Transition between peritoneal dialysis modalities: Impact on blood pressure levels and drug prescription in a national multicentric cohort

BACKGROUND

Hypertension is a leading cause of kidney failure, affects most dialysis patients and associates with adverse outcomes. Hypertension can be difficult to control with dialysis modalities having differential effects on sodium and water removal. There are two main types of peritoneal dialysis (PD), automated peritoneal dialysis (APD) and continuous ambulatory peritoneal dialysis (CAPD). It is unknown whether one is superior to the other in controlling blood pressure (BP). Therefore, the aim of our study was to analyse the impact of switching between these two PD modalities on BP levels in a nationally representative cohort.

METHODS

This was a cohort study of patients on PD from 122 dialysis centres in Brazil (BRAZPD II study). Clinical and laboratory data were collected monthly throughout the study duration. We selected all patients who remained on PD at least 6 months and 3 months on each modality at minimum. We compared the changes in mean systolic/diastolic blood pressures (SBP/DBP) before and after modality transition using a multilevel mixed-model where patients were at first level and their clinics at the second level.

RESULTS

We analysed data of 848 patients (814 starting on CAPD and 34 starting on APD). The SBP decreased by 4 (SD 22) mmHg when transitioning from CAPD to APD (p < 0.001) and increased by 4 (SD 21) mmHg when transitioning from APD to CAPD (p = 0.38); consistent findings were seen for DBP. There was no significant change in the number of antihypertensive drugs prescribed before and after transition.

CONCLUSIONS

Transition between PD modalities seems to directly impact on BP levels. Further studies are needed to confirm if switching to APD could be an effective treatment for uncontrolled hypertension among CAPD patients.

Peritoneal and Urinary Sodium Removal in Refractory Congestive Heart Failure Patients Included in an Ambulatory Peritoneal Dialysis Program: Valuable for Monitoring the Course of the Disease

INTRODUCTION

Spot urinary sodium emerged as a useful parameter for assessing decongestion in patients with congestive heart failure (CHF). Growing evidence endorses the therapeutic role of continuous ambulatory peritoneal dialysis (CAPD) in patients with refractory CHF and kidney disease. We aimed to examine the long-term trajectory of urinary, peritoneal, and total (urinary plus peritoneal) sodium removal in a cohort of patients with refractory CHF enrolled in a CAPD program. Additionally, we explored whether sodium removal was associated with the risk of long-term mortality and episodes of worsening heart failure (WHF).

METHODS

We included 66 ambulatory patients with refractory CHF enrolled in a CAPD program in a single teaching center. 24-h peritoneal, urinary, and total sodium elimination were analyzed at baseline and after CAPD initiation. Its trajectories over time were calculated using joint modeling of longitudinal and survival data. Within the framework of joint frailty models for recurrent and terminal events, we estimated its prognostic effect on recurrent episodes of WHF.

RESULTS

At the time of enrollment, the mean age and estimated glomerular filtration rate were 72.8 ± 8.4 years and 28.5 ± 14.3 mL/min/1.73 m2, respectively. The median urinary sodium at baseline was 2.34 g/day (1.40-3.55). At a median (p25%-p75%) follow-up of 2.93 (1.93-3.72) years, we registered 0.28 deaths and 0.24 episodes of WHF per 1 person-year. Compared to baseline (urinary), CAPD led to increased sodium excretion (urinary plus dialyzed) since the first follow-up visit (p < 0.001). Over the follow-up, repeated measurements of total sodium removal were associated with a lower risk of death and episodes of WHF.

CONCLUSIONS

CAPD increased sodium removal in patients with refractory CHF. Elevated sodium removal identified those patients with a lower risk of death and episodes of WHF.

Research hotspots and emerging trends of automated peritoneal dialysis: A bibliometric analysis from 2000 to 2020

BACKGROUND

The implementation of automated peritoneal dialysis (APD) has considerably increased in many countries. We conducted a bibliometric analysis to evaluate the accumulating studies on APD in the last two decades quantitatively and qualitatively.

METHODS

Publications regarding APD research between 2000 and 2020 were retrieved from the Web of Science Core Collection database by using the index term "automated peritoneal dialysis." CiteSpace, VOSviewer, and an online platform were employed to analyze the number of publications and the collaboration relationships between countries, institutions, authors, and co-cited journals. Cluster analysis and burst keywords detection were performed on co-cited references and keywords, respectively.

RESULTS

We obtained a record of 545 publications related to APD in total. The United States was the country that contributes most, and Baxter Healthcare Corporation was the leading institution. Peritoneal Dialysis International was the most active journals in this field. Claudio Ranco was the most productive author, and Simon J Davies ranked the first in the cited authors. Co-cited reference cluster analysis and high frequency keywords showed that survival, ultrafiltration and peritonitis are continuous hot topics. While remote monitoring (RM) and telemedicine may be APD research frontiers according to burst keywords detection.

CONCLUSION

This bibliometric study provides comprehensive overview on the publications of APD over the past two decades. These findings help to identify the hotspots and explore new directions for future research. RM has become an emerging trend in APD field.

Understand the difference between clinical measured ultrafiltrationand real ultrafiltration in peritoneal dialysis

Background

It has been noticed for years that ultrafiltration (UF) is important for survival in peritoneal dialysis. On the other hand, precise and convenient UF measurement suitable for patient daily practice is not as straight forward as it is to measure UF in the lab. Both overfill and flush before fill used to be source of measurement error for clinical practice. However, controversy finding around UF in peritoneal dialysis still exists in some situation. The current study was to understand the difference between clinical measured UF and real UF. The effect of evaporation and specific gravity in clinical UF measurement were tested in the study.

Methods

Four different brands of dialysate were purchased from the market. The freshest dialysate available in the market were intentionally picked. The bags were all 2 L, 2.5% dextrose and traditional lactate buffered PD solution. They were stored in four different conditions with controlled temperature and humidity. The bags were weighted at baseline, 6 months and 12 months of storage. Specific gravity was measured in mixed 24 h drainage dialysate from 261 CAPD patients when they come for their routine solute clearance test.

Results

There was significant difference in dialysate bag weight at baseline between brands. The weight declined significantly after 12 month’s storage. The weight loss was greater in higher temperature and lower humidity. The dialysate in non-PVC package lose less weight than PVC package. The specific gravity of dialysate drainage was significantly higher than pure water and it was related to dialysate protein concentration.

Conclusion

Storage condition and duration, as well as the type of dialysate package have significant impact in dialysate bag weight before use. Evaporation is likely to be the reason behind. The fact that specific gravity of dialysate drainage is higher than 1 g/ml overestimates UF in manual exchanges, which contributes to systemic measurement error of ultrafiltration in CAPD.

Trial registration

ClinicalTrials.gov ID: NCT03864120 (March 8, 2019) (Understand the Difference Between Clinical Measured Ultrafiltration and Real Ultrafiltration).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02589-3.

