Impact of fluid status and inflammation and their interaction on survival: a study in an international hemodialysis patient cohort

Vitamin D Effects on Bone Homeostasis and Cardiovascular System in Patients with Chronic Kidney Disease and Renal Transplant Recipients

Poor vitamin D status is common in patients with impaired renal function and represents one main component of the complex scenario of chronic kidney disease-mineral and bone disorder (CKD-MBD). Therapeutic and dietary efforts to limit the consequences of uremia-associated vitamin D deficiency are a current hot topic for researchers and clinicians in the nephrology area. Evidence indicates that the low levels of vitamin D in patients with CKD stage above 4 (GFR < 15 mL/min) have a multifactorial origin, mainly related to uremic malnutrition, namely impaired gastrointestinal absorption, dietary restrictions (low-protein and low-phosphate diets), and proteinuria. This condition is further worsened by the compromised response of CKD patients to high-dose cholecalciferol supplementation due to the defective activation of renal hydroxylation of vitamin D. Currently, the literature lacks large and interventional studies on the so-called non-calcemic activities of vitamin D and, above all, the modulation of renal and cardiovascular functions and immune response. Here, we review the current state of the art of the benefits of supplementation with native vitamin D in various clinical settings of nephrological interest: CKD, dialysis, and renal transplant, with a special focus on the effects on bone homeostasis and cardiovascular outcomes.

Bioimpedance analysis is not superior to clinical assessment in determining hydration status: A prospective randomized-controlled trial in a Western dialysis population

INTRODUCTION

Fluid management is an important goal of dialysis treatment. The accurate assessment of fluid status is still a challenge for clinical nephrologists. Bioimpedance analysis (BIA) has been proposed as an objective tool to assess hydration.

METHODS

This was a prospective randomized controlled study to compare hydration status measured by clinical assessment compared to BIA using a body composition monitor (BCM). The primary outcome was defined as the decline of cardiac biomarker N-terminal pro brain natriuretic peptide (NT-proBNP) from baseline to the end of the study.

FINDINGS

About 281 chronic hemodialysis patients were assessed for eligibility, and 132 patients provided written informed consent to participate (65 BIA group, 67 clinical group). Predialytic NT-proBNP, and decline of NT-proBNP were similar in both groups. The amount of overhydration (2.18 ± 2.11 L vs. 1.29 ± 1.97 L; p 0.016) and the number of patients with severe overhydration (46.0% vs. 30.6%, p = 0.04) were significantly higher in the BIA group at the end of the study. Fluid accumulation in the interdialytic period was significantly lower in the clinical group (p = 0.013). Adverse events occurred more often in the BIA group (p = 0.032). The cumulative number of hypovolemic events was significantly higher in the BIA group (p = 0.002).

DISCUSSION

Fluid management by BIA does not lead to a better cardiac outcome (appraised by surrogate markers) than fluid management by careful clinical assessment. Adapting the dry weight according to BIA results increases the risk of adverse events, especially hypovolemic episodes. Careful clinical fluid assessment is important for optimal care of chronic hemodialysis patients.

The cholinergic anti-inflammatory pathway in chronic kidney disease-review and vagus nerve stimulation clinical pilot study

Inflammation and autonomic dysfunction are common findings in chronic and end-stage kidney disease and contribute to a markedly increased risk of mortality in this patient population. The cholinergic anti-inflammatory pathway (CAP) is a vagal neuro-immune circuit that upholds the homoeostatic balance of inflammatory activity in response to cell injury and pathogens. CAP models have been examined in preclinical studies to investigate its significance in a range of clinical inflammatory conditions and diseases. More recently, cervical vagus nerve stimulation (VNS) implants have been shown to be of potential benefit for patients with chronic autoimmune diseases such as rheumatoid arthritis and inflammatory bowel disease. We have previously shown that dialysis patients have a functional CAP ex vivo. Here we review the field and the potential role of the CAP in acute kidney injury and chronic kidney disease (CKD) as well as in hypertension. We also present a VNS pilot study in haemodialysis patients. Controlling inflammation by neuroimmune modulation may lead to new therapeutic modalities for improved treatment, outcome, prognosis and quality of life for patients with CKD.

Association of N-Terminal Pro-brain Natriuretic Peptide With Volume Status and Cardiac Function in Hemodialysis Patients

Introduction: N-terminal-pro-brain natriuretic peptide (NT-pro BNP) is secreted by cardiomyocytes in cases of cardiac structure disorder and volume overload. However, the relationship between NT-pro BNP level and body fluid status in dialysis patients with reduced cardiac ejection function (EF) is uncertain. Therefore, we aimed to investigate this relationship.

Methods: We enrolled patients who had been receiving hemodialysis for >3 months. Blood sample, transthoracic echocardiographic, and bioimpedance spectroscopy measurements were performed during a midweek non-dialysis day. The predictive value of NT-pro BNP in hemodialysis patients with volume overload was analyzed.

Results: A total of 129 hemodialysis patients (74 men and 55 women; mean age: 59.4 ± 13.0 years) were recruited. The average hemodialysis duration was 55.5 (23.9–93.4) months, the NT-pro BNP level was 4992 (2,033–15,807) pg/mL, and the value of overhydration was 2.68 ± 0.19 (−1.9 to 12.2) L. The NT-pro BNP level was independently correlated with overhydration in both the LVEF ≥ 60% (β = 0.236, P = 0.044) and LVEF <60% (β = 0.516, P = 0.032) groups, even after adjustments for potentially confounding variables. In receiver operating characteristic curves of NT-pro BNP for predicting volume overload, the area under the curve was 0.783 [95% CI (0.688–0.879), P < 0.001) and 0.788 [95% CI (0.586–0.989), P < 0.001] in the LVEF ≥ 60% and LVEF < 60% groups, respectively.

Conclusions: NT-pro BNP is a predictive factor for volume overload in hemodialysis patients with or without EF declines.

On the potential of wearable bioimpedance for longitudinal fluid monitoring in end-stage kidney disease

Bioimpedance spectroscopy (BIS) has proven to be a promising non-invasive technique for fluid monitoring in HD patients. While current BIS-based monitoring of pre- and post-dialysis fluid status utilizes benchtop devices, designed for intramural use, advancements in micro-electronics have enabled the development of wearable bioimpedance systems. Wearable systems meanwhile can offer a similar frequency range for current injection as commercially available benchtop devices. This opens opportunities for unobtrusive longitudinal fluid status monitoring, including transcellular fluid shifts, with the ultimate goal of improving fluid management, thereby lowering mortality and improving quality of life for HD patients. Ultra-miniaturized wearable devices can also offer simultaneous acquisition of multiple other parameters, including hemodynamic parameters. Combination of wearable BIS and additional longitudinal multiparametric data may aid in the prevention of both hemodynamic instability as well as fluid overload. The opportunity to also acquire data during interdialytic periods using wearable devices likely will give novel pathophysiological insights and the development of smart (predicting) algorithms could contribute to personalizing dialysis schemes and ultimately to autonomous (nocturnal) home dialysis. This review provides an overview of current research regarding wearable bioimpedance, with special attention to applications in ESKD patients. Furthermore, we present an outlook on the future use of wearable bioimpedance within dialysis practice.

Are there any further modalities for prediction of subclinical volume overload in advanced stages of chronic kidney disease?

BACKGROUND

Subclinical volume overload in chronic kidney disease (CKD) patient represents a debatable issue. Although many tools were used to detect volume overload in such patients, many non-specific results were due to presence of comorbidities. Bioimpedance spectroscopy is an objective fluid status assessment method, which is shown superior to classical methods in many studies. Combining some of these tools may improve their accuracy and specificity. Inferior vena cava collapsibility index (IVCCI) with brain natriuretic peptide (BNP) can be combined for more specific volume assessment. This study was performed to assess the usage of combined IVCCI and BNP levels in CKD patients to predict subclinical volume overload.

METHODS

One hundred and ten patients with CKD (stages 4 and 5) not on dialysis and having normal left ventricular systolic function were included in this study. Exclusion criteria were: (1) patients with other causes of raised BNP than volume overload and (2) patients on diuretics. A complete medical history was obtained, and thorough examination and laboratory tests were performed for all included patients. IVCCI and BNP serum levels were evaluated. The patients who exhibited an overhydration (OH)/extracellular water (ECW) ratio of >15% were considered to have volume overload.

RESULTS

Twenty-six patients (23.6%) had subclinical hypervolemia as diagnosed by OH/ECW ratio of >15%. IVCCI ≤ 38% had higher diagnostic performance than BNP ≥ 24 pg/mL. Combining both IVCCI ≤ 38% and BNP ≥ 24 pg/mL increased the specificity and positive predictive value for detection of subclinical hypervolemia.

CONCLUSION

Combined elevated BNP level and decreased IVCCI are more precise tools for subclinical volume overload detection in CKD patients.

