Dialysis system having disposable cassette

1. A dialysis system comprising:

a dialysis instrument including three pump actuators;

a disposable cassette including: a rigid portion defining (i) three dialysate pump chambers positioned and arranged to operate with the three pump actuators of the dialysis instrument, and (ii) a flowpath having a plurality of sections, the flowpath allowing fluid communication between the three dialysate pump chambers; and

a controller operable with the three dialysate pump actuators to cause (i) a pump-out stroke of a second one of the three dialysate pump chambers to begin while a pump-out stroke of a first one of the three dialysate pump chambers is taking place; and (ii) a pump-out stroke of a third one of the three dialysate pump chambers to begin while the pump-out stroke of the second one of the three dialysate pump chambers is taking place.

2. The dialysis system of claim 1 , wherein the three pump actuators are pneumatic pump actuators.

3. The dialysis system of claim 1 , wherein the three dialysate pump chambers and the flowpath reside on different sides of the rigid portion of the disposable cassette.

4. The dialysis system of claim 3 , wherein the disposable cassette includes a flexible sheet secured to the rigid portion, the flexible sheet forming part of the three dialysate pump chambers.

5. The dialysis system of claim 4 , wherein the three pump actuators are pneumatic pump actuators configured to apply positive or negative pressure to the flexible sheet to pump dialysis fluid into and out of the three dialysate pump chambers.

6. The dialysis system of claim 3 , wherein the rigid portion includes a base wall with ridges extending from the base wall, the ridges defining a plurality of valve chambers.

7. The dialysis system of claim 3 , wherein ports extend outwardly from a bottom of the rigid portion of the disposable cassette, the ports connected fluidly to sources of fluid.

8. The dialysis system of claim 1 , wherein the plurality of sections of the flowpath include manifold sections and baffled sections, the baffled sections extending between the manifold sections.

9. The dialysis system of claim 8 , wherein the three dialysate pump chambers are aligned in a row.

10. The dialysis system of claim 1 , the controller further operable with the three pump actuators to cause (i) a chamber-fill stroke of the second one of the three dialysate pump chambers to begin while a chamber-fill stroke of the first one of the three dialysate pump chambers is taking place; and (ii) a chamber-fill stroke of the third one of the three dialysate pump chambers to begin while the chamber-fill stroke of the second one of the three dialysate pump chambers is taking place.

11. The dialysis system of claim 1 , wherein the controller is further operable with the three pump actuators to cause the three pump actuators to pause the three dialysate pump chambers at least one of (i) before a pump-fill stroke or (ii) after a pump-fill stroke.

12. The dialysis system of claim 1 , wherein the controller is configured to operate with the three pump actuators to (i) start a dialysis pump-out stroke for a second one of the three dialysate pump chambers during a dialysis pump-out stroke of a first one of the three dialysate pump chambers; and (ii) start a dialysis pump-out stroke of a third one of the three dialysate pump chambers to begin during the dialysis pump-out stroke of the second one of the three dialysate pump chambers.

13. The dialysis system of claim 1 , wherein the controller is configured to operate with the three pump actuators to (i) start a dialysis chamber-fill stroke of the second one of the three dialysate pump chambers during a dialysis chamber-fill stroke of the first one of the three dialysate pump chambers; and (ii) start a dialysis chamber-fill stroke of the third one of the three dialysate pump chambers during the dialysis chamber-fill stroke of the second one of the three dialysate pump chambers.

14. The dialysis system of claim 1 , wherein the controller is configured to operate with the three pump actuators to pause the three dialysate pump chambers before or after a dialysis pump-fill stroke.

15. The dialysis system of claim 1 , wherein the controller is configured to operate with the three pump actuators to start a dialysate chamber fill-stroke of the first one of the three dialysate pump chambers during a dialysate pump-out stroke of the third one of the three dialysate pump chambers.

16. A dialysis system comprising:

a dialysis instrument including three pump actuators;

a disposable cassette including three dialysate pump chambers positioned and arranged to operate with the three dialysate pump actuators of the dialysis instrument; and

a controller operable with the three pump actuators to cause (i) first and second ones of the three dialysate pump chambers to pump-out together, splitting discharged fluid from the first and second ones of the three dialysate pump chambers between fluid to a patient and fluid to a third one of the three dialysate pump chambers; and (ii) the third one of the three dialysate pump chambers to pump-out to the patient while the first and second ones of the three dialysate pump chambers perform a chamber-fill stroke.

17. The dialysis system of claim 16 , wherein the first and second ones of the three dialysate pump chambers are connected fluidly to different sources of fluid for mixing.

18. The dialysis system of claim 16 , wherein the discharged fluid from the first and second ones of the three dialysate pump chambers is a mixed fluid.

19. The dialysis system of claim 16 , wherein the splitting of the discharged fluid between the patient and the third one of the three dialysate pump chambers causes about half of the discharged fluid to be sent to the patient and about half of the discharged fluid to be sent to the third one of the three dialysate pump chambers.

20. The dialysis system of claim 16 , wherein the controller is configured to cycle back-and-forth between (i) and (ii) a plurality of times.