EXTRACORPOREAL BLOOD PUMP, HEART-LUNG MACHINE, METHOD FOR OPERATING AN EXTRACORPOREAL BLOOD PUMP, AND METHOD FOR OPERATING A HEART-LUNG MACHINE

Abstract

The present invention relates to a pulsatile positive-displacement pump with a flexible positive-displacement diaphragm which is operated pneumatically and by whose movement the blood is aspirated and displaced. A mechanical switching device in the interior of a drive unit ensures an autonomous operation of the blood pump, wherein no electricity or electronics system is needed.

Claims

1. Extracorporeal blood pump for the aspiration and displacement of blood, wherein the blood pump has two blood chambers and a mechanical driving unit, wherein the driving unit is arranged between the blood chambers, wherein a blood chamber has a membrane, a blood inlet channel and a blood outlet channel, characterized in that the blood outlet channels of both blood chambers are interconnected.

2. Extracorporeal blood pump according to claim 1, characterized in that the blood inlet channels of both blood chambers are interconnected.

3. Extracorporeal blood pump according to claim 1, characterized in that a connecting area of the blood outlet channels has a backflow check valve.

4. Extracorporeal blood pump according to claim 1, characterized in that the driving unit has a gas inlet and a gas outlet and a pressure chamber, wherein the pressure chamber is separated from a blood chamber by a membrane, the driving unit being in operative connection with the position of the membrane.

5. Extracorporeal blood pump according to claim 1, characterized in that the driving unit has two pressure chambers, wherein each pressure chamber is bordering on a blood chamber via a membrane.

6. Extracorporeal blood pump for the aspiration and displacement of blood, in particular blood pump according to claim 1, wherein the blood pump has a blood chamber and a mechanical driving unit, wherein the driving unit is bordering on the blood chamber, wherein the blood chamber has a membrane, a blood inlet channel and a blood outlet channel, wherein the driving unit has a gas inlet and a gas outlet as well as two pressure chambers, wherein each pressure chamber has an effective surface; in particular, an effective surface is a membrane, with a blood chamber being separated from a pressure chamber via a membrane, the driving unit being in operative connection with the position of the membrane.

7. Extracorporeal blood pump according to claim 1, characterized in that a blood chamber has a rotationally symmetrical portion.

8. Extracorporeal blood pump according to claim 1, characterized in that a blood inlet channel and a blood outlet channel are arranged mainly in the circumferential direction on the rotationally symmetrical portion of a blood chamber.

9. Extracorporeal blood pump according to claim 1, characterized in that a blood inlet channel has a backflow check valve.

10. Extracorporeal blood pump according to claim 1, characterized in that the driving unit has a gas inlet valve and a gas outlet valve as well as a switching device, wherein the gas inlet valve and the gas outlet valve have a closed position and an opened position with respect to a gas flow path, with the switching device having two switching end states; in particular, the switching device has exactly two switching states.

11. Extracorporeal blood pump according to claim 10, characterized in that in a switching end state for a blood chamber, the gas inlet valve is in the opened position and the gas outlet valve is in the closed position or the gas inlet valve is in the closed position and the gas outlet valve is in the opened position.

12. Extracorporeal blood pump according to claim 10, characterized in that the switching device has a magnet.

13. Extracorporeal blood pump according to claim 10, characterized in that the switching device has a lever gear.

14. Extracorporeal blood pump according to claim 10, characterized in that the switching device has a link with a spring-loaded roller.

15. Extracorporeal blood pump according to claim 1, characterized in that an area between the membranes or an area between a membrane and an effective surface has a coupling rod; in particular, the coupling rod is connected to the effective surfaces; in particular, the coupling rod is connected to a membrane and to another effective surface.

16. Extracorporeal blood pump according to claim 15, characterized in that the coupling rod has a hollow space on the inside.

17. Extracorporeal blood pump according to claim 15, characterized in that the coupling rod has a first component and a second component, the first component and the second component being connected to a spring.

18. Extracorporeal blood pump according to claim 15, characterized in that the coupling rod has a valve which is constructed so that a designated gas flow can move through the hollow space in the coupling rod and further on through the valve in the coupling rod and out of a pressure chamber via a bypass.

19. Extracorporeal blood pump according to claim 15, characterized in that the bypass has a closure device.

20. Heart-lung machine for the transport and processing of blood, the heart-lung machine having a blood inlet and a blood outlet, characterized in that the heart-lung machine has a blood pump according to claim 1.

