BLOOD CIRCULATION SYSTEM

In a blood circulation system (10), a first blood circulation device (12) includes a first detection unit (22) that detects a first flow rate of blood flowing through a first blood sending vessel portion (28). A second blood circulation device (14) includes a second detection unit (95) that detects a second flow rate of blood flowing through a blood sending cannula (110). A first control section (74) controls a first centrifugal pump (20) based on a detection result of the second detection unit (95). A second control section (154) controls a second centrifugal pump (92) based on a detection result of the first detection unit (22).

BACKGROUND OF THE INVENTION

The present invention relates to a blood circulation system.

Prashant Rao, Zain Khalpey, Richard Smith, Daniel Burkhoff, Robb D. Kociol, Venoarterial Extracorporeal Membrane Oxygenation for Cardiogenic Shock and Cardiac Arrest Cardinal Considerations for Initiation and Management [Circ Heart Fail.2018; 11:e004905. DOI: 10.1161/CIRCHEARTFAILURE.118.004905] discloses a blood circulation system including a first blood circulation device and a second blood circulation device.

One type of blood circulation device is called Impella®, available from Abiomed of Danvers, Massachusetts, which is placed percutaneously to assist the function of the heart of a patient. That is, the first type of blood circulation device is a catheter inserted into the femoral artery. A distal end of the catheter is inserted into the left ventricle via the femoral artery and the ascending aorta. A first opening is formed at the distal end of the catheter. A second opening is formed at a position of the ascending aorta in the catheter. An axial flow pump is provided in the catheter between the first opening and the second opening. The axial flow pump removes blood from the left ventricle via the first opening and delivers the blood to the ascending aorta via the second opening.

A second type of blood circulation device is called “V-A ECMO” (venoarterial extracorporeal membrane oxygenation) which substitutes for the functions of the heart and lungs of the patient. That is, the second type of blood circulation device includes a blood circulation circuit, a centrifugal pump, and an oxygenator. The centrifugal pump and the oxygenator are disposed in the blood circulation circuit. The centrifugal pump aspirates blood from the patient's femoral vein and sends it to the oxygenator. The oxygenator oxygenates the blood. The oxygenated blood is delivered to the femoral artery of the patient.

In a case where only the second type of blood circulation device is used, the burden on the patient's heart increases. On the other hand, when the first type of blood circulation device and the second blood circulation device are used in combination, the burden on the heart of the patient is reduced, and a survival rate of the patient is improved.

The condition of the patient changes over time. In a case where the first type of blood circulation device and the second type of blood circulation device are used in combination, it is necessary to appropriately adjust the flow rates of blood in the first blood circulation device and the second blood circulation device according to the condition of the patient. Note that the flow rate of blood in the first blood circulation device is an amount of blood (blood removal amount) sucked from the left ventricle through the first opening. The blood removal amount is also referred to as an unloading flow rate. The unloading flow rate is also an amount of blood (a blood sending amount) sent from the axial flow pump to the ascending aorta via the second opening.

However, in the first (percutaneous) blood circulation device, since the axial flow pump is built in the catheter, the flow rate (unloading flow rate) of the axial flow pump cannot be directly measured. Furthermore, the axial flow pump has a pump characteristic in which the unloading flow rate sharply changes due to a pressure difference between an inlet and an outlet of the axial flow pump. Therefore, the unloading flow rate cannot be accurately calculated based on a rotation speed of the axial flow pump and a current flowing through a motor that drives the axial flow pump. As a result, the axial flow pump cannot be appropriately controlled based on the calculated unloading flow rate. Therefore, the unloading flow rate cannot be appropriately adjusted according to the condition of the patient.

Furthermore, also in the second blood circulation device, it is necessary to appropriately control the blood sending amount to the patient. However, since the first blood circulation device and the second blood circulation device are used in combination, it is difficult to appropriately control the blood sending amount. As a result, the burden on the medical worker increases.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a blood circulation system capable of appropriately controlling a flow rate of blood according to the condition of a patient.

