On the importance of pedal edema in hemodialysis patients

Use of lung ultrasound to assess volume status and its association with physical examination in patients with chronic kidney disease

Introduction

Defining the optimal hydration status in patients with chronic kidney disease (CKD) is challenging, and the quest for an objective accurate method continues. Lung ultrasound (LUS) is a well-validated technique to estimate volume status. Previous studies examining the relationship between LUS and physical examination demonstrated conflicting results. We aimed to evaluate the correlation between LUS results and physical examination for assessing volume status in patients with CKD, and to compare different LUS protocols.

Methods

A prospective, single-center trial correlating physical examination findings to LUS results in different CKD groups, including non-dialysis and dialysis patients. Hemodialysis patients were tested twice, before and after dialysis, to compare results with ultrafiltration volume. Different LUS protocols were performed and compared, including 16-, 12-, and 8-zone measurements.

Results

We recruited 175 participants. A strong positive correlation was demonstrated between 16- and 12-zone protocols [r = .91 (P < .001)] and between 12- and 8-zone protocols (r = .951, P < .001). Correlation was significant in various CKD groups. While blood pressure did not correlate with LUS score, there was a significant correlation between LUS and other components of the physical examination including lung crackles (OR = 1.15 (95%CI 1.096-1.22), P < .01), pleural effusion (OR = 1.15 (95%CI 1.09-2.13), P < .01) and peripheral edema (r = .24, P < .001). Ultrafiltration volume did not correlate significantly with change in LUS scores pre- and post-dialysis (r = .169, P = .065).

Conclusion

Most components of physical examination findings correlated with extravascular lung water assessment on LUS in CKD patients. The use of a simplified pragmatic LUS protocol may facilitate LUS use in clinical practice.

Extracellular fluid excess linked to reduced choroidal vascularity index in patients with chronic kidney disease

Extracellular fluid (ECF) excess is common in patients with chronic kidney disease (CKD). This study (involving 284 patients with CKD) explored the association between choroidal vascularity index (CVI) and ECF excess. We categorised patients into three groups based on extracellular water/total body water: normal, mildly overhydrated, and severely overhydrated. The more severe ECF status was associated with a lower CVI after adjustment (B = - 0.902, p = 0.001). In non-diabetic patients, both vascular luminal (LA, p < 0.001) and stromal areas (SA, p = 0.003) were significantly reduced in patients with severe ECF excess compared to others, whereas diabetic patients showed no significant differences in LA (p = 0.96) and SA (p = 0.86) based on ECF excess status. These findings suggest that ECF status may influence CVI in patients with CKD, underscoring the need for further research to clarify its direct impact on choroidal changes.

The superiority of bioimpedance vs. echocardiography and pitting edema in predicting automated office blood pressure in continuous ambulatory peritoneal dialysis patients

INTRODUCTION

To achieve optimal blood pressure control in continuous ambulatory peritoneal dialysis (CAPD) patients, identifying methods of volume assessment with the strongest correlation with blood pressure is essential.

METHODS

In this cross-sectional study, 52 CAPD patients were assigned to automated office blood pressure (AOBP) measurement, assessment of pedal pitting edema, bioimpedance analysis (BIA), and inferior vena cava collapsibility index (IVCCI%) measurement. Data were analyzed using STATA ver.17, and the significance level was p < 0.05.

RESULTS

Fifty-two patients were divided based on their AOBP readings. 29 (55.8%) of patients had uncontrolled AOBP. Overhydration (OH) and the grade of pitting edema were significantly higher in the uncontrolled AOBP group. OH was identified as the best variable for predicting blood pressure (p ≤ 0.001) and detecting uncontrolled blood pressure (AUC = 0.832) using multivariate linear regression and ROC analysis, respectively.

CONCLUSION

BIA-derived OH was the best variable for predicting systolic and diastolic AOBP, outperforming IVCCI% and pitting edema.

On Whether Ca-125 Is the Answer for Diagnosing Overhydration, Particularly in End-Stage Kidney Disease Patients-A Systematic Review

Overhydration (OH) is a prevalent medical problem that occurs in patients with kidney failure, but a specific marker has still not been found. Patients requiring kidney replacement therapy suffer from a water imbalance, which is correlated with mortality rates in this population. Currently, clinicians employ techniques such as bioimpedance spectroscopy (BIS) and ultrasound (USG) markers of overhydration or markers of heart and kidney function, namely NT-pro-BNP, GFR, or creatinine levels. New serum markers, including but not limited to Ca-125, galectin-3 (Gal-3), adrenomedullin (AMD), and urocortin-2 (UCN-2), are presently under research and have displayed promising results. Ca-125, which is a protein mainly used in ovarian cancer diagnoses, holds great potential to become an OH marker. It is currently being investigated by cardiologists as it corresponds to the volume status in heart failure (HF) and ventricular hypertrophy, which are also associated with OH. The need to ascertain a more precise marker of overhydration is urgent mainly because physical examinations are exceptionally inaccurate. The signs and symptoms of overhydration, such as edema or a gradual increase in body mass, are not always present, notably in patients with chronic kidney disease. Metabolic disruptions and cachexia can give a false picture of the hydration status. This review paper summarizes the existing knowledge on the assessment of a patient's hydration status, focusing specifically on kidney diseases and the role of Ca-125.

Simplified discriminant parameters for sarcopenia among patients undergoing haemodialysis

BACKGROUND

Patients with end-stage renal disease (ESRD) are at an increased risk of developing sarcopenia, which can lead to various adverse health outcomes. Although the diagnosis of sarcopenia is essential for clinical management, it is not feasible in routine clinical practice for populations undergoing haemodialysis because it is time-consuming and resources are limited. Serum creatinine levels in patients with ESRD have been gaining attention as a screening parameter for sarcopenia because serum creatinine is a routinely measured byproduct of skeletal muscle metabolism. This study aimed to evaluate the discriminative ability of the creatinine-derived index for sarcopenia in patients undergoing haemodialysis.

