Extracorporeal Blood Treatment Device for Operation with a Single Patient Connection and Method for Operation of an Extracorporeal Blood Treatment Device with a Single Patient Connection

Abstract

An extracorporeal blood treatment device for operation with a single patient connection, connected by an arterial and a venous blood line to an extracorporeal blood circuit, and a method for operating a blood treatment device with a single patient connection. The blood treatment device has two apparatuses for conveying blood in the arterial and venous blood lines. The second apparatus for conveying blood comprises means for collecting blood and means for establishing a pressure in the means for collecting blood, so that blood collected in the means for collecting blood flows to the patient connection. Furthermore, the blood treatment device has arterial and venous closure elements for interrupting the flow of liquid in the arterial and venous blood lines, as well as a control unit for actuating the two apparatuses for conveying blood and the arterial and venous closure elements. The blood treatment device and the method for operating are characterized in that the first apparatus for conveying blood is operated both during the arterial and venous phases, so that blood flows continuously through the blood treatment unit.

Claims

1. An extracorporeal blood treatment device for operation with a single patient connection, which is connected to an arterial and a venous blood line of an extracorporeal blood circuit, the blood treatment device comprising: a first apparatus for conveying blood; a second apparatus for conveying blood comprising a means for collecting blood that flows in the venous blood line from a blood treatment unit, and a means for establishing a pressure in the means for collecting blood, such that blood collected in the means for collecting blood flows to the single patient connection; an arterial closure element for interrupting the flow of liquid in the arterial blood line; a venous closure element for interrupting the flow of liquid in the venous blood line; and a control unit for actuating the first and second apparatuses for conveying blood, and for actuating the arterial and venous closure elements; wherein the control unit is configured to actuate the first apparatus for conveying blood, the means for establishing a pressure in the means for collecting blood, the arterial closure element, and the venous closure element such that in an arterial phase, the first apparatus for conveying blood is operated with an open arterial closure element and a closed venous closure element at a predetermined first delivery rate, such that blood flows at a predetermined first flow rate (Q.sub.(1)a from the single patient connection via the blood treatment unit into the means for collecting blood, in a venous phase following the arterial phase, the first apparatus for conveying blood is operated with an open arterial closure element and an open venous closure element at a predetermined second delivery rate, such that blood flows at a predetermined second flow rate (Q.sub.(1)v) from the single patient connection via the blood treatment unit into the means for collecting blood, and in the venous phase, a pressure is established in the means for collecting blood with the means for establishing a pressure in the means for collecting blood, such that blood flows at a predetermined third flow rate from the means for collecting blood to the single patient connection; wherein there is continuous switching between the arterial phase and the venous phase.

2. The blood treatment device according to claim 1, wherein the predetermined first flow rate (Q.sub.(1)a) is equal to the predetermined second flow rate (Q.sub.(1)v).

3. The blood treatment device according to claim 1, wherein the predetermined first flow rate (Q.sub.(1)a) is greater than or less than the predetermined second flow rate (Q.sub.(1)v).

4. The blood treatment device according to claim 1, wherein the single patient connection is configured as a cannula with a distal end and a proximal end, wherein a connection piece connecting the arterial and venous blood lines is provided at the proximal end of the cannula.

5. The blood treatment device according to claim 2, wherein the single patient connection is configured as a cannula with a distal end and a proximal end, wherein a connection piece connecting the arterial and venous blood lines is provided at the proximal end of the cannula.

6. The blood treatment device according to claim 1, wherein the first apparatus for conveying blood is configured as an occluding blood pump.

7. The blood treatment device according to claim 4, wherein the first apparatus for conveying blood is configured as an occluding blood pump.

8. The blood treatment device according to claim 1, wherein the second apparatus for conveying blood further comprises a means for storing air, which comprises a closed volume, wherein the means for establishing a pressure are in flow connection with the means for storing air and the means for collecting blood, such that air can be transferred from the means for storing air into the means for collecting blood while displacing the blood collected in the means for collecting blood.

9. The blood treatment device according to claim 4, wherein the second apparatus for conveying blood further comprises a means for storing air, which comprises a closed volume, wherein the means for establishing a pressure are in flow connection with the means for storing air and the means for collecting blood, such that air can be transferred from the means for storing air into the means for collecting blood while displacing the blood collected in the means for collecting blood.

10. The blood treatment device according to claim 8, wherein the second apparatus for conveying blood further comprises a bypass line connecting the means for storing air and the means for collecting blood, wherein a bypass valve is positioned in the bypass line.

