Patent Description:
As one of professional resuscitation treatments for cardiogenic cardiac arrest patients, there is an invasive percutaneous cardiopulmonary support (PCPS) using an extracorporeal circulator as a percutaneous cardiopulmonary auxilairy device. Such a resuscitation treatment may be referred to as extracorporeal cardiopulmonary resuscitation (ECPR) or extracorporeal membrane oxygenation (ECHO).

For the invasive percutaneous cardiopulmonary support using the extracorporeal circulator, one of important factors is to determine whether a cardiac function (state of the heart) of a patient is recovered. That is, when a withdrawal timing of the extracorporeal circulator is too early with respect to the recovery of the cardiac function of the patient, the heart of the patient cannot stand the withdrawal timing, and it may be necessary to reattach the extracorporeal circulator or the patient may die. On the other hand, when the withdrawal timing of the extracorporeal circulator is too late with respect to the recovery of the cardiac function of the patient, complications such as bleeding may occur due to anticoagulant therapy, consumption of a blood plasma component, or the like. That is, there is an appropriate timing for the withdrawal of the extracorporeal circulator. Further, it is desirable that the withdrawal timing of the extracorporeal circulator can be early ascertained.

During the invasive percutaneous cardiopulmonary support using the extracorporeal circulator, a pump of the extracorporeal circulator removes blood from the patient, causes the blood to pass through an oxygenator, and returns the blood that has passed through the oxygenator to the patient. At this time, a direction of a flow of the blood returned into the body of the patient by the pump is opposite to a direction of a flow of the blood flowing through the body of the patient. That is, the pump returns the blood that has passed through the oxygenator to the patient in a state in which the blood flows retrogradely. Therefore, even in a case in which a flow rate sensor attached to a catheter is delivered to the vicinity of the heart of the patient, it is difficult to only measure a cardiac output. Therefore, in this case, it is difficult to determine the recovery of the cardiac function of the patient with high accuracy.

During the invasive percutaneous cardiopulmonary support using the extracorporeal circulator, there are relatively many facilities in which the flow rate sensor attached to the catheter is not delivered to the vicinity of the heart of the patient. Therefore, also in this case, it is difficult to determine the recovery of the cardiac function of the patient with high accuracy. In order to determine the recovery of the cardiac function, a facility is also present that temporarily stops operations of the extracorporeal circulator and measures the cardiac output. However, in order to reduce a burden on the patient, it is desirable that the recovery of the cardiac function can be determined not intermittently but continuously.

PTL <NUM> discloses a cardiac function evaluation apparatus that calculates a time differential of a blood flow rate measured by a blood flowmeter and evaluates a cardiac function based on a result of the calculation. The cardiac function evaluation apparatus disclosed in PTL <NUM> converts the time differential of the blood flow rate into a time differential of a blood pressure. A relationship between the time differential of the blood flow rate and the time differential of the blood pressure is shown in <FIG> in PTL <NUM>. According to <FIG> described in PTL <NUM>, an error of the time differential of the blood pressure is relatively large even though a cardiac function evaluation block including the blood flowmeter is disposed in the vicinity of the heart of the patient. Therefore, as described above, even when the blood flowmeter is disposed in the vicinity of the heart of the patient, it is difficult to determine the recovery of the cardiac function of the patient with high accuracy.

This disclosure is made to solve the above problem, and an object of this disclosure is to provide a cardiac function measurement system, an extracorporeal circulator, and a cardiac function measurement program that are capable of determining recovery of a cardiac function of a patient with high accuracy.

According to the invention, the above problem is solved by a cardiac function independent claim <NUM>. The dependent claims relate to advantageous embodiments. Claim <NUM> furthermore provides a corresponding cardiac function measurement program executed by a computer.

According to the above, the cardiac function measurement system according to this disclosure determines the withdrawal reference flow rate indicating the theoretical flow rate of the blood transferred from the pump based on the discharge pressure of the pump determined based on the rotation speed of the pump. The cardiac function measurement system determines the measured blood transfer flow rate indicating the realistic flow rate of the blood based on the measurement result of the flow rate measurement unit configured to measure the flow rate of the blood flowing through the circulation circuit of the extracorporeal circulator. Then, the cardiac function measurement system determines the withdrawal timing of the extracorporeal circulator based on the comparison between the withdrawal reference flow rate and the measured blood transfer flow rate. In this manner, the cardiac function measurement system according to this disclosure compares the withdrawal reference flow rate with the measured blood transfer flow rate having a relatively small temporal change, and determines the withdrawal timing of the extracorporeal circulator. Accordingly, the cardiac function measurement system according to this disclosure can determine the recovery of the cardiac function of the patient with high accuracy.

