The Effect of Fluid Overload on Clinical Outcome in Southern Chinese Patients Undergoing Continuous Ambulatory Peritoneal Dialysis

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BACKGROUND

Fluid overload is frequently present in dialysis patients and one of the important predictors of patient outcome. This study aimed to investigate the influence of fluid overload on all-cause mortality and technique failure in Southern Chinese continuous ambulatory peritoneal dialysis (CAPD) patients. ♦

METHODS

This was a post hoc study from a cross-sectional survey originally designed to investigate the prevalence and associated risk factors of fluid overload defined by bioimpedance analysis (BIA) in CAPD patients from January 1, 2008, to December 31, 2009. All 307 CAPD patients completing the original study were followed up until December 31, 2012. ♦

RESULTS

With a median follow-up period of 38.4 (19.2 - 47.9) months, 52 patients died. Patients with fluid overload (defined by extracellular water/total body water [ECW/TBW] ≥ 0.40) had a significantly higher peritonitis rate (0.016 vs 0.011 events/month exposure, p = 0.018) and cerebrovascular event rate (3.9 vs 1.1 events/100 patient years, p = 0.024) than the normal hydrated patients. Moreover, the results showed a significant rising of all-cause mortality (log-rank test = 5.59, p = 0.018), and a trend of increasing cardiovascular disease (CVD) mortality (log-rank test = 2.90, p = 0.089) and technique failure (log-rank test = 3.78, p = 0.052) in the patients with fluid overload. Fluid overload independently predicted all-cause mortality (hazard ratio [HR] = 12.98, 95%, confidence interval [CI] = 1.06 - 168.23, p = 0.042) and technique failure (HR = 13.56, 95% CI = 2.53 - 78.69, p = 0.007) in CAPD patients after adjustment for confounders. ♦

CONCLUSIONS

Fluid overload defined by BIA was an independent predictor for all-cause mortality and technique failure in CAPD patients. Continuous ambulatory peritoneal dialysis patients with fluid overload had a higher peritonitis rate, cardiovascular event rate, and poorer clinical outcome than those patients with normal hydration.

ISPD Cardiovascular and Metabolic Guidelines in Adult Peritoneal Dialysis Patients Part I - Assessment and Management of Various Cardiovascular Risk Factors

Cardiovascular disease contributes significantly to the adverse clinical outcomes of peritoneal dialysis (PD) patients. Numerous cardiovascular risk factors play important roles in the development of various cardiovascular complications. Of these, loss of residual renal function is regarded as one of the key cardiovascular risk factors and is associated with an increased mortality and cardiovascular death. It is also recognized that PD solutions may incur significant adverse metabolic effects in PD patients. The International Society for Peritoneal Dialysis (ISPD) commissioned a global workgroup in 2012 to formulate a series of recommendations regarding lifestyle modification, assessment and management of various cardiovascular risk factors, as well as management of the various cardiovascular complications including coronary artery disease, heart failure, arrhythmia (specifically atrial fibrillation), cerebrovascular disease, peripheral arterial disease and sudden cardiac death, to be published in 2 guideline documents. This publication forms the first part of the guideline documents and includes recommendations on assessment and management of various cardiovascular risk factors. The documents are intended to serve as a global clinical practice guideline for clinicians who look after PD patients. The ISPD workgroup also identifies areas where evidence is lacking and further research is needed.

Cardiovascular biomarkers in chronic kidney disease: state of current research and clinical applicability

The high incidence of cardiovascular events in chronic kidney disease (CKD) warrants an accurate evaluation of risk aimed at reducing the burden of disease and its consequences. The use of biomarkers to identify patients at high risk has been in use in the general population for several decades and has received mixed reactions in the medical community. Some practitioners have become staunch supporters and users while others doubt the utility of biomarkers and rarely measure them. In CKD patients numerous markers similar to those used in the general population and others more specific to the uremic population have emerged; however their utility for routine clinical application remains to be fully elucidated. The reproducibility and standardization of the serum assays are serious limitations to the broad implementation of these tests. The lack of focused research and validation in randomized trials rather than ad hoc measurement of multiple serum markers in observational studies is also cause for concern related to the clinical applicability of these markers. We review the current literature on biomarkers that may have a relevant role in field of nephrology.

Cardiac troponin and C-reactive protein for predicting all-cause and cardiovascular mortality in patients with chronic kidney disease: a meta-analysis

Elevated serum levels of cardiac troponin and C-reactive protein are associated with all-cause and cardiovascular mortality in patients with end-stage renal disease. However, the relationship between these two biomarker levels and mortality in patients with chronic kidney disease remains unclear. We conducted a meta-analysis to quantify the association of cardiac troponin and C-reactive protein levels with all-cause and cardiovascular mortality in patients with chronic kidney disease. Relevant studies were identified by searching the MEDLINE database through November 2013. Studies were included in the meta-analysis if they reported the long-term all-cause or cardiovascular mortality of chronic kidney disease patients with abnormally elevated serum levels of cardiac troponin or C-reactive protein. Summary estimates of association were obtained using a random-effects model. Thirty-two studies met our inclusion criteria. From the pooled analysis, cardiac troponin and C-reactive protein were significantly associated with all-cause (HR 2.93, 95% CI 1.97-4.33 and HR 1.21, 95% CI 1.14-1.29, respectively) and cardiovascular (HR 3.27, 95% CI 1.67-6.41 and HR 1.19, 95% CI 1.10-1.28, respectively) mortality. In the subgroup analysis of cardiac troponin and C-reactive protein, significant heterogeneities were found among the subgroups of population for renal replacement therapy and for the proportion of smokers and the C-reactive protein analysis method. Elevated serum levels of cardiac troponin and C-reactive protein are significant associated with higher risks of all-cause and cardiovascular mortality in patients with chronic kidney disease. Further studies are warranted to explore the risk stratification in chronic kidney disease patients.

Practical aspects of volume control in chronic kidney disease using whole body bioimpedance

BACKGROUND

Fluid status is an independent predictor of mortality in dialysis patients. Current methods of fluid assessment have several limitations.

SUMMARY

An ideal method should be cheap, portable, easy to perform without extensive training, reproducible and determines patients' excess or deficit of total body water. Bioimpedance analysis (BIA) fulfils many of these criteria and can give additional information on fat and lean tissue composition. The accuracy and precision of BIA has been shown to be equivalent to the 'gold standard' direct estimation techniques.

KEY MESSAGES

Although there remains some concern about its validity in dialysis patients, fluid overload determined by BIA has been shown to predict mortality. BIA-guided fluid management appears superior to conventional fluid management in achieving clinically important outcomes such as reduction in blood pressure, left ventricular mass index, and arterial stiffness. Accurate setting of dry weight might also help preserve residual renal function by limiting episodes of dehydration. Nevertheless, as with all new technologies, there are issues that still need to be resolved. This will be achieved only with larger prospective interventional studies to explore its specific roles in dialysis cohorts.