Comparison of lung ultrasound and other volumetric methods in peritoneal dialysis patients

Although many alternative methods are present, maintaining ideal volume status in peritoneal dialysis (PD) patients still rely on clinical evaluation due to lack of an evidence-based method. Lung ultrasound (LUS) is a new method for evaluation of hidden congestion in this group.LUS findings and its relationship with other volumetric methods are investigated in this observational cross-sectional study.In this observational cross sectional study, LUS was performed to all PD patients and compared with symptoms of hypervolemia, physical examination, vascular endothelial growth factor-C (VEGF-C), and N-terminal pro-brain natriuretic peptide levels, chest radiography, echocardiography, bioelectrical impedance analysis.Data of 21 PD patients were evaluated. There was correlation between number of B lines and VEGF-C levels (r = 0.447, P = .042), daily urine output (r = 0.582, P = .007) and left ventricle mass index (r = -0.456, P = .038). Correlations with all other parameters were not significant. Daily urine output and VEGF-C levels were significantly different when B lines were grouped into 2 according to the median level (P < .05 for all).This is the widest spectrum study looking for LUS findings and other volumetric parameters in a small PD cohort. LUS might be useful to evaluate hidden hypervolemia. Its correlation with VEGF-C level is a novel finding.

Comparison between dual-energy x-ray absorptiometry and bioelectrical impedance for body composition measurements in adults with chronic kidney disease: A cross-sectional, longitudinal, multi-treatment analysis

OBJECTIVE

The aim of this study was to evaluate the agreement between bioelectrical impedance spectroscopy (BIS) and dual-energy x-ray absorptiometry (DXA) for assessment of body composition in patients with chronic kidney disease (CKD).

METHODS

We performed cross-sectional and prospective analyses by DXA and BIS in whole body (BISWB) and segmental (BISSEG) protocols in CKD non-dialysis-dependent (n = 81), hemodialysis (n = 83), peritoneal dialysis (n = 24), and renal transplantation (n = 80) patients. Intraclass correlation coefficient (ICC) and Bland-Altman plots were evaluated. Linear regression analysis was performed for bias assessment and development of equations. Receiver operating characteristics curve was constructed for diagnosis of inadequate error tolerance (DXA - BIS >±2kg).

RESULTS

The agreement with DXA was greater for BISWB than BISSEG; for fat mass (FM; ICC men = 0.894; women = 0.931) than fat-free mass (FFM; ICC men = 0.566; women = 0.525), with greater bias for FFM as muscle increases and for FM in body fat extremes. The agreement was lower for body change analysis (ICC FFM men = 0.196; women = 0.495; ICC FM men = 0.465; women = 0.582). The ratio of extra- to intracellular water (ECW/ICW), body mass index, fat mass index, waist circumference, resistance, and reactance interfered in bias between methods. An ECW/ICW cutoff point of ≥0.7250 for inadequate error tolerance was determined. New prediction equations for FFM (r² = 0.913) and FM (r² = 0.887) presented adequate error tolerance in 55% and 63% compared with 30% and 39% of the original equation, respectively.

CONCLUSION

For body composition evaluation in patients with CKD, BIS applied using the whole body protocol, in normal hydration patients with CKD is as reliable as DXA; BIS must be used with caution in overhydration patients with ECW/ICW ≥ 0.7250. The newly developed equations are indicated for greater precision.

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.

Low Intracellular Water, Overhydration, and Mortality in Hemodialysis Patients

Background: In hemodialysis patients, extracellular water (ECW) overload predicts all-cause and cardiovascular mortality. The primary aim of the present study was to analyze changes in post-dialysis (i.e., following removal of excess ECW) ECW, intracellular water (ICW), and the overhydration (OH) parameter over time. Additionally, the association of these parameters with mortality was explored. Patients and methods: Prospective study of prevalent hemodialysis patients (n = 124) followed for a median of 20 (interquartile range (IQR) 8–31) months. In three visits, inflammation (C-reactive protein) and post-dialysis fluid status (bioimpedance, BIS) were assessed. Results: During follow-up, the overhydration (OH) parameter increased (−0.696 ± 1.6 vs. 0.268 ± 1.7 L; p = 0.007) at the expense of a decrease in intracellular water (ICW) (19.90 ± 4.5 vs. 18.72 ± 4.1 24 L; p = 0.006) with a non-significant numerical increase in ECW/ICW ratio (0.795 ± 0.129 vs. 0.850 ± 0.143; p = 0.055). Baseline ICW positively correlated with muscle mass and energy intake and negatively with C-reactive protein and it was lower in those who died than in survivors (15.09 ± 2.36 vs. 18.87 ± 4.52 L; p = 0.004). In Kaplan–Meier analysis, patients with low baseline ICW (≤17 L) and high ECW/ICW ratio (≥0.84) were at an increased risk of death. Baseline ICW was also associated with the risk of death in adjusted Cox proportional hazards models (HR 0.62 (0.40–0.98) p = 0.04). Conclusions: In hemodialysis patients, the post-dialysis OH parameter increased over time while ICW decreased, without changes in ECW. Low baseline post-dialysis ICW correlated with muscle wasting and inflammation and was an independent risk factor for mortality.

The impact of the Christmas holiday effect on interdialytic weight gain in hemodialysis patients: A multicenter observational retrospective cohort study

INTRODUCTION

The 3-day interdialytic interval (IDI) is associated with high interdialytic weight gain (IDWG), but little is known about the effect of public or religious holidays on IDWG. Consequently, we evaluated the impact of the "Christmas holiday effect" on IDWG of hemodialysis patients.

METHODS

A retrospective cohort study of adult hemodialysis patients (over 18 years) was conducted across five dialysis units in Australia. Demographic and clinical data were collected from electronic medical records. IDWG was established for three time points; regular 3-day IDI, 2-day IDI preceding the Christmas holiday and a 3-day IDI that included the Christmas holiday. Paired t-tests and logistic regression were used to compare differences in mean IDWG before and after the Christmas holiday and to examine factors associated with high IDWG, respectively.

FINDINGS

Two hundred and fifty-two patients, 69% of whom were male, with mean (SD) age of 65.4 ± 15.3 years, were studied. Most had end-stage kidney disease due to diabetes (44%), and they had been on hemodialysis for a median of 25.5 (IQR, 60-10) months. There was a significant increase in absolute IDWG (MD 0.21 kg, 95% CI -0.07 to 0.36; P = 0.004) and relative IDWG (MD 0.3%, 95% CI 0.10-0.40; P = 0.01) after the holiday 3-day IDI compared with the regular 3-day IDI. Older age (OR 0.12; 95% CI 0.02-0.55) and a unit increase in hemoglobin (OR 0.94; 95% CI 0.89-0.99) were associated with lower odds of high relative IDWG while speaking a language other than English increased the odds for high relative IDWG (OR 5.03; 95% CI 1.12-22.65).

CONCLUSION

Absolute and relative IDWG increased significantly after the Christmas holiday. Individualizing dialysis needs may improve outcomes for these patients.

Implementation of a decision aid for recognition and correction of volume alterations (Recova®) in haemodialysis patients

BACKGROUND

Fluid overload is associated with mortality in haemodialysis patients, and 30% of patients remain fluid-overloaded after dialysis. The aim of this study was to evaluate if implementation of Recova^®, a decision aid combining clinical assessment with bioimpedance spectroscopy, facilitates individualization of target weight determination and thereby contributes to improved fluid status in maintenance haemodialysis patients.

METHODS

The impact of the implementation was measured as the proportion of participants at an adequate target weight at the end of the study, assessed as change in symptoms, hydration status, and N-terminal pro-brain natriuretic peptide (NT-proBNP). Nurses were instructed to use Recova every 2 weeks, and the process of the intervention was measured as frequencies of fluid status assessments, bioimpedance measurements, and target weight adjustments.

RESULTS

Forty-nine patients at two haemodialysis units were enrolled. In participants with fluid overload (n = 10), both overhydration and fluid overload symptom score decreased. In fluid-depleted participants (n = 20), target weight adjustment frequency and the estimated target weight increased. The post-dialytic negative overhydration was reduced, but NT-proBNP increased.

CONCLUSIONS

Implementation of Recova in haemodialysis care increased the monthly frequencies of bioimpedance measurements and target weight adjustments, and it contributed to symptom reduction.

TRIAL REGISTRATION

The Uppsala County Council Registry of Clinical Trials: FoU 2019-0001-15.

