Associations between central pulse pressure, microvascular endothelial function, and fluid overload in peritoneal dialysis patients

BACKGROUND

Microcirculatory endothelial dysfunction is a complex phenomenon that contributes to the development of cardiovascular disease. However, the relationship between microcirculatory endothelial dysfunction and macrovascular disease remains incompletely understood. Fluid overload is a risk factor for cardiovascular mortality in patients undergoing peritoneal dialysis. Therefore, we investigated the effects of chronic fluid overload on both the microcirculation and macrocirculation in these patients.

METHODS

Thirty patients undergoing peritoneal dialysis were included in this cross-sectional study. We measured their central blood pressure and pulse wave velocity, assessed their microvascular endothelial function using drug-induced iontophoresis with laser Doppler flowmetry, and determined the amount of fluid overload using bioimpedance. We conducted a Spearman correlation analysis, univariate analysis, and stepwise multivariate regression models to determine the associations among the hemodynamic parameters.

RESULTS

Acetylcholine-induced iontophoresis with laser Doppler flowmetry showed a correlation with both brachial and central pulse pressure (PP), but not with pulse wave velocity. Fluid overload was associated with both central and brachial PP and remained an independent predictor of central PP even after adjusting for multiple factors. However, fluid overload was not associated with microcirculatory endothelial function.

CONCLUSION

In peritoneal dialysis patients, we observed a significant association between central PP and microvascular endothelial function, indicating a connection between macrocirculation and microcirculation. However, conclusive evidence regarding fluid overload as a mediator between these circulatory systems is lacking. Further research is needed to investigate this relationship.

The role of segmental bioelectrical impedance technique in the assessment of intraperitoneal ultrafiltration volume with peritoneal dialysis patients

OBJECTIVE

To investigate the role of segmental bioelectrical impedance technique (SBIA) in the assessment of intraperitoneal ultrafiltration volume with peritoneal dialysis patients.

METHOD

We selected the patients at the Department of Nephrology of the First Affiliated Hospital of Zhengzhou University and measured the segmental bioelectrical impedance by a German Fresenius body composition analyzer (the Fresenius whole body composition measurement (BCM) machine was used as a segmental machine in this study). An alternating current (5 kHz, 0.05-0.7 mA) was continuously released during the measurement. The released current penetrated the peritoneal cavity on both sides of the body, from which the segmental resistance at a frequency of 5 kHz was obtained from the multifrequency data (R5/Ω). Baseline BIA measurements were initiated after the patient entered the supine position for 5-10 min, then dialysate was instilled into the peritoneal cavity. BIA measurements were performed at 10-min intervals during the retention of dialysate in the abdomen and finally ended when dialysate drainage was complete. Real-time intraperitoneal volume estimated by SBIA (IPVSBIA)and ultrafiltration volume estimated by SBIA(UFVSBIA) was calculated. At the same time, the actual ultrafiltration volume at the end of peritoneal dialysis was weighed and measured (UFVMEA).

RESULTS

A total of 30 patients were included in the study, 9 patients withdrew from the study due to subjective factors during the measurement process, and 21 patients completed the study. The correlation coefficient R2 of UFVSBIA and UFVMEA was 0.21 (p < 0.05). Bland-Altman analysis showed that the bias of UFVSBIA to the actual UFVMEA was 0.12 L, and the 95% agreement limit was between -0.5 L and 0.74 L, which confirmed that UFVSBIA measured by electrical impedance method and UFVMEA measured by weighing method were in good agreement. The time required to reach the maximum ultrafiltration volume (UFVSBIA) was 108 ± 68 min, and the mean value of the maximum ultrafiltration volume (Max UFVSBIA) was 1.16 ± 0.60 L.

CONCLUSION

The segmental bioelectrical impedance technique can be used to assess the intraperitoneal ultrafiltration volume of peritoneal dialysis patients in real-time and effectively. This method may guide the dialysis fluid retention time and the maximum ultrafiltration volume in PD patients.

Association between phase angle and coronary artery calcium score in patients on peritoneal dialysis

Introduction

The phase angle (PhA) has been used as a nutritional marker and predictor of mortality in patients on peritoneal dialysis (PD). The coronary artery calcium (CAC) score has shown to predict the incidence of acute myocardial infarction and death from cardiovascular disease in these patients. However, the association between PhA and CAC score in patients with PD is not well-established, which is the objective of this study.

Materials and methods

Cross-sectional study with patients on PD, followed up at a University Hospital, between March 2018 and August 2019. PhA was evaluated by unifrequency bioimpedance (BIA). The CAC score was calculated based on cardiovascular computed tomography, considering positive when greater than or equal to 100 Agatston and negative when less than 100 Agatston.

Results

We evaluated 44 patients on dialysis, with a mean age of 56 years and median time on dialysis therapy was 11.7 months. In the statistical analysis, a significant association was only observed between the CAC score and the PhA.

Conclusion

The PhA is associated with a positive CAC score in patients with PD, and despite other factors, may be useful as a risk marker for coronary artery disease in this population.

Midkine release during hemodialysis is predictive of hypervolemia and associates with excess (cardiovascular) mortality in patients with end-stage renal disease: a prospective study

Background

In end-stage renal disease, a high cardiovascular risk profile and endothelial damage prevails. The heparin-binding growth factor midkine stimulates neo-angiogenesis in ischemic diseases, coordinates neutrophil influx, and raises blood pressure through stimulated angiotensin synthesis.

Methods

We determined changes of midkine serum levels during hemodialysis sessions under the assumption that endothelial cell-derived midkine is released. Periprocedural differences (∆midkine) were calculated and correlated with cardiovacular biomarkers and fluid status (clinical assessment, V. cava collapse, comet tail phenomenon), cardiovascular morbidities, mortality rates. Blood was collected before and after dialysis from hemodialysis patients (n = 171; diabetes: n = 70; hypervolemia: n = 83; both: n = 32).

Results

Baseline midkine levels were ~ fourfold elevated compared to healthy controls (n = 100). Further, on average a tenfold rise was detected during dialysis, the extent of which was partially related to non-fractionated heparin application (r² = 0.17). Inter-individual differences were highly reproducible. Hypervolemic patients responded with a less than average rise in midkine levels during dialysis (p < 0.02), this difference became more obvious with co-existing diabetes (p < 0.001 for long dialysis-free interval) and was confirmed in an independently enrolled dialysis cohort (n = 88). In Kaplan Meier survival curves, low delta midkine levels correlated with cardiovascular/overall mortality rates, similar to elevated uPAR levels, whereas other markers (NTproANP, galectin, tenascin-C) were less predictive. Following intervention with successful fluid removal in hypervolemic dialysis patients to optimize fluid homeostasis, midkine values increased (p < 0.002), which was not observed in patients that failed to decrease weight.

Conclusion

Thus, for dialysis patients inadequate periprocedural midkine upregulation is linked with hypervolemia and associates with cardiovascular events.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11255-022-03141-4.

Echocardiographic left ventricular hypertrophy and geometry in Chinese chronic hemodialysis patients: the prevalence and determinants

Background

To investigate the prevalence of left ventricular hypertrophy (LVH) and explore left ventricular geometry in maintenance hemodialysis (MHD) patients, and to explore the risk factors of LVH which is an important predictor of cardiovascular events.

