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

Peritoneal dialysis in children, what's different: Your questions answered

Maintenance peritoneal dialysis (PD) is the most used kidney replacement therapy for children with kidney failure throughout the world. Underlying causes of kidney failure, indications for dialysis, body size, and nutritional requirements differ between children and adults on PD. These differences, along with the ongoing growth and development that occurs throughout childhood, impact PD access, prescription, and monitoring in children. This review highlights the unique challenges and management approaches to optimize the care of children on maintenance PD.

Trends in Automated Peritoneal Dialysis Prescriptions in a Large Dialysis Organization in the United States

Key Points

This is the largest analysis of incident automated peritoneal dialysis (PD) prescriptions conducted in the United States to date. There was limited variability of automated PD prescriptions across the first 4 months of therapy. PD prescriptions tailored to meet the dialysis needs and lifestyle of patients may make PD a more attractive choice and increase longevity on PD.

Background

Changes in health care policies and recognition of patient benefit have contributed to increases in home-based dialysis, including peritoneal dialysis (PD). Frequent monitoring and early individualization of PD prescriptions are key prerequisites for the delivery of high-quality PD. The present analysis aimed to assess variations in PD prescriptions among incident automated PD (APD) patients who remain on PD for 120+ days.

Methods

This retrospective analysis examined data from patients within a large dialysis organization that initiated PD with APD between 2015 and 2019. PD prescription data were described by calendar year, timing of PD, and residual renal function categories. Changes in prescriptions from PD initiation (day 1) to day 120 were assessed descriptively.

Results

The cohort included 11,659 patients. The mean age at PD initiation increased from 2015 (56 [15] years) through 2019 (58 [15] years), whereas most other variables demonstrated no clear temporal change. Most patients (86%) had nighttime PD prescribed, with an average of 4.9 (1.3) cycles per day, a mean total treatment volume of 9.3 (2.5) L, and a median daily total dwell time of 7 (6–9.5) hours. Relative to day 1 nighttime prescriptions, there were (1 ) small increases in the proportion of patients receiving three or fewer cycles per day and those receiving 6+ cycles per day, (2 ) a 100 ml mean increase in fill volume per exchange, and (3 ) a mean 0.5 L increase in total nighttime treatment volume at day 120. When changes in nighttime APD prescriptions were examined at the patient level, 49% of patients had day 120 prescriptions that were unchanged from their initial prescription.

Conclusions

In the largest analysis of incident APD prescriptions conducted in the United States to date, most patients were prescribed nocturnal PD only with limited variability across the first 4 months of therapy.

Relationship between intraperitoneal pressure and the development of hernias in peritoneal dialysis: confirmation for the first time of a widely accepted concept

BACKGROUND

Intraperitoneal pressure (IPP) in peritoneal dialysis (PD) is an individual characteristic that can be modified by posture and intraperitoneal volume (IPV). It is considered one of the predisposing factors for complications in the abdominal wall, such as the appearance of hernias. No studies to date have confirmed this. The main aim of this study was to assess the relationship between the development of hernia in incident PD patients and IPP measured at PD onset.

METHODS

A prospective observational study of incident patients in a PD programme between 2010 and 2020. IPP was measured using the Durand's method.

RESULTS

One hundred and twenty-four incident patients on PD, 68% male, mean age 62.1 ± 15.23 years, body mass index (BMI) 27.7 ± 4.82 kg/m2, 44% were diabetic. IPP in supine was 16.6 ± 4.60 cm H2O for a mean IPV of 2047.1 ± 359.19 mL. Hernias were reported in 18.5% of patients during PD follow-up: 57% were inguinal hernias, 33% umbilical, and a further 10% presented in a combined form. PD hernias correlated positively with IPP in supine position (p = 0.037), patient age (p = 0.008), BMI (p = 0.043), a history of prior hernia (0.016), laparoscopic catheter placement (p = 0.026), and technique failure (p = 0.012). In the multivariate analysis, a higher IPP was independently related to the development of hernias (p = 0.028).

CONCLUSIONS

The development of hernias in PD was related to a higher IPP at PD onset, older age, higher BMI, history of prior hernia, catheter placement by laparoscopy, and technique failure.