A first aspect of the present invention is a blood circulation system that removes blood from a living body and sends the blood to the living body, the blood circulation system including: a first blood circulation device; and a second blood circulation device, wherein the first blood circulation device includes: a first blood removal vessel portion having a distal end inserted into a left ventricle of the living body via a subclavian artery of the living body; a first blood sending vessel portion having a distal end inserted into an ascending aorta of the living body via the subclavian artery; a first centrifugal pump that is disposed outside the living body, includes a first inlet port and a first outlet port, removes blood from the left ventricle to the first inlet port via the first blood removal vessel portion, and sends blood from the first outlet port to the ascending aorta via the first blood sending vessel portion, the first inlet port being connected to a proximal end of the first blood removal vessel portion, the first outlet port being connected to a proximal end of the first blood sending vessel portion; and a first control section that controls the first centrifugal pump, and wherein the second blood circulation device includes: a second blood removal vessel portion having a distal end inserted into a femoral vein of the living body; a second blood sending vessel portion having a distal end inserted into a femoral artery of the living body; a second centrifugal pump that is disposed outside the living body, includes a second inlet port and a second outlet port, removes blood from the femoral vein to the second inlet port via the second blood removal vessel portion, and sends blood from the second outlet port to the femoral artery via the second blood sending vessel portion, the second inlet port being connected to a proximal end of the second blood removal vessel portion, the second outlet port being connected to a proximal end of the second blood sending vessel portion; a second control section that controls the second centrifugal pump; and a detection unit that is disposed outside the living body and detects a flow rate of blood flowing through the second blood sending vessel portion, and the first control section controls the first centrifugal pump based on a detection result of the detection unit that detects the flow rate of blood flowing from the second centrifugal pump through the second blood sending vessel portion.

According to the present invention, the centrifugal pump of one of the blood circulation devices can be controlled based on the detection result of a flow rate detection unit provided in the other one of the blood circulation devices. As a result, the flow rate of the blood flowing through each blood circulation device can be appropriately controlled according to the condition of a patient.

In the above blood circulation system, it is preferable that the first blood circulation device further includes a flow rate calculation unit that calculates a flow rate of blood flowing into the first blood sending vessel portion from a target flow rate flowing from the first blood circulation device and the second blood circulation device to the ascending aorta and a detection result of the detection unit, and the first control section controls a rotation speed of the first centrifugal pump based on the flow rate calculated by the flow rate calculation unit.

This makes it possible to accurately control the flow rate of the blood flowing through the other blood circulation device while considering the state of one blood circulation device.

A second aspect of the present invention is a blood circulation system that removes blood from a living body and sends the blood to the living body, the blood circulation system including: a first blood circulation device and a second blood circulation device, wherein the first blood circulation device includes: a first blood removal vessel portion having a distal end inserted into a left ventricle of the living body via a subclavian artery of the living body; a first blood sending vessel portion having a distal end inserted into an ascending aorta of the living body via the subclavian artery; a first centrifugal pump that is disposed outside the living body, includes a first inlet port and a first outlet port, removes blood from the left ventricle to the first inlet port via the first blood removal vessel portion, and sends blood from the first outlet port to the ascending aorta via the first blood sending vessel portion, the first inlet port being connected to a proximal end of the first blood removal vessel portion, the first outlet port being connected to a proximal end of the first blood sending vessel portion; a first control section that controls the first centrifugal pump; and a detection unit that is disposed outside the living body and detects a flow rate of blood flowing through the first blood sending vessel portion, wherein the second blood circulation device includes: a second blood removal vessel portion having a distal end inserted into a femoral vein of the living body; a second blood sending vessel portion having a distal end inserted into a femoral artery of the living body; a second centrifugal pump that is disposed outside the living body, includes a second inlet port and a second outlet port, removes blood from the femoral vein to the second inlet port via the second blood removal vessel portion, and sends blood from the second outlet port to the femoral artery via the second blood sending vessel portion, the second inlet port being connected to a proximal end of the second blood removal vessel portion, the second outlet port being connected to a proximal end of the second blood sending vessel portion; and a second control section that controls the second centrifugal pump; wherein the second control section controls the second centrifugal pump based on a detection result of the detection unit which detects the flow rate of blood flowing from the first centrifugal pump through the first blood sending vessel portion.