Relationship between sodium removal, hydration and outcomes in peritoneal dialysis patients

BACKGROUND

Fluid overload (FO) in peritoneal dialysis (PD) patients is associated with mortality. We explore if low daily sodium removal is an independent risk factor for mortality. We examined severely FO PD patients established for >1 year in expectation that PD prescription would have been optimized for solute clearance and ultrafiltration. We also wish to determine the relationship between kt/v and sodium removal.

METHODS

Retrospective analysis of 231 PD patients with FO ≥2.0 L and compared with 218 PD patients who were euvolaemic throughout their PD treatment. Patients were followed up until death censored for transplantation.

RESULTS

Mean daily sodium removal in overhydrated patients was only 75 mmoles (=1.7 g). CAPD usage was more common in patients with the highest sodium removal. Achievement of UK guidelines for solute clearance and daily fluid removal were not independent predictors of mortality. Markers of sarcopenia (low serum albumin and high CRP) were associated with increased mortality, but these parameters were not independent predictors in a model that included functional assessment (Karnofsky score). Daily sodium removal was not predictive of mortality but the imprecision of clinically used sodium assay should be noted. The correlation between Na and kt/v is statistically significant but R² was weak at .07.

CONCLUSION

While diabetic males were more likely to become overhydrated, these factors did not increase mortality further. Traditional targets of 'dialysis adequacy' did not predict survival. Kt/v is not a good indicator of sodium removal which can be surprisingly low. Measuring sodium clearance may help clinicians optimize PD modality (CAPD vs. APD).

A comparative analysis of ambulatory BP profile and arterial stiffness between CAPD and APD

Prior studies have associated automated peritoneal dialysis (APD) with less effective volume and blood pressure (BP) control as compared with continuous ambulatory peritoneal dialysis (CAPD). Our study aimed to compare the volume status, ambulatory BP profile and severity of arterial stiffness between patients treated with CAPD versus APD. In a case-control design, 28 CAPD patients were matched in 1:1 ratio with 28 controls receiving APD for age, gender and diabetic status. Body composition was assessed with the method of bioimpendence spectroscopy. Twenty-four hours ambulatory BP monitoring with the Mobil-O-Graph device (IEM, Germany) was performed to determine peripheral and central hemodynamic parameters, heart rate-adjusted augmentation index (AIx75) and pulse wave velocity (PWV). Standardized office BP, antihypertensive medication use and extracellular-to-total body water ratio did not differ between CAPD and APD groups. Twenty-four hours brachial systolic BP (129.0 ± 17.3 vs. 128.1 ± 14.2 mmHg, P = 0.83) and 24-h aortic systolic BP (116.9 ± 16.4 vs. 116.4 ± 11.6 mmHg, P = 0.87) were similar in patients treated with CAPD versus APD. Similarly, there was no significant difference between PD modalities in severity of arterial stiffness, as assessed with 24-h AIx75 (24.8 ± 8.9 vs. 22.5 ± 9.1, P = 0.36) and 24-h PWV (9.1 ± 2.4 vs. 8.8 ± 2.1 m/s, P = 0.61). The present study suggests that there is no difference in peripheral and central hemodynamic parameters as well as in the severity of arterial stiffness between CAPD and APD. However, these observations should be interpreted within the context of clinical characteristics of patients included in this case-control study. The comparative effectiveness of these 2 PD modalities warrants further investigation in larger longitudinal studies.

Tissue sodium stores in peritoneal dialysis and hemodialysis patients determined by 23-sodium magnetic resonance imaging

BACKGROUND

Tissue sodium content in patients on maintenance hemodialysis (MHD) and peritoneal dialysis (PD) were previously explored using 23Sodium magnetic resonance imaging (23NaMRI). Larger studies would provide a better understanding of sodium stores in patients on dialysis as well as the factors influencing this sodium accumulation.

METHODS

In this cross-sectional study, we quantified the calf muscle and skin sodium content in 162 subjects (10 PD, 33 MHD patients, and 119 controls) using 23NaMRI. Plasma levels of interleukin-6 (IL-6) and high-sensitivity C-reactive protein (hsCRP) were measured to assess systemic inflammation. Sixty-four subjects had repeat 23NaMRI scans that were analyzed to assess the repeatability of the 23NaMRI measurements.

RESULTS

Patients on MHD and PD exhibited significantly higher muscle and skin sodium accumulation compared to controls. African American patients on dialysis exhibited greater muscle and skin sodium content compared to non-African Americans. Multivariable analysis showed that older age was associated with both higher muscle and skin sodium. Male sex was also associated with increased skin sodium deposition. Greater ultrafiltration was associated with lower skin sodium in patients on PD (Spearman's rho=-0.68, P = 0.035). Higher plasma IL-6 and hsCRP levels correlated with increased muscle and skin sodium content in the overall study population. Patients with higher baseline tissue sodium content exhibited greater variability in tissue sodium stores on repeat measurements.

CONCLUSIONS

Our findings highlight greater muscle and skin sodium content in dialysis patients compared to controls without kidney disease. Tissue sodium deposition and systemic inflammation seen in dialysis patients might influence one another bidirectionally.

Continuous Ambulatory Peritoneal Dialysis is Better than Automated Peritoneal Dialysis as First-Line Treatment in Renal Replacement Therapy

This article examines the roles of continuous ambulatory peritoneal dialysis (CAPD) versus automated peritoneal dialysis (APD) as first-line renal replacement therapy. To date, no high-quality large-scale randomized controlled studies have compared CAPD with APD as first-line therapy. However, a discussion on this issue is important so that nephrologists can decide and patients can have a choice of modality on which to start dialysis, especially in the context of health care economics. We review the literature and present Hong Kong as the model of a “CAPD first” policy, an appealing, cost-effective approach for any country.

An ideal renal replacement therapy should provide optimal survival, lowest possible risk for comorbidity, highest level of quality of life, and equally important, acceptable cost to society. When we consider this subject in the context that all patients should be started on one first-line modality, the data suggest that a “CAPD first” policy has all these advantages, with APD probably having the edge only with regard to patient preference. The present review highlights preservation of residual renal function, removal and balancing of sodium, incidence of peritonitis, peritoneal membrane transport status, patient rehabilitation, and financial issues in demonstrating that a “CAPD first” policy is the model that should be adopted.

Characterization of sodium removal to ultrafiltration volume in a peritoneal dialysis outpatient cohort

Background

Failure to control volume is the second most common cause of peritoneal dialysis (PD) technique failure. Sodium is primarily removed by convection, but according to the three-pore model, water and sodium movements are not necessarily concordant. We wished to determine factors increasing sodium to water clearance in clinical practice.

Methods

We reviewed 24-h peritoneal dialytic sodium removal (DSR) and ultrafiltration (UF) volume in consecutive PD patients attending for routine assessment of peritoneal membrane function and adequacy testing. We used a regression model with the DSR/UF ratio as the dependent variable. A second model with DSR as the dependent variable and interaction testing for UF was used as sensitivity analysis.