Superior predictive value for NTproBNP compared with high sensitivity cTnT in dialysis patients: a pilot prospective observational study

BACKGROUND/AIMS

The clinical utility of the new biomarker, high sensitivity cardiac T troponin (hs-cTnT) is still unclear in dialysis patients. Furthermore, the prognostic value of combining N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) and hs-cTnT has not been explored so far. The objective of this pilot study was to determine the utility of hs-cTnT alone versus hs-cTnT in combination with NT-proBNP for predicting death in a stable hemodialysis cohort.

METHODS

A prospective observational pilot study including 98 chronic asymptomatic hemodialysis patients with a follow up period of 24 months was designed. The cut-off values for NT-proBNP and hs-cTnT were calculated using receiver operating characteristic (ROC) analysis, using mortality as an end-point. Based on the cut-off values, the cohort was divided into four groups. Group 1--NT-proBNP < 14275 pg/ml and hs-cTnT < 69.48 ng/l; group 2--NT-proBNP < 14275 pg/ml and hs-cTnT > 69.48 ng/l; group 3--NT-proBNP > 14275 pg/ml and hs-cTnT < 69.48 ng/l; group 4--NT-proBNP > 14275 pg/ml and hs-cTnT > 69.48 ng/l. Survival for each group was determined using the Kaplan-Meier method and Cox regression analysis.

RESULTS

During the follow-up period 16 patients died. According to the ROC curves analysis, the cut-off point for hs-cTnT and for NT-proBNP were 69.43 ng/l (AUC = 0.618; p = 0.04) and 14275 pg/ml (AUC = 0.722; p = 0.003), respectively. In univariate Cox analysis, both hs-cTnT (HR = 3.34; p = 0.016) and NT-proBNP (HR = 5.94; p = 0.01) were predictors of death. In the multivariable Cox proportional hazards model, only NT-pro-BNP levels above the cut-off value remained an independent predictor of all-cause mortality. The combined elevation of both biomarkers did not improve significantly the prognostic value compared with NT-proBNP alone (HR = 6.15 versus HR =4 .78; p = 0.338).

CONCLUSION

NT-pro-BNP is a strong predictor of overall mortality in asymptomatic hemodialysis patients. The addition of hs-cTnT did not improve the prognostic accuracy compared with NT proBNP alone.

Association of fluid overload with cardiovascular morbidity and all-cause mortality in stages 4 and 5 CKD

BACKGROUND AND OBJECTIVES

Fluid overload is a common characteristic associated with renal progression in CKD. Additionally, fluid overload is an independent predictor of all-cause or cardiovascular mortality in patients on dialysis, but its influence on patients not on dialysis is uncertain. The aim of the study was to assess the relationship between the severity of fluid status and clinical outcomes in an advanced CKD cohort.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In total, 478 predialysis patients with stages 4 and 5 CKD in the integrated CKD care program were enrolled from January of 2011 to December of 2011 and followed-up until August of 2013. The clinical outcomes included cardiovascular morbidity and all-cause mortality. The relative hydration status (overhydration/extracellular water) was used as the presentation of the severity of fluid status and measured using a body composition monitor. Overhydration/extracellular water >7% was defined as fluid overload.

RESULTS

Over a median follow-up period of 23.2 (12.6-26.4) months, 66 (13.8%) patients reached all-cause mortality or cardiovascular morbidity. The adjusted hazard ratio of the combined outcome of all-cause mortality or cardiovascular morbidity for every 1% higher overhydration/extracellular water was 1.08 (95% confidence interval, 1.04 to 1.12; P<0.001). The adjusted overhydration/extracellular water for the combined outcome of all-cause mortality or cardiovascular morbidity in participants with overhydration/extracellular water ≥7% compared with those with overhydration/extracellular water <7% was 1.93 (95% confidence interval, 1.01 to 3.69; P=0.04). In subgroup analysis, higher overhydration/extracellular water was consistently associated with increased risk for the combined outcome independent of diabetes, cardiovascular disease, and serum albumin. There was no significant interaction between all subgroups.

CONCLUSIONS

These findings suggest that fluid overload is an independent risk factor of the combined outcome of all-cause mortality or cardiovascular morbidity in patients with advanced CKD.

Fluid overload, pulse wave velocity, and ratio of brachial pre-ejection period to ejection time in diabetic and non-diabetic chronic kidney disease

Fluid overload is one of the characteristics in chronic kidney disease (CKD). Changes in extracellular fluid volume are associated with progression of diabetic nephropathy. Not only diabetes but also fluid overload is associated with cardiovascular risk factors The aim of the study was to assess the interaction between fluid overload, diabetes, and cardiovascular risk factors, including arterial stiffness and left ventricular function in 480 patients with stages 4–5 CKD. Fluid status was determined by bioimpedance spectroscopy method, Body Composition Monitor. Brachial-ankle pulse wave velocity (baPWV), as a good parameter of arterial stiffness, and brachial pre-ejection period (bPEP)/brachial ejection time (bET), correlated with impaired left ventricular function were measured by ankle-brachial index (ABI)-form device. Of all patients, 207 (43.9%) were diabetic and 240 (50%) had fluid overload. For non-diabetic CKD, fluid overload was associated with being female (β = –2.87, P = 0.003), heart disease (β = 2.69, P = 0.04), high baPWV (β = 0.27, P = 0.04), low hemoglobin (β = –1.10, P<0.001), and low serum albumin (β = –5.21, P<0.001) in multivariate analysis. For diabetic CKD, fluid overload was associated with diuretics use (β = 3.69, P = 0.003), high mean arterial pressure (β = 0.14, P = 0.01), low bPEP/ET (β = –0.19, P = 0.03), low hemoglobin (β = –1.55, P = 0.001), and low serum albumin (β = –9.46, P<0.001). In conclusion, baPWV is associated with fluid overload in non-diabetic CKD and bPEP/bET is associated with fluid overload in diabetic CKD. Early and accurate assessment of these associated cardiovascular risk factors may improve the effects of entire care in late CKD.

Evaluation of fluid status related parameters in hemodialysis and peritoneal dialysis patients: Clinical usefulness of bioimpedance analysis

BACKGROUND AND OBJECTIVE

Fluid overload is a common and serious problem that leads to severe complications in dialysis patients. We aimed to compare hydration status as measured with bioimpedance analysis (BIA) method in hemodialysis (HD) and peritoneal dialysis (PD) patients, as well as investigating the association between blood pressure, left ventricular mass index (LVMI) and hydration status.

MATERIALS AND METHODS

We examined 43 HD and 33 PD patients. Blood pressure was recorded. In each group, echocardiographic examinations were performed on all patients. Hydration status was assessed using multifrequency bioelectrical impedance analysis. Overhydration was defined as an overhydration (OH)/extracellular water (ECW) ratio of >0.15.