According to the present invention, the centrifugal pump of one of the blood circulation devices can be controlled based on the detection result of the detection unit provided in the other one of blood circulation devices. As a result, the flow rate of the blood flowing through each blood circulation device can be appropriately controlled according to the condition of a patient.

In the blood circulation system, it is preferable that the second blood circulation device further includes a flow rate calculation unit that calculates a flow rate of blood flowing into the second blood sending vessel portion from a target flow rate flowing from the first blood circulation device and the second blood circulation device to the ascending aorta and a detection result of the detection unit, and the second control section controls a rotation speed of the second centrifugal pump based on the flow rate calculated by the flow rate calculation unit.

This makes it possible to accurately control the flow rate of the blood flowing through the other blood circulation device while considering the state of one blood circulation device.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As illustrated inFIG.1, a blood circulation system10according to the present embodiment includes a first blood circulation device12and a second blood circulation device14.

The first blood circulation device12includes a first blood circulation circuit18that removes blood from a patient16(living body) and sends the blood to the patient16. The first blood circulation circuit18forms a path for extracorporeally circulating blood by sucking blood from the patient16and returning the blood to the patient16again. The first blood circulation device12further includes a first centrifugal pump20, a first detection unit22, and a first control unit24. The first centrifugal pump20is disposed in the first blood circulation circuit18. The first centrifugal pump20assists a heart function of the patient16. The first blood circulation device12circulates the blood of the first blood circulation circuit18by driving the first centrifugal pump20.

The first blood circulation circuit18includes a first blood removal vessel portion26, a first blood sending vessel portion28, a first blood removal tube30, and a first blood sending tube32. In the first blood circulation circuit18, the first blood removal vessel portion26, the first blood removal tube30, the first blood sending tube32, and the first blood sending vessel portion28are disposed in this order along a direction in which blood circulates. The first blood removal vessel portion26and the first blood sending vessel portion28constitute one cannula34illustrated inFIGS.1and2. That is, the cannula34is a tubular body having two hollow portions. One of the two hollow portions serves as the first blood removal vessel portion26, and the other hollow portion serves as the first blood sending vessel portion28.

A distal end of the cannula34is inserted into a left ventricle42of a heart40via a subclavian artery36and an ascending aorta38of the patient16. A first opening44communicating with the first blood removal vessel portion26is formed at the distal end of the cannula34. That is, a distal end of the first blood removal vessel portion26is inserted into the left ventricle42. A second opening46communicating with the first blood sending vessel portion28is formed at a position of the ascending aorta38in the cannula34. That is, the distal end of the first blood removal vessel portion26is inserted into the ascending aorta38. Note that an arrow inFIG.2indicates the flow of blood in a case where the heart40of the patient16is normal.

As illustrated inFIG.1, a proximal end of the cannula34is bifurcated into two portions. One branch portion is a proximal end of the first blood removal vessel portion26. The proximal end of the first blood removal vessel portion26is connected to a first inlet port48of the first centrifugal pump20via the first blood removal tube30. The other branch portion is a proximal end of the first blood sending vessel portion28. The proximal end of the first blood sending vessel portion28is connected to a first outlet port50of the first centrifugal pump20via the first blood sending tube32. Note that, in the present embodiment, as illustrated inFIG.1, a type in which the proximal end of the cannula34is branched into two portions is illustrated. In the present embodiment, it is also possible to use two independent cannulae.

The first blood removal vessel portion26, the first blood removal tube30, and the first inlet port48constitute a first blood removal line52for removing blood from the patient16. The first outlet port50, the first blood sending tube32, and the first blood sending vessel portion28constitute a first blood sending line54for sending blood to the patient16.

The first centrifugal pump20functions as a power source for removing blood from the patient16to the outside of the body. Furthermore, the first centrifugal pump20functions as a power source for sending blood into the body of the patient16. The first centrifugal pump20includes a first impeller56and a first pump housing58that accommodates the first impeller56. The first centrifugal pump20causes the blood to flow by a centrifugal force accompanying the rotation of the first impeller56. That is, the first centrifugal pump20aspirates the blood of the patient16via the first blood removal line52by negative pressure. Furthermore, the first centrifugal pump20sends blood to the patient16through the first blood sending line54. The first pump housing58is formed of a resin material or the like. The first pump housing58is a hollow cylinder.

