Dialysis system having disposable cassette

1. A dialysis system comprising:

a dialysis instrument;

a disposable cassette, the cassette including a rigid portion defining at least one pumping chamber, a pouch fitted over the rigid portion, the pouch including at least one flexible sheet, the at least one flexible sheet including

a folded top portion having an at least substantially flat surface,

a front face and a rear face each extending from the folded top portion, the front face and rear face each including first and second side edges and a bottom edge,

wherein at least a portion of the first side edge of the front face is sealed to the first side edge of the rear face, at least a portion of the second side edge of the front face is sealed to the second side edge of the rear face, and at least a portion of the bottom edge of the front face is sealed to the bottom edge of the rear face, so as to provide a sealed environment inside the pouch; and

wherein the instrument is configured to press the at least one flexible sheet against the at least one pumping chamber to seal the pumping chamber for operation.

2. The dialysis system of claim 1 , wherein the rigid portion includes a plurality of ports, the ports extending through the at least one sheet, the at least one sheet sealed to the ports.

3. The dialysis system of claim 2 , the ports extending through a seam of the at least one sheet.

4. The dialysis system of claim 2 , which includes tubes sealed to the ports outside of the pouch.

5. The dialysis system of claim 1 , which includes a plurality of tubes connected to the cassette, the tubes extending through the at least one sheet, the at least one sheet sealed to the tubes.

6. The dialysis system of claim 5 , the tubes extending through a seam of the at least one sheet.

7. The dialysis system of claim 5 , the tubes sealed to a plurality of ports extending from the rigid portion.

8. The dialysis system of claim 1 , wherein the rigid portion defines at least one valve chamber, the instrument configured to press the at least one sheet against the at least one valve chamber to seal the at least one valve chamber for operation.

9. The dialysis system of claim 1 , wherein the rigid portion defines at least one flow path, the instrument configured to press the at least one sheet against the at least one flow path to seal the at least one flow path for operation.

10. The dialysis system of claim 1 , wherein the at least one pumping chamber of the rigid portion is defined by a raised ridge surrounding a well, the instrument sealing the at least one flexible sheet to the raised ridge of the at least one pumping chamber.

11. The dialysis system of claim 1 , wherein the at least one sheet of the pouch is formed from a single sheet which is folded along one of a plurality of edges of the rigid portion.

12. The dialysis system of claim 1 , the instrument including (i) an inflatable bladder, the bladder inflating to press the at least one sheet against the at least one pumping chamber or (ii) a door, the door closing to mechanically press the at least one sheet against the at least one pumping chamber.

13. The dialysis system of claim 1 , the pouch including an excess area extending from the rigid portion, the excess area defining at least one alignment aperture for loading of the cassette into the instrument.

14. The dialysis system of claim 1 , wherein the pouch is of a material selected from the group consisting of: polyvinyl chloride (“PVC”), polyethylene, kraton and polyolefin.

15. The dialysis system of claim 1 , which includes locating guides, wherein the rigid portion of the disposable cassette includes locating holes, and the at least one flexible sheet includes alignment apertures, at least a portion of one of the locating guides configured to extend through the alignment apertures, one of the locating holes and an aperture defined in the other of the locating guides so as to secure the at least one flexible sheet to the cassette when loading the cassette into the instrument.