Strict volume control normalizes hypertension in peritoneal dialysis patients

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.

Why should we use a low sodium dialysis solution for peritoneal dialysis?

Overhydration is highly prevalent in patients on peritoneal dialysis (PD), with inappropriately high sodium load supposedly playing a central role in the pathophysiology of the conditions. Recent studies have revealed the novel role of the interstitium as a buffer system for sodium ions, and it has been reported that patients on dialysis, including PD, present increased levels of sodium in the interstitium, such as in subcutaneous tissue and muscle. Hence, therapy for correction of overhydration should target the excess extracellular volume and the excess sodium storage in the interstitium. The ultrafiltrate obtained using the currently available PD solutions is hypo- to isonatric as compared to serum, which is disadvantageous for prompt and efficient sodium removal from the body in patients with overhydration. In contrast, use of low sodium PD solutions is characterised by iso- to hypernatric ultrafiltrate, which may beneficial for reducing sodium storage in the interstitium. Trials of low sodium PD solutions have reported possible clinical merits, for example, decreased blood pressure, reduced dryness of mouth and decreased body water content as assessed using bioimpedance methods. Given these observations and the high prevalence of overhydration in current PD populations, it makes medical sense that low sodium solutions be positioned as the new standard solution in the future. However, for medical safety, that is, to avoid hyponatremia and excessive decreases in blood pressure, further studies are needed to establish the appropriate compositions and applications of low sodium solutions.

Does Renal Denervation a Reasonable Treatment Option in Hemodialysis-Dependent Patient with Resistant Hypertension? A Narrative Review

PURPOSE OF REVIEW

This narrative review aims to assess the pathophysiology, diagnosis, and treatment of resistant hypertension (RH) in end-stage kidney disease (ESKD) patients on dialysis, with a specific focus on the effect of renal denervation (RDN) on short-term and long-term blood pressure (BP) control. Additionally, we share our experience with the use of RDN in an amyloidotic patient undergoing hemodialysis with RH.

RECENT FINDINGS

High BP, an important modifiable cardiovascular risk factor, is often observed in patients in ESKD, despite the administration of multiple antihypertensive medications. However, in clinical practice, it remains challenging to identify RH patients on dialysis treatment because of the absence of specific definition for RH in this context. Moreover, the use of invasive approaches, such as RDN, to treat RH is limited by the exclusion of patients with reduced renal function (eGFR < 45 mL/min/1.73 m3) in the clinical trials. Nevertheless, recent studies have reported encouraging results regarding the effectiveness of RDN in stage 3 and 4 chronic kidney disease (CKD) and ESKD patients on dialysis, with reductions in BP of nearly up to 10 mmhg. Although multiple underlying pathophysiological mechanisms contribute to RH, the overactivation of the sympathetic nervous system in ESKD patients on dialysis plays a crucial role. The diagnosis of RH requires both confirmation of adherence to antihypertensive therapy and the presence of uncontrolled BP values by ambulatory BP monitoring or home BP monitoring. Treatment involves a combination of nonpharmacological approaches (such as dry weight reduction, sodium restriction, dialysate sodium concentration reduction, and exercise) and pharmacological treatments. A promising approach for managing of RH is based on catheter-based RDN, through radiofrequency, ultrasound, or alcohol infusion, directly targeting on sympathetic overactivity.

Diagnosis and treatment of hypertension in dialysis patients: a systematic review

In patients with end-stage renal disease (ESRD) undergoing dialysis, hypertension is common but often inadequately controlled. The prevalence of hypertension varies widely among studies because of differences in the definition of hypertension and the methods of used to measure blood pressure (BP), i.e., peri-dialysis or ambulatory BP monitoring (ABPM). Recently, ABPM has become the gold standard for diagnosing hypertension in dialysis patients. Home BP monitoring can also be a good alternative to ABPM, emphasizing BP measurement outside the hemodialysis (HD) unit. One thing for sure is pre- and post-dialysis BP measurements should not be used alone to diagnose and manage hypertension in dialysis patients. The exact target of BP and the relationship between BP and all-cause mortality or cause-specific mortality are unclear in this population. Many observational studies with HD cohorts have almost universally reported a U-shaped or even an L-shaped association between BP and all-cause mortality, but most of these data are based on the BP measured in HD units. Some data with ABPM have shown a linear association between BP and mortality even in HD patients, similar to the general population. Supporting this, the results of meta-analysis have shown a clear benefit of BP reduction in HD patients. Therefore, further research is needed to determine the optimal target BP in the dialysis population, and for now, an individualized approach is appropriate, with particular emphasis on avoiding excessively low BP. Maintaining euvolemia is of paramount importance for BP control in dialysis patients. Patient heterogeneity and the lack of comparative evidence preclude the recommendation of one class of medication over another for all patients. Recently, however, β-blockers could be considered as a first-line therapy in dialysis patients, as they can reduce sympathetic overactivity and left ventricular hypertrophy, which contribute to the high incidence of arrhythmias and sudden cardiac death. Several studies with mineralocorticoid receptor antagonists have also reported promising results in reducing mortality in dialysis patients. However, safety issues such as hyperkalemia or hypotension should be further evaluated before their use.