RESULTS

The OH/ECW ratio was significantly higher in PD patients compared to post-HD patients. Overhydration was statistically more frequent in PD than in post-HD patients (30.3% vs. 11.6%, P=0.043). Systolic blood pressure (SBP) in both post-HD and PD groups, and LVMI in the PD group were found to be significantly higher in overhydrated patients than non-overhydrated patients. In multiple linear regression analyses, increased OH/ECW ratio was independently associated with higher SBP and LVMI.

CONCLUSIONS

Fluid overload may be an even more prevalent and serious problem in PD patients. Overhydration is closely associated with increased blood pressure and LVMI. OH/ECW ratio, a derived parameter of fluid load measured by BIA, was a significant and independent determinant of SBP and LVMI.

Risk score to predict mortality in continuous ambulatory peritoneal dialysis patients

BACKGROUND

Patients with continuous ambulatory peritoneal dialysis (CAPD) have high all-cause mortality risk that varies extensively among different conditions. The objective of this study was to develop and validate risk models to predict the 2-year all-cause mortality risks of CAPD patients.

MATERIAL AND METHODS

A total of 1354 patients who received CAPD treatment > 3 months from a single dialysis centre were enrolled into the study from January 1, 2006 to December 31, 2011 and followed up until June 30, 2013. The dataset was randomly divided into the derivation dataset (2/3, n = 903) and the validation dataset (1/3, n = 451). Baseline information, including demographic characteristics, comorbid conditions and laboratory data, was recorded and included in the models. Risk models were developed using Cox proportional hazards regression. C-statistic, Akaike Information Criterion, Hosmer-Lemeshow χ(2) test and net reclassification improvement (NRI) were performed to evaluate model prediction and validation.

RESULTS

During the entire follow-up period, 175 (19·38%) and 85 (18·85%) patients died in the derivation and validation datasets respectively. A model that included age, diabetes mellitus, hypertension, cardiovascular disease, diastolic blood pressure, serum albumin, serum creatinine, phosphate, haemoglobin and fasting blood glucose demonstrated good discrimination in the derivation and validation datasets to predict 2-year all-cause mortality (C-statistic, 0·790 and 0·759, respectively). In the validation dataset, the above model performed good calibration (χ(2) = 2·08, P = 0·98) and NRI (7·37% compared with model 2, P = 0·05).

CONCLUSIONS

The risk model can accurately predict 2-year all-cause mortality in Chinese CAPD patients and external validation is needed in future.

Predialysis NTproBNP predicts magnitude of extracellular volume overload in haemodialysis patients

INTRODUCTION

Increased natriuretic peptides are associated with increased cardiovascular and all-cause mortality for haemodialysis (HD) patients. However, debate continues whether these biomarkers are increased by extracellular water (ECW) excess and can be used to aid clinical assessment of volume status and help determine target weight.

METHODS

We measured N terminal probrain natriuretic peptide (NT-proBNP) predialysis in 375 stable haemodialysis outpatients with corresponding pre and postdialysis multifrequency bioelectrical impedance assessments (MFBIA) of (ECW)/total body water (TBW).

RESULTS

Median age 64 (51-75), 63.9% male, 42.9% diabetic, 43.2% Caucasoid, 14.4% with a history of myocardial infarction, 8.4% coronary artery bypass surgery, dialysis vintage 28.2 (12.3-55.5) months. Median predialysis NT-proBNP 283 (123-989) pmol/l, and predialysis ECW/TBW ratio 0.397 ± 0.029. On multivariate analysis, predialysis log NT-proBNP was associated with predialysis systolic blood pressure (β 0.007, p = 0.000), weight (β -0.008, p = 0.001), valvular heart disease (β 0.342, p = 0.015, ECW/TBW (β 1.3, p = 0.019) and log CRP (β 0.145, p = 0.037). Dividing patients into NTproBNP quartiles, %ECW/TBW and relative ECW overhydration were significantly greater for the highest quartile vs. lowest (40.5 ± 4.1 vs. 39.0 ± 1.1, and 1.51 ± 1.24 vs. 0.61 ± 0.69 l, respectively, p < 0.001).

CONCLUSION

In this study, predialysis NTproBNP values were associated with direct assessments of the extracellular volume excess measured by MFBIA and systolic arterial blood pressure. This suggests that predialysis NTproBNP values can potentially be used to aid clinical assessment of volume status in dialysis patients to determine target weight.

Optimizing peritoneal dialysis prescription for volume control: the importance of varying dwell time and dwell volume

Not only adequate uremic toxin removal but also volume control is essential in peritoneal dialysis (PD) to improve patient outcome. Modification of dwell time impacts on both ultrafiltration (UF) and purification. A short dwell favors UF but preferentially removes small solutes such as urea. A long dwell favors uremic toxin removal but also peritoneal fluid reabsorption due to the time-dependent loss of the crystalloid osmotic gradient. In particular, the long daytime dwell in automated PD may result in significant water and sodium reabsorption, and in such cases icodextrin should be considered. Increasing dwell volume favors the removal of solutes such as sodium due to the increased volume of diffusion and the recruitment of peritoneal surface area. A very large fill volume with too high an intraperitoneal pressure (IPP) may, however, result in back-filtration and thus reduced UF and sodium clearance. Based on these principles and the individual transport and pressure kinetics obtained from peritoneal equilibration tests and IPP measurements, we suggest combining short dwells with a low fill volume to favor UF with long dwells and a large fill volume to favor solute removal. Results from a recent randomized cross-over trial and earlier observational data in children support this concept: the absolute UF and UF relative to the administered glucose increased and solute removal and blood pressure improved.

Inflammation and myocardial damage markers influence loss of residual renal function in peritoneal dialysis patients

BACKGROUND

Residual renal function (RRF) has been identified as the most important component in dialysis adequacy and has a strong effect on clinical outcomes. This justifies any effort in understanding the mechanism behind the preservation or decline in RRF. The aim of this study was to analyze the possible association of components of cardio-renal syndrome with the rate of decline in RRF.

METHODS

A retrospective cohort study was performed in a group of prevalent adult patients on continuous ambulatory peritoneal dialysis (CAPD). Patients were analyzed at baseline and after a 30-month follow-up. Evaluations included measurements of residual renal function, dialysis adequacy parameters, cardiovascular comorbidity, and measurements of biochemical markers of cardiovascular disease (CVD) and inflammation, as well as resting electrocardiography.

RESULTS

We included 129 patients in the study who were divided into groups according to loss of RRF, considering the cut-off point as 100 mL/day of 24 h urine volume. At baseline, there were no differences between groups: patients who lost RRF showed low values of 24 h urine volume, higher levels of systolic blood pressure, N-terminal pro-brain natriuretic peptide (NT-proBNP), C-reactive protein (CRP), IL-6, and low values of serum albumin. In the multivariate analysis, age, albumin, CRP, and NT-proBNP were significant risk factors for the loss of RRF.

CONCLUSIONS

Data indicate a close relationship between heart and kidney function where chronic kidney disease (CKD) affects and is an effect of, heart function, indicative of a bi-directional influence that leads to a vicious cycle, promoting deleterious effects on both systems.

