis Network Daily Trial measured bioimpedance parameters of volume status (vector length) and cardiac magnetic resonance imaging at baseline and 12 months. We observed that changes in vector length were inversely associated with changes in left ventricular mass and volume over a 12-month period.

Background

Hypervolemia is thought to be a major contributor to higher left ventricular mass (LVM), a potent predictor for cardiovascular mortality among patients on maintenance hemodialysis. We hypothesized that a decrease in vector length (a bioimpedance proxy of hypervolemia) would be associated with an increase in LVM.

Methods

Using data from the Frequent Hemodialysis Network Daily Trial (n =160), we used linear regression to assess the association of changes in vector length from baseline to month 12 with changes in magnetic resonance imaging measures of LVM and other cardiac parameters. We adjusted models for the randomized group, baseline vector length, age, sex, race, body mass index, vascular access, dialysis vintage, history of hypertension, heart failure, and diabetes, residual kidney function, predialysis systolic BP, ultrafiltration rate, serum-dialysate sodium gradient, hemoglobin, phosphate, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker use, erythropoietin dose, and equilibrated Kt/V.

Results

The mean age of the patients was 50±13 years; 35% were female. In the fully adjusted models, a decline in vector length (per 50 Ω/m; i.e ., increase in volume) was associated with a 6.8 g (95% confidence interval [CI], −0.1 to 13.7) and 2.6 g/m2 (95% CI, −1.2 to 6.3) increase in LVM and LVM index, respectively, and an increase of 15.0 ml (95% CI, 7.5 to 22.4), 7.3 ml (95% CI, 3.0 to 12.7), 7.8 ml (95% CI, 3.0 to 12.7), and −0.9% (95% CI, −3.1 to 1.3) in left ventricular end-diastolic volume, left ventricular end-systolic volume, left ventricular stroke volume, and left ventricular ejection fraction, respectively. The lowest tertile of change in vector length (i.e ., greater increase in volume) was associated with greater increases in left ventricular end-diastolic volume and left ventricular stroke volume, versus the highest tertile. There was no evidence of heterogeneity by randomized group.

Conclusions

Change in vector length, a bioimpedance-derived proxy of volume status, was inversely associated with indices of LVM and volume measured by cardiac magnetic resonance imaging in patients randomized to conventional or frequent hemodialysis over 12 months.

Effect of Dialysate and Plasma Sodium on Mortality in a Global Historical Hemodialysis Cohort

SIGNIFICANCE STATEMENT

This large observational cohort study aimed to investigate the relationship between dialysate and plasma sodium concentrations and mortality among maintenance hemodialysis patients. Using a large multinational cohort of 68,196 patients, we found that lower dialysate sodium concentrations (≤138 mmol/L) were independently associated with higher mortality compared with higher dialysate sodium concentrations (>138 mmol/L). The risk of death was lower among patients exposed to higher dialysate sodium concentrations, regardless of plasma sodium levels. These results challenge the prevailing assumption that lower dialysate sodium concentrations improve outcomes in hemodialysis patients. The study confirms that until robust evidence from randomized trials that are underway is available, nephrologists should remain cautious in reconsideration of dialysate sodium prescribing practices to optimize cardiovascular outcomes and reduce mortality in this population.

BACKGROUND

Excess mortality in hemodialysis (HD) patients is largely due to cardiovascular disease and is associated with abnormal fluid status and plasma sodium concentrations. Ultrafiltration facilitates the removal of fluid and sodium, whereas diffusive exchange of sodium plays a pivotal role in sodium removal and tonicity adjustment. Lower dialysate sodium may increase sodium removal at the expense of hypotonicity, reduced blood volume refilling, and intradialytic hypotension risk. Higher dialysate sodium preserves blood volume and hemodynamic stability but reduces sodium removal. In this retrospective cohort, we aimed to assess whether prescribing a dialysate sodium ≤138 mmol/L has an effect on survival outcomes compared with dialysate sodium >138 mmol/L after adjusting for plasma sodium concentration.

METHODS

The study population included incident HD patients from 875 Fresenius Medical Care Nephrocare clinics in 25 countries between 2010 and 2019. Baseline dialysate sodium (≤138 or >138 mmol/L) and plasma sodium (<135, 135-142, >142 mmol/L) concentrations defined exposure status. We used multivariable Cox regression model stratified by country to model the association between time-varying dialysate and plasma sodium exposure and all-cause mortality, adjusted for demographic and treatment variables, including bioimpedance measures of fluid status.