Methods

The subjects were patients who are on MHD for more than 3 months in Peking University People's Hospital from March 2015 to February 2017. Demographic and clinical data were retrospectively collected. Left ventricular mass was measured by echocardiography. LVH is defined by Left ventricular mass index (LVMI) > 115 g/m² for men and > 95 g/m² in women. LVMI and relative wall thickness were used to determine left ventricular geometry. Logistic regression was used to analyze the risk factors of LVH.

Results

Altogether, 131 patients including 77 males were enrolled. The median age was 60 (47, 69) years, with a median dialysis vintage of 48 (18, 104) months. There were 80 patients with LVH, the prevalence rate was 61.1%, and 66.3% of them were moderate to severe LVH. We found that (1) most of the patients were concentric hypertrophy; (2) one-third of the patients were concentric remodeling; (3) only 4 cases with normal geometry. The pre-dialysis serum sodium level and time average pre-dialysis systolic blood pressure (SBP) were independent risk factors of LVH.

Conclusion

LVH is prevalent in MHD patients. Concentric hypertrophy and concentric remodeling are the most common geometric patterns. Attention should be paid to long-term pre-dialysis SBP management and pre-dialysis sodium control as they might be potentially modifiable risk factors for LVH.

Peritoneal-Membrane Characteristics and Hypervolemia Management in Peritoneal Dialysis: A Randomized Control Trial

Excessive bodily-fluid retention is the major cause of hypertension and congestive heart failure in patients with end-stage renal disease. Compared to hemodialysis, peritoneal dialysis (PD) uses the abdominal peritoneum as a semipermeable dialysis membrane, providing continuous therapy as natural kidneys, and having fewer hemodynamic changes. One major challenge of PD treatment is to determine the dry weight, especially considering that the speed of small solutes and fluid across the peritoneal membrane varies among individuals; considerable between-patient variability is expected in both solute transportation and ultrafiltration capacity. This study explores the influence of peritoneal-membrane characteristics in the hydration status in patients on PD. A randomized control trial compares the bioimpedance-assessed dry weight with clinical judgment alone. A high peritoneal membrane D/P ratio was associated with the extracellular/total body water ratio, dialysate protein loss, and poor nutritional status in patients on PD. After a six-month intervention, patients with monthly bioimpedance analysis (BIA) assistance had better fluid (−1.2 ± 0.4 vs. 0.1 ± 0.4 kg, p = 0.014) and blood-pressure (124.7 ± 2.7 vs. 136.8 ± 2.8 mmHg, p < 0.001) control; however, hydration status and blood pressure returned to the baseline after we prolonged BIA assistance to a 3-month interval. The dry-weight reduction process had no negative effect on residual renal function or peritoneal-membrane function. We concluded that peritoneal-membrane characteristics affect fluid and nutritional status in patients on PD, and BIA is a helpful objective technique for fluid assessment for PD.

Impact of dialysis modality on major adverse cardiovascular events and all-cause mortality: a national population-based study

BACKGROUND

Only few studies with inconsistent results comparing the relative risk of cardiac mortality between peritoneal dialysis (PD) and hemodialysis (HD). Switches between renal replacement therapy (RRT) modalities render objective assessment of survival benefits a greater challenge.

METHODS

Data were retrieved from Taiwan's National Health Insurance Database from 1 January 2006 to 31 December 2015. We included 13 662 and 41 047 long-term dialysis patients in a propensity score matching study design and a time-varying study design, respectively, to compare major adverse cardiovascular events (MACEs) between patients receiving PD and HD. We also included 109 256 dialysis patients to compare the all-cause mortality among different RRT modalities.

RESULTS

For MACE, the hazard ratio (HR) for PD patients compared to HD patients was 0.95 [95% confidence interval (CI) 0.89-1.02] in the propensity score study design and 1.06 (95% CI 1.01-1.12) in the time-varying study design. For all-cause mortality, the HR for PD patients compared to HD patients was 1.09 (95% CI 1.05-1.13) in the propensity score study design and 1.13 (95% CI 1.09-1.17) in the time-varying study design. The HR for death was higher at a level of statistical significance for females (1.21, 95% CI 1.15-1.28), patients ≥65 years old (1.30, 95% CI 1.24-1.36) and diabetes mellitus (DM; 1.28, 95% CI 1.22-1.34).

CONCLUSIONS

The HR for MACE is significantly higher among PD patients in time-varying design analysis. In addition, all-cause mortality was higher in PD patients compared to patients with HD, especially in those who were aged ≥65 years, female or DM.

The occurrence and potential predictive factors of major adverse cardiac and cerebral events in end-stage renal disease patients on continuous ambulatory peritoneal dialysis: A prospective cohort study

Major adverse cardiac and cerebral events (MACCE) are common complications, which prolong hospitalization and increase mortality rate in end-stage renal disease (ESRD) patients who underwent continuous ambulatory peritoneal dialysis (CAPD). Therefore, this study aimed to investigate MACCE occurrence and its potential predictive factors in those patients.In this prospective cohort study, 196 diagnosis of ESRD patients who underwent CAPD treatment in our hospital were eligible, and their clinical data (including demographic data and biochemical indexes) were documented. Besides, their MACCE occurrence was assessed within 3-year follow-up period.In patients, 1-, 2-, and 3-year MACCE occurrence rates were 5.1%, 11.7%, and 14.8%, respectively. Meanwhile, the mean duration of accumulating MACCE occurrence was 33.1 (95% confidence interval: 32.0-34.2) months. Furthermore, age, peritoneal dialysis duration (PDD), C-reactive protein (CRP), fasting blood glucose (FBG) and total cholesterol high correlated with increased accumulating MACCE occurrence, while high-density lipoprotein cholesterol (HDL-C) high correlated with decreased accumulating MACCE occurrence. Notably, by further multivariate Cox's proportional hazard regression analysis, age, PDD, CRP, serum uric acid, and FBG high were independent predictive factors for raised accumulating MACCE occurrence, while HDL-C high was an independent predictive factor for attenuated accumulating MACCE occurrence.MACCE are common; besides, age, peritoneal dialysis duration, C-reactive protein, serum uric acid, fasting blood glucose, and high-density lipoprotein cholesterol serve as potential markers for indicating MACCE in ESRD patients who underwent CAPD.

Methodology of Assessment of Fluid Status and Ultrafiltration Problems

Loss of sodium and water excretion with disruption of volume homeostasis is a crucial abnormality of end-stage renal failure. Fluid management is a fundamental function of dialysis therapy, but studies show frequent occult fluid overload, hypertension, and cardiac dysfunction in peritoneal dialysis. A rigorous approach to fluid management in PD can achieve excellent fluid, hypertension, and cardiovascular results in clinical practice. The present article explores the reasons for fluid overload and poor ultrafiltration in peritoneal dialysis patients and discusses optimal assessment and management of these problems.

Body Composition Analysis Techniques in Adult and Pediatric Patients: How Reliable are They? How Useful are they Clinically?