Bioimpedance spectroscopy for the detection of fluid overload in Chinese peritoneal dialysis patients

BACKGROUND

Fluid overload probably contributes to the cardiovascular risk of peritoneal dialysis (PD) patients. We studied the relationship between over-hydration as determined by bioimpedance spectroscopy and dialysis adequacy, nutritional status, and arterial stiffness in Chinese PD patients.

METHODS

We studied 122 asymptomatic prevalent PD patients: bioimpedance spectroscopy, arterial pulse wave velocity, dialysis adequacy and nutritional status were determined.

RESULTS

Of the 122 patients, 88 (72.1%) had over-hydration of ≥ 1 L, while 25 (20.5%) were ≥ 5 L. Over-hydration significantly correlated with total body water (r = 0.474, p < 0.001) and extracellular water (r = 0.755, p < 0.001). Over-hydration was more severe in male and diabetic patients, and significantly correlated with Charlson's comorbidity score, blood pressure, body mass index, body weight, peritoneal transport characteristics, and carotid-femoral pulse wave velocity. Over-hydration significantly correlated with Kt/V (r = -0.287, p = 0.016), serum albumin level (r = -0.465, p < 0.001) and malnutrition inflammation score (r = 0.410, p = 0.006), but not residual renal function.

CONCLUSION

Over-hydration is common in asymptomatic Chinese PD patients. The degree of over-hydration is particularly pronounced in patients who are inadequately dialyzed, have multiple comorbid conditions and low serum albumin levels. Over-hydration is associated with high blood pressure and arterial stiffness, and may contribute to the excessive risk of cardiovascular disease in this group of patients.

Is fluid overload more important than diabetes in renal progression in late chronic kidney disease?

Fluid overload is one of the major presentations in patients with late stage chronic kidney disease (CKD). Diabetes is the leading cause of renal failure, and progression of diabetic nephropathy has been associated with changes in extracellular fluid volume. The aim of the study was to assess the association of fluid overload and diabetes in commencing dialysis and rapid renal function decline (the slope of estimated glomerular filtration rate (eGFR) less than -3 ml/min per 1.73 m(2)/y) in 472 patients with stages 4-5 CKD. Fluid status was determined by bioimpedance spectroscopy method, Body Composition Monitor. The study population was further classified into four groups according to the median of relative hydration status (△HS =fluid overload/extracellular water) and the presence or absence of diabetes. The median level of relative hydration status was 7%. Among all patients, 207(43.9 %) were diabetic. 71 (15.0%) subjects had commencing dialysis, and 187 (39.6%) subjects presented rapid renal function decline during a median 17.3-month follow-up. Patients with fluid overload had a significantly increased risk for commencing dialysis and renal function decline independent of the presence or absence of diabetes. No significantly increased risk for renal progression was found between diabetes and non-diabetes in late CKD without fluid overload. In conclusion, fluid overload has a higher predictive value of an elevated risk for renal progression than diabetes in late CKD.

Fluid overload in hemodialysis patients: a cross-sectional study to determine its association with cardiac biomarkers and nutritional status

Background

Chronic fluid overload is associated with higher mortality in dialysis patients; however, the link with cardiovascular morbidity has not formally been established and may be influenced by subclinical inflammation. We hypothesized that a relationship exists between fluid overload and [i] cardiovascular laboratory parameter as well as between fluid overload and [ii] inflammatory laboratory parameters. In addition, we aimed to confirm whether volume status correlates with nutritional status.

Methods

We recorded baseline characteristics of 244 hemodialysis patients at three hemodialysis facilities in Vienna (Austria) and determined associations with volume measurements using the body composition monitor (Fresenius/Germany). In one facility comprising 126 patients, we further analyzed cardiovascular, inflammatory and nutritional parameters.

Results

We detected predialysis fluid overload (FO) in 39% of all patients (n = 95) with FO defined as ≥15% of extracellular water (ECW). In this subgroup, the absolute FO was 4.4 +/-1.5 L or 22.9 ± 4.8% of ECW. A sub-analysis of patients from one center showed that FO was negatively associated with body mass index (r = -0.371; p = <0.001), while serum albumin was significantly lower in fluid overloaded patients (p = 0.001). FO was positively associated with D-Dimer (r = 0.316; p = 0.001), troponin T (r = 0.325; p < 0.001), and N-terminal pro-B-type natriuretic peptide (r = 0.436; p < 0.001), but not with investigated inflammatory parameters.

Conclusions

Fluid overload in HD patients was found to be lower in patients with high body mass index, indicating that dry weight was inadequately prescribed and/or difficult to achieve in overweight patients. The association with parameters of cardiovascular compromise and/or damage suggests that fluid overload is a biomarker for cardiovascular risk. Future studies should determine if this applies to patients prior to end-stage renal disease.

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.

Association of fluid overload with kidney disease progression in advanced CKD: a prospective cohort study

BACKGROUND

Fluid overload is a common phenomenon in patients in a late stage of chronic kidney disease (CKD). However, little is known about whether fluid overload is related to kidney disease progression in patients with CKD. Accordingly, the aim of the study was to assess the association of the severity of fluid status and kidney disease progression in an advanced CKD cohort.

STUDY DESIGN

Prospective observational cohort study.

SETTING & PARTICIPANTS

This cohort study enrolled 472 non-dialysis-dependent patients with CKD stages 4-5 who were in an integrated CKD care program from January 2011 to December 2011 and followed up until December 2012 or initiation of renal replacement therapy (RRT).

PREDICTORS

Tertile of fluid overload, with cutoff values at 0.6 and 1.6 L.

OUTCOMES

RRT, rapid estimated glomerular filtration rate (eGFR) decline (faster than 3 mL/min/1.73 m(2) per year), and change in eGFR.

MEASUREMENTS

The severity of fluid overload was measured by a bioimpedance spectroscopy method. eGFR was computed using the 4-variable MDRD (Modification of Diet in Renal Disease) Study equation.

RESULTS

During a median 17.3-month follow-up, 71 (15.0%) patients initiated RRT and 187 (39.6%) experienced rapid eGFR decline. The severity of fluid overload was associated with increased risk of RRT (tertile 3 vs tertile 1: adjusted HR, 3.16 [95% CI, 1.33-7.50]). Fluid overload value was associated with increased risk of rapid eGFR decline (tertile 3 vs tertile 1: adjusted OR, 4.68 [95% CI, 2.30-9.52]). Furthermore, the linear mixed-effects model showed that the reduction in eGFR over time was faster in tertile 3 than in tertile 1 (P=0.02).

LIMITATIONS

The effect of fluid volume variation over time must be considered.

CONCLUSIONS

Fluid overload is an independent risk factor associated with initiation of RRT and rapid eGFR decline in patients with advanced CKD.