RESULTS

In 2,123,957 patient-months from 68,196 incident HD patients with on average three HD sessions per week dialysate sodium of 138 mmol/L was prescribed in 63.2%, 139 mmol/L in 15.8%, 140 mmol/L in 20.7%, and other concentrations in 0.4% of patients. Most clinical centers (78.6%) used a standardized concentration. During a median follow-up of 40 months, one third of patients ( n =21,644) died. Dialysate sodium ≤138 mmol/L was associated with higher mortality (multivariate hazard ratio for the total population (1.57, 95% confidence interval, 1.25 to 1.98), adjusted for plasma sodium concentrations and other confounding variables. Subgroup analysis did not show any evidence of effect modification by plasma sodium concentrations or other patient-specific variables.

CONCLUSIONS

These observational findings stress the need for randomized evidence to reliably define optimal standard dialysate sodium prescribing practices.

Personalizing electrolytes in the dialysis prescription: what, why and how?

Maintenance hemodialysis patients suffer from multiple comorbidities and treatment-related complications. A personalized approach to hemodialysis prescription could reduce some of these burdens by preventing complications such as excessive changes in blood pressure, arrhythmias, post-dialysis fatigue and decreased quality of life. A patient-centered approach to dialysate electrolyte concentrations represents one such opportunity. In addition to modifications in dialysate electrolyte concentrations, consideration of individual factors such as patients' serum concentrations, medication profiles, nutritional status and comorbidities is critical to tailoring hemodialysis prescriptions to optimize patient outcomes. The development of personalized dialysis treatment depends on the collection of comprehensive patient data, advances in technology, resource allocation and patient involvement in decision-making. This review discusses how the treatment of maintenance hemodialysis patients could benefit from individualized changes in certain dialysis fluid components.

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.

Management of Cardiovascular Diseases in Chronic Hemodialysis Patients

Hemodialysis (HD) is the main treatment modality for patients with end-stage kidney disease. Cardiovascular diseases (CVD) are highly prevalent in HD patients and are the leading cause of death in this population, with the mortality from CVD approximately 20 times higher than that of the general population. Traditional and non-traditional cardiovascular risk factors accelerate progression of CVD and exacerbate the prognosis in HD patients. This review provides a brief overview of the characteristics of CVD in HD patients, and a description of advances in its management.

Changes of Hemodynamic Parameters after Intradialytic Glucose Injection

BACKGROUND

Intradialytic hypotension (IDH) is a frequent complication of hemodialysis (HD). Current methods of IDH prevention are insufficient.

METHODS

We analyzed the intradialytic time course of systolic (SBP), diastolic (DBP), mean arterial (MAP), pulse pressure (PP), and heart rate (HR) in a group of chronic kidney disease (CKD) patients. First, 30 min into HD, a 40% glucose solution was injected into the venous line of the extracorporeal circulation at a dose of 0.5 g/kg of dry weight. Pressures and HR were measured in frequent intervals. Relative volume overload was determined by bioimpedance spectroscopy.

RESULTS

Thirty-five participants were studied. SBP increased after 5, 10, and 20 min of glucose infusion. DBP increased after 2 and 3 h and also at the end of HD. PP increased after 5, 10, and 20 min of glucose infusion and fell after the 2nd and 3rd hour and also at the end of HD. MAP increased after 2 and 3 h of glucose injection and at the end of HD. Significant interactions of the time course of SBP, DBP, MAP, with HR at baseline and of the time course of PP with fluid overload were observed. Symptomatic hypotensive episodes were absent.

CONCLUSIONS

Glucose infusions during HD prevent symptomatic IDH and do not cause severe hypertensive episodes.

Automated adjustment of dialysate sodium by the hemodialysis monitor: Rationale, implementation, and clinical benefits

Prescribing dialysate sodium is the responsibility of the physician, but there are currently no clear guidelines for this prescription. Furthermore, there is quite frequently a significant difference between prescribed and measured dialysate sodium. Several arguments, both theoretical and experimental, suggest that dialysate sodium should be adjusted individually in such a way as to result in a decreasing sodium profile that takes into account the patient's predialytic natremia. The generalization in clinical routine of this strategy requires the integration into the hemodialysis monitor of software making the machine capable to automatically adjust the dialysate sodium at each session. The only three such softwares that have been integrated into hemodialysis machines for routine clinical use are discussed. All three work with conductivity measurements as a surrogate for sodium concentrations. Although there are only a few publications on the use of these softwares in clinical practice, they appear to result in improved intradialytic tolerance to the dialysis treatment, better control of hypertension, and reduced thirst, leading to decreased interdialytic weight gain.