Plant-Based Diets and Peritoneal Dialysis: A Review

Whole food plant-based diets are gaining popularity as a preventative and therapeutic modality for numerous chronic health conditions, including chronic kidney disease, but their role and safety in end-stage kidney disease patients on peritoneal dialysis (PD) is unclear. Given the general public’s increased interest in this dietary pattern, it is likely that clinicians will encounter individuals on PD who are either consuming, considering, or interested in learning more about a diet with more plants. This review explores how increasing plant consumption might affect those on PD, encompassing potential benefits, including some specific to the PD population, and potential concerns.

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.

A Comparison of Hemodialysis and Peritoneal Dialysis in Patients with Cardiovascular Disease

The high prevalence of cardiovascular disease is caused by the traditional cardiovascular risk factors common among end-stage renal disease patients, and nontraditional risk factors attributed to underlying kidney disease, including chronic inflammation, anemia, bone mineral disease, and the dialysis procedure itself. Individualization of the treatment of cardiovascular disease in end-stage renal disease that could impact the underlying mechanisms of the cardiovascular diseases is important to improve outcomes. This article reviews and compares hemodialysis and peritoneal dialysis in association with different cardiovascular diseases affecting dialysis patients, including hypertension, coronary artery disease, myocardial stunning, cardiac arrhythmias, heart failure, and the cardiorenal syndrome.

KDOQI US Commentary on the 2020 ISPD Practice Recommendations for Prescribing High-Quality Goal-Directed Peritoneal Dialysis

The recently published 2020 International Society for Peritoneal Dialysis (ISPD) practice recommendations regarding prescription of high-quality goal-directed peritoneal dialysis differ fundamentally from previous guidelines that focused on "adequacy" of dialysis. The new ISPD publication emphasizes the need for a person-centered approach with shared decision making between the individual performing peritoneal dialysis and the clinical care team while taking a broader view of the various issues faced by that individual. Cognizant of the lack of strong evidence for the recommendations made, they are labeled as "practice points" rather than being graded numerically. This commentary presents the views of a work group convened by the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) to assess these recommendations and assist clinical providers in the United States in interpreting and implementing them. This will require changes to the current clinical paradigm, including greater resource allocation to allow for enhanced services that provide a more holistic and person-centered assessment of the quality of dialysis delivered.

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.

Hemodialysis crossover study using a relative blood volume change-guided ultrafiltration control compared with standard hemodialysis: the BV-UFC study

Background

It has been difficult to sufficiently achieve body-fluid management using blood volume (BV) monitor during hemodialysis (HD) with constant ultrafiltration (UF) rate. Recently, a relative BV change-guided UF control (BV-UFC) system was developed by combining the concepts of an automatic feedback system that could control the UF rate and profile with real- time monitoring of relative changes in BV (%ΔBV). However, this system has limited application in the clinical setting. Therefore, in this study, we aimed to perform the crossover study on HD with BV-UFC compared to standard HD in terms of hemodynamic stability during HD.

Methods

Forty-eight patients entered an 8-week crossover period of standard HD or HD with BV-UFC. Prevalence of intradialytic hypotension (IDH) as a primary outcome and changes in blood pressure (BP), differences in %ΔBV, and achievement of the target ultrafiltration volume as secondary outcomes were compared. IDH was defined as a reduction in systolic BP ≥20 mmHg from the baseline value at 10 min after HD initiation.

Results

No significant differences were found in the prevalence of IDH, frequency of intervention for symptomatic IDH, and achievement of the target ultrafiltration volume between the groups. The %ΔBV was significantly fewer (-12.1 ± 4.8% vs. -14.4 ± 5.2%, p <0.001) in the HD with BV-UFC than that in the standard HD.

Conclusions

HD with BV-UFC did not reduce the prevalence of IDH compared with standard HD. The relief of a relative BV reduction at the end of HD may be beneficial in patients undergoing HD with BV-UFC.

Trial Registration

UMIN, UMIN000024670. Registered on December 1, 2016.

Sodium Removal in Patients Undergoing CAPD and Automated Peritoneal Dialysis

Objectives

To compare sodium removal in continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD) patients, and to identify the main factors that modify Na removal in clinical practice in these patients.