11. The blood treatment device according to claim 9, wherein the second apparatus for conveying blood further comprises a bypass line connecting the means for storing air and the means for collecting blood, wherein a bypass valve is positioned in the bypass line.

12. A method for operating an extracorporeal blood treatment device with a single patient connection, which is connected to an arterial blood line and a venous blood line of an extracorporeal blood circuit, the method comprising the following steps: in an arterial phase, conveying blood at a predetermined first flow rate (Q.sub.(1)a) from the single patient connection via a blood treatment unit into a means for collecting blood, wherein the flow of liquid to the patient connection is interrupted; in a venous phase following the arterial phase, conveying blood at a predetermined second flow rate (Q.sub.(1)v) from the single patient connection via the blood treatment unit into the means for collecting blood; and establishing a pressure in the means for collecting blood, such that blood flows at a predetermined third flow rate from the means for collecting blood to the single patient connection; wherein there is continuous switching between the arterial phase and the venous phase.

13. The method according to claim 12, wherein the predetermined first flow rate (Q.sub.(1)a) is equal to the predetermined second flow rate (Q(.sub.(1)v).

14. The method according to claim 12, wherein the predetermined first flow rate (Q.sub.(1)a) is greater than or less than the predetermined second flow rate (Q.sub.(1)v).

15. The method according to claim 12, wherein the blood is conveyed by an occluding blood pump from the single patient connection via the blood treatment unit into the means for collecting blood.

16. The method according to claim 13, wherein the blood is conveyed by an occluding blood pump from the single patient connection via the blood treatment unit into the means for collecting blood.

17. The method according to claim 14, wherein the blood is conveyed by an occluding blood pump from the single patient connection via the blood treatment unit into the means for collecting blood.

18. The method according to claim 12, wherein, while establishing a pressure in the means for collecting blood, air is transferred from a means for storing air into the means for collecting blood, while displacing blood collected in the means for collecting blood.

19. The method according to claim 13, wherein, while establishing a pressure in the means for collecting blood, air is transferred from a means for storing air into the means for collecting blood, while displacing blood collected in the means for collecting blood.

20. The method according to claim 15, wherein, while establishing a pressure in the means for collecting blood, air is transferred from a means for storing air into the means for collecting blood, while displacing blood collected in the means for collecting blood.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 shows the components of the extracorporeal blood treatment device for single needle operation in accordance with the present invention in a much simplified schematic representation.

[0033] FIG. 2 shows the element 10 of FIG. 1 in enlarged representation.

DETAILED DESCRIPTION

[0034] FIG. 1 shows the components of the blood treatment device for single needle operation, in particular a dialysis device, in a much simplified schematic representation. The individual components of the blood treatment device are described in detail in WO 2008/148506 A2, which is incorporated herein in its entirety by reference thereto.

[0035] The blood treatment device comprises an extracorporeal blood circuit 1 with a blood treatment unit 2, for example, a dialysis machine. The dialysis machine 2 is subdivided by a semipermeable membrane 3 into a blood chamber 4 and a dialysis fluid chamber 5. The blood of the patient is conveyed in the extracorporeal blood circuit 1 by means of a first apparatus 6 for conveying blood and a second apparatus 7 for conveying blood. The first apparatus 6 for conveying blood is preferably an occluding tube pump. The dialysis fluid circuit is not shown in FIG. 1.

[0036] A tube set is inserted in the blood treatment device and is discarded after the treatment. The tube set comprises an arterial blood supply line 8, which is inserted in the occluding tube pump 6, leading to the inlet 4A of the blood chamber 4 of the dialysis machine 2, and a venous blood return line leading from the outlet 4B of the blood chamber 4. Blood supply line and blood return line 8, 9 are attached to a common patient connection 10. The patient connection 10 is a cannula with a distal and a proximal end 10A, 10B. The proximal end 10B of the cannula 10 is configured as a connection piece 10C, to which the blood supply and return lines 8, 9 are attached (FIG. 2).

[0037] The second apparatus 7 for conveying blood comprises means 11 for collecting blood in which the blood return line 9 is positioned. The means 11 for collecting blood are configured as a vessel with a predetermined, closed volume. In the following, the means for collecting blood are described as blood collecting vessel 11.

[0038] Upstream of the blood pump 6 is an arterial closure element 12A in the blood supply line 8 for interrupting the blood supply line 8 and, downstream of the blood collecting vessel 11, a venous closure element 12B is positioned in the blood return line 9 for interrupting the blood return line. The closure elements 12A, 12B can be, for example, electromagnetically or pneumatically actuated tube clamps.

