Apparatus and method for urea photo-oxidation

#More than 2 million end-stage renal disease (ESRD) patients worldwide receive dialysis to sustain life, with this number likely to represent less than 10% of the actual need. In the United States alone, over 460,000 people are on kidney dialysis, over 89,000 of whom die annually with a 5-year survival rate being only 35%. The intermittent character of hemodialysis causes large fluctuations in blood metabolite concentrations. Observations show that long-term survival in dialysis is improved for the patients treated by extended hemodialysis (i.e., more frequent or with longer hours of treatment) when compared to conventional hemodialysis.

#FIG. 1 is a plan view of a conventional dialysis system 10. In operation, a patient 5 is connected to the dialysis system 10 such that patient's blood flows through a tubing 14 into a dialysis system 10. The tubing 14 is threaded through a blood pump 18. The pumping action of the blood pump 18 pushes patient's blood through the dialysis system 10 and back into patient's body. The pump 18 is typically a non-contact pump.

#Dialysate 12 is a fluid that helps remove the unwanted waste products (e.g., urea) from patient's blood. During the dialysis, dialysate 12 and patient's blood flow through the dialysis system 10, but the two flows do not physically mix. Instead, fresh dialysate 12 from the machine is separated by a membrane from the blood flow. Impurities from patient's blood stream are filtered out through the membrane into dialysate 12. For example, typically 12-24 g of urea needs to be removed daily in a normal adult, but with a reduced protein diet 15 g day is a sufficient goal. Other impurities are also filtered out of the blood stream into the dialysate. Dialysate containing unwanted waste products and excess electrolytes leave the dialyzer for disposal.

#The foregoing aspects and many of the attendant advantages of the inventive technology will become more readily appreciated as the same are understood with reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

#FIG. 1 is a plan view of a dialysis system in accordance with conventional technology;

#FIG. 2 is a schematic diagram of a dialysis system in accordance with an embodiment of the present technology;

#While several embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the claimed subject matter.

#FIG. 2 is a schematic diagram of a dialysis system in accordance with an embodiment of the present technology. The illustrated system (e.g., a kidney dialysis system, hemodialysis, hemodiafiltration or a hemofiltration system) includes a urea oxidation unit 700 and a toxin selective removal unit 600. In operation, flow of blood 410 that includes urea and other toxins enters the urea oxidation unit 700. The flow of blood 410 is separated from a flow of dialysate fluid (e.g., dialysate) 715 by a membrane 712, which allows mass exchange for select molecules between the flow of blood and the flow of dialysate fluid (referred to as “dialysate” for simplicity). In some embodiments, a low molecular weight cut-off dialysis membrane allows only small molecules (e.g., less than 100 Da) to pass through. In some embodiments, the membrane may be a reverse osmosis (RO) membrane. In some embodiments, the urea oxidation unit 700 includes a photo-chemical oxidation unit 720 (also referred to as a “dialysis-fluid regeneration unit”, or a “urea treatment unit”) that is configured to remove urea, and a radical/trace scavenger 780 that is configured to remove oxidative byproducts, radical byproducts, chlorine, and/or other toxins. The photo-chemical oxidation unit 720 is described in more detail with reference to FIGS. 4A to 8 below. Terms “photo-oxidation,” “photochemical oxidation,” and “photo-chemical oxidation” are used interchangeably in this specification.

#In some embodiments, after urea and/or other small molecule toxins are removed from the blood flow 410, thus partially cleaned blood flow 414 continues to flow toward a protein-bound toxin selective removal unit 600. The blood flow 414 is separated from cellular components by a membrane 612 that is configured for passing large molecular weight proteins and small molecules, commonly referred to as blood plasma. On the permeate side of membrane 612 are selective sorbents for clearance of larger molecular weight and/or protein-bound toxins. This solution 614 flows through a membrane 613 into unit 650 with a mixture of sorbents and selective membranes for the removal of small molecule toxins through flow 610. Nutrients are returned to blood stream 416 as flow 651 as well as desorbed proteins in flow 616 on permeate/plasma side of membrane 612. Some non-exclusive examples of toxins 610 removed by the unit 600 are indoxyl sulfate that was bound to human albumin. Generally, the urea oxidation unit 700 removes small toxic molecules, while the toxin selective removal unit 600 removes large toxic molecules or those bound to proteins such as albumin. However, in different embodiments different arrangements of the toxin removal units are also possible. The blood and/or blood plasma flow 616 that exits from the toxin selective removal unit 600 continues to flow toward further elements/steps of the dialysis process or returns to the patient.