Cohort profile: Canadian study of prediction of death, dialysis and interim cardiovascular events (CanPREDDICT)

Background

The Canadian Study of Prediction of Death, Dialysis and Interim Cardiovascular Events (CanPREDDICT) is a large, prospective, pan-Canadian, cohort study designed to improve our understanding of determinants of renal and cardiovascular (CV) disease progression in patients with chronic kidney disease (CKD). The primary objective is to clarify the associations between traditional and newer biomarkers in the prediction of specific renal and CV events, and of death in patients with CKD managed by nephrologists. This information could then be used to better understand biological variation in outcomes, to develop clinical prediction models and to inform enrolment into interventional studies which may lead to novel treatments.

Methods/Designs

Commenced in 2008, 2546 patients have been enrolled with eGFR between 15 and 45 ml/min 1.73m2 from a representative sample in 25 rural, urban, academic and non academic centres across Canada. Patients are to be followed for an initial 3 years at 6 monthly intervals, and subsequently annually. Traditional biomarkers include eGFR, urine albumin creatinine ratio (uACR), hemoglobin (Hgb), phosphate and albumin. Newer biomarkers of interest were selected on the basis of biological relevance to important processes, commercial availability and assay reproducibility. They include asymmetric dimethylarginine (ADMA), N-terminal pro-brain natriuretic peptide (NT-pro-BNP), troponin I, cystatin C, high sensitivity C-reactive protein (hsCRP), interleukin-6 (IL6) and transforming growth factor beta 1 (TGFβ1). Blood and urine samples are collected at baseline, and every 6 monthly, and stored at −80°C. Outcomes of interest include renal replacement therapy, CV events and death, the latter two of which are adjudicated by an independent panel.

Discussion

The baseline distribution of newer biomarkers does not appear to track to markers of kidney function and therefore may offer some discriminatory value in predicting future outcomes. The granularity of the data presented at baseline may foster additional questions.

The value of the cohort as a unique resource to understand outcomes of patients under the care of nephrologists in a single payer healthcare system cannot be overstated. Systematic collection of demographic, laboratory and event data should lead to new insights.

The mean age of the cohort was 68 years, 90% were Caucasian, 62% were male, and 48% had diabetes. Forty percent of the cohort had eGFR between 30–45 mL/min/1.73m², 22% had eGFR values below 20 mL/min/1.73m²; 61% had uACR < 30. Serum albumin, hemoglobin, calcium and 25-hydroxyvitamin D (25(OH)D) levels were progressively lower in the lower eGFR strata, while parathyroid hormone (PTH) levels increased. Cystatin C, ADMA, NT-proBNP, hsCRP, troponin I and IL-6 were significantly higher in the lower GFR strata, whereas 25(OH)D and TGFβ1 values were lower at lower GFR. These distributions of each of the newer biomarkers by eGFR and uACR categories were variable.

Subcutaneous interstitial pressure and volume characteristics in renal impairment associated with edema

The kidneys and the interstitial compartment play a vital role in body fluid regulation. The latter may be significantly altered in renal dysfunction, but experimental studies are lacking. To help define this we measured the subcutaneous interstitial pressure, bioimpedance volumes, and edema characteristics in 10 healthy subjects and 21 patients with obvious edema and chronic kidney disease (CKD). Interstitial edema was quantified by the time taken for a medial malleolar thumb pit to refill and termed the edema refill time. Interstitial pressure was significantly raised in CKD compared to healthy subjects. Total body water (TBW), extracellular fluid volume (ECFV), interstitial fluid volume, the ratio of the ECFV to the TBW, and segmental extracellular fluid volume were raised in CKD. The ratio of the ECFV to the TBW and the interstitial fluid volume were the best predictors of interstitial pressure. Significantly higher interstitial pressures were noted in edema of 2 weeks or less duration. A significant nonlinear relationship defined interstitial pressure and interstitial fluid volume. Edema refill time was significantly inversely related to interstitial pressure, interstitial compartment volumes, and edema vintage. Elevated interstitial pressure in CKD with obvious edema is a combined function of accumulated interstitial compartment fluid volumes, edema vintage, and tissue mechanical properties. The edema refill time may represent an important parameter in the clinical assessment of edema, providing additional information about interstitial pathophysiology in patients with CKD and fluid retention.

Peritoneal dialysis--current status and future challenges

Peritoneal dialysis is now a well established, mature treatment modality for advanced chronic kidney disease. The medium term (at least 5 year) survival of patients on peritoneal dialysis is currently equivalent to that of those on haemodialysis, and is particularly good in patients who are new to renal replacement therapy and have less comorbidity. Nevertheless the modality needs to keep pace with the constantly evolving challenges associated with the provision and delivery of health care. These challenges, which are gradually converging at a global level, include ageing of the population, multimorbidity of patients, containment of cost, increasing self care and environmental issues. In this context, peritoneal dialysis faces particular challenges that include multiple barriers to the therapy and unsatisfactory and poorly defined technique survival as well as limitations relating to intrinsic aspects of the therapy, such as peritoneal membrane longevity and hypoalbuminaemia. To move the therapy forward and favourably influence health-care policy, the peritoneal dialysis community needs to integrate their research effort more effectively by undertaking clinically meaningful studies-with a strong focus on technique survival--that are supported by multidisciplinary expertise in patient-centred outcomes, study design and analysis.

Biomarkers in native and transplant kidneys: opportunities to improve prediction of outcomes in chronic kidney disease

PURPOSE OF REVIEW

Predicting the outcomes of patients with chronic kidney disease (CKD) is important from both patient and healthcare system perspectives. This review examines the current state of conventional and nonconventional biomarkers as noninvasive tools to improve risk-stratification and outcome prediction in CKD.

RECENT FINDINGS

Conventional biomarkers (serum creatinine, urine albumin, and clinical variables such as sex, age, and diabetes) have been the cornerstone of most prediction models for CKD progression to end-stage renal disease (ESRD), and adverse cardiovascular outcomes including death. With better understanding of the pathophysiology of CKD and the evolution of molecular diagnostics, numerous novel or nonconventional markers have emerged. They have been examined individually and in combination to predict specific outcomes. We highlight these markers and studies, conducted primarily in patients with native kidneys. In those with transplant kidneys, markers of both acute and chronic kidney dysfunction have been examined, although to a lesser extent. Similarities and differences in knowledge derived from these two populations are highlighted.

SUMMARY

Improving prediction of outcomes in CKD patients with either native or transplant kidneys remains an important goal. Increasingly sophisticated biomarkers may potentially identify targets for clinical research, improve the nature and timing of therapeutic interventions, and guide resource allocation.

The relationship of NT-proBNP and dialysis parameters with outcome of incident haemodialysis patients: results from the membrane permeability outcome study

BACKGROUND/AIMS

The association of raised levels of natriuretic peptides with elevated risk of mortality was investigated in the present analysis of the Membrane Permeability Outcome study.

METHODS

N-terminal probrain type natriuretic peptide (NT-proBNP) was measured in 618 incident haemodialysis patients, randomised to either high-flux or low-flux. Characteristics of patients with NT-proBNP levels below or above the median were descriptively analysed and survival analysis was performed.

