Dialysis system including automatic priming

1. A hemodialysis system comprising:

a source of priming fluid;

an extracorporeal circuit including an arterial line, a venous line, and a drip chamber;

a level sensor operable with the drip chamber;

a reversible blood pump operable with the extracorporeal circuit;

a connection between the arterial line and the venous line; and

a priming sequence in which priming fluid from the source is pumped in a reverse pump direction through the extracorporeal circuit and oppositely in a normal pump direction through the extracorporeal circuit, wherein an output from the level sensor is used to determine when to stop pumping in at least one of the directions.

2. The hemodialysis system of claim 1 , wherein the connection is made at non-dialyzer ends of the arterial and venous lines.

3. The hemodialysis system of claim 1 , wherein the priming fluid is saline.

4. The hemodialysis system of claim 1 , wherein the priming fluid is dialysate.

5. The hemodialysis system of claim 4 , wherein the extracorporeal circuit is in fluid communication with a dialyzer and the dialysate is pumped into the extracorporeal circuit through the dialyzer.

6. The hemodialysis system of claim 1 , wherein priming fluid in the priming sequence is pumped in the reverse pump direction multiple times through the extracorporeal circuit and oppositely in the normal pump direction multiple times through the extracorporeal circuit, and wherein an output from the level sensor is used at least one time to determine when to switch directions.

7. The hemodialysis system of claim 6 , wherein priming fluid is pumped in the reverse pump direction and oppositely in the normal pump direction until the extracorporeal circuit is fully primed.

8. The hemodialysis system of claim 1 , wherein the drip chamber is vented, and wherein air during the priming sequence is vented through the drip chamber.

9. The hemodialysis system of claim 1 , wherein the priming fluid is pumped initially through the extracorporeal circuit in the reverse pump direction.

10. The hemodialysis system of claim 1 , wherein the priming source includes a saline source in fluid communication with the extracorporeal circuit via a saline line, the saline line operable with a valve to selectively allow saline to flow to the extracorporeal circuit.

11. The hemodialysis system of claim 10 , wherein the saline line includes a first branch placed in fluid communication with the extracorporeal circuit on a first side of the blood pump and a second branch placed in fluid communication with the extracorporeal circuit on a second side of the blood pump, wherein the valve is a first valve operable with the first branch, and which includes a second valve operable with the second branch, the priming sequence opening and closing the first and second valves such that saline is pumped through the blood pump in both the reverse pump direction and oppositely in the normal pump direction.

12. A hemodialysis system comprising:

an extracorporeal circuit including an arterial line, a venous line, and a drip chamber;

a level sensor operable with the drip chamber;

a reversible blood pump operable with the extracorporeal circuit;

a connection between the arterial line and the venous line; and

a priming sequence in which fluid is pumped in a reverse pump direction multiple times through the extracorporeal circuit and in a normal pump direction multiple times through the extracorporeal circuit, wherein an output from the level sensor is used to determine when to stop pumping in at least one of the directions.

13. The hemodialysis system of claim 12 , wherein fluid is pumped in the reverse pump direction and the normal pump direction multiple times through the extracorporeal circuit until the extracorporeal circuit is fully primed.

14. The hemodialysis system of claim 1 , wherein the fluid is pumped initially through the extracorporeal circuit in the reverse pump direction.

15. The hemodialysis system of claim 1 , wherein the fluid is saline or dialysate.

16. A hemodialysis priming method comprising:

pumping a priming fluid in a first direction through an extracorporeal circuit including an arterial line connected at its distal end to a distal end of a venous line, the extracorporeal circuit further including a drip chamber operable with a level sensor;

enabling air to be displaced through the drip chamber as priming fluid is pumped in the first direction through the extracorporeal circuit;

stopping the pumping of the priming fluid in the first direction;

upon stopping the pumping of the priming fluid in the first direction, pumping the priming fluid in a second direction through the extracorporeal circuit including the arterial line connected at its distal end to the distal end of the venous line;

enabling air to be displaced through the drip chamber as priming fluid is pumped in the second direction through the extracorporeal circuit; and

stopping the pumping of the priming fluid in the second direction when the priming fluid reaches a predetermined level in the drip chamber as indicated by the level sensor.

17. The method of claim 16 , wherein enabling air to be displaced through the drip chamber includes enabling air to be displaced through a hydrophobic vent.

18. The method of claim 16 , wherein the first direction is a reverse pump direction and the second direction is a normal pump direction.

19. The method of claim 16 , wherein pumping priming fluid in the first and second directions includes using a blood pump to pump the priming fluid.

20. The method of claim 16 , wherein upon stopping the pumping of the priming fluid in the second direction, further pumping the priming fluid a second time in the first direction through the extracorporeal circuit including the arterial line connected at its distal end to the distal end of the venous line.