Plasma brain natriuretic peptide concentration on assessment of hydration status in hemodialysis patient

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.

Higher NT-proBNP levels and the risk of intradialytic hypotension at hemodialysis initiation

INTRODUCTION

Elevated N-terminal pro B-type natriuretic peptide (NT-proBNP) is a potent predictor of adverse outcomes in hemodialysis initiation. These patients often experience intradialytic hypotension, which may partially reflect cardiac dysfunction, but the association of NT-proBNP with intradialytic hypotension is not clear.

METHODS

We performed a post hoc analysis of a randomized trial that tested mannitol versus placebo in 52 patients initiating hemodialysis (NCT01520207). NT-proBNP was measured prior to the first and third sessions (n = 87). Mixed-effects models (adjusting for randomized treatment, sex, race, age, diabetes, heart failure, catheter use, pre-dialysis systolic blood pressure, pre-dialysis weight, ultrafiltration volume, serum sodium, bicarbonate, urea nitrogen, phosphate, albumin, hemoglobin, and session length) were fit to examine the association of NT-proBNP with systolic blood pressure decline (pre-dialysis minus nadir systolic blood pressure). Additionally, mixed-effects Poisson models were fit to examine the association with intradialytic hypotension (≥20 mmHg decline in systolic blood pressure).

FINDINGS

Mean age was 55 ± 16 years; 33% had baseline heart failure. The median NT-proBNP was 5498 [25th-75th percentile 2011, 14,790] pg/mL; 26 sessions (30%) were complicated by intradialytic hypotension. In adjusted models, each unit higher log-NT-proBNP was associated with 6.0 mmHg less decline in systolic blood pressure (95%CI -9.2 to -2.8). Higher pre-dialysis NT-proBNP, per log-unit, was associated with a 52% lower risk of intradialytic hypotension (IRR 0.48, 95%CI 0.23-0.97), without evidence for effect modification by randomized treatment (P-interaction = 0.17).

DISCUSSION

In patients initiating hemodialysis, higher NT-proBNP is associated with less decline in intradialytic systolic blood pressure and lower risk of intradialytic hypotension. Future studies should investigate if higher pre-dialysis NT-proBNP levels may identify patients who might tolerate more aggressive ultrafiltration.

The significance of volume overload in the development of pulmonary arterial hypertension in continuous ambulatory peritoneal dialysis patients

INTRODUCTION

The underlying pathophysiology of pulmonary arterial hypertension (PAH) is multifactorial; however, the significance of chronic volume overload and its subsequent effects on cardiac function must be studied thoroughly. The main objective of this study was to determine the predictive parameters of PAH in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) using transthoracic echocardiography (TTE) and bioimpedance analysis (BIA).

METHODS

In this cross-sectional study, 43 eligible CAPD patients were chosen. The patients were examined by TTE and BIA before the morning dialysis session, and baseline patient characteristics, echocardiography, and BIA parameters were recorded.

RESULTS

Sixteen (37.2%) patients were diagnosed with PAH. Patients with PAH had significantly greater left atrial diameter (LAD), left ventricular mass index (LVMI), and higher grades of diastolic dysfunction (DDF). Systolic pulmonary artery pressure (sPAP) correlated with LAD (p < 0.001, r = 0.566), interventricular septal diameter (IVSD) (p = 0.004, r = 0.425), LVMI (p = 0.030, r = 0.323), and extracellular water/total body water (ECW/TBW) ratio (p = 0.002, r = 0.458).

CONCLUSION

Two volume status-related parameters including ECW/TBW ratio and inferior vena cava (IVC) expiratory diameter, and cardiac-related TTE findings such as LAD and DDF were predictors of sPAP in CAPD patients.

Plasma Brain Natriuretic Peptide Levels in Children with Chronic Kidney Disease and Renal Transplant Recipients: A Single Center Study

Pediatric chronic kidney disease (CKD) patients, as well as kidney transplant patients, are at an increased risk of developing cardiovascular disease. BNP measurement, as a biomarker of cardiovascular risk, has been recommended to this high-risk population. Plasma BNP levels were measured in 56 CKD children in either pre-dialysis stage, hemodialysis (HD) or renal transplant recipients (RTRs) and in 76 sex- and age-matched healthy controls. BNP levels were investigated in HD children, before and after the completion of their HD session. BNP levels in total CKD population, in pre-dialysis stage patients and on HD were significantly higher, compared to the respective controls. HD children had higher BNP levels compared to CKD patients in the pre-dialysis stage. Moreover, post-HD BNP concentration was slightly higher than pre-HD, with the difference being marginally statistically significant. BNP was positively correlated with eGFR, creatinine, cystatin-C and parathormone and negatively with albumin and 25-hydroxyvitamin D. A positive correlation between BNP concentration and the ratio of E/A in pulse-wave Doppler echocardiography was also observed. In conclusion, CKD pediatric patients, mainly those undergoing HD, have high plasma BNP levels which do not decrease after the HD session. This is indicative of a greater risk for future cardiovascular disease.

Water - A life-giving toxin - A nephrological oxymoron. Health consequences of water and sodium balance disorders. A review article

BACKGROUND

This article aims to reveal misconceptions about methods of assessment of hydration status and impact of the water disorders on the progression of kidney disease or renal dysfunction.

MATERIALS AND METHODS

The PubMed database was searched for reviews, meta-analyses and original articles on hydration, volume depletion, fluid overload and diagnostic methods of hydration status, which were published in English.

RESULTS

Based on the results of available literature the relationship between the amount of fluid consumed, and the rate of progression of chronic kidney disease, autosomal dominant polycystic kidney disease, and kidney stones disease was discussed. Selected aspects of the assessment of the hydration level in clinical practice based on physical examination, laboratory tests, and imaging are presented. The subject of in-hospital fluid therapy is discussed. Based on available randomized studies, an attempt was made to assess, which fluids should be selected for intravenous treatment.

CONCLUSIONS

There is some evidence for the beneficial effect of increased water intake in preventing recurrent cystitis and kidney stones, but there are still no convincing data for chronic kidney disease and autosomal dominant polycystic kidney disease. Further studies are needed to clarify the aforementioned issues and establish a reliable way to assess the volemia and perform suitable fluid therapy.

Serum NT-Pro-BNP versus Noninvasive Bedside Inotropic Index in Paediatric Shock: A Contest of Myocardial Performance in Response to Fluid Loading

Background

Mild elevation of serum amino-terminal pro-B-type natriuretic peptide (NT-pro-BNP) is associated with myocardial dysfunction. A significantly lower Smith-Madigan inotropic index (SMII) has been shown to accurately represent cardiac contractility among heart failure subjects. We aim to monitor the effect of fluid resuscitation on cardiac function among paediatric patients by measuring serum NT-pro-BNP and SMII.