New perspectives in pediatric dialysis technologies: the case for neonates and infants with acute kidney injury

Advancements in pediatric dialysis generally rely on adaptation of technology originally developed for adults. However, in the last decade, particular attention has been paid to neonatal extracorporeal therapies for acute kidney care, an area in which technology has made giant strides in recent years. Peritoneal dialysis (PD) is the kidney replacement therapy (KRT) of choice in the youngest age group because of its simplicity and effectiveness. However, extracorporeal blood purification provides more rapid clearance of solutes and faster fluid removal. Hemodialysis (HD) and continuous KRT (CKRT) are thus the most used dialysis modalities for pediatric acute kidney injury (AKI) in developed countries. The utilization of extracorporeal dialysis for small children is associated with a series of clinical and technical challenges which have discouraged the use of CKRT in this population. The revolution in the management of AKI in newborns has started recently with the development of new CKRT machines for small infants. These new devices have a small extracorporeal volume that potentially prevents the use of blood to prime lines and dialyzer, allow a better volume control and the use of small-sized catheter without compromising the blood flow amount. Thanks to the development of new dedicated devices, we are currently dealing with a true "scientific revolution" in the management of neonates and infants who require an acute kidney support.

Renal replacement therapy modality in critically ill patients with acute kidney injury - A network meta-analysis of randomized controlled trials

PURPOSE

This network meta-analysis aims to compare the efficacy and safety of various renal replacement therapy (RRT) modalities in critically ill patients with acute kidney injury (AKI).

MATERIALS AND METHODS

We searched the electronic databases for randomized controlled trials (RCTs) comparing different RRT modalities, including continuous RRT, intermittent RRT, hybrid RRT, and peritoneal dialysis (PD), in critically ill patients with AKI through July 26, 2020. The primary outcomes were renal recovery and short-term mortality. The study protocol was registered with PROSPERO (CRD42020188115).

RESULTS

Twenty-three studies were included. No difference in the renal recovery or short-term mortality was observed among the four RRT modalities (low certainty). The four RRT modalities had similar effects on the incidence of infectious complications (low certainty). PD was associated with less fluid removal volume and lower incidence of hypotension compared with the extracorporeal modalities, yet no difference in the two outcomes was identified among the extracorporeal modalities (very low to moderate certainty).

CONCLUSIONS

No superiority of one particular RRT modality over another in terms of renal recovery and short-term mortality in critically ill patients with AKI. PD exhibited worse fluid removal and better safety in the prevention of hypotension than the extracorporeal modalities.

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.

Prescribing peritoneal dialysis for high-quality care in children

Background:

Peritoneal dialysis (PD) remains the most widely used modality for chronic dialysis in children, particularly in younger children and in lower and middle income countries (LMICs). We present guidelines for dialysis initiation, modality selection, small solute clearance, and fluid removal in children on PD. A review of the literature and key studies that support these statements are presented.

Methods:

An extensive Medline search for all publications on PD in children was performed using predefined search criteria.

Results:

High-quality randomized trials in children are scarce and current clinical practice largely relies on data extrapolated from adult studies or drawn from observational cohort studies in children. The evidence and strength of the recommendation is GRADE-ed, but in the absence of high-quality evidence, the opinion of the authors is provided and must be carefully considered by the treating physician, and adapted to local expertise and individual patient needs as appropriate. We discuss the timing of dialysis initiation, factors to be considered when selecting a dialysis modality, the assessment and management of volume status on PD, achieving optimal small solute clearance, and the importance of preserving residual kidney function. While optimal dialysis must remain the goal for every patient, a careful discussion with fully informed patients and caregivers is important to understand the patient and family’s expectations of dialysis and reasonable adjustments to the dialysis program may be considered in accordance with a philosophy of shared decision-making.

Conclusions:

There continues to be very poor evidence in the field of chronic PD in children and these recommendations can at best serve to guide clinical decision-making. In LMICs, every effort should be made to conform to the framework of these statements, taking into account resource limitations.

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.

Customization of Peritoneal Dialysis in Cardiorenal Syndrome by Optimization of Sodium Extraction

BACKGROUND

Peritoneal dialysis (PD) has emerged as a mechanistically relevant therapeutic option for patients with heart failure (HF), volume overload, and varying degrees of renal dysfunction (i.e., chronic cardiorenal syndrome). Congestion has been identified as a potent ominous prognostic factor in this patient population, outperforming a number of established risk factors. As such, excess fluid removal is recognized as a relevant therapeutic target in this setting.