Design

Study in three steps. Cross-sectional observational (Study A), and longitudinal interventional (Studies B and C).

Patients and Methods

First (Study A) we carried out a cross-sectional survey of Na removal in 63 patients on CAPD and 78 patients on APD. Second (Study B), we studied Na removal in 32 patients before and after changing from CAPD to APD therapy. Finally (Study C), we analyzed the impact on Na removal of introducing icodextrin for the long dwell in 16 patients undergoing CAPD or APD.

Results

In Study A, total Na removal averaged 210 mmol/day for CAPD patients and 91 mmol/day for APD patients ( p < 0.001); Na removal was < 100 mmol/day in 7.1% of CAPD patients and 56.4% of APD patients. Multivariate analysis identified ultrafiltration [B = 125 mmol/day, 95% confidence interval (CI) 110, 140], CAPD therapy (B = 60 mmol/day, 95%CI 37, 83), and residual diuresis (B = 51 mmol/L, 95%CI 34, 69) as independent predictors of Na removal (adjusted r2 = 0.76). For APD patients, longer nocturnal dwell times and performing a supplementary diurnal exchange were also independently associated with higher Na removal rates. In Study B, Na removal decreased from 192 to 92 mmol/day (median) after the change to APD ( p = 0.02). In Study C, peritoneal Na removal increased from 98 to 148 mmol/day (median) ( p = 0.04) after introducing icodextrin.

Conclusions

Standard APD schedules are frequently associated with poor Na removal rates. For any degree of ultrafiltration, Na removal is better in CAPD than in APD. Icodextrin, supplementary diurnal exchanges, and longer nocturnal dwell times improve Na removal in APD. Sodium removal can be estimated from ultrafiltration in patients on CAPD, but must be specifically monitored in patients on APD.

Improving Salt Balance in Peritoneal Dialysis Patients

Volume homeostasis is an important predictor of outcome in peritoneal dialysis. Because volume retention is driven by salt retention, maintenance of salt balance should be a concern to all nephrologists. An important factor in this is dietary salt restriction. This has long been neglected in peritoneal dialysis patients, where it was considered that the continuous nature of the therapy and residual renal function would be sufficient to remove any extra salt load. In patients with preserved renal function, diuresis and salt excretion can be enhanced by the application of high doses of loop diuretics. This practice seems not to have an impact on the further deterioration of renal function. Peritoneal salt removal can be enhanced using polyglucose. Also, the use of low sodium-containing dialysate can be efficient. These solutions are, however, not commercially available, and they need higher concentrations of glucose to obtain an efficient osmolarity. It should always be considered that, due to sodium sieving over the ultrasmall pores, fluid and salt removal are not always concordant.

Blood Pressure Control and Left Ventricular Hypertrophy in Long-Term Capd and Hemodialysis Patients: A Cross-Sectional Study

Background

It is still not clear whether hypertension and left ventricular hypertrophy (LVH) are more common in continuous ambulatory peritoneal dialysis (CAPD) than in hemodialysis (HD) patients.

Methods

To examine this subject, the indices of cardiac performance were compared between 50 HD and 34 CAPD patients. Patients were further divided into two subgroups [long-term (L) CAPD and L-HD] according to dialysis modality and duration of dialysis (more than 60 months’ duration).

Results

The blood pressure and cardiothoracic index of CAPD patients did not differ from HD patients. On average, the left atrial index was 2 mm/m2higher in HD patients than in CAPD patients. Left ventricular chamber sizes, wall thickness, and left ventricular mass index (LVMI) in patients on CAPD were similar to those of HD patients. Isovolumic relaxation time (IVRT) of CAPD patients was insignificantly less than that of HD patients (101 ± 22 and 115 ± 27 msec respectively). There was no significant difference between the two subgroups (L-HD and L-CAPD) in blood pressure, left atrial diameter, left ventricular chamber size, wall thickness, LVMI, ejection fraction, or IVRT.

Conclusion

If normovolemia and normotension are obtained by strict volume control without using antihypertensive drugs, the effects of the two modalities of chronic dialysis treatment (HD and CAPD) on cardiac structure and function are not different from each other.

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.

Fluid Status, Blood Pressure, and Cardiovascular Abnormalities in Patients on Peritoneal Dialysis

♦ Objective

Hypertension, reduced arterial distensibility, and left ventricular hypertrophy (LVH) are risk factors for mortality in hemodialysis patients. However, few studies have focused on the relation between fluid status, blood pressure (BP), and cardiovascular abnormalities in peritoneal dialysis (PD) patients. This study was designed, first, to assess, using tracer dilution techniques, fluid status in PD patients compared to a control population of stable renal transplant (RTx) patients; second, to study the relation between fluid status, BP, and arterial wall abnormalities; third, to assess the determinants of cardiac structure; and last, to compare office and ambulatory BP measurements with respect to cardiac abnormalities.