Methods

This is an observational study on 70 paediatric shock patients. NT-pro-BNP and noninvasive bedside haemodynamic monitoring were done by using an ultrasonic cardiac output monitor (USCOM, USCOM, Sydney, Australia). The presence of cardiac diseases was excluded. SMII was obtained from the USCOM. An increase in the stroke volume index (SVI) of ≥15% indicates fluid responders. Measurements were taken before and after fluid loading.

Results

Preloading NT-pro-BNP and SMII category were significantly different between the fluid responsiveness group, p=0.001 and p=0.004, respectively. Higher median NT-pro-BNP (preloading NT-pro-BNP of 1175.00 (254.50-9965.00) ng/mL vs. 196.00 (65.00-509.00) ng/mL, p=0.002) was associated with fluid nonresponders (subjects >12 months old). Preloading NT-pro-BNP <242.5 ng/mL was associated with fluid responders (AUC: 0.768 (0.615-0.921), p=0.003), 82.1% sensitivity, and 68.7% specificity for subjects >12 years old. Delta NT-pro-BNP in fluid responders (15.00 (-16.00-950.00) ng/mL) did not differ from fluid nonresponders (505.00 (-797.00-1600.00) ng/mL), p=0.456. Postloading SMII >1.25 W·m^-2 was associated with fluid responders (AUC: 0.683 (0.553-0.813), p = 0.011), 61.9% sensitivity, and 66.7% specificity, but not preloading SMII. Fluid responders had a higher mean postloading SMII compared to nonresponders (1.36 ± 0.38 vs. 1.10 ± 0.34, p=0.006).

Conclusion

Higher NT-pro-BNP and lower SMII in the absence of cardiac diseases were associated with poor response to fluid loading. The SMII is affected by low preload conditions.

Early results using N-terminal pro-B-Type Natriuretic Peptide (pro-BNP) as a biomarker for the efficacy of secondary extension technique (SET) in improving myocardial function in dialysis patients with high flow fistulas

OBJECTIVES

The association of dialysis fistulas and heart failure is believed to be due to high cardiac output. N-terminal pro-B-Type Natriuretic Peptide (pro-BNP) which is secreted by the cardiac ventricles in response to excessive stretching of the myocytes has been used as a marker of heart failure with 90% sensitivity. We report our early experience using pro-BNP levels to test the efficacy of the novel 'secondary extension technique' (SET) in improving myocardial function by reducing fistula flow.

METHODS

11 patients with high fistula flows (>3000ml/m, all brachio-cephalic) and raised pro-BNP underwent SET between 2011 and 2015. SET involves extending the anastomosis from brachial to either proximal radial or ulnar arteries. We measured pro-BNP levels, fistula flow and clinical improvements both pre and post operatively.

RESULTS

SET resulted in a median (IQR) flow rate decrease of 57.9 (11.9) % which correlated with a fall in pro-BNP of 69.6 (39) %. 7 of the 11 patients in the series pro-BNP level returned to a normal value at average follow-up of 3 months post SET. All patients had HOF-related symptom resolution post-procedure and remained asymptomatic at last follow-up CONCLUSION: Our pilot data suggests that SET is an effective way of reducing fistula flow. It also shows that BNP may be a reliable biomarker in assessing the impact of the technique on cardiac function. These results warrant further investigation in the form of a definitive, multicentre study.

Body Fat Plays an Important Role in of Bioimpedance Spectroscopy-Based Dry Weight Measurement Error for Patients with Hemodialysis

Accurate dry weight (DW) estimation is important for hemodialysis patients. Although bioimpedance spectroscopy (BIS) is commonly used to measure DW, the BIS-based DW frequently differs from the clinical DW. We analyzed the characteristics of patients whose BIS-based DWs were over- and underestimated. In this retrospective cohort study, we evaluated 1555 patients undergoing maintenance hemodialysis in Chungnam National University Hospital. The gap (DWCP-BIS) was calculated by comparing the BIS and clinical DWs. We analyzed the clinical characteristics of patients with positive (n = 835) and negative (n = 720) gaps. Compared with other patients, the DWCP-BIS-positive group had higher extracellular water (ECW) level and extracellular/intracellular water index (E/I) and had lower weight, body mass index (BMI), lean tissue index (LTI), fat tissue index (FTI), fat mass (FAT), and adipose tissue mass (ATM). The DWCP-BIS-negative group exhibited elevated BMI, FTI, FAT, and ATM; however, it had lower height, ECW, and E/I. Linear regression analysis revealed that FAT significantly predicted DWCP accuracy. The clinical DW of patients with a low fat mass tended to be underestimated, while the clinical DW of patients with comparatively large fat reserves tended to be overestimated. These characteristics will aid in the reduction of BIS-based DW errors.

B-type natriuretic peptide levels and volume status in twice-weekly hemodialysis patients

Background

Twice-weekly hemodialysis (HD) could be regarded as an important part of incremental hemodialysis, volume status of this treatment model remains to be elucidated.

Methods

Patients undergoing regular twice-weekly or thrice-weekly hemodialysis in our unit on June 2015 were enrolled into the cohort study with an average of 2.02 years follow-up. Volume status of the subjects was evaluated by clinical characteristics, plasma B-type natriuretic peptide (BNP) levels and bioimpedance assessments with body composition monitor (BCM). Cox proportional hazards models and Kaplan–Meier analysis were used to compare patient survival between the two groups.

Results

Compared with patients on thrice-weekly HD, twice-weekly HD patients had significantly higher log-transformed BNP levels (2.54 ± 0.41 vs. 2.33 ± 0.49 pg/ml, p = 0.010). Overhydration (OH) and the ratio of overhydration to extracellular water (OH/ECW) in twice-weekly HD group were significantly higher than that of thrice-weekly HD (OH, 2.54 ± 1.42 vs. 1.88 ± 1.46, p = 0.033; OH/ECW, 0.17 ± 0.07 vs. 0.12 ± 0.08, p = 0.015). However, subgroup analysis of patients within 6 years HD vintage indicated that the two groups had similar hydration status. Multivariate Cox regression analysis showed that log-transformed BNP levels, serum albumin and diabetes status were predictors of mortality in hemodialysis patients. Kaplan–Meier survival analysis indicated that patients with BNP levels higher than 500 pg/ml had significantly worse survival compared with those with lower BNP levels (p = 0.014).