The first centrifugal pump20is detachably connected to a first drive device60. The first drive device60includes a first motor62and a first motor housing64that accommodates the first motor62. The first pump housing58and the first motor housing64are detachably connected.

The first impeller56is disposed in an internal space of the first pump housing58. The first impeller56and the first motor62are magnetically coupled via a magnetic coupling portion (not illustrated). Therefore, the first impeller56is rotated by the drive of the first motor62.

The first inlet port48is provided in the first pump housing58. A hollow portion (flow path) of the first inlet port48communicates with the internal space of the first pump housing58. The first inlet port48is formed at a position opposite to a position where the first motor housing64is mounted in the first pump housing58. The first inlet port48is provided on an axis of the first impeller56. The first inlet port48protrudes from the first pump housing58in an axial direction of the first impeller56.

The first pump housing58is further provided with the first outlet port50communicating with the internal space of the first pump housing58. The first outlet port50protrudes from a side wall66of the first pump housing58in a direction intersecting the axis of the first impeller56.

The first centrifugal pump20maybe a volute pump. Furthermore, the first centrifugal pump20maybe an open-type pump. In a case where the first centrifugal pump20is an open-type pump, the first impeller56is not provided with a cover that covers a plurality of blades.

The first detection unit22is disposed outside the body of the patient16. Specifically, the first detection unit22is disposed in the middle of the first blood sending tube32. The first detection unit22is a flow rate sensor that detects a flow rate (first flow rate) of blood flowing through the first blood sending line54. The first detection unit22successively detects the first flow rate and outputs the detection results to the first control unit24.

The first control unit24includes a first input section70, a first setting section72(flow rate calculation unit), a first control section74, a first display section76, and a first communication section78. The first control unit24is a controller including the first display section76that is a display. The first control unit24controls the first blood circulation device12as a whole by reading and executing a program stored in a memory (not illustrated).

The first input section70is an operator operable by a user. The first input section70is, for example, a touch panel. A user such as a medical worker operates the first input section70to input a target flow rate for the blood circulation system10to flow into the ascending aorta38. The target flow rate is also a flow rate of blood required by the patient16.

The first setting section72sets a target value (first target value) of the first flow rate based on the target flow rate or the like. For example, in the blood circulation system10, in a case where only the first blood circulation device12operates, the first setting section72sets the target flow rate to the first target value. Note that the target flow rate may change with the lapse of time according to the condition of the patient16. Furthermore, the first target value may change with the lapse of time according to the condition of the patient16.

The first control section74controls a rotation speed of the first motor62based on the first target value set by the first setting section72.

Here, setting processing in the first setting section72and control processing of the rotation speed of the first motor62in the first control section74will be described in detail.

In order to remove blood from the left ventricle42and send the blood to the ascending aorta38, it is necessary to adjust a pressure difference between the left ventricle42and the ascending aorta38to an appropriate value. Specifically, the pressure of the ascending aorta38needs to be higher than the pressure of the left ventricle42.

Therefore, the first control section74appropriately adjusts the pressure difference between the left ventricle42and the ascending aorta38by controlling the rotation speed of the first centrifugal pump20. Note that a rotation speed N of the first centrifugal pump20is also a rotation speed of the first impeller56.

FIG.3illustrates pump characteristics of the first centrifugal pump20(seeFIG.1). The first centrifugal pump20has pump characteristics in which a discharge pressure is substantially constant with respect to an arbitrary rotation speed N. That is, the discharge pressure hardly depends on the first flow rate. That is, when the rotation speed N of the first centrifugal pump20is determined, the pressure of the blood sent to the ascending aorta38is determined. In other words, by referring to the pump characteristics inFIG.3, the rotation speed N according to the pressure of the blood sent to the ascending aorta38can be determined. Therefore, the pressure difference between the left ventricle42and the ascending aorta38can be appropriately adjusted by changing the rotation speed N of the first centrifugal pump20.