[0039] The blood collecting vessel 11 has an inlet 13, to which a first segment 9A of the blood return line 9 leads, and has an outlet 14, from which a second segment 9B of the blood return line 9 leaves. The level sensor 15 is provided to detect a specific filling level in the blood collecting vessel 11, to detect when the filling level in the blood collecting vessel has reached a predetermined value. Further, a pressure sensor 16 is provided to measure the pressure in the blood collecting vessel 11.

[0040] When the blood collecting vessel 11 is filled with blood, a certain volume of air remains above the liquid level 17 in the blood collecting vessel. The blood collecting vessel 11 has a flow connection with means 18 for storing gas, in particular air, which is configured as a vessel with a closed volume. In the following, the means 18 for storing gas is described as air reservoir.

[0041] So that the blood collecting vessel 11 and the air reservoir 18 can communicate with each other, a line 19 proceeds from the top of the blood collecting vessel, leading to the air reservoir 18. Means 20 for establishing a pressure in the blood collection chamber 11, which can be configured as a conventional compressor, for example, are positioned in the line 19. As long as the compressor 20 is not operated, the compressor interrupts the flow connection between the blood collecting vessel 11 and the air reservoir 18. During operation of the compressor 20, however, air in the air reservoir 18 is transferred into the blood collecting vessel 11. Since the air is compressed, a predetermined pressure is built up in the blood collecting vessel 11. The pressure is kept substantially constant by means of the regulated compressor 20.

[0042] The line 19 comprises two line segments 19A, 19B, of which the one line segment 19A connects the blood collecting vessel 11 to the pressure-side connection 20A of the compressor 20 and the other line segment 19B connects the suction-side connection 20B of the compressor 20 to the air reservoir 18. These line segments 19A, 19B form a connecting line 19 for transferring air from the air reservoir to the blood collecting vessel.

[0043] A bypass line 21 is provided to allow transfer of air from the blood collecting vessel 11 to the air reservoir 18 when the compressor 20 is not in operation, proceeding from the first line segment 19A of the line 19 and leading to the second line segment 19B of the line 19. A bypass valve 22 is connected into the bypass line 21. Together with the corresponding line segments of the line 19, the bypass line 21 forms a connecting line for conveying air from the blood collecting vessel 11 to the air reservoir 18.

[0044] In order to prevent fluid from passing out of the blood collecting vessel 11 into the air reservoir 18, a filter 23 is positioned in the first line segment 19A of the line 19, containing a hydrophobic, impermeable membrane, i.e., permeable to air, but impermeable to liquid.

[0045] To supply air to and remove air from the closed volume, which comprises the blood collecting vessel 11 and the air reservoir 18, together with the line 19, means 24 are provided for supplying and removing air, which comprises an air supply/removal line 24A connected to the first line segment 19A of the line 19 with an air supply/removal valve 24B.

[0046] Apart from the pressure sensor 16 for measuring the pressure in the blood collecting vessel 11, a pressure sensor 25 is provided for measuring the pressure in the first line segment 19A of the line 19 between the filter 23 and the compressor 20, and a further pressure sensor 26 is provided for measuring the pressure in the air reservoir 18.

[0047] The blood treatment device can have in addition a substituate supply for a pre- or post-dilution from a substituate source (not shown) via a substituate line (not shown), which can be attached to the arterial blood line 8 upstream of the blood treatment unit 2 or the venous blood line 9 downstream of the blood treatment unit 2.

[0048] The blood treatment device has a central control unit 27, which is connected by electrical lines (not shown) to the blood pump 6, the arterial and venous tube clamps 12A, 12B, the bypass valve 22, the air supply/removal valve 24B, the level sensor 15, the compressor 20, and the pressure sensors 16, 25 and 26.

[0049] The operation of the dialysis device is described in detail in the following. The central control unit 27 controls the individual components of the blood treatment device as follows.

[0050] The pressure in the blood collecting vessel 11 is referred to in the following as chamber pressure and the pressure in the air reservoir 18 as reservoir pressure.

[0051] At the start of the actual dialysis treatment, the system is initialized, as described in WO 2008/148506 A2. During the operation of the blood treatment device, the control unit 27 successively switches between an arterial and a venous phase, wherein the blood pump 6 is operated in both the arterial and the venous phases.

[0052] At the start of the arterial phase, the control unit 27 opens the arterial closure element 12A and closes the venous closure element 12B. The blood pump 6 is operated in the arterial phase at a predetermined delivery rate, so that blood is conveyed in the blood supply line 8 from the patient connection 10 at a predetermined flow rate Q.sub.(1)a into the blood collecting vessel 11. The volume of blood conveyed by the blood pump 6 is removed directly from the patient. For example, the blood pump conveys blood at a flow rate of 300 ml/min. Consequently, the blood collecting vessel 11 is filled with blood. While this is proceeding, an undesired recirculation cannot occur, since the venous closure element 12B is closed. The compressor 20 stops in the arterial phase.