Conclusions

Twice-weekly hemodialysis patients had worse volume status than that of thrice-weekly HD patients especially for those with long-term dialysis vintage, BNP level was a powerful predictor of mortality 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.

A novel approach to dry weight adjustments for dialysis patients using machine learning

Background and aims

Knowledge of the proper dry weight plays a critical role in the efficiency of dialysis and the survival of hemodialysis patients. Recently, bioimpedance spectroscopy(BIS) has been widely used for set dry weight in hemodialysis patients. However, BIS is often misrepresented in clinical healthy weight. In this study, we tried to predict the clinically proper dry weight (DW_CP) using machine learning for patient’s clinical information including BIS. We then analyze the factors that influence the prediction of the clinical dry weight.

Methods

As a retrospective, single center study, data of 1672 hemodialysis patients were reviewed. DW_CP data were collected when the dry weight was measured using the BIS (DW_BIS). The gap between the two (Gap_DW) was calculated and then grouped and analyzed based on gaps of 1 kg and 2 kg.

Results

Based on the gap between DW_BIS and DW_CP, 972, 303, and 384 patients were placed in groups with gaps of <1 kg, ≧1kg and <2 kg, and ≧2 kg, respectively. For less than 1 kg and 2 kg of GapDW, It can be seen that the average accuracies for the two groups are 83% and 72%, respectively, in usign XGBoost machine learning. As Gap_DW increases, it is more difficult to predict the target property. As Gap_DW increase, the mean values of hemoglobin, total protein, serum albumin, creatinine, phosphorus, potassium, and the fat tissue index tended to decrease. However, the height, total body water, extracellular water (ECW), and ECW to intracellular water ratio tended to increase.

Conclusions

Machine learning made it slightly easier to predict DW_CP based on DW_BIS under limited conditions and gave better insights into predicting DW_CP. Malnutrition-related factors and ECW were important in reflecting the differences between DW_BIS and DW_CP.

Diagnostic performance of pulmonary ultrasonography and a clinical score for the evaluation of fluid overload in haemodialysis patients

INTRODUCTION

There is no feasible benchmark in daily routine to estimate the hydration status of haemodialysis patients, which is essential to their management.

OBJECTIVE

We performed a study in haemodialysis patients to assess the diagnostic performance of pulmonary ultrasound and clinical examination for the evaluation of fluid overload using transthoracic echocardiography as a gold standard.

METHODS

Thirty-one patients receiving chronic haemodialysis patients were included. Evaluation of hydration status was assessed weekly before haemodialysis sessions using clinical and Echo Comet Score from pulmonary ultrasound and transthoracic echocardiography (reference method).

RESULTS

Five patients had a transthoracic echocardiography overload. Compared with transthoracic echocardiography, the diagnostic performance of the clinical overload score has a sensitivity of 100%, a specificity of 77%, a positive predictive value of 50% and a negative predictive value of 100% with a κ of 0.79. Only orthopnoea (P=0.008), jugular turgor (P=0.005) and hepatic-jugular reflux (P=0.008) were significantly associated with transthoracic echocardiography overload diagnosis. The diagnostic performance of Echo Comet Score by pulmonary ultrasound has a sensitivity of 80%, a specificity of 58%, a positive predictive value of 26% and a negative predictive value of 94%. Ten patients (32.3%) had an increase of extravascular pulmonary water without evidence of transthoracic echocardiography or clinical overload.

CONCLUSIONS

Our clinical score has a convincing diagnostic performance compared to transthoracic echocardiography and could be easily used in daily clinical routine to adjust dry weight. The evaluation of the overload using pulmonary ultrasound seems poorly correlated with the overload evaluated by transthoracic echocardiography. Extravascular pulmonary water undetected by clinical examination and transthoracic echocardiography remains a parameter that requires further investigation.

Do Natriuretic Peptide Measurements Provide Insights into Management of End-Stage Renal Disease Patients Undergoing Dialysis?

PURPOSE OF REVIEW

Impaired renal function may affect natriuretic peptide levels through a variety of factors and mechanisms, such as high prevalence of concomitant vascular and myocardial diseases, reduced clearance, increased risk of volume overload, and different types and solute removal techniques in the setting of dialysis. Nevertheless, accumulating evidence suggests that natriuretic peptide testing may provide insights into management of patients with chronic kidney disease (CKD) and end-stage kidney disease (ESRD) on dialysis, as they have been shown to be independently associated with morbidity and mortality.

RECENT FINDINGS

Rising natriuretic peptide levels over time may identify CKD patients more likely to approach ESRD and requiring dialysis initiation. Moreover, serial natriuretic peptide measurements may also be helpful in guiding fluid management in ESRD patients on dialysis. However, since patients with CKD usually have significantly higher and more variable baseline levels of natriuretic peptides than those without CKD, traditional cut-off values may not be applicable, and individualized trajectories should be applied and interpreted in the clinical context. Routine clinical use natriuretic peptide testing in the CKD and ESRD settings still needs to be refined and individualized, yet their diagnostic and prognostic values can provide valuable insights into clinical trajectories and potential treatment responses.

Range of plasma brain natriuretic peptide (BNP) levels in hemodialysis patients at a high risk of 1-year mortality and their relationship with the nutritional status: a retrospective cohort study in one institute

Background

Brain natriuretic peptide (BNP) levels are used as a marker of heart failure, which is the leading cause of morbidity and mortality in dialysis patients. BNP levels increase as renal function declines. The range of BNP levels associated with satisfactory longevity in dialysis patients currently remains unknown.

Methods

In total, 660 patients receiving maintenance hemodialysis were enrolled. BNP levels were measured at the end of the year and in a follow-up to assess 1-year mortality between 2008 and 2012. Patients were divided into six groups according to BNP levels: < 50 (reference), 50 to < 100, 100 to < 300, 300 to < 500, 500 to < 1000, and ≥ 1000 pg/mL. One-year mortality at each BNP level was analyzed using Cox’s proportional hazards model after adjustments for confounding factors.

Results

During the follow-up period, 78 (11.8%) deaths were recorded. After adjustments for confounding factors, such as gender, age, hemodialysis vintage, and primary disease, the risk of 1-year mortality was significantly high with BNP levels of 500 to < 1000 (hazard ratio [HR] 3.010; 95% confidence interval [CI] 1.065–10.729; P = 0.037) and more than 1000 pg/mL (HR 5.291; 95%CI 2.014–18.170; P = 0.0003). After adjustments for Kt/V, the risk of 1-year mortality was also significantly high with BNP levels of 500 to < 1000 (HR 3.045; 95%CI 1.065–10.929; P = 0.037) and more than 1000 pg/mL (HR 5.221; 95%CI 1.943–18.165; P = 0.0006). Following further adjustments for nutritional factors, such as albumin levels, total cholesterol levels, the normalized protein catabolic rate (nPCR), body mass index (BMI), and percent creatinine generation rate (%CGR), BNP levels of 500–1000 (HR 1.990; 95%CI 0.639–7.570; P = 0.244), and more than 1000 pg/mL (HR 2.100; 95%CI 0.663–8.105; P = 0.213) were no longer risk factors.