Complex abnormalities of body composition occur in peritoneal dialysis (PD). These abnormalities reflect changes in hydration, nutrition, and body fat, and they are of major clinical significance. Clinical assessment of these body compartments is insensitive and inaccurate. Frequently, simultaneous changes of hydration, wasting, and body fat content can occur, confounding clinical assessment of each component. Body composition can be described by models of varying complexity that use one or more measurement techniques. “Gold standard” methods provide accurate and precise data, but are not practical for routine clinical use. Dual energy X-ray absorptiometry allows for measurement of regional as well as whole-body composition, which can provide further information of clinical relevance. Simpler techniques such as anthropometry and bioelectrical impedance analysis are suited to routine use in clinic or at the bedside, but may be less accurate. Body composition methodology sometimes makes assumptions regarding relationships between components, particularly in regard to hydration, which may be invalid in pathologic states. Uncritical application of these methods to the PD patient may result in erroneous interpretation of results. Understanding the foundations and limitations of body composition techniques allows for optimal application in clinical practice.

The effect of sodium exchange and dialytic biochemical parameters on blood pressure, arterial stiffness, and endothelial functions in patients with peritoneal dialysis

OBJECTIVE

This study aimed to investigate the relationship between fluid and sodium excretion and blood pressure, echocardiographic parameters, and arterial stiffness in peritoneal dialysis (PD) patients and to evaluate the effect of sodium excretion on patients' survival.

METHOD

This study was conducted as a single-centered, prospective study in the Department of Nephrology in Erciyes University. The patients included in the study were followed up for 3 years. Seventy PD patients were included in the study. We recorded demographic characteristics, biochemical parameters, urine and peritoneal ultrafiltration volumes, peritoneal equalization tests, ambulatory blood pressure measurements, and echocardiographic measurements. We measured the amount of total sodium excretion of the patients and arterial stiffness using pulse wave velocity (PWV). Patients were divided into two groups based on the amount of total sodium excretion: low group and high group. We compared these groups in terms of cardiac and biochemical parameters.

RESULTS

When demographic data and biochemical values were compared, there was no significant difference between the two groups. NT-proBNP level, systolic blood pressure, and mean arterial pressure were significantly higher in the low group (p: 0.02, p: 0.031, p: 0.05, respectively). Net ultrafiltration was significantly higher in the high group (p: 0.03), was also found to be high in patients with high sodium excretion (p: 0.001). Negative correlations were found between sodium excretion and net ultrafiltration, NT-Pro BNP, and PWV. At the end of the 3-year follow-up, the survival rate was shorter and the mortality rate was higher in the low group (p: 0.042).

DISCUSSION AND CONCLUSION

Fluid status in PD patients can affect arterial stiffness both directly and through hypertension. Correction of hypervolemia has the potential to not only prevent hypertension and left ventricular hypertrophy, but also to improve arterial stiffness, a well-known cardiovascular risk factor. The mortality rate was higher in PD patients with low total sodium excretion. Therefore, these patients should be followed more closely to ensure volume control.

Effect of remote patient management in peritoneal dialysis on haemodynamic and volume control

AIM

Reduced treatment compliance in patients with peritoneal dialysis facilitates the development of fluid overload and as a result increased blood pressure and vascular stiffness in the long term. We aimed to evaluate blood pressure change and anti-hypertensive needs of patients within 1 year after the changeover to remote monitoring automated peritoneal dialysis (RM-APD) and compare the effect of RM-APD and continuous ambulatory peritoneal dialysis (CAPD) on peripheral and central haemodynamic parameters, volume status of patients and anti-hypertensive drug needs.

METHODS

This was an observational and cross-sectional study. We enrolled 15 patients performing CAPD, 20 patients performing RM-APD, and 38 age, and gender-matched healthy control. We measured pulse wave velocity to assess arterial stiffness, peripheral and central haemodynamic parameters. We measured the volume status of participants via bioimpedance spectroscopy.

RESULTS

The mean excess hydration of patients who underwent CAPD were higher than those who performed RM-APD and healthy control (P = .02). We found that mean diastolic blood pressure, heart rate, central systolic and diastolic blood pressure, and central pulse pressure were significantly different between the RM-APD, CAPD and healthy control (P = .02, P = .05, P = .007, P = .05 and P = .005, respectively). Post hoc analysis of these results showed that the differences between the groups were caused by the healthy control group and the patients with underwent CAPD. Daily anti-hypertensive drug count in patients with performing RM-APD was reduced over time (P < .001).

CONCLUSION

The RM-APD provides better control of peripheral blood pressure and decrease of central haemodynamic parameters via controlling the excess body water.

Influence of Fluid Status on Techniques Used to Assess Body Composition in Peritoneal Dialysis Patients

Objective

A reliable assessment of nutritional state in peritoneal dialysis (PD) patients is of great importance. Nevertheless, techniques used to assess body composition in patients on PD may be affected by abnormalities in fluid status. The primary aim of the present study was to compare different techniques used to evaluate body composition and to assess the influence of fluid status on the assessment of body composition. The secondary aim was to assess the relevance of handgrip muscle strength in the nutritional evaluation of the patient.

Methods

In 40 PD patients, dual-energy x-ray absorptiometry (DEXA), multifrequency bioimpedance analysis (MF-BIA), and anthropometry were compared with respect to the evaluation of body composition [fat mass and lean body mass (LBM; by DEXA), and fat-free mass (FFM; by MF-BIA, anthropometry]. The influence of fluid status on the measurement of LBM/FFM by the various techniques was assessed by their relation to left ventricular end-diastolic diameter (LVEDD), assessed by echocardiography, and by estimating the ratio between extracellular water (ECW) and total body water (TBW), assessed by bromide and deuterium dilution, with LBM (DEXA). The relevance of handgrip muscle strength as a nutritional parameter was assessed by its relation to LBM and other nutritional parameters.

Results

Despite highly significant correlations, wide limits of agreement between the various techniques were present with respect to assessment of body composition (expressed as % body weight) and were most pronounced for anthropometry: LBM (DEXA) – FFM (MF-BIA) = 3.4% ± 12.2%; LBM (DEXA) – FFM (anthropometry) = –5.7% ± 7.8%; fat mass (DEXA – MF-BIA) = –4.2%± 7.9%; fat mass (DEXA – anthropometry) = 2.9% ± 7.2%. The ratio between ECW and LBM (DEXA) was 0.36 ± 0.08 L/kg (range 0.25 – 0.67 L/kg), and the ratio between TBW and LBM was 0.75 ± 0.06 L/kg (range 0.63 – 0.86 L/kg), which shows the variability in hydration state of LBM/FFM between individual patients. LBM/FFM measured by all three techniques was significantly related to LVEDD, suggesting an important influence of hydration state on this parameter. Handgrip muscle strength was significantly related to LBM/FFM, as measured by all three techniques, but not to other nutritional parameters.

Conclusion

Wide limits of agreement were found between various techniques used to assess body composition in PD patients. The assessment of body composition was strongly influenced by hydration state. The handgrip test is related to body composition, but not to other nutritional parameters.

A Ward-Based Procedure for Assessment of Fluid Status in Peritoneal Dialysis Patients Using Bioimpedance Spectroscopy

♦ Objective

This study was carried out to evaluate a procedure for converting bioimpedance spectroscopy (BIS) data to a clinically useful measure of fluid status that is easily interpreted by nursing staff and patients.