METHODS

We diagnosed sarcopenia according to the Asian Working Group for Sarcopenia (AWGS) 2 criteria in 356 clinically stable outpatients with ESRD enrolled from three dialysis facilities. We adopted the modified creatinine index as a simplified discriminant parameter for sarcopenia in addition to the calf circumference, SARC-F score, and combination of both (i.e. SARC-CalF score), which are recommended by the AWGS. Receiver operating characteristic analysis and logistic regression analysis were conducted to evaluate the discriminative ability of the modified creatinine index for sarcopenia.

RESULTS

Of the study participants, 142 (39.9%) were diagnosed with sarcopenia. The areas under the curve of the modified creatinine index against sarcopenia in the male and female participants were 0.77 (95% confidence interval [CI]: 0.71 to 0.83) and 0.77 (95% CI: 0.69 to 0.85), respectively. All simplified discriminant parameters were significantly associated with sarcopenia, even after adjusting for patient characteristics and centre. In the comparison of the odds ratios for sarcopenia for 1-standard deviation change in the simplified discriminant parameters, the odds ratio of the modified creatinine index was 1.92 (95% CI: 1.15 to 3.19), which was lower than that of the calf circumference (odds ratio: 6.58, 95% CI: 3.32 to 13.0) and similar to that of the SARC-F (odds ratio: 1.57, 95% CI: 1.14 to 2.16) and SARC-CalF scores (odds ratio: 2.36, 95% CI: 1.60 to 3.47).

CONCLUSIONS

This study revealed a strong association between the creatinine-derived index and sarcopenia in patients undergoing haemodialysis. The modified creatinine index was equal or superior to those of SARC-F and SARC-CalF score in discriminability for sarcopenia. However, the ability of the calf circumference to discriminate sarcopenia is extremely high, and further study is needed to determine whether it can be used to detect deterioration of muscle mass and function over time.

Bioelectrical impedance analysis versus physician adjustment in acute kidney injury patients to reduce intradialytic hypotension: A randomized controlled trial

Introduction

Methods

Result

Conclusion

•

Intradialytic hypotension is common during hemodialysis.

•

Bioimpedance spectroscopy can help assess fluid status in critically ill patients.

•

BIA-guided protocol can reduce significantly the incidence of IDH compared to conventional method.

This study aimed to evaluate IPC and NMES in haemodialysis patients with lower limb oedema. As a secondary objective, it also set out to evaluate the impact of localised fluid (oedema) on BCM measured fluid status

BACKGROUND

The presence of localised oedema can make measurement and removal of excess fluid in haemodialysis challenging.

OBJECTIVES

To evaluate (i) the effectiveness of intermittent pneumatic compression and neuromuscular electrical stimulation at mobilising oedema and (ii) the impact of localised fluid on bioimpedance measured fluid status.

DESIGN

A single centre, cross-over study design. Participants were monitored weekly during mid-week dialysis sessions. Four sessions with each of the interventions and no interventions, with washout periods between, were included.

PARTICIPANTS

Six participants with lower limb oedema and established on haemodialysis for at least 3 months.

MEASUREMENTS

The effectiveness of mobilising oedema and improving haemodynamic stability was assessed by: reduction in ankle circumference; ultrafiltration volume achieved; blood pressure changes; participant symptoms and achievement of target weight. The impact of localised fluid on bioimpedance measurements was assessed by comparing measurements across affected tissue with measurements avoiding the site of oedema.

RESULTS

There were no differences in ultrafiltration volumes, achievement of target weight, participant symptoms or reductions in ankle circumference and systolic blood pressure between intermittent pneumatic compression and neuromuscular electrical stimulation sessions compared to control sessions. Measurements of fluid overload with bioimpedance were 1.7 and 1.8 L higher when measuring across oedematous tissue compared to non-oedematous tissue.

CONCLUSIONS

We were unable to demonstrate improved mobilisation of fluid in the participant's lower limb, though there was a low number of study participants and notable interindividual variation observed. Bioimpedance offers potential for monitoring fluid management in individuals with lower limb oedema but specific protocols are necessary.

Lung Ultrasound as a Tool to Evaluate Fluid Accumulation in Dialysis Patients

BACKGROUND

Volume overload is the main mechanism of BP elevation in end-stage kidney disease (ESKD) patients undergoing hemodialysis or peritoneal dialysis and has been linked to adverse outcomes and increased mortality in this population.

SUMMARY

This review discusses current knowledge on lung ultrasound as a tool for detection of extracellular volume overload through evaluation of extravascular lung water content. We describe the principles of lung US, the main protocols to apply it in clinical practice, and accumulated data evidence regarding its associations with cardiovascular events and mortality. We also summarize available evidence on the effect of lung ultrasound-guided -volume management strategies on BP control, echocardiographic parameters, and major outcomes in patients undergoing dialysis.

KEY MESSAGES

Among interventions attempting to reduce the burden of cardiovascular disease in ESKD, effective management of volume overload represents an unmet clinical need. Assessment of hydration status by lung ultrasound is a cheap, easy to employ, and real-time technique that can offer accurate dry weight assessment leading to several clinical benefits.