Results

We included 718 adult PD patients. Mean values were 51.8 ± 64.6 mmol/day and 512 ± 517 mL/day for DSR and UF, respectively. In multivariable analysis, DSR/UF ratio was positively associated with transport type (fast versus slow, P < 0.001), serum sodium (P < 0.001) and diabetes (P = 0.026), and negatively associated with PD mode [automated PD versus continuous ambulatory PD (CAPD), P < 0.001] and the use of 2.27% glucose dialysate (P < 0.001). Sensitivity analysis showed positive interaction with UF for transport type (P < 0.001) and serum sodium (P = 0.032) and negative interaction for PD mode (P < 0.001) and cycles number (P < 0.001).

Conclusions

CAPD, fast transport and high serum sodium allow relatively more sodium to be removed compared with water. Icodextrin has no effect on sodium removal once confounders have been accounted for. Although widely used in the assessment of PD patients, UF should not be considered as a surrogate for DSR in clinical practice.

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.

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.

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.

Use of Icodextrin during Nocturnal Automated Peritoneal Dialysis Allows Sustained Ultrafiltration While Reducing the Peritoneal Glucose Load: A Randomized Crossover Study

Background

Optimization of ultrafiltration and preservation of the peritoneal membrane are desirable objectives in peritoneal dialysis (PD) patients. Mixtures of glucose-and non-glucose-based solutions may help to meet both targets simultaneously.

Aim

To analyze the effects, in terms of ultrafiltration and peritoneal glucose load, of including icodextrin-based dialysate in the nocturnal schedule of patients undergoing automated PD (APD).

Method

Following a randomized crossover design, 17 APD patients underwent two 10-day study periods under identical prescription (including amino acid-based solution for the night schedule), except for the substitution of 2 L glucose-based dialysate in the nocturnal mixture (control) by a similar amount of icodextrin-based dialysate (icodextrin phase) in one period. Dependent variables included ultra-filtration, sodium removal, peritoneal glucose load, and residual renal function. We measured serum and urine levels of icodextrin metabolites at the end of each phase.

Results

Ultrafiltration was marginally higher during the icodextrin phase (median 815 vs 763 mL/day, p = 0.07), while peritoneal sodium removal was similar in both phases (74 vs 71 mmol/L/day). Peritoneal glucose load (median 67.5 vs 104.0 g/day, p < 0.005) and absorption (14.0 vs 35.6 g/day, p < 0.005) were lower during the icodextrin phase. Diuresis was also modestly lower during the icodextrin phase (500 vs 600 mL/day, p < 0.05). Serum levels of icodextrin metabolites were moderately higher in the icodextrin phase ( p < 0.005) in patients both on and off diurnal icodextrin.

Conclusion

Inclusion of amino acid- and icodextrin-based solutions in the nocturnal schedule of APD patients may allow sustained ultrafiltration and sodium removal while significantly reducing the peritoneal glucose load in these patients.

Sodium removal in peritoneal dialysis: is there room for a new parameter in dialysis adequacy?

In peritoneal dialysis (PD) (as well as in hemodialysis) small solute clearance measured as Kt/v urea has long been used as a surrogate of dialysis adequacy. A better urea clearance was initially thought to increase survival in dialysis patients (as shown in the CANUSA trial)(1), but  reanalysis of the data showed a superior contribution of residual renal function as a predictor of patient survival. Two randomized controlled trials (RCT)(2, 3)  supported this observation, demonstrating no survival benefit in patients with higher achieved Kt/v. Then guidelines were revised and a minimum Kt/v of 1,7/week was recommended but little emphasis was given to additional parameters of dialysis adequacy. As such, volume overload and sodium removal have gained major attention, since their optimization has been associated with decreased mortality in PD patients(4, 5). Inadequate sodium removal is associated with fluid overload which leads to ventricular hypertrophy and increased cardiovascular mortality(6). Individualized prescription is key for optimal sodium removal as there are differences between PD techniques (CAPD versus APD) and new strategies for sodium removal have emerged (low sodium solutions and adapted PD). In conclusion, future guidelines should address parameters associated with increased survival outcomes (sodium removal playing an important role) and abandon the current one fit all prescription model.

Defining the role of peritoneal dialysis in management of congestive heart failure

Introduction: Congestion is an integral component of heart failure (HF) pathophysiology and portends an adverse impact on outcome. Peritoneal dialysis (PD) is a home-based therapeutic modality that has been used in the setting of refractory congestive HF to help optimize volume status. Not only does PD allow for customized sodium and water removal, but it also provides the opportunity for the patients to fully benefit from guideline-directed medical therapy for HF that could have otherwise been challenging to use. Areas covered: Authors provide an overview of the pathophysiologic basis for the use of PD in HF, followed by a review of the findings of the main clinical trials such as the salutary impact on HF re-admissions and quality of life. Since the goals of therapy in this setting differ from those for patients with end-stage renal disease, pertinent practical considerations in the use of this modality are then discussed as well as potential barriers. Expert opinion: For patients with chronic refractory HF, PD represents an alternative to medical therapy alone. Identification of patients that would benefit most from this modality and detection of major enablers and obstacles for the implementation of this therapy should be the focus of future studies.

Hyponatremia in the Dialysis Population

Sodium derangements are among the most frequently encountered electrolyte disorders in patients with end-stage renal disease. As dialysis patients are predisposed to hyponatremia via multiple pathways, assessment of extracellular volume status is an essential first step in disentangling potential etiologic factors. In addition, multiple large population-based studies indicate that proxies of malnutrition (e.g., low body mass index, serum albumin, and serum creatinine levels) and loss of residual kidney function are important determinants of hyponatremia in dialysis patients. Among hemodialysis and peritoneal dialysis patients, evidence suggests that incrementally lower sodium levels are associated with increasingly higher death risk, highlighting the long-term risk of hyponatremia. Whereas in conventional survival models incrementally lower serum sodium concentrations are associated with worse mortality in hemodialysis patients, studies that have examined repeated measures of predialysis sodium have demonstrated mixed associations of time-varying sodium with higher mortality risk (i.e., U-shaped vs. inverse linear relationships). Although the causality of the hyponatremia-mortality association in dialysis patients remains uncertain, there are several plausible pathways by which lower sodium levels may lead to higher death risk, including central nervous system toxicity, falls and fractures, infection-related complications, and impaired cardiac function. Areas of uncertainty ripe for future studies include the following: (i) mechanistic pathways by which lower serum sodium levels are linked with higher mortality in dialysis patients, (ii) whether correction of sodium derangements improves outcomes, (iii) the optimal sodium target, and (iv) the impact of age and other sociodemographic factors on hyponatremia-outcome associations.

Effectiveness and Safety of Peritoneal Dialysis Treatment in Patients with Refractory Congestive Heart Failure due to Chronic Cardiorenal Syndrome

Aims

To evaluate the effectiveness and safety of peritoneal dialysis (PD) in treating refractory congestive heart failure (RCHF) with cardiorenal syndrome (CRS).