METHODS

Accumulating evidence points to the importance of sodium removal as part of any decongestive strategy because extraction of sodium-free water has little or no impact on the outcomes of these patients. Hence, optimization of sodium removal by PD should be the primary focus in the setting of HF and cardiorenal syndrome, especially if PD is started when the patient still has adequate residual renal function for clearance of waste products.

RESULTS

Herein, we provide an overview of approaches that can tailor PD treatment to the patients' characteristics and clinical needs (e.g., choice of PD modality) to fully exploit its decongestive properties. Other methods that could prove helpful in the future will also be briefly discussed.

CONCLUSION

While these strategies could help with efficient sodium extraction and volume optimization, future studies are needed to evaluate their impact on the outcomes of this specific patient population.

Assessment and management of fluid overload in children on dialysis

Dysregulation of intravascular fluid leads to chronic volume overload in children with end-stage kidney disease (ESKD). Sequelae include left ventricular hypertrophy and remodeling and impaired cardiac function. As a result, cardiovascular complications are the commonest cause of mortality in the pediatric dialysis population. The clinical need to optimize intravascular volume in children with ESKD is clear; however, its assessment and management is the most challenging aspect of the pediatric dialysis prescription. Minimizing chronic fluid overload is a key priority; however, excessive ultrafiltration is toxic to the myocardium and can precipitate intradialytic symptoms. This review outlines emerging objective techniques to enhance the assessment of fluid overload in children on dialysis and outlines evidence for current management strategies to address this clinical problem.

Intraperitoneal pressure in peritoneal dialysis

The measure of intraperitoneal pressure in peritoneal dialysis is easy and provides clear therapeutic benefits. However it is measured only rarely in adult peritoneal dialysis units. This review aims to disseminate the usefulness of measuring intraperitoneal pressure. This measurement is performed in supine before initiating the drain of a manual exchange with "Y" system, by raising the drain bag and measuring from the mid-axillary line the height of the liquid column that rises from the patient. With typical values of 10-16 cmH₂O, intraperitoneal pressure should never exceed 18 cmH₂O. With basal values that depend on body mass index, it increases 1-3 cmH₂O/L of intraperitoneal volume, and varies with posture and physical activity. Its increase causes discomfort, sleep and breathing disturbances, and has been linked to the occurrence of leaks, hernias, hydrothorax, gastro-esophageal reflux and enteric peritonitis. Less known and valued is its ability to decrease the effectiveness of dialysis significantly counteracting ultrafiltration and decreasing solute clearance to a smaller degree. Because of its easy measurement and potential utility, should be monitored in case of ultrafiltration failure to rule out its eventual contribution in some patients. Although not yet mentioned in the clinical practice guidelines for PD, its clear benefits justify its inclusion among the periodic measurements to consider for prescribing and monitoring peritoneal dialysis.

Genomic reprograming analysis of the Mesothelial to Mesenchymal Transition identifies biomarkers in peritoneal dialysis patients

Peritoneal dialysis (PD) is an effective renal replacement therapy, but a significant proportion of patients suffer PD-related complications, which limit the treatment duration. Mesothelial-to-mesenchymal transition (MMT) contributes to the PD-related peritoneal dysfunction. We analyzed the genetic reprograming of MMT to identify new biomarkers that may be tested in PD-patients. Microarray analysis revealed a partial overlapping between MMT induced in vitro and ex vivo in effluent-derived mesothelial cells, and that MMT is mainly a repression process being higher the number of genes that are down-regulated than those that are induced. Cellular morphology and number of altered genes showed that MMT ex vivo could be subdivided into two stages: early/epithelioid and advanced/non-epithelioid. RT-PCR array analysis demonstrated that a number of genes differentially expressed in effluent-derived non-epithelioid cells also showed significant differential expression when comparing standard versus low-GDP PD fluids. Thrombospondin-1 (TSP1), collagen-13 (COL13), vascular endothelial growth factor A (VEGFA), and gremlin-1 (GREM1) were measured in PD effluents, and except GREM1, showed significant differences between early and advanced stages of MMT, and their expression was associated with a high peritoneal transport status. The results establish a proof of concept about the feasibility of measuring MMT-associated secreted protein levels as potential biomarkers in PD.

