METHOD OF FLUSHING AN EXTRACORPOREAL BLOOD CIRCUIT

Abstract

The invention relates to a method of flushing an extracorporeal blood circuit, preferably an extracorporeal blood circuit of a dialysis machine, with a flushing liquid, wherein the flushing liquid contains an anticoagulant agent, preferably heparin. The invention further relates to an extracorporeal blood treatment unit, preferably to a dialysis machine, having an extracorporeal blood circuit and a control unit, wherein the control unit is configured to carry out a flushing method in accordance with one of the preceding claims before the start of the treatment and/or intermittently during the treatment.

Claims

1. A method of flushing an extracorporeal blood circuit, preferably an extracorporeal blood circuit of a dialysis machine, with a flushing liquid, characterized in that the flushing liquid contains an anticoagulant agent, preferably heparin.

2. A method in accordance with claim 1, characterized in that the extracorporeal circuit is completely filled with the flushing liquid; and/or in that the flushing liquid remains stationary in the circuit for a certain dwell time and is optionally moved or is circulated in a short-circuited circuit.

3. A method in accordance with claim 2, characterized in that the dwell time amounts to between 4 and 15 minutes, preferably to between 8 and 12 minutes.

4. A method in accordance with claim 2, characterized in that the flushing liquid is displaced from the circuit at the end of the dwell time.

5. A method in accordance with claim 4, characterized in that the displacement takes place using a flushing liquid which likewise contains an anticoagulant agent, preferably heparin; or in that the displacement takes place using a flushing liquid which is free of the anticoagulant agent.

6. A method in accordance with claim 4, characterized in that the process of the remaining of the flushing liquid in the circuit and the subsequent displacement is repeated at least twice and optionally several times.

7. A method in accordance with claim 1, characterized in that at least some of the flushing liquid leaves the extracorporeal circuit through an outflow which differs from the venous port.

8. A method in accordance with claim 7, characterized in that the extracorporeal blood circuit comprises a dialyzer and the outflow corresponds to the dialyzer; or in that the outflow is arranged in the venous line.

9. A method in accordance with claim 1, characterized in that the extracorporeal blood circuit has a venous clamp and that the latter is closed at least at times during the process.

10. A method in accordance with claim 1, characterized in that the flushing liquid is admixed with the anticoagulant agent before or after its entry into the extracorporeal blood circuit.

11. A method in accordance with claim 1, characterized in that the method is carried out within the framework of the priming process.

12. An extracorporeal blood treatment unit, preferably a dialysis machine, having an extracorporeal blood circuit and a control unit, characterized in that the control unit is configured to carry out a flushing method in accordance with one of the preceding claims before the start of the treatment and/or intermittently during the treatment.

13. An extracorporeal blood treatment unit in accordance with claim 12, characterized in that the control unit is configured so that it automatically interrupts the treatment before carrying out the intermittent flushing method; and/or in that it automatically continues the treatment after carrying out the intermittent flushing method.

14. An extracorporeal blood treatment unit in accordance with claim 12, characterized in that the control unit is configured so that it activates the intermittent flushing method at periodic time intervals during the treatment, with the time intervals preferably lying between 30 minutes and 2 hours.

15. An extracorporeal blood treatment unit in accordance with claim 12, characterized in that the control unit is configured so that it takes account of the quantity of flushing liquid supplied by the method and/or of the blood drained off by the method in the determination of treatment-specific parameters, in particular in the determination of the ultrafiltration volume.

Description

[0032] Further details and advantages result from the Figures and embodiments described in the following. There are shown in the Figures:

[0033] FIG. 1: a schematic representation of fluid circuits in accordance with a dialysis machine in accordance with a first embodiment of the invention;

[0034] FIG. 2: a schematic representation of fluid circuits in accordance with a dialysis machine in accordance with a second embodiment of the invention; and

[0035] FIG. 3: a schematic representation of fluids circuits in accordance with a dialysis machine in accordance with a third embodiment of the invention.

[0036] FIG. 1 shows a schematic representation of fluid circuits in accordance with a dialysis machine in accordance with a first embodiment of the invention. The dialysis machine has a dialyzer 1 which has a blood chamber 2 and a dialyzate chamber 3 which are separated from one another by a membrane 4. The blood chamber 2 is a component of an extracorporeal blood circuit 5. The dialyzate chamber 3 is connected to an outflow 6 for dialyzate in which an ultrafiltration pump 7 is arranged. Any further lines connected to the dialyzate chamber such as a dialysis liquid source are not shown in the illustration, but can nevertheless be provided. The blood circuit 5 has an arterial line 8, with a blood pump 9, and a venous line 10 which are connected to the blood side of the dialyzer. A venous clamp 11 is located at the downstream end of the venous line.

[0037] A predilution line 12 with a substitution pump 13 opens into the arterial line downstream of the blood pump. Furthermore, a heparin pump 14 is provided which starts at the arterial line between the blood pump 9 and the predilution line. A different positioning of the predilution line and of the heparin pump is naturally also possible and covered by the invention.