21. Heart-lung machine according to claim 20, characterized in that the heart-lung machine has an oxygenator.

22. Heart-lung machine according to claim 20, characterized in that the heart-lung machine has a dialyzer.

23. Heart-lung machine according to claim 20, characterized in that the heart-lung machine has a filter.

24. Heart-lung machine according to claim 20, characterized in that the heart-lung machine has a gas supply, in particular an oxygen supply.

25. Method of operating an extracorporeal blood pump according to claim 1, characterized in that blood is collected from a patient, supplied to the blood pump by a blood supply and supplied back to the patient from a blood outlet of the blood pump.

26. Method according to claim 25, characterized in that in a first method step, the blood is aspirated by moving the membrane in the blood pump and by a backflow check valve in the blood inlet channel which consequently opens, wherein the blood flows into the blood chamber through the blood inlet channel, the backflow check valve at the blood inlet channel of the blood chamber closing in a second method step and the blood being displaced from the blood chamber by moving the membrane in a third method step; wherein the backflow check valve at the blood inlet channel prevents or reduces a backflow of blood through the blood inlet channel and the blood flowing out of the blood pump through the blood outlet channel.

27. Method according to claim 25, characterized in that the blood is alternately aspirated and displaced by two blood chambers; one blood chamber aspirating blood and the other blood chamber displacing blood, alternately; with the backflow check valve in the connecting area of the blood outlet channels preventing or reducing a backflow of blood into a blood chamber through a blood outlet channel.

28. Method according to claim 25, characterized in that the movement of the coupling rod acts on the membrane and influences a movement of the membrane.

29. Method according to claim 25, characterized in that the driving unit is operated with gas, wherein the gas flows into the driving unit through a gas inlet, wherein the gas flows out of the driving unit through a gas outlet; wherein a differential pressure between the blood chamber and the pressure chamber acts on the membrane and influences a movement of the membrane.

30. Method according to claim 29, characterized in that the gas flows into the driving unit through a gas inlet and subsequently into a pressure chamber through an open gas inlet valve, with the gas outlet valve of this pressure chamber being closed so that the pressure in the pressure chamber rises and influences the movement of the membrane, wherein the membrane moves in the direction of the blood chamber either directly or with time delay.

31. Method according to claim 29, characterized in that the gas flows out of a pressure chamber through a gas outlet valve and subsequently out of the driving unit through a gas outlet, with the gas inlet valve of this pressure chamber being closed so that the pressure in the pressure chamber is reduced and influences the movement of the membrane, wherein the membrane moves in the direction of the pressure chamber either directly or with time delay.

32. Method according to claim 29, characterized in that gas alternately flows into a first pressure chamber while gas flows out of a second pressure chamber and the switching device switches the gas inlet valve and the gas outlet valve when a membrane end position or an effective surface end position is reached so that subsequently, gas flows into the second pressure chamber while gas flows out of the first pressure chamber.

33. Method according to claim 32, characterized in that the switching device is switched in bistable switching states so that after a switching step, only one pressure chamber is in gas connection with the gas inlet and the other pressure chamber is in gas connection with the gas outlet.

34. Method according to claim 25, characterized in that when an amount of differential pressure between the pressure chambers is exceeded, the gas flows out of a pressure chamber via the valve.

35. Method according to claim 25, characterized in that the closure device closes the bypass so that no gas, or only a reduced flow of gas, can flow through the valve.

36. Method of operating a heart-lung machine according to claim 20, characterized in that blood is collected from a patient, is supplied to the heart-lung machine and from the heart-lung machine back to the patient.

37. Method according to claim 36, characterized in that the blood pump of the heart-lung machine is operated with a method according to one of claims 25 through 35.

38. Method according to claim 36, characterized in that the blood is supplied to the blood pump and subsequently to the oxygenator and/or the filter and/or the dialyzer.

Description

[0202] In the following, the invention will be explained in more detail by means of examples of embodiment with reference to the drawings wherein

[0203] FIG. 1 schematically shows a heart-lung machine,

[0204] FIG. 2 schematically shows a blood pump,

[0205] FIG. 3 schematically shows a switching device,

[0206] FIG. 4 schematically shows an embodiment of a coupling rod assembly with valve and bypass,

[0207] FIG. 5 schematically shows a blood pump with bypass and closure part,

[0208] FIG. 6 schematically shows a connecting portion of the blood outlet channels and

[0209] FIG. 7 schematically shows a blood chamber unit with blood inlet channel, blood outlet channel and backflow check valve.