Methods

A total of 36 patients with RCHF were divided into type 2 CRS group (group A) and non-type 2 CRS group (group B) according to the patients' clinical presentations and the ratio of serum urea to creatinine and urinary analyses in this prospective study. All patients were followed up till death or discontinuation of PD. Data were collected for analysis, including patient survival time on PD, technique failure, changes of heart function, and complications associated with PD treatment and hospitalization.

Results

There were 27 deaths and 9 patients quitting PD program after a follow-up for 73 months with an average PD time of 22.8 ± 18.2 months. A significant longer PD time was found in group B as compared with that in group A (29.0 ± 19.4 versus 13.1 ± 10.6 months, p = 0.003). Kaplan–Meier curves showed a higher survival probability in group B than that in group A (p < 0.001). Multivariate regression demonstrated that type 2 CRS was an independent risk factor for short survival time on PD. The benefit of PD on the improvement of survival and LVEF was limited to group B patients, but absent from group A patients. The impairment of exercise tolerance indicated by NYHA classification was markedly improved by PD for both groups. The technique survival was high, and the hospital readmission was evidently decreased for both group A and group B patients.

Conclusions

Our data suggest that PD is a safe and feasible palliative treatment for RCHF with type 2 CRS, though the long-term survival could not be expected for patients with the type 2 CRS. Registration ID Number is ChiCTR1800015910.

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.

Left ventricular hypertrophy and blood pressure control in automated and continuous ambulatory peritoneal dialysis patients

Hypertension, non-dipper blood pressure (BP) pattern and decrease in daily urine output have been associated with left ventricular hypertrophy (LVH) in peritoneal dialysis (PD) patients. However, there is lack of data regarding the impact of different PD regimens on these factors. We aimed to investigate the impact of circadian rhythm of BP on LVH in end-stage renal disease patients using automated peritoneal dialysis (APD) or continuous ambulatory peritoneal dialysis (CAPD) modalities. Twenty APD (7 men, 13 women) and 28 CAPD (16 men, 12 women) patients were included into the study. 24-h ambulatory blood pressure monitoring (ABPM) and transthoracic echocardiography besides routine blood examinations were performed. Two groups were compared with each other for ABPM measurements, BP loads, dipping patterns, left ventricular mass index (LVMI) and daily urine output. Mean systolic and diastolic BP measurements, BP loads, LVMI, residual renal function (RRF) and percentage of non-dippers were found to be similar for the two groups. There were positive correlations of LVMI with BP measurements and BP loads. LVMI was found to be significantly higher in diastolic non-dippers compared to dippers (140.4 ± 35.3 vs 114.5 ± 29.7, respectively, P = 0.02). RRF and BP were found to be independent predictors of LVMI. Non-dipping BP pattern was a frequent finding among all PD patients without an inter-group difference. Additionally, higher BP measurements, decrease in daily urine output and non-dipper diastolic BP pattern were associated with LVMI. In order to avoid LVH, besides correction of anemia and volume control, circadian BP variability and diastolic dipping should also be taken into consideration in PD patients.

Automated peritoneal dialysis prescriptions for enhancing sodium and fluid removal: a predictive analysis of optimized, patient-specific dwell times for the day period

BACKGROUND

Remaining edema-free is a challenge for many automated peritoneal dialysis (APD) patients, especially those with fast ("high") transport characteristics. Although increased use of peritoneal dialysis (PD) solutions with high glucose concentrations may improve volume control, frequent use of such solutions is undesirable.

METHODS

We used the 3-pore kinetic model to evaluate 4 alternative therapy prescriptions for the APD day exchange in anuric patients with high, high-average, and low-average transport characteristics. Four prescriptions were modeled: Therapy 1: Optimal, individualized dwell times with a dry period. Therapy 2: Use of a midday exchange. Therapy 3: Use of an icodextrin-containing dialysate during a 14-hour dwell. Therapy 4: Use of optimal, individualized dwell times, followed by an icodextrin dwell to complete the daytime period. The alternative therapies were compared with a reference standard therapy using glucose solution during a 14-hour dwell. The nighttime prescription was identical in all cases (10 L over 10 hours), and all glucose solutions contained 2.27% glucose. Net ultrafiltration (UF), sodium removal (NaR), total carbohydrate (CHO) absorption, and weekly urea Kt/V for a 24-hour period were computed and compared.

RESULTS

The UF and NaR were substantially higher with therapy 1 than with standard therapy (1034 mL vs 621 mL and 96 mmol vs 51 mmol respectively), without significant changes in CHO absorption or urea Kt/V. However, therapy 1 resulted in reduced β2-microglobulin clearance (0.74 mL/min vs 0.89 mL/min with standard therapy). Compared with therapy 1, therapy 2 improved UF and NaR (1062 mL vs 1034 mL and 99 mmol vs 96 mmol); however, that improvement is likely not clinically significant. Therapy 2 also resulted in a higher Kt/V (2.07 vs 1.72), but at the expense of higher glucose absorption (difference: 42 g). The UF and NaR were highest with a long icodextrin-containing daytime dwell either preceded by a short optimized dwell (1426 mL and 155 mmol) or without such a dwell (1327 mL and 148 mmol).

CONCLUSIONS

The 3-pore model predictions revealed that patient-specific optimal dwell times and regimens with a longer day dwell might provide improved UF and NaR options in APD patients with a variety of peritoneal membrane transport characteristics. In patients without access to icodextrin, therapy 1 might enhance UF and NaR and provide a short-term option to increase fluid removal. Although that approach may offer clinicians a therapeutic option for the overhydrated patient who requires increased UF in the short term, APD prescriptions including icodextrin provide a means to augment sodium and fluid removal. Data from clinical trials are needed to confirm the predictions from this study.

Icodextrin Simplifies PD Therapy by Equalizing UF and Sodium Removal Among Patient Transport Types During Long Dwells: A Modeling Study

♦

BACKGROUND

In recent years, results from clinical studies have changed the focus of peritoneal dialysis (PD) adequacy from small solute clearance to volume control, resulting in continued efforts to improve fluid and sodium removal in PD patients. We used a modified 3-pore model to theoretically predict fluid and solute removal using glucose-based and icodextrin solutions for a wide range of transport characteristics with automated PD (APD) and continuous ambulatory PD (CAPD) therapies. ♦

METHODS

Simulations were performed for the day (APD: 15-hr, 2.27% glucose and 7.5% icodextrin; CAPD: 3x5-hr, 1.36% and 2.27% glucose) and night (APD: 9-hr, 1.36% glucose; CAPD: 9-hr, 2.27% glucose and 7.5% icodextrin) dialysis periods separately. During APD, the number of night exchanges (N) was varied from 3 to 7. Ultrafiltration (UF), sodium removal (NaR), total carbohydrate absorption (CHO), UF efficiency (UFE), and sodium removal efficiency (NaRE) were calculated. Typical patients in fast (i.e. high, H), average (high-average, HA; low-average, LA), and slow (low, L) transport groups with no residual kidney function were considered. ♦