♦ Design

Cross-sectional study.

♦ Setting

Multicenter study.

♦ Patients

41 stable PD patients with a mean Kt/V urea of 2.4 ± 0.7, and 77 stable RTx patients.

♦ Intervention

Fluid status was assessed by tracer dilution techniques: extracellular volume (ECV) with bromide dilution; total body water (TBW) with deuterium oxide; and plasma volume (PV) with dextran 70. Echocardiography was performed to assess left ventricular mass (LVM), left ventricular end diastolic diameter (LVEDD), and relative wall thickness as indicators of LVH. Echography of the common carotid artery was performed to assess arterial distensibility. Both office and 24-hour ambulatory BP measurements were performed.

♦ Results

Fluid status, as assessed by ECV corrected for body surface area (BSA) (ECV:BSA), was significantly different between PD and RTx patients (9.4 ± 2.6 vs 8.6 ± 1.2 L/m2, p < 0.05). In 36.6% of the PD patients, ECV:BSA was above the 90th percentile of the RTx patients. Fluid status corrected for BSA, assessed by TBW (TBW:BSA), ECV (ECV:BSA), or plasma volume (PV:BSA), was significantly related to diastolic BP (DBP) ( r = 0.35, r = 0.37, r = 0.53; p < 0.05). Arterial distensibility of the common carotid artery was related to systolic BP (SBP) ( r = –0.36, p < 0.05). ECV was significantly related to LVEDD ( r = 0.41, p < 0.05) as a marker of eccentric LVH, whereas arterial distensibility was related to relative wall thickness ( r = –0.53, p < 0.001) as a marker of concentric LVH. An abnormal day–night BP rhythm, which was not related to fluid status, was observed in 68.4% of patients. Ambulatory DBP and SBP but not office DBP and SBP were related to LVM ( r = 0.43, r = 0.46; p < 0.01).

♦ Conclusions

A large proportion of PD patients whose treatment prescriptions are in accordance with the Dialysis Outcomes Quality Initiative guidelines were found to be overhydrated compared with a population of stable RTx patients. Fluid status was significantly related to DBP and eccentric LVH, whereas arterial distensibility of the common carotid artery was significantly related to SBP and concentric LVH. In contrast to ambulatory BP, office BP was not related to LVM.

The Association of Peritoneal Transport Properties with 24-Hour Blood Pressure Levels in Capd Patients

← Objectives

We aimed to investigate the effects of peritoneal transport characteristics on blood pressure (BP) parameters, measured by 24-hour ambulatory blood pressure monitoring (ABPM), and on the development of left ventricular hypertrophy (LVH) in continuous ambulatory peritoneal dialysis (CAPD) patients.

← Design

Cross-sectional and prospective design.

← Setting

Tertiary-care center.

← Patients

25 CAPD patients (11 male, 14 female; mean age 47 ± 14 years) were included. Mean time on CAPD was 22.9 ± 18 months and all patients had been dialyzed for more than 6 months. The patients were divided into high, high-average, low-average, and low transport groups according to peritoneal equilibration test results.

← Main Outcome Measures

Daytime and nighttime systolic and diastolic BP and left ventricular mass index among the different peritoneal transport groups; changes in BP parameters before and after increase in ultrafiltration.

← Results

On 24-hour ABPM records, 13 patients (52%) were found to be hypertensive. Both mean systolic and diastolic BP were significantly increased in high-transporter groups compared to low transporters in both daytime and nighttime BP parameters. Left ventricular mass index was higher in high transporters compared to low transporters, without reaching statistical significance: 160 ± 23 vs 119 ± 41 g/m2, p > 0.05. Following increase in ultrafiltration, mean systolic (145 ± 13 vs 128 ± 5 mmHg, p < 0.001) and diastolic (96 ± 10 vs 81 ± 3 mm Hg, p < 0.001) BP decreased, and BP levels returned to normotensive levels in 6 (46%) of the 13 hypertensive patients, requiring discontinuation of antihypertensive drugs.

← Conclusion

Improvement in volume status resulted in a decrease in both daytime and nighttime BP. Differences in peritoneal transport properties were associated with the development of hypertension and LVH.