[0210] The heart-lung machine 1 in FIG. 1 substantially consists of a blood pump 2, an oxygenator 3 and a supply unit 4.

[0211] The blood pump 2 substantially consists of a driving unit 5 and two blood chambers 6, 7.

[0212] A designated blood stream (not shown) flows in a designated blood stream inlet direction 8 in a blood inlet 9 from the patient (not shown) in the direction of the blood pump 2.

[0213] Before the designated blood stream (not shown) reaches the blood pump 2, it is divided in a flow splitter 10 and flows, downstream of the flow splitter 10, into two blood inlet channels 11, 12 into a respective blood chamber 6, 7, is pressurized therein by the driving unit 5, and leaves the blood pump 2 via a respective blood outlet channel 13, 14.

[0214] At the end of the blood outlet channels 13, 14, the designated blood streams (not shown) reconverge in a connecting area 14, and from there, the blood stream flows on downstream in the direction of the oxygenator 3.

[0215] The designated blood stream enters the oxygenator in the blood flow direction 16 and exits the oxygenator 3 in the blood flow direction 17.

[0216] Downstream of the oxygenator 3, the designated blood stream (not shown) flows back to the patient (not shown) through a blood outlet 18.

[0217] The supply unit 4 supplies the blood pump 2, in particular the driving unit 5 of the blood pump 2, with a gas flow (not shown) via a gas inlet 19 and thus supplies the blood pump 2 with the energy required for pumping the designated blood stream (not shown).

[0218] The blood pump 20 in FIG. 2 substantially consists of two blood chambers 21, 22 and a driving unit 23.

[0219] The driving unit 23 substantially consists of two pressure chambers 24, 25, a gas inlet 26, a gas outlet 27, a gas inlet valve 28, a gas outlet valve 29 and a coupling rod 30.

[0220] The coupling rod 30 has one effective surface 31, 32 each at its ends.

[0221] The blood chamber 21 is separated from the pressure chamber 24 by the effective surface 31 and the membrane 33 so that a fluid (not shown) can neither flow from the blood chamber 21 into the pressure chamber 24 nor from the pressure chamber 24 into the blood chamber 21.

[0222] The blood chamber 22 is separated from the pressure chamber 25 by the effective surface 32 and the membrane 34 so that a fluid (not shown) can neither flow from the blood chamber 22 into the pressure chamber 25 nor from the pressure chamber 25 into the blood chamber 22.

[0223] The gas inlet valve 28 can be switched such that a designated gas flow (not shown) can flow via the gas inlet 26 into the pressure chamber 24 or the pressure chamber 25.

[0224] The gas inlet valve 29 can be switched such that a designated gas flow (not shown) can flow from the pressure chamber 24 or the pressure chamber 25 into the gas outlet 27.

[0225] A designated blood stream (not shown) flows through a blood inlet channel 35 and a backflow check valve 37 into the blood chamber 21 and from there downstream via the blood outlet channel 39 and out of the blood chamber 21.

[0226] A designated blood stream (not shown) flows through a blood inlet channel 36 and a backflow check valve 38 into the blood chamber 22 and from there downstream via the blood outlet channel 40 and out of the blood chamber 22.

[0227] The blood pump 20 in FIG. 2 can for example be in the following state: a designated gas flow (not shown) moves through the gas inlet 26 into the driving unit 23 in a gas inlet direction 41. There the designated gas flow (not shown) moves into the pressure chamber 25 in the gas flow direction 42 via the gas inlet valve 28. Since the gas outlet valve 29 closes the pressure chamber 25, the gas pressure in the pressure chamber 25 increases.

[0228] The gas pressure in the pressure chamber 25 acts on the effective surface 32 and on the membrane 34 and becomes so high that the effective surface 32 and the membrane 34 move in the direction of the blood chamber 22 with the direction 43, 44 of movement.

[0229] In this way, the volume of the blood chamber 22 is reduced, the backflow check valve 38 is closed and a designated blood stream (not shown) flows toward the blood outlet channel 40 in a blood flow direction 45 and further on through the blood outlet channel 40 and out of the blood pump 20 in the blood flow direction 46.

