Hypervolemia is associated with increased mortality among hemodialysis patients

Utility of Central Venous Oxygen Saturation Gradient in Predicting Mortality in Dialysis with Catheter Access

BACKGROUND Central venous oxygen saturation (ScvO2), a biomarker that is well-correlated with arterial oxygen saturation, can predict mortality. Few studies have focused on blood volume, ScvO2, and mortality in patients on maintenance dialysis. This retrospective study used hospital record data of 144 dialysis patients with central venous catheter access (CVC) and aimed to evaluate the ScvO2 gradient, blood volume, and patient mortality. We examined the associations among absolute blood volume (ABV), mean ScvO2, intradialytic slope of ScvO2, and mortality in patients on dialysis. MATERIAL AND METHODS Adult patients receiving dialysis via CVC from 2022 to 2024 were enrolled. ScvO2, ABV, and protocol-based ultrafiltration were monitored using Crit-Line IV (Fresenius Medical Care, Bad Homburg, Germany). Participants were assessed and followed until death or administrative censor. Multiple fractional polynomial (MFP) regression was used to determine best-fitting polynomial function between predictors and mortality. We also constructed proportional hazard model to compare trends of ScvO2 for mortality. RESULTS In a total of 144 eligible patients, the incidence of mortality was 14.5 per 1000 patient-months. The correlation between mean ScvO2 and mortality was weak (r=-0.05), whereas the association between ABV change and mean ScvO2 were a reverse U curve. The intradialytic slope of ScvO2 was independently associated with mortality (adjusted odds ratio [95% CI]=0.421 [0.226-0.783], P<0.05). Those with descending slope of ScvO2 had higher risk of mortality than those with an ascending slope (HR [95% CI]=3.98 [1.22-13.03], P<0.05). CONCLUSIONS A negative trend of intradialytic ScvO2 was associated with mortality.

Modern tools for optimizing fluid management in dialysis patients: a comprehensive review

Maintaining optimal fluid balance is crucial for patients with end-stage renal disease on dialysis, as both fluid overload and excess removal can lead to poor outcomes. Traditional approaches such as physical exam and chest X-ray have limitations when assessing volume status. This review carefully examines the tools that provide more precise options, including lung ultrasound, echocardiography, Venous Excess Ultrasound (VEXUS), bioimpedance analysis (BIA), and passive leg raise (PLR). We discuss the principles, supporting evidence, and practical uses of these techniques differentiating between static and dynamic methods to evaluate ultrafiltration tolerance. By integrating these modern techniques with clinical judgment, nephrologists can optimize fluid management in dialysis patients. While these tools show promise, further research is needed to establish standardized protocols and evaluate their impact on patient-centered outcomes.

Dialysis parameters associated with SARS-CoV-2 infection and prognosis in end-stage kidney disease

BACKGROUND

The Covid-19 pandemic has affected patients with end-stage kidney disease (ESKD). Whether dialysis parameters have a prognostic value in ESKD patients with Covid-19 remains unclear.

MATERIALS AND METHODS

We retrospectively evaluated clinical characteristics, blood pressure (BP) and dialysis parameters in ESKD patients undergoing maintenance outpatient hemodialysis, with (Covid-ESKD) and without (No-Covid-ESKD) Covid-19, at four Brazilian hemodialysis facilities. The Covid-ESKD (n = 107; 54% females; 60.8 ± 17.7 years) and No-Covid-ESKD (n = 107; 62% females; 58.4 ± 14.6 years) groups were matched by calendar time. The average BP and dialysis parameters were calculated during the pre-infection, acute infection, and post-infection periods. The main outcomes were Covid-19 hospitalization and all-cause mortality.

RESULTS

Covid-ESKD patients had greater intradialytic and postdialysis systolic BP and lower predialysis weight, postdialysis weight, ultrafiltration rate, and interdialytic weight gain during acute-illness compared to 1-week-before-illness, while these changes were not observed in No-Covid-ESKD patients. After 286 days of follow-up (range, 276-591), there were 18 Covid-19-related hospitalizations and 28 deaths among Covid-ESKD patients. Multivariable logistic regression analysis showed that increases in predialysis systolic BP from 1-week-before-illness to acute-illness (OR, 95%CI = 1.06, 1.02-1.10; p = .004) and Covid-19 vaccination (OR, 95%CI = 0.16, 0.04-0.69; p = .014) were associated with hospitalization in Covid-ESKD patients. Multivariable Cox-regression analysis showed that Covid-19-related hospitalization (HR, 95%CI = 5.17, 2.07-12.96; p < .001) and age (HR, 95%CI = 1.05, 1.01-1.08; p = .008) were independent predictors of all-cause mortality in Covid-ESKD patients.

CONCLUSION

Acute Covid-19 illness is associated with variations in dialysis parameters of volume status in patients with ESKD. Furthermore, increases in predialysis BP during acute Covid-19 illness are associated with an adverse prognosis in Covid-ESKD patients.

Agreement between the EWGSOP2 and SDOC consensuses for sarcopenia in patients receiving hemodialysis: Findings of a cross sectional analysis from the SARC-HD study

BACKGROUND

Differences in definitions and operational diagnoses for sarcopenia create difficulties in understanding the epidemiology of the disease. We examined the prevalences of sarcopenia using the revised European Working Group on Sarcopenia in Older People (EWGSOP2) and the Sarcopenia Definitions and Outcomes Consortium (SDOC) consensuses and analyzed their level of agreement in patients receiving hemodialysis.

METHODS

Data from the SARCopenia trajectories and associations with clinical outcomes in patients receiving hemodialysis (SARC-HD) multicenter study in Brazil were analyzed. Muscle strength was assessed using handgrip strength, muscle mass by calf circumference, and physical performance by the 4-m gait speed test. Sarcopenia was diagnosed according to both the EWGSOP2 (low muscle strength plus low muscle mass) and the SDOC (low muscle strength plus low physical performance). The Cohen kappa statistic was used to determine the level of agreement between the consensuses.

RESULTS

838 patients (57.8 ± 15.0 years; 61% men) from 19 dialysis units were included. We found similar prevalences of sarcopenia between the consensuses (EWGSOP2, n = 128, 15.3%; SDOC, n = 105, 12.5%) but with weak agreement (50 of 233 patients, 21.5%; κ = 0.34, 95% CI 0.25-0.43). Agreement was also weak within age categories (≥60 years, κ = 0.34; <60 years, κ = 0.15; both P < 0.001). Of the 51 patients diagnosed by the EWGSOP2 criterion as having severe sarcopenia, all but 1 (98.0%) met the SDOC criterion for sarcopenia (κ = 0.61, 95% CI 0.52-0.70). Low muscle strength was more frequently diagnosed using the SDOC than with the EWGSOP2 (52.3% vs 25.9%).

CONCLUSION

We found a weak agreement between the EWGSOP2 and SDOC consensuses for the diagnosis of sarcopenia in patients receiving hemodialysis. Although still weak, agreement was marginally better for older patients. These findings highlight the importance of a global and standardized conceptual diagnosis of sarcopenia.