RESULTS

Median NT-proBNP value was 2,124 pg/ml, with 1,854 pg/ml in the high-flux and 2,919 pg/ml in the low-flux group. Survival probability was lowest in patients with both a history of cardiovascular disease and NT-proBNP values above the median (p < 0.001). A multivariate Cox proportional hazard model showed interaction between presence of cardiovascular diseases and NT-proBNP levels above the median.

CONCLUSIONS

NT-proBNP is an independent predictor of mortality also in incident haemodialysis patients. Lower concentrations associated with high-flux dialysis suggest a possible biological link to improved survival in this group.

Dynamic cardiac dyssynchrony is strongly associated with 2-year dialysis adequacy in continuous ambulatory peritoneal dialysis patients

BACKGROUND

Left ventricular (LV) dyssynchrony is associated with increased risk of all-cause mortality in patients with end-stage renal disease. Our aim was to determine the associations of LV dynamic dyssynchrony with peritoneal solute clearance in continuous ambulatory peritoneal dialysis (CAPD) patients. Our primary objective was to determine the association between dynamic LV dyssynchrony and CAPD clearance at 2 years. Secondary objectives were to identify the factors influencing dynamic dyssynchrony, and to examine the association between dialysis adequacy and echocardiography-assessed LV outcomes.

METHODS

Fifty CAPD patients and 13 healthy volunteers underwent three-dimensional (3D) dobutamine stress echocardiography (DSE). The main endpoint was systolic dyssynchrony index (SDI). Secondary endpoints, including NT-proBNP, troponin I, Kt/V, and biochemical parameters, were measured before stress echocardiography, and Kt/V was measured again 2 years later. All values are expressed as medians and interquartile ranges (IQR).

RESULTS

NT-proBNP (3872 [808-11779] vs. 4.99 [4.99-36.83] pg/mL, P < 0.001), and log NT-proBNP (3.587 [2.896-4.071] vs. 0.698 [0.698-1.540], P < 0.001) levels were significantly higher in the CAPD group than in the control group. Real-time 3D DSE showed that the systolic dyssynchrony index was significantly different between the two groups at the peak dobutamine stage (1.11% [0.76-1.64%] vs. 0.66% [0.50-1.02%], P = 0.004), but not at resting (1.30% [0.89-1.74%] vs. 1.22 % [0.72-1.68%], P = 0.358).The subgroup of patients in the CAPD group with greater improvements in dialysis adequacy had lower baseline dynamic SDI and more favorable echocardiographic findings at 2 years. Dialysis adequacy decreased significantly at 2 year in patients with higher, but not in those with lower dynamic SDI at baseline. In multivariate linear regression analysis, log NT-proBNP and SDI at the peak dobutamine dose were significantly associated with Kt/V and weekly creatinine clearance at 2 years, while log NT-proBNP was significant associated with SDI at the peak dobutamine stage. Female CAPD patients group had more pronounced dynamic LV dyssynchrony compared with male patients.

CONCLUSIONS

Dynamic systolic dyssynchrony was strongly associated with future dialysis adequacy in CAPD patients. Log NT-proBNP was the important predictor of dynamic dyssynchrony. Our study confirmed the concept that cardiac dysfunction has an impact on dialysis adequacy.

Is there a role for N-terminal probrain-type natriuretic peptide in determining volume status in haemodialysis patients?

BACKGROUND/AIMS

Natriuretic peptides have been reported to be a valuable biomarker for predicting cardiac events and mortality for haemodialysis patients. However, there has been a debate as to whether these biomarkers can be used to assess volume overload and help determine dry weight.

METHODS

We measured the N-terminal probrain natriuretic peptide (NTproBNP) in 366 stable haemodialysis outpatients with a corresponding pre- and post-dialysis multifrequency bioimpedance assessment of extracellular water (ECW)/total body water (TBW).

RESULTS

Median age was 61 years (46-73); 58.5% were male, 28.5% diabetic, and 37.7% Caucasoid; 71.1% had a history of hypertension, 8.4% of myocardial infarction, and 9.3% of coronary artery bypass surgery; dialysis vintage was 54 months (22-85.5), and urea reduction ratio was 73.4 ± 7.6%. Median post-dialysis NTproBNP was 179 pmol/l (68-535), pre-dialysis ECW/TBW was 0.393 ± 0.014, and post-dialysis ECW/TBW was 0.385 ± 0.015. On multivariate analysis log NTproBNP was associated with post-dialysis ECW/TBW (β 9.09, 95% CI 3.22-14.95, p = 0.003), mean arterial pressure (β 0.0087, 95% CI -0.0045 to -0.013, p = 0.000), and ultrafiltration rate (ml/kg · h; β 0.038, 95% CI 0.01-0.06, p = 0.001).

CONCLUSION

In this study postdialysis NTproBNP values were correlated with direct assessments of volume status in haemodialysis patients, i.e. by ECW/TBW, or indirect measures of volume overload, i.e. ultrafiltration rate and post-dialysis mean arterial blood pressure. This suggests that serial NTproBNP values may aid clinical assessments of volume status in dialysis patients.

Sodium removal and peritoneal dialysis modalities: no differences with optimal prescription of icodextrin

Continuous ambulatory peritoneal dialysis (CAPD) has been considered as a more efficient modality for sodium removal than automated peritoneal dialysis (APD), due to the longer dwell times and the sodium sieving phenomenon. However, because studies regarding sodium removal in peritoneal dialysis (PD) report rather controversial results and carry various methodological flaws, it remains uncertain whether they offer enough significant information regarding PD prescription and therapy. The aim of the present observational cross-sectional study was to evaluate the impact of the optimal prescription of CAPD and APD, regarding solute clearances and daily ultrafiltrate, on daily sodium removal. Forty-six (46) patients aged 52.3 ± 14 years were studied. Twenty-six (26) patients were subjected to CAPD, and 20 patients were subjected to APD. Ten (10) patients per group were prescribed icodextrin for the long dwell to achieve optimal adequacy and ultrafiltration (UF) targets. CAPD patients removed a higher, albeit not statistically significant, daily amount of sodium (131.7 ± 98.2 mmol) compared with APD patients (79.4 ± 129.2 mmol). Their Kt/V urea was lower (1.48 ± 0.3 vs. 2.17 ± 0.33, P < 0.05), and there were no differences on daily UF (1119 ± 533 vs. 1005 ± 517 mL). In both groups, icodextrin use for the long dwell resulted in equal sodium removal with that of patients not prescribed icodextrin. Our results, derived from an unselected PD population, indicate that although classic CAPD may be more efficient for sodium removal than APD, the use of icodextrin as an adjuvant for higher daily UF not only increases solute clearance but also removes more sodium for both modalities. In addition, calculations of sodium removal in PD do not seem to benefit the everyday clinical practice, provided that PD patients can achieve the adequacy targets and present optimal daily UF without signs of volume overload.