Conclusion

In dialysis patients, a BNP level ≥ 500 pg/mL is a risk factor for 1-year mortality. The risk associated with high BNP levels is reduced by nutritional factors, which suggests a relationship between high BNP levels and the nutritional status. In conclusion, efforts are needed to maintain BNP levels at lower than 500 pg/mL and improve the nutritional status.

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

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

TRIAL REGISTRATION

ClinicalTrials.org, NCT01509937. Registered 13 January 2012.

Association between Serum N-Terminal Pro-Brain Natriuretic Peptide Concentration and Left Ventricular Dysfunction and Extracellular Water in Continuous Ambulatory Peritoneal Dialysis Patients

Background

This study investigated the association between serum N-terminal pro-brain natriuretic peptide (NT-pro-BNP) levels and extracellular water (ECW%) and left ventricular (LV) dysfunction in continuous ambulatory peritoneal dialysis (CAPD) patients.

Methods

The study involved 30 stable CAPD patients: 14 males, 16 females; mean age 52 ± 14 years; mean CAPD duration 34 ± 12 months; 12 with diabetes mellitus (DM) and 18 non-DM. Serum NT-pro-BNP levels were determined using electrochemiluminescence immunoassay. Baseline echocardiography was performed using a Hewlett-Packard Sonos 1000 (Andover, Massachusetts, USA) device equipped with a 2.25-MHz probe, allowing M-mode, two-dimensional, and pulsed Doppler measurements. Left ventricular mass index (LVMI) was calculated according to the Penn formula. A multifrequency bioimpedance analyzer was used; ECW% was calculated as a percentage of total body water and was considered the index of volume load.

Results

( 1 ) Serum NT-pro-BNP level, ECW%, LVMI, and LV ejection fraction in CAPD patients were 3924 (240 – 74460) pg/mL, 36.7% ± 2.2%, 158 ± 48 g/m2, and 60.5% ± 11.2%, respectively. ( 2 ) Patients were divided into three tertiles (10 patients each) according to their serum NT-pro-BNP concentration [1st tertile 1168 (240 – 2096), 2nd tertile 4856 (2295 – 20088), 3rd tertile 35012 (20539 – 74460) pg/mL]. The tertiles did not differ significantly in terms of age, sex, presence of DM, body mass index, or PD duration. Patients in the 3rd tertile (highest serum NT-pro-BNP concentration) had the highest LVMI (126 ± 45 vs 160 ± 41 vs 200 ± 23 g/m2 for 1st, 2nd, 3rd tertiles, respectively) and the lowest LV ejection fraction (66% ± 11% vs 62% ± 6% vs 55% ± 9%). ECW% did not differ significantly between tertiles (35.5% ± 2.0% vs 37.5% ± 2.0% vs 36.5% ± 2.0%). ( 3 ) In CAPD patients, serum NT-pro-BNP levels correlated positively with LVMI ( r = 0.628, p = 0.003) and negatively with LV ejection fraction ( r = –0.479, p = 0.033). Serum NT-pro-BNP levels did not correlate with ECW% ( r = 0.227, p = 0.25). ( 4 ) Stepwise regression analysis showed that LV ejection fraction (b = -0.610, p = 0.015) and LVMI (b = 0.415, p = 0.007) were independently associated with the serum NT-pro-BNP concentration.

Conclusions

There was no link between ECW% and serum NT-pro-BNP concentration. Thus, serum NT-pro-BNP levels may not provide objective information with respect to pure hydration status in CAPD patients. In contrast, serum NT-pro-BNP levels were linked to LVMI and LV ejection fraction in CAPD patients. Therefore, while the serum NT-pro-BNP concentration might not be a useful clinical marker for extracellular fluid volume load, it appears useful for evaluating LV hypertrophy and LV dysfunction in CAPD patients.

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.

Brain natriuretic peptide reflects individual variation in hydration status in hemodialysis patients

Introduction: Fluid management in hemodialysis patients is a controversial topic. Brain natriuretic peptide (BNP) is secreted from the heart in response to volume overload, and may be a marker of overhydration in hemodialysis patients. Our aim was to investigate the correlation between BNP and overhydration in a cohort of hemodialysis patients, and to find out whether BNP and overhydration correlate in repeated measurements within individuals with elevated BNP.

Methods: The study was prospective, observational, and had a cross‐sectional part and a longitudinal follow‐up. The distribution of BNP was investigated in a cohort of 64 hemodialysis patients. Blood samples and bioimpedance spectroscopy measurements were performed before midweek dialysis. Subsequently, 11 study participants with elevated BNP concentrations (>500 pg/mL) were assessed in another nine dialysis sessions each. These individuals also had their cardiac function and heart rate variability (HRV) examined.

Findings: BNP was above 500 pg/mL in 38% of the participants, and correlated positively with overhydration (r_s = 0.381), inflammation and malnutrition, but not with systolic blood pressure. In comparison to participants with BNP below 500 pg/mL, participants with elevated BNP were older, had lower muscle strength, lower bodyweight and lower levels of hemoglobin and albumin. Echocardiography revealed cardiac anomalies in all 11 participants in the longitudinal follow‐up, and HRV, as measured by SDNN, was pathologically low. In repeated measurements, the between‐individuals variation of BNP in relation to overhydration was greater (SD = 0.581) than the within‐person variation (SD = 0.285).

Discussion: BNP correlates positively to overhydration, malnutrition, and inflammation. In a subgroup of patients with elevated BNP, who are mainly elderly and frail, BNP reflects individual variation in hydration status, and hence seems to be a modifiable marker of overhydration. These data suggest that BNP is best applied for measuring changes in hydration status within an individual over time.

The interaction between N-terminal pro-brain natriuretic peptide and fluid status in adverse clinical outcomes of late stages of chronic kidney disease

Introduction

Fluid overload is one of the major characteristics and complications in patients with chronic kidney disease (CKD). N-terminal pro-brain natriuretic peptide (NT-proBNP) is related to fluid status and fluid distribution. The aim of this study is to investigate the interaction between NT-proBNP and fluid status in adverse clinical outcomes of late stages of CKD.