Quantitative Lung Ultrasonography for the Nephrologist: Applications in Dialysis and Heart Failure

Volume overload, and its attendant increase in acute care utilization and cardiovascular morbidity and mortality, represents a critical challenge for the practicing nephrologist. This is particularly true among patients with ESKD on HD, where predialysis volume overload and intradialytic and postdialytic hypovolemia account for almost a third of all cost for the Medicare dialysis benefit. Quantitative lung ultrasound is a tool for assessing the extent of extravascular lung water that outperforms physical exam and plain chest radiography. B-lines are vertical hyperechoic artifacts present in patients with increased extravascular lung water. B-lines have been shown to decrease dynamically during the hemodialysis treatment in proportion to ultrafiltration volume. Among patients with chronic heart failure, titration of diuretics on the basis of the extent of pulmonary congestion noted on lung ultrasonography has been shown to decrease recurrent acute care utilization. Early data from randomized controlled trials of lung ultrasound-guided ultrafiltration therapy among patients with ESKD on HD have shown promise for potential reduction in recurrent episodes of decompensated heart failure and cardiovascular events. Ultimately, lung ultrasound may predict those who are ultrafiltration tolerant and could be used to decrease acute care utilization and, thus, cost in this population.

Protocol of a pilot-scale, single-arm, observational study to assess the utility and acceptability of a wearable hydration monitor in haemodialysis patients

Background

Fluid overload has a high prevalence in haemodialysis patients and is an important risk factor for excess mortality and hospitalisations. Despite the risks associated with chronic fluid overload, it is clinically difficult to assess and maintain fluid status adequately. Current methods of fluid status assessment are either imprecise or time intensive. In particular, to date, no method exists to accurately assess fluid status during the interdialytic interval.

Objectives

This pilot study aimed to evaluate whether a prototype wearable hydration monitor can accurately and reproducibly detect fluid overload in the haemodialysis population when compared to haemodialysis and bioimpedance data.

Methods

A prospective, open-label, single-arm observational trial of 20 patients commenced in January 2021 in a single haemodialysis centre in Ireland, with a wearable hydration monitor, the Sixty device. The Sixty device uses diffuse reflectance spectroscopy to measure fluid levels at the level of the subdermis and uses machine learning to develop an algorithm that can determine fluid status. The Sixty device was worn at every dialysis session and nocturnally over a three-week observational period. Haemodialysis parameters including interdialytic weight gain, ultrafiltration volume, blood pressure, and relative blood volume were collected from each session, and bioimpedance measurements using the Fresenius body composition monitor were performed on 4 occasions as a comparator. The primary objective of this trial was to determine the accuracy and reproducibility of the Sixty device compared to bioimpedance measurements.

Conclusion

If the accuracy of the wearable hydration monitor is validated, further studies will be conducted to integrate the device output into a multi-parameter machine learning algorithm that can provide patients with actionable insights to manage fluid overload in the interdialytic period.

Trial registration

www.clinicaltrials.govNCT04623281. Registered November 10th, 2020.

Integrative Volume Status Assessment

Volume status assessment is a critical but challenging clinical skill and is especially important for the management of patients in the emergency department, intensive care unit, and dialysis unit where accurate intravascular assessment is necessary to guide appropriate fluid management. Assessment of volume status is subjective and can vary from provider to provider, posing clinical dilemmas. Traditional non-invasive methods of volume assessment include assessment of skin turgor, axillary sweat, peripheral edema, pulmonary crackles, orthostatic vital signs, and jugular venous distension. Invasive assessments of volume status include direct measurement of central venous pressure and pulmonary artery pressures. Each of these has their own limitations, challenges, and pitfalls and were often validated based on small cohorts with questionable comparators. In the past 30 years, the increased availability, progressive miniaturization, and falling price of ultrasound devices has made point of care ultrasound (POCUS) widely available. Emerging evidence base and increased uptake across multiple subspecialities has facilitated the adoption of this technology. POCUS is now widely available, relatively inexpensive, free of ionizing radiation, and can help providers make medical decisions with more precision. POCUS is not intended to replace the physical exam, but rather to complement clinical assessment, guiding providers to give thorough and accurate clinical care to their patients. We should be mindful of the nascent literature supporting the use of POCUS and other limitations as uptake increases among providers and be wary not to use POCUS to substitute clinical judgement, but integrate ultrasonographic findings carefully with history and clinical examination.

High ultrafiltration rate induced intradialytic hypotension is a predictor for cardiac remodeling: a 5-year cohort study

BACKGROUND

Intradialytic-hypotension (IDH) is a common complication of hemodialysis. High ultrafiltration rate (UFR) might lead to IDH. However, the relationships between UFR, IDH, and cardiac remodeling among hemodialysis patients in the long-term have not been deeply explored.

METHODS

This retrospective cohort study collected clinical and echocardiographic data. Patients were enrolled from 1 January 2014 to 31 March 2014 and were followed-up for 5-year. Those who suffered from more than four hypotensive events during three months (10% of dialysis treatments) were defined as the IDH group. Subgroup analysis was done according to the UFR of 10 ml/h/kg. Associations between UFR, IDH, and alterations of cardiac structure/function were analyzed.

RESULTS

Among 209 patients, 96 were identified with IDH (45.9%). The survival rate of IDH patients was lower than that of no-IDH patients (65.5% vs. 81.4%, p = .005). In IDH group, decreased ejection fraction (EF), larger left atrium diameter index (LADI), and left ventricular mass index (LVMI) (p < .05) were observed at the end of the follow-up. In multivariate logistic model, the interaction between UFR and IDH was notably associated with LVMI variation (OR = 1.37). After adjusting covariates, UFR was still an independent risk factor of LVMI variation (OR = 1.52) in IDH group. In subsequent analysis, we divided patients according to UFR 10 ml/h/kg. For IDH-prone patients, decreased EF, larger LADI, and LVMI (p < .05) were observed at the end of the study only in high-UFR group.

CONCLUSIONS

UFR and IDH have interactions on cardiac remodeling. High ultrafiltration rate induced IDH is a predictor for cardiac remodeling in long-term follow-up.