[0038] A method in accordance with the invention can be carried out as follows before the start of the treatment The arterial line and the venous line are not connected to the patient. The extracorporeal blood circuit is filled completely with physiological flushing solution, for example using the predilution line or through the arterial line or venous line and the arterial line and the venous line are subsequently short-circuited. Heparin is added to the solution in the circuit using the heparin pump. The solution is subsequently circulated for 10 minutes. After the end of this method step, the short-circuit is released and the flushing solution containing heparin is displaced by fresh flushing solution, with the fresh flushing solution being able to penetrate into the circuit, for example through the predilution line or through the arterial line, and with the flushing solution containing heparin being able to be removed from the circuit, for example through the venous line. The process can optionally be repeated, i.e. the arterial and venous lines can again be short-circuited, heparin can again be injected and the solution can again be circulated.

[0039] FIG. 2 shows a schematic representation of liquid circuits in accordance with a dialysis machine in accordance with a second embodiment of the invention. Components already known from FIG. 1 are provided with corresponding reference numerals.

[0040] This embodiment differs from the embodiment shown in FIG. 1 in that the heparin pump 14 opens into the predilution line 12 and not into the arterial line. The flushing liquid can thus already be heparinized before entering into the extracorporeal blood circuit.

[0041] An example of an intermittent carrying out of the method in accordance with the invention during a dialysis treatment will be illustrated in the following with reference to this embodiment. After periodic time intervals of 90 minutes, a flushing process in accordance with the invention is carried out automatically by the control unit during the treatment. For this purpose, the substitution pump 13 is activated and the blood pump is held. The flushing liquid is heparinized before entering into the extracorporeal circuit via the line 12 by means of the heparin pump 14. As soon as the part of the extracorporeal blood circuit located downstream of the opening point of line 12 is filled with heparinized flushing liquid, the substitution pump is likewise held, the venous clamp 11 is closed and the solution is held stationary in the circuit for 10 minutes. Subsequently, the venous clamp is opened, the blood pump is activated and the treatment is continued. A long dwell time of the heparin can thus be achieved with a moderate heparin dispensing to the patient.

[0042] FIG. 3 shows a schematic representation of fluid circuits in accordance with a dialysis machine in accordance with a third embodiment of the invention. Components already known from FIGS. 1 and 2 are provided with corresponding reference numerals.

[0043] This embodiment differs from the embodiment shown in FIG. 2 in that the extracorporeal blood circuit furthermore has a separate outflow 15 for the flushing liquid. It is thus made possible that flushing liquid cannot flow off via the venous line, but rather via the separate outflow 15. At the inlet side, the separate outflow 15 has a clamp 16.

[0044] A further example of an intermitting carrying out of the method in accordance with the invention during a dialysis treatment will be illustrated in the following with reference to this embodiment. This example differs from the preceding example in that it is not the venous clamp 11 which is opened after the dwell time of the heparinized solution in the extracorporeal blood circuit, but rather the outflow clamp 16. The blood pump is then activated until the heparinized flushing solution has been displaced via the outflow 15 out of the circuit and the blood has approximately arrived in the region of the opening of the outflow. This can be detected using suitable sensors. The outflow clamp 16 is subsequently closed, the venous clamp 11 opened and the treatment continued. A long dwell time of the heparin can thus be achieved with a low heparin consumption and a heparin dispensing to the patient can be largely avoided despite a treatment-intermittent process management.

[0045] A separate outflow in the venous branch can be helpful both in the predialytic flushing and in the intradialytic flushing. The outflow is normally closed (e.g. via a clamp in a cassette system), but is automatically opened (e.g. in a pressure-controlled manner via a heparin flush control algorithm) as required. Some of the heparinized flushing solution is thus drained off. Through a suitable control, the heparinized substitution solution can thus dwell in the arterial branch, in the dialyzer and in the venous branch and can be drained off via the UF pump and the outflow. Only the heparinized substitution solution which was not removed by the UF pump and the outflow reaches the patient. The elements of the control algorithm are expanded by a possible outflow clamp. Input parameters for the control algorithm thus, for example, comprise the arterial pressure, the venous pressure and the pressure on the dialyzate side (inflow/outflow). Exemplary output parameters comprise the conveying rate of a blood pump, heparin pump, ultrafiltration pump or substitution pump as well as the control of a venous clamp, arterial clamp or outflow clamp.

[0046] In summary it can be stated that the invention provides a method and an apparatus for the fully automatic predialytic anti-clotting priming and intradialytic flushing as well as for the coagulation-inhibiting surface treatment of the extracorporeal circuit in acute and chronic renal replacement therapy, e.g. with HD or HDF methods.

[0047] Clotting in extracorporeal circuits and specifically within the framework of a low-heparin or heparin-free dialysis is reduced or prevented. An aspect of the idea relates to an automated two-phase anticoagulation without systemic liquid charging and anticoagulant charging of the patient by priming and flushing. On the one hand, a predialytic flushing of the extracorporeal circuit with heparinized solutions is therefore proposed, and an intermittent flushing of the circuit with heparinized solution with a stopped treatment, on the other hand—to counter the fatigue effect of the priming. A further aspect comprises the extracorporeal circuit being completely filled with the solution and being emptied again after a specific dwell time. A circulation can be omitted in an embodiment. A further core aspect is the automation of the process described in more detail above. In an aspect of the idea in accordance with the invention, the blood flow is greatly reduced or even stopped and the flushing volume is led off via the dialyzer or via an additional outflow so that the patient is only marginally exposed (volume from the hose piece between the outflow and the venous connection).