According to the cardiac function measurement system in this disclosure, by calculating the parameter indicating the comparison between the withdrawal reference flow rate and the measured blood transfer flow rate, an output ability of the patient can be quantitatively measured, and the withdrawal timing of the extracorporeal circulator can be determined based on the quantitative comparison. Accordingly, the cardiac function measurement system according to this disclosure can determine the recovery of the cardiac function of the patient with high accuracy.

By using a relatively simple numerical formula, a table, or the like, the cardiac function measurement system according to this disclosure can calculate the difference parameter representing the difference between the withdrawal reference flow rate and the measured blood transfer flow rate as the parameter indicating the comparison between the withdrawal reference flow rate and the measured blood transfer flow rate, and can quantitatively measure the output ability of the patient. Accordingly, the cardiac function measurement system according to this disclosure can easily determine the recovery of the cardiac function of the patient with high accuracy.

In the cardiac function measurement system according to this disclosure, it is preferable that a graph representing a relationship between the parameter and an elapsing time and the parameter are displayed on a display unit.

According to the cardiac function measurement system in this disclosure, by checking the display unit, an operator or the like can easily compare the withdrawal reference flow rate and the measured blood transfer flow rate, and can visually grasp the withdrawal timing of the extracorporeal circulator.

In the cardiac function measurement system according to this disclosure, it is preferable that, a graph representing a relationship between the rotation speed, and the withdrawal reference flow rate and the measured blood transfer flow rate is displayed on the display unit.

According to the cardiac function measurement system in this disclosure, the operator or the like can visually and easily grasp whether the withdrawal timing of the extracorporeal circulator is appropriate by checking the notification displayed on the display unit. Accordingly, the cardiac function measurement system according to this disclosure can prevent the withdrawal timing of the extracorporeal circulator from being too earlier than the recovery of the cardiac function of the patient, and can efficiently assist the determination of the withdrawal timing of the extracorporeal circulator.

In the cardiac function measurement system according to this disclosure, it is preferable that, when a predetermined time elapses after the notification that the withdrawal timing is appropriate is displayed on the display unit, a notification that the withdrawal timing is late is displayed on the display unit.

According to the cardiac function measurement system in this disclosure, the operator or the like can visually and easily grasp whether the withdrawal timing of the extracorporeal circulator is late by checking the notification displayed on the display unit. Accordingly, the cardiac function measurement system according to this disclosure can prevent the withdrawal timing of the extracorporeal circulator from being too later than the recovery of the cardiac function of the patient, and can efficiently assist the determination of the withdrawal timing of the extracorporeal circulator.

In the cardiac function measurement system according to this disclosure, it is preferable that the measured blood transfer flow rate is an average flow rate indicating an average value of a plurality of the realistic flow rates measured by the flow rate measurement unit in a predetermined time.

According to this, the cardiac function measurement system according to this disclosure can determine the withdrawal timing of the extracorporeal circulator by comparing the withdrawal reference flow rate and the measured blood transfer flow rate with each other and quantitatively measuring the output ability of the patient while preventing an influence of pulsations of the heart having a relatively large temporal change. Accordingly, the cardiac function measurement system according to this disclosure can determine the recovery of the cardiac function of the patient with higher accuracy.

According to the extracorporeal circulator in this disclosure, the cardiac function measurement system determines the withdrawal reference flow rate indicating the theoretical flow rate of the blood transferred from the pump based on the discharge pressure of the pump determined based on the rotation speed of the pump. The cardiac function measurement system determines the measured blood transfer flow rate indicating the realistic flow rate of the blood based on the measurement result of the flow rate measurement unit configured to measure the flow rate of the blood flowing through the circulation circuit of the extracorporeal circulator. Then, the cardiac function measurement system determines the withdrawal timing of the extracorporeal circulator based on the comparison between the withdrawal reference flow rate and the measured blood transfer flow rate. In this manner, the cardiac function measurement system compares the withdrawal reference flow rate with the measured blood transfer flow rate having a relatively small temporal change, and determines the withdrawal timing of the extracorporeal circulator. Accordingly, the extracorporeal circulator according to this disclosure can determine the recovery of the cardiac function of the patient with high accuracy.