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

Key Points

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

Background

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

Methods

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

Results

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

Conclusions

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

Association of Bioimpedance Parameters with Increases in Blood Pressure during Hemodialysis

BACKGROUND

Intradialytic hypertension, defined as an increase in BP from pre- to post-hemodialysis (HD), affects 5%-15% of patients receiving maintenance HD and is associated with cardiovascular and all-cause mortality. Hypervolemia is believed to be a major etiological factor, yet the association of more objective biomarkers of volume status with intradialytic hypertension is not well described.

METHODS

In a post hoc analysis of the Frequent Hemodialysis Network Daily Trial ( n =234), using data from baseline, 1-, 4-, and 12-month visits ( n =800), we used random-effects regression to assess the association of bioimpedance estimates of volume (vector length) with post-HD systolic BP (continuous) and any increase in systolic BP (categorical) from pre- to post-HD. We adjusted models for randomized group; age; sex; self-reported race; Quételet (body mass) index; vascular access; HD vintage; hypertension; history of heart failure; diabetes; residual kidney function (urea clearance); pre-HD systolic BP; ultrafiltration rate; serum-dialysate sodium gradient; and baseline values of hemoglobin, phosphate, and equilibrated Kt/V urea.

RESULTS

The mean age of participants was 50±14 years, 39% were female, and 43% were Black. In adjusted models, shorter vector length (per 50 Ω/m) was associated with higher post-HD systolic BP (2.9 mm Hg; 95% confidence interval [CI], 1.6 to 4.3) and higher odds of intradialytic hypertension (odds ratio 1.66; 95% CI, 1.07 to 2.55). Similar patterns of association were noted with a more stringent definition of intradialytic hypertension (>10 mm Hg increase from pre- to post-HD systolic BP), where shorter vector length (per 50 Ω/m) was associated with a higher odds of intradialytic hypertension (odds ratio 2.17; 95% CI, 0.88 to 5.36).

CONCLUSIONS

Shorter vector length, a bioimpedance-derived proxy of hypervolemia, was independently associated with higher post-HD systolic BP and risk of intradialytic hypertension.

Coronary sinus diameter to estimate congestion and predict survival

Background

Congestion predicts a poor prognosis, but its assessment is challenging in clinical practice and requires a multiparametric approach. We investigated if the coronary sinus (CS) diameter can predict mortality in a human model of rapid fluid unloading.

Methods

We measured by echocardiography the CS, and the inferior vena cava (IVC) for comparison, in 60 patients with end-stage chronic kidney disease (ESKD) immediately before and after hemodialysis (HD; age 76 [57-81] years, 40% female, left ventricular ejection fraction 57 [53-56]%). Patients were prospectively followed up for all-cause mortality.

Results

HD-induced decongestion decreased the maximum diameters of both CS and IVC (p ≤ 0.001 for all). The maximum diameter of the CS (CSmax) was as accurate as the IVC maximum diameter and collapsibility for the identification of congestion, defined as pre-hemodialysis status (AUROC CSmax = 0.902 vs IVC = 0.895, p = n.s.). A CSmax diameter after hemodialysis > 9 mm predicted all-cause mortality at 12 months (Log-rank Chi square = 11.49, p < 0.001).

Conclusions

A persistently dilated CS after hemodialysis is a marker of residual congestion and predicts death at one year in high-risk ESKD patients.

The Association Between Fluid Overload and Endothelial Dysfunction in Chronic Kidney Failure Patients Undergoing Hemodialysis Twice a Week

BACKGROUND

Fluid overload causes excessive systemic vasoconstriction and decreased perfusion of peripheral tissues, leading to abnormalities in cardiopulmonary physiological functions. Prolonged fluid overload caused by inadequate hemodialysis may cause heart dilatation, left ventricular hypertrophy, hypertension, and a decrease in coronary reserves, which later will develop into coronary ischemia, leading to increased morbidity and mortality of cardiovascular disease (CVD). Endothelial dysfunction plays a role in excessive vasoconstriction on fluid overload. Brain natriuretic peptide (BNP) and asymmetric dimethylarginine (ADMA) are used as parameters of fluid overload and endothelial dysfunction, respectively. This study is conducted to describe the relationship between fluid overload with endothelial dysfunction.

METHOD

This study is a cross-sectional study of kidney failure patients who underwent hemodialysis twice weekly for at least three months. BNP and ADMA were used as parameters for fluid overload and taken prior to hemodialysis.

RESULT

From 126 subjects, the proportion with fluid overload (BNP>356 pg/ml) was found to be 64.3% with the median age of subjects being 52 years (47-62). There was 47.6% population with endothelial dysfunction (ADMA>100 ng/ml). Presumptive causes of primary chronic kidney disease (CKD) were hypertension (38.9%), diabetes mellitus (DM) (28.6%), and glomerulonephritis (21.4%). There was no significant association between fluid overload and endothelial dysfunction (PR=1,042, p=0.832 CI 95%=0.714-1.521).

CONCLUSION

There was no relationship between fluid overload and endothelial dysfunction.

Utility of a modified Controlling Nutritional Status score in mortality risk assessment of patients on hemodialysis

PURPOSE

Malnutrition is common among hemodialysis patients. A nutritional index may be important for their prognosis prediction. We examined the use of a modified version of the Controlling Nutritional Status (CONUT) score as a predictor of mortality in hemodialysis patients and investigated whether statin use modified the association.

METHODS

We conducted a retrospective cohort study in 1130 adults (mean age 67.7 years, 35.0% women) on maintenance hemodialysis at four outpatient dialysis clinics in Japan. The exposure of interest was modified CONUT scores calculated by one-time data of serum albumin and total cholesterol at baseline, or mean data of these measures using multiple blood test results. The primary outcome was all-cause mortality. We examined the association between modified CONUT groups (low-risk, middle-risk, and high-risk) and mortality using multivariate Cox proportional hazard regression and logistic regression models in overall patients and by statin use.

RESULTS

During a median follow-up of 6.6 years, 525 (46.5%) patients died. Analysis using both one-time and mean data showed increased mortality risk in the high-risk modified CONUT score group as compared to the low-risk group (mean data: HR 2.52, 95% CI 1.96, 3.24); when stratified by statin use, the effect appeared stronger among users (mean data: HR 5.84, 95% CI 2.98, 11.44). Strong predictive ability was observed, particularly for mortality risk at 5 year follow-up using mean data (AUC = 0.842).

CONCLUSION

Our results suggest that the modified CONUT score may be useful in helping clinicians quickly identify hemodialysis patients with poorer prognosis who may benefit from close monitoring and interventions.

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

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

Portable sauna stimulated-diaphoresis for the treatment of fluid-overload in peritoneal dialysis patients: A pilot study

Background

Fluid overload (FO) is a common problem in patients with peritoneal dialysis (PD), it is associated with adverse outcomes and may persist despite adjustements in PD therapy.

Objective

To evaluate the feasibility and safety of stimulated diaphoresis to reduce FO with the use of a portable sauna bath.

Methods

Open-label pilot study in patients on continuous ambulatory peritoneal dialysis (CAPD) and FO. The primary outcome was the treatment-related adverse events; secondary outcomes were changes in over-hydration (OH), body weight and blood pressure, FO symptoms, and sleep quality. Dialysis prescription and daily data were recorded. The intervention period consisted in a 30-min, 45°C sauna bath, daily for 10 days, using a portable sauna bath.