Methods

We enrolled 239 patients with CKD stages 4–5 from January 2011 to December 2011 and followed up until June 2017. Fluid status was presented as hydration status (HS) value measured by body composition monitor, while HS>7% was defined as fluid overload. Clinical outcomes included renal outcomes (commencing dialysis and estimated glomerular filtration rate decline>3 ml/min/1.73 m²/year), all-cause mortality and major adverse cardiovascular events (MACEs).

Results

During a mean follow-up of 3.3±2.0 years, 129(54.7%) patients commenced dialysis, 88(37.3%) patients presented rapid renal function decline, and 48(20.3%) had MACEs or died. All patients were stratified by HS of 7% and the median of plasma NT-proBNP. The adjusted risks for commencing dialysis was significantly higher in patients with high plasma NT-proBNP and HS>7% compared to those with low plasma NT-proBNP and HS≦7%. There was a significant interaction between plasma NT-proBNP and HS in commencing dialysis (P-interaction = 0.047). Besides, patients with high plasma NT-proBNP and HS>7% had greater risks for MACEs or all-cause mortality than others with either high plasma NT-proBNP or HS>7%.

Conclusion

NT-proBNP and fluid overload might have a synergistic association of adverse clinical outcomes in patients with late stages of CKD.

Serum nitric oxide level correlates with serum brain natriuretic peptide and whole blood viscosity in hemodialysis patients

BACKGROUND

Nitric oxide (NO) is tonically synthesized by the vascular endothelium and known as a marker of vasodilatation and blood flow. As NO has a critical role in hemodynamics, NO may be associated with other hemodynamics-related factors including atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP) and whole blood viscosity (WBV). It has been reported that serum NO level increased in patients undergoing hemodialysis. However, there are few reports about the relationship between NO and hemodynamic parameters in hemodialysis patients.

OBJECTIVE

We investigated the associations between serum levels of NO and other hemodynamics-related factors such as ANP, BNP and WBV in patients with hemodialysis.

METHODS

NO, ANP, and BNP levels before hemodialysis were measured using ELISA method. We measured WBV in pre- and post-dialysis.

RESULTS

Mean serum levels of NO, ANP, and BNP were 13.97 ± 10.34 μg/mL, 198.85 ± 61.56 pg/mL, and 1233.32 ± 280.81 pg/mL, respectively in patients with hemodialysis. The mean WBV values at shear rates of 1, 5, and 300 s^-1 for pre-dialyses were 168.5 ± 62.5, 76.9 ± 20.6, and 33.3 ± 3.8 mP, respectively. Serum NO level was positively correlated with WBV at shear rates of 1, 5, and 300 s^-1 at pre- and post-hemodialysis. There is a correlation between serum nitrite levels and the change of SBV during hemodialysis. Serum nitrite levels correlated with the serum BNP levels. ANP levels have a negative correlation with pre-dialytic WBV. However, BNP levels did not correlate with WBV during hemodialysis.

CONCLUSIONS

WBV is linked to an imbalance in serum vasoactive substances in hemodialysis patients and can cause significant hemodynamic disturbance.

Clinical usefulness of bioimpedance analysis for assessing volume status in patients receiving maintenance dialysis

Chronic volume overload is associated with left ventricular hypertrophy and high cardiovascular mortality in patients undergoing dialysis. Therefore, estimating body fluid status is important in these patients. However, most dry-weight assessments are still performed clinically, while attempts have been made to measure the volume status and dry weight of patients undergoing dialysis using bioimpedance analysis (BIA). BIA uses the electrical properties of the human body to alternate current flow and measures resistance values to estimate body water content and composition. BIA is divided into single-frequency BIA, multi-frequency BIA, and bioimpedance spectroscopy (BIS) according to the number of frequencies used, and into whole-body and segmental BIA according to whether or not the whole body is divided into segments. Extracellular water (ECW), intracellular water, and total body water (TBW) contents can be measured with BIA. Dry weight can be estimated by measuring the volume overload of the patient through the ECW/TBW and ECW-to-body weight ratios. Other estimation methods include the normovolemia/hypervolemia slope method, a resistance-reactance (RXc) graph, overhydration measurements using a body composition monitor, and calf BIS. In this review, we will examine the principles of BIA, introduce various volume status measurement methods, and identify the optimal method for patients undergoing dialysis.

Intradialytic Hypotension as an Independent Risk Factor for Long-Term Mortality in Maintaining Hemodialysis Patients: A 5-Year Follow-Up Cohort Study

AIMS

This study aimed to assess risk factors of intradialytic hypotension (IDH) and the association of prognosis and IDH among maintenance hemodialysis (MHD) patients.

METHODS

Among 293 patients, 117 were identified with IDH (more than 4 hypotensive events during 3 months). The association between IDH and survival was evaluated.

RESULTS

The incidence of IDH was 39.9%. Age, ultrafiltration rate, N-terminal pro-B-type natriuretic peptide (NT-proBNP), albumin, β2-microglobulin (β2MG), and aortic root inside diameter (AoRD) were independently associated with IDH. During the 5-year follow-up, 84 patients died with a mortality rate 5.2 per 100 person-year. IDH-prone patients had a higher all-cause mortality rate. IDH and left ventricular mass index were independent risk factors for death (HR 1.655, 95% CI 1.061-2.580; HR 1.008, 95% CI 1.001-1.016).

CONCLUSION

IDH is an independent risk factor for long-term mortality in MHD patients. Patients with older age, high ultrafiltration rate, high level of serum NT-proBNP and β2MG, hypoalbuminemia, and shorter AoRD are at high risk of IDH.

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

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

Cardiac biomarkers in dialysis

Cardiovascular disease is the major cause of death, accounting for approximately 40 percent of all-cause mortality in patients receiving either hemodialysis or peritoneal dialysis. Cardiovascular risk stratification is an important aspect of managing dialysis patients as it enables early identification of high-risk patients, so therapeutic interventions can be optimized to lower cardiovascular morbidity and mortality. Biomarkers can detect early stages of cardiac injury so timely intervention can be provided. The B-type natriuretic peptides (Brain Natriuretic peptide [BNP] and N-terminal pro-B-type natriuretic peptide [NT-proBNP]) and troponins have been shown to predict mortality in dialysis patients. Suppression of tumorigenicity 2 (ST2) and galectin-3 are new emerging biomarkers in the field of heart failure in both the general and dialysis populations. This article aims to discuss the current evidence regarding cardiac biomarker use to diagnose myocardial injury and monitor the risk of major adverse cardiovascular events in patients undergoing dialysis.