Fluid Overload and Tissue Sodium Accumulation as Main Drivers of Protein Energy Malnutrition in Dialysis Patients

Protein energy malnutrition is recognized as a leading cause of morbidity and mortality in dialysis patients. Protein-energy-wasting process is observed in about 45% of the dialysis population using common biomarkers worldwide. Although several factors are implicated in protein energy wasting, inflammation and oxidative stress mechanisms play a central role in this pathogenic process. In this in-depth review, we analyzed the implication of sodium and water accumulation, as well as the role of fluid overload and fluid management, as major contributors to protein-energy-wasting process. Fluid overload and fluid depletion mimic a tide up and down phenomenon that contributes to inducing hypercatabolism and stimulates oxidation phosphorylation mechanisms at the cellular level in particular muscles. This endogenous metabolic water production may contribute to hyponatremia. In addition, salt tissue accumulation likely contributes to hypercatabolic state through locally inflammatory and immune-mediated mechanisms but also contributes to the perturbation of hormone receptors (i.e., insulin or growth hormone resistance). It is time to act more precisely on sodium and fluid imbalance to mitigate both nutritional and cardiovascular risks. Personalized management of sodium and fluid, using available tools including sodium management tool, has the potential to more adequately restore sodium and water homeostasis and to improve nutritional status and outcomes of dialysis patients.

A first proof-of-concept for the non-invasive, time-efficient measurement of the plasma sodium concentration for individualized dialysis

Dialysis-induced changes in plasma sodium concentration may cause undesirable side effects. To prevent these, the sodium content in dialysis fluid has to be individualized based on the patient's plasma sodium concentration. In this paper, we describe a simple conductivity based method for measuring the plasma sodium concentration. The method is based on performing a bypass during which the residual volume on the dialysate side of the dialyzer at least partially adopts the sodium concentration on the blood side. The conductivity at dialysate outlet of the dialyzer after the end of bypass corresponds to the sodium concentration. We show that already 14 s of bypass are sufficient to subsequently measure a conductivity that correlates with the blood-side sodium concentration. Thus, the short bypass method allows a time saving of 88% compared to the long bypass of 120 s. In vitro experiments with bovine blood show that plasma sodium concentration can be non-invasively and time-efficiently measured during dialysis. Bland Altman analysis reveals a bias of 0.28 mmol/l and limits of agreement of -3.17 and 3.74 mmol/l for the long bypass. For the short bypass, bias is 0.09 mmol/l and limits are -3.90 and 4.08 mmol/l. Since the method presented is based on established conductivity cells, no additional sensors are required, so that the method could be easily implemented in dialysis machines. In future, performing a bypass at the beginning of a treatment may be used to adjust the composition of dialysis fluid individually for each patient.

A randomized controlled trial of two dialysate sodium concentrations in hospitalized hemodialysis patients

BACKGROUND

Several large dialysis organizations have lowered the dialysate sodium concentration (DNa) in an effort to ameliorate hypervolemia. The implications of lower DNa on intra-dialytic hypotension (IDH) during hospitalizations of hemodialysis (HD) patients is unclear.

METHODS

In this double-blind, single center, randomized controlled trial (RCT), hospitalized maintenance HD patients were randomized to receive higher (142 mmol/L) or lower (138 mmol/L) DNa for up to six sessions. Blood pressure (BP) was measured in a standardized fashion pre-HD, post-HD and every 15 min during HD. The endpoints were: (i) the average decline in systolic BP (pre-HD minus lowest intra-HD, primary endpoint) and (ii) the proportion of total sessions complicated by IDH (drop of ≥20 mmHg from the pre-HD systolic BP, secondary endpoint).

RESULTS

A total of 139 patients completed the trial, contributing 311 study visits. There were no significant differences in the average systolic blood pressure (SBP) decline between the higher and lower DNa groups (23 ± 16 versus 26 ± 16 mmHg; P = 0.57). The proportion of total sessions complicated by IDH was similar in the higher DNa group, compared with the lower DNa group [54% versus 59%; odds ratio 0.72; 95% confidence interval (95% CI) 0.36-1.44; P = 0.35]. In post hoc analyses adjusting for imbalances in baseline characteristics, higher DNa was associated with 8 mmHg (95% CI 2-13 mmHg) less decline in SBP, compared with lower DNa. Patient symptoms and adverse events were similar between the groups.

CONCLUSIONS

In this RCT for hospitalized maintenance of HD patients, we found no difference in the absolute SBP decline between those who received higher versus lower DNa in intention-to-treat analyses. Post hoc adjusted analyses suggested a lower risk of IDH with higher DNa; thus, larger, multi-center studies to confirm these findings are warranted.