Results

Fifty-one out of 54 total sauna bath sessions were well tolerated. In three (5.5%) sessions adverse effects were reported: transient dizziness in two cases, and a second-degree skin burn in a patient with advanced diabetic neuropathy. OH (6.3 ± 1.2 L vs. 5.5 ± 1.3 L, p = 0.05), body weight (67.7 ± 11.4 vs. 66.8 ± 3.8 kg, p = 0.003), diastolic blood pressure (92 ± 13.5 vs. 83 ± 13.3 mmHg, P = 0.003) and PSQI score (7.3 ± 3.7 vs. 5.1 ± 3.2, p = 0.02) improved significantly between the control and intervention period, respectively.

Conclusions

Stimulated diaphoresis with a portable sauna bath could be a novel, safe, and effective alternative way to reduce FO in CAPD patients. Larger studies are needed to confirm our results.

Clinical trial registration

ClinicalTrials.gov, identifier: NCT03563898.

OUP accepted manuscript

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

Inferior vena cava diameter and collapsibility index as a marker of fluid status in regular hemodialysis patients

Background

Patients with renal failure suffer from fluid overload which is a risk factor for mortality and morbidity. Therefore, fluid status assessment in patients on regular hemodialysis is very important. Dry weight assessment by clinical parameters is not always reliable. We evaluate the role of inferior vena cava ultrasound in estimating fluid overload in regular hemodialysis patients.

Results

A total of 45 persons, 30 end-stage renal disease patients on regular hemodialysis in group A (18 men and 12 women) and 15 healthy persons in group B (10 men and 5 women), were included in the study. The patients in group A ages ranged from 29 to 70 years with a mean of 48.38 ± 12.70 years and in group B ages ranged from 25 to 55 years with a mean of 34.93 ± 8.26. By clinical methods, the mean dry weight was 68.37 kg (68.37 ± 10.42). After HD mean, IVCe decreased from 2.01 ± 0.29 to 1.79 ± 0.22 cm (P < 0.001) similarly, mean IVCi decreased from 0.99 ± 0.48 to 0.64 ± 0.39 cm (P < 0.001). Changes in IVCD were significantly correlated with alterations in body weight following dialysis (P < 0.001). The IVC-CI increased significantly after dialysis (P < 0.001). IVCD and its IVC-CI reflected alterations in fluid status (P < 0.001). Considering the clinical parameters of fluid status, following HD mean, heart rate increased from 81.80 ± 5.15 beats per minute to 89.87 ± 6.42, (P < 0.001), systolic blood pressure decreased from 130 ± 18.43 mmHg to 113.33 ± 15.27 (P < 0.001), and diastolic blood pressure decreased from 80.17 ± 10.12 mmHg to 71.50 ± 9.29 (P < 0.001).

Conclusion

It was found a significant correlation between IVCD and IVC-CI with ultrafiltration of hemodialysis. Thus, IVC ultrasound can be used in dry weight assessment in ESRD patients on regular HD by measurement of IVCD and IVC-CI before and after hemodialysis.

Changes in total and segmental extracellular and intracellular volumes with hypotension during hemodialysis measured with bioimpedance spectroscopy

BACKGROUND

Bioelectrical impedance analysis (BIA) devices have been advocated to guide volume management in hemodialysis (HD) patients. We hypothesized that understanding the dynamics of fluid shifts in different body segments may provide additional insight on preventive measures to reduce the risk of intradialytic hypotension.

METHODS

A prospective observational study was conducted among 42 HD patients at risk of hypotension who were admitted as emergencies inpatient.

RESULTS

A total of 191 BIA measurements were made during the 42 HD sessions, and hypotension occurred during 52 measurements (27%). The extracellular water (ECW) to intracellular water ratio (EIR) was measured in different body segments and declined significantly only in the non-access arm with increasing HD session duration (β = -0.04; 95% confidence interval (CI): -0.05 to -0.03, p < 0.01). There was no significant association between EIR and hypotension with respect to the different body segments. Only pre-HD N-terminal-pro b-type natriuretic peptide was significantly associated with hypotension (β = 0.20, 95% CI: 0.04 to 0.89, p = 0.04). There was no association between relative blood volume monitoring change and EIR.

CONCLUSION

In summary, we found that segmental BIA during HD was unable to detect or predict hypotension during dialysis. Although BIA is able to provide information about ECW and guide clinical assessment of volume in HD patients prior to dialysis, our findings did not suggest the use of serial measurements of changes in EIR in different body segments during HD provided sufficient information to predict intradialytic hypotension. Similarly, changes in EIR did not provide information on changes in plasma volume that could potentially trigger interventions to prevent or reduce intra-dialytic hypotension.

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.

Dietary Advice in Hemodialysis Patients: Impact of a Telehealth Approach During the COVID-19 Pandemic

Objective

The purpose of this study was to assess the effect of a telehealth-delivered nutritional intervention via telephone in maintenance hemodialysis (HD) patients during the coronavirus outbreak.

Methods

This was a multicenter, observational, prospective, and longitudinal study of 156 patients undergoing maintenance HD from 15 dialysis units conducted during the COVID-19 pandemic. We assigned patients to receive dietary counseling through a phone call, according to their biochemical and nutritional parameters. Dry weight, intradialytic weight gain percentage (%IDWG), body mass index, potassium, phosphorus, calcium, calcium/phosphorus product, normalized protein catabolic rate, albumin, and hemoglobin were recorded at baseline and 1 month after nutrition counseling.

Results

The prevalence of hyperkalemia and hyperphosphatemia decreased significantly after dietary advice. A statistically significant reduction in serum potassium and phosphorus levels was observed in patients receiving counseling for hyperkalemia and hyperphosphatemia. In addition, there was a statistically significant decrease in the prevalence of hypophosphatemia. We also observed a significant decrease in %IDWG, although no statistically significant differences were detected in patients with high %IDWG. The data demonstrated statistically significant differences in potassium and phosphorus values when the person receiving the phone contact was the patient or the caregiver. The main statistically significant differences in hypophosphatemia %IDWG were only observed when contact was made directly with the patient. No differences were observed when the contact was made through nursing homes.

Conclusion

Our results suggest that telehealth-delivered dietary interventions can improve the clinical and nutritional parameters of HD patients. Consequently, this strategy may be effective for promoting continuous nutritional monitoring in these patients, in particular when conducting a face-to-face option is not crucial.

Cost-effectiveness and value of information analysis of multiple frequency bioimpedance devices for fluid management in people with chronic kidney disease having dialysis

Background

Among people with chronic kidney disease (CKD) on dialysis, sub-optimal fluid management has been linked with hospitalisation, cardiovascular complications and death. This study assessed the cost-effectiveness using multiple-frequency bioimpedance guided fluid management versus standard fluid management based on clinical judgment.

Methods

A Markov model was developed to compare expected costs, outcomes and quality adjusted life years of the alternative management strategies. The relative effectiveness of the bioimpedance guided approach was informed by a systematic review of clinical trials, and focussed reviews were conducted to identify baseline event rates, costs and health state utility values for application in the model. The model was analysed probabilistically and a value of information (VOI) analysis was conducted to inform the value of conducting further research to reduce current uncertainties in the evidence base.