♦ Design

The ratio of extracellular water (ECW) to total body water (TBW) in a cohort of peritoneal dialysis (PD) patients was compared with the distribution for normal control subjects. The result was expressed as the difference between the measured ECW/TBW ratio and the mean ratio for age- and sex-matched controls divided by the standard deviation for the controls (the “hydration score”). Where possible, interventions were made to reduce the target weight in patients with a hydration score greater than +2.0.

♦ Setting

This clinical study was carried out in the nurseled outpatient PD unit at St. James's University Hospital. BIS measurements were carried out during routine clinic visits. The data for the control subjects were obtained in a range of settings in the UK and the Czech Republic.

♦ Patients

31 PD patients (21 M, 10 F; aged 19 – 78 years) who came to the PD unit for routine procedures during the study participated.

♦ Results

The mean hydration score for PD patients was significantly higher than for the control subjects (+1.3 vs 0.0, p < 0.0001). 11 (35%) patients had a hydration score greater than +2.0, compared with only 2.5% of the controls; systolic blood pressure was greater than 130 mmHg in only two of these patients. After a 3-month follow-up, a weight reduction of 3.6 ± 2.3 kg had been achieved in 7 patients through modality change and implementation of prescription changes, with no adverse effects.

♦ Conclusions

Although this was a small study, all the data collected indicated that the hydration score provides a reliable indication of fluid status in PD patients. BIS measurements are now carried out at 6-month intervals and are used to monitor the effect of interventions.

The Influence of Dialytic Modality on Arterial Stiffness, Pulse Wave Reflections, and Vasomotor Function

Background

Measurements of aortic stiffness [aortic pulse wave velocity (PWV) and augmentation index (AIx)] have been established as powerful predictors of survival on hemodialysis (HD). Abnormal endothelial-dependent and endothelial-independent vascular reactivity and increased arterial stiffness are commonly described in HD patients. There is, however, a lack of information on the comparative impact of different renal replacement therapies (RRTs) on PWV and AIx, and how these different methods might influence endothelial-dependent abnormal vasodilatation.

Objective

To describe in a cross-sectional design arterial compliance and distensibility in continuous ambulatory peritoneal dialysis (CAPD) versus HD versus renal transplant (RTx) patients, compared with age- and blood pressure-matched essential hypertensive controls. The PWV and aortic AIx were determined from contour analysis of arterial waveforms recorded by applanation tonometry in 40 CAPD, 41 HD, 20 RTx patients (with normal serum creatinine), and 20 controls with essential hypertension (all normotensive under treatment). Endothelial-dependent and endothelial-independent vascular reactivities were assessed by changes in AIx following challenges with inhaled salbutamol and sublingual nitroglycerin respectively.

Results

CAPD patients had significantly stiffer arteries than all other categories. The PWV was 8.29 ± 1.09 m/second in CAPD patients, significantly higher ( p < 0.05) compared to HD subjects (7.19 ± 1.87 m/s). Both dialysis subgroups had significantly higher PWV values compared to RTx patients (6.59 ± 1.62 m/s) and essential hypertensive controls (6.34 ± 1.32 m/s), p < 0.05. The AIx had a profile similar to PWV in different RRTs. All groups with the exception of CAPD subjects had a significant decrease in AIx following salbutamol. Moreover, the vasodilatation induced by either nitroglycerin or salbutamol was significantly blunted compared to HD. Overall, both dialysis categories had more abnormal responses compared to RTx patients and essential hypertensive controls.

Conclusion

CAPD is associated with stiffer arteries and more profoundly abnormal endothelial-dependent vasomotor function, compared to matched HD subjects. These differences in arterial physical properties might explain differences seen in cardiac structure and function between the RRTs.

Relationship of Demographic, Dietary, and Clinical Factors to the Hydration Status of Patients on Peritoneal Dialysis

Objectives

To establish which clinical factors are associated with an increased proportion of extracellular fluid (ECF) in peritoneal dialysis (PD) patients.

Design

A single-center, cross-sectional analysis of 68 stable PD patients.

Method

Bioelectrical impedance measurements (RJL, single frequency; RJL Systems, Clinton, Michigan, USA) of resistance and reactance were used to determine the proportion of ECF comprising total body water (TBW) in 68 stable PD patients attending for routine clearance and membrane studies. All patients underwent detailed dietetic, adequacy, and membrane function tests. Blood pressure and antihypertensive requirements were also documented.

Results

Significant gender differences in body composition were observed, such that women had lower absolute TBW and fat-free mass per kilogram body weight, but proportionately more ECF for a given TBW, mean ECF:TBW 0.5 ± 0.03 versus 0.44 ± 0.05, p < 0.005. In view of this, patients were split into two groups, defined as “over-” or “normally” hydrated, either by using the single discriminator (median ECF:TBW = 0.47) for the whole population, which resulted in groups distorted by gender, or by using different discriminators according to gender (women: 0.49, men 0.45). In both analyses, overhydrated patients were older, had significantly lower plasma albumin, less total fluid removal per kilogram body weight, and higher peritoneal solute transport. When split by a single discriminator, the overhydrated patients had lower sodium removal and significantly less intracellular fluid volume due to an excess of women in this group who also had less residual function and had been on dialysis longer. Using gender-specific discrimination, overhydrated patients were heavier due to expansion of the ECF volume: 20 ± 4.1 L versus 16 ± 3.3 L, p < 0.001. Stepwise multivariate analysis found age ( p = 0.001), albumin ( p = 0.009), and fluid losses per kilogram body weight ( p = 0.025) to be independent predictors of gender-adjusted hydration status. Sodium intake did not vary according to hydration status.

Conclusion

Gender influences the assessment of hydration status of PD patients when employing bioimpedance, such that women tend to have more ECF. Taking this into account, age, albumin, and achieved fluid removal appear to be independently associated with hydration status, whereas peritoneal solute transport is not. Advice on dietary sodium should take account of hydration status and achievable losses.

Chronic Inflammation in Peritoneal Dialysis: The Search for the Holy Grail?

Mortality and morbidity in chronic kidney disease (CKD) patients are unacceptably high. The annual mortality rate due to cardiovascular disease (CVD) is approximately 9%, which, for the middle-aged person, is at least 10- to 20-fold higher than for the general population. Classic risk factors for CVD are highly prevalent in CKD patients, but they cannot fully account for the excessive rate of CVD in this population. Instead, it has become increasingly clear that nontraditional risk factors, such as systemic inflammation, may play a key role in the development of atherosclerosis. It is well established that inflammatory markers are very powerful predictors of high CVD morbidity and mortality not only in the general population, but particularly in CKD patients. Signs of a sustained low-grade inflammation, such as increased levels of C-reactive protein (CRP), are present in the majority of stage 5 CKD patients, even in patients in clinically stable condition, and they are also commonly observed after the initiation of dialysis therapy. Dialysis therapy — hemodialysis as well as peritoneal dialysis (PD) — may itself contribute to systemic inflammation. Local intraperitoneal inflammation can also occur in patients treated with PD. These local effects may result in a low-grade inflammation, caused by the bioincompatibility of conventional glucose-based dialysis fluids, to intense inflammation associated with peritonitis. Given these circumstances, it is reasonable to hypothesize that strategies aiming to reduce inflammation are potentially important and novel, and could serve to reduce CVD, thereby lowering morbidity and mortality in patients with CKD. In this review we provide information supporting the hypothesis that systemic inflammation is tightly linked to the most common complications of CKD patients, in particular those on PD, and that local inflammation in PD may contribute to various related complications. The aims of this review are to discuss the reasons that make inflammation an attractive target for intervention in CKD, the particular aspects of the inflammation–CVD axis during PD treatment that are likely involved, and possible means for the detection and management of chronic inflammation in PD patients.