Dialysate sodium management in hemodialysis and on-line hemodiafiltration: the single-pool kinetic model revisited

BACKGROUND

Determining the optimal dialysate sodium remains one of the challenges of hemodialysis prescription. Several arguments suggest that the dialysate sodium should be individually adjusted according to the patient's natremia. This strategy is greatly facilitated by using an algorithm. Only three such algorithms have been embedded in hemodialysis machines for the widespread generalization of this strategy in clinical routine: the Diacontrol (Hospal-Baxter Healthcare Corp., Deerfield, IL, USA), the HFR-Aequilibrium (Bellco-Medtronic, Dublin, Ireland) and the Na-control (Fresenius Medical Care, Bad-Homburg, Germany).

METHODS

Model the solute mass-transfer across the dialyzer membrane in online hemodiafiltration and adapt the Diacontrol algorithm based on a single-pool kinetic model of sodium balance for quantifying ionic balance and managing tonicity.

RESULTS

1) Substituting sodium measurements with conductivity measurements allows the control of tonicity which is a more physiological parameter than natremia. 2) Consideration of all ion exchanges as a whole and not just sodium exchange avoids some of the assumptions required by kinetic modeling of sodium balance. 3) Equations provided by the model are applicable to both hemodialysis and online hemodiafiltration. 4) The differences between this model used by Diacontrol and the models on which the other two software's (HFR-Aequilibrium and Na-control) are based are highlighted.

CONCLUSIONS

The single-pool kinetic model validated for the management of natremia in hemodialysis is also valid for the management of tonicity for both conventional hemodialysis and all online hemodiafiltration procedures.

Association between dialysate sodium concentration and interdialytic weight gain in patients undergoing twice weekly haemodialysis

Background

Chronic kidney disease is highly prevalent across the globe with more than 2 million people worldwide requiring renal replacement therapy. Interdialytic weight gain is the change in body weight between two sessions of haemodialysis. Higher interdialytic weight gain has been associated with an increase in mortality and adverse cardiovascular outcomes. It has long been questioned whether using a lower dialysate sodium concentration during dialysis would reduce the interdialytic weight gain and hence prevent these adverse outcomes.

Methods

This study was a single blinded cross-over study of patients undergoing twice weekly haemodialysis at the Aga Khan University Hospital, Nairobi and Parklands Kidney Centre. It was conducted over a twelve-week period and patients were divided into two groups: dialysate sodium concentration of 137 meq/l and 140 meq/l. These groups switched over after a six-week period without a washout period. Univariate analysis was conducted using Fisher’s exact test for categorical data and Mann Whitney test for continuous data.

Results

Forty-one patients were included in the analysis. The mean age was 61.37 years, and 73% were males. The mean duration for dialysis was 2.53 years. The interdialytic weight gain was not significantly different between the two groups (2.14 for the 137 meq/l group and 2.35 for the 140 meq/l group, p = 0.970). Mean blood pressures were as follows: pre-dialysis: DNa 137 meq/l: systolic 152.14 ± 19.99, diastolic 78.99 ± 12.20, DNa 140 meq/l: systolic 156.95 ± 26.45, diastolic 79.75 ± 11.25 (p = 0.379, 0.629 respectively). Post-dialysis: DNa 137 meq/l: systolic 147.29 ± 22.22, diastolic 77.85 ± 12.82 DNa 140 meq/l: systolic 151.48 ± 25.65, diastolic 79.66 ± 15.78 (p = 0.569, 0.621 respectively).

Conclusion

There was no significant difference in the interdialytic weight gain as well as pre dialysis and post dialysis systolic and diastolic blood pressures between the two groups. Therefore, using a lower dialysate sodium concentration does not appear useful in altering the interdialytic weight gain or blood pressure although further studies are warranted with a larger sample size, taking into account residual renal function and longer duration for impact on blood pressures.

Relationship between measured and prescribed dialysate sodium in haemodialysis: a systematic review and meta-analysis

Background

Dialysate sodium (DNa) prescription policy differs between haemodialysis (HD) units, and the optimal DNa remains uncertain. We sought to summarize the evidence on the agreement between prescribed and delivered DNa, and whether the relationship varied according to prescribed DNa.

Methods

We searched MEDLINE and PubMed from inception to 26 February 2020 for studies reporting measured and prescribed DNa. We analysed results reported in aggregate with random-effects meta-analysis. We analysed results reported by individual sample, using mixed-effects Bland–Altman analysis and linear regression. Pre-specified subgroup analyses included method of sodium measurement, dialysis machine manufacturer and proportioning method.