[0230] The direction 43, 44 of movement of the effective surface 32 is transferred via the coupling rod 30 to the direction 47, 48 of movement of the effective surface 31 so that the effective surface 31 and the membrane 33 move in such a way that the volume of the blood chamber 21 increases.

[0231] In this way, a designated blood stream (not shown) is aspirated through the blood inlet channel 35 in the blood inlet direction 49 and further downstream in the blood flow direction 50 into the blood chamber 21, through the backflow check valve 37 which opens in this manner.

[0232] At the same time, the direction 47, 48 of movement of the effective surface 31 and of the membrane 33 leads to a reduction in the volume of the pressure chamber 24, causing a designated gas flow (not shown) to flow in the gas flow direction 51 through the open gas outlet valve 29 out of the pressure chamber 24 into the gas outlet 27 and to leave the driving unit 23 in the gas outlet direction 52 further downstream.

[0233] The switching device 60 in FIG. 3 substantially consists of an upper switching component 61, a lower switching component 62 and of the magnets 66, 67, 68, 69.

[0234] The upper switching component 61 and the lower switching component 62 each connect the gas inlet valve 63 and the gas outlet valve 64 at the upper and the lower end of the gas inlet valve 63 and the gas outlet valve 64.

[0235] The positions of the gas inlet valve 63 and the gas outlet valve 64 determine into which, or out of which, of the pressure chambers 71, a designated gas flow (not shown) flows; the positions are switched by the switching device 60.

[0236] The pressure chamber 71 contains the magnets 66, 69 with opposite polarization. The magnet 66 is connected to the upper switching component 61. The magnet 69 is connected to the effective surface 65 and therefore moves together with the effective surface 65. Since the effective surface 65 is connected to the effective surface 70 via the coupling rod 73, the coupling rod 73 and the effective surface 70 move along likewise.

[0237] The pressure chamber 72 contains the magnets 67, 68 with opposite polarization. The magnet 67 is connected to the lower switching component 62. The magnet 68 is connected to the effective surface 70 and therefore moves together with the effective surface 70. Since the effective surface 70 is connected to the effective surface 65 via the coupling rod 73, the coupling rod 73 and the effective surface 65 move along likewise.

[0238] The magnets 66, 69 and the magnets 67, 68 have respective opposite polarizations and therefore attract each other. The attraction force of the magnets 66, 69 and of the magnets 67, 68 depends on the distance between the respective pair of magnets. When the magnets 66, 69 or the magnets 67, 68 are in contact, their attraction force is strongest.

[0239] Due to the arrangement of the magnets 66, 67, 68, 69, in combination with the construction of the switching device 60 and the attraction force of the magnets 66, 67, 68, 69, a bistable embodiment of the switching device 60 is achieved in the kinematic of the blood pump 20 with the switching device 60 which has already been described in the explanation of FIG. 2, allowing for bistable switching states.

[0240] The embodiment of a coupling rod arrangement 80 with a valve and a bypass in FIG. 4 (the left partial figure shows the embodiment of the coupling rod arrangement 80 with closed valve 81, the right partial figure shows the embodiment of the coupling rod arrangement with open valve 81) substantially consists of a valve 81, a coupling rod 82 and a bypass 83.

[0241] The coupling rod 82 has an upper coupling rod component 84 and a lower coupling rod component 85. The upper coupling rod component 84 is fixedly connected with the effective surface 86. The lower coupling rod component 85 is fixedly connected with the effective surface 87.

[0242] The upper coupling rod component 84 and the lower coupling rod component 85 are pressed together by a spring 88 at the site of the valve 81. If a force is exerted on the effective surfaces 86, 87 which is larger than the spring force and acts in the direction opposite to the spring force, the valve 81 is opened (right partial figure).

[0243] The upper coupling rod component 84 is hollow on the inside and has bore holes 89, 90 which can connect the hollow space 91 of the upper coupling rod component 84 to the pressure chamber 92. The bore holes 89, 90 are arranged such that they release the hollow space 91 of the upper coupling rod component 84 with the pressure chamber 92 only if the latter has a volume of more than 50% of its nominal pressure chamber volume.

[0244] The lower coupling rod component 85 is also hollow on the inside and has bore holes 93, 94 which can connect the hollow space 95 of the lower coupling rod component 85 to the pressure chamber 96. The bore holes 93, 94 are arranged such that they release the hollow space 95 of the lower coupling rod component 85 with the pressure chamber 96 only if the latter has a volume of more than 50% of its nominal pressure chamber volume.