Note thatFIG.3illustrates pump characteristics when the rotation speed N of the first centrifugal pump20is N1 to N5 (N1<N2<N3<N4<N5).

On the other hand, a pressure loss of the cannula34depends on the flow rate of blood. Therefore, when inner diameters of the first blood removal vessel portion26and the first blood sending vessel portion28decrease, dependency of the pressure loss on the flow rate increases. That is, the pressure loss of the cannula34changes according to the flow rate of blood. In other words, the flow rate of the blood passing through the cannula34changes according to the pressure of the blood before and after along a blood circulation direction in the cannula34.

As illustrated inFIG.1, the first setting section72includes two maps (first map, second map). The first map is a map (not illustrated) indicating a relationship between the first flow rate in the cannula34and a first pressure (pressure of blood flowing through the first blood sending line54). The first setting section72refers to the first map to convert the first target value into the first pressure.

The second map is a map of the pump characteristics ofFIG.3. The first setting section72refers to the second map to determine the rotation speed N according to the converted first pressure. The first control section74controls the rotation speed of the first impeller56by controlling the rotation speed of the first motor62based on the determined rotation speed N. As a result, the first flow rate and the first pressure are controlled, and the pressure difference between the left ventricle42and the ascending aorta38can be appropriately adjusted.

By appropriately adjusting the pressure difference between the left ventricle42and the ascending aorta38, a part of the blood sent to the ascending aorta38flows toward a sinus of Valsalva80as illustrated inFIG.4.

Due to this pressure difference, an aortic valve82formed at a proximal end of the ascending aorta38is closed. When the aortic valve82is closed, as illustrated inFIGS.4and5, the blood flowing into the sinus of Valsalva80flows from the sinus of Valsalva80to left and right coronary arteries84. As a result, it is possible to suppress the occurrence of thrombus in the sinus of Valsalva80. Furthermore, the blood sending to the left and right coronary arteries84can be maintained.

Note that the detection result of the first detection unit22is sequentially input to the first control unit24(seeFIG.1). Therefore, the first setting section72and the first control section74may perform feedback control on the first flow rate on the basis of the first target value and the detection result of the first detection unit22.

The first display section76displays various display contents. The first communication section78transmits and receives signals or information to and from a second control unit96.

As illustrated inFIG.1, the second blood circulation device14includes a second blood circulation circuit90that removes blood from the patient16and sends the blood to the patient16. The second blood circulation circuit90forms a path for extracorporeally circulating blood by sucking blood from the patient16and returning the blood to the patient16again. The second blood circulation device14is a device called “V-A ECMO” that removes blood from a vein of the patient16and sends the blood to an artery of the patient16. The second blood circulation device14further includes a second centrifugal pump92, an oxygenator94, a second detection unit95, and the second control unit96. The second centrifugal pump92is disposed in the second blood circulation circuit90. The second centrifugal pump92assists the heart function of the patient16. The oxygenator94is disposed in the second blood circulation circuit90. The oxygenator94is an extracorporeal membrane oxygenator and assists a pulmonary function of the patient16. The second blood circulation device14circulates the blood of the second blood circulation circuit90by driving the second centrifugal pump92. Note that the second centrifugal pump92may have the same pump characteristics as those of the first centrifugal pump20(seeFIG.3).

The second blood circulation circuit90includes a blood removal cannula98(second blood removal vessel portion), a first connector100, a second blood removal tube102, a second blood sending tube104, a third blood sending tube106, a second connector108, and a blood sending cannula110(second blood sending vessel portion). In the second blood circulation circuit90, the blood removal cannula98, the first connector100, the second blood removal tube102, the second blood sending tube104, the third blood sending tube106, the second connector108, and the blood sending cannula110are disposed in this order along a direction in which blood circulates.

The blood removal cannula98is inserted into a femoral vein112, for example. A distal end of the blood removal cannula98is inserted into a right atrium114of the heart40of the patient16via the femoral vein112. A proximal end of the blood removal cannula98is connected to the first connector100outside the body of the patient16. One end of the second blood removal tube102is connected to the first connector100. The other end of the second blood removal tube102is connected to a second inlet port116of the second centrifugal pump92. The blood removal cannula98, the first connector100, the second blood removal tube102, and the second inlet port116constitute a second blood removal line118for removing blood from the patient16.