Results

Seven studies, representing 908 dialysate samples from 10 HD facilities (range 16–133 samples), were identified. All but one were single-centre studies. Studies were of low to moderate quality. Overall, there was no statistically significant difference between measured and prescribed DNa {mean difference = 0.73 mmol/L [95% confidence interval (CI) −1.12 to 2.58; P = 0.44]} but variability across studies was substantial (I2 = 99.3%). Among individually reported samples (n = 295), measured DNa was higher than prescribed DNa by 1.96 mmol/L (95% CI 0.23–3.69) and the 95% limits of agreement ranged from −3.97 to 7.88 mmol/L. Regression analysis confirmed a strong relationship between prescribed and measured DNa, with a slope close to 1:1 (β = 1.16, 95% CI 1.06–1.27; P &lt; 0.0001).

Conclusions

A limited number of studies suggest that, on average, prescribed and measured DNa are similar. However, between- and within-study differences were large. Further consideration of the precision of delivered DNa is required to inform rational prescribing.

Fragmentation of care as a barrier to optimal ESKD management

Caring for patients with end-stage kidney disease (ESKD) in the United States is challenging, due in part to the complex epidemiology of the disease's progression as well as the ways in which care is delivered. As CKD progresses toward ESKD, the number of comorbidities increases and care involves multiple healthcare providers from multiple subspecialties. This occurs in the context of a fragmented US healthcare delivery system that is traditionally siloed by provider specialty, organization, as well as systems of payment and administration. This article describes the role of care fragmentation in the delivery of optimal ESKD care and identifies research gaps in the evidence across the continuum of care. We then consider the impact of care fragmentation on ESKD care from the patient and health system perspectives and explore opportunities for system-level interventions aimed at improving care for patients with ESKD.

Transcapillary transport of water, small solutes and proteins during hemodialysis

The semipermeable capillary walls not only enable the removal of excess body water and solutes during hemodialysis (HD) but also provide an essential mechanism for maintaining cardiovascular homeostasis. Here, we investigated transcapillary transport processes on the whole-body level using the three-pore model of the capillary endothelium with large, small and ultrasmall pores. The transcapillary transport and cardiovascular response to a 4-h hemodialysis (HD) with 2 L ultrafiltration were analyzed by simulations in a virtual patient using the three-pore model of the capillary wall integrated in the whole-body compartmental model of the cardiovascular system with baroreflex mechanisms. The three-pore model revealed substantial changes during HD in the magnitude and direction of transcapillary water flows through small and ultrasmall pores and associated changes in the transcapillary convective transport of proteins and small solutes. The fraction of total capillary hydraulic conductivity attributed to ultrasmall pores was found to play an important role in the transcapillary water transport during HD thus influencing the cardiovascular response to HD. The presented model provides a novel computational framework for a detailed analysis of microvascular exchange during HD and as such may contribute to a better understanding of dialysis-induced changes in blood volume and blood pressure.

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.

Temporal changes in dialysate [Na+] prescription from 1996 to 2018 and their clinical significance as judged from a meta-regression of clinical trials

Over the last two decades, the clinical care of dialysis patients has refocused sharply on fluid volume control. Dialysate [Na⁺] is a key, albeit under-investigated, clinical tool for manipulation of fluid volume on dialysis. In the article, we firstly use data from the Dialysis Outcomes and Practice Patterns Study to document the global decrease in dialysate [Na⁺] that has occurred from 1996 to 2018, and demonstrate the virtual disappearance of [Na⁺] profiling from routine dialysis practice over the same period. Second, we used data from previously synthesized randomized clinical trial evidence combined with that of a more recently published trail to assess the clinical significance of these changes, estimating the effects of different levels of low dialysate [Na⁺] on key clinical outcomes. Our analyses suggest that current levels of dialysate [Na⁺] in some health jurisdictions are possibly causing harm to many patients, especially given that real world populations are significantly less robust and more vulnerable than clinical trial ones. To quote a recent editorial, "more evidence needed before lower dialysate sodium concentrations can be recommended." That evidence is coming, and no further changes should be made to default customary practice until it is available.

A Combination of Hemodialysis with Hemoperfusion Helped to Reduce the Cardiovascular-Related Mortality Rate after a 3-Year Follow-Up: A Pilot Study in Vietnam

AIMS

Moderate to severe hyperparathyroidism (parathyroid hormone [PTH] concentrations ≥600 pg/mL) may increase the risk of cardiovascular problems and bone disease. We assume that a combination of hemodialysis with hemoperfusion may reduce the cardiovascular-related mortality rate in maintenance hemodialysis.

SUBJECTS AND METHODS

From 625 maintenance hemodialysis patients, 93 people met with our inclusion criteria. Based on the level of serum PTH, the patients were divided into 2 groups: 46 patients who underwent a combination of hemodialysis and hemoperfusion (HD + HP group) for consecutive 3 years and 47 patients who used hemodialysis only (HD group).