[0245] In particular, the coupling rod 82 is designed such that there is no state in which the bore holes 89, 90 connect the hollow space 91 of the upper coupling rod component 84 with the pressure chamber 92 while at the same time the bore holes 93, 94 connect the hollow space 95 of the lower coupling rod component 85 with the pressure chamber 96. In this manner, it is ensured that the hollow spaces 91, 95 of the coupling rod 82 do not compensate the pressure between the pressure chambers 92, 96.

[0246] If a force 99, 100 acts on the effective surfaces 86, 87 which is larger than the spring force and acts in the direction opposite to the spring force, the valve 81 opens (right partial figure). If the pressure chamber 96 has a volume of more than 50% of its nominal pressure chamber volume, a designated gas flow (not shown) moves from the pressure chamber 96 in the gas flow direction 97, 98 through the bore hole 93, 94 into the hollow space 95, through the open valve 81 and further downstream into the bypass 83.

[0247] Alternatively (not shown), a designated gas flow (not shown) moves from the pressure chamber 92 in the gas flow direction (not shown) through the bore holes 89, 90 into the hollow space 91, through the open valve 81 and further downstream into the bypass 83 if the force 99, 100 exerted on the effective surfaces 86, 87 is larger than the spring force, acts in the direction opposite to the spring force and the pressure chamber 92 has a volume of more than 50% of its nominal pressure chamber volume.

[0248] The blood pump 110 in FIG. 5 substantially consists of the blood chambers 111, 112 and of a driving unit 113.

[0249] Each of the blood chambers 111, 112 has a blood inlet channel (not shown) and a blood outlet channel 114, 115.

[0250] The driving unit 113 has a gas inlet 116, a gas outlet 117 and a bypass 118 so that a designated gas flow (not shown) can flow through the gas inlet 116 into the driving unit 113 in the gas inlet direction 119 and can flow out through the gas outlet 117 in the gas outlet direction 120.

[0251] If the valve 81 inside the driving unit 113 is opened, a designated gas flow (not shown) can flow out of the driving unit 113 through the bypass 118.

[0252] The bypass has a closure device 121 which makes it possible to open the bypass so that a designated gas flow (not shown) can move through the bypass when the valve 81 is opened; and to close it so that a designated gas flow (not shown) cannot move through the bypass when the valve 81 is opened; or to check it so that a designated gas flow (not shown) can only move through the bypass in a checked manner when the valve 81 is open.

[0253] The connecting area 130 in FIG. 6 (the left part and the right part show alternative blood stream paths) substantially consists of the blood outlet channels 131, 132 which meet in the connecting area 130, of the blood outlet 133 to the patient (not shown) and of a backflow check valve 134.

[0254] A designated blood stream (not shown) can flow out of the blood pump 136 through the blood outlet channel 131 in the blood flow direction 135; then, further on downstream, it encounters the connecting area 130, which is traversed in the blood flow direction 137, and the backflow check valve 134 which is traversed in the blood flow direction 137 as well. Further downstream, the designated blood stream (not shown) flows from the connecting area 130 back to the patient (not shown) through the blood outlet 133 in the blood flow direction 138.

[0255] A designated blood stream (not shown) can flow out of the blood pump 136 through the blood outlet channel 132 in the blood flow direction 139; then, further on downstream, it encounters the connecting area 130, which is traversed in the blood flow direction 140, and the backflow check valve 134 which is traversed in the blood flow direction 140 as well. Further downstream, the designated blood stream (not shown) flows from the connecting area 130 back to the patient (not shown) through the blood outlet 133 in the blood flow direction 141.

[0256] The backflow check valve 134 prevents or reduces any backflow of a designated blood stream (not shown) through the blood outlet channel 131, 132 which is not connected to the respective blood displacing blood chamber (not shown) of the blood pump 136.

[0257] A blood chamber unit 150 in FIG. 7 (the left partial figure shows the displacement of blood from the blood chamber; the right partial figure shows an aspiration of blood into the blood chamber) substantially consists of a blood chamber 151, a blood inlet channel 152, a blood outlet channel 153 and a backflow check valve 154.

