Dialysis system having disposable cassette and heated cassette interface

1. A dialysis fluid flow control system comprising:

a disposable cassette including at least one pump chamber;

a pumping cassette interface including a pump area operable with the at least one pump chamber of the disposable cassette;

the cassette interface further including a volumetric reference chamber used in a volumetric control of a dialysis fluid pumped pneumatically into and out of the at least one pump chamber of the disposable cassette, the volumetric reference chamber configured and arranged to hold gas and not liquid while the dialysis fluid is pumped into and out of the at least one pump chamber of the disposable cassette;

a heater connected operably to the cassette interface; and

a controller connected operably to the heater so as to cause the heater to heat at least a portion of the cassette interface to a desired temperature.

2. The dialysis fluid flow control system of claim 1 , the controller and the heater operable to heat the volumetric reference chamber to the desired temperature.

3. The dialysis fluid flow control system of claim 1 , the pump area located on a first side of the interface, the volumetric reference chamber located on a second side of the interface.

4. The dialysis fluid flow control system of claim 1 , wherein the at least one pump chamber of the disposable cassette includes a plurality of pump chambers, and the cassette interface further includes at least one of a valve area operable with a valve chamber of the disposable cassette and a plurality of pump areas operable with the plurality of pump chambers of the disposable cassette.

5. The dialysis fluid flow control system of claim 1 , the cassette interface including a metal plate, the volumetric reference chamber formed in the metal plate.

6. The dialysis fluid flow control system of claim 1 , wherein the desired temperature to which the controller is configured to heat the cassette interface is a temperature that a corresponding disposable cassette reaches on average when dialysis fluid is pumped through the cassette.

7. The dialysis fluid flow control system of claim 1 , wherein the volumetric reference chamber is filled with a thermally conductive filler.

8. The dialysis fluid flow control system of claim 1 , wherein the cassette interface is at least one of (i) made of a thermally conductive material and (ii) fitted with a conductive heating strip to which the heater is connected.

9. The dialysis fluid flow control system of claim 1 , which includes a temperature sensor positioned to sense a temperature of the cassette interface, the temperature sensor outputting to the controller.

10. The dialysis fluid flow control system of claim 1 , which includes a valve connected operably to the volumetric reference chamber, the valve allowing the reference chamber to become pressurized.

11. The dialysis fluid flow control system of claim 1 , wherein the heater is coupled to the cassette interface.

12. A dialysis fluid flow control system comprising:

a disposable cassette including a pump chamber;

a pumping cassette interface including a pump area operable with the pump chamber of the disposable cassette;

a volumetric reference chamber used in a volumetric control of a dialysis fluid pumped into and out of the pump chamber of the disposable cassette, the volumetric reference chamber configured and arranged to hold a fixed volume of sealed gas while the dialysis fluid is pumped into and out of the pump chamber of the disposable cassette;

a heater connected operably to the volumetric reference chamber; and

a controller connected operably to the heater so as to cause the heater to heat the volumetric reference chamber to a desired temperature.

13. The dialysis fluid flow control system of claim 12 , wherein the volumetric reference chamber is coupled to the cassette interface.

14. The dialysis fluid flow control system of claim 12 , wherein the volumetric reference chamber is a molded plastic piece.

15. The dialysis fluid flow control system of claim 14 , wherein the volumetric reference chamber includes pneumatic fittings attached to the molded plastic piece.

16. The dialysis fluid flow control system of claim 12 , wherein the heated volumetric reference chamber is placed in direct contact with the pump area of the cassette interface.

17. The dialysis fluid flow control system of claim 12 , wherein the desired temperature to which the controller is configured to heat the cassette interface is a temperature that the disposable cassette reaches on average when dialysis fluid is pumped through the cassette.

18. The dialysis fluid flow control system of claim 12 , wherein the heater is coupled to the volumetric reference chamber.

19. A dialysis fluid flow control system comprising:

a disposable cassette including a pump chamber;

a volumetric reference chamber used in a volumetric control of a dialysis fluid pumped into and out of the pump chamber of the disposable cassette, the volumetric reference chamber configured and arranged to hold gas and not liquid while the dialysis fluid is pumped into and out of the pump chamber of the disposable cassette;

a heater connected operably to the volumetric reference chamber; and

a controller connected operably to the heater so as to cause the heater to heat the volumetric reference chamber to a desired temperature.

20. The dialysis fluid flow control system of claim 19 , which includes a pumping cassette interface including a pump area operable with the pump chamber of the disposable cassette, the volumetric reference chamber coupled to the pumping cassette interface.