RESULTS

During 3 years of follow-up, the ratio of mortality was 4.3% in the HD + HP group which was significantly lower than in the HD group (17%), p = 0.049. Based on Kaplan-Meier analysis of cardiovascular-related mortality, patients in the HD group (red line) exhibited a significantly higher death rate compared to the HD + HP group (violet line) (log-rank test, p = 0.049).

CONCLUSION

We demonstrated that a combination of hemodialysis and hemoperfusion for 3 years helped to reduce the cardiovascular-related mortality rate.

Hemodialysis treatment in patients with severe electrolyte disorders: Management of hyperkalemia and hyponatremia

Significant deviations of serum potassium and sodium levels are frequently observed in hospitalized patients and are both associated with increased all‐cause and cardiovascular mortality. The presence of acute or chronic renal failure facilitates the pathogenesis and complicates the clinical management. In the absence of reliable outcome data in the context of dialysis prescription, requirement of renal replacement therapy in patients with severe electrolyte disturbances constitutes a therapeutic challenge. Recommendations for intradialytic management are based on pathophysiologic reasoning and clinical observations only, and as such, heterogeneous and limited to expert opinion level. This article reviews current strategies for the management of severe hyperkalemia and hyponatremia in hemodialysis patients.

The difference between delivered and prescribed dialysate sodium in haemodialysis machines

Background

The choice of dialysate sodium (DNa) for haemodialysis (HD) patients remains controversial, with some studies reporting that a lower DNa improves blood pressure control and reduces intradialytic weight gain. Studies on DNa depend on the alignment of programmed to delivered DNa. We wished to determine whether there were differences between programmed and delivered DNa.

Methods

Dialysate samples were obtained from three dialysis machines: Fresenius 4008H (F4008H) and 5008S (F5008S) and B-Braun hemodiafiltration (HDF) Dialog+(BB). DNa was measured by indirect ion-selective electrode (ISE), flame photometry (FP) and ion chromatography (IC) at different DNa concentrations.

Results

We tested 18 F5008S, 18 F4008H and 31 BB machines over 153 HD treatments. The median measured minus programmed DNa was significantly greater with the BB machine [ISE, 7 (6–8); FP, 7 (6–8); IC, 6 (5–7)], followed by the F4008H [ISE, 5.5 (5–7); FP, 4 (2.25–5.75); IC, 4 (2–5)]and F5008S [ISE, 4 (2–5); FP, 1 (−1–1.75); IC, 1 (−0.5 to 2)] mEq/L (P < 0.05). At higher programmed DNa (140–145 mEq/L), measured DNa was greater for the BB and F4008 machines by all methods (P < 0.05), but only by ISE for the F5008 (P < 0.05).

Conclusions

We noted a systematic bias in DNa delivery with measured DNa being greater than that programmed by our HD machines. The magnitude of the bias varied between machines and with DNa. Our results may help explain the diverse results reported in studies of DNa.

Individualized dialysate sodium prescriptions using sodium gradients for high-risk hemodialysis patients lowered interdialytic weight gain and achieved target weights

INTRODUCTION

Large interdialytic weight gain (IDWG) is associated with increased morbidity and mortality in chronic hemodialysis patients. Over 50% of patients at our inner city tertiary academic center dialysis unit had IDWG and target weights (TW) above goal. We conducted an open-label nonrandomized study to explore the effects of an individualized dialysate sodium (DNa) prescription using Na gradients in patients at high risk for large IDWG. Thirty-three patients receiving chronic hemodialysis received individualized DNa prescriptions with a DNa bath of 0 to -2 meq/L below their serum Na level in the intervention group, while patients in the control group were prescribed the standard dialysate Na at 138 mmol/L. Serum Na level, predialysis SBP, symptomatic hypotensive episodes, and %hemodialysis treatments with large IDWG (%TxAIDWG) and above TW(%TxATW) were recorded before and three months after the intervention. We used student t tests to compare continuous variables and Chi-square tests to compare binary variables between the groups at baseline and after the intervention. Age- and sex-adjusted linear regression models were also constructed to assess the differences in each continuous outcome between the groups. Multivariable logistic regression models were conducted by modeling IDWG decrease and above estimated-dry-weight (EDW) decrease as binary dependent variables with adjustment for age, sex, and EDW change.

FINDINGS

Patients with individualized DNa concentrations had 3.6 times greater odds of having lower IDWG than those with standard dialysate Na concentration. This significant association remained after adjustment for age, sex, and changes in EDW (OR: 3.63; 95% CI, 1.03-12.9). There was no difference in predialysis BP or symptomatic hypotensive episodes between the two groups.