One end of the second blood sending tube104is connected to a second outlet port120of the second centrifugal pump92. The other end of the second blood sending tube104is connected to an inlet port122of the oxygenator94. One end of the third blood sending tube106is connected to an outlet port124of the oxygenator94. The other end of the third blood sending tube106is connected to the second connector108outside the body of the patient16. A proximal end of the blood sending cannula110is connected to the second connector108. The blood sending cannula110is inserted into a femoral artery126, for example. Therefore, a distal end of the blood sending cannula110is inserted into the femoral artery126. The second outlet port120, the second blood sending tube104, the oxygenator94, the third blood sending tube106, the second connector108, and the blood sending cannula110constitute a second blood sending line128for sending blood to the patient16.

The second centrifugal pump92functions as a power source for removing blood from the patient16to the outside of the body. Furthermore, the second centrifugal pump92functions as a power source for sending blood into the body of the patient16. The second centrifugal pump92has substantially the same configuration as the first centrifugal pump20. That is, the second centrifugal pump92includes a second impeller130and a second pump housing132that accommodates the second impeller130. The second centrifugal pump92causes the blood to flow by a centrifugal force accompanying the rotation of the second impeller130. That is, the second centrifugal pump92aspirates the blood of the patient16via the second blood removal line118by negative pressure.

Furthermore, the second centrifugal pump92sends blood to the patient16through the second blood sending line128. The second pump housing132is formed of a resin material or the like. The second pump housing132is a hollow cylinder.

The second centrifugal pump92is detachably connected to a second drive device134. The second drive device134includes a second motor136and a second motor housing138that accommodates the second motor136. The second pump housing132and the second motor housing138are detachably connected.

The second impeller130is disposed in an internal space of the second pump housing132. The second impeller130and the second motor136are magnetically coupled via a magnetic coupling portion (not illustrated). Therefore, the second impeller130is rotated by the drive of the second motor136.

The second inlet port116is provided in the second pump housing132. A hollow portion (flow path) of the second inlet port116communicates with an internal space of the second motor housing138. The second inlet port116is formed at a position opposite to a position where the second motor housing138is mounted in the second pump housing132. The second inlet port116is provided on an axis of the second impeller130. The second inlet port116protrudes from the second pump housing132in an axial direction of the second impeller130.

The second pump housing132is further provided with the second outlet port120communicating with the internal space of the second pump housing132. The second outlet port120protrudes from a side wall140of the second pump housing132in a direction intersecting the axis of the second impeller130.

The second centrifugal pump92maybe a volute pump. Furthermore, the second centrifugal pump92may be an open-type pump. In a case where the second centrifugal pump92is an open-type pump, the second impeller130is not provided with a cover that covers a plurality of blades.

The second detection unit95is disposed outside the body of the patient16. Specifically, the second detection unit95is disposed in the middle of the third blood sending tube106. The second detection unit95is a flow rate sensor that detects a flow rate (second flow rate) of blood flowing through the second blood sending line128. The second detection unit95sequentially detects the second flow rate and outputs the detection result to the second control unit96.

The second control unit96includes a second input section150, a second setting section152(flow rate calculation unit), a second control section154, a second display section156, and a second communication section158. The second control unit96is a controller including the second display section156that is a display. The second control unit96controls the second blood circulation device14as a whole by reading and executing a program stored in a memory (not illustrated).

The second input section150is an operator operable by a user. The second input section150is, for example, a touch panel. A user such as a medical worker operates the second input section150to input a target flow rate.

The second setting section152calculates a target value (second target value) of the second flow rate based on the target flow rate and the like. For example, in the blood circulation system10, in a case where only the second blood circulation device14operates, the second setting section152sets the target flow rate to the second target value. Note that, as described above, the target flow rate may change with the lapse of time according to the condition of the patient16. Furthermore, the second target value may change with the lapse of time according to the condition of the patient16.

The second control section154controls a rotation speed of the second motor136based on the second target value calculated by the second setting section152.