By executing the cardiac function measurement program according to this disclosure, the withdrawal reference flow rate indicating the theoretical flow rate of the blood transferred from the pump is determined based on the discharge pressure of the pump determined based on the rotation speed of the pump. By executing the cardiac function measurement program, the measured blood transfer flow rate indicating the realistic flow rate of the blood is determined based on the measurement result of the flow rate measurement unit configured to measure the flow rate of the blood flowing through the circulation circuit of the extracorporeal circulator. Then, by executing the cardiac function measurement program, the withdrawal timing of the extracorporeal circulator is determined based on the comparison between the withdrawal reference flow rate and the measured blood transfer flow rate. In this manner, by executing the cardiac function measurement program, the withdrawal reference flow rate is compared with the measured blood transfer flow rate having a relatively small temporal change, and the withdrawal timing of the extracorporeal circulator is determined. Accordingly, by executing the cardiac function measurement program in this disclosure, the recovery of the cardiac function of the patient can be determined with high accuracy.

According to this disclosure, it is possible to provide a cardiac function measurement system, an extracorporeal circulator, and a cardiac function measurement program that are capable of determining recovery of a cardiac function of a patient with high accuracy.

Hereinafter, a preferred embodiment of this disclosure will be described in detail with reference to the drawings.

The embodiment to be described below is a preferred specific example of this disclosure, and thus various technically preferable limitations are applied to the embodiment. However, unless there is any particular mention which limits this disclosure in the description below, the range of this disclosure is not limited to these aspects. In the drawings, the same components are denoted by the same reference numerals, and a detailed description thereof will be omitted as appropriate.

<FIG> is a schematic view showing an extracorporeal circulator according to the embodiment of this disclosure.

An "extracorporeal circulation" performed by an extracorporeal circulator <NUM> shown in <FIG> includes an "extracorporeal circulation operation" and an "auxiliary circulation operation". The extracorporeal circulator <NUM> can perform both the "extracorporeal circulation operation" and the "auxiliary circulation operation".

The "extracorporeal circulation operation" means that when blood circulation in the heart is temporarily stopped due to, for example, cardiac surgery, the extracorporeal circulator <NUM> performs a blood circulation operation and a gas exchange operation (oxygen addition and/or carbon dioxide removal) on the blood.

The "auxiliary circulation operation" means that the extracorporeal circulator <NUM> also performs the blood circulation operation and the gas exchange operation on the blood in a case in which the heart of a patient P cannot perform a sufficient function or in a state in which the lungs cannot perform gas exchange sufficiently. The extracorporeal circulator <NUM> is to be applied to the heart of the patient P. In the description of the present embodiment, the "auxiliary circulation operation" is mainly taken as an example.

For example, the extracorporeal circulator <NUM> is applied to a case in which the heart of the patient P does not operate normally, a case in which the heart of the patient P operates normally but the lungs do not operate normally, and the like. Accordingly, the extracorporeal circulator <NUM> shown in <FIG> is used, for example, in a case of performing the cardiac surgery on the patient P, in subsequent treatment in ICU, and the like. The extracorporeal circulator <NUM> shown in <FIG> performs oxygenator external blood circulation. In the oxygenator external blood circulation, a pump of the extracorporeal circulator <NUM> is operated to remove blood from a vein of a patient, the blood is subjected to the gas exchange by an oxygenator to perform oxygenation of the blood, and then the oxygenated blood is returned to an artery or the vein of the patient again. As described above, the extracorporeal circulator <NUM> is a device that functions as substitutes of the heart and the lung.

As shown in <FIG>, the extracorporeal circulator <NUM> has a circulation circuit 1R that circulates blood. The circulation circuit 1R includes an oxygenator <NUM>, a centrifugal pump <NUM>, a drive motor <NUM> that drives the centrifugal pump <NUM>, a blood removal side catheter (vein side catheter) <NUM>, a blood transfer side catheter (artery side catheter) <NUM>, and a cardiac function measurement system <NUM>. The centrifugal pump <NUM> according to the present embodiment is an example of the "pump" according to this disclosure. The cardiac function measurement system <NUM> includes a control unit <NUM> and is provided as a controller of the extracorporeal circulator <NUM>. The centrifugal pump <NUM> is also referred to as a blood pump or the like, and may be a pump other than the centrifugal pump.