Negotiated Care Improves Fluid Status in Diabetic Peritoneal Dialysis Patients

Background

Volume overload is common in diabetic patients on continuous ambulatory peritoneal dialysis (PD), especially when the patient's residual renal function decreases with time on PD. Due to the higher dietary salt and fluid intake, diabetic PD patients tend to use more hyper-tonic glucose solution to remove excess fluid, which in turn may lead to increased membrane permeability. In the present study, we investigated the effect of negotiated care on fluid status in diabetic PD patients.

Methods

All diabetic PD patients who had been on PD for at least 3 months by the end of year 2002 in the First Hospital of Peking University were included in the present study. A primary nurse was assigned to each patient and intensive patient education was implemented, focusing on the importance of dietary salt and fluid restriction, the detrimental effect of using more hypertonic glucose solution, and the consequence of fluid overload. Decisions on dialysis prescriptions were made after extensive discussion among the primary nurse, nephrologists, patients, and patients’ families. A patient support group was also involved when it was necessary. All the patients were followed for 1 year and fluid status, compliance to dietary restriction, and dialysis prescription were evaluated before the start and at the end of the study.

Results

There were 30 diabetic PD patients (age 65.4 ± 10.3 years; on PD for 24.5 ± 19.9 months, range 3 – 66 months) included in the study when it was started. During the 1 year of follow-up, 4 patients died of diabetic complications, 3 patients were transferred to hemodialysis due to resistant peritonitis, and 2 patients were transplanted. By the end of follow-up, 21 patients remained on PD, among whom 15 had improved fluid status, 4 did not change, and 2 had worsened fluid status as assessed by clinical and bio-impedance evaluation. Patient compliance to dietary salt and fluid restriction had increased from 19.5% to 76.2%. During the follow-up, 8 patients were anuric at the beginning of the study and the remaining 22 patients had declining residual renal function. Only 4 patients increased their use of hypertonic solution including 2.5% (3 patients) and 4.25% (1 patient) glucose, whereas 5 patients decreased their use of 2.5% dialysis solution. By the end of follow-up, only 1 of the 21 patients was using 4.25% glucose solution and all the patients had good blood glucose control.

Conclusions

Our results suggest that negotiated care can be successfully used in diabetic PD patients. It helps to minimize the use of hypertonic glucose solution and improves patient compliance to dietary restriction of salt and fluid intake, and thus improves their fluid status.

Volume Control Associated with Better Cardiac Function in Long-Term Peritoneal Dialysis Patients

Background

This study was undertaken to investigate the effect of long-term blood pressure (BP) reduction, achieved with salt restriction and strict volume control, on frequency and regression of left ventricular hypertrophy (LVH) in long-term peritoneal dialysis (PD) patients.

Methods

56 patients who had been treated for more than 2 years under our care were enrolled. After echocardiographic (Echo) evaluation, 46 patients were included in the follow-up study. In our unit, we aim to keep patients’ BP below 130/85 mmHg and cardiothoracic index below 0.50. To reach these targets, moderate salt restriction is advised, and if necessary, hypertonic PD solutions are used. Echo was performed at the beginning of the study (after a mean period of 36 months on PD) and at the end of the prospective follow-up period (24 months later).

Results

At the time of the first Echo, LVH was detected in only 8 (21%) patients. Residual urine volume was significantly decreased compared to data taken when they first started PD (658 ± 795 vs 236 ± 307 mL/day). Mean left ventricular mass index (LVMI) was 107 ± 26.5 g/m2. LVMI was significantly decreased at the end of the follow-up in patients who had LVH at baseline. No LVH developed in patients who had normal LVMI at baseline.

Conclusion

Our results indicate that control of hypertension is possible when extracellular fluid volume is kept under control using hypertonic PD solutions in case of recruitment in addition to salt restriction in long-term PD patients. Sustained normovolemia is associated with low incidence and regression of LVH.

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.

Changes in Total Sodium Intake Do Not Lead to Proportionate Changes in Total Sodium Removal in CAPD Patients

Background

Dietary salt and fluid restriction is important in controlling fluid balance in patients on continuous ambulatory peritoneal dialysis (CAPD). However, it is often difficult to monitor patients’ dietary total sodium intake (TSI). Usually, total sodium removal (TSR), the sum of urinary sodium removal (USR) and dialysate sodium removal (DSR), is suggested to represent TSI. In the present study, we investigated the reliability of using TSR as a surrogate to TSI in CAPD patients.

Methods

40 clinically stable CAPD patients were closely followed for 3 months. Their TSI, USR, DSR, and fluid status were measured twice: at baseline and at the end of this study respectively. Fluid status was evaluated by bioimpedance analysis. Patients with increased sodium intake (group ISI) or decreased sodium intake (group DSI) (both >0.5 g/day or >21.74 mmol/day elemental sodium) were included in this study.