Blood Pressure, Volume, and Sodium Control in an Automated Peritoneal Dialysis Population

Objectives

To examine the control of blood pressure and volume, and the role of sodium removal in a single, large, contemporary, automated peritoneal dialysis (APD) population where icodextrin is used liberally and there is a policy to avoid long duration glucose-based daytime dwells.

Design

Observational cross-sectional study.

Setting

A university hospital.

Patients

56 APD patients, with a mean duration on peritoneal dialysis of 1.9 years; 50% were prescribed icodextrin.

Main Outcome Measures

Blood pressure, extracellular water volume (ECW)-to-intracellular water volume (ICW) ratio, and total (peritoneal and urinary) sodium removal.

Results

Sodium Removal: Mean total sodium removal, while low at 102.9 ± 64.6 mmol/day, showed a wide range, with 41% having a sodium removal of >120 mmol/day. Total sodium removal correlated with total body water, ECW, and ICW ( p < 0.001, p < 0.001, p < 0.025, respectively), as well as with height and weight ( p < 0.06, p < 0.01 respectively). On multivariate analysis, only ultra-filtration volume and urine volume were significantly associated with total sodium removal ( r2 = 0.67, p < 0.0001 for both). There was also a correlation between sodium removal and urea nitrogen appearance ( r2 = 0.31, p < 0.001), with urea nitrogen appearance in turn being closely correlated with ICW ( p < 0.001). Volume Status: The ECW/ICW ratio was 0.88 ± 0.17, which was not significantly different to that found in hemodialysis patients without clinical evidence of fluid overload, either predialysis (0.96 ± 0.16) or postdialysis (0.92 ± 0.16); p = 0.07 and 0.36 respectively. Blood Pressure: Mean ± standard deviation systolic blood pressure (BP) was 111.9 ± 18.2 mmHg and diastolic BP was 63.3 ± 11.9 mmHg, with only 4 (7%) patients having a systolic BP > 140 mmHg and 1 (2%) having a diastolic BP > 80 mmHg. Median number of antihypertensives was 1 per day. Blood pressure control and ECW/ICW ratio were similar in those with sodium removal >120 mmol/day compared to those with sodium removal ≤120 mmol/day ( p = 0.39 for SBP, p = 0.70 for diastolic B P, p = 0.24 for ECW/ICW).

Conclusions

We have shown that good blood pressure and volume control is achievable in a large contemporary APD population with liberal use of icodextrin and avoidance of long daytime glucose-based dwells. Neither low nor high sodium removal was associated with more frequent hypertension or volume expansion.

Are We Underestimating the Problem of Ultrafiltration in Peritoneal Dialysis Patients?

Background

Accurate measurement of ultrafiltration (UF) is important to improve the morbidity and mortality of peritoneal dialysis (PD) patients. The introduction of “flush-before-fill” PD systems has led to improved peritonitis rates. Partly to compensate for dialysate lost during flush-before-fill, extra dialysate was added to each PD bag. A 2-L PD bag now contains a mean volume of 2.225 L. That overfill volume might be erroneously measured as UF. We previously studied how this confounding factor might be affecting the diagnosis of UF failure and found that almost all units were overestimating daily UF by 900 mL. We now repeat the study to determine if the accuracy of UF estimation has improved.

Methods

We conducted a telephone survey of PD units in the UK to determine how drain bags are weighed and how UF is calculated during formal assessment of adequacy and the peritoneal equilibrium test (PET). We also retrospectively analyzed our last 100, 24-hour dialysate collections and PET results to determine the potential clinical impact of overestimating UF.

Results

There has been an improvement since our last study, but 70% of PD units in the UK are still overestimating daily UF in patients on continuous ambulatory PD (CAPD). Half the surveyed units also inaccurately calculate UF during the PET, and 85% were reporting results of PET and 24-hour dialysate collections through the software provided by Baxter Healthcare. By including the overfill volume, 73% of patients with daily UF <750 mL would not be diagnosed as having inadequate daily UF (assuming that all were fluid overloaded and anuric). Similarly, 73% with potential UF failure during the PET (4-hour UF <100 mL) would be missed if overfill volume was misrepresented as UF.

Conclusion

For patients undergoing CAPD, there requires standardization on when drain bags are weighed. Awareness that calculation of UF must exclude overfill volumes has improved but remains poor. The PD Adequest software (Baxter Healthcare, Compton, UK) is widely adopted in the UK and perhaps it could draw attention of users to the potential of UF overestimation in CAPD patients.

Enhanced Ultrafiltration using 7.5% Icodextrin / 1.36% Glucose Combination Dialysate: A Pilot Study

Objective

A pilot study to compare the use of a combination dialysate (7.5% icodextrin / 1.36% glucose) versus icodextrin 7.5% alone for the long dwell in patients on peritoneal dialysis (PD).

Design

A 4-week, prospective, randomized crossover study.

Setting

A large regional renal unit providing treatment for a population of 1.7 million.

Patients

Five patients on continuous ambulatory PD (CAPD) and 3 patients on automated PD.

Main Outcome Measurements

Long-dwell and 24-hour ultrafiltration volumes, body weight, 24-hour ambulatory blood pressure, and antihypertensive / diuretic tablet count.

Results

The use of the combination dialysate resulted in an increase in the median (interquartile range) long-dwell ultrafiltration, from 750 (650 – 828) mL to 1000 (889 – 1100) mL ( p < 0.001), and 24-hour ultrafiltration, from 739 (400 – 1623) mL to 956 (700 – 1750) mL ( p < 0.001). Weight, blood pressure, and tablet count remained unchanged.

Conclusions

The use of the novel combination dialysate resulted in a 33% increase in long-dwell ultrafiltration and a 29% increase in 24-hour ultrafiltration.

Article Commentary: Application of Bioelectrical Impedance to Clinical Assessment of Body Composition in Peritoneal Dialysis

Patients on peritoneal dialysis (PD) develop complex changes in body composition. These changes reflect hydration, nutrition, and body fat, all important elements reflecting patient well-being and efficacy of therapy that should be assessed and monitored as guides to patient management. They are all notoriously difficult to accurately measure in clinical practice and simultaneous abnormalities may obscure detection, as in the malnourished fluid-overloaded patient where body weight is misleadingly stable. Malnutrition is a serious complication in PD that carries an adverse prognosis. Assessment of hydration in PD is important in determining “dry weight” to allow adjustment of dialysis prescription to optimize fluid balance. A number of techniques have been investigated to measure body composition in clinical practice. Of these, bioelectrical impedance analysis (BIA) has attracted most interest and seems to be of greatest promise. Cases illustrating different aspects of the use of BIA in PD patients are described, and the background, possible uses, and limitations of BIA in PD patients are discussed. To be of clinical value, BIA must be used to distinguish between extracellular water (which reflects hydration) and body cell mass, or intracellular water (which declines in wasting and malnutrition). The high precision of BIA is ideally suited to detecting changes in body composition and its main role may be in longitudinal monitoring. However, inaccuracy of absolute measurements and variability of normal values in the general population make precise diagnosis of the degree of normality of body composition in an individual subject a more difficult task for body composition analysis.