Dialysis-Induced Cardiovascular and Multiorgan Morbidity

Hemodialysis has saved many lives, albeit with significant residual mortality. Although poor outcomes may reflect advanced age and comorbid conditions, hemodialysis per se may harm patients, contributing to morbidity and perhaps mortality. Systemic circulatory "stress" resulting from hemodialysis treatment schedule may act as a disease modifier, resulting in a multiorgan injury superimposed on preexistent comorbidities. New functional intradialytic imaging (i.e., echocardiography, cardiac magnetic resonance imaging [MRI]) and kinetic of specific cardiac biomarkers (i.e., Troponin I) have clearly documented this additional source of end-organ damage. In this context, several factors resulting from patient-hemodialysis interaction and/or patient management have been identified. Intradialytic hypovolemia, hypotensive episodes, hypoxemia, solutes, and electrolyte fluxes as well as cardiac arrhythmias are among the contributing factors to systemic circulatory stress that are induced by hemodialysis. Additionally, these factors contribute to patients' symptom burden, impair cognitive function, and finally have a negative impact on patients' perception and quality of life. In this review, we summarize the adverse systemic effects of current intermittent hemodialysis therapy, their pathophysiologic consequences, review the evidence for interventions that are cardioprotective, and explore new approaches that may further reduce the systemic burden of hemodialysis. These include improved biocompatible materials, smart dialysis machines that automatically may control the fluxes of solutes and electrolytes, volume and hemodynamic control, health trackers, and potentially disruptive technologies facilitating a more personalized medicine approach.

Hemodialysis crossover study using a relative blood volume change-guided ultrafiltration control compared with standard hemodialysis: the BV-UFC study

Background

It has been difficult to sufficiently achieve body-fluid management using blood volume (BV) monitor during hemodialysis (HD) with constant ultrafiltration (UF) rate. Recently, a relative BV change-guided UF control (BV-UFC) system was developed by combining the concepts of an automatic feedback system that could control the UF rate and profile with real- time monitoring of relative changes in BV (%ΔBV). However, this system has limited application in the clinical setting. Therefore, in this study, we aimed to perform the crossover study on HD with BV-UFC compared to standard HD in terms of hemodynamic stability during HD.

Methods

Forty-eight patients entered an 8-week crossover period of standard HD or HD with BV-UFC. Prevalence of intradialytic hypotension (IDH) as a primary outcome and changes in blood pressure (BP), differences in %ΔBV, and achievement of the target ultrafiltration volume as secondary outcomes were compared. IDH was defined as a reduction in systolic BP ≥20 mmHg from the baseline value at 10 min after HD initiation.

Results

No significant differences were found in the prevalence of IDH, frequency of intervention for symptomatic IDH, and achievement of the target ultrafiltration volume between the groups. The %ΔBV was significantly fewer (-12.1 ± 4.8% vs. -14.4 ± 5.2%, p <0.001) in the HD with BV-UFC than that in the standard HD.

Conclusions

HD with BV-UFC did not reduce the prevalence of IDH compared with standard HD. The relief of a relative BV reduction at the end of HD may be beneficial in patients undergoing HD with BV-UFC.

Trial Registration

UMIN, UMIN000024670. Registered on December 1, 2016.

Higher-order clinical risk factor interaction analysis for overall mortality in maintenance hemodialysis patients

BACKGROUND AND AIMS

In Taiwan, approximately 90% of patients with end-stage renal disease receive maintenance hemodialysis. Although studies have reported the survival predictability of multiclinical factors, the higher-order interactions among these factors have rarely been discussed. Conventional statistical approaches such as regression analysis are inadequate for detecting higher-order interactions. Therefore, this study integrated receiver operating characteristic, logistic regression, and balancing functions for adjusting the ratio in risk classes and classification errors for imbalanced cases and controls using multifactor-dimensionality reduction (MDR-ER) analyses to examine the impact of interaction effects between multiclinical factors on overall mortality in patients on maintenance hemodialysis.

METERIALS AND METHODS

In total, 781 patients who received outpatient hemodialysis dialysis three times per week before 1 January 2009 were included; their baseline clinical factor and mortality outcome data were retrospectively collected using an approved data protocol (201800595B0).

RESULTS

Consistent with conventional statistical approaches, the higher-order interaction model could indicate the impact of potential risk combination unique to patients on maintenance hemodialysis on the survival outcome, as described previously. Moreover, the MDR-based higher-order interaction model facilitated higher-order interaction effect detection among multiclinical factors and could determine more detailed mortality risk characteristics combinations.

CONCLUSION

Therefore, higher-order clinical risk interaction analysis is a reasonable strategy for detecting non-traditional risk factor interaction effects on survival outcome unique to patients on maintenance hemodialysis and thus clinically achieving whole-scale patient care.

Multi-Method Complex Approach for Hydration Assessment Does Not Detect a Hydration Difference in Hemodialysis versus Peritoneal Dialysis Patient

Assessment of hydration status is essential in monitoring the effectiveness of renal replacement therapy and is usually based on physical examination. However, comparisons of hydration status achieved with different dialysis methods are not conclusive. We compared the hydration status of patients on chronic hemodialysis (HD, n = 60) and peritoneal dialysis (PD, n = 20) in a comprehensive assessment including physical examination and additional methods. The mean age of the 80 chronically dialyzed patients (53 males, 27 females) was 58.1 ± 13.9 years. The clinical evaluation took into account the presence of peripheral edema, dyspnea, and crackling over the lung fields. Additional tests included lung ultrasound, electrical bioimpedance (performed in 79 patients), impedance cardiography, ultrasound assessment of large abdominal vessels (performed in 79 patients), select echocardiographic parameters (obtained in 78 patients), and serum NT-proBNP concentration. Residual diuresis volume was significantly higher in the PD group. We found no significant differences between the two groups in any other baseline characteristics or in the results of the clinical examination or additional tests. The use of different methods for assessing hydration does not allow differentiation of patients treated with dialysis in terms of the dialysis technique used. Therefore, it seems reasonable to use common algorithms to objectify the hydration status of these 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.

Wearable health devices and personal area networks: can they improve outcomes in haemodialysis patients?

Digitization of healthcare will be a major innovation driver in the coming decade. Also, enabled by technological advancements and electronics miniaturization, wearable health device (WHD) applications are expected to grow exponentially. This, in turn, may make 4P medicine (predictive, precise, preventive and personalized) a more attainable goal within dialysis patient care. This article discusses different use cases where WHD could be of relevance for dialysis patient care, i.e. measurement of heart rate, arrhythmia detection, blood pressure, hyperkalaemia, fluid overload and physical activity. After adequate validation of the different WHD in this specific population, data obtained from WHD could form part of a body area network (BAN), which could serve different purposes such as feedback on actionable parameters like physical inactivity, fluid overload, danger signalling or event prediction. For a BAN to become clinical reality, not only must technical issues, cybersecurity and data privacy be addressed, but also adequate models based on artificial intelligence and mathematical analysis need to be developed for signal optimization, data representation, data reliability labelling and interpretation. Moreover, the potential of WHD and BAN can only be fulfilled if they are part of a transformative healthcare system with a shared responsibility between patients, healthcare providers and the payors, using a step-up approach that may include digital assistants and dedicated ‘digital clinics’. The coming decade will be critical in observing how these developments will impact and transform dialysis patient care and will undoubtedly ask for an increased ‘digital literacy’ for all those implicated in their care.

Clinical impact of disease-related malnutrition and fluid overload assessment via bioimpedance vector analysis in hospitalized patients

BACKGROUND

This cohort study assessed the effect of disease-related malnutrition (DRM) and fluid overload (FO) evaluated by bioimpedance vector analysis (BIVA) on mortality among hospitalized patients.

METHODS

We examined adult patients hospitalized in an internal medicine ward. The malnutrition risk was assessed using the NRS2002 questionnaire, and body composition was estimated via BIVA. Clinical, epidemiological, and laboratory characteristics were compared between patients with and without DRM by BIVA (DRM-B). The effect of DRM and FO by BIVA on mortality was assessed via logistic regression analysis.

RESULTS

The study included 130 adult patients (62.3% men) with a mean age of 63 ± 19 years. Malnutrition risk at hospital admission was present in 43.8%. According to BIVA, 63.1% had normal body composition, 27.7% had DRM, and 9.2% obesity while FO was present in 53.1%. Patients with DRM-B were older (70 ± 16 vs. 61 ± 20 years, p = 0.05) and had a higher prevalence of cerebrovascular disease than patients without DRM-B (11% vs. 0%, p = 0.001). The overall mortality rate was 8.5% (n = 11) and was higher among patients with DRM-B than among those without DRM-B (16.7% vs. 5.3%, p = 0.03). No differences existed in mortality between patients with and without FO (8.7% vs. 8.2%, p = 0.91). DRM-B was associated with higher mortality rates adjusted for FO and comorbidities (odds ratio = 3.7, 95% confidence interval: 1.01-13.53, p = 0.04).

CONCLUSION

DRM and FO by BIVA were very frequent in our population. DRM-B was associated with a higher mortality rate, which emphasizes the importance of evaluating body composition in hospitalized patients.