[0053] The bypass valve 22 is opened by the control unit 27 in the arterial phase, so that the air displaced from the blood collecting vessel 11 passes via the bypass line 21 into the air reservoir 18. Consequently, the reservoir pressure rises. The bypass valve 22 is particularly preferred to be a digital valve that is unregulated in the open state. Such a digital valve is particularly cost-effective. The digital valve is operated in a cyclic manner, to keep pressure fluctuations small. Cycling of the opening period of the valve can particularly preferably take place at a frequency of 1 Hz to 6 Hz. Alternatively, it is also possible to use a proportional valve, though this incurs higher costs.

[0054] As soon as the mass of air contained in the blood collecting vessel 11 and the line volume has reached a predetermined amount, which is calculated from the desired stroke volume and the desired return pressure, the control unit 27 closes the bypass valve 22. As a result, two separate volumes of air are formed, i.e., the volume of air in the blood collecting vessel 11 with the associated line segments and the volume of the air reservoir 18 with the associated line segments.

[0055] In the venous phase, the arterial closure element 12A is opened and the bypass valve 22 is closed. The control unit 27 opens the venous closure element 12B in the venous phase. The blood pump 6 is operated in the venous phase at a delivery rate Q.sub.(1)v, which can be the same as the delivery rate of the blood pump in the arterial phase Q.sub.(1)v=Q.sub.(1)a, for example 300 ml/min. However, the delivery rate of the blood pump 6 in the venous phase can also be greater or smaller than the delivery rate in the arterial phase.

[0056] The compressor 20 is operated at the venous phase and conveys air from the air reservoir 18 into the blood collecting vessel 11, in order to establish a pressure, so that blood is conveyed from the blood collecting vessel. In doing so, the compressor 20 is operated so that the desired return pressure is produced in the blood collecting vessel 11. Specification of a return pressure defines a corresponding blood flow rate. The return pressure is specified so that the set blood flow rate corresponds to the target value. Thus, the return pressure is regulated in order to set the corresponding flow rate. Since the air is continuously supplied to the blood collecting vessel 11 from the air reservoir 18, the reservoir pressure continuously decreases.

[0057] Due to the simultaneous operation of the blood pump 6 and the compressor 20 in the venous phase, a blood flow rate is produced in the blood return line 9 downstream of the blood collecting vessel 11, resulting from the total of the volume of blood Q.sub.(1)v conveyed by the blood pump 6 and the volume of blood Q.sub.(2)v displaced from the blood collecting vessel 11. Since the blood pump 6 is also operated during the venous phase, the flows Q.sub.(1)v and Q.sub.(2)v split again at the patient connection 10. Thus, it is solely the rate at which the level drops in the blood collecting container 11 that determined the venous return flow Q.sub.(2)v into the patient. This return flow Q.sub.(2)v is independent of the circulation flow Q.sub.(1)v, which is set in the closed circuit, which comprises the arterial and venous blood lines 8, 9 and the blood chamber 4 of the dialyser 2. Due to the continuous operation of the blood pump 6 in the venous and arterial phases, blood flows continuously through the blood chamber 4 of the dialyser 2. Dialysis fluid always flows continuously through the dialysis fluid chamber 5.

[0058] In the present exemplary embodiment, the compressor 20 is operated so that the return pressure required for setting the desired blood flow is established. At the same time, the compressor 20 is so regulated that the return pressure is essentially constant, thus resulting in an essentially constant blood flow.

[0059] An alternative exemplary embodiment of the present invention does not provide regulation of the return pressure, but regulates the volume flow in the blood collecting vessel 11 so that the corresponding return pressure is set in the blood collecting vessel 11. In an alternative exemplary embodiment, analogous to a level measurement, the pressure is measured in the blood collecting vessel 11 with the pressure sensor 16 at two points in time. The measurement of pressure, in each case at two points in time, can be made continuously over the whole period of treatment. The variation of the volume of blood in the blood collecting vessel 11 can be calculated from the two pressure measurements for the two points in time from the change of volume per unit time of the volume flow rate.

[0060] This calculation can be carried out continuously during the treatment. The speed of the compressor 20 is regulated, so that the calculated volume flow rate corresponds to the predetermined target flow rate. The return pressure is thus adjusted in this exemplary embodiment on the basis of compressor speed.