Method for pre-filling a hemodialysis apparatus

1. A method for pre-filling a hemodialysis apparatus, the method comprising:

providing a hemodialysis apparatus comprising:

a pre-filling liquid source configured to supply a pre-filling liquid,

a dialyzer,

a dialysate side comprising:

a dialysate chamber of the dialyzer, the dialysate chamber comprising a dialyzer membrane,

a dialysate pump configured to pump the pre-filling liquid to the dialysate chamber, and

a waste pump configured to pump the pre-filling liquid away from the dialysate chamber,

a blood side comprising:

an arterial line comprising an arterial line end,

a blood pump,

a blood chamber of the dialyzer, and

a venous line comprising a venous line end, and

a pressure sensor arranged on the dialysate side or on the blood side;

connecting the venous line end directly to the arterial line or connecting the arterial line end directly to the venous line;

pre-filling the arterial line and the venous line with the pre-filling liquid from the pre-filling liquid source by operating the dialysate pump; and

continuously determining a blood-side fluid pressure via the pressure sensor during the pre-filling,

wherein,

the pre-filling is stopped when the blood-side fluid pressure determined by the pressure sensor exceeds or falls below a defined limit pressure, and

the venous line end is not directly connected to the arterial line end.

2. The method as recited in claim 1 , wherein the pressure sensor is at least one of an arterial pressure sensor arranged along the arterial line and a venous pressure sensor arranged along the venous line.

3. The method as recited in claim 1 , wherein the pre-filling liquid source is a dialysate source, and the method further comprises pumping the pre-filling liquid with the dialysate pump through the dialyzer membrane into the arterial line and into the venous line during the pre-filling.

4. The method as recited in claim 1 , wherein the dialysate pump is coupled to the waste pump so as to form a balancing pump, the hemodialysis apparatus further comprises a separate ultra-filtration pump which is configured to be fluidically parallel to the waste pump, and wherein, during the pre-filling, the ultra-filtration pump is configured to operate in a reverse flow relative to the waste pump.

5. The method as recited in claim 1 , wherein the arterial line comprises an arterial line end, and wherein, during the pre-filling, a pumping rate of the blood pump towards the arterial line end is no higher than a pre-filling pumping rate at which the pre-filling liquid flows through the dialyzer membrane.

6. The method as recited in claim 1 , wherein the hemodialysis apparatus further comprises an air trap arranged along the venous line, the air trap comprising a pre-filling coupling which is configured to connect to the arterial line end during the pre-filling.

7. The method as recited in claim 6 , wherein the hemodialysis apparatus further comprises a venous line clip configured to be actuatable and which is arranged in the venous line between the air trap and the venous line end, and wherein the method further comprises a venting phase comprising:

stopping the pre-filling;

closing the venous line clip; and

operating the blood pump so as to pump the pre-filling liquid from the air trap through the venous line to the blood chamber.

8. The method as recited in claim 7 , wherein, during the venting phase, a pumping rate of the blood pump is varied at least once by at least 30%.

9. The method as recited in claim 7 , wherein the hemodialysis apparatus further comprises an arterial cannula arranged on the arterial line at the arterial line end and an arterial line clip arranged between the blood chamber and the arterial cannula, and wherein, during the venting phase between the closing of the venous line clip and the opening of the venous line clip, the method further comprises closing and opening the arterial line clip.

10. The method as recited in claim 9 , wherein the blood chamber remains in a vertical orientation during the pre-filling so that the venous line is connected at a bottom of the blood chamber, and the arterial line is connected at a top of the blood chamber.

11. The method as recited in claim 6 , wherein the pressure sensor is a venous pressure sensor which is arranged at the air trap.

12. The method as recited in claim 11 , wherein the air trap comprises an immersed tube with a tube opening arranged below a liquid level, the immersed tube being connected directly with the blood chamber of the dialyzer via a section of the venous line.