An acute rise of plasma Na+ concentration associates with syndecan-1 shedding during hemodialysis

Endothelial dysfunction (ED) contributes to the high incidence of cardiovascular events in patients undergoing hemodialysis. Syndecan-1 in the endothelial glycocalyx can be shed into the circulation, serving as a biomarker for ED. As Na+ is a trigger for glycocalyx shedding, we now tested whether hemodialysis, with higher dialysate Na+ concentrations, is associated with more syndecan-1 shedding compared with standard hemodialysis (SHD). In this crossover study in 29 patients, plasma syndecan-1 was repeatedly measured during SHD and during Hemocontrol hemodialysis (HHD), which is characterized by initially higher dialysate and plasma Na+ levels. Courses of syndecan-1 were compared with linear mixed models. Syndecan-1 shedding was assessed by area under the curve analysis. Plasma Na+ increased early after the start of SHD and HHD, with higher values during HHD (30 min: 142.3 vs. 139.9 mM, P < 0.001). Syndecan-1 increased significantly during both conditions, but the percent change was higher (42.9% vs. 19.5%) and occurred earlier (120 vs. 180 min) during HHD. Syndecan-1 levels were significantly higher at 120 min during HHD compared with SHD ( P < 0.05). Overall, syndecan-1 shedding was higher during HHD compared with SHD (means: 40.4 vs. 19.0 arbitrary units, P = 0.06). Lower predialysis plasma Na+ and osmolality were associated with greater intradialytic increases in syndecan-1 levels (both groups, P = 0.001). The rise in plasma syndecan-1 levels was more pronounced and occurred earlier during hemodialysis with higher plasma Na+ levels. Although we cannot prove that the rise in plasma syndecan-1 originates from the endothelial glycocalyx, our findings are compatible with Na+-driven endothelial glycocalyx-derived syndecan-1 shedding.

Assessment of Hydration Status in Peritoneal Dialysis Patients: Validity, Prognostic Value, Strengths, and Limitations of Available Techniques

BACKGROUND

The majority of patients undergoing peritoneal dialysis (PD) suffer from volume overload and this overhydration is associated with increased mortality. Thus, optimal assessment of volume status in PD is an issue of paramount importance. Patient symptoms and physical signs are often unreliable indexes of true hydration status.

SUMMARY

Over the past decades, a quest for a valid, reproducible, and easily applicable technique to assess hydration status is taking place. Among existing techniques, inferior vena cava diameter measurements with echocardiography and natriuretic peptides such as brain natriuretic peptide and N-terminal pro-B-type natriuretic peptide were not extensively examined in PD populations; while having certain advantages, their interpretation are complicated by the underlying cardiac status and are not widely available. Bioelectrical impedance analysis (BIA) techniques are the most studied tool assessing volume overload in PD. Volume overload assessed with BIA has been associated with technique failure and increased mortality in observational studies, but the results of randomized trials on the value of BIA-based strategies to improve volume-related outcomes are contradictory. Lung ultrasound (US) is a recent technique with the ability to identify volume excess in the critical lung area. Preliminary evidence in PD showed that B-lines from lung US correlate with echocardiographic parameters but not with BIA measurements. This review presents the methods currently used to assess fluid status in PD patients and discusses existing data on their validity, applicability, limitations, and associations with intermediate and hard outcomes in this population. Key Message: No method has proved its value as an intervening tool affecting cardiovascular events, technique, and overall survival in PD patients. As BIA and lung US estimate fluid overload in different compartments of the body, they can be complementary tools for volume status assessment.

[Natriuretic peptides in dialysis: From theory to clinical practice]

Cardiologists and emergency-wards physicians are used to check natriuretic peptides serum level, mainly B-type natriuretic peptide and N-terminal pro-Brain natriuretic peptide for acute cardiac failure diagnosis. Due to their accumulation in chronic kidney disease and their elimination by dialysis, natriuretic peptides sampling remains debatable in chronic kidney disease patients. In dialysis patients, high natriuretic peptides values are associated with mortality, left ventricular hypertrophy and cardiac failure. However, a single value cannot provide a reliable diagnosis. Our clinical practice is as follows: First, we prefer B-type natriuretic peptide to N-terminal pro-Brain natriuretic peptide because of its shorter half-life, with less impact of renal function and dialysis, making its interpretation easier in case of advanced chronic kidney disease or in dialysis patients; second, we define a reference value of B-type natriuretic peptide at dry weight from serial measurements; third, the B-type natriuretic peptide changes are interpreted according to extracellular fluid and cardiac status, but also from the arteriovenous fistula blood flow. In stable dialysis patients, B-type natriuretic peptide is sampled monthly and weekly in unstable patients. We illustrate our experience using clinical cases of overhydration, new cardiac disease onset, hypovolemia and arteriovenous fistula with high blood flow. Longitudinal follow-up of B-type natriuretic peptide is an important advance in dialysis patients in order to detect and treat extracellular fluid variations and cardiac disease status early, both important factors associated with hard outcomes.

An analysis of the impact of fluid overload and fluid depletion for all-cause and cardiovascular mortality

BACKGROUND

Both baseline fluid overload (FO) and fluid depletion are associated with increased mortality risk and cardiovascular complications in haemodialysis patients. Fluid status may vary substantially over time, and this variability could also be associated with poor outcomes.

METHODS

In our retrospective cohort study, including 4114 haemodialysis patients from 34 Romanian dialysis units, we investigated both all-cause and cardiovascular mortality risk according to baseline pre- and post-dialysis volume status, changes in pre- and post-dialysis fluid status during follow-up (time-varying survival analysis), pre-post changes in volume status during dialysis and pre-dialysis fluid status variability during the first 6 months of evaluation.

RESULTS

According to their pre-dialysis fluid status, patients were stratified in the following groups: normovolaemic with an absolute FO (AFO) compartment between -1.1 and 1.1 L, fluid depletion with an AFO below -1.1 L, moderate FO with an AFO compartment >1.1 but <2.5 L and severe FO with the AFO compartment >2.5 L. Baseline pre-dialysis FO and fluid depletion patients had a significantly elevated risk of all-cause mortality risk {hazard ratio [HR] 1.53 [95% confidence interval (CI) 1.22-1.93], HR 2.04 (95% CI 1.59-2.60) and HR 1.88 (95% CI 1.07-3.39) for moderate FO, severe FO and fluid depletion, respectively}. In contrast, post-dialysis fluid depletion was associated with better survival [HR 0.71 (95% CI 0.57-0.89)]. Similar results were found when using changes in pre- or post-dialysis fluid status during follow-up (time-varying values): FO patients had an increased risk of all-cause [moderate FO: HR 1.39 (95% CI 1.11-1.75); severe FO: HR 2.29 (95% CI 2.01-3.31] and cardiovascular (CV) mortality [moderate FO: HR 1.34 (95% CI 1.05-1.70); severe FO: HR 2.34 (95% CI 1.67-3.28)] as compared with normohydrated patients. Using pre-post changes in volume status during dialysis, we categorized the patients into six groups: Group 1, AFO <-1.1 L pre- and post-dialysis; Group 2, AFO between -1.1 and 1.1 L pre-dialysis and <-1.1 L post-dialysis (the reference group); Group 3, AFO between -1.1 and 1.1 L pre- and post-dialysis; Group 4, AFO >1.1 L pre-dialysis and <-1.1 L post-dialysis; Group 5, AFO >1.1 L pre-dialysis and between -1.1 and 1.1 L post-dialysis; Group 6, AFO >1.1 L pre- and post-dialysis. Using the baseline values, only patients in Groups 1, 5 and 6 maintained an increased risk for all-cause mortality as compared with the reference group. Additionally, CV mortality risk was significantly higher for patients in Groups 5 and 6. When we applied the time-varying analysis, patients in Groups 1, 5 and 6 had a significantly higher risk for both all-cause and CV mortality risk. In the last approach, the highest risk for the all-cause mortality outcome was observed for patients with high-amplitude fluctuation during the first 6 months of evaluation [HR 2.75 (95% CI 1.29-5.84)].

CONCLUSION

We reconfirm the association between baseline pre- and post-dialysis volume status and mortality in dialysis patients; additionally, we showed that greater fluid status variability is independently associated with higher mortality.

All-cause mortality in relation to changes in relative blood volume during hemodialysis

Background

Relative blood volume (RBV) monitoring is widely used in hemodialysis (HD) patients, yet the association between intradialytic RBV and mortality is unknown.

Methods

Intradialytic RBV was recorded once/min during a 6-month baseline period; all-cause mortality was noted during follow-up. RBV at 1, 2 and 3 h into HD served as a predictor of all-cause mortality during follow-up. We employed Kaplan–Meier analysis, univariate and adjusted Cox proportional hazards models for survival analysis.

Results

We studied 842 patients. During follow-up (median 30.8 months), 249 patients (29.6%) died. The following hourly RBV ranges were associated with improved survival: first hour, 93–96% [hazard ratio (HR) 0.58 (95% confidence interval (CI) 0.42–0.79)]; second hour, 89–94% [HR 0.54 (95% CI 0.39–0.75)]; third hour, 86–92% [HR 0.46 (95% CI 0.33–0.65)]. In about one-third of patients the RBV was within these ranges and in two-thirds it was above. Subgroup analysis by median age (≤/> 61 years), sex, race (white/nonwhite), predialysis systolic blood pressure (SBP; ≤/> 130 mmHg) and median interdialytic weight gain (≤/> 2.3 kg) showed comparable favorable RBV ranges. Patients with a 3-h RBV between 86 and 92% were younger, had higher ultrafiltration volumes and rates, similar intradialytic average and nadir SBPs and hypotension rates, lower postdialysis SBP and a lower prevalence of congestive heart failure when compared with patients with an RBV >92%. In the multivariate Cox analysis, RBV ranges remained independent and significant outcome predictors.