Results

There were 15 patients in group ISI and 9 patients in group DSI. During the follow-up, although TSI increased in group ISI and decreased in group DSI ( p < 0.05), there were no significant changes in USR, DSR, or TSR in either group. No relationship was found between TSI and TSR. Changes in weight, blood pressure, urine volume, ultra-filtration, and small solute removal (Kt/V and creatinine clearance) were not statistically significant between the two groups. Fluid status deteriorated in group ISI and improved in group DSI ( p < 0.05).

Conclusions

Our study suggests that changes in total sodium intake do not lead to proportionate changes in total sodium removal in CAPD patients. Therefore, TSR (the sum of USR and DSR) should be used cautiously to monitor TSI in this patient population.

Prescribing peritoneal dialysis and achieving good quality dialysis in low and low-middle income countries

The provision of long-term renal replacement therapies for patients with end-stage kidney disease (ESKD) in low and low-middle income countries (LLMICs) has been a pervasive challenge, impeded mainly by monetary constraints, limited health-care resources, and geographical and logistic difficulties. Even for patients who could initiate dialysis, discontinuation of dialysis treatment due to the lack of financial sustainability is a valid concern. While the delivery of high-quality dialysis should not be compromised in these settings, perpetuity on dialysis is of paramount consideration for these patients, with sustaining life being just as important as achieving clinical well-being. As intensification of peritoneal dialysis (PD) prescription comes with immense cost in these settings, the strategy for stretching affordability of dialysis involves optimizing the number of PD exchanges required or delaying the transition to a high PD dose of four bags per day of continuous ambulatory PD (CAPD) prescription. This can be accomplished through the use of low-cost adjunctive treatment, by preserving residual kidney function and adopting incremental PD. The use of expensive, complex, or inaccessible monitoring tools for peritoneal membrane function and dialysis clearance could be replaced by clinical assessment and widely available biochemical indicators, which will significantly reduce the investigation costs, with consequent savings that could allow for lengthening the duration of PD therapy. Finally, it is important for each PD program in LLMICs to monitor these outcome indicators, to ensure the consistent delivery of acceptable quality of PD to their patients.

Volume management as a key dimension of a high-quality PD prescription

BACKGROUND

Appropriate volume control is one of the key goals in a peritoneal dialysis (PD) prescription. As such it is an important component of the International Society of Peritoneal Dialysis (ISPD) guideline for "High-quality PD prescription" necessitating a review of the literature on volume management. The workgroup recognized the importance of including within its scope measures of volume status and blood pressure in prescribing high-quality PD therapy.

METHODS

A Medline and PubMed search for publications addressing volume status and its management in PD since the publication of the 2015 ISPD Adult Cardiovascular and Metabolic Guidelines, from October 2014 through to July 2019, was conducted.

RESULTS

There were no randomized controlled trials on blood pressure intervention and six randomized trials of bioimpedance-guided volume management. Generally, all studies were of small sample size, short duration, and used surrogate markers as primary outcomes. As a consequence, only "practice points" were drawn. High-quality goal-directed PD prescription should aim to achieve and maintain clinical euvolemia taking residual kidney function and its preservation into account, so that both fluid removal from peritoneal ultrafiltration and urine output are considered and residual kidney function is not compromised. Blood pressure should be included as a key objective parameter in assessing the quality of PD prescription but there is currently no evidence for a specific target in PD. Clinical examination remains the keystone of routine clinical care.

CONCLUSIONS

High-quality goal-directed PD prescription should include volume management as one of the key dimensions.

Assessment and Management of Hypertension among Patients on Peritoneal Dialysis

Approximately 7%-10% of patients with ESKD worldwide undergo peritoneal dialysis (PD) as kidney replacement therapy. The continuous nature of this dialytic modality and the absence of acute shifts in pressure and volume parameters is an important differentiation between PD and in-center hemodialysis. However, the burden of hypertension and prognostic association of BP with mortality follow comparable patterns in both modalities. Although management of hypertension uses similar therapeutic principles, long-term preservation of residual diuresis and longevity of peritoneal membrane function require particular attention in the prescription of the appropriate dialysis regimen among those on PD. Dietary sodium restriction, appropriate use of icodextrin, and limited exposure of peritoneal membrane to bioincompatible solutions, as well as adaptation of the PD regimen to the peritoneal transport characteristics, are first-line therapeutic strategies to achieve adequate volume control with a potential long-term benefit on technique survival. Antihypertensive drug therapy is a second-line therapeutic approach, used when BP remains unresponsive to the above volume management strategies. In this article, we review the available evidence on epidemiology, diagnosis, and treatment of hypertension among patients on PD and discuss similarities and differences between PD and in-center hemodialysis. We conclude with a call for randomized trials aiming to elucidate several areas of uncertainty in management of hypertension in the PD population.