Here, setting processing in the second setting section152and control processing of the rotation speed of the second motor136in the second control section154will be described in detail.

Similarly to the first setting section72, the second setting section152includes two maps (third map, fourth map). The third map is a map (not illustrated) indicating a relationship between the second flow rate and a second pressure (pressure of blood flowing through the second blood sending line128). The second setting section152refers to the third map to convert the second target value into the second pressure.

The fourth map is a map of the pump characteristics ofFIG.3. The second setting section152refers to the fourth map to determine the rotation speed N according to the converted second pressure. The rotation speed N is a rotation speed of the second impeller130. The second control section154controls the rotation speed of the second impeller130by controlling the rotation speed of the second motor136based on the determined rotation speed N. As a result, the second flow rate and the second pressure are controlled.

Note that the detection result of the second detection unit95is sequentially input to the second control unit96. Therefore, the second setting section152and the second control section154may perform feedback control on the second flow rate based on the second target value and the detection result of the second detection unit95.

The second display section156displays various display contents. The second communication section158transmits and receives signals or information to and from the first communication section78of the first control unit24.

Incidentally, the condition of the patient16changes with the lapse of time. In a case where both the first blood circulation device12and the second blood circulation device14operate in the blood circulation system10, it is necessary to appropriately adjust the flow rates of blood in the first blood circulation device12and the second blood circulation device14according to the condition of the patient16. Therefore, in the blood circulation system10according to the present embodiment, the centrifugal pump of the other blood circulation device is controlled based on the detection result of the detection unit provided in one blood circulation device.

That is, as described above, the first communication section78and the second communication section158can mutually transmit and receive signals or information. Therefore, the communication section of one blood circulation device transmits the detection result of the detection unit provided in the one blood circulation device and the target flow rate to the communication section of the other blood circulation device. In the other blood circulation device, the centrifugal pump of the other blood circulation device is controlled based on the target flow rate and the detection result received by the communication section. In this case, the target flow rate is the sum of the target value (first target value) of the flow rate of the blood flowing from the first blood circulation device12to the ascending aorta38and the target value (second target value) of the flow rate of the blood flowing from the second blood circulation device14to the ascending aorta38.

That is, in a case where both the first blood circulation device12and the second blood circulation device14operate, one blood circulation device functions as a main device for sending blood to the patient16. The other blood circulation device functions as an auxiliary device for sending blood to the patient16.

First, an operation in a case where the first blood circulation device12is an auxiliary device and the second blood circulation device14is a main device will be described.

First, the user inputs the target flow rate to the second input section150of the second control unit96. Furthermore, the user inputs the second target value to the second input section150. As a result, the second blood circulation device14sends blood to the patient16based on the second target value. In the present description, the second target value changes with the lapse of time according to the condition of the patient16. Note that the target flow rate may change with the lapse of time according to the condition of the patient16.

The second communication section158transmits the input target flow rate and the detection result (second flow rate) of the second detection unit95to the first communication section78of the first control unit24.

The first communication section78outputs the target flow rate received from the second communication section158and the detection result of the second detection unit95to the first setting section72. In a case where the detection result of the second detection unit95is the second flow rate, the first setting section72calculates the first flow rate (first target value) by subtracting the second flow rate from the target flow rate (first target value=target flow rate−second flow rate).

Next, the first setting section72refers to the first map and converts the calculated first target value into the first pressure. Next, the first setting section72refers to the second map to determine the rotation speed N of the first centrifugal pump20according to the converted first pressure.

The first control section74controls the rotation speed of the first impeller56by controlling the rotation speed of the first motor62based on the rotation speed N determined by the first setting section72. As a result, since the first flow rate and the first pressure are controlled in consideration of the second flow rate or the second pressure, the pressure difference between the left ventricle42and the ascending aorta38can be appropriately adjusted.

It is desirable that the target flow rate and the detection result of the second detection unit95are sequentially transmitted from the second communication section158to the first communication section78. As a result, in a case where the second target value changes from moment to moment according to the condition of the patient16, the first setting section72can appropriately calculate the first target value according to the change in the second target value. As a result, the first control section74can appropriately control the rotation speed of the first centrifugal pump20based on the calculated first target value according to the condition of the patient16.