RESULTS

The effective dwell times varied between 1.0 and 14.7 hours depending on the number of exchanges. With glucose-based solutions, differences in UF and NaR between H and L transport patients ranged from 140 mL and 2 mmol (APD night, n = 7) to 778 mL and 56.4 mmol (CAPD day, 2.27%). With icodextrin, differences in UF and NaR ranged from 1 mL and 1.1 mmol (CAPD night) to 59 mL and 6.1 mmol (APD day). The use of icodextrin resulted in greater CHO than 2.27% glucose (APD: 27.1 - 35.6 g more; CAPD: 17.1 - 17.5 g more). The UFE and NaRE were greater for all patients with icodextrin than with glucose-based solution in both therapy modalities, except for slow transport patients in CAPD. ♦

CONCLUSION

This modeling study shows that the dependence of UF and NaR on patient transport type observed with glucose-based solutions can be minimized using icodextrin during the long dwells of APD and CAPD. While this approach simplifies the PD prescription by minimizing the dependencies of ultrafiltration and sodium removal on patient transport type when using icodextrin, it improves fluid and sodium removal efficiencies in fast and average transport patients without any added glucose exposure.

Removal of Different Classes of Uremic Toxins in APD vs CAPD: A Randomized Cross-Over Study

♦

AIM

In this study, we investigated, and this for the different classes of uremic toxins, whether increasing dialysate volume by shifting from continuous ambulatory peritoneal dialysis (CAPD) to higher volume automated peritoneal dialysis (APD) increases total solute clearance. ♦

METHODS

Patients on peritoneal dialysis were randomized in a cross-over design to one 24-hour session of first a CAPD regimen (3*2 L of Physioneal 1.36% and 1*2 L of icodextrin) or APD (consisting of 5 cycles of 2 L Physioneal 1.36 and 1 cycle of 2 L Extraneal), and the other week the alternate regime, each patient serving as his/her own control. Dialysate, blood and urine samples were collected and frozen for later batch analysis of concentrations of urea, creatinine, phosphorus, uric acid, hippuric acid, 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid, indoxyl sulfate, indole acetic acid, and p-cresyl sulfate. For the protein-bound solutes, total and free fractions were determined. Total, peritoneal and renal clearance (K) and mass removal (MR) of each solute were calculated, using validated models. ♦

RESULTS

In 15 patients (11 male, 3 diabetics, 56 ± 16 years, 8 on CAPD, time on peritoneal dialysis 12 ± 14 months, and residual renal function of 9.9 ± 5.4 mL/min) dialysate over plasma ratio for creatinine (D/Pcrea) was 0.62 ± 0.10. Drained volume and obtained ultrafiltration were higher with APD vs CAPD (13.3 ± 0.5 L vs 8.5 ± 0.7 L and 1.3 ± 0.5 L vs 0.5 ± 0.7 L), whereas urine output was lower (1.0 ± 0.5 L vs 1.4 ± 0.6 L). Total clearance and MR tended to be higher for CAPD vs APD for all small and water soluble solutes, but mainly because of higher renal contribution, with no difference in the peritoneal contribution. For the protein-bound solutes, no differences in clearance or mass removal were observed. ♦

CONCLUSION

Although the drained dialysate volume nearly doubled, APD did not result in better peritoneal clearance or solute removal vs classic CAPD. APD resulted in better ultrafiltration, but at the expense of residual urinary output and clearance.

Approach to the Metabolic Implications of Peritoneal Dialysis in Acute Kidney Injury

During the 1970s and 1980s, peritoneal dialysis (PD) was widely accepted as the standard treatment for acute kidney injury (AKI). However, advances in the techniques of extracorporeal blood purification gradually reduced its use, making PD an underused modality in this context. Although PD for AKI is an underutilized modality worldwide, it is frequently used in developing countries because of its lower cost and minimal infrastructure requirements. Recent studies have shown that PD administered continuously through a flexible catheter and cycler is an effective treatment in AKI because it ensures adequate fluid status and metabolic control. However, the use of PD in AKI has several limitations, such as the need for an intact peritoneal cavity and, in emergency situations such as severe fluid overload and severe hyperkalemia, an efficacy that is lower than that with extracorporeal blood purification techniques. Metabolic, infectious, and mechanical disorders related to PD are also limitations.Among the metabolic complications of PD are hyperglycemia, hypernatremia, protein loss into the dialysate, and hypercatabolism. Hyperglycemia is caused by the use of dialysate containing high concentrations of glucose. Hypernatremia is a result of short dialysate dwell times during the rapid exchanges of high-volume PD. Protein loss into the dialysate can reach 48 g daily, worsening the nutrition status of patients already depleted by AKI. Severe hypercatabolism caused by PD remains controversial and occurs because PD methods cannot provide an adequate dialysis dose for AKI patients.Few studies have assessed the metabolic implications of PD in AKI patients. Evaluation of these implications is relatively simple, imposes no additional costs, and can provide information about the severity of the disease. Evaluation could also guide the selection of therapeutic, dialytic, and nutrition measures, preventing metabolic complications. The present manuscript describes the metabolic implications of PD and reviews the literature on how to prevent metabolic complications.

Comparative outcomes between continuous ambulatory and automated peritoneal dialysis: a narrative review

Automated methods for delivering peritoneal dialysis (PD) to persons with end-stage renal disease continue to gain popularity worldwide, particularly in developed countries. However, the endeavor to automate the PD process has not been advanced on the strength of high-level evidence for superiority of automated over manual methods. This article summarizes available studies that have shed light on the evidence that compares the association of treatment with continuous ambulatory PD or automated PD (APD) with clinically meaningful outcomes. Published evidence, primarily from observational studies, has been unable to demonstrate a consistent difference in residual kidney function loss rate, peritonitis rate, maintenance of euvolemia, technique survival, mortality, or health-related quality of life in individuals undergoing continuous ambulatory PD versus APD. At the same time, the future of APD technology appears ripe for further improvement, such as the incorporation of voice commands and expanded use of telemedicine. Given these considerations, it appears that patient choice should drive the decision about PD modality.

Hyponatremia in peritoneal dialysis: epidemiology in a single center and correlation with clinical and biochemical parameters

BACKGROUND

Hyponatremia in peritoneal dialysis (PD) patients has previously been associated with water overload and weight gain, or with malnutrition and intracellular potassium depletion. Although there is a sizable literature about transmembrane sodium and water removal in PD, there are few reports about the incidence and characteristics of hyponatremia in the clinical setting.

AIM

We evaluated the incidence and factors associated with hyponatremia in PD patients in a single PD unit.

