Urea removal strategies for dialysate regeneration in a wearable artificial kidney

Gelder, Maaike K. van; Jong, Jacobus A.W.; Folkertsma, Laura; Guo, Yong; Bluchel, Christian G.; Verhaar, Marianne C.; Odijk, Mathieu; Nostrum, Cornelus F. van; Hennink, Wim E.; Gerritsen, Karin G.F.

doi:10.1016/j.biomaterials.2019.119735

Cited by 89 publications

(101 citation statements)

References 154 publications

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“…To improve the quality of life of dialysis patients, wearable artificial kidney devices are being developed which use a small volume of dialysate (preferably <0.5 L) that is continuously regenerated by a purification unit and re‐used in a closed loop system 2–4. Removal of urea from dialysate is a major challenge in the realization of such a wearable dialysis device,5,6 since urea has low reactivity and high aqueous solubility while it is the metabolite with the highest daily molar production (240–470 mmol day −1 ) 7,8. It has been estimated that a urea clearance of 25–49 mL min −1 is needed in a 8‐h dialysis session to keep the urea concentration below 20 m m .…”

Section: Introductionmentioning

confidence: 99%

“…It has been estimated that a urea clearance of 25–49 mL min −1 is needed in a 8‐h dialysis session to keep the urea concentration below 20 m m . [6] Several strategies for urea removal from dialysate have been explored,6 including enzymatic hydrolysis,9,10 electro‐oxidation,11 and adsorption of urea 12–16. However, each of these strategies has drawbacks that do not allow reduction of the dialysate volume to <0.5 L as required for a wearable device 6,17…”

Section: Introductionmentioning

confidence: 99%

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A Ninhydrin‐Type Urea Sorbent for the Development of a Wearable Artificial Kidney

Jong

Guo

Hazenbrink

et al. 2020

Macromolecular Bioscience

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The aim of this study is to develop polymeric chemisorbents with a high density of ninhydrin groups, able to covalently bind urea under physiological conditions and thus potentially suitable for use in a wearable artificial kidney. Macroporous beads are prepared by suspension polymerization of 5‐vinyl‐1‐indanone (vinylindanone) using a 90:10 (v/v) mixture of toluene and nitrobenzene as a porogen. The indanone groups are subsequently oxidized in a one‐step procedure into ninhydrin groups. Their urea absorption kinetics are evaluated under both static and dynamic conditions at 37 °C in simulated dialysate (urea in phosphate buffered saline). Under static conditions and at a 1:1 molar ratio of ninhydrin: urea the sorbent beads remove ≈0.6–0.7 mmol g−1 and under dynamic conditions and at a 2:1 molar excess of ninhydrin ≈0.6 mmol urea g−1 sorbent in 8 h at 37 °C, which is a step toward a wearable artificial kidney.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Ninhydrin‐Type Urea Sorbent for the Development of a Wearable Artificial Kidney

Jong

Guo

Hazenbrink

et al. 2020

Macromolecular Bioscience

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confidence: 99%

“…Currently, no efficient urea sorbent is available for application in a wearable artificial kidney[42]. As the affinity of urea for activated carbon is relatively low (0.1-0.2 mmol/g), a relatively large amount of activated carbon (1.2-4.7 kg) would be required to remove the daily urea production[42]. Htay et al report use of enzymatic hydrolysis of urea by urease for dialysate regeneration in a wearable artificial kidney for CFPD, a system of <2 kg using 3 cartridges and 3 exchanges of 2 L per day[5,19].Urea removal by urease was first applied in the REcirculation DialYsis (REDY) sorbent system in HD[8]51].…”

mentioning

confidence: 99%

“…Although a urease-based sorbent system may allow miniaturization of the system to wearable proportions, the technology is complex and has several disadvantages. Toxic ammonium is generated during hydrolysis of urea that must be removed almost completely from dialysate by zirconium phosphate (cation exchanger), that binds ammonium in exchange for sodium and hydrogen, risking sodium release into the patient and acid base disturbances, respectively[42]. In addition, zirconium phosphate binds calcium, magnesium and too much potassium which must be re-infused from a separate reservoir.…”

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confidence: 99%

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In vitro efficacy and safety of a system for sorbent-assisted peritoneal dialysis

Gelder

Ligabue

Giovanella

et al. 2020

American Journal of Physiology-Renal Physiology

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A system for sorbent-assisted peritoneal dialysis (SAPD) was designed to continuously recirculate dialysate via a tidal mode using a single lumen peritoneal catheter with regeneration of spent dialysate by means of sorbent technology. We hypothesize that SAPD treatment will maintain a high plasma-to-dialysate concentration gradient and increase the mass transfer area coefficient of solutes. Thereby, the SAPD system may enhance clearance while reducing the number of exchanges. Application is envisaged at night as a bedside device (12 kg, nighttime system). A wearable system (2.0 kg, daytime system) may further enhance clearance during the day. Urea, creatinine, and phosphate removal were studied with the daytime and nighttime system ( n = 3 per system) by recirculating 2 liters of spent peritoneal dialysate via a tidal mode (mean flow rate: 50 and 100 mL/min, respectively) for 8 h in vitro. Time-averaged plasma clearance over 24 h was modeled assuming one 2 liter exchange/day, an increase in mass transfer area coefficient, and 0.9 liters ultrafiltration/day. Urea, creatinine, and phosphate removal was 33.2 ± 4.1, 5.3 ± 0.5, and 6.2 ± 1.8 mmol, respectively, with the daytime system and 204 ± 28, 10.3 ± 2.4, and 11.4 ± 2.1 mmol, respectively, with the nighttime system. Time-averaged plasma clearances of urea, creatinine and phosphate were 9.6 ± 1.1, 9.6 ± 1.7, and 7.0 ± 0.9 mL/min, respectively, with the nighttime system and 10.8 ± 1.1, 13.4 ± 1.8, and 9.7 ± 1.6 mL/min, respectively, with the daytime and nighttime system. SAPD treatment may improve removal of uremic toxins compared with conventional peritoneal dialysis, provided that peritoneal mass transport will increase.

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Catalytic urea electrooxidation on nickel‐metal hydroxide foams for use in a simplified dialysis device

Pyka,

Bergsman,

Stuve

2024

AIChE Journal

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Electrocatalytic urea removal is a promising technology for artificial kidney dialysis and wastewater treatment. Urea electrooxidation was studied on nickel electrocatalysts modified with Cr, Mo, Mn, and Fe. Mass transfer limits were observed for urea oxidation at physiological concentrations (10 mmol L). Urea oxidation kinetics were explored at higher concentrations (200 mmol L), showing improved performance, but with lower currents per active site. A simplified dialysis model was developed to examine the relationship of mass transfer coefficients and extent of reaction on flowrate, composition, and pH of the reacting stream. For a nickel hydroxide catalyst operating at 1.45 V, 37 , and pH 7.1, the model shows a minimum geometric electrode area of 1314 cm2 is needed to remove 3.75 g urea h with a flow rate of 200 mL min for continuous operation.

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Urea removal strategies for dialysate regeneration in a wearable artificial kidney

Cited by 89 publications

References 154 publications

A Ninhydrin‐Type Urea Sorbent for the Development of a Wearable Artificial Kidney

A Ninhydrin‐Type Urea Sorbent for the Development of a Wearable Artificial Kidney

In vitro efficacy and safety of a system for sorbent-assisted peritoneal dialysis

Catalytic urea electrooxidation on nickel‐metal hydroxide foams for use in a simplified dialysis device

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