The blood removal side catheter <NUM> is also referred to as a vein side cannula (blood removal side cannula) or the like, and is inserted from a femoral vein. A distal end of the blood removal side catheter <NUM> is indwelled in a right atrium. The blood removal side catheter <NUM> is connected to a blood removal tube (also referred to as a blood removal line) <NUM> via a connector <NUM>, is connected to the centrifugal pump <NUM> via the blood removal tube <NUM>, and guides the blood removed from the patient P to the centrifugal pump <NUM> via the blood removal tube <NUM>. The blood removal tube <NUM> is a conduit that connects the blood removal side catheter <NUM> and the centrifugal pump <NUM>, and is a conduit that guides the blood removed from the patient P to the centrifugal pump <NUM> via the blood removal side catheter <NUM>.

The blood transfer side catheter <NUM> is also referred to as an artery side cannula (blood transfer side cannula) or the like, and is inserted from a femoral artery. The blood transfer side catheter <NUM> is connected to a blood transfer tube (also referred to as a blood transfer line) <NUM> via a connector <NUM>, is connected to the oxygenator <NUM> via the blood transfer tube <NUM>, and guides the blood that has passed through the oxygenator <NUM> to the patient P via the blood transfer tube <NUM>. The blood transfer tube <NUM> is a conduit that connects the oxygenator <NUM> and the blood transfer side catheter <NUM>, and is a conduit that guides the blood to the patient P. The blood has passed through the oxygenator <NUM>.

The drive motor <NUM> controls driving of the centrifugal pump <NUM> based on a command SG of the cardiac function measurement system <NUM>. The centrifugal pump <NUM> is provided downstream of the blood removal side catheter <NUM>, and is driven by receiving a drive force transmitted from the drive motor <NUM>. The centrifugal pump <NUM> removes the blood from the patient P via the blood removal side catheter <NUM> and the blood removal tube <NUM>, transfers the blood to the oxygenator <NUM>, and then returns the blood to the patient P via the blood transfer tube <NUM> and the blood transfer side catheter <NUM>. The centrifugal pump <NUM> transmits a signal G related to a rotation speed of the centrifugal pump <NUM> to the cardiac function measurement system <NUM>.

The oxygenator <NUM> is provided downstream of the centrifugal pump <NUM>. Specifically, the oxygenator <NUM> is disposed between the centrifugal pump <NUM> and the blood transfer tube <NUM>. The oxygenator <NUM> performs the gas exchange operation (oxygen addition and/or carbon dioxide removal) on the blood. The oxygenator <NUM> is, for example, a membrane-type oxygenator, and is particularly preferably a hollow fiber membrane-type oxygenator. Oxygen gas is supplied to the oxygenator <NUM> through an oxygen supply tube <NUM>.

As the blood removal tube <NUM> and the blood transfer tube <NUM>, for example, conduits made of a highly transparent, elastically deformable, and flexible synthetic resin such as vinyl chloride resin or silicone rubber are used. The blood, which is a liquid, flows in a V1 direction and a V2 direction in the blood removal tube <NUM>, and flows in a V3 direction in the blood transfer tube <NUM>.

The cardiac function measurement system <NUM> acquires various types of information, executes calculation, generates a control signal for controlling operations of devices such as the drive motor <NUM> and an external monitor <NUM>, and transmits the control signal to each device. In other words, the cardiac function measurement system <NUM> manages the extracorporeal circulator <NUM>. Details of the cardiac function measurement system <NUM> will be described below. The cardiac function measurement system <NUM> may include a touch panel <NUM> (see <FIG>) as an input unit capable of inputting various types of information and as a display unit that displays various types of information. That is, the "display unit" according to this disclosure may be the external monitor <NUM> provided separately from the cardiac function measurement system <NUM>, or may be the touch panel <NUM> provided in the cardiac function measurement system <NUM>. The touch panel <NUM> can detect contact, or the like, of a finger of an operator or the like.

The extracorporeal circulator <NUM> according to the present embodiment further includes a flow rate measurement unit <NUM> and the external monitor (display unit) <NUM>. The external monitor <NUM> according to the present embodiment is an example of the "display unit" according to this disclosure. In the following description, a case in which the "display unit" according to this disclosure is the external monitor <NUM> will be described as an example.