Conclusion

Specific hourly intradialytic RBV ranges are associated with lower all-cause mortality in chronic HD patients.

The effect of BCM guided dry weight assessment on short-term survival in Chinese hemodialysis patients : Primary results of a randomized trial - BOdy COmposition MOnitor (BOCOMO) study

BACKGROUND

Lack of accurate and effective assessment tools of fluid status is one of the major challenges to reach proper dry weight (DW) in chronic hemodialysis (HD) population. The aim of this randomized study was to evaluate the effect of bioimpedance guided DW assessment on long-term outcomes in Chinese HD patients. Eligible patients were randomly assigned (1:1) to two groups in each center, the control group and body composition monitor (BCM) group. In the BCM group, DW has been evaluated by bioimpedance technic every 2 months during follow-up. The primary composite endpoint consisted of death, acute myocardial infarction, cerebral infarction, cerebral hemorrhage, and peripheral vascular disease.

METHODS

A total of 445 patients were recruited from 11 hemodialysis centers from Beijing, Tianjin and Shijiazhuang cities from Jan 1, 2013 to Dec 31, 2014. They were randomized into either BCM group or control group. All patients have been followed up for 1 year or until Dec 31, 2014 or censoring.

RESULTS

At baseline, there were no significant differences between two groups in terms of demographic parameters, dialysis vintage, percentage of vascular access, and comorbid conditions. At the end of the study, 18 (4.04%) patients had died (11 in control group and 7 in BCM group). Kaplan-Meier survival analysis showed no significant difference in survival rates between two groups (log-rank test P = 0.07). However, there was an increasing trend of survival rates in BCM group compared to the control group. In the multivariable Cox analysis, there was a nonsignificant trend toward less primary composite end points in the BCM group in the adjusted analysis, the hazard ratio was impressive (0.487, 95% CI 0.217-1.091, P = 0.08).

CONCLUSION

Bioimpedance technic has been applied to assess fluid status for decades and has been proved to be a promising tool for clinical practice. Although short-term outcomes were not improved in the randomized, controlled trial, the ascending trend in survival has been observed. Further studies are needed to investigate the survival benefit of bioimpedance method in DW assessment in a larger sample with longer follow-up period.

TRIAL REGISTRATION

ClinicalTrials.org, NCT01509937. Registered 13 January 2012.

Fluid overload is associated with use of a higher number of antihypertensive drugs in hemodialysis patients

INTRODUCTION

Hypertension is multifactorial, highly prevalent in the hemodialysis (HD) population and its adequate control requires, in addition to adequate volume management, often the use of multiple antihypertensive drugs. We aimed to describe the use of antihypertensive agents in a group of HD patients and to evaluate the factors associated with the use of multiple classes (≥3) of antihypertensives.

METHODS

We analyzed the baseline data from the HDFit study. Clinically stable patients with HD vintage between 3 and 24 months without any severe mobility limitation were recruited from sites throughout southern Brazil. Fluid status was measured pre-dialysis with the Body Composition Monitor (BCM; Fresenius, Germany). Fluid overload (FO) was considered when the overhydration index (OH) was greater than 7% of extracellular water (OH/ECW > 7%) and overweight was defined as a body mass index (BMI) greater than 25 kg/m² . Prescriptions of antihypertensive drugs were obtained from participants' reports and medical records. Logistic regression was employed to determine factors associated with excessive use of antihypertensive medication (≥3 classes).

FINDINGS

Of 195 studied patients, 171 with complete data were included (70% male, 53 ± 15 years old, 57% of them with FO). Pre-dialysis systolic blood pressure (SBP) was 150 ± 24 mmHg and patients used a median of 2 (1-3) antihypertensive drugs. Vasodilators (20%) were of lowest prevalence, use of other classes varied from 40% to 53%. Sixty-two (36%) subjects used ≥3 classes and presented a higher prevalence of diabetes and FO, lower prevalence of overweight, and higher SBP. In a logistic regression model age, BMI <25 kg/m² , and OH/ECW > 7% were associated with excessive drug use.

DISCUSSION

More than one-third of participants used ≥3 classes of antihypertensive drugs, and it was associated with older age, BMI <25 kg/m² and FO. Strategies that better manage FO may aid better blood pressure control and avoid the use of multiple antihypertensive medications.

Hypervolemia-Induced Immune Disturbances Do Not Involve IL-1ß but IL-6 and IL-10 Activation in Haemodialysis Patients

Dysregulated fluid homeostasis is frequent in haemodialysis (HD) patients and is linked to inflammation which may be elicited by endotoxemia. The impact of hypervolemia on immune cells has not been studied in detail. Therefore, we analysed the hypervolemic activation of peripheral blood mononuclear cells (PBMCs) in HD with special focus on the NLRP3 inflammasome response. First, 45 HD were included in the observational study. Immune parameters including cell counts, caspase-1, oxidative stress, cytokine gene expression and serum analysis (IL-1ß, IL-6, IL-10) were all measured at two time points. Fluid status was evaluated by electrical bioimpedance vector analysis, defining hypervolemia (H) as >75 vector percentile. Then, 17 patients were classified as hypervolemic (H-HD), 19 as normovolemic (N-HD) and 9 failed to meet the inclusion criteria. Monocytes were elevated and lymphocytes were decreased by hypervolemia. NLRP3 inflammasome components, caspase-1 and IL-1ß expression were not statistically different between the two groups. Serum IL-6 levels were significantly elevated in H-HD. IL-10 mRNA transcripts were elevated by 2-fold in H-HD but were not efficiently translated. We conclude that the NLRP3 inflammasome is not activated by hypervolemia thus refuting the thesis that endotoxemia may be a main driver for inflammation in H-HD. Nevertheless, inflammation is generally higher in H-HD compared to N-HD patients and is not sufficiently balanced by anti-inflammatory mechanisms.

Seasonal and Secular Trends of Cardiovascular, Nutritional, and Inflammatory Markers in Patients on Hemodialysis

BACKGROUND

All life on earth has adapted to the effects of changing seasons. The general and ESKD populations exhibit seasonal rhythms in physiology and outcomes. The ESKD population also shows secular trends over calendar time that can convolute the influences of seasonal variations. We conducted an analysis that simultaneously considered both seasonality and calendar time to isolate these trends for cardiovascular, nutrition, and inflammation markers.

METHODS

We used data from adult patients on hemodialysis (HD) in the United States from 2010 through 2014. An additive model accounted for variations over both calendar time and time on dialysis. Calendar time trends were decomposed into seasonal and secular trends. Bootstrap procedures and likelihood ratio methods tested if seasonal and secular variations exist.

RESULTS

We analyzed data from 354,176 patients on HD at 2436 clinics. Patients were 59±15 years old, 57% were men, and 61% had diabetes. Isolated average secular trends showed decreases in pre-HD systolic BP (pre-SBP) of 2.6 mm Hg (95% CI, 2.4 to 2.8) and interdialytic weight gain (IDWG) of 0.35 kg (95% CI, 0.33 to 0.36) yet increases in post-HD weight of 2.76 kg (95% CI, 2.58 to 2.97). We found independent seasonal variations of 3.3 mm Hg (95% CI, 3.1 to 3.5) for pre-SBP, 0.19 kg (95% CI, 0.17 to 0.20) for IDWG, and 0.62 kg (95% CI, 0.46 to 0.79) for post-HD weight as well as 0.12 L (95% CI, 0.11 to 0.14) for ultrafiltration volume, 0.41 ml/kg per hour (95% CI, 0.37 to 0.45) for ultrafiltration rates, and 3.30 (95% CI, 2.90 to 3.77) hospital days per patient year, which were higher in winter versus summer.

CONCLUSIONS

Patients on HD show marked seasonal variability of key indicators. Secular trends indicate decreasing BP and IDWG and increasing post-HD weight. These methods will be of importance for independently determining seasonal and secular trends in future assessments of population health.

Anesthetic Considerations for Patients on Renal Replacement Therapy

The number of patients presenting for surgery with renal dysfunction requiring renal replacement therapy (RRT) is expected to increase as the population ages and improvements in therapy continue to be made. Every aspect of the perioperative period is affected by renal dysfunction, its associated comorbidities, and altered physiology secondary to RRT. Most alarming is the increased risk for perioperative cardiac morbidity and mortality seen in this population. Perioperative optimization and management aims to minimize these risks; however, few definite guidelines on how to do so exist.