Results

For the base-case analysis, the incremental cost-effectiveness ratio (ICER) for bioimpedance guided fluid management versus standard management was £16,536 per QALY gained. There was a 59% chance of the ICER being below £20,000 per QALY. Form the VOI analysis, the theoretical upper bound on the value of further research was £53 million. The value of further research was highest for parameters relating to the relative effectiveness of bioimpedance guided management on final health outcomes.

Conclusions

Multiple frequency bioimpedance testing may offer a cost-effective approach to improve fluid management in patients with CKD on dialysis, but further research would be of value to reduce the current uncertainties.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12962-021-00276-6.

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.

Clinical Relevance of Fluid Volume Status Assessment by Bioimpedance Spectroscopy in Children Receiving Maintenance Hemodialysis or Peritoneal Dialysis

Bioimpedance spectroscopy (BIS) is a noninvasive method used to evaluate body fluid volume status in dialysis patients, but reports on its effectiveness in pediatrics are scarce. We investigated the correlation between BIS and clinical characteristics and identified the changes in patients whose dialysis prescription was modified based on BIS. The medical records of children on maintenance dialysis who had undergone BIS between 2017 and 2019 were reviewed. Of the 49 patients, 14 were overhydrated, based on the >15% proportion of overhydration relative to extracellular water (OH/ECW) measured by BIS. Intake of ≥two antihypertensive medications was noted in the majority (85.7%) of children with fluid overload and only in 48.6% of those without fluid overload (p = 0.017). Elevated blood pressure despite medication use was significantly more common in patients with fluid overload than in those without fluid overload (78.6% vs. 45.7%, p = 0.037). Of the 14 overhydrated children, 13 (92.9%) had significant changes in body weight, OH/ECW, the number of antihypertensive drugs, left ventricular end-diastolic diameter, and cardiothoracic ratio after the change in dialysis prescription. BIS is a useful and noninvasive method to assess fluid status in dialysis children. Long-term follow-up and correlation with a more objective clinical indicator of fluid overload is necessary to verify the clinical effectiveness of BIS.

Metabolic syndrome in haemodialysis patients: prevalence, determinants and association to cardiovascular outcomes

BACKGROUND

In the general population, metabolic syndrome (MetS) is predictive of major adverse cardiovascular events (MACE). Waist circumference (WC), a component of the MetS criteria, is linked to visceral obesity, which in turn is associated with MACE. However, in haemodialysis (HD) patients, the association between MetS, WC and MACE is unclear.

METHODS

In a cross-sectional study of 1000 HD patients, we evaluated the prevalence and characterised the clinical predictors of MetS. The relationship between MetS and its components, alone or in combination, and MACE (coronary diseases, peripheral arteriopathy, stroke or cardiac failure), was studied using receiver operating characteristics (ROC) curves and logistic regression.

RESULTS

A total of 753 patients were included between October 2011 and April 2013. The prevalence of MetS was 68.5%. Waist circumference (> 88 cm in women, 102 cm in men) was the best predictor of MetS (sensitivity 80.2; specificity 82.3; AUC 0.80; p <  0.05). In multivariate analysis, MetS was associated with MACE (OR: 1.85; 95CI 1.24-2.75; p <  0.01), but not WC alone. There was a stronger association between the combination of abdominal obesity, hypertriglyceridaemia and low high-density lipoprotein cholesterol with MACE after exclusion of impaired fasting glucose and hypertension.

CONCLUSIONS

MetS is frequent and significantly associated with MACE in our haemodialysis cohort and probably in other European dialysis populations as well. In HD patients, a new simplified definition could be proposed in keeping with the concept of the "hypertriglyceridaemic waist".

Sodium Intake and Chronic Kidney Disease

In Chronic Kidney Disease (CKD) patients, elevated blood pressure (BP) is a frequent finding and is traditionally considered a direct consequence of their sodium sensitivity. Indeed, sodium and fluid retention, causing hypervolemia, leads to the development of hypertension in CKD. On the other hand, in non-dialysis CKD patients, salt restriction reduces BP levels and enhances anti-proteinuric effect of renin-angiotensin-aldosterone system inhibitors in non-dialysis CKD patients. However, studies on the long-term effect of low salt diet (LSD) on cardio-renal prognosis showed controversial findings. The negative results might be the consequence of measurement bias (spot urine and/or single measurement), reverse epidemiology, as well as poor adherence to diet. In end-stage kidney disease (ESKD), dialysis remains the only effective means to remove dietary sodium intake. The mismatch between intake and removal of sodium leads to fluid overload, hypertension and left ventricular hypertrophy, therefore worsening the prognosis of ESKD patients. This imposes the implementation of a LSD in these patients, irrespective of the lack of trials proving the efficacy of this measure in these patients. LSD is, therefore, a rational and basic tool to correct fluid overload and hypertension in all CKD stages. The implementation of LSD should be personalized, similarly to diuretic treatment, keeping into account the volume status and true burden of hypertension evaluated by ambulatory BP monitoring.

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.

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.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

DISCUSSION

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

Soluble CD146 and B-type natriuretic peptide dissect overhydration into functional components of prognostic relevance in haemodialysis patients

Background

Accurate volume status evaluation and differentiation of cardiac and non-cardiac components of overhydration (OH) are fundaments of optimal haemodialysis (HD) management.

Methods

This study, by combining bioimpedance measurements, cardiovascular biomarkers and echocardiography, aimed at dissecting OH into its major functional components, and prospectively tested the association between cardiac and non-cardiac components of OH with mortality. In the first part, we validated soluble CD146 (sCD146) as a non-cardiac biomarker of systemic congestion in a cohort of 30 HD patients. In the second part, we performed a prospective 1-year follow-up study in an independent cohort of 144 HD patients.

Results

sCD146 incrementally increased after the short and long intervals after HD (+53 ng/mL, P = 0.006 and  +91 ng/mL, P < 0.001), correlated with OH as determined by bioimpedance and well-diagnosed OH (area under the receiver operating characteristics curve 0.72, P = 0.005). The prevalence of OH was lower for low-sCD146 and low-BNP patients (B-type natriuretic peptide, 29%) compared with subjects with either one or both biomarkers elevated (65-74%, P < 0.001). Notably, most low-BNP but high-sCD146 subjects were overhydrated. Systolic dysfunction was 2- to 3-fold more prevalent among high-BNP compared with low-BNP patients (44-68% versus 21-23%, chi-square P < 0.001), regardless of sCD146. One-year all-cause mortality was markedly higher in patients with high-BNP (P = 0.001) but not with high-sCD146. In multivariate analysis, systolic dysfunction and BNP, but not OH, were associated with lower survival.

Conclusions

The combination of BNP and sCD146 dissects OH into functional components of prognostic value. OH in HD patients is associated with higher mortality only if resulting from cardiac dysfunction.

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.

Hypertension control among euvolemic hypertensive hemodialysis patients in Malaysia: a prospective follow-up study

OBJECTIVES

Existing literature does not provide enough information on evaluation of factors associated with pre-dialysis controlled hypertension among euvolemic hemodialysis (HD) patients. We conducted a study to evaluate the rate and factors influencing pre-dialysis controlled hypertension among euvolemic HD patients.