Clinical Significance of the Edema Index in Incident Peritoneal Dialysis Patients

Background

Proper monitoring for volume overload is important to improve prognosis in peritoneal dialysis (PD) patients. The association between volume status and residual renal function (RRF) remains an unresolved issue. The aim of the present study was to evaluate the association between the edema index and survival or RRF in incident PD patients.

Patients and Methods

We identified all adults who underwent PD. The edema index was defined as the ratio of extracellular fluid to total body fluid. Participants with available data regarding survivorship or non-survivorship during the first year after PD initiation were included in the area under the receiver operating characteristic curve analysis. The cutoff value of the edema index for 1-year mortality was >0.371 in men and >0.372 in women. Participants were divided into two groups according to the cutoff value of their baseline edema indices: High (>cutoff value) and Low (≤cutoff value). Survivors during the first year after PD initiation were divided into two groups according to the initial and 1-year edema index: Non-improvement (maintenance of criteria in the initial Low group during the year) and Other (all participants except those in the Non-improvement group).

Results

In total, 631 patients were enrolled in the present study. The cutoff value of the edema index for 1-year mortality was >0.371 in men and >0.372 in women. The respective mean initial RRF values (mL·min^-1·1.73 m^-2) in the Low and High groups, respectively, were 4.88 ± 4.09 and 4.21 ± 3.28 in men (P = 0.108), and 3.19 ± 2.57 and 2.98 ± 2.70 in women (P = 0.531). There were no significant differences between groups in either sex. The respective mean RRF values at 1 year after PD initiation in the Low and High groups, respectively, were 3.56 ± 4.35 and 2.73 ± 2.53 in men, and 2.80 ± 2.36 and 1.85 ± 1.51 in women. RRF at 1 year after PD initiation was higher in the Low group than in the High group (men: P = 0.027; women: P = 0.001). In men, the cumulative 5-year survival rates were 78.7% and 46.2% in the Low and High groups, respectively, whereas in women, rates were 77.2% and 58.8% in the Low and High groups, respectively. For survivors during the first year after PD initiation, the Non-improvement group was associated with a poor survival rate compared with the Other group for both sexes.

Conclusion

A high edema index was associated with mortality in incident PD patients at baseline and follow-up. The edema index may be used as a new marker for predicting mortality in PD patients.

The role of natriuretic peptides in volume assessment and mortality prediction in Haemodialysis patients

Background

Maintaining optimal fluid balance is essential in haemodialysis (HD) patients but clinical evaluation remains problematic. Other technologies such as bioimpedance are emerging as valuable adjuncts. This study was undertaken to explore the potential utility of the natriuretic peptides – atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) in the assessment of fluid status and cardiovascular risk in this setting.

Methods

This was a cross-sectional study carried out in an unselected cohort of 170 prevalent HD patients. Volume status was assessed by clinical parameters – the presence or absence of peripheral oedema, raised jugular venous pressure and basal lung crepitations; by extracellular fluid volume (ECFV) status determined by whole body bioimpedance; and by serum levels of BNP and ANP (pre- and post –dialysis). The relationships of ANP and BNP levels to clinical and bioimpedance parameters of volume status was determined. Patients were followed up for 5 years to assess the relationship of natriuretic peptide levels to mortality.

Results

Bioimpedance estimates of ECFV expansion (>105 % of ideal ECFV) was present in 52 % of patients pre-dialysis. A significant proportion (21 %) of pre-dialysis patients had a depleted ECFV (<95 % of ideal ECFV) pre-dialysis. The situation was reversed post-dialysis. A raised JVP >3 cm was the most reliable clinical sign of ECFV expansion inferred from bioimpedance measurements and natriuretic peptide levels. The vast majority of patients with this sign also had lung crepitations or peripheral oedema or both. BNP was a stronger predictor of ECFV expansion than either pre- or post-dialysis ANP. BNP was also a stronger predictor of five-year survival.

Conclusion

Serum levels of BNP have a strong relationship to both volume status and survival in HD patients. We found no clear role for measurement of ANP, though changes in blood levels may be a sensitive indicator of acute changes in volume status. Whether monitoring levels of these peptides has a role in the management of volume status and cardiovascular risk requires further study.

N-terminal pro-B-type natriuretic peptide variability in stable dialysis patients

BACKGROUND AND OBJECTIVES

Monitoring N-terminal pro-B-type natriuretic peptide (NT-proBNP) may be useful for assessing cardiovascular risk in dialysis patients. However, its biologic variation is unknown, hindering the accurate interpretation of serial concentrations. The aims of this prospective cohort study were to estimate the within- and between-person coefficients of variation of NT-proBNP in stable dialysis patients, and derive the critical difference between measurements needed to exclude biologic and analytic variation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Fifty-five prevalent hemodialysis and peritoneal dialysis patients attending two hospitals were assessed weekly for 5 weeks and then monthly for 4 months between October 2010 and April 2012. Assessments were conducted at the same time in the dialysis cycle and entailed NT-proBNP testing, clinical review, electrocardiography, and bioimpedance spectroscopy. Patients were excluded if they became unstable.

RESULTS

This study analyzed 136 weekly and 113 monthly NT-proBNP measurements from 40 and 41 stable patients, respectively. Results showed that 22% had ischemic heart disease; 9% and 87% had left ventricular systolic and diastolic dysfunction, respectively. Respective between- and within-person coefficients of variation were 153% and 27% for weekly measurements, and 148% and 35% for monthly measurements. Within-person variation was unaffected by dialysis modality, hydration status, inflammation, or cardiac comorbidity. NT-proBNP concentrations measured at weekly intervals needed to increase by at least 46% or decrease by 84% to exclude change due to biologic and analytic variation alone with 90% certainty, whereas monthly measurements needed to increase by at least 119% or decrease by 54%.

CONCLUSIONS

The between-person variation of NT-proBNP was large and markedly greater than within-person variation, indicating that NT-proBNP testing might better be applied in the dialysis population using a relative-change strategy. Serial NT-proBNP concentrations need to double or halve to confidently exclude change due to analytic and biologic variation alone.

Adding "hemodynamic and fluid leads" to the ECG. Part I: the electrical estimation of BNP, chronic heart failure (CHF) and extracellular fluid (ECF) accumulation

OBJECTIVES

In primary care the diagnosis of CHF and ECF accumulation is no triviality. We aimed to predict plasma BNP, CHF and ECF accumulation with segmental impedance spectroscopy while using and extending the electrodes of the conventional electrocardiography.