DISCUSSION

Individualized DNa prescriptions appeared to be well tolerated and may be effective for optimal fluid management in high-risk hemodialysis patients.

The renal replacement therapy landscape in 2030: reducing the global cardiovascular burden in dialysis patients

Despite the significant progress made in understanding chronic kidney disease and uraemic pathophysiology, use of advanced technology and implementation of new strategies in renal replacement therapy, the clinical outcomes of chronic kidney disease 5 dialysis patients remain suboptimal. Considering residual suboptimal medical needs of short intermittent dialysis, it is our medical duty to revisit standards of dialysis practice and propose new therapeutic options for improving the overall effectiveness of dialysis sessions and reduce the burden of stress induced by the therapy. Several themes arise to address the modifiable components of the therapy that are aimed at mitigating some of the cardiovascular risks in patients with end-stage kidney disease. Among them, five are of utmost importance and include: (i) enhancement of treatment efficiency and continuous monitoring of dialysis performances; (ii) prevention of dialysis-induced stress; (iii) precise handling of sodium and fluid balance; (iv) moving towards heparin-free dialysis; and (v) customizing electrolyte prescriptions. In summary, haemodialysis treatment in 2030 will be substantially more personalized to the patient, with a clear focus on cardioprotection, volume management, arrhythmia surveillance, avoidance of anticoagulation and the development of more dynamic systems to align the fluid and electrolyte needs of the patient on the day of the treatment to their particular circumstances.

The relationship of volume overload and its control to hypertension in hemodialysis patients

Hypertension is highly prevalent and associated with poor clinical outcomes among individuals receiving maintenance hemodialysis (HD). Volume overload is a key modifiable contributor to hypertension and cardiovascular disease in the HD population. Despite their importance, assessment and treatment of volume overload and hypertension remain major clinical challenges and have substantial implications for both clinical outcomes and patient experiences of care. This review will summarize current data on the diagnosis, epidemiology, pathophysiology, and clinical consequences of hypertension and volume overload in HD patients. We will also identify priorities for future research studies.

Automated individualization of dialysate sodium concentration reduces intradialytic plasma sodium changes in hemodialysis

In standard care, hemodialysis patients are often treated with a center‐specific fixed dialysate sodium concentration, potentially resulting in diffusive sodium changes for patients with plasma sodium concentrations below or above this level. While diffusive sodium load may be associated with thirst and higher interdialytic weight gain, excessive diffusive sodium removal may cause intradialytic symptoms. In contrast, the new hemodialysis machine option “Na control” provides automated individualization of dialysate sodium during treatment with the aim to reduce such intradialytic sodium changes without the need to determine the plasma sodium concentration. This proof‐of‐principle study on sodium control was designed as a monocentric randomized controlled crossover trial: 32 patients with residual diuresis of ≤1000 mL/day were enrolled to be treated by high‐volume post‐dilution hemodiafiltration (HDF) for 2 weeks each with “Na control” (individually and automatically adjusted dialysate sodium concentration) versus “standard fixed Na” (fixed dialysate sodium 138 mmol/L), in randomized order. Pre‐ and post‐dialytic plasma sodium concentrations were determined at bedside by direct potentiometry. The study hypothesis consisted of 2 components: the mean plasma sodium change between the start and end of the treatment being within ±1.0 mmol/L for sodium‐controlled treatments, and a lower variability of the plasma sodium changes for “Na control” than for “standard fixed Na” treatments. Three hundred seventy‐two treatments of 31 adult chronic hemodialysis patients (intention‐to‐treat population) were analyzed. The estimate for the mean plasma sodium change was −0.53 mmol/L (95% confidence interval: [−1.04; −0.02] mmol/L) for “Na control” treatments and −0.95 mmol/L (95% CI: [−1.76; −0.15] mmol/L) for “standard fixed Na” treatments. The standard deviation of the plasma sodium changes was 1.39 mmol/L for “Na control” versus 2.19 mmol/L for “standard fixed Na” treatments (P = 0.0004). Whereas the 95% CI for the estimate for the mean plasma sodium change during “Na control” treatments marginally overlapped the lower border of the predefined margin ±1.0 mmol/L, the variability of intradialytic plasma sodium changes was lower during “Na control” versus “standard fixed Na” treatments. Thus, automated dialysate sodium individualization by “Na control” approaches isonatremic dialysis in the clinical setting.

