Peritoneal dialysis methods and apparatus
A peritoneal-based (“bloodless”) artificial kidney processes peritoneal fluid without need for additional fluids (“waterless”). Fluid is separated into a protein-rich stream and a protein-free stream. The protein-rich stream is regenerated using a sorbent assembly, and its protein composition can be modified by removal of selected protein(s) (“dialysate-pheresis”). It is then reconstituted with additives and returned into the peritoneal cavity, thereby reducing protein-loss and providing oncotic-pressure for ultrafiltration. The protein-free stream is used to produce free water, and an alkaline or acid fluid for optimization of the composition of the regenerated stream. The unused protein-free stream can be used to “reverse flush” the separator to maintain its patency and the excess discarded for fluid-balance regulation. Compared to prior art, immobilization of urease allows more protein rich fluid to be regenerated and re-circulated into the peritoneal cavity for toxin removal and allows practicable development of portable and wearable artificial kidneys.
1. A peritoneal dialysis system, comprising:
a first fluid line that carries a fluid stream from a peritoneal cavity of a user;
a separator that separates the fluid stream into a relatively protein-rich stream and a relatively protein-free stream, wherein the relatively protein-rich stream averages at least 15% (by vol) of the fluid stream over at least some period of time; and
a processing line that includes a sorbent system that is configured to remove at least one toxin from at least some of the protein-rich stream to thereby allow production of a modified dialysate stream;
a second fluid line that introduces at least some of the modified dialysate stream into the peritoneal cavity; and
wherein at least some of the sorbent system includes an enzyme that is immobilized on a substrate with greater than Van der Waals forces.
2. The peritoneal dialysis system of claim 1 , wherein the relatively protein-rich stream averages at least 40% (by vol) of the fluid stream from the peritoneal cavity over the at least some period of time.
3. The peritoneal dialysis system of claim 1 , wherein the relatively protein-rich stream averages at least 90% (by vol) of the fluid stream from the peritoneal cavity over the at least some period of time.
4. The peritoneal dialysis system of claim 1 , wherein the separator comprises a hollow fiber filter.
5. The peritoneal dialysis system of claim 1 , further comprising a pump that at least temporarily affects a ratio of the relatively protein-rich stream to the relatively protein-free stream.
6. The peritoneal dialysis system of claim 1 , wherein the sorbent system comprises a user-replaceable assembly having at least 100 gm of a sorbent.
7. The peritoneal dialysis system of claim 6 , wherein the user-replaceable sorbent assembly has a dry weight of no more than 5 kg.
8. The peritoneal dialysis system of claim 6 , wherein the user-replaceable sorbent assembly has a dry weight of no more than 2 kg.
9. The peritoneal dialysis system of claim 1 , wherein the processing line includes a processor comprising at least one of a cation exchanger and an anion exchanger, which alters a concentration in at least a portion of the relatively protein-free stream of at least one of H + , OH − , CO3 −− and HCO3 −− .
10. The peritoneal dialysis system of claim 1 , wherein the processing line includes a gas extractor disposed to operate upon at least a portion of the relatively protein-rich stream.
11. The peritoneal dialysis system of claim 1 , further comprising a monitor that measures a characteristic of the system.
12. The peritoneal dialysis system of claim 1 , further comprising a sodium monitor and feedback loop that maintains an average sodium concentration of at least a portion of the relatively protein-rich stream within a desired range over a period of at least 1 hour.
13. The peritoneal dialysis system of claim 1 , further comprising a pH monitor and feedback loop that maintains an average pH of at least a portion of the relatively protein-rich stream within a desired range over a period of at least 1 hour.
14. The peritoneal dialysis system of claim 1 , further comprising an ammonia detector and feedback loop that triggers an action when an ammonia concentration in at least a portion of the relatively protein-rich stream is greater than a predetermined value.
15. The peritoneal dialysis system of claim 1 , further comprising a glucose addition module, and at least one enrichment module that collectively adds at least two of potassium, calcium, and magnesium to at least a portion of the relatively protein-rich stream.
16. The peritoneal dialysis system of claim 1 , further comprising a unit that targets removal of a specific protein from at least a portion of the relatively protein-rich stream.
17. The peritoneal dialysis system of claim 1 , further comprising an ultrasonic vibrator that operates upon at least a portion of the relatively protein-rich stream and that is configured to facilitate solvation of additives.
18. The peritoneal dialysis system of claim 1 , wherein the second fluid line is operable concurrently with the first fluid line.
19. The peritoneal dialysis system of claim 1 , wherein the processing line, excluding a user-replaceable sorbent cartridge, has a dry weight of no more than 5 kg.
20. The peritoneal dialysis system of claim 1 , wherein the processing line excluding a user-replaceable sorbent assembly has a dry weight of no more than 2 kg.
21. The peritoneal dialysis system of claim 1 , wherein the processing line includes a gas removal unit disposed to operate upon at least a portion of the relatively protein-rich stream.
22. The peritoneal dialysis system of claim 1 , further comprising a power source sufficient to operate the processing line continuously for at least 7 hours.