The flow rate measurement unit <NUM> is provided in the circulation circuit 1R. In the extracorporeal circulator <NUM> according to the present embodiment, the flow rate measurement unit <NUM> is provided in the circulation circuit 1R between the oxygenator <NUM> and the blood transfer side catheter <NUM>. Specifically, the flow rate measurement unit <NUM> is provided on the blood transfer tube <NUM>. By providing the flow rate measurement unit <NUM> on the blood transfer tube <NUM>, the flow rate measurement unit <NUM> can measure a flow rate of blood immediately before being returned to the patient P, and can measure a flow rate of blood flowing through the circulation circuit 1R at a position relatively close to the patient P. However, an arrangement position of the flow rate measurement unit <NUM> is not limited to the blood transfer tube <NUM>, and may be any position in the circulation circuit 1R. In the following description, a case in which the flow rate measurement unit <NUM> is provided on the blood transfer tube <NUM> will be described as an example.

The flow rate measurement unit <NUM> is, for example, a flow rate sensor, and detects a flow rate of blood flowing inside the circulation circuit 1R. The flow rate measurement unit <NUM> shown in <FIG> measures a flow rate of the blood transferred from the centrifugal pump <NUM>. The flow rate measurement unit <NUM> transmits a signal S1 related to the flow rate of the blood flowing inside the circulation circuit 1R to the cardiac function measurement system <NUM>. In the present embodiment, the flow rate measurement unit <NUM> transmits, to the cardiac function measurement system <NUM>, the signal S1 related to the flow rate of the blood transferred from the centrifugal pump <NUM>. Examples of the flow rate measurement unit <NUM> includes an ultrasound flowmeter. As the ultrasound flowmeter, for example, an ultrasound propagation time difference type flowmeter is used. However, the flow rate measurement unit <NUM> is not limited to the ultrasound flowmeter.

<FIG> is a schematic diagram illustrating a flow of blood returned from the extracorporeal circulator to a patient and a flow of blood transferred from the heart of the patient.

<FIG> is a block diagram illustrating the control unit and the flow rate measurement unit according to the present embodiment.

In the block diagram shown in <FIG>, the oxygenator is omitted for convenience of explanation.

As indicated by an arrow A1 shown in <FIG> and an arrow A3 shown in <FIG>, the blood returned from the centrifugal pump <NUM> to the patient P via the blood transfer tube <NUM> and the blood transfer side catheter <NUM> flows toward a heart P1 of the patient P through, for example, the artery. On the other hand, as indicated by an arrow A2 shown in <FIG> and an arrow A4 shown in <FIG>, the blood transferred from the heart P1 of the patient P and oxygenated in the lungs of the patient P passes through the artery and flows toward peripheral blood vessels of the head and peripheral blood vessels of the lower limb.

As described above, a direction of the flow of the blood returned into the body of the patient P by the centrifugal pump <NUM> is opposite to a direction of the flow of the blood flowing through the inside of the body of the patient P. That is, the centrifugal pump <NUM> returns the blood that has passed through the oxygenator <NUM> to the patient P in a state in which the blood flows retrogradely.

As shown in <FIG>, the control unit <NUM> of the cardiac function measurement system <NUM> includes a central processing unit (CPU) <NUM> and a field programmable gate array (FPGA) <NUM>. For example, the CPU <NUM> transmits, to the FPGA <NUM> every <NUM> milliseconds (ms), a signal S2 for requesting a measurement of the flow rate of the blood transferred from the centrifugal pump <NUM>. The FPGA <NUM> receives the signal S2 transmitted from the CPU <NUM>, and transmits, to the flow rate measurement unit <NUM> every <NUM>, a signal S3 for requesting the measurement of the flow rate of the blood transferred from the centrifugal pump <NUM>. The flow rate measurement unit <NUM> receives the signal S3 transmitted from the FPGA <NUM>, measures, every <NUM>, the flow rate of the blood transferred from the centrifugal pump <NUM>, and transmits a signal S4 related to the measured flow rate of the blood to the FPGA <NUM>. The FPGA <NUM> receives the signal S4 transmitted from the flow rate measurement unit <NUM>, and transmits, to the CPU <NUM>, a signal S5 related to an average value of the flow rate in a most recent one second.