Extracellular resistance is sensitive to tissue sodium status; implications for bioimpedance-derived fluid volume parameters in chronic kidney disease

Multifrequency bioimpedance spectroscopy (BIS) is an established method for assessing fluid status in chronic kidney disease (CKD). However, the technique is lacking in predictive value and accuracy. BIS algorithms assume constant tissue resistivity, which may vary with changing tissue ionic sodium concentration (Na+). This may introduce significant inaccuracies to BIS outputs. To investigate this, we used 23Na magnetic resonance imaging (MRI) to measure Na+ in muscle and subcutaneous tissues of 10 healthy controls (HC) and 20 patients with CKD 5 (not on dialysis). The extracellular (Re) and intracellular (Ri) resistance, tissue capacitance, extracellular (ECW) and total body water (TBW) were measured using BIS. Tissue water content was assessed using proton density-weighted MRI with fat suppression. BIS-derived volume indices were comparable in the two groups (OH: HC - 0.4 ± 0.9 L vs. CKD 0.5 ± 1.9 L, p = 0.13). However, CKD patients had higher Na+ (HC 21.2 ± 3.0, CKD 25.3 ± 7.4 mmol/L; p = 0.04) and significantly lower Re (HC 693 ± 93.6, CKD 609 ± 74.3 Ohms; p = 0.01); Ri and capacitance did not vary. Na+ showed a significant inverse linear relationship to Re (rs = - 0.598, p < 0.01) but not Ri. This relationship of Re (y) and Na+ (x) is described through equation y = - 7.39x + 814. A 20% increase in tissue ionic Na+ is likely to overestimate ECW by 1.2-2.4L. Tissue Na+ concentration has a significant inverse linear relationship to Re. BIS algorithms to account for this effect could improve prediction accuracy of bioimpedance derived fluid status in CKD.

Three compartment bioimpedance spectroscopy in the nutritional assessment and the outcome of patients with advanced or end stage kidney disease: What have we learned so far?

Bioimpedance spectroscopy (BIS) is an easily applicable tool to assess body composition. The three compartment model BIS (3C BIS) conventionally expresses body composition as lean tissue index (LTI) (lean tissue mass [LTM]/height in meters squared) and fat tissue index (FTI) (adipose tissue mass/height in meters squared), and a virtual compartment reflecting fluid overload (FO). It has been studied extensively in relation to diagnosis and treatment guidance of fluid status disorders in patients with advanced‐stage or end‐stage renal disease. It is the aim of this article to provide a narrative review on the relevance of 3C BIS in the nutritional assessment in this population. At a population level, LTI decreases after the start of hemodialysis, whereas FTI increases. LTI below the 10th percentile is a consistent predictor of outcome whereas a low FTI is predominantly associated with outcome when combined with a low LTI. Recent research also showed the connection between low LTI, inflammation, and FO, which are cumulatively associated with an increased mortality risk. However, studies toward nutritional interventions based on BIS data are still lacking in this population. In conclusion, 3C BIS, by disentangling the components of body mass index, has contributed to our understanding of the relevance of abnormalities in different body compartments in chronic kidney disease patients, and appears to be a valuable prognostic tool, at least at a population level. Studies assessing the effect of BIS guided nutritional intervention could further support its use in the daily clinical care for renal patients.

Sodium and water handling during hemodialysis: new pathophysiologic insights and management approaches for improving outcomes in end-stage kidney disease

Space medicine and new technology such as magnetic resonance imaging of tissue sodium stores (²³NaMRI) have changed our understanding of human sodium homeostasis and pathophysiology. It has become evident that body sodium comprises 3 main components. Two compartments have been traditionally recognized, namely one that is circulating and systemically active via its osmotic action, and one slowly exchangeable pool located in the bones. The third, recently described pool represents sodium stored in skin and muscle interstitium, and it is implicated in cell and biologic activities via local hypertonicity and sodium clearance mechanisms. This in-depth review provides a comprehensive view on the pathophysiology and existing knowledge gaps of systemic hemodynamic and tissue sodium accumulation in dialysis patients. Furthermore, we discuss how the combination of novel technologies to quantitate tissue salt accumulation (e.g., ²³NaMRI) with devices to facilitate the precise attainment of a prescribed hemodialytic sodium mass balance (e.g., sodium and water balancing modules) will improve our therapeutic approach to sodium management in dialysis patients. While prospective studies are required, we think that these new diagnostic and sodium balancing tools will enhance our ability to pursue more personalized therapeutic interventions on sodium and water management, with the eventual goal of improving dialysis patient outcomes.

Cardiovascular risk factors in children on dialysis: an update

Cardiovascular disease (CVD) is a life-limiting comorbidity in patients with chronic kidney disease (CKD). In childhood, imaging studies have demonstrated early phenotypic characteristics including increases in left ventricular mass, carotid artery intima-media thickness, and pulse wave velocity, which occur even in young children with early stages of CKD. Vascular calcifications are the signature of an advanced phenotype and are mainly found in adolescents and young adults treated with dialysis. Association studies have provided valuable information regarding the significance of a multitude of risk factors in promoting CVD in children with CKD by using intermediate endpoints of measurements of surrogate parameters of CVD. Dialysis aggravates pre-existing risk factors and accelerates the progression of CVD with additional dialysis-related risk factors. Coronary artery calcifications in children and young adults with CKD accumulate in a time-dependent manner on dialysis. Identification of risk factors has led to improved understanding of principal mechanisms of CKD-induced damage to the cardiovascular system. Treatment strategies include assessment and monitoring of individual risk factor load, optimization of treatment of modifiable risk factors, and intensified hemodialysis if early transplantation is not possible.

Early postoperative weight gain is associated with increased risk of graft failure in living donor liver transplant recipients

Fluid overload (FO) has been shown to adversely affect multiple organs and survival in critically ill patients. Liver transplantation (LT) carries the risk of massive transfusion, which frequently results in FO. We investigated the association of postoperative weight gain with graft failure, early allograft dysfunction (EAD), and overall mortality in LT. 1833 living donor LT (LDLT) recipients were retrospectively analysed. Patients were divided into 2 groups according to postoperative weight gain (<3% group [n = 1391] and ≥3% group [n = 442]) by using maximally selected log-rank statistics for graft failure. Multivariate Cox and logistic regression analyses were performed. The ≥3% group was associated with graft failure (adjusted HR [aHR], 1.763; 95% CI, 1.248–2.490; P = 0.001). When postoperative weight change was used as a continuous variable, the aHR for each 1% increase in postoperative weight was 1.045 (95% CI, 1.009–1.082; P = 0.015). In addition, the ≥3% group was associated with EAD (adjusted OR [aOR], 1.553; 95% CI, 1.024–2.356; P = 0.038) and overall mortality (aHR, 1.731; 95% CI, 1.182–2.535; P = 0.005). In conclusion, postoperative weight gain may be independently associated with increased risk of graft failure, EAD, and mortality in LDLT recipients.

Intradialytic Hypotension: Mechanisms and Outcome

Intradialytic hypotension (IDH) occurs in approximately 10-12% of treatments. Whereas several definitions for IDH are available, a nadir systolic blood pressure carries the strongest relation with outcome. Whereas the relation between IDH may partly be based on patient characteristics, it is likely that also impaired organ perfusion leading to permanent damage, plays a role in this relationship. The pathogenesis of IDH is multifactorial and is based on a combination of a decline in blood volume (BV) and impaired vascular resistance at a background of a reduced cardiovascular reserve. Measurements of absolute BV based on an on-line dilution method appear more promising than relative BV measurements in the prediction of IDH. Also, feedback treatments in which ultrafiltration rate is automatically adjusted based on changes in relative BV have not yet resulted in improvement. Frequent assessment of dry weight, attempting to reduce interdialytic weight gain and prescribing more frequent or longer dialysis treatments may aid in preventing IDH. The impaired vascular response can be improved using isothermic or cool dialysis treatment which has also been associated with a reduction in end organ damage, although their effect on mortality has not yet been assessed. For the future, identification of vulnerable patients based on artificial intelligence and on-line assessment of markers of organ perfusion may aid in individualizing treatment prescription, which will always remain dependent on the clinical context of the patient.

Using Bioimpedance Spectroscopy to Assess Volume Status in Dialysis Patients

The aim of the paper is to reflect on the current status of bioimpedance spectroscopy (BIS) in fluid management in dialysis patients. BIS identifies fluid overload (FO) as a virtual (overhydration) compartment, which is calculated from the difference between the measured extracellular volume and the predicted values based on a fixed hydration of lean and adipose tissue mass. FO is highly prevalent in both hemodialysis (HD) and peritoneal dialysis (PD) patients, while levels of FO are at a population level comparable between PD patients and HD patients when measured before the dialysis treatment. Even mild levels of FO are independently related to outcome in patients on HD, PD as well as in nondialysis patients with advanced chronic kidney disease. FO is not only related to left ventricular hypertrophy (LVH) but also forms part of a multidimensional spectrum with noncardiovascular risk factors such as malnutrition and inflammation. Even after multiple adjustments, FO remains an independent predictor of mortality. BIS-assisted adjustment of dry weight in HD patients has been shown to improve hypertension control and LVH and has resulted in a decline in intradialytic symptomatology. On the other hand, with increased fluid removal, target weight may not always be reached due to an increase in intradialytic symptomatology, and care should be applied in target weight adjustment in fluid overloaded patients with severe malnutrition and/or inflammation. Although a reduction in hospitalization rate was suggested, the effect of BIS-guided dry weight adjustment on mortality has not yet been shown, however, although available studies are underpowered. In PD patients, results have been more equivocal, which may be partly related to differences in treatment protocols or study populations. Future large-scale studies are needed to assess the full potential of BIS.