METHODS

We retrospectively evaluated the records of all patients (n = 198) who were treated with PD in the Home PD Unit of the University Health Network at Toronto General Hospital during 2010. We identified 166 patients who had a minimum follow-up of 60 days during 2010 and at least 2 consecutive sodium measurements at least a month apart. We examined baseline differences between patients who developed hyponatremia and those who did not, and clinical and biochemical factors that correlated with mean sodium values. In the 24 patients who developed hyponatremia, we examined paired differences between the normonatremic and hyponatremic periods. Finally, we investigated any possible correlations of change in serum sodium with clinical and biochemical characteristics before and during the hyponatremic period.

RESULTS

The incidence of hyponatremia was 14.5%. In multivariate analysis, serum sodium correlated significantly and independently with residual renal function (RRF: r = 0.463, p = 0.0001) and negatively with the daily volume of instilled icodextrin (r = -0.476, p = 0.0001). Residual renal function was significantly lower in patients with hyponatremia than in those with normal serum sodium (1.97 ± 2.3 mL/min vs 4.31 ± 5.01 mL/min, p = 0.033). The mean paired difference in body weight was -1.113 kg and the median difference was -0.55 kg (range: -8.5 kg to +4.2 kg). Impressively, hyponatremia was not associated with an increase in body weight in most patients who developed this complication (13 of 16 for whom comparative weights were known). Moreover, the mean paired change in serum sodium (ΔNa) from normonatremia to hyponatremia was, contrary to our expectations, significantly correlated with a decrease in body weight (r = 0.584, p = 0.017). The ΔNa was also significantly correlated with serum potassium (r = 0.526, p = 0.008), the greatest drop in serum sodium being associated with lower serum potassium in the hyponatremic period, as predicted.

CONCLUSIONS

Hyponatremia is seen more often than expected in a clinical setting. Serum sodium is strongly correlated with RRF, hyponatremia being associated with lower RRF. In patients who experienced hyponatremia, the fall in serum sodium was associated with a decrease, not an increase, in body weight and was correlated with serum potassium, suggesting that sodium and potassium depletion-and, by inference, malnutrition-may be important contributors in the clinical setting.

[Peritoneal dialysis from the beginnings up to today: which developments of the last decades were important?]

During the past years new developments in peritoneal dialysis (PD) technique have resulted in continuous improvement of patient outcome. The importance of salt and fluid balance, residual renal function and peritoneal glucose load are of increasing interest, whereas small solute clearances have lost importance. In patients with high peritoneal transport rates automated PD (APD) is indicated. However, APD can also be chosen as initial PD treatment since recent studies show comparable or even better survival as compared to continuous ambulatory PD patients. Alternative PD solutions improve peritoneal ultrafiltration (icodextrin), reduce peritoneal glucose load (amino acid solution, icodextrin) and protect the peritoneal membrane (solutions with low concentration of glucose degradation products). Infection risk can be reduced when using antibiotic creams, but resistances should be considered. Ongoing studies will clarify if non-antibiotic agents, e.g. medihoney, are effective in preventing PD-associated infections. Due to these improvements PD and hemodialysis have become equivalent treatments.

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.

Endothelin-1 acutely reduces the permeability of visceral sheep peritoneum in vitro through both endothelin-A and endothelin-B receptors

Mesothelium is an important part of the peritoneal barrier for water and ion transport, essential for effective peritoneal dialysis (PD). Peritoneal fibrosis has been associated with PD treatment failure. Endothelin-1 (ET-1) is a potent vasoactive peptide, involved in pathologic fibrotic processes. Its action is mediated mainly by endothelin type A (ETA ) and type B (ETB ) receptors. The aim of this study was to investigate, by Ussing chamber experiments, the effect of ET-1 on the transmesothelial electrical resistance (RTM ) of the isolated visceral sheep peritoneum. Intact sheets of visceral peritoneum were obtained from 40 adult sheep and mounted in Ussing-type chambers. ET-1 (10(-7)  M), BQ-123 (ETA receptor antagonist; 10(-6)  M), BQ-788 (ETB receptor antagonist; 10(-6)  M), and their combinations were added on the apical and the basolateral side of the peritoneum. RTM was measured before and serially after addition of the substances, and changes were registered as percentage (ΔRTM %). RTM increased within 1 min after addition of ET-1 apically (ΔRTM 65.03 ± 15.87%; P < 0.05) or basolaterally (ΔRTM 85.5 ± 20.86%; P < 0.05). BQ-123 and BQ-788 and their combination significantly reduced (P < 0.05) the effect of ET-1 to a similar degree in all cases. These results clearly indicate that ET-1 reduces ionic permeability of the visceral sheep peritoneum in vitro. Additionally, it is obvious that this inhibitory effect is mediated through both ETA and ETB receptors.

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.

Fluid state and blood pressure control: no differences between APD and CAPD

The aim of this study was to compare fluid state, ambulatory blood pressure, and sodium removal in automated peritoneal dialysis (APD) and continuous ambulatory peritoneal dialysis (CAPD). This observational, cross-sectional study comprised 20 APD and 24 CAPD patients with a mean duration on peritoneal dialysis of 30 ± 26 and 21 ± 23 months, respectively. Sixty-four percent of the patients were treated with icodextrin. The methods used were 24 hr dialysate and urine collections, standardized 3.86% glucose peritoneal equilibration test (PET), bioimpedance analysis, and 24 hr ambulatory blood pressure monitoring. Extracellular water (ECW) corrected for body weight was 0.23 6 0.03 L/kg both in APD and CAPD patients. The slope normovolemia value according to Chamney was 0.0 6 0.2 L/kg in APD patients and 0.0 6 0.05 L/kg in CAPD patients (not significant [NS]). Mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) were respectively, 132 ± 25 and 79 ± 8 mm Hg in APD and 129 ± 16 and 76 ± 11 mm Hg in CAPD patients (NS). Sodium concentration in dialysate was respectively, 129.5 ± 3.5 mmol/L in APD and 132.4 ± 4.1 mmol/L in CAPD (p= 0.017). Dialysate sodium removal was 80.6 ± 78.4 mmol/24 hr in APD and 108.7 ± 96.8 mmol/24 hr in CAPD patients (NS). Natriuresis was respectively, in APD 76.6 ± 65.5 mmol/24 hr and in CAPD 93.5 ± 61.7 mmol/24 hr (NS). Total sodium removal was 149.5 ± 76.6 mmol/24 hr in APD and 198.4 ± 75.0 mmol/24 hr in CAPD (p= .039). Despite a higher daily sodium removal in CAPD patients, fluid state and blood pressure were not different between APD and CAPD. In general, volume status and blood pressure appeared to be reasonably controlled in this unselected population.

Comparison of Outcomes on Continuous Ambulatory Peritoneal Dialysis versus Automated Peritoneal Dialysis: Results from a USA Database

Background and Objective

Automated peritoneal dialysis (APD) is being increasingly used as an alternative to continuous ambulatory peritoneal dialysis (CAPD). However, there has been concern regarding reduced sodium removal leading to hypertension and resulting in a faster decline in residual renal function (RRF). The objective of the present study was to compare patient and technique survival and other relevant parameters between patients treated with APD and patients treated with CAPD.