Prevalence and risk factors of fluid overload in Southern Chinese continuous ambulatory peritoneal dialysis patients

Background

Fluid overload is frequently present in CAPD patients and one of important predictors of mortality. The aim of this study is to investigate the prevalence and associated risk factors in a cohort study of Southern Chinese CAPD patients.

Methods

The patients (receiving CAPD 3 months and more) in our center were investigated from January 1, 2008 to December 31, 2009. Multi-frequency bioelectrical impedance analysis was used to assess the patient’s body composition and fluid status.

Results

A total of 307 CAPD patients (43% male, mean age 47.8±15.3 years) were enrolled, with a median duration of PD 14.6 (5.9–30.9) months. Fluid overload (defined by Extracellular water/Total body water (ECW/TBW)≥0.40) was present in 205 (66.8%) patients. Univariate analysis indicated that ECW/TBW were inversely associated with body mass index (r = −0.11, P = 0.047), subjective global assessment score (r = −0.11, P = 0.004), body fat mass (r = −0.15, P = 0.05), serum albumin (r = −0.32, P<0.001), creatinine (r = −0.14, P = 0.02), potassium (r = −0.15, P = 0.02), and residual urine output (r = −0.14, P = 0.01), positively associated with age (r = 0.27, P<0.001), Chalrlson Comorbidity Index score (r = 0.29, P<0.001), and systolic blood pressure (r = 0.22, P<0.001). Multivariate linear regression showed that lower serum albumin (β = −0.223, P<0.001), lower body fat mass (β = −0.166, P = 0.033), old age (β = 0.268, P<0.001), higher systolic blood pressure (β = 0.16, P = 0.006), less residual urine output (β = −0.116, P = 0.042), and lower serum potassium (β = −0.126, P = 0.03) were independently associated with higher ECW/TBW. After 1 year of follow-up, the cardiac event rate was significantly higher in the patients with fluid overload (17.1% vs 6.9%, P = 0.023) than that of the normal hydrated patients.

Conclusions

The prevalence of fluid overload was high in CAPD patients. Fluid overload in CAPD patients were independently associated with protein-energy wasting, old age, and decreased residual urine output. Furthermore, CAPD patients with fluid overload had higher cardiac event rate than that of normal hydrated patents.

Assessment of fluid status in CAPD patients using the body composition monitor

AIMS AND OBJECTIVES

To assess the degree of overhydration in our peritoneal dialysis patients and to examine the factors contributing to overhydration.

BACKGROUND

Volume control is critical for the success of peritoneal dialysis, but dry weight has been difficult to ascertain accurately. Chronic fluid overload and hypertension are among the leading causes of mortality in dialysis patients.

DESIGN

A cross-sectional observational study.

METHODS

The body composition monitor (Fresenius Medical Care, Bad Homburg, Germany) is a bioimpedance spectroscopy device that has been validated for the assessment of overhydration. We used this body composition monitor device on all patients on continuous ambulatory peritoneal dialysis at our institution who met the inclusion criteria to assess their degree of overhydration.

RESULTS

Thirty four (17 men, 17 women; mean age 44·5 ± 14·2 years) of a 45 continuous ambulatory peritoneal dialysis patients were enrolled. The mean overhydration was 2·4 ± 2·4 l. Fifty per cent of the patients were ≥2 l overhydrated. Overhydration correlated with male gender, low serum albumin, increasing number of antihypertensive agents and duration of dialysis. There was no difference in overhydration between diabetic and non-diabetic patients. Men were more overhydrated than women, had lower Kt/V and were older. Although, there was no difference in blood pressure between the genders, men had a trend towards a higher usage of antihypertensive agents.

CONCLUSION

Our study demonstrates that overhydration is common in peritoneal dialysis patients. Blood pressure should ideally be controlled with adherence to dry weight and low salt intake rather than adding antihypertensive agents even in the absence of clinical oedema.

RELEVANCE TO CLINICAL PRACTICE

Body composition monitor is a simple, reliable and inexpensive tool that can be routinely used in the outpatient clinic setting or home visit to adjust the dry weight and avoid chronic fluid overload in between nephrologists review.

Changes in N-terminal pro-brain natriuretic peptide correlate with fluid volume changes assessed by bioimpedance in peritoneal dialysis patients

BACKGROUND/AIMS

Both brain natriuretic peptide (BNP) and volume overload are reported to be powerful predictors of survival for peritoneal dialysis patients. The usefulness of single BNP determinations in helping determine volume status in peritoneal dialysis patients remains controversial, so we reviewed serial BNP and multifrequency bioimpedance measurements to determine whether changes in BNP reflected changes in volume status.

METHODS

Prospective measurements of fluid volume by multifrequency bioimpedance and serum N-terminal pro-BNP (NTproBNP) were conducted in stable adult peritoneal dialysis outpatients attending for routine assessments of peritoneal dialysis adequacy and transport status.

RESULTS

A total of 189 serial measurements were made in 92 patients, and NTproBNP increased from a median of 162.5 pmol/l (interquartile range 82-385.4) to 195 pmol/l (interquartile range 101.9-348.6; p < 0.05). Changes in NTproBNP correlated with changes in extracellular water (ECW), total body water (TBW) and ECW/TBW (r = 0.38, 0.31 and 0.45, respectively; all p < 0.0001). Patients were divided into quartiles depending upon NTproBNP changes; those with the greatest fall in NTproBNP had significant falls in ECW (p < 0.001), TBW (p = 0.001) and ECW/TBW (p < 0.001) compared to the quartile with the greatest increase in NTproBNP, who also had an increase in systolic blood pressure from 133.5 ± 22.7 to 142.7 ± 28.8 mm Hg (p = 0.0078), whereas it fell in the quartile with the greatest fall in NTproBNP (143.8 ± 24.6 vs. 136.5 ± 18.7 mm Hg).

CONCLUSIONS

Serial measurements of NTproBNP correlated with changes in volume assessments made by multifrequency bioimpedance in peritoneal dialysis outpatients. As multifrequency bioimpedance measures total ECW, rather than effective plasma volume, serial NTproBNP determinations may prove an adjunct to the clinical assessment of volume status in peritoneal dialysis patients.

Peritoneal dialysis as compared with hemodialysis is associated with higher overhydration but non-inferior blood pressure control and heart function

BACKGROUND/AIMS

Fluid overload is an important factor causing cardiovascular complications in dialysis patients. We compared fluid status, blood pressure (BP) and heart function between peritoneal dialysis (PD) patients and hemodialysis (HD) patients.

METHODS

We recruited 94 PD and 75 HD patients in our hospital. Fluid status was assessed by bioimpedance spectroscopy. Home BP was recorded. Use of antihypertensives was retrieved by chart review. In each group, 39 patients received echocardiographic examinations.