METHODS

Three combined multiple electrodes were added to the 15 lead ECG for segmental impedance spectroscopy and for measuring the maximal rate of segmental fluid volume change with heart action at the thorax and the legs. The obtained signals were analyzed by partial correlation analyses in comparison with plasma BNP, CHF classes, ejection fraction by echocardiography and cardiac index by double gas re-breathing. 119 subjects (34 healthy volunteers, 50 patients with CHF, NYHA classes II to IV and 35 patients without CHF) were investigated.

RESULTS

The maximal rate of volume change with heart action at the thorax and at the legs, as well as the ECF/ICF ratio at the legs contribute equally and independently to the prediction of BNP and heart failure in an unknown test sample of 49 patients (multiple r=0.88, p<0.001). The ROC-curve for the predicted plasma BNP>400 pg/ml gave an AUC=0.93. The absence or the presence of heart failure could be predicted correctly by a binomial logistic regression in 92.9 and 87.5% of cases, respectively.

CONCLUSION

The methodology, which is based on inverse coupling of BNP release and of maximal blood acceleration and on sensitive detection of ECF overload, could enable the diagnosis of CHF with useful sensitivity and specificity while writing a routine-ECG.

B-type natriuretic peptide predicts an ischemic etiology of acute heart failure in patients with stage 4-5 chronic kidney disease

OBJECTIVES

The non-invasive differentiation of ischemic and non-ischemic acute heart failure (AHF) not resulting from acute myocardial infarction is difficult and has therapeutic and prognostic implications. The aim of this study was to assess whether plasma B-type natriuretic peptide (BNP) can identify ischemic etiology in patients with stage 4-5 chronic kidney disease (CKD) presenting with AHF.

DESIGN AND METHODS

We prospectively analyzed 61 patients. The diagnosis of ischemic AHF was confirmed by coronary angiography or stress myocardial perfusion imaging. Plasma levels of BNP were measured at admission (BNP1) and 48 h after admission (BNP2).

RESULTS

The mean age of the study patients was 67 years. In these patients, 70.5% had diabetes and 47.5% had dialysis-dependent CKD; 28 of these patients (45.9%) had an ischemic etiology with significantly higher concentrations of BNP1 and BNP2 than did patients without ischemia. The area under the receiver operating characteristic curve was 0.755 (P=0.001) for BNP1 and 0.868 (P<0.001) for BNP2 to detect ischemic etiology of AHF. Plasma BNP1 >2907 ng/L (odds ratio [OR], 10.9; 95% confidence interval [CI] 2.5-48.4; P=0.002) and BNP2 >2322 ng/L (OR 93.1, 95% CI 7.0-1238.7; P=0.001) were independently associated with an ischemic etiology of AHF.

CONCLUSIONS

Plasma BNP may represent a clinically useful non-invasive tool for identification of ischemic etiology of AHF in patients with stage 4-5 CKD.

B-type natriuretic peptide and prognosis of end-stage renal disease: a meta-analysis

Background

The prognostic importance of B-type natriuretic peptide (BNP) or N-terminal pro BNP (NT-proBNP) in patients with end-stage renal disease (ESRD) remains controversial.

Methodology/Principal Findings

We conducted an unrestricted search from the MEDLINE and EMBASE in all languages that were published between 1966 and Augest2013. Twenty-seven long-term prospective studies met our inclusion criterias. From the pooled analysis, elevated BNP/NT-proBNP was significantly associated with increased all cause mortality [odds ratio (OR), 3.85; 95% CI, 3.11 to 4.75], cardiovascular mortality (OR, 4.05; 95% CI, 2.53 to 6.84), and cardiovascular events (OR, 7.02; 95% CI, 2.21 to 22.33). The funnel plot showed no evidence of publication bias. The corresponding pooled positive and negative likelihood ratio for prediction of all cause mortality were 1.86 (95% CI, 1.66 to 2.08) and 0.48 (95% CI, 0.42 to 0.55), respectively.

Conclusions/Significance

BNP/NT-proBNP is a promising prognostic tool to risk-stratify the patients with ESRD. Further investigations are warranted to elucidate the specific pathogenic mechanisms and the impact of other potential prognostic factors.

[Fluid overload and arterial hypertension in hemodialysis patients]

The water sodium overload is a factor of morbi-mortality and its treatment is one of the markers of adequacy of the hemodialysis treatment. Its first clinical assessment was improved by tools such as echocardiography and ultrasonography of the inferior vena cava, the per-dialytic curve of plasma volume, measuring BNP or proBNP and by impedancemetry. The combination of the evaluation of these parameters and of the clinical situation allows one to assess the extracellular overload, the state of the blood volume and the potential of plasma refilling. The latter is a key factor of the per-dialytic hemodynamic tolerance. It is itself a determining factor in weight can be achieved at the end of the session. Getting the "dry" weight can require modifications of the prescriptions of the hemodialysis sessions, a filling by albumin even a drugs support. Finally, the overload treatment is the central part of the treatment of arterial hypertension, which has to benefit however often from antihypertensive treatment the profit of which is demonstrated.

Significance of interdialytic weight gain versus chronic volume overload: consensus opinion

Predialysis volume overload is the sum of interdialytic weight gain (IDWG) and residual postdialysis volume overload. It results mostly from failure to achieve an adequate volume status at the end of the dialysis session. Recent developments in bioimpedance spectroscopy and possibly relative plasma volume monitoring permit noninvasive volume status assessment in hemodialysis patients. A large proportion of patients have previously been shown to be chronically volume overloaded predialysis (defined as >15% above 'normal' extracellular fluid volume, equivalent to >2.5 liters on average), and to exhibit a more than twofold increased mortality risk. By contrast, the magnitude of the mortality risk associated with IDWG is much smaller and only evident with very large weight gains. Here we review the available evidence on volume overload and IDWG, and question the use of IDWG as an indicator of 'nonadherence' by describing its association with postdialysis volume depletion. We also demonstrate the relationship between IDWG, volume overload and predialysis serum sodium concentration, and comment on salt intake. Discriminating between volume overload and IDWG will likely lead to a more appropriate management of fluid withdrawal during dialysis. Consensually, the present authors agree that this discrimination should be among the primary goals for dialysis caretakers today. In consequence, we recommend objective measures of volume status beyond mere evaluations of IDWG.

B-type natriuretic peptide is not a volume marker among patients on hemodialysis

BACKGROUND

Although the cardiac biomarker B-type natriuretic peptide (BNP) is strongly related to mortality in end-stage renal disease (ESRD), whether it is a predictor of weight change or blood pressure (BP) response upon probing dry weight among hypertensive hemodialysis patients remains unknown. The purpose of this study was to examine among people with hypertension on hemodialysis whether BNP is a biomarker of excess volume.