DESIGN

A multicenter prospective follow-up study.

SETTING

Tertiary care teaching hospital and its associated private dialysis centers.

PARTICIPANTS

This study included 145 euvolemic eligible hypertensive patients. Various sociodemographic, clinical factors and drugs were investigated and analyzed by using appropriate statistical methods to determine the factors influencing hypertension control among the study participants.

RESULTS

On baseline visit, the mean pre-dialysis systolic and diastolic BP (mmHg) of study participants was 161.2 ± 24. and 79.21 ± 11.8 retrospectively, and 30 (20.6%) patients were on pre-dialysis goal BP. At the end of the 6-months follow-up, the mean pre-dialysis systolic BP and diastolic BP (mmHg) of the patients was 154.6 ± 18.3 and 79.2 ± 11.8 respectively, and 42 (28.9%) were on pre-dialysis goal BP. In multivariate analysis, the use of calcium channel blockers (CCBs) was the only variable which had statistically significant association with pre-dialysis controlled hypertension at baseline (OR = 7.530, p-value = 0.001) and final (OR = 8.988, p-value < 0.001) visits.

CONCLUSIONS

In present study, the positive association observed between CCBs and controlled hypertension suggests that CCBs are effective antihypertensive drugs in the management of hypertension among euvolemic HD patients.

STRENGTHS AND LIMITATIONS OF THIS STUDY

This study involved a group of patients from tertiary-level teaching hospital and its associated private dialysis centers of Malaysia.To the best of the authors' knowledge, this is the first study to assess the factors influencing pre-dialysis controlled hypertension in a cohort of 145 euvolemic HD patients in a Malaysian setting.For determining the factors influencing hypertenion control multivariate analysis was conducted.Being a prospective follow-up study, the findings of the present study need to be interpreted with caution since it is limited to only 6 months follow up.Nevertheless, a multicenter study with a large sample size and longer follow up time is needed to confirm the findings of the current study.

Cardiorenal Interactions Revisited: How to Improve Heart Failure Outcomes in Patients With Chronic Kidney Disease

PURPOSE OF THE REVIEW

To summarize current advances in the understanding and management of heart failure (HF) in patients with advanced chronic kidney disease (CKD).

RECENT FINDINGS

Diagnosis of HF and treatment of congestion are crucial in the management of patients with advanced CKD to reduce symptoms, preserve organ function, and improve outcomes. Echocardiography and cardiovascular biomarkers may help to differentiate cardiac from non-cardiac components of overhydration. Renal replacement therapy or ultrafiltration may be required to treat congestion. Furthermore, patients with advanced CKD are frequently undertreated with disease-modifying HF therapies, but the use of beta-blockers and ACEi should be considered under close monitoring of kidney function and serum potassium. The use of the new oral potassium binders may translate into improved outcomes. The treatment of HF in patients with advanced CKD requires a multi-disciplinary approach. New diagnostic and therapeutic strategies are under evaluation and may contribute to improved outcomes.

Associations between Hemodialysis Facility Practices to Manage Fluid Volume and Intradialytic Hypotension and Patient Outcomes

BACKGROUND AND OBJECTIVES

Fluid overload and intradialytic hypotension are associated with cardiovascular events and mortality in patients on hemodialysis. We investigated associations between hemodialysis facility practices related to fluid volume and intradialytic hypotension and patient outcomes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data were analyzed from 10,250 patients in 273 facilities across 12 countries, from phase 4 of the Dialysis Outcomes and Practice Patterns Study (DOPPS; 2009-2012). Cox regression models (shared frailty) were used to estimate associations between facility practices reported by medical directors in response to the DOPPS Medical Directors Survey and all-cause and cardiovascular mortality and hospitalization, and cardiovascular events, adjusting for country, age, sex, dialysis vintage, predialysis systolic BP, cardiovascular comorbidities, diabetes, body mass index, smoking, residual kidney function, dialysis adequacy, and vascular access type.

RESULTS

Of ten facility practices tested (chosen a priori), having a protocol that specifies how often to assess dry weight in most patients was associated with lower all-cause (hazard ratio [HR], 0.78; 99% confidence interval [99% CI], 0.64 to 0.94) and cardiovascular mortality (HR, 0.72; 99% CI, 0.55 to 0.95). Routine orthostatic BP measurement to assess dry weight was associated with lower all-cause hospitalization (HR, 0.86; 99% CI, 0.77 to 0.97) and cardiovascular events (HR, 0.85; 99% CI, 0.73 to 0.98). Routine use of lower dialysate temperature to limit or prevent intradialytic hypotension was associated with lower cardiovascular mortality (HR, 0.76; 99% CI, 0.58 to 0.98). Routine use of an online volume indicator to assess dry weight was associated with higher all-cause hospitalization (HR, 1.19; 99% CI, 1.02 to 1.38). Routine use of sodium modeling/profiling to limit or prevent intradialytic hypotension was associated with higher all-cause mortality (HR, 1.36; 99% CI, 1.14 to 1.63), cardiovascular mortality (HR, 1.34; 99% CI, 1.04 to 1.73), and cardiovascular events (HR, 1.21; 99% CI, 1.03 to 1.43).

CONCLUSIONS

Hemodialysis facility practices relating to the management of fluid volume and intradialytic hypotension are associated with patient outcomes.

Role of Lung Ultrasound in Adjusting Ultrafiltration Volume in Hemodialysis Patients

Chronic fluid over-hydration is common in dialysis patients. It is associated with mortality and cardiovascular events. Optimal methods for adjusting fluid volume status and ideal dry weight remain uncertain. The purpose of this study was to evaluate the usefulness of ultrasound in quantifying body water. In 35 hemodialysis patients, we performed ultrasound of the chest, pre-tibial skin tissue thickness (TT), heart and inferior vena cava (IVC) before and after dialysis. We compared B-line scores of lungs, IVC diameters and cardiac functions in pre-dialysis and post-dialysis groups. We then estimated the correlations between ultrasound parameters and ultrafiltration volumes. Ultrafiltration parameters were adjusted prospectively for subsequent dialysis. As a result, both extravascular and intravascular water decreased during ultrafiltration. The median numbers of B-line scores (10 [0-42] vs. 4 [0-30]; p < 0.001); mitral valve blood flow velocities E (0.83 ± 0.23 m/s vs. 0.70 ± 0.20 m/s; p < 0.001), A (0.93 ± 0.28 vs. 0.89 ± 0.23 m/s; p < 0.001) and E/e' (12.47 ± 4.92 vs. 10.37 ± 4.0; p < 0.001); IVC diameters at end-expiration (17.51 ± 3.33 mm vs. 14.26 ± 3.45 mm; p < 0.001); and right pre-tibial TT (2.86 ± 1.36 mm vs. 2.43 ± 1.24 mm; p < 0.001) decreased during dialysis. Ultrafiltration volume was most associated with B-line score (adjusting for age and sex) (β = -3.340; p = 0.003). In addition, the B-line score after dialysis was significantly associated with left ventricular ejection fraction (r = -0.393; p = 0.019) and TT (r = -0.447; p = 0.007). Ultrafiltration volume was prospectively increased then if the B-line score was >6 in the previous dialysis. All patients tolerated the protocol well without any symptoms. Ultrafiltration volume was most associated with lung water, reflected by variation in B-line score. It was not associated with cardiac function, IVC diameter, IVC collapse rate or TT. Lung ultrasound is a useful imaging tool for dialysis patients.