Survival comparison between superficialization of the brachial artery and tunneled central venous catheter placement in hemodialysis patients with heart failure: A retrospective study

It remains unclear which vascular access provides better survival in hemodialysis patients with heart failure, superficialization of the brachial artery (SBA), or tunneled central venous catheter (TCVC). We retrospectively followed up 60 hemodialysis patients with heart failure who underwent SBA (n = 36) or TCVC placement (n = 24). During the median 2.2-year follow-up period, 36 patients died. The median survival time was significantly longer for the SBA group than for the TCVC group (5.7 vs 1.7 years; P < .05, log-rank test). A multivariate-adjusted Cox regression analysis showed that SBA was associated with a reduced risk of all-cause death (hazard ratio [HR] 0.30; 95% confidence interval [CI] 0.14-0.65). In the cohort of propensity score-matched 15 pairs, patients with SBA experienced fewer all-cause deaths (HR 0.29; 95% CI 0.10-0.77). Our study suggests that SBA is an alternative option in hemodialysis patients with heart failure.

Systematic Fluid Assessment in Haemodialysis: Development and Validation of A Decision Aid

BACKGROUND

About a third of patients undergoing haemodialysis have poorly controlled fluid status, which may affect survival. Clinical assessment is subjective and imprecise, which has led to the increasing use of devices based on bioimpedance spectroscopy (BIS). However, BIS cannot provide a simple target applicable to all patients. Our aim was to develop and validate a decision aid combining clinical assessment of fluid status with information from BIS in target weight determination.

METHODS

The decision aid was based on empirical experience and a literature review identifying physiological parameters already used in the clinical assessment of fluid status. Content validity was established by patient representatives, interdisciplinary stakeholders and external experts, who assessed item relevance and comprehensiveness. Reliability was assessed by inter-rater agreement analysis between nurses assessing typical patient cases.

RESULTS

The decision aid for Recognition and Correction of Volume Alterations (RECOVA) consists of three parts (1) a scoring system; (2) thresholds and triggers; (3) a decision aid algorithm. Agreement between raters in the assessment of symptoms was almost perfect, with Intraclass Correlation Coefficient > 0.90. Agreement in clinical response was only fair, but increased to moderate, with training and self-reported confidence.

CONCLUSION

RECOVA may enable systematic clinical assessment of fluid status, facilitating early recognition of fluid alterations, and incorporation of bioimpedance into target weight management. However, implementation into clinical practice will require training of staff. Clinical intervention studies are required to evaluate if RECOVA facilitates response to and correction of recognised fluid alterations.

Impact of Periodontal Inflammation on Nutrition and Inflammation Markers in Hemodialysis Patients

Background: Malnutrition-inflammation complex syndrome (MICS) is a common and usually concurrent condition occurring in patients undergoing hemodialysis (HD), with a pathogenesis linked to biological and in situ environmental traditional risk factors. Periodontitis, one of the major types of infection-driven inflammation, often co-occurs in the in the hemodialysis population and correlates with markers of malnutrition and inflammation, such as albumin, creatinine, and C-reactive protein. Aim: The present study aimed to determine whether the periodontal inflammatory status parameters correlate with the albumin, creatinine, and C-reactive protein serum concentrations in HD patients, and investigate whether periodontal treatment improves these markers of nutritional and systemic inflammation. Materials and Methods: The serum creatinine, albumin, and C-reactive Protein (CRP) levels were measured at baseline and after non-surgical periodontal treatment, at 3 months and 6 months. Results: At 3 months, a significant correlation between plaque index and C-reactive protein (p = 0.012), bleeding on probing and C-reactive protein (p < 0.0019), and clinical attachment level and C-reactive protein (p = 0.022) was found. No significant correlation was found between clinical periodontal parameters and nutrition markers at each time. Conclusions: Our results confirmed the association between C-reactive protein serum concentration and periodontal inflammatory status, but further research is necessary to identify the contributing role of periodontitis on the onset and progression of MICS.

Greater fluid overload and lower interdialytic weight gain are independently associated with mortality in a large international hemodialysis population

Background

Fluid overload and interdialytic weight gain (IDWG) are discrete components of the dynamic fluid balance in haemodialysis patients. We aimed to disentangle their relationship, and the prognostic importance of two clinically distinct, bioimpedance spectroscopy (BIS)-derived measures, pre-dialysis and post-dialysis fluid overload (FOpre and FOpost) versus IDWG.

Methods

We conducted a retrospective cohort study on 38 614 incident patients with one or more BIS measurement within 90 days of haemodialysis initiation (1 October 2010 through 28 February 2015). We used fractional polynomial regression to determine the association pattern between FOpre, FOpost and IDWG, and multivariate adjusted Cox models with FO and/or IDWG as longitudinal and time-varying predictors to determine all-cause mortality risk.

Results

In analyses using 1-month averages, patients in quartiles 3 and 4 (Q3 and Q4) of FO had an incrementally higher adjusted mortality risk compared with reference Q2, and patients in Q1 of IDWG had higher adjusted mortality compared with Q2. The highest adjusted mortality risk was observed for patients in Q4 of FOpre combined with Q1 of IDWG [hazard ratio (HR) = 2.66 (95% confidence interval 2.21-3.20), compared with FOpre-Q2/IDWG-Q2 (reference)]. Using longitudinal means of FO and IDWG only slightly altered all HRs. IDWG associated positively with FOpre, but negatively with FOpost, suggesting a link with post-dialysis extracellular volume depletion.

Conclusions

FOpre and FOpost were consistently positive risk factors for mortality. Low IDWG was associated with short-term mortality, suggesting perhaps an effect of protein-energy wasting. FOpost reflected the volume status without IDWG, which implies that this fluid marker is clinically most intuitive and may be best suited to guide volume management in haemodialysis patients.

Pre-dialysis fluid status, pre-dialysis systolic blood pressure and outcome in prevalent haemodialysis patients: results of an international cohort study on behalf of the MONDO initiative

Background

Pre-dialysis fluid overload (FO) associates with mortality and causes elevated pre-dialysis systolic blood pressure (pre-SBP). However, low pre-SBP is associated with increased mortality in haemodialysis patients. The objective of this study was to investigate the interaction between pre-dialysis fluid status (FS) and pre-SBP in association with mortality.

Methods

We included all patients from the international Monitoring Dialysis Outcome Initiative (MONDO) database with a pre-dialysis multifrequency bioimpedance spectroscopy measurement in the year 2011. We used all parameters available during a 90-day baseline period. All-cause mortality was recorded during 1-year follow-up. Associations with outcome were assessed with Cox models and a smoothing spline Cox analysis.

Results

We included 8883 patients. In patients with pre-dialysis FO (>+1.1 to +2.5 L), pre-SBP <110 mmHg was associated with an increased risk of death {hazard ratio (HR) 1.52 [95% confidence interval (CI) 1.06-2.17]}. An increased risk of death was also associated with pre-dialysis fluid depletion (FD; <-1.1 L) combined with a pre-SBP <140 mmHg. In normovolemic (NV) patients, low pre-SBP <110 mmHg was associated with better survival [HR 0.46 (95% CI 0.23-0.91)]. Also, post-dialysis FD associated with a survival benefit. Results were similar when inflammation was present. Only high ultrafiltration rate could not explain the higher mortality rates observed.

Conclusion

The relation between pre-SBP and outcome is dependent on pre-dialysis FS. Low pre-SBP appears to be disadvantageous in patients with FO or FD, but not in NV patients. Post-dialysis FD was found to associate with improved survival. Therefore, we suggest interpreting pre-SBP levels in the context of FS and not as an isolated marker.

The Effects of Melatonin Supplementation on Parameters of Mental Health, Glycemic Control, Markers of Cardiometabolic Risk, and Oxidative Stress in Diabetic Hemodialysis Patients: A Randomized, Double-Blind, Placebo-Controlled Trial

OBJECTIVE

This study evaluated the effects of melatonin supplementation on parameters of mental health, glycemic control, markers of cardiometabolic risk, and oxidative stress in diabetic hemodialysis (HD) patients.

DESIGN

A randomized, double-blind, placebo-controlled clinical trial was conducted in 60 diabetic HD patients, 18-80 years of age. Participants were randomly divided into 2 groups to take either melatonin (2 x 5mg/day) (n = 30) or placebo (n = 30) 1 hour before bedtime for 12 weeks. The effects of melatonin on mental health, metabolic status, and gene expression related to metabolic status were assessed using multiple linear regression adjusting for age and BMI.