METHODS

Hypertensive hemodialysis patients (n = 150) were randomized to a control group (n = 50) or an ultrafiltration group (n = 100) and followed up for 30 dialysis treatments. After a baseline run-in of six treatments, those assigned to the ultrafiltration group had dry weight probed over 8 weeks. Forty-four-hour interdialytic ambulatory BP and predialysis BNP were measured at the end of run-in period, at 4 weeks and at 8 weeks.

RESULTS

The median BNP concentration was 93 pg/mL (interquartile range 31-257 pg/mL). The magnitude of decline in the BNP depended on the baseline concentration of BNP, but did not require probing dry weight or weight loss. No relationship existed between decline in postdialysis weight upon probing dry weight and baseline BNP. Furthermore, reduction in the BNP was not required for decline in postdialysis weight. Predialysis log BNP modestly predicted ambulatory systolic and pulse pressure independently of other risk factors. No relationship was found between decline in BP upon probing dry weight and baseline BNP. Upon probing dry weight, reduction in BNP was not required for decline in systolic ambulatory BP.

CONCLUSION

Taken together, these data suggest that among hypertensive patients on hemodialysis BNP is not a volume marker.

Volume estimation in dialysis patients: the concordance of brain-type natriuretic peptide measurements and bioimpedance values

Correct estimation of the dialysis patients' hydration status remains an important clinical challenge. Bioimpedance measurements have been validated by various physiological tests, and the use of brain-type natriuretic peptide (BNP) has been validated by inferior vena cava diameter measurements. This is an observational cohort study that evaluated the correspondence between bioimpedance-measured overhydration percentage (OH%) and BNP. We measured predialysis OH% by bioimpedance apparatus (Body Composition Monitor) and BNP by microparticle enzyme-linked immunoassay in 41 prevalent stable hemodialysis patients, 19 (46%) women, aged 58.9 ± 14.5 years. The cohort's average BNP was 2694 ± 3278 pg/mL and 10 (24.4%) of these 41 patients had BNP < 500 pg/mL (average 260.7 ± 108.5). The OH% was 8.5 ± 7.0% among those with a BNP < 500 pg/mL, while the rest of the population had an OH% of 21.4 ± 8.0%, corresponding to excess volumes of 1.6 ± 1.3 and 4.4 ± 3.8 L, respectively. The OH% vs. BNP relationship was best described by the exponential regression of y = 216.4e(0.097x) , predicting a BNP of 216.4 pg/mL at 0% overhydration status (r 0.61). Receiver-operating curves revealed an area under the curve of 0.885 for BNP when the OH% was set ≥15% of overhydration and an area under the curve of 0.918 for OH% when the BNP was set ≥500 pg/mL for being abnormal. We conclude that in our cohort there was a high degree of correspondence between these two tests with an exponential relationship between the measurements.

Biomarkers in hemodialysis patients

Patients with chronic kidney disease (CKD) are, compared to the general population, at higher risk of cardiovascular disease (CVD), including sudden death, coronary artery disease (CAD), congestive heart failure (HF), stroke, and peripheral artery disease. The presence of CVD is independently associated with kidney function decline. Renal insufficiency is a strong and independent predictor of mortality in patients with different CKD stages. The interplay of traditional and nontraditional risk factors is complex such that risk factor profiles are different in CKD patients. Seemingly, paradoxical associations between traditional risk factors and cardiovascular outcome complicate efforts to identify real cardiovascular etiology in these patients. Additional tools are often required to aid clinical assessment of cardiovascular risk. Recently, a number of cardiovascular biomarkers were identified as predictors of outcome in CVD. These may be used to guide early diagnosis and therapy for CVD or may predict outcome in CKD. This review focuses on the potential diagnostic and prognostic use of some important new biomarkers including brain natriuretic peptide (BNP), cardiac troponins (cTns), inflammatory markers, adhesion molecules, and asymmetric dimethylarginine (ADMA) in CKD as well as those patients with end-stage renal failure.

Plasma BNP, a useful marker of fluid overload in hospitalized hemodialysis patients

Hospitalization for intercurrent illness frequently disrupts the nutritional status of hemodialysis (HD) patients and jeopardizes the dry weight prescription. We report in this study the evolution of brain natriuretic peptide (BNP), blood pressure and body weight in hospitalized patients and the relationship between BNP plasma level and nutritional and inflammation parameters. We have studied 42 patients requiring hospitalization (F/M: 18/24; 72.5 ± 12.5 years old; 19/42 with diabetes). The plasma BNP levels at baseline, during hospitalization (BNP-Hosp), and in the recovery phase were compared. Predialysis and postdialysis blood pressure and postdialysis body weight were recorded and compared. BNP-Hosp increased significantly when compared with BNP levels at baseline, from 421 ± 647.2 pg/mL to 1584 ± 1584.4 pg/mL (P < 0.0001). Brain natriuretic peptide decreased from 1223 ± 1342.1 pg/mL during hospitalization to 616 ± 892.1 pg/mL after discharge (P = 0.005). The BNP-Hosp was positively correlated with C-reactive protein (P = 0.003) and negatively correlated with serum prealbumin (P = 0.0001) and albumin (P = 0.0001). The postdialysis body weight prescription decreased from 71.0 ± 15.7 kg at baseline to 70.5 ± 15.4 kg during hospitalization and to 67.8 ± 14.4 kg 4 months after discharge (P = 0.0032). Our study displays clearly the significant changes of plasma BNP levels occurring during intercurrent events. Fluid overload triggered by inflammation-associated catabolism and the lag time for dry weight adjustment is the cause of this finding. Hence, plasma BNP level may be used as a marker of fluid overload in patients with intercurrent events and may allow efficient dry weight adjustment. We cannot rule out an effect of inflammation on BNP synthesis.

Fluid overload assessment and management in heart failure patients

Heart failure is a syndrome in which myocardial function is incapable of providing for normal physiologic needs. In the acute care setting, cardiac dysfunction primarily manifests with volume perturbations and presents with signs and symptoms of vascular congestion. Thus, in acute heart failure volume assessment is crucial in diagnosing and improving the prognosis. Also, goal-directed therapy relies on accurate volume assessment to minimize the adverse outcomes of inappropriate, ineffective, or excessive diuresis. Currently, in most institutions clinical methods of volume assessment are the mainstay. However, these methods are highly dependent on the practitioners' skill level. In fact, there is a high variability between experienced physicians when assessing volume. As adjuncts, objective methods of volume assessment are being developed and used such as natriuretic peptides, bioimpedance analysis, and imaging.