Evaluation of factors affecting time to achieve dry weight among hemodialysis patients using bioimpedance spectroscopy

BACKGROUND

Achieving and maintaining dry weight appears to be an effective strategy for controlling and maintaining normotension among hypertensive patients on hemodialysis (HD).

OBJECTIVE

The present study aimed to determine the time at which the majority of patients achieve postdialysis dry weight using bioimpedance spectroscopy (BIS).

METHODS

A total of 220 HD patients were prospectively assessed for fluid overload using the Fresenius body composition monitor (BCM). BCM readings were taken at 30 and 45 min postdialysis.

RESULTS

Among the 220 patients included in this study, 120 (54.5%) achieved a euvolemic state at 30 min, and 25 (11.4%) achieved it at 45 min according to the BCM. In the multivariate analysis, vascular access other than arteriovenous fistula (AVF) (OR = 0.286, p value = 0.049) and cardiovascular disease (OR = 0.384, p value = 0.026) had a statistically significant negative association and receiving HD at Hospital Universiti Sains Malaysia (HUSM) (OR = 2.705, p value = 0.008) had a statistically significant positive association with achieving a euvolemic state at 30 min.

CONCLUSION

This suggests that assessing the hydration status at 45 min postdialysis in all patients or in those with identified risk factors for not achieving a euvolemic state at 30 min will provide a relatively accurate assessment for most patients.

Relationships of high cardiac output with ventricular morphology, myocardial energetics, and energy costs in hemodialysis patients with preserved ejection fraction

Hemodialysis patients have conditions that increase cardiac output (CO), including arteriovenous fistula, fluid retention, vasodilator use, and anemia. We sought to determine the relationships between these factors and CO and to evaluate the effects of the high-output states on ventricular morphology, function, and myocardial energetics in hemodialysis patients, using noninvasive load-insensitive indices. Cardiovascular function was assessed in hemodialysis patients with high output [ejection fraction ≥ 50%, cardiac index (CI) > 3.5 L/min/m², n = 30], those with normal output (CI < 3.0 L/min/m², n = 161), and control subjects without hemodialysis (n = 155). As compared to control subjects and hemodialysis patients with normal CI, patients with elevated CI were anemic and displayed decreased systemic vascular resistance index (SVRI), excessive left ventricular (LV) contractility, larger LV volume, and tachycardia. Lower hemoglobin levels were correlated with decreased SVRI, excessive LV contractility, and higher heart rate, while estimated plasma volume and interdialytic weight gain were associated with larger LV volume, thus increasing CO. High output patients displayed markedly increased pressure-volume area (PVA) and PVA/stroke volume ratio, which were correlated directly with CO. The use of combination vasodilator therapy (angiotensin-converting enzyme inhibitor/angiotensin-receptor blocker and calcium channel blocker) was not associated with high-output states. In conclusion, anemia and fluid retention are correlated with increased CO in hemodialysis patients. The high-output state is also associated with excessive myocardial work and energy cost.

Peridialysis BP levels and risk of all-cause mortality: a dose-response meta-analysis

Blood pressure (BP) management posed great challenge in hemodialysis (HD) population. We conducted a dose-response meta-analysis to investigate the quantitative features and the potential threshold effect of the associations between peridialysis BP levels and all-cause mortality risk in HD population. We searched all of the prospective cohort studies (published before 18 March 2017) on the associations between peridialysis BP levels and all-cause mortality risk. A total of 229,688 prevalent HD patients from 8 studies were included. Significant non-linear associations were noted between peridialytic BP levels and all-cause mortality risk. Significant increased risk of death was found in four peridialysis BP ranges, that is, low levels of predialysis SBP (<135 mmHg, 140 mmHg as the reference), two extremes of predialysis DBP (<55 and >95 mmHg, 90 mmHg as the reference), high levels of postdialysis SBP (>180 mmHg, 130 mmHg as the reference), and low levels of postdialysis DBP (<75 mmHg, 80 mmHg as the reference). Threshold effect was determined in the associations between peridialysis BP and all-cause mortality risk, and potential BP thresholds were identified (149 mmHg for predialysis SBP, 79 mmHg for predialysis DBP, 147 mmHg for postdialysis SBP and 76 mmHg for postdialysis DBP). In conclusion, the proposed peridialysis BP ranges and the threshold values could help clinicians identify high risk HD patients. The interpretation of the peridialysis BP mortality associations should be based on the features of HD population (especially the cardiovascular conditions, volume status and the dialysis vintage).

Plasma marinobufagenin immunoreactivity in patients with chronic kidney disease: a case control study

Experimental data have shown increased plasma levels of marinobufagenin in kidney failure. In this case-controlled retrospective analysis, we evaluated plasma marinobufagenin immunoreactivity in hemodialysis patients compared with subjects with normal kidney function. Sixty-eight adult hemodialysis patients with chronic kidney disease (34 females and 34 males) as well as 68 age-, gender-, and blood pressure-matched subjects without chronic kidney disease were enrolled. Patients on stable hemodialysis regimen for at least 3 mo before the study were included. Exclusion criteria were: age <18 yr, severe liver or heart insufficiency, and overhydration. Subjects without chronic kidney disease must have had an estimated glomerular filtration rate ≥60 ml·min^-1·1.72 m^-2 according to the Modification of Diet in Renal Disease formula. Plasma marinobufagenin immunoreactivity was significantly ( P < 0.001) higher in hemodialysis patients (1.66 ± 1.13 nmol/l) compared with subjects with normal kidney function (0.46 ± 0.23). In hemodialysis patients, plasma marinobufagenin immunoreactivity was higher in men compared with women. A significant positive correlation has been found between plasma marinobufagenin immunoreactivity and serum NT-proBNP, NT-proANP, or aldosterone concentrations in all analyzed subjects. In hemodialyzed patients with plasma marinobufagenin immunoreactivity above median value 5-yr, all-cause mortality was higher compared with those with plasma marinobufagenin concentration below median. We have shown that plasma marinobufagenin immunoreactivity is increased in patients with end-stage kidney failure treated with hemodialysis parallel to the increase in serum NT-proBNP, NT-proANP, and aldosterone concentrations. Higher marinobufagenin immunoreactivity has been associated with worse survival in hemodialyzed patients.