Chronic Kidney Disease and Heart Failure-Everyday Diagnostic Challenges

Is advanced chronic kidney disease (CKD) a cardiac “no man’s land”? Chronic heart failure (HF) is widely believed to be one of the most serious medical challenges of the 21st century. Moreover, the number of patients with CKD is increasing. To date, patients with estimated glomerular filtration rates <30 mL/min/1.73 m² have frequently been excluded from large, randomized clinical trials. Although this situation is slowly changing, in everyday practice we continue to struggle with problems that are not clearly addressed in the guidelines. This literature review was conducted by an interdisciplinary group, which comprised a nephrologist, internal medicine specialists, and cardiologist. In this review, we discuss the difficulties in ruling out HF for patients with advanced CKD and issues regarding the cardiotoxicity of dialysis fistulas and the occurrence of pulmonary hypertension in patients with CKD. Due to the recent publication of the new HF guidelines by the European Society of Cardiology, this is a good time to address these difficult issues. Contrary to appearances, these are not niche issues, but problems that affect many patients.

Chest Ultrasound as a New Tool for Assessment of Volume Status in Hemodialysis Patients

Accurate assessment of volume status (VS) in hemodialysis (HD) patients is challenging. The use of chest ultrasound (CUS) for detection of extravascular lung water has recently gained wide acceptance. The aim of this study was to evaluate the use of CUS in VS assessment in HD patients in comparison to clinical and inferior vena cava (IVC) indices and to assess their relation with volume displacement after ultrafiltration. This prospective cohort study was carried out on 38 patients on regular HD. VS was assessed using a 13-point clinical score, and IVC indices and CUS score were measured pre- and post-ultrafiltration. Correlation between these parameters and with ultrafiltration volume was tested. There was a statistically significant reduction in post-ultrafiltration CUS score and the 13-point clinical score (P < 0.01). Moreover, reduction in all the IVC indices (inspiratory and expiratory diameters and collapsing index) was detected, but did not reach statistical significance (P = 0.185, P = 0.296, and P = 0.194, respectively). CUS score had statistically significant correlations with ultrafiltration volume and New York Heart Association classes (P < 0.001 and <0.001, respectively). Neither clinical signs nor IVC indices can be used independently for the assessment of VS in HD patients. CUS is a useful guide in VS assessment, and we recommend its routine use in the management of HD patients. Concomitant use of bio- impedance analysis (BIA) may be needed in addition to CUS for more accurate assessment of VS in HD patients.

Assessment and Management of Volume Overload Among Patients on Chronic Dialysis

Volume overload is the most common complication in end-stage renal disease (ESRD) patients, being directly related to numerous complications including resistant hypertension, cardiac hypertrophy, congestive heart failure or arterial stiffness, among others. Therefore, volume overload is now considered an important risk factor for hard outcomes, like all-cause or cardiovascular mortality. Relying solely on clinical examination for assessing volume overload in ESRD patients lacks sensitivity and specificity. Numerous efforts have been made to identify new methods that could objectively assess volume status; however, each of them has important limitations. This review aims to discuss the most frequently used methods (biomarkers, inferior vena cava assessment, lung ultrasonography, bioimpedance analysis and blood volume monitoring) and to compare the advantage of each method vs. the overall/ clinical strategy.

The Conundrum of Volume Status Assessment: Revisiting Current and Future Tools Available for Physicians at the Bedside

Assessment of patients’ volume status at the bedside is a very important clinical skill that physicians need in many clinical scenarios. Hypovolemia with hypotension and tissue under-perfusion are usually more alarming to physicians, but hypervolemia is also associated with poor outcomes, making euvolemia a crucial goal in clinical practice. Nevertheless, the assessment of volume status can be challenging, especially in the absence of a gold standard test that is reliable and easily accessible to assist with clinical decision-making. Physicians need to have a broad knowledge of the individual non-invasive clinical tools available for them at the bedside to evaluate volume status. In this review, we will discuss the strengths and limitations of the traditional tools, which include careful history taking, physical examination, and basic laboratory tests, and also include the relatively new tool of point-of-care ultrasound.

Vascular endothelial growth factor D is a biomarker of fluid overload in haemodialysis patients

BACKGROUND

Improved understanding and assessment of the complex physiology of volume regulation in haemodialysis (HD) patients are required to improve patient care and reduce mortality associated with fluid overload (FO).

METHODS

We searched for FO-related biomarkers among 184 peptides associated with cardiovascular disease in a cohort of 30 HD patients. First, we assessed the direct impact of HD on the peptides of interest by comparing plasma concentrations before and after treatment. Then, we compared cardiovascular peptide profiles between patients with and without FO as defined by bioimpedance analysis (BIA). The plasma concentration of selected candidate biomarkers for FO was determined by enzyme-linked immunosorbent assay (ELISA) and correlated with previously described FO-related clinical and laboratory parameters. For validation, results were confirmed in an independent cohort of 144 HD patients.

RESULTS

We found seven peptides positively [NT-proBNP, B-type natriuretic peptide (BNP), vascular endothelial growth factor D (VEGFD), tumour necrosis factor-related apoptosis-inducing ligand receptor 2, growth differentiation factor 15, tumour necrosis factor ligand superfamily member 13B, chitinase-3-like protein 1] and five negatively (leptin, renin, epidermal growth factor receptor, interleukin-1 receptor antagonist, myeloblastin) correlated to FO. In addition to natriuretic peptides, VEGFD emerged as third peptide highly correlated with BIA (ρ = 0.619, P < 0.0001). In line with this, VEGFD concentration verified by ELISA correlated with BIA, BNP and soluble CD146 but not with vascular endothelial growth factor C (VEGFC). Notably, levels of VEGFD were unrelated to cardiac systolic function (P = 0.63), contrary to BNP (P = 0.0003). Finally, we observed that 1-year all-cause mortality was higher in patients with high BNP (P = 0.0002), FO (defined by BIA, P = 0.04) and high VEGFD (P = 0.02), but not with high VEGFC (P = 0.48).

CONCLUSION

VEGFD is a novel FO-related biomarker with unique diagnostic and prognostic properties.