RESULTS

Melatonin supplementation significantly decreased Pittsburgh Sleep Quality Index (P = .007), Beck Depression Inventory index (P = .001), and Beck Anxiety Inventory index (P = .01) compared with the placebo. Additionally, melatonin administration significantly reduced fasting plasma glucose (β = -21.77 mg/dL, 95% CI -33.22 to -10.33, P < .001), serum insulin levels (β = -1.89 μIU/mL, 95% CI -3.34 to -0.45, P = .01), and homeostasis model of assessment-insulin resistance (β = -1.45, 95% CI -2.10 to -0.80, P < .001), and significantly increased the quantitative insulin sensitivity check index (β = 0.01, 95% CI 0.007-0.02, P < .001) compared with placebo treated subjects. In addition, melatonin administration resulted in a significant reduction in serum high sensitivity C-reactive protein (β = -1.92 mg/L, 95% CI -3.02 to -0.83, P = .001) and plasma malondialdehyde (β = -0.21 μmol/L, 95% CI -0.36 to -0.06, P = .005); also, significant rises in plasma total antioxidant capacity (β = 253.87 mmol/L, 95% CI 189.18-318.56, P < .001) and nitric oxide levels (β = 2.99 μmol/L, 95% CI 0.71-5.28, P = .01) were observed compared with the placebo.

CONCLUSION

Overall, melatonin supplementation for 12 weeks to diabetic HD patients had beneficial effects on mental health, glycemic control, inflammatory markers, and oxidative stress.

Meta-Analysis of Randomized Controlled Trials Using Tool-Assisted Target Weight Adjustments in Chronic Dialysis Patients

INTRODUCTION

Technological adjuncts have been developed to improve the accuracy of fluid removal goals in maintenance dialysis recipients. We aimed to determine whether the introduction of these tools has been shown to impact clinical outcomes.

METHODS

We performed a systematic review and meta-analysis of randomized controlled trials that compared fluid management guided by technological adjuncts to standard care in hemodialysis and peritoneal dialysis. The primary outcome was all-cause mortality. Secondary outcomes were cardiovascular events, hospitalizations, intradialytic hypotension, blood pressure, symptoms, antihypertensive medications. and left ventricular mass index.

RESULTS

Of the 2940 citations retrieved, we identified a total of 12 eligible trials comprising 2406 participants. In the 10 studies (n = 2111) with data on mortality, the use of adjunct technologies was not associated with a reduction of mortality (rate ratio [RR]: 0.92; confidence interval [CI]: 0.57-1.51; I2 = 36%). The intervention conferred a reduction in systolic arterial pressure (mean difference: -3.14; CI: -5.89 to -0.38; I2 = 39%) but did not affect other outcomes. In a subgroup analysis, bioimpedance was associated with a reduced risk of hospitalization (RR: 0.68; CI: 0.46-0.99; I2 = 55%). The risk of bias was high or unclear in most studies and the quality of evidence was judged to be low.

CONCLUSIONS

Among maintenance dialysis recipients, technological adjuncts for fluid management did not improve survival. Trials mostly investigated the use of bioimpedance, whereas the evidence for use of other technologies remain very scarce. Future adequately powered trials should assess a broader array of promising technologies using meaningful clinical outcomes over a prolonged follow-up duration.

Time to Reconsider the Role of Relative Blood Volume Monitoring for Fluid Management in Hemodialysis

Relative blood volume (RBV) monitoring during hemodialysis has been used to help guide fluid management for decades, although with little supporting evidence. The technique relies on the assumption that variation in RBV during fluid removal reflects the capacity for vascular refilling and that efficient refilling is related to fluid overload. This study investigated the relationship between RBV variation and bioimpedance-based fluid overload in 47 patients on stable hemodialysis. Mean treatment ultrafiltration volume (UFV) was 1.7 L and RBV reduction was 3.2%/hour. Relative blood volume slopes were grouped based on trajectory: flatline (no decrease), linear decrease, or linear decrease followed by flatline. Fluid overload was similar (p > 0.05) across groups pre-dialysis (1.0, 2.2, and 1.6 L, respectively) and post-dialysis (-0.8, -0.1, and -0.1 L), whereas UFV was higher in patients with a linear decrease (1.8, 2.5, and 1.6 L; p = 0.02). Specific ultrafiltration rate, but not fluid overload, was associated with RBV change over dialysis. At least half the patients in each group finished dialysis fluid depleted based on bioimpedance, suggesting that the link between refilling and fluid overload is not as straightforward as previously assumed. These results question the assumptions that the absence of an appreciable decrease in RBV indicates fluid overload, and a rapid fall suggests fluid depletion.

Extracellular fluid volume is associated with incident end-stage kidney disease and mortality in patients with chronic kidney disease

Volume overload has been shown to be an independent risk factor for mortality in patients receiving chronic dialysis, but data in non-dialysis patients are scarce. Therefore we evaluated the prognostic value of extracellular fluid (ECF) volume for chronic kidney disease (CKD) progression and mortality in a prospective hospital-based cohort with CKD stage 1-4 (NephroTest Study). ECF (scaled to body surface area) and the measured glomerular filtration rate (mGFR) were determined using the distribution volume and clearance of 51Cr-EDTA, respectively. Cause-specific Cox and linear mixed-effect regression models were used to analyze the association of ECF with end-stage kidney disease (ESKD) and mortality, and with mGFR decline, respectively. The 1593 patients were mean age 58.8 years, 67% were men, mean mGFR of 43.6 mL/min/1.73m² and mean ECF 15.1 L/1.73m². After a median follow-up of 5.3 years, ESKD occurred in 324 patients and 185 patients died before ESKD. In multivariable analysis, ECF was significantly associated with the risk of ESKD (hazard ratio per 1L/1.73m² increase: 1.14; 95% confidence interval [1.07; 1.21]) and with a faster GFR decline (adjusted mean difference in mGFR slope per 1L/1.73m² increase -0.14 [-0.23; -0.05] mL/min/year). The relationship of ECF with mortality was non-linear and not significant (per 1L/1.73m² increase 0.92, [0.73; 1.16]), below 15L/1.73m², but significant (1.28; [1.14-1.45]) above 15L/1.73m². Thus, in this large cohort of carefully phenotyped patients with CKD, ECF was an independent risk factor of CKD progression and mortality. Hence, close monitoring and treatment of fluid overload are important for the clinical management of patients with non-dialysis CKD.

Point-of-care ultrasound in end-stage kidney disease: beyond lung ultrasound

PURPOSE OF REVIEW

Following the miniaturization of ultrasound devices, point-of-care ultrasound (POCUS) has been proposed as a tool to enhance the value of physical examination in various clinical settings. The objective of this review is to describe the potential applications of POCUS in end-stage renal disease patients (ESRD).

RECENT FINDINGS

With basic training, the clinician can perform pulmonary, vascular, cardiac, and abdominal POCUS at the bedside of ESRD patients. Pulmonary ultrasound can be used to quantify pulmonary congestion and for the differential diagnosis of dyspnea. Ultrasound of the inferior vena cava combined with simple cardiac ultrasound can be used to promptly investigate the mechanism of hemodynamic instability. Vascular ultrasound can be used for troubleshooting of arteriovenous fistula problems and for catheter installation. Multiple potential applications of POCUS in the ESRD population are reviewed, including areas of future research.

SUMMARY

Acquiring basic skills in POCUS may improve patient care through the rapid identification of threats, improved diagnostic abilities for common symptoms, and safer procedures. The adoption of POCUS in undergraduate, internal medicine and nephrology training curriculums will likely lead to a gradual introduction of this technology in the care of ESRD patients.

The use of bioimpedance spectroscopy to guide fluid management in patients receiving dialysis

PURPOSE OF REVIEW

To summarize the findings of recent trials and meta-analyses designed to determine whether bioimpedance spectroscopy adds value to the clinical assessment of fluid status in dialysis patients so as to achieve a normally hydrated weight and put these in a contemporary context.

RECENT FINDINGS

Eight trials (published 2010-2018) and two meta-analyses (2017) are reviewed. Both haemodialysis and peritoneal dialysis modalities are represented. Despite considerable heterogeneity in intervention, all are open-label randomized comparisons of a bioimpedance intervention with normal clinical practice in which clinicians were blinded to bioimpedance data. In a total of 1443 patients studied, no significant differences in mortality, cardiovascular or adverse events between groups were observed. Bioimpedance use was associated with a reduction in overhydration, especially when residual kidney function was not present and a greater reduction in blood pressure. A modest correlation in the change in fluid status and fall in systolic blood pressure was seen compared to baseline. A more rapid fall in urine volume was seen in the two studies with the greatest change in fluid status, with significantly higher risk of anuria in one. How bioimpedance was integrated with the complex process of decision making by clinicians was variable and not always explained.

SUMMARY

The usefulness of bioimpedance spectroscopy in guiding fluid management in dialysis patients is not yet clear. Bioimpedance can drive clinical decisions that lead to significant changes in fluid status but the best way to apply this in clinical practice requires further studies.