Serum BNP Concentration and Left Ventricular Mass in CAPD and Automated Peritoneal Dialysis Patients

Objective

To compare ultrafiltration under continuous ambulatory peritoneal dialysis (CAPD) and automated PD (APD), disclosing potential effects on serum B-type natriuretic peptide (BNP) levels and echocardiographic findings.

Patients and Methods

This cross-sectional clinical study included 32 patients on CAPD and 30 patients on APD without clinical evidence of heart failure or hemodynamically significant valvular heart disease. Peritoneal equilibration tests, BNP levels, and echocardiographic measurements were performed in each subject. BNP measurements were also performed in 24 healthy control subjects.

Results

Patients on APD had lower ultrafiltration and higher values of BNP and left ventricular mass index (LVMI) compared with patients on CAPD (respectively: 775 ± 160 vs 850 ± 265 mL, p = 0.01; 253.23 ± 81.64 vs 109.42 ± 25.63 pg/mL, p = 0.001; 185.12 ± 63.50 vs 129.30 ± 40.95 g/m2, p = 0.001). This occurred despite higher mean dialysate glucose concentrations and far more extensive use of icodextrin in the APD group.

Conclusion

Treatment with APD is associated with higher plasma BNP levels and LVMI compared to CAPD. This may be the result of chronic fluid retention caused by lower ultra-filtration in APD patients.

Fluid Status and its Management in Japanese Peritoneal Dialysis Patients

This article reviews published studies related to fluid status of Japanese peritoneal dialysis (PD) patients and its impact on technique and patient survival. In addition, some specifics related to clinical background that potentially influence fluid status are described. According to a multi-center survey conducted in Japan, nearly 25% of Japanese PD patients are overhydrated. Available data indicate that a high salt diet may conceivably play an important role in the pathogenesis of fluid overload in Japanese PD patients, and it in turn negatively impacts patient prognosis. Because of the generally adopted policy among Japanese PD experts to avoid regular use of 3.86% glucose solution, icodextrin solution is now used in more than one third of all patients. Other means of managing fluid overload, such as drug therapy, combination (complementary) therapy with hemodialysis, and low sodium PD solution, are also explored and summarized in this article.

High Peritoneal Permeability is Not Associated with Higher Mortality or Technique Failure in Patients on Automated Peritoneal Dialysis

Background

Patients on continuous ambulatory peritoneal dialysis (CAPD) who have high small-molecule peritoneal transport have increased mortality.

Objective

To investigate the impact of baseline peritoneal transport characteristics on patient and technique survival in incident peritoneal dialysis (PD) patients, most of whom are on automated PD (APD), with the use of icodextrin.

Design

Retrospective observational cohort study.

Setting

A single PD unit.

Patients and Methods

193 new patients that began PD between January 2000 and September 2004, and had an initial peritoneal equilibration test within 6 months of commencement of PD. Patients were divided into low (L), low average (LA), high average (HA), and high (H) peritoneal transport groups. Death-censored technique failure and patient survival were examined.

Results

Of the 193 patients, 151 (78.1%) were on APD or on APD with icodextrin or on CAPD with icodextrin. At the end of 1, 3, and 5 years, patient survival was 91%, 82%, and 67% in LA group; 95%, 77%, and 69% in HA group; and 96%, 71%, and 71% in H group. Technique survival was 100%, 90%, and 77% in LA group; 96%, 84%, and 72% in HA group; and 92%, 87%, and 77% in H group. High peritoneal permeability did not predict worse patient survival or technique failure, while age, diabetes, a lower glomerular filtration rate, and high body mass index (≥ 30 kg/m2) were independent predictors of death.

Conclusion

This study suggests that higher peritoneal transport is not a significant independent risk factor for either mortality or death-censored technique failure. The favorable outcome for high transporters in this study may be due to improved management of volume status by the increased use of APD and the use of icodextrin-based dialysis fluid.

Combination of Crystalloid (Glucose) and Colloid (Icodextrin) Osmotic Agents Markedly Enhances Peritoneal Fluid and Solute Transport during the Long PD Dwell

Background

Fluid and sodium removal is often inadequate in peritoneal dialysis patients with high peritoneal solute transport rate, especially when residual renal function is declining.

Method

We studied the effects of using simultaneous crystalloid (glucose) and colloid (icodextrin) osmotic agents on the peritoneal transport of fluid, sodium, and other solutes during 15-hour single-dwell exchanges using 3.86% glucose, 7.5% icodextrin, and a combination fluid with 2.61% glucose and 6.8% icodextrin in 7 prevalent peritoneal dialysis patients with fast peritoneal solute transport rate.

Results

The combination fluid enhanced net ultrafiltration (mean 990 mL) and sodium removal (mean 158 mmol) compared with 7.5% icodextrin (mean net ultrafiltration 462 mL, mean net sodium removal 49 mmol). In contrast, the 3.86% glucose-based solution yielded negligible ultra-filtration (mean -85 mL) and sodium removal (mean 16 mmol). The combination solution resulted in significantly improved urea (+41%) and creatinine (+26%) clearances compared with 7.5% icodextrin.

Conclusion

A solution containing both crystalloid (glucose 2.61%) and colloid (icodextrin 6.8%) osmotic agents enhanced fluid removal by twofold and sodium removal by threefold compared with 7.5% icodextrin solution during a dwell of 15 hours, indicating that such a combination solution could represent a new treatment option for anuric peritoneal dialysis patients with high peritoneal solute transport rate.

Phase Angle Predicts Arterial Stiffness and Vascular Calcification in Peritoneal Dialysis Patients

Objectives

Fluid overload (FO) is frequently present in peritoneal dialysis (PD) patients and is associated with markers of malnutrition, inflammation, and atherosclerosis/calcification (MIAC) syndrome. We examined the relationships in stable PD patients between phase angle (PhA) and the spectrum of uremic vasculopathy including vascular calcification and arterial stiffness and between PhA and changes in serum fetuin-A levels.

Methods

Sixty-one stable adult PD patients were evaluated in a cross-sectional study (ST1). Phase angle was measured by multifrequency bioimpedance analysis (InbodyS10, Biospace, Korea) at 50 kHz. Augmentation index (AI), a surrogate marker of arterial stiffness, was assessed by digital pulse amplitude tonometry (Endo PAT, Itamar Medical, Caesarea, Israel). Vascular calcification was assessed by simplified calcification score (SCS). Serum fetuin-A levels were measured by ELISA (Thermo scientific; Waltham, MA, USA). Serum albumin was used as a nutritional marker, and serum C-reactive protein (CRP) was used as an inflammatory marker. The same assessments were carried out longitudinally (ST2) in the first 33 patients who completed 1 year of evaluation in ST1.