Plasma syndecan-1 in hemodialysis patients associates with survival and lower markers of volume status

Syndecan-1, a transmembrane heparan sulfate proteoglycan, associates with renal and cardiovascular functioning. We earlier reported syndecan-1 to be involved in renal tubular regeneration. We now examined plasma values of syndecan-1 in a hemodialysis cohort and its association with volume and inflammatory and endothelial markers in addition to outcome. Eighty-four prevalent hemodialysis patients were evaluated for their plasma syndecan-1 levels by ELISA before the start of hemodialysis, as well as 60, 180, and 240 min after start of dialysis. Patients were divided into sex-stratified tertiles based on predialysis plasma syndecan-1 levels. We studied the association between plasma levels of syndecan-1 and volume, inflammation, and endothelial markers and its association with cardiovascular events and all-cause mortality using Kaplan-Meier curves and Cox regression analyses with adjustments for gender, age, diabetes, and dialysis vintage. Predialysis syndecan-1 levels were twofold higher in men compared with women ( P = 0.0003). Patients in the highest predialysis plasma syndecan-1 tertile had a significantly higher ultrafiltration rate ( P = 0.034) and lower plasma values of BNP ( P = 0.019), pro-ANP ( P = 0.024), and endothelin ( P < 0.0001) compared with the two lower predialysis syndecan-1 tertiles. No significant associations with inflammatory markers were found. Cox regression analysis showed that patients in the highest syndecan-1 tertile had significantly less cardiovascular events and better survival compared with the lowest syndecan-1 tertile ( P = 0.02 and P = 0.005, respectively). In hemodialysis patients, higher plasma syndecan-1 levels were associated with lower concentrations of BNP, pro-ANP, and endothelin and with better patient survival. This may suggest that control of volume status in hemodialysis patients allows an adaptive tissue regenerative response as reflected by higher plasma syndecan-1 levels.

Renal Association Clinical Practice Guideline on peritoneal dialysis in adults and children

These guidelines cover all aspects of the care of patients who are treated with peritoneal dialysis. This includes equipment and resources, preparation for peritoneal dialysis, and adequacy of dialysis (both in terms of removing waste products and fluid), preventing and treating infections. There is also a section on diagnosis and treatment of encapsulating peritoneal sclerosis, a rare but serious complication of peritoneal dialysis where fibrotic (scar) tissue forms around the intestine. The guidelines include recommendations for infants and children, for whom peritoneal dialysis is recommended over haemodialysis.Immediately after the introduction there is a statement of all the recommendations. These recommendations are written in a language that we think should be understandable by many patients, relatives, carers and other interested people. Consequently we have not reworded or restated them in this lay summary. They are graded 1 or 2 depending on the strength of the recommendation by the authors, and A-D depending on the quality of the evidence that the recommendation is based on.

Numerical expression of volume status using the bioimpedance ratio in continuous ambulatory peritoneal dialysis patients: A pilot study

BACKGROUND

Volume overload results in higher mortality rates in patients on continuous ambulatory peritoneal dialysis (CAPD). The ratio of bioimpedance (RBI) might be a helpful parameter in adjusting dry body weight in CAPD patients. This study examined whether it is possible to distinguish between non-hypervolemic status and hypervolemic status in CAPD patients by using only RBI.

METHODS

RBI was calculated as follows: RBI = impedance at 50 kHz/impedance at 500 kHz. Based on the experts' judgements, a total of 64 CAPD patients were divided into two groups, a non-hypervolemic group and a hypervolemic group. The RBI was measured from right wrist to right ankle (rw-raRBI) by bioimpedance spectroscopy (BCM®, Fresenius Medical Care) before and after the peritosol was emptied. Other RBIs were measured from the right side of the anterior superior iliac spine to the ipsilateral ankle (rasis-raRBI) to control for the electro-physiological effects of peritoneal dialysate.

RESULTS

The mean rw-raRBI of non-hypervolemic patients was higher than that of hypervolemic patients in the presence (1.141 ± 0.022 vs. 1.121 ± 0.021, P < 0.001) of a peritosol. Likewise, the mean rasis-raRBI of non-hypervolemic patients was higher than that of hypervolemic patients (presence of peritosol: 1.136 ± 0.026 vs. 1.109 ± 0.022, P < 0.001; absence of peritosol: 1.131 ± 0.022 vs. 1.107 ± 0.022, P < 0.001).