Methods

Data for incident patients were retrieved from the database of the Renal Research Institute, New York. Treatment modality was defined 90 days after the start of dialysis treatment. In addition to technique and patient survival, RRF, blood pressure, and laboratory parameters were also compared.

Results

179 CAPD and 441 APD patients were studied. Mean as-treated survival was 1407 days [95% confidence interval (CI) 1211 - 1601] in CAPD patients and 1616 days (95% CI 1478 - 1764) in APD patients. Adjusted hazard ratio (HR) for mortality was 1.31 in CAPD compared to APD (95% CI 0.76 - 2.25, p = NS). Unadjusted as-treated technique survival was lower in CAPD compared to APD, with HR 2.84 (95% CI 1.65 - 4.88, p = 0.002); adjusted HR was 1.81 (95% CI 0.94 - 3.57, p = 0.08). Peritonitis rate was 0.3 episodes/ patient-year for CAPD and APD; exit-site/tunnel infection rate was 0.1 and 0.3 episodes/patient-year for CAPD and APD respectively (p = NS).

Conclusions

Patient survival was not significantly different between APD and CAPD patients, whereas technique survival appeared to be higher in APD patients and could not be explained by differences in infectious complications. No difference in blood pressure control or decline in RRF was observed between the 2 modalities. Based on these results, APD appears to be an acceptable alternative to CAPD, although technique prescription should always follow individual judgment.

Comparison of Blood Pressure Control and Left Ventricular Hypertrophy in Patients on Continuous Ambulatory Peritoneal Dialysis (CAPD) and Automated Peritoneal Dialysis (APD)

This study aimed to investigate the influence of different peritoneal dialysis regimens on blood pressure control, the diurnal pattern of blood pressure and left ventricular hypertrophy in patients on peritoneal dialysis. Forty-four patients undergoing peritoneal dialysis were enrolled into the study. Patients were treated with different regimens of peritoneal dialysis: 26 patients on continuous ambulatory peritoneal dialysis (CAPD) and 18 patients on automated peritoneal dialysis (APD). All patients performed 24-hour ambulatory blood pressure monitoring (ABPM) and echocardiography. Echocardiography was performed for measurement of cardiac parameters and calculation of left ventricular mass index (LVMI). There were no significant differences in average of systolic and diastolic blood pressure during 24-hour, daytime, and nighttime between CAPD and APD groups. There were no significant differences in diurnal variation of blood pressure, systolic and diastolic blood pressure load, and LVMI between CAPD and APD groups. LVMI was associated with 24 hour systolic blood pressure load (r = 0.311, P < 0.05) and daytime systolic blood pressure load (r = 0.360, P < 0.05). In conclusion, this study found that there is no difference in blood pressure control, diurnal variation of blood pressure and left ventricular hypertrophy between CAPD and APD patients. The different peritoneal dialysis regimens might not influence blood pressure control and diurnal variation of blood pressure in patients on peritoneal dialysis.

Three-pore model predictions of 24-hour automated peritoneal dialysis therapy using bimodal solutions

BACKGROUND

Recently, bimodal peritoneal dialysis (PD) solutions containing low concentrations of Na have been shown to increase 24-hour ultrafiltration (UF) or UF efficiency (UF volume per gram of carbohydrate or CHO absorbed) and Na removal in high ("fast") transport patients during automated PD therapy. We used computer simulations to compare UF efficiency and Na removal at equivalent 24-hour UF volumes using either a generic bimodal solution (2.27% glucose + 7.5% icodextrin) during the long dwell or an increase in the glucose concentration during the short dwells, with all solutions containing Na at the conventional concentration (132 mEq/L).

METHODS

The 3-pore model has been shown to accurately predict peritoneal transport for PD solutions containing glucose or icodextrin, or both. Here, we used that model to calculate 24-hour UF volume, CHO absorption, and Na removal for high (H), high-average (HA), and low-average (LA) transport patients on automated PD. Nighttime therapy consisted of 1.36% or 2.27% glucose solution (or both), and daytime therapy consisted of either Extraneal (Baxter Healthcare Corporation, Deerfield, IL, USA) or a bimodal solution.

RESULTS

As expected, addition of glucose to either the long dwell or the short dwells resulted in increased UF volume and glucose absorption. The increase in UF was a function of patient transport type (bimodal range: 288 - 490 mL; short-dwell range: 323 - 350 mL), and the increase in CHO absorption was smaller with glucose added to short dwells than with bimodal solution (range: 18 - 30 g vs. 34 - 39 g). The 24-hour UF efficiency was higher when high glucose concentrations were used during short-dwell exchanges than when a bimodal PD solution was used for the long dwell (0.6 to 1.2 mL/g vs. -0.1 to 0.5 mL/g). By contrast, Na removal was lower with the short-dwell exchanges (28.3 - 30.7 mmol vs. 36.2 - 53.3 mmol), likely because of more pronounced Na sieving.

CONCLUSIONS

Our modeling studies predict that generic bimodal PD solutions will provide higher Na removal but not higher 24-hour UF efficiency compared with current automated PD prescriptions using Extraneal for the long dwell and glucose-containing solutions for the short dwells. The modeling predictions from this study require clinical validation.

Fluid status in peritoneal dialysis patients: the European Body Composition Monitoring (EuroBCM) study cohort

BACKGROUND

Euvolemia is an important adequacy parameter in peritoneal dialysis (PD) patients. However, accurate tools to evaluate volume status in clinical practice and data on volume status in PD patients as compared to healthy population, and the associated factors, have not been available so far.

METHODS

We used a bio-impedance spectroscopy device, the Body Composition Monitor (BCM) to assess volume status in a cross-sectional cohort of prevalent PD patients in different European countries. The results were compared to an age and gender matched healthy population.

RESULTS

Only 40% out of 639 patients from 28 centres in 6 countries were normovolemic. Severe fluid overload was present in 25.2%. There was a wide scatter in the relation between blood pressure and volume status. In a multivariate analysis in the subgroup of patients from countries with unrestricted availability of all PD modalities and fluid types, older age, male gender, lower serum albumin, lower BMI, diabetes, higher systolic blood pressure, and use of at least one exchange per day with the highest hypertonic glucose were associated with higher relative tissue hydration. Neither urinary output nor ultrafiltration, PD fluid type or PD modality were retained in the model (total R² of the model = 0.57).

CONCLUSIONS

The EuroBCM study demonstrates some interesting issues regarding volume status in PD. As in HD patients, hypervolemia is a frequent condition in PD patients and blood pressure can be a misleading clinical tool to evaluate volume status. To monitor fluid balance, not only fluid output but also dietary input should be considered. Close monitoring of volume status, a correct dialysis prescription adapted to the needs of the patient and dietary measures seem to be warranted to avoid hypervolemia.