Results

In ST1, patients with PhA < 6° had higher CRP levels, AI, and SCS and lower serum albumin and fetuin-A levels, in comparison with patients with PhA ≥ 6°. In addition, PhA was a predictor of both AI ((3 = -0.351, p = 0.023) and SCS > 3 (EXP (B) = 0.243, p = 0.005). In ST2, the increase of PhA over time was associated with decreases in both AI ( r = -0.378, p = 0.042) and CRP levels ( r = -0.426, p = 0.021), as well as with the increase in serum fetuin-A levels ( r = 0.411, p = 0.030).

Conclusions

Phase angle predicts both arterial stiffness and vascular calcification in stable PD patients.

Comparison of risk of stroke in patients treated with peritoneal dialysis and hemodialysis: a systematic review and meta-analysis

Objective: Accumulating evidence has demonstrated that dialysis patients are at increased risk for stroke. However, the impact of dialysis modalities on stroke risk remains controversial. We conducted a systematic review and meta-analysis to determine the effect of peritoneal dialysis (PD) and hemodialysis (HD) on stroke risk. Methods: A systematic search of PubMed, EMBASE, and Web of Science was performed to identify articles comparing the stroke outcomes of dialysis patients. Hazard ratios (HRs) with 95% confidence intervals (95% CIs) were extracted and synthesized to examine stroke outcomes, including ischemic stroke, hemorrhagic stroke, and overall stroke. Results: The search yielded five studies composed of 1,219,245 patients that were evaluated in the final analysis. The results showed that PD was associated with a lower risk for hemorrhagic stroke compared with HD (HR = 0.78; 95% CI: 0.69-0.88; p < 0.001). For ischemic stroke, the results showed that PD was associated with a higher risk compared with HD among the non-Asian patients (HR = 1.13; 95% CI: 1.05-1.23; p = 0.002), but there were no significant differences between PD and HD for the Asian patients. Similarly, there were no significant differences between the effects of the PD and HD approaches on overall stroke risk. Conclusions: We observed that PD patients were less likely to develop hemorrhagic stroke than HD patients, and the risk for ischemic stroke was significantly higher for PD patients than for HD patients among the non-Asian patients. However, our findings could be biased due to the heterogeneity of the included studies.

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

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

The efficacy of managing fluid overload in chronic peritoneal dialysis patients by a structured nurse-led intervention protocol

Background

Extracellular volume overload is a common problem in peritoneal dialysis (PD) patients and is associated with excessive mortality. We determine the effectiveness of treating PD patients with extracellular volume overload by a structured nurse-led intervention program.

Methods

The hydration status of PD patients was screened by bioimpedance spectroscopy (BIS). Fluid overload was defined as overhydration volume ≥ 2 L. Patients were classified into Symptomatic and Asymptomatic Groups and were managed by a structured nurse-led intervention protocol that focused on education and motivation. Hypertonic cycles were given for short term symptom relief for the Symptomatic group. Patients were followed for 12 weeks for the change in volume status, blood pressure, knowledge and adherence as determined by standard questionnaires.

Results

We recruited 103 patients (53 Symptomatic, 50 Asymptomatic Group. There was a significant reduction in overhydration volume 4 weeks after intervention, which was sustained by week 12; the overall reduction in overhydration volume was 0.96 ± 1.43 L at 4 weeks, and 1.06 ± 1.70 L at 12 weeks (p < 0.001 for both). The improvement was significant for both Symptomatic and Asymptomatic Groups. There was a concomitant reduction in systolic blood pressure in the Asymptomatic (146.9 ± 20.7 to 136.9 ± 19.5 mmHg, p = 0.037) but not Symptomatic group. The scores of knowledge, adherence to dietary control and advices on daily habit at week 4 were all significantly increased, and the improvement was sustained at week 12.

Conclusions

The structured nurse-led intervention protocol has a lasting benefit on the volume status of PD patients with extracellular volume overload. BIS screening allows prompt identification of volume overload in asymptomatic patients, and facilitates a focused effort on this high risk group.

Factors associated with systolic hypertension in peritoneal dialysis patients

Background

Hypertension is common in peritoneal dialysis (PD) patients and associated with adverse outcomes. Besides solute clearance, PD convective clearance is used to control extracellular water (ECW) volume and sodium balance. Previous studies have reported on hypertension in PD patients treated with continuous ambulatory peritoneal dialysis (CAPD) using hypertonic glucose dialysates. However, increasing numbers of PD patients are now treated with automated peritoneal dialysis (APD) and icodextrin dialysates. As such, we wished to explore factors associated with systolic blood pressure (SBP) in a modern cohort to identify targets to improve blood pressure control in PD patients.

Methods

We retrospectively reviewed the results from PD patients attending for peritoneal membrane assessment who had corresponding bioimpedance ECW and brain natriuretic peptide (NT-proBNP) measurements.

Results

We studied 510 PD patients: 317 (72.2%) male, 216 (42.4%) diabetics, median age 59 (47–72) years, and 51% treated by APD with a day-time icodextrin exchange. Mean systolic blood pressure (SBP) was 140 ± 24.8 mmHg. SBP was independently associated with 4-hour dialysate to plasma creatinine ratio (β = 29.5 (95% confidence limits 11.4–47.5, p = 0.001), N-terminal brain natriuretic peptide [β = 11.9 (7.2–16.7), p < 0.001], and daily urine sodium excretion [β = 1.7 (1.0–2.3), p < 0.001].

Conclusion

In the era of APD cyclers and icodextrin, SBP is associated with increased NT-proBNP, a marker of ECW expansion, and faster peritoneal transport, a risk factor for a positive sodium balance, and increased urinary sodium suggestive of higher dietary sodium intake. Patients should be encouraged to restrict sodium intake and PD prescriptions targeted to control ECW to improve SBP control.

Does Routine Bioimpedance-Guided Fluid Management Provide Additional Benefit to Non-Anuric Peritoneal Dialysis Patients? Results from COMPASS Clinical Trial

INTRODUCTION

In peritoneal dialysis (PD) patients, volume overload is related to cardiac dysfunction and mortality, while intravascular volume depletion is associated with a rapid decline in the residual renal function (RRF). This study sought to determine the clinical usefulness of bioimpedance spectroscopy (BIS)-guided fluid management for preserving RRF and cardiac function in PD patients.

SUBJECTS AND METHODS

This is a multicenter, prospective, open-label study that was conducted over a 1-year period (NCT01887262). Non-anuric (urine volume > 500 mL/day) subjects on PD were enrolled. Subjects in the control group received fluid management based on the clinical information alone. Those in the BIS group received BIS-guided fluid management along with clinical information.

RESULTS

The subjects (N = 137, mean age 51.3 ± 12.8 years, 54% male) were randomly assigned to the BIS group (n = 67) or to the control group (n = 70). There were no significant differences between the 2 groups with regard to age, sex ratio, cause of kidney failure, duration of PD, baseline comorbidity, RRF, PD method, or peritoneal transport type. At baseline, the 2 groups were not different in terms of RRF (glomerular filtration rate [GFR], 5.1 ± 2.9 vs 5.5 ± 3.7 mL/min/1.73 m²). After follow-up, changes in the GFR between the 2 groups were not different (-1.5 ± 2.4 vs -1.3 ± 2.6 mL/min/1.73 m², p = 0.593). Over the 1-year study period, both groups maintained stability of various fluid status parameters. Between the 2 groups, there were no differences in the net change of various fluid status parameters such as overhydration (OH) and extracellular water/total body water (ECW/TBW). A net change in ECW over 1 year was slightly but significantly higher in the control group (net increase, 0.57 ± 1.27 vs 0.05 ± 1.63 L, p = 0.047). However, this difference was not translated into an improvement in RRF in the BIS group. There were no differences in echocardiographic parameters or arterial stiffness at the end of follow-up.