CONCLUSION

The volume status of CAPD patients was able to be simply expressed by RBI. Therefore, this study suggests that when patients cannot be analyzed using BCM, RBI could be an alternative.

Setting the dry weight and its cardiovascular implications

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

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

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

The Use of a Multidimensional Measure of Dialysis Adequacy-Moving beyond Small Solute Kinetics

Urea removal has become a key measure of the intensity of dialysis treatment for kidney failure. Small solute removal, exemplified by Kt/Vurea, has been broadly applied as a means to quantify the dose of thrice weekly hemodialysis. Yet, the reliance on small solute clearances alone as a measure of dialysis adequacy fails fully to quantify the intended clinical effects of dialysis therapy. This review aims to (1) understand the strengths and limitations of small solute kinetics as a surrogate marker of dialysis dose, and (2) present the prospect of a more comprehensive construct for dialysis dose, one that considers more broadly the goals of ESRD care to maximize both quality of life and survival. On behalf of the American Society of Nephrology Dialysis Advisory Group, we propose the need to ascertain the validity and utility of a multidimensional measure that moves beyond small solute kinetics alone to quantify optimal dialysis derived from both patient-reported and comprehensive clinical and dialysis-related measures.

Impact of fluid status and inflammation and their interaction on survival: a study in an international hemodialysis patient cohort

In hemodialysis patients extracellular fluid overload is a predictor of all-cause and cardiovascular mortality, and a relation with inflammation has been reported in previous studies. The magnitude and nature of this interaction and the effects of moderate fluid overload and extracellular fluid depletion on survival are still unclear. We present the results of an international cohort study in 8883 hemodialysis patients from the European MONDO initiative database where, during a three-month baseline period, fluid status was assessed using bioimpedance and inflammation by C-reactive protein. All-cause mortality was recorded during 12 months of follow up. In a second analysis a three-month baseline period was added to the first baseline period, and changes in fluid and inflammation status were related to all-cause mortality during six-month follow up. Both pre-dialysis estimated fluid overload and fluid depletion were associated with an increased mortality, already apparent at moderate levels of estimated pre-dialysis fluid overload (1.1-2.5L); hazard ratio 1.64 (95% confidence interval 1.35-1.98). In contrast, post-dialysis estimated fluid depletion was associated with a survival benefit (0.74 [0.62-0.90]). The concurrent presence of fluid overload and inflammation was associated with the highest risk of death. Thus, while pre-dialysis fluid overload was associated with inflammation, even in the absence of inflammation, fluid overload remained a significant risk factor for short-term mortality, even following improvement of fluid status.

Nutrition in Older Adults on Peritoneal Dialysis

Nutrition in older adults on peritoneal dialysis is an important aspect of a patient's clinical management as well as being influenced by their overall well-being, both mental and physical. This is especially pertinent as individuals age, since the potential impact of life changes and physical changes contribute to the development of protein-energy wasting and potentially exacerbating sarcopenia and wasting. This article provides an outline of the nutritional issues to consider in older adults on peritoneal dialysis (PD).

Effect of Icodextrin Solution on the Preservation of Residual Renal Function in Peritoneal Dialysis Patients: A Randomized Controlled Study

Although icodextrin solution has been highlighted in the fluid management compared to glucose-based solutions, proof of a beneficial effect of icodextrin solution on residual renal function (RRF) is lacking. We conducted a multicenter prospective randomized controlled open-label trial to investigate whether icodextrin solution can preserve RRF.One hundred patients with urine volume ≥750 mL/day from 8 centers in Korea were randomly assigned to receive 1 exchange of icodextrin solution for a ≥8 hour-dwell time and 2 exchanges of 1.5% glucose-based biocompatible neutral pH solution or 1 exchange of ≥2.5% and 2 exchanges of 1.5% glucose-based biocompatible solutions. Using mixed-effects general linear models, we analyzed changes in residual glomerular filtration rate (GFR) and daily urine volume at 1 year.Forty-nine patients were assigned to the icodextrin group and 51 to the glucose solution group. During follow-up, the slope of the decline in residual GFR was -0.170 mL/min/month/1.73 m² in the icodextrin group, while it was -0.155 mL/min/month/1.73 m² in the glucose solution group (95% confidence interval [CI], -0.06 to 0.10; P = 0.701). Daily urine volume decreased faster in the glucose solution group than in the icodextrin group (-31.02 vs -11.88 mL per month; 95% CI, -35.85 to -2.44; P = 0.025). Results were consistent when we analyzed using intention-to-treat and per protocol principles. There were no differences in fluid status, peritoneal ultrafiltration, and peritoneal transport between groups during follow-up.This study clearly showed that icodextrin solution preserves residual urine volume better than glucose solution.

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.