Lung Ultrasound: A "Biomarker" for Fluid Overload?

Fluid overload is associated with poor outcomes in patients with acute kidney injury as well as end-stage kidney disease. Lung ultrasound (LUS) has been used in many different settings and specialties including the emergency department, intensive care unit, trauma, cardiology, and nephrology. Although LUS has been a valuable tool in assessing pulmonary congestion, LUS findings may not always be pathognomonic for pulmonary congestion. Furthermore, the feasibility of doing an extensive LUS examination as has been done in research studies may be hard to implement within the clinical setting. This review will go over the use of LUS to evaluate for fluid overload, compare LUS with other markers of fluid overload, review limitations of LUS, and suggest potential future directions in the use of LUS in nephrology.

Physical examination for the detection of hypervolemia among patients on chronic dialysis: A diagnostic-test study

INTRODUCTION

Assessment of dry-weight among patients on dialysis is challenging in the absence of reliable markers to define fluid overload (FO). This study aimed to explore the value of two simple clinical signs, pedal edema, and crackles at pulmonary auscultation, in diagnosing hypervolemia, using bioimpendence spectroscopy (BIS) as reference standard.

METHODS

In a cohort of 107 asymptomatic dialysis patients, FO was assessed with physical examination and BIS shortly before the mid-week dialysis session. Patients were also asked to perform home blood pressure (BP) monitoring with a validated, automatic device (HEM-705, Omron, Healthcare) for 1 week in order to determine their BP outside of dialysis.

FINDINGS

Patients within the high tertile of predialysis FO had longer dialysis vintage, lower serum albumin and higher home systolic BP, despite the more aggressive treatment with a higher average number of antihypertensives daily. In receiver-operating-characteristic (ROC) curve analysis, pedal edema (area under curve [AUC]: 0.534; 95% confidence interval [CI]: 0.416-0.651) and pulmonary crackles (AUC: 0.551; 95% CI: 0.432-0.671) had limited accuracy in detecting excess predialysis FO > 2.2 L. The agreement of pedal edema (k-coefficient: 0.065) and pulmonary crackles (k-coefficient: 0.122) with BIS-derived FO was poor. In multivariate linear regression analysis, longer dialysis vintage (β: 0.306, p < 0.001) and higher home systolic BP (β: 0.287, p < 0.01) were the two factors that were associated with predialysis FO.

CONCLUSIONS

This study showed that among asymptomatic dialysis patients, pedal edema and pulmonary crackles in physical examination had limited discriminatory power in detection of FO, as assessed with the method of BIS.

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.

Intradialytic systolic blood pressure variation can predict long-term mortality in patients on maintenance hemodialysis

PURPOSE

It is unclear which time-points of intradialytic blood pressure (BP) best predict prognosis. Thus, it is important to assess the association between different time-points of intradialytic BP and prognosis in clinical practice.

METHODS

We recruited patients who underwent hemodialysis from January 2014 to June 2014. Data about dialysis were collected, including intradialytic BP. Cox regression analysis was performed to examine the association between different time-points of intradialytic BP and clinical events, with a follow-up through December 31, 2019. The primary endpoint was all-cause mortality.

RESULTS

A total of 216 patients were recruited and 62 (30.7%) patients died (6.1 per 100-person year) during the follow-up. Intradialytic SBP varied greatly in fatalities. Univariate and multivariate Cox regression models indicated that the adjusted hazard ratio for death was 1.80 and 5.06 when intradialytic systolic blood pressure (SBP) variation was analyzed in increments of 20 mmHg. Furthermore, we divided intradialytic SBP variation into three categories: < 15 mmHg, 15 ~ 30 mmHg,  ≥ 30 mmHg. Kaplan-Meier analysis indicated that both all-cause mortality and cardiovascular mortality increased significantly for patients with intradialytic SBP variation over 30 mmHg (P = 0.006 and 0.021). Univariate and multivariate Cox regression models indicated that the adjusted hazard ratio for death was 3.78 and 12.62 as intradialytic SBP variation ≥ 30 mmHg vs. intradialytic SBP variation < 15 mmHg.

CONCLUSION

Intradialytic SBP variation, rather than BP of specific intradialytic time-points, has the potential to predict long-term mortality in hemodialysis patients. BP stability is crucial for patients' prognosis.

Volume Balance in Chronic Kidney Disease: Evaluation Methodologies and Innovation Opportunities

BACKGROUND

Patients affected by chronic kidney disease are at a risk of cardiovascular morbidity and mortality. Body fluids unbalance is one of the main characteristics of this condition, as fluid overload is highly prevalent in patients affected by the cardiorenal syndrome.

SUMMARY

We describe the state of the art and new insights into body volume evaluation. The mechanisms behind fluid balance are often complex, mainly because of the interplay of multiple regulatory systems. Consequently, its management may be challenging in clinical practice and even more so out-of-hospital. Availability of novel technologies offer new opportunities to improve the quality of care and patients' outcome. Development and validation of new technologies could provide new tools to reduce costs for the healthcare system, promote personalized medicine, and boost home care. Due to the current COVID-19 pandemic, a proper monitoring of chronic patients suffering from fluid unbalances is extremely relevant. Key Message: We discuss the main mechanisms responsible for fluid overload in different clinical contexts, including hemodialysis, peritoneal dialysis, and heart failure, emphasizing the potential impact provided by the implementation of the new technologies.

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.

Approach to Electrolyte Abnormalities, Prerenal Azotemia, and Fluid Balance

Volume and electrolyte evaluation and management is seen frequently in primary care practices. Some of the most common abnormalities encountered in outpatient practices are prerenal azotemia, dysnatremias, and altered potassium levels. Perturbations in volume or electrolyte concentrations can lead to serious organ dysfunction as well as hemodynamic collapse. This review focuses on the maintenance and regulation of intravascular volume and electrolytes, specifically sodium and potassium.

