The role of tidal peritoneal dialysis in modern practice: A European perspective

Tidal continuous cycling peritoneal dialysis in children

About 10% of all home peritoneal dialysis regimens in children with chronic kidney disease stage 5 are reported to involve some form of a tidal peritoneal dialysis (TPD) prescription. Despite this, there remain several gaps in how pediatric nephrologists approach the use of TPD. This stems from a combination of factors such as the confusing technical terminology pertaining to TPD, seemingly conflicting data on the risks, benefits, and indications for TPD, and lastly, limited published guidelines on the practical aspects of how to write a TPD prescription, based on the indication, in children. Our educational review, using evidence-based data, attempts to bridge this gap and provide an easy-to-use guide on the key practical aspects of TPD in children.

Wearable and implantable artificial kidney devices for end-stage kidney disease treatment-Current status and review

BACKGROUND

Chronic kidney disease (CKD) is a major cause of early death worldwide. By 2030, 14.5 million people will have end-stage kidney disease (ESKD, or CKD stage 5), yet only 5.4 million will receive kidney replacement therapy (KRT) due to economic, social, and political factors. Even for those who are offered KRT by various means of dialysis, the life expectancy remains far too low.

OBSERVATION

Researchers from different fields of artificial organs collaborate to overcome the challenges of creating products such as Wearable and/or Implantable Artificial Kidneys capable of providing long-term effective physiologic kidney functions such as removal of uremic toxins, electrolyte homeostasis, and fluid regulation. A focus should be to develop easily accessible, safe, and inexpensive KRT options that enable a good quality of life and will also be available for patients in less-developed regions of the world.

CONCLUSIONS

Hence, it is required to discuss some of the limits and burdens of transplantation and different techniques of dialysis, including those performed at home. Furthermore, hurdles must be considered and overcome to develop wearable and implantable artificial kidney devices that can help to improve the quality of life and life expectancy of patients with CKD.

Preliminary safety study of the Automated Wearable Artificial Kidney (AWAK) in Peritoneal Dialysis patients

BACKGROUND

Regeneration of peritoneal dialysis (PD) fluid using sorbent technology can provide flexibility and improve quality of life. This study examined the safety and efficacy of the automated wearable artificial kidney (AWAK) device in PD patients.

METHODS

This pilot study included prevalent PD patients from a single center in Singapore between 2016 and 2018. Participants underwent up to nine AWAK therapies over 72 h and were followed up for 1 month. Primary outcomes were serious adverse events (SAEs) and completion of nine therapies without device deficiency. Secondary outcomes were weekly peritoneal Kt/V _urea, solutes clearance and adverse events (AEs).

RESULTS

Twenty-one patients were screened and 15 were included in the study. Device alterations were required to overcome issues including flow occlusions initially, which resulted in three cohorts (n = 2, 2 and 11 respectively). No SAEs were observed during the study and at the follow-ups. Common AEs were abdominal pain/discomfort (60%) and bloatedness (47%). The median estimated peritoneal weekly Kt/V _urea was 3.0 (interquartile range: 2.2-4.8). There were significant reductions in pre- and post-study median serum urea (20.8 vs. 14.9 mmol/L; p = 0.001), creatinine (976.0 vs. 667.5 µmol/L; p = 0.001), phosphate (1.7 vs. 1.5 mmol/L; p = 0.03), and β2-microglobulin (29114.0 vs. 26339.0 µg/L; p = 0.048). Fluid reabsorption occurred among patients with residual kidney function. However, median body weights were not significantly different pre- and post-study (66.4 vs. 65.7 kg; p = 0.83).

CONCLUSIONS

This preliminary study demonstrated that no SAEs were observed with the AWAK-PD device; however, 60% of participants developed abdominal pain/discomfort. Further device enhancements are needed to improve ultrafiltration and reduce AEs.

The Occurrence of Increased Intraperitoneal Volume Events in Automated Peritoneal Dialysis in the US: Role of Programming, Patient/User Actions and Ultrafiltration

Background, objectives and methods

Increased intraperitoneal volume (IIPV) can occur during automated peritoneal dialysis (APD). The contribution of factors such as cycler programming and patient/user actions to IIPV has not been previously explored. The relationship between IIPV and cycler programming, patient/user actions, and ultra-filtration over a two-year period was investigated using US data from Baxter cyclers. Drain/fill volume ratios of > 1.6 to ≤ 2.0 and > 2.0 were defined as Level I and Level II IIPV events, respectively.