Mechanisms, Clinical Implications, and Treatment of Intradialytic Hypotension

Individuals with ESKD requiring maintenance hemodialysis face a unique hemodynamic challenge, typically on a thrice-weekly basis. In an effort to achieve some degree of euvolemia, ultrafiltration goals often involve removal of the equivalent of an entire plasma volume. Maintenance of adequate end-organ perfusion in this setting is dependent on the institution of a variety of complex compensatory mechanisms. Unfortunately, secondary to a myriad of patient- and dialysis-related factors, this compensation often falls short and results in intradialytic hypotension. Physicians and patients have developed a greater appreciation for the breadth of adverse outcomes associated with intradialytic hypotension, including higher cardiovascular and all-cause mortality. In this review, we summarize the evidence for adverse outcomes associated with intradialytic hypotension, explore the underlying pathophysiology, and use this as a basis to introduce potential strategies for its prevention and treatment.

[The different modalities of isonatric hemodialysis]

Setting dialysate sodium allows to adequately adjust sodium balance and plasma sodium at the end of dialysis session. In accordance with the set-point theory based on the concept of restoring cellular hydration, an adequate target for plasma sodium at the end of the session could be the value of predialysis plasma sodium concentration (isonatric hemodialysis). Some recently available dialysis monitors provide an on-line value of plasma-water conductivity usually converted in on-line natremia. There are different modalities of isonatric hemodialysis depending on whether the online value of natremia is used or not. By reviewing the few studies concerning the isonatric hemodialysis, it seems logical to set a target of postdialysis on-line natremia (or plasma-water conductivity) slightly lower than its predialysis value. However this strategy requires specifically designed software not yet available in clinical routine.

Associations between dialysate sodium concentration and plasma sodium concentration of dogs receiving intermittent hemodialysis treatments

OBJECTIVE To compare dialysate sodium concentration and patient plasma sodium concentration of dogs during intermittent hemodialysis treatments. SAMPLE 211 intermittent hemodialysis treatments performed on 40 client-owned dogs for the management of dialysis-dependent uremia. PROCEDURES Medical records were reviewed to determine the plasma sodium concentration of each dog before and after routine hemodialysis treatments. Associations between detected changes in plasma sodium concentration and dialysate sodium concentration were evaluated by use of Spearman rank correlations and linear regression analysis. RESULTS Significant linear correlations were found between the dialysate sodium concentration and patient sodium concentration. The starting dialysate-to-patient sodium gradient was associated with the strongest correlation to the change in patient sodium concentration at the end of the dialysis session. Modest correlations existed between the dialysate sodium concentration and postdialysis patient sodium concentration as well as between the predialysis dialysate-to-patient sodium gradient and postdialysis dialysate-to-patient sodium gradient. CONCLUSIONS AND CLINICAL RELEVANCE The dialysate sodium concentration was correlated with the patient sodium concentration in dogs, and the dialysate-to-patient sodium gradient could be used to further refine this association to predict the postdialysis patient sodium concentration and potentially manage dysnatremia during hemodialysis. Prospective studies should be performed to determine how these associations can be used to correct aberrations as well as to avoid unwanted alterations in patient sodium concentrations.

Osmolality and blood pressure stability during hemodialysis

Homeostatic regulation of plasma osmolality (POsm) is critical for normal cellular function in humans. Arginine vasopressin (AVP) is the major hormone responsible for the maintenance of POsm and acts to promote renal water retention in conditions of increased POsm. However, AVP also exerts pressor effects, and its release can be stimulated by the development of effective arterial blood volume depletion. Patients with end-stage renal disease on hemodialysis, particularly those with minimal or no residual renal function, have impaired ability to regulate water retention in response to AVP. While hemodialysis can assist with this task, patients are subject to relatively rapid shifts in volume and electrolytes during the procedure. This can result in the development of transient osmotic gradients that lead to the movement of water from the extracellular to the intracellular space. Hypotension may result-both as a consequence of water movement out of the intravascular compartment, but also from impaired AVP release and inadequate vascular tone. In this review, we explore the evidence for POsm changes during hemodialysis, associations with adverse outcomes, and methods to minimize the rapidity of changes in POsm in an effort to reduce patient symptoms and minimize intra-dialytic hypotension.

Dialysate Composition for Hemodialysis: Changes and Changing Risk

Dialysate composition is a critical aspect of the hemodialysis prescription. Despite this, trial data are almost entirely lacking to help guide the optimal dialysate composition. Often, the concentrations of key components are chosen intuitively, and dialysate composition may be determined by default based on dialysate manufacturer specifications or hemodialysis facility practices. In this review, we examine the current epidemiological evidence guiding selection of dialysate bicarbonate, calcium, magnesium, and potassium, and identify unresolved issues for which pragmatic clinical trials are needed.