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.

Tracking hydration status changes by bioimpedance spectroscopy in children on peritoneal dialysis

BACKGROUND

This 6-month prospective longitudinal study investigates the association between hydration status changes using bioimpedance spectroscopy (BIS) and systolic blood pressure (SBP), pulse pressure (PP), and serum albumin (sAlb) changes in children on peritoneal dialysis (PD).

METHODS

Thirteen patients (median age: 12.58 years) were enrolled. Normal hydration, moderate hydration, severe overhydration, and dehydration were defined as -7% ≤ relative overhydration (Re-OH) < +7%, +7% ≤ Re-OH < +15%, Re-OH ≥ +15%, and Re-OH < -7%, respectively. Automated office blood pressure z-score, sAlb, and weight z-score were recorded.

RESULTS

Fifty-two Re-OH measurements were recorded: three in five, four in five, five in two, and seven in one patient, respectively. SBP was higher and sAlb lower in cases with severe overhydration (9 readings) (p < 0.001, p < 0.001), but distribution of these parameters did not differ between normal hydration/dehydration (28 readings) and moderate overhydration (15 readings) cases. In patients with hydration status change, SBP and PP were higher while sAlb lower in cases with higher hydration status level (p = 0.026, p = 0.05, and p = 0.109, respectively). In all patients, visit-to-visit SBP, PP, and sAlb changes were correlated to Re-OH changes (rs = 0.693, p < 0.001; rs = 0.643, p < 0.001; rs = -0.444, p = 0.008, respectively) but not to weight changes (rs = 0.052, p = 0.754; rs = 0.034, p = 0.838; rs = -0.156, p = 0.378, respectively). Visit-to-visit Re-OH changes, which were >+4% or <-4%, were linearly correlated to SBP (r = 0.858, p < 0.001), PP (r = 0.757, p < 0.001), and sAlb (r = -0.699, p = 0.002) changes.

CONCLUSION

In children on PD, longitudinal Re-OH changes are superior to weight changes in assessing volume-dependent variations of SBP, PP, and sAlb. Routine BIS application, rather than single BIS measurements, seems useful in the intra-patient monitoring of hydration status.

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.

Towards personalized fluid monitoring in haemodialysis patients: thoracic bioimpedance signal shows strong correlation with fluid changes, a cohort study

Background

Haemodialysis (HD) patients are burdened by frequent fluid shifts which amplify their comorbidities. Bioimpedance (bioZ) is a promising technique to monitor changes in fluid status. The aim of this study is to investigate if the thoracic bioZ signal can track fluid changes during a HD session.

Methods

Prevalent patients from a single centre HD unit were monitored during one to six consecutive HD sessions using a wearable multi-frequency thoracic bioZ device. Ultrafiltration volume (UFV) was determined based on the interdialytic weight gain and target dry weight set by clinicians. The correlation between the bioZ signal and UFV was analysed on population level. Additionally regression models were built and validated per dialysis session.

Results

66 patients were included, resulting in a total of 133 HD sessions. Spearman correlation between the thoracic bioZ and UFV showed a significant strong correlation of 0.755 (p < 0.01) on population level. Regression analysis per session revealed a strong relation between the bioZ value and the UFV (R² = 0.982). The fluid extraction prediction error of the leave-one-out cross validation was very small (56.2 ml [− 121.1–194.1 ml]) across all sessions at all frequencies.

Conclusions

This study demonstrated that thoracic bioZ is strongly correlated with fluid shifts during HD over a large range of UFVs. Furthermore, leave-one-out cross validation is a step towards personalized fluid monitoring during HD and could contribute to the creation of autonomous dialysis.

The Nephrologist as an Ultrasonographer

Ultrasonography is increasingly being used in the practice of nephrology, whether it is for diagnosis or management of acute or chronic kidney dysfunction, until progression to end-stage kidney disease, including preoperative assessment, access placement, and diagnosis and management of dysfunctional hemodialysis access. Point-of-care ultrasounds are also being used by nephrologists to help manage volume status, especially in patients admitted to the intensive care units, and more recently, for guiding fluid removal in the outpatient dialysis units. Fundamental knowledge of sonography has become invaluable to the nephrologist, and performance and interpretation of ultrasound has now become an essential tool for practicing nephrologists to provide patient-centered care, maximize efficiency, and minimize fragmentation of care. This review will address the growing role of ultrasonography in the management of a patient with CKD from the point of initial contact with the nephrologist throughout the spectrum of kidney disease and its consequences.

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

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

Uncertainties in BP management in dialysis patients

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

Diagnosis and Management of Pulmonary Hypertension in Patients With CKD

Pulmonary hypertension (PH) is a highly prevalent and important condition in adults with chronic kidney disease (CKD). In this review, we summarize the definition of PH, discuss its pathophysiology and classifications, and describe diagnostic and management strategies in patients with CKD, including those with kidney failure treated by kidney replacement therapy. In the general population, PH is classified into 5 groups based on clinical presentation, pathology, hemodynamics, and management strategies. In this classification system, PH in CKD is placed in a diverse group with unclear or multifactorial mechanisms, although underlying cardiovascular disease may account for most cases. CKD may itself directly incite pulmonary circulatory dysfunction and remodeling through uremic toxins, inflammation, endothelial dysfunction, and altered vasoregulation. Despite several studies describing the higher prevalence of PH in CKD and kidney failure, along with an association with poor outcomes, high-quality evidence is not available for its diagnostic and management strategies in those with CKD. In CKD not requiring kidney replacement therapy, volume management along with treatment of underlying risk factors for PH are critical. In those receiving hemodialysis, options are limited and transition to peritoneal dialysis may be considered if recurrent hypotension precludes optimal volume control.