RESULTS

PD patients' fluid status was similar to that of predialysis HD patients. PD patients had lower systolic BP. E/E' and left ventricular mass index (LVMI) showed no significant intergroup difference. In multiple linear regression analyses, overhydration (OH)/extracellular water ratio >0.15 was associated with higher systolic BP, E/E' and LVMI.

CONCLUSIONS

While PD was associated with higher OH but non-inferior BP control and heart function, OH was indeed related to poor BP control, diastolic dysfunction and left ventricular hypertrophy.

Volume status in patients on peritoneal dialysis: the role of apelin and bio-impedance spectroscopy

One of the main factors determining the survival of peritoneal dialysis (PD) patients is volume status. We aimed to investigate hydration status of PD patients by bio-impedance spectroscopy (BIS) and echocardiography and to study the relation of them with apelin, which has effects related with volume status like vasodilation, positive inotropism, and inhibition of ADH release and RAS antagonism. Chronic PD patients without active cardiac disease or clinically prominent hypervolemia were included. Besides the demographic, clinical, and laboratory data, BIS and echocardiographic findings together with apelin levels were recorded. The study included 21 patients. Of them, eight patients were euvolemic, one patient was hypovolemic, and others have some degree of overhydration (1.1-6.8 L) with BIS, although all were euvolemic clinically. Mean apelin level was 1.49 ± 0.49 ng/mL. Apelin level was positively correlated with ejection fraction and negatively with total body water (TBW), intracellular and extracellular water, lean tissue mass, and left atrium diameter. On linear regression model, TBW was the major determinant of apelin. Although apelin is expected to increase in hypervolemic patients, the negative correlation with body water in this study may be related with yet unknown role of apelin in dialyzed patients. They may have important roles in volume status in future.

Elderly dialysis patients: analysis of factors affecting long-term survival in 4-year prospective observation

Purpose

To assess factors influencing the long-term survival of elderly dialysis patients.

Methods

The study group consisted of 51 prevalent dialysis patients aged over 70 years (32 F and 19 M, all caucasians), who had been on a chronic hemodialysis (27) or peritoneal dialysis program (24) for at least 2 months; median age was 77 years, median time on dialysis before inclusion was 16 months, and median residual diuresis was 600 ml. The patients were prospectively followed up to 4 years, and an analysis of factors affecting survival was performed.

Results

Thirteen patients from the initial cohort of 51 (25.5 %) survived the whole 48-month observation period: 10 HD patients (37 %) and 3 PD patients (12.5 %). Annual mortality rate was 28.2 %: 37.4 % on PD vs. 20.9 % on HD. The dialysis modality had a significant impact on patients’ survival (p = 0.049; Cox F-test). The independent mortality risk factors in the Cox proportional hazard regression model were higher plasma pro-atrial natriuretic peptide (pro-ANP) (p = 0.006), lower residual diuresis (p = 0.048), and lower systolic blood pressure (BP) value (p = 0.039).

Conclusions

Paramount for the survival of the elderly on dialysis is adequate extracellular volume control. Residual renal function is a protective factor for the survival of elderly HD patients. This observation is novel, not previously reported in an elderly dialysis population.

Serum alkaline phosphatase levels and left ventricular diastolic dysfunction in patients with advanced chronic kidney disease

BACKGROUND

High levels of alkaline phosphatase (ALP) have been associated with increased mortality in patients with advanced chronic kidney disease (CKD). We hypothesize that elevated ALP could be partly explained by subclinical liver congestion related to left ventricular diastolic dysfunction.

METHODS

Doppler echocardiography was performed in 68 patients with advanced CKD followed up for a median of 2.1 years. Time-averaged levels of ALP and γ-glutamyl transferase (GGT) were compared between patients with and without diastolic dysfunction. We also evaluated the effect of intensifying diuretic treatment on ALP levels in a small group of 16 patients with high ALP and signs of volume overload.

RESULTS

ALP correlated significantly (p < 0.001) with GGT but not with parathyroid hormone (p = 0.09). Patients with diastolic dysfunction showed higher ALP (p = 0.01), higher GGT (p = 0.03) and lower albumin (p = 0.04). The highest values of ALP were observed in patients with diastolic dysfunction plus pulmonary hypertension (p = 0.01). Intensifying diuretic therapy in a subgroup of patients with signs of fluid overload induced a significant reduction in body weight, GGT (p < 0.001) and ALP levels (p < 0.001).

CONCLUSIONS

Elevated ALP in patients with advanced CKD could be partly explained by subclinical liver congestion related to left ventricular diastolic dysfunction, hypervolemia or both. The worse prognosis of these patients could be explained by their myocardial damage.

Volume excess in chronic haemodialysis patients--effects of treatment frequency and treatment spacing

BACKGROUND

The main objective of this study was to theoretically quantify the fluctuations of fluid volume excess for different modes of intermittent ultrafiltration schedules and to compare the prediction for the typical and asymmetric thrice-weekly schedule to clinical, physiological and biophysical markers of volume expansion in a group of stable haemodialysis patients.

METHODS

Overall volume excess (V(OVE)) was described as the sum of a time-independent (V(0)) and a time-dependent component (V). An exact relationship was developed to relate V to variable treatment frequency, treatment spacing and net volume accumulation rate. In a single-centre haemodialysis population, body mass profiling was combined with volume state evaluation by bioimpedance analysis, N-terminal pro-B-type natriuretic peptide (NT-pro BNP) levels, clinical signs, a volume questionnaire and blood pressure levels.

RESULTS

In 23 patients following the typical thrice-weekly schedule, the time-averaged volume excess (V) during the whole week (1.1 ± 0.5 L) was significantly larger than that during the midweek interval (0.9 ± 0.4 L) (P < 0.002) by a factor comparable to that of 1.21 obtained from the theoretical analysis. V(OVE) was 1.3 ± 1.7 L and significantly related to pre- (P < 0.001) and post-dialysis levels of NT-pro BNP (P < 0.001).

CONCLUSION

Asymmetric treatment spacing such as with the typical thrice-weekly treatment schedule leads to a significant increase in time-averaged volume excess. The theoretical analysis allows for comparison of time-averaged volume excess in treatments varying with regard to treatment frequency and regularity and could be helpful to prescribe post-treatment volume (target weight) for such variable treatment modes.

Peritoneal dialysis in diabetics: there is room for more

End stage renal disease diabetic patients suffer from worse clinical outcomes under dialysis-independently of modality. Peritoneal dialysis offers them the advantages of home therapy while sparing their frail vascular capital and preserving residual renal function. Other benefits and potential risks deserve discussion. Predialysis intervention with early nephrology referral, patient education, and multidisciplinary support are recommended. Skilled and updated peritoneal dialysis protocols must be prescribed to assure better survival. Optimized volume control, glucose-sparing peritoneal dialysis regimens, and elective use of icodextrin are key therapy strategies. Nutritional evaluation and support, preferential use of low-glucose degradation products solutions, and prescription of renin-angiotensin-aldosterone system acting drugs should also be part of the panel to improve diabetic care under peritoneal dialysis.