Should sodium removal in peritoneal dialysis be estimated from the ultrafiltration volume?

In peritoneal dialysis (PD), ultrafiltration (UF) volume is the sum of solute-free- and solute-coupled-water removal, a dynamic process throughout the entire dwell exerted via aquaporin-1 (AQP1) and small pores, respectively. Determination of sodium sieving is used as a parameter for AQP1 function analysis, while coupled water removal is essential for adequate sodium and water balance and thus blood pressure control. The diffusive capacity of glucose via the small pores determines the dynamic crystalloid osmotic gradient. The osmotic conductance, i.e., milliliter of UF per gram of glucose absorbed, quantifies cooperation between small-pores and AQP1 channels. In continuous ambulatory peritoneal dialysis, with dwell times beyond glucose-induced sodium-sieving effects, approximate dialytic sodium removal (DSR) may be estimated from the UF volume (in average 100 mmol Na/L UF), while DSR is lower, with shorter cycle times, in automated PD (APD); therefore, effluent sodium concentrations should be measured. Applying dialysis mechanics, i.e., varying dwell time and dwell volume-as proposed in adapted APD to the PD prescription-may provide unmatched high DSR relative to UF volume, findings which are not sufficiently explained by the three-pore model of PD. Overall DSR should therefore be measured rather than estimated from UF volume.

[Peritoneal equilibration test: Conventional versus adapted. Preliminary study]

Conventional automated peritoneal dialysis (APD) is prescribed as a repetition of cycles with the same dwell time and the same fill volume. Water and sodium balance remains a common problem among patients on peritoneal dialysis. More recently, adapted automated peritoneal dialysis was described, as a combination of short dwells with a low volume, in order to enhance ultrafiltration, followed by long dwells with a large fill volume to favor solute removal. We performed a preliminary crossover study on 4 patients. The total amount of dialysate was the same, i.e. 2L/m² as well as the total duration of the test, i.e. 150 minutes. The conventional test was made with two identical cycles, each cycle had a fill volume of 1L/m² and a duration of 75 minutes, while the adapted test was performed with one short cycle, i.e. 30 minutes with a low fill volume, i.e. 0.6L/m², followed by a long cycle, i.e. 120 minutes, with a large fill volume, i.e. 1.4L/m². Sodium extraction was improved by 29.3mmol/m² (169%) in the adapted test in comparison to the conventional test. Ultrafiltration was enhanced by 159mL/m² (128%) in the adapted test compared to the conventional one. Glucose absorption was decreased by 35% in the adapted test in comparison to the conventional test and osmotic conductance was also improved. In conclusion, adapted dialysis may allow for a better volume and sodium balance, since we observed an improvement in sodium extraction and ultrafiltration. This pre-study authorizes an improvement of the European Pediatric Study's protocol on Adapted APD, already started and which will continue in the next months.

Impact of fill volume on ultrafiltration with icodextrin in children on chronic peritoneal dialysis

BACKGROUND

Icodextrin is a solution of glucose polymers developed to provide sustained ultrafiltration over an extended dwell. Our aim was to determine whether or not fill volume with icodextrin contributes to the ability to achieve ultrafiltration in children.

METHODS

The charts of all children on chronic peritoneal dialysis between January 2000 and July 2014 were screened for the use of an icodextrin day dwell. Data were extracted from the electronic chart and the HomeChoice™ Pro card and corrected for body surface area (BSA).

RESULTS

Fifty children had an icodextrin day dwell. A linear correlation was found between the daytime fill volume and net ultrafiltration (p < 0.001). More ultrafiltration was achieved with a fill volume above 550 ml/m(2) BSA (107 ± 75 ml/m(2) BSA) than with smaller fill volumes (-8 ± 99 ml; p = 0.004). Ultrafiltration was achieved in 88 % of children with a fill volume above 550 ml/m(2) BSA versus only 44 % of patients with a smaller fill volume (p = 0.001). Icodextrin was well tolerated.

CONCLUSIONS

Our observations reveal that the larger the fill volume the higher the likelihood of achieving ultrafiltration with icodextrin and suggest that a minimum day dwell volume of 550 ml/m(2) BSA seems to facilitate ultrafiltration in children. To our knowledge this is the largest study addressing ultrafiltration with icodextrin in children.