Bioimpedance spectroscopy for fluid status assessment in patients with decompensated liver cirrhosis: Implications for peritoneal dialysis

Bioimpedance spectroscopy (BIS) is routinely used in peritoneal dialysis patients and might aid fluid status assessment in patients with liver cirrhosis, but the effect of ascites volume removal on BIS-readings is unknown. Here we determined changes in BIS-derived parameters and clinical signs of fluid overload from before to after abdominal paracentesis. Per our pre-specified sample size calculation, we studied 31 cirrhotic patients, analyzing demographics, labs and clinical parameters along with BIS results. Mean volume of the abdominal paracentesis was 7.8 ± 2.6 L. From pre-to post-paracentesis, extracellular volume (ECV) decreased (20.2 ± 5.2 L to 19.0 ± 4.8 L), total body volume decreased (39.8 ± 9.8 L to 37.8 ± 8.5 L) and adipose tissue mass decreased (38.4 ± 16.0 kg to 29.9 ± 12.9 kg; all p < 0.002). Correlation of BIS-derived parameters from pre to post-paracentesis ranged from R² = 0.26 for body cell mass to R² = 0.99 for ECV. Edema did not correlate with BIS-derived fluid overload (FO ≥ 15% ECV), which occurred in 16 patients (51.6%). In conclusion, BIS-derived information on fluid status did not coincide with clinical judgement. The changes in adipose tissue mass support the BIS-model assumption that fluid in the peritoneal cavity is not detectable, suggesting that ascites (or peritoneal dialysis fluid) mass should be subtracted from adipose tissue if BIS is used in patients with a full peritoneal cavity.

Dialysis-specific factors and incident atrial fibrillation in hemodialysis patients

Background

Atrial fibrillation (AF) is common in end-stage renal disease patients. Besides the traditional risk factors, we aimed to find dialysis-specific factors for developing incident AF.

Methods

From March 2017 to August 2018, we retrospectively reviewed all outpatient-based prevalent hemodialysis patients in our artificial kidney room, and they were followed up until August 2019. Dialysate calcium concentration (3 versus 2.5 mEq/L), time length (4 versus 3.5 h), frequency (thrice weekly versus twice weekly), dialyzer size (effective surface area of 1.4 m² versus 1.8 m²), membrane permeability (high flux versus low flux), ultrafiltration rate (mL/kg/hour), and blood flow rate (mL/min) were evaluated.

Results

Among a total of 84 patients, 15 (17.9%) had newly detected AF with a follow-up period of 21 (13.3–24) months. By performing multivariate Cox regression analysis, blood flow rate (mL/min) and ultrafiltration rate (mL/kg/h) were considered significant factors for developing incident AF (adjusted hazard ratio [HR], 0.977; p = 0.011 and adjusted HR, 1.176; p = 0.013, respectively), while dialysis bath, time length, and frequency, dialyzer size, and membrane type were not considered significant factors. Ultrafiltration cutoff rate of 8.6 mL/kg/h was the best predictive factor for incident AF (area under the curve-receiver operating characteristic [AUC-ROC], 0.746; p < 0.005), while blood flow rate was not considered a significant factor for incident AF in ROC analysis (AUC-ROC, 0.623; p = 0.126). Ultrafiltration rate was largely dependent on interdialytic weight gain (p < 0.005, linear-by-linear association).

Conclusion

Higher ultrafiltration rate was associated with incident AF in hemodialysis patients.

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.

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.

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.

Systolic and diastolic hypertension among patients on hemodialysis: Musings on volume overload, arterial stiffness, and erythropoietin

Hypertension among patients on hemodialysis is predominantly systolic (either isolated or combined with diastolic hypertension), whereas the scenario of isolated diastolic hypertension is rare and more common in younger patients. Uncontrolled hypertension that persists despite aggressive antihypertensive drug therapy is a reflection of the volume overload that is a prominent mediator of systolic and diastolic BP elevation. Clinical-trial evidence supports the notion that dry-weight probing is an effective strategy to improve BP control, even when overt clinical signs and symptoms of volume overload are not present. Accelerated arterial stiffness influences the patterns and rhythms of interdialytic ambulatory BP and is a major determinant of isolated systolic hypertension in hemodialysis. Posthoc analyses of the Hypertension in Hemodialysis patients treated with Atenolol or Lisinopril (HDPAL) trial, however, suggest that arterial stiffness does not make hypertension more resistant to therapy and is unable to predict the treatment-induced improvement in left ventricular hypertrophy. A combined strategy of sodium restriction, dry-weight adjustment, and antihypertensive medication use was effective in improving ambulatory BP control regardless of the severity of underlying arteriosclerosis in HDPAL. Other nonvolume-dependent mechanisms, such as erythropoietin use, appear to be also important contributors and should be taken into consideration, particularly in younger hemodialysis patients with diastolic hypertension. In this article, we explore the role of volume overload, arterial stiffness, and erythropoietin use as causes of systolic vs diastolic hypertension in patients on hemodialysis. We conclude with clinical practice recommendations and with a call for a "volume-first" approach when managing hemodialysis hypertension.

Is N-terminal pro-brain natriuretic peptide a reliable marker for body fluid status in children with chronic kidney disease?

INTRODUCTION

Brain natriuretic peptides, released in response to left ventricular stress, have a strong prognostic value in dialysis patients. However, their role in detecting abnormalities of fluid status is under debate; the relationship between volume status and brain natriuretic peptides (BNPs) differs among various studies. The aim of our study was to evaluate the clinical utility of N-terminal proBNP in the assessment of fluid status and cardiovascular risk in this setting.

MATERIAL AND METHODS

The study included 65 children: 10 pre-dialysis, 13 hemodialysis, 12 peritoneal dialysis patients and 30 healthy controls. Volume status was determined by multifrequency bioimpedance and NT-pro-BNP, as well as echocardiography to estimate the left ventricle structure and function.