CONCLUSION

Routine BIS-guided fluid management in non-anuric PD patients did not provide additional benefit in volume control, RRF preservation, or cardiovascular (CV) parameters. However, our study cannot be generalized to the whole PD population. Further research is warranted in order to investigate the subpopulation of PD patients who may benefit from routine BIS-guided fluid management.

The standard deviation of extracellular water/intracellular water is associated with all-cause mortality and technique failure in peritoneal dialysis patients

PURPOSE

The mortality rate of peritoneal dialysis (PD) patients is still high, and the predicting factors for PD patient mortality remain to be determined. This study aimed to explore the relationship between the standard deviation (SD) of extracellular water/intracellular water (E/I) and all-cause mortality and technique failure in continuous ambulatory PD (CAPD) patients.

METHODS

All 152 patients came from the PD Center between January 1st 2006 and December 31st 2007. Clinical data and at least five-visit E/I ratio defined by bioelectrical impedance analysis were collected. The patients were followed up till December 31st 2010. The primary outcomes were death from any cause and technique failure. Kaplan-Meier analysis and Cox proportional hazards models were used to identify risk factors for mortality and technique failure in CAPD patients.

RESULTS

All patients were followed up for 59.6 ± 23.0 months. The patients were divided into two groups according to their SD of E/I values: lower SD of E/I group (≤0.126) and higher SD of E/I group (>0.126). The patients with higher SD of E/I showed a higher all-cause mortality (log-rank χ (2) = 10.719, P = 0.001) and technique failure (log-rank χ (2) = 9.724, P = 0.002) than those with lower SD of E/I. Cox regression analysis found that SD of E/I independently predicted all-cause mortality (HR  3.551, 95 % CI 1.442-8.746, P = 0.006) and technique failure (HR  2.487, 95 % CI 1.093-5.659, P = 0.030) in CAPD patients after adjustment for confounders except when sensitive C-reactive protein was added into the model.

CONCLUSION

The SD of E/I was a strong independent predictor of all-cause mortality and technique failure in CAPD patients.

The Association between Nutritional Markers and Biochemical Parameters and Residual Renal Function in Peritoneal Dialysis Patients

Residual renal function (RRF) is an important prognostic factor for peritoneal dialysis patients as it influences the quality of life and mortality. This study was conducted to explore the potential factors correlated with RRF. A cross-sectional study was conducted by recruiting 155 patients with residual GFR more than 1mL/min per 1.73m2 at the initiation of peritoneal dialysis. We collected the demographic characteristics, nutritional markers and biochemical parameters of all participants, and analyzed the correlation between these variables and residual GFR as well. The odds ratio of RRF loss associated with each of the nutritional markers and biochemical parameters were estimated by logistic regression model. The residual GFR was negatively correlated with serum phosphate (ORQ3 = 2.67, 95%CI: 1.03-6.92; ORQ4 = 3.45, 95%CI: 1.35-9.04), magnesium (ORQ4 = 3.77, 95%CI: 1.48-3.63), and creatinine (ORQ3 = 2.93, 95%CI: 1.09-7.88; ORQ4 = 8.64 95%CI: 2.79-26.78), while positively associated with normalized protein catabolic rate (ORQ3 = 0.24, 95%CI: 0.09-0.65; ORQ4 = 0.11, 95%CI: 0.03-0.35), 24 hours urine volume(ORQ1 = 22.87, 95%CI: 2.76-189.24; ORQ3 = 0.08, 95%CI: 0.02-0.28) and serum chlorine concentrations (ORQ1 = 5.34, 95%CI: 1.94-14.68; ORQ4 = 0.28, 95%CI: 0.09-0.85), respectively. Our study suggested that the nutritional markers and biochemical parameters, though not all, but at least in part were closely correlated with RRF in peritoneal dialysis patients.

Are Diuretics Underutilized in Dialysis Patients?

While oral diuretics are commonly used in patients with chronic kidney disease for the management of volume and blood pressure, they are often discontinued upon initiation of dialysis. We suggest that diuretics are considerably underutilized in peritoneal dialysis and haemodialysis patients despite numerous potential benefits and few side effects. Moreover, when diuretics are used, optimal doses are not always prescribed. In peritoneal dialysis, the use of diuretics can improve volume status and minimize the need for higher glucose-containing solutions. In patients on haemodialysis, diuretics can help lessen interdialytic weight gain, resulting in decreased ultrafiltration rates and fewer episodes of intradialytic hypotension. This paper will review the mechanism of action of diuretics in patients with renal insufficiency, quantify the risk of side effects and elaborate on the potential advantages of diuretic use in peritoneal dialysis and hemodialysis patients with residual kidney function.

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.

Extracellular volume expansion and the preservation of residual renal function in Korean peritoneal dialysis patients: a long-term follow up study

INTRODUCTION

In chronic peritoneal dialysis patients, preservation of residual renal function (RRF) is a major determinant of patient survival, and maintaining sufficient intravascular volume has been hypothesized to be beneficial for the preservation of RRF. The present study aimed to test this hypothesis using multifrequency bioimpedence analyzer (MFBIA), in Korean peritoneal dialysis patients.

METHODS

A total of 129 patients were enrolled in this study. The baseline MFBIA was checked, and the patients were divided into the following two groups: group 1, extracellular water per total body water (ECW/TBW) < median, group 2, ECW/TBW > median. We followed up the patients, and then we analyzed the changes in the urine output (UO) and the solute clearance (weekly uKt/V) in each group. Data associated with patient and technical survivor were collected by medical chart review. The volume measurement was made using Inbody S20 equipment (Biospace, Seoul, Korea). We excluded the anuric patients at baseline.

RESULT

The median value of ECW/TBW was 0.396. The mean patient age was 49.74 ± 10.01 years, and 62.1 % of the patients were male; most of the patients were on continuous ambulatory peritoneal dialysis (89.1 %). The mean dialysis vintage was 26.20 ± 28.71 months. All of the patients were prescribed hypertensive medication, and 48.5 % of the patients had diabetes. After 25.47 ± 6.86 months of follow up, ΔUO and Δweekly Kt/V were not significantly different in the two groups as follows: ΔUO (-236.07 ± 185.15 in group 1 vs -212.21 ± 381.14 in group 2, p = 0.756); Δ weekly Kt/v (-0.23 ± 0.43 in group 1 vs -0.29 ± 0.49 in group 2, p = 0.461). The patient and technical survivor rate was inferior in the group 2, and in the multivariable analysis, initial hypervolemia was an independent factor that predicts both of the patient mortality [HR 1.001 (1.001-1.086), p = 0.047] and the technical failure [HR 1.024 (1.001-1.048), p = 0.042].

CONCLUSIONS

Extracellular volume expansion, measured by MFBIA, does not help preserve residual renal function, and is harmful for the technical and patient survival in Korean peritoneal dialysis patients.