Increasing sodium removal on peritoneal dialysis: applying dialysis mechanics to the peritoneal dialysis prescription

Optimal fluid removal on peritoneal dialysis (PD) requires removal of water coupled with sodium, which is predominantly achieved via the small pores in the peritoneal membrane. On the other hand, free-water transport takes place through aquaporin-1 channels, but leads to sodium retention and over hydration. PD prescription can be adapted to promote small pore transport to achieve improved sodium and fluid management. Both adequate dwell volume and dwell time are required for small pore transport. The dwell volume determines the amount of "wetted" peritoneal membrane being increased in the supine position and optimized at dwell volumes of approximately 1400 ml/m(2). Diffusion across the recruited small pores is time-dependent, favored by a long dwell time, and driven by the transmembrane solute gradient. According to the 3-pore model of conventional PD, sodium removal primarily occurs via convection. The clinical application of these principles is essential for optimal performance of PD and has resulted in a new approach to the automated PD prescription: adapted automated PD. In adapted automated PD, sequential short- and longer-dwell exchanges, with small and large dwell volumes, respectively, are used. A crossover trial in adults and a pilot study in children suggests that sodium and fluid removal are increased by adapted automated PD, leading to improved blood pressure control when compared with conventional PD. These findings are not explained by the current 3-pore model of peritoneal permeability and require further prospective crossover studies in adults and children for validation.

Is peritoneal dialysis still an equal option? Results of the Berlin pediatric nocturnal dialysis program

BACKGROUND

Peritoneal dialysis (PD) or conventional hemodialysis (HD) are considered to be equally efficient dialysis methods in children and adolescents. The aim of our study was to analyze whether an intensified, nocturnal HD program (NHD) is superior to PD in an adolescent cohort.

METHODS

Thirteen patients were prospectively enrolled in a NHD program. We measured uremia-associated parameters, parameters for nutrition, medication and blood pressure and analyzed the data. These data were compared to those of 13 PD controls, matched for gender, age and weight at the beginning the respective dialysis program and after 6 months of treatment.

RESULTS

Serum phosphate levels decreased significantly in the NHD group and remained unchanged in the PD group. Arterial blood pressure in the NHD was significantly lower despite the reduction of antihypertensive treatment, whereas blood pressure levels remained unchanged in the PD controls. Preexisting left ventricular hypertrophy resolved and albumin levels improved with NHD. Dietary restrictions could be lifted for those on NHD, whereas they remained in place for the patients on PD treatment. Residual diuresis remained unchanged after 6 months of either NHD or PD. NHD patients experienced fewer days of hospitalization than the PD controls.

CONCLUSIONS

Based on our results, NHD results in significantly improved parameters of uremia and nutrition. If individually and logistically possible, NHD should be the treatment modality of preference for older children and adolescents.

Mesenchymal Conversion of Mesothelial Cells Is a Key Event in the Pathophysiology of the Peritoneum during Peritoneal Dialysis

Peritoneal dialysis (PD) is a therapeutic option for the treatment of end-stage renal disease and is based on the use of the peritoneum as a semipermeable membrane for the exchange of toxic solutes and water. Long-term exposure of the peritoneal membrane to hyperosmotic PD fluids causes inflammation, loss of the mesothelial cells monolayer, fibrosis, vasculopathy, and angiogenesis, which may lead to peritoneal functional decline. Peritonitis may further exacerbate the injury of the peritoneal membrane. In parallel with these peritoneal alterations, mesothelial cells undergo an epithelial to mesenchymal transition (EMT), which has been associated with peritoneal deterioration. Factors contributing to the bioincompatibility of classical PD fluids include the high content of glucose/glucose degradation products (GDPs) and their acidic pH. New generation low-GDPs-neutral pH fluids have improved biocompatibility resulting in better preservation of the peritoneum. However, standard glucose-based fluids are still needed, as biocompatible solutions are expensive for many potential users. An alternative approach to preserve the peritoneal membrane, complementary to the efforts to improve fluid biocompatibility, is the use of pharmacological agents protecting the mesothelium. This paper provides a comprehensive review of recent advances that point to the EMT of mesothelial cells as a potential therapeutic target to preserve membrane function.