Next, an operation in a case where the first blood circulation device12is a main device and the second blood circulation device14is an auxiliary device will be described.

The user inputs the target flow rate to the first input section70of the first control unit24. Furthermore, the user inputs the first target value to the first input section70. As a result, the first blood circulation device12sends blood to the patient16based on the first target value. In the present description, the first target value changes with the lapse of time according to the condition of the patient16. Note that the target flow rate may change with the lapse of time according to the condition of the patient16.

The first communication section78transmits the input target flow rate and the detection result (first flow rate) of the first detection unit22to the second communication section158of the second control unit96.

The second communication section158outputs the target flow rate received from the first communication section78and the detection result of the first detection unit22to the second setting section152. The second setting section152calculates the second flow rate (second target value) by subtracting the first flow rate from the target flow rate (second target value=target flow rate−first flow rate).

Next, the second setting section152refers to the third map and converts the calculated second target value into the second pressure. Next, the second setting section152refers to the fourth map to determine the rotation speed N of the second centrifugal pump92according to the converted second pressure.

The second control section154controls the rotation speed of the second impeller130by controlling the rotation speed of the second motor136based on the rotation speed N determined by the second setting section152. As a result, the second flow rate and the second pressure are controlled in consideration of the first flow rate or the first pressure.

Preferably, the target flow rate and the detection result of the first detection unit22are sequentially transmitted from the first communication section78to the second communication section158. As a result, in a case where the first target value changes from moment to moment according to the condition of the patient16, the second setting section152can appropriately calculate the second target value according to the change in the first target value. As a result, the second control section154can appropriately control the rotation speed of the second centrifugal pump92based on the calculated second target value according to the condition of the patient16.

Here, the above operation will be described by exemplifying specific numerical values. At the start of the operation of both the first blood circulation device12and the second blood circulation device14, the first flow rate is set as follows. That is, in a case where the second blood circulation device14is the main device and the first blood circulation device12is the auxiliary device, the first flow rate is set as follows. When the target flow rate is 4.0 l/min and second detection unit95detects the second flow rate of 3.5 l/min, the first setting section72sets the first target value to 0.5 l/min (4.0−3.5=0.5).

Thereafter, when the recovery of the patient16progresses, the target flow rate is changed to 4.5 l/min, and the second detection unit95detects the second flow rate of 3.0 l/min, the first setting section72sets the first target value to 1.5 l/min (4.5−3.0=1.5). That is, in a case where the recovery of the patient16progresses, the flow rate of the blood in the second blood circulation device14is reduced, and the flow rate of the blood in the first blood circulation device12is increased.

As described above, since the centrifugal pump of the other blood circulation device can be controlled on the basis of the detection result of the detection unit provided in one blood circulation device, the rotation speeds of the first centrifugal pump20and the second centrifugal pump92can be simultaneously controlled. As a result, the first flow rate and the second flow rate can be appropriately controlled. For example, when the second flow rate changes, the pressure of the ascending aorta38connected to the femoral artery126changes. Therefore, by changing the first target value according to the change in the second flow rate, the rotation speed of the first centrifugal pump20changes. As a result, the first flow rate can be appropriately adjusted.

Furthermore, in the first blood circulation device12, the cannula34is inserted into the subclavian artery36. Therefore, in a case where the second blood circulation device14is removed from the patient16, the feet of patient16can freely move. As a result, the patient16can perform rehabilitation early.

Moreover, in the above description, the case where the target flow rate is input to the input section of one blood circulation device (main device) has been described. In the present embodiment, the setting section of the other blood circulation device (auxiliary device) calculates the flow rate of the blood flowing through the other blood circulation device based on the target flow rate. Therefore, the user may input the target flow rate to the input section of the other blood circulation device.

Moreover,FIG.1illustrates a case where the first blood circulation device12and the second blood circulation device14include the control units24and96, respectively. In some embodiments, the two control units24and96maybe collectively configured as one control unit.

Note that the present invention is not limited to the above-described embodiment, and various configurations can be taken without departing from the gist of the present invention.

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