[0258] When a designated blood stream (not shown) is displaced, the designated blood stream (not shown) flows out of the blood chamber 151 in the blood flow direction 115 through the blood outlet channel 153. This causes a circulation 156 of the designated blood stream (not shown) in the blood chamber 151.

[0259] When a designated blood stream (not shown) is displaced from the blood chamber 153, the backflow check valve 154 prevents or reduces a flow of the blood stream (not shown) out of the blood chamber 151 through the blood inlet channel 152.

[0260] When a designated blood stream (not shown) is aspirated, the designated blood stream (not shown) flows through the blood inlet channel 152 into the blood chamber 151 in the blood flow direction 157 and through the backflow check valve 154.

LIST OF REFERENCE NUMBERS

[0261] 1 heart-lung machine [0262] 2 blood pump [0263] 3 oxygenator [0264] 4 supply unit [0265] 5 driving unit [0266] 6 blood chamber [0267] 7 blood chamber [0268] 8 blood stream inlet direction [0269] 9 blood inlet [0270] 10 flow splitter [0271] 11 blood inlet channel [0272] 12 blood inlet channel [0273] 13 blood outlet channel [0274] 14 blood outlet channel [0275] 15 connecting area [0276] 16 blood flow direction [0277] 17 blood flow direction [0278] 18 blood outlet [0279] 19 gas inlet [0280] 20 blood pump [0281] 21 blood chamber [0282] 22 blood chamber [0283] 23 driving unit [0284] 24 pressure chamber [0285] 25 pressure chamber [0286] 26 gas inlet [0287] 27 gas outlet [0288] 28 gas inlet valve [0289] 29 gas outlet valve [0290] 30 coupling rod [0291] 31 effective surface [0292] 32 effective surface [0293] 33 membrane [0294] 34 membrane [0295] 35 blood inlet channel [0296] 36 blood inlet channel [0297] 37 backflow check valve [0298] 38 backflow check valve [0299] 39 blood outlet channel [0300] 40 blood outlet channel [0301] 41 gas inlet direction [0302] 42 gas flow direction [0303] 43 direction of movement [0304] 44 direction of movement [0305] 45 blood flow direction [0306] 46 blood flow direction [0307] 47 direction of movement [0308] 48 direction of movement [0309] 49 blood inlet direction [0310] 50 blood flow direction [0311] 51 gas flow direction [0312] 52 gas outlet direction [0313] 60 switching device [0314] 61 upper switching component [0315] 62 lower switching component [0316] 63 gas inlet valve [0317] 64 gas outlet valve [0318] 65 effective surface [0319] 66 magnet [0320] 67 magnet [0321] 68 magnet [0322] 69 magnet [0323] 70 effective surface [0324] 71 pressure chamber [0325] 72 pressure chamber [0326] 73 coupling rod [0327] 80 coupling rod arrangement [0328] 81 valve [0329] 82 coupling rod [0330] 83 bypass [0331] 84 upper coupling rod component [0332] 85 lower coupling rod component [0333] 86 effective surface [0334] 87 effective surface [0335] 88 spring [0336] 89 bore hole [0337] 90 bore hole [0338] 91 hollow space [0339] 92 pressure chamber [0340] 93 bore hole [0341] 94 bore hole [0342] 95 hollow space [0343] 96 pressure chamber [0344] 97 gas flow direction [0345] 98 gas flow direction [0346] 99 force [0347] 100 force [0348] 110 blood pump [0349] 111 blood chamber [0350] 112 blood chamber [0351] 113 driving unit [0352] 114 blood outlet channel [0353] 115 blood outlet channel [0354] 116 gas inlet [0355] 117 gas outlet [0356] 118 bypass [0357] 119 gas inlet direction [0358] 120 gas outlet direction [0359] 121 closure device [0360] 130 connecting area [0361] 131 blood outlet channel [0362] 132 blood outlet channel [0363] 133 blood outlet [0364] 134 backflow check valve [0365] 135 blood flow direction [0366] 136 blood pump [0367] 137 blood flow direction [0368] 138 blood flow direction [0369] 139 blood flow direction [0370] 140 blood flow direction [0371] 141 blood flow direction [0372] 150 blood chamber unit [0373] 151 blood chamber [0374] 152 blood inlet channel [0375] 153 blood outlet channel [0376] 154 backflow check valve [0377] 155 blood flow direction [0378] 156 circulation [0379] 157 blood flow direction