Arterial stiffness in end-stage renal disease-pathogenesis, clinical epidemiology, and therapeutic potentials

Arterial stiffness is an important risk factor for cardiovascular morbidity and mortality in patients with end-stage renal disease (ESRD). Arterial stiffness aggravates cardiovascular risk via multiple pathways, such as augmentation of aortic systolic pressure, subendocardial hypoperfusion, and excess pulsatile energy transmission from macro- to microcirculation. Pathogenesis of the arteriosclerotic process in ESRD is complex and not yet fully understood. Several factors unique to ESRD, such as mineral metabolism disturbances, vascular calcifications, formation of advanced glycation end-products, and acute and chronic volume overload, are proposed to play a particular role in the progression of arteriosclerosis in ESRD. As these and other mechanistic pathways of arterial stiffening in ESRD are elucidated, there is hope that this knowledge will be translated into novel therapeutic interventions targeting arterial stiffness. In the meantime, blood pressure (BP) lowering via strict volume control and appropriate use of antihypertensive drugs is a fundamental step in reversing accelerated arterial stiffening and modifying the cardiovascular risk profile of ESRD patients. In this article, we review the pathogenesis, clinical epidemiology, and therapies targeting arterial stiffness in ESRD, discussing recent advances and high-priority goals of future research in these important areas.

Novel Insights into the Pathogenesis and Prevention of Intradialytic Hypotension

BACKGROUND

Intradialytic hypotension (IDH) is a common complication of haemodialysis (HD) and associated with adverse outcomes, especially when a nadir definition (systolic blood pressure <90 mm Hg) is used. The pathogenesis of IDH is directly linked to the discontinuous nature of the HD treatment, in combination with patient-related factors such as age, diabetes mellitus and cardiac failure.

SUMMARY

Although the decline in blood volume due to removal of fluid by ultrafiltration is the prime mover, thermally induced reflex vasodilation compromises the haemodynamic response to hypovolemia. Recent studies have stressed the relevance of changes in tissue perfusion during HD, which may translate in long-term organ damage. Monitoring changes in tissue perfusion, for which emerging evidence becomes available, appears to have great promise in the fine-tuning of the dialysis procedure. Key Messages: While it is unlikely that IDH can be completely prevented, reduction in inter-dialytic weight gain, prevention of an increase in core temperature by adjusting the dialysate temperature and more frequent or prolonged dialysis treatment remain cornerstones in providing a more comfortable and safe treatment.

Multiple-frequency bioimpedance devices for fluid management in people with chronic kidney disease receiving dialysis: a systematic review and economic evaluation

BACKGROUND

Chronic kidney disease (CKD) is a long-term condition requiring treatment such as conservative management, kidney transplantation or dialysis. To optimise the volume of fluid removed during dialysis (to avoid underhydration or overhydration), people are assigned a 'target weight', which is commonly assessed using clinical methods, such as weight gain between dialysis sessions, pre- and post-dialysis blood pressure and patient-reported symptoms. However, these methods are not precise, and measurement devices based on bioimpedance technology are increasingly used in dialysis centres. Current evidence on the role of bioimpedance devices for fluid management in people with CKD receiving dialysis is limited.

OBJECTIVES

To evaluate the clinical effectiveness and cost-effectiveness of multiple-frequency bioimpedance devices versus standard clinical assessment for fluid management in people with CKD receiving dialysis.

DATA SOURCES

We searched major electronic databases [e.g. MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, Science Citation Index and Cochrane Central Register of Controlled Trials (CENTRAL)] conference abstracts and ongoing studies. There were no date restrictions. Searches were undertaken between June and October 2016.

REVIEW METHODS

Evidence was considered from randomised controlled trials (RCTs) comparing fluid management by multiple-frequency bioimpedance devices and standard clinical assessment in people receiving dialysis, and non-randomised studies evaluating the use of the devices for fluid management in people receiving dialysis. One reviewer extracted data and assessed the risk of bias of included studies. A second reviewer cross-checked the extracted data. Standard meta-analyses techniques were used to combine results from included studies. A Markov model was developed to assess the cost-effectiveness of the interventions.

RESULTS

Five RCTs (with 904 adult participants) and eight non-randomised studies (with 4915 adult participants) assessing the use of the Body Composition Monitor [(BCM) Fresenius Medical Care, Bad Homburg vor der Höhe, Germany] were included. Both absolute overhydration and relative overhydration were significantly lower in patients evaluated using BCM measurements than for those evaluated using standard clinical methods [weighted mean difference -0.44, 95% confidence interval (CI) -0.72 to -0.15, p = 0.003, I2 = 49%; and weighted mean difference -1.84, 95% CI -3.65 to -0.03; p = 0.05, I2 = 52%, respectively]. Pooled effects of bioimpedance monitoring on systolic blood pressure (SBP) (mean difference -2.46 mmHg, 95% CI -5.07 to 0.15 mmHg; p = 0.06, I2 = 0%), arterial stiffness (mean difference -1.18, 95% CI -3.14 to 0.78; p = 0.24, I2 = 92%) and mortality (hazard ratio = 0.689, 95% CI 0.23 to 2.08; p = 0.51) were not statistically significant. The economic evaluation showed that, when dialysis costs were included in the model, the probability of bioimpedance monitoring being cost-effective ranged from 13% to 26% at a willingness-to-pay threshold of £20,000 per quality-adjusted life-year gained. With dialysis costs excluded, the corresponding probabilities of cost-effectiveness ranged from 61% to 67%.

LIMITATIONS

Lack of evidence on clinically relevant outcomes, children receiving dialysis, and any multifrequency bioimpedance devices, other than the BCM.

CONCLUSIONS

BCM used in addition to clinical assessment may lower overhydration and potentially improve intermediate outcomes, such as SBP, but effects on mortality have not been demonstrated. If dialysis costs are not considered, the incremental cost-effectiveness ratio falls below £20,000, with modest effects on mortality and/or hospitalisation rates. The current findings are not generalisable to paediatric populations nor across other multifrequency bioimpedance devices.

FUTURE WORK

Services that routinely use the BCM should report clinically relevant intermediate and long-term outcomes before and after introduction of the device to extend the current evidence base.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016041785.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Validating the use of bioimpedance spectroscopy for assessment of fluid status in children

BACKGROUND

Bioimpedance spectroscopy (BIS) with a whole-body model to distinguish excess fluid from major body tissue hydration can provide objective assessment of fluid status. BIS is integrated into the Body Composition Monitor (BCM) and is validated in adults, but not children. This study aimed to (1) assess agreement between BCM-measured total body water (TBW) and a gold standard technique in healthy children, (2) compare TBW_BCM with TBW from Urea Kinetic Modelling (UKM) in haemodialysis children and (3) investigate systematic deviation from zero in measured excess fluid in healthy children across paediatric age range.

METHODS

TBW_BCM and excess fluid was determined from standard wrist-to-ankle BCM measurement. TBW_D2O was determined from deuterium concentration decline in serial urine samples over 5 days in healthy children. UKM was used to measure body water in children receiving haemodialysis. Agreement between methods was analysed using paired t test and Bland-Altman method comparison.

RESULTS

In 61 healthy children (6-14 years, 32 male), mean TBW_BCM and TBW_D2O were 21.1 ± 5.6 and 20.5 ± 5.8 L respectively. There was good agreement between TBW_BCM and TBW_D2O (R² = 0.97). In six haemodialysis children (4-13 years, 4 male), 45 concomitant measurements over 8 months showed good TBW_BCM and TBW_UKM agreement (mean difference - 0.4 L, 2SD = ± 3.0 L). In 634 healthy children (2-17 years, 300 male), BCM-measured overhydration was - 0.1 ± 0.7 L (10-90th percentile - 0.8 to + 0.6 L). There was no correlation between age and OH (p = 0.28).