RESULTS

The median log NT-proBNP values of hemodialysis and peritoneal dialysis patients were 3.66 (2.05-4.90) and 3.57 (2.51-4.13) pg/ml, respectively, and significantly higher compared with the control group (p < 0.001, p < 0.001). On simple correlation, NT-proBNP was correlated with markers of volume overload and cardiac dysfunction. On multivariate regression analysis, only left ventricle mass index (β = 0.402, p = 0.003) and left atrium diameter (β = 0.263, p = 0.018) were independently associated with NT-proBNP (adjusted R 2 of the model: 0.707, p < 0.001).

CONCLUSIONS

Our research suggested that NT-proBNP, which was correlated with LV systolic and diastolic dysfunction and fluid overload as assessed by bioimpedance, can be used to evaluate cardiovascular states in a chronic kidney disease (CKD) population. From the early stages of CKD, periodic monitoring of NT-proBNP levels may be essential for early detection of patients with high risk of cardiovascular events, and for taking preventive intervention as soon as possible.

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.

Monitoring Volume Status Using Bioelectrical Impedance Analysis in Chronic Hemodialysis Patients

Fluid overload can be an independent risk factor of cardiovascular events and all-cause death in end-stage renal disease (ESRD) patients on chronic hemodialysis. We performed a retrospective study to investigate whether intermittent control of fluid status decreases the rate of these complications using bioelectrical impedance analysis (BIA). In ESRD patients on chronic hemodialysis, we identified the ratio of extracellular water to total body water (ECW/TBW) every 6 months using InBody S10 (Biospace, Seoul, Korea), which was measured within 30 minutes after dialysis initiation on the first dialysis day of the week. The uncontrolled group included 57 (40.1%) patients with all ECW/TBW measurements ≥0.40; in contrast, the controlled group included 85 (59.9%) with any measured ECW/TBW <0.40. Included patients were followed for 29 (12-42) months. The risk of cardiovascular events was higher in the uncontrolled group (hazard ratio [HR], 2.4; 95% confidence interval [CI], 1.2-5.1; p < 0.05) than it was in the controlled group; however, this difference disappeared after adjusting for age, sex, and Charlson comorbidity index (not significant). On the other hand, the patients in the uncontrolled group had a higher risk of all-cause death than did those in the controlled group, independent of age, sex, and Charlson comorbidity index (HR, 4.7; 95% CI, 1.4-16.1; p < 0.05). In conclusion, monitoring volume status using BIA may help to predict all-cause death in chronic hemodialysis patients. Further controlled studies are needed to confirm that strict volume control could reduce the rates of cardiovascular events and mortality in this population.

Assessment and Management of Hypertension among Patients on Peritoneal Dialysis

Approximately 7%-10% of patients with ESKD worldwide undergo peritoneal dialysis (PD) as kidney replacement therapy. The continuous nature of this dialytic modality and the absence of acute shifts in pressure and volume parameters is an important differentiation between PD and in-center hemodialysis. However, the burden of hypertension and prognostic association of BP with mortality follow comparable patterns in both modalities. Although management of hypertension uses similar therapeutic principles, long-term preservation of residual diuresis and longevity of peritoneal membrane function require particular attention in the prescription of the appropriate dialysis regimen among those on PD. Dietary sodium restriction, appropriate use of icodextrin, and limited exposure of peritoneal membrane to bioincompatible solutions, as well as adaptation of the PD regimen to the peritoneal transport characteristics, are first-line therapeutic strategies to achieve adequate volume control with a potential long-term benefit on technique survival. Antihypertensive drug therapy is a second-line therapeutic approach, used when BP remains unresponsive to the above volume management strategies. In this article, we review the available evidence on epidemiology, diagnosis, and treatment of hypertension among patients on PD and discuss similarities and differences between PD and in-center hemodialysis. We conclude with a call for randomized trials aiming to elucidate several areas of uncertainty in management of hypertension in the PD population.

Extracellular Fluid Excess Is Significantly Associated With Coronary Artery Calcification in Patients With Chronic Kidney Disease

BACKGROUND

Extracellular fluid (ECF) excess is an independent predictor of cardiovascular morbidity in patients undergoing dialysis. This study aimed to investigate the relationship between ECF status, which is affected by renal function, and coronary artery calcification (CAC), which is a marker of cardiovascular disease, in patients with chronic kidney disease (CKD).

METHODS AND RESULTS

A total of 1741 patients at all stages of pre-dialysis CKD from the prospective observational cohort of CMERC-HI (Cardiovascular and Metabolic Disease Etiology Research Center-High Risk) were analyzed for the association between ECF status and CAC. ECF status was defined as extracellular water-to-total body water ratio (ECW/TBW) measured using bioelectrical impedance analysis. ECF excess was defined as ECW/TBW ≥0.390 or ≥0.400 depending on its severity. To define CAC, Agatston coronary artery calcium scores were measured. A total coronary artery calcium score of ≥400 was defined as CAC. The CKD stages were defined according to estimated glomerular filtration rate calculated using the CKD Epidemiology Collaboration equation. ECW/TBW and the proportion of ECF excess increased with progressing CKD stages. Multivariable logistic regression analyses showed that ECW/TBW was independently associated with CAC (per 0.01 increase of ECW/TBW, odds ratio 1.168, 95% confidence interval, 1.079-1.264, P<0.001). The adjusted R2 for predicting higher coronary artery calcium scores and CAC significantly improved after ECW/TBW was added to conventional factors. This association was further confirmed by net reclassification and integrated discriminant improvements, sensitivity analysis, and subgroup analysis.

CONCLUSIONS

ECF status is independently associated with a high risk of CAC in patients with CKD.

STUDY REGISTRATION

URL: https://www.clinicaltrials.gov/. Unique identifier: NCT02003781.