Protective measures against ultrafiltration failure in peritoneal dialysis patients

Ultrafiltration failure in patients undergoing peritoneal dialysis is a condition with an incidence that increases over time. It is related to increased cardiovascular morbidity and mortality and is a major cause of the abandonment of the treatment technique. Because the number of patients undergoing renal replacement therapy is increasing with society aging and because approximately 10% of this population is treated with peritoneal dialysis, this matter is becoming more common in everyday practice for clinicians involved in the care of patients with chronic renal failure. In this review, we summarize the available measures used to prevent and treat ultrafiltration failure and the current state of research in the field, both in the experimental and clinical settings, focusing on the possible clinical applications of recent findings.

Cardiac Function and Structure in Longitudinal Analysis of Echocardiography in Peritoneal Dialysis Patients

♦ Background

Echocardiography is widely used for the evaluation of cardiac structures and function. The prognostic value of assessment of left cardiac atrium (LA) size in peritoneal dialysis (PD) patients is still unclear. The objective of the present study is to investigate prospectively a longitudinal monitoring of echocardiography parameters after start of PD. We also investigated a correlation study among plasma atrial natriuretic peptide (ANP) level, LA size, and cardiac function undergoing aggressive treatment.

♦ Methods

Correlation among plasma ANP, LA size, and cardiac function was prospectively analyzed by Doppler echocardiography in 32 PD patients in Juntendo University Hospital, Tokyo. Measurement of these parameters was performed at 0, 6, 12, 18, and 24 months after start of PD. All patients were treated with an angiotensin type 1 receptor blocker to control blood pressure to less than 140/90 mmHg. Other antihypertensive drugs such as diuretics and/or calcium channel blockers were added if blood pressure rose to over 140/90 mmHg. Hemoglobin and hematocrit levels were targeted at 10.0 g/dL and 30.0% respectively with recombinant human erythropoietin treatment. A diuretic was added or patients decreased their water intake if ANP was more than 43.0 pg/mL or LA diameter (LAD) more than 39 mm, and for other basic markers of volume status. Cardiac function was measured before and after drainage of PD fluid to evaluate the influence of cardiac function.

♦ Results

LAD at start of dialysis (36 ± 4.6 mm) decreased significantly to 33 ± 3.3 mm ( p < 0.05), 33 ± 3.2 mm ( p < 0.05), and 33 ± 3.6 mm ( p < 0.05) after 6, 12, and 24 months, respectively. Ejection fraction after 6 months was significantly increased compared with that at start of dialysis ( p < 0.05). Left ventricular mass index (LVMI) after 6, 12, and 24 months was significantly decreased compared with that at start of dialysis ( p < 0.05). ANP was 56 ± 39 pg/mL at start of dialysis and decreased significantly to 33 ± 19 pg/mL after 24 months ( p < 0.05). ANP was significantly correlated with LAD ( r = 0.412, p < 0.01), transmitral A wave flow velocity ( r = 0.429, p < 0.01), and LVMI ( r = 0.426, p < 0.01). Instillation of the dialysis fluid did not affect any parameters except inferior vena cava dimension.

♦ Conclusions

This study demonstrates a reduction in LA size and LVMI in PD patients followed over 24 months. Left ventricular structure, contraction, and compliance were well preserved in PD patients undergoing aggressive treatment based on measurements of plasma ANP and LAD.

Comparison of fluid status in patients treated by different modalities of peritoneal dialysis using multi-frequency bioimpedance

BACKGROUND AND AIMS

Patients treated by peritoneal dialysis, especially those using automatic cyclers, are frequently found to be hypervolemic. To determine whether there are significant differences between the currently available modalities of peritoneal dialysis, we analyzed whether differences in transporter status and treatment modality had a discernible effect on extracellular fluid volumes as measured by multi-frequency bioimpedance.

METHODS

Two hundred prevalent peritoneal dialysis patients, 48% male, mean age 54.9 yr (SD+/-15.6), were studied using multi-frequency bioimpedance following a standard peritoneal equilibration test; 63 patients were treated by CAPD, 29 by APD, 96 by CCPD and 12 by OCCPD.

RESULTS

There were no differences in extracellular volumes, or extracellular volume adjusted for height, or as a ratio to total body water between the groups. As expected, extracellular volume adjusted for height depended upon bodyweight (r=0.412, p<0.001), sex (r=0.457, p<0.001) and systolic blood pressure (r=0.162, p=0.023), and extracellular volume to total body water related to the reciprocal of total daily peritoneal ultrafiltration losses (r=-0.0254, p=0.003) and urine output (-0.254, p=0.003). More importantly, on logistical regression analysis the ratio of extracellular fluid to total body fluid increased with falling albumin, F=21.5 p<0.001, increasing age, F=18.5 p<0.001, urine output F=6.46, p=0.014, total daily ultrafiltration, F=3.52 and protein intake p=0.003. Extracellular fluid adjusted for total body fluid was associated with CRP (males F=6.03, p=0.03, females F=4.438, p=0.04).

CONCLUSION

Patients were more likely to have an expanded extracellular fluid volume if they had reduced daily fluid losses, but also with biomarkers typically associated with poor nutrition and inflammation.

Body composition, hydration, and related parameters in hemodialysis versus peritoneal dialysis patients

AIMS

Maintaining euvolemia is an important goal in patients on renal replacement therapy. However, adequate assessment of volume status in clinical practice is hampered by a lack of accurate measuring tools. A new multifrequency bioimpedance tool has recently been validated. This study compares volume status in peritoneal dialysis (PD) and hemodialysis (HD) patients in a single center.

METHODS

Body Composition Monitoring (BCM; Fresenius Medical Care, Bad Homburg, Germany) was performed in all patients on PD or HD without contraindication. PD patients were measured with a full abdomen; HD patients were measured at the midweek session, once immediately before and once 20 minutes after dialysis. Clinical overhydration was defined as an overhydration-to-extracellular water ratio of >0.15.

RESULTS

Total body water, extracellular water, and intracellular water were 33.7 +/- 6.9 L versus 31.8 +/- 8.1 L vs 33.9 +/- 6.7 L, 16.4 +/- 3.9 L vs 15.3 +/- 4.9 L vs 16.8 +/- 3.3 L, and 17.1 +/- 6.2 L vs 16.5 +/- 4.6 L vs 17.2 +/- 3.9 L in the pre-HD, post-HD, and PD patients, respectively (p = NS). In the pre-HD and the PD patients, overhydration was 1.9 +/- 1.7 L and 2.1 +/- 2.3 L, whereas post-HD this was only 0.6 +/- 1.7 L (p < 0.001). Clinical overhydration was more prevalent in pre-HD and PD patients compared to post-HD patients (24.1% vs 22.3% vs 10%, p < 0.001). In multivariate models, overhydration was related to age, male gender, and post-HD status.

CONCLUSION

Although much clinical attention is paid to volume status, 24% of patients still have clinically relevant volume overload. Implementation of a reliable and clinically applicable tool to assess volume status is therefore necessary. It is possible to obtain comparable volume status in PD and HD patients.