Results

Level I IIPV events occurred in 2.39% of standard and 4.73% of small fill volume therapies, while Level II IIPV events occurred in 0.26% and 1.33% of therapies, respectively. IIPV events occurred significantly more often in association with tidal peritoneal dialysis (PD) compared to non-tidal PD therapies. In tidal therapies, IIPV events were primarily related to suboptimal programming of total ultrafiltration volume. Factors that increased the odds of IIPV events during standard therapies included programming the initial drain volume target to < 70% of the last fill, and setting minimum drain volumes to < 85% of the fill volume. Bypass of initial drain by patients/users was also associated with a significant increase in the odds of IIPV events in non-tidal, but not tidal PD. An increase in the odds for IIPV was also seen for standard therapies within the highest (> 1,245 mL) versus the lowest (< 427 mL) quartile of ultrafiltration. Similar trends were seen in small fill volume therapies. Clinical presentations associated with IIPV events were not assessed.

Conclusions

IIPV events are more frequent in tidal and small fill volume therapies. The greatest potential for IIPV occurred when the total ultrafiltration was set too low for the patient's UF requirements during tidal therapy. Patient/user bypass of drains without reaching the target drain volume contributes significantly to IIPV events in non-tidal PD therapies. Poorly functioning PD catheters may be central to the cycler programming and patient/user actions that lead to IIPV.

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.

Optimizing Automated Peritoneal Dialysis Using an Extended 3-Pore Model

Introduction

In the current study, an extended 3-pore model (TPM) is presented and applied to the problem of optimizing automated peritoneal dialysis (APD) with regard to osmotic water transport (UF), small/middle-molecule clearance, and glucose absorption.

Methods

Simulations were performed for either intermittent APD (IPD) or tidal APD (TPD). IPD was simulated for fill and drain volumes of 2 L, whereas TPD was simulated using a tidal volume of 0.5 L, 1 L, or 1.5 L with full drains and subsequent fills (2 L) occurring after every fifth dwell. A total of 25 cycles for a large number of different dialysate flow rates (DFR) were simulated using 3 different glucose concentrations (1.36%, 2.27%, and 3.86%) and 3 different peritoneal transport types: slow (peritoneal equilibrium test D/P_crea < 0.6), fast (peritoneal equilibrium test D/P_crea > 0.8), and average. Solute clearance and UF were simulated to occur during the entire dwell, including both fill and drain periods.

Results

It is demonstrated that DFRs exceeding ∼ 3 L/h are of little benefit both for UF and small-solute transport, whereas middle-molecule clearance is enhanced at higher DFRs. The simulations predict that large reductions (> 20%) in glucose absorption are possible by using moderately higher DFRs than a standard 6 × 2 L prescription and by using shorter optimized “bi-modal” APD regimens that alternate between a glucose-free solution and a glucose-containing solution.

Discussion

Reductions in glucose absorption appear to be significant with the proposed regimens for APD; however, further research is needed to assess the feasibility and safety of these regimens.

Intermittent peritoneal dialysis: urea kinetic modeling and implications of residual kidney function

BACKGROUND

Intermittent peritoneal dialysis (IPD) is an old strategy that has generally been eclipsed, in the home setting, by daily peritoneal therapies. However, for a select group of patients with exhausted vascular access or inability to receive PD at home, in-center IPD may remain an option or may serve as an incremental strategy before initiation of full-dose PD. We investigated the residual kidney clearance requirements necessary to allow thrice-weekly IPD regimens to meet current adequacy targets.

METHODS

The 3-pore model of peritoneal transport was used to examine 2 thrice-weekly IPD dialysis modalities: 5 - 6 dwells with 10 - 12 L total volume (low-dose IPD), and 50% tidal with 20 - 24 L total volume (high-dose IPD). We assumed an 8-hour dialysis duration and 1.5% dextrose solution, with a 2-L fill volume, except in tidal mode. The PD Adequest application (version 2.0: Baxter Healthcare Corporation, Deerfield, IL, USA) and typical patient kinetic parameters derived from a large dataset [data on file from Treatment Adequacy Review for Gaining Enhanced Therapy (Baxter Healthcare Corporation)] were used to model urea clearances. The minimum glomerular filtration rate (GFR) required to achieve a total weekly urea Kt/V of 1.7 was calculated.

RESULTS

In the absence of any dialysis, the minimum residual GFR necessary to achieve a weekly urea Kt/V of 1.7 was 9.7 mL/min/1.73 m(2). Depending on membrane transport type, the low-dose IPD modality met urea clearance targets for patients with a GFR between 6.0 mL/min/1.73 m(2) and 7.6 mL/min/1.73 m(2). Similarly, the high-dose IPD modality met the urea clearance target for patients with a GFR between 4.7 mL/min/1.73 m(2) and 6.5 mL/min/1.73 m(2).

CONCLUSIONS

In patients with residual GFR of at least 7.6 mL/min/1.73 m(2), thrice-weekly low-dose IPD (10 L) achieved a Kt/V urea of 1.7 across all transport types. Increasing the IPD volume resulted in a decreased residual GFR requirement of 4.7 mL/min/1.73 m(2) (24 L, 50% tidal). In patients with residual kidney function and dietary compliance, IPD may be a viable strategy in certain clinical situations.