CONCLUSIONS

These results suggest BCM can be used in children as young as 2 years to measure normally hydrated weight and assess fluid status.

Plasma Volume and Renal Function Predict Six-Month Survival after Hospitalization for Acute Decompensated Heart Failure

BACKGROUND

Plasma volume (PV) is contracted in stable patients with heart failure (HF) due to decongestion strategies. On the other hand, increased PV can adversely affect the trajectory of HF. We therefore examined the effects of increased percentage change in PV (%ΔPV), blood urea nitrogen (BUN), and %ΔPV stratified by BUN and glomerular filtration rate (GFR) on survival after discharge in patients hospitalized for acute decompensated HF (ADHF).

METHODS

We used the Strauss-Davis-Rosenbaum formula to calculate the %ΔPV between baseline and hospital discharge in a cohort from the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness trial (ESCAPE). Kaplan-Meier curves were constructed for survival over 6 months. Cox proportional hazards regression was used to obtain adjusted hazard ratios (HR) and 95% confidence intervals (95% CI) for the associations between survival after discharge and %ΔPV, BUN, and %ΔPV stratified by BUN and GFR.

RESULTS

Of the 324 patients included in our study (age 56.1 ± 13.6 years, 26.5% female), those with increased or no %ΔPV at discharge were less likely to survive at 6 months compared with those having reduced %ΔPV (log rank, p = 0.0093). Increased %ΔPV (HR 1.08 per 10% increase; 95% CI: 1.02-1.14) and increased BUN at discharge (HR 1.02 per mg/dL; 95% CI: 1.01-1.03) were independently associated with worse survival. Decreasing %ΔPV had a greater association with improved survival in patients with discharge BUN <31 mg/dL (p = 0.02) and discharge GFR >40 mL/min/1.73 m2 (p = 0.047).

CONCLUSIONS

Increased %ΔPV and BUN at discharge predicted worse 6-month survival in patients with ADHF. Decreased %ΔPV with low BUN or high GFR at discharge was associated with improved survival.

Value of bioimpedance analysis estimated "dry weight" in maintenance dialysis patients: a systematic review and meta-analysis

BACKGROUND

Volume overload is a common complication in patients with end-stage kidney disease who undergo maintenance dialysis therapy and associated with hypertension, left ventricular hypertrophy and mortality in this population. Although bioimpedance analysis (BIA), an objective method to assess overhydration, is associated with poor outcomes in observational studies, in randomized controlled trials (RCTs) the results were conflicting. We have examined the role of BIA for assessing the "dry weight" and fluid status in order to improve fluid overload in comparison with a control or clinical-based prescription in patients with ESKD receiving haemodialysis or peritoneal dialysis.

METHODS

All RCTs and quasi-RCTs in which BIA was used to improve fluid overload and assess the effect on all-cause mortality, cardiovascular morbidity, systolic blood pressure and volume control and arterial stiffness were included.

RESULTS

Seven RCTs with 1312 patients could be included in this review. In low-to-medium quality of the evidence, the use of BIA did not reduce all-cause mortality (relative risk 0.87, 95% CI 0.54-1.39) and had small to no effect on body change, but it improved systolic blood pressure control (mean difference (MD) -2.73 mmHg, 95% CI -5.00 to -0.46 mmHg) and reduce overhydration, as measured by BIA, with 0.43 L [(MD), 95% CI 0.71-0.15 L].

CONCLUSION

In ESKD patients, BIA-based interventions for correction of overhydration have little to no effect on all-cause mortality, whereas BIA improved systolic blood pressure control. Our results should be interpreted with caution as the size and power of the included studies are low. Further studies, larger or with a longer follow-up period, should be performed to better describe the effect of BIA-based strategies on survival.

Blood volume-monitored regulation of ultrafiltration to decrease the dry weight in fluid-overloaded hemodialysis patients: a randomized controlled trial

Background

Because chronic fluid volume overload is associated with higher mortality, we tested whether blood-volume monitored regulation of ultrafiltration and dialysate conductivity (UCR) and/or regulation of ultrafiltration and temperature (UTR) would facilitate dry weight reduction, in comparison to conventional dialysis (CONV).

Methods

We carried out a multicenter, 4-week, randomized controlled trial in hemodialysis patients ≥15% above normal extracellular fluid volume (ECV), per bioimpedance spectroscopy, who were randomized 1:1:1. Applying UCR (Nikkiso), UTR (Fresenius) and CONV, initial dry weight was reduced rapidly to target. Dry weight reduction was attenuated and eventually stopped at the occurrence of dialysis complications. The primary outcome was defined as intra- and postdialytic complications. Secondary outcomes were magnitudes of dry weight and blood pressure reduction.

Results

Of 244 patients assessed, N = 95 had volume overload ≥15% above normal ECV. Fifty patients received the allocated interventions (N = 16 UCR, N = 18 UTR, N = 16 CONV) and completed the trial. The rate of complications was significantly lower in UTR compared to CONV (21 ± 21% vs 34 ± 20%, p = 0.022), and also compared to UCR (vs 39 ± 27%, p = 0.028), but not statistically different between UCR and CONV (p = 0.93). Dry weight reduction was significantly higher in UTR compared to UCR (5.0 ± 3.4% vs 2.0 ± 2.7% body weight, p = 0.013), but not compared to CONV (vs 3.9 ± 2.1% body weight, p = 0.31). Systolic blood pressure reduction throughout the intervention phase was 17 ± 22 mmHg overall, but not significantly different between the three groups. Average maximum ultrafiltration rates were significantly higher in UTR than in UCR and CONV, at statistically similar dialysis times. Retrospective examination of randomly selected hemodialysis sessions in the UCR group identified technical mistakes in 36% of the dialysis sessions, despite considerable training efforts.

Conclusions

Even in patients with volume overload, fluid removal was challenging. Despite the relative advantage of UTR, which must be interpreted with caution in view of the poor technical execution of UCR, this study renders clear that fluid removal must not be reinforced rapidly. Apprehension of this obstacle is imperative for future clinical and academic endeavors aimed at improving dialysis outcomes by correcting volume status.

Trial registration

ClinicalTrials.gov (NCT01416753), trial registration date: August 12, 2011.

Setting the dry weight and its cardiovascular implications

Volume overload is common and associated with adverse outcomes in the hemodialysis population including systemic hypertension, pulmonary hypertension, left ventricular hypertrophy, and mortality. Since the beginning of the era of maintenance dialysis, prescribing and maintaining a dry weight remains the standard of care for managing volume overload on hemodialysis. Reducing dry weight even by relatively small amounts has been shown to improve blood pressure and has been associated with reductions in left ventricular hypertrophy. Maintaining an adequately low dry weight requires attention to sodium intake and adequate time on dialysis, as well as a high index of suspicion for volume overload. Reducing dry weight can provoke decreased cardiac chamber filling and is associated with risks including intradialytic hypotension. The ideal method to minimize intradialytic morbidity is unknown, but more frequent dialysis should be considered. Experimental methods of assessing volume status may allow identification of patients most likely both to tolerate and to benefit from dry weight reduction, but further study is needed.

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

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