In the present embodiment, the flow rate measurement unit <NUM> measures the flow rate of the blood every <NUM> and transmits the signal S4 related to the measured flow rate of the blood to the FPGA <NUM>. Therefore, <NUM> pieces (<NUM>/<NUM>) of measurement data are present per second. Therefore, the FPGA <NUM> calculates an average value of the <NUM> pieces of measurement data as the average value of the flow rate in the most recent one second, and transmits the signal S5 related to the average value of the flow rate to the CPU <NUM>. The CPU <NUM> receives the signal S5 transmitted from the FPGA <NUM>, and performs control to display the flow rate of the blood transferred from the centrifugal pump <NUM> on the external monitor (display unit) <NUM> as the measured blood transfer flow rate. In the present embodiment, the measured blood transfer flow rate is the average value of the flow rates in the most recent one second, that is, the average value of the <NUM> pieces of measurement data.

A period in which the flow rate measurement unit <NUM> measures the flow rate of the blood is not limited to <NUM>. A predetermined time for the CPU <NUM> to calculate the average value of the flow rate of the blood is not limited to one second.

<FIG> is a block diagram illustrating a configuration of main units of the cardiac function measurement system according to the present embodiment.

The cardiac function measurement system <NUM> according to the present embodiment includes a computer <NUM> and a storage unit <NUM>. The computer <NUM> includes the control unit <NUM> (see <FIG> and <FIG>), reads a program <NUM> stored in the storage unit <NUM>, and executes various calculations and processes. The storage unit <NUM> stores the program <NUM> (cardiac function measurement program) executed by the computer <NUM>. The program <NUM> according to the present embodiment is an example of the "cardiac function measurement program" according to this disclosure. Examples of the storage unit <NUM> include a hard disk drive (HDD). The program <NUM> is not limited to being stored in the storage unit <NUM>, and may be stored in advance and distributed in a computer-readable storage medium, or may be downloaded to the cardiac function measurement system <NUM> via a network. The storage unit <NUM> may be an external storage device connected to the computer <NUM>.

Next, the configuration of the main units of the cardiac function measurement system <NUM> according to the present embodiment will be further described with reference to the drawings.

<FIG> is a block diagram illustrating the configuration of the main units of the cardiac function measurement system according to the present embodiment.

The cardiac function measurement system <NUM> according to the present embodiment includes the control unit <NUM>, the storage unit <NUM>, the touch panel <NUM>, and a communication unit <NUM>. The control unit <NUM> reads the program <NUM> (see <FIG>) stored in the storage unit <NUM> and executes various calculations and processes. The control unit <NUM> includes a display processing unit <NUM>, a notification processing unit <NUM>, a pump discharge pressure determination unit <NUM>, a withdrawal reference flow rate determination unit <NUM>, a measured blood transfer flow rate determination unit <NUM>, a parameter calculation unit <NUM>, and a withdrawal timing determination unit <NUM>. The display processing unit <NUM>, the notification processing unit <NUM>, the pump discharge pressure determination unit <NUM>, the withdrawal reference flow rate determination unit <NUM>, the measured blood transfer flow rate determination unit <NUM>, the parameter calculation unit <NUM>, and the withdrawal timing determination unit <NUM> are implemented by the computer <NUM> executing the program <NUM> stored in the storage unit <NUM>. The display processing unit <NUM>, the notification processing unit <NUM>, the pump discharge pressure determination unit <NUM>, the withdrawal reference flow rate determination unit <NUM>, the measured blood transfer flow rate determination unit <NUM>, the parameter calculation unit <NUM>, and the withdrawal timing determination unit <NUM> may be implemented by hardware or may be implemented by a combination of hardware and software. The storage unit <NUM> stores the program <NUM> described above with reference to <FIG>, and includes a withdrawal reference flow rate storage unit <NUM> and a pump characteristic storage unit <NUM>.

The display processing unit <NUM> executes a process of displaying, on the external monitor <NUM>, at least one of the rotation speed of the centrifugal pump <NUM> based on the signal G that is related to the rotation speed and that is transmitted from the centrifugal pump <NUM>, a withdrawal reference flow rate determined by the withdrawal reference flow rate determination unit <NUM>, the measured blood transfer flow rate determined by the measured blood transfer flow rate determination unit <NUM>, a parameter calculated by the parameter calculation unit <NUM>, and a withdrawal timing of the extracorporeal circulator <NUM> determined by the withdrawal timing determination unit <NUM>. In the present embodiment, the "withdrawal reference flow rate" is a theoretical flow rate of the blood transferred from the centrifugal pump <NUM> based on a discharge pressure of the centrifugal pump <NUM> when the heart of the patient P is healthy and strong, and is determined by the withdrawal reference flow rate determination unit <NUM>. The "measured blood transfer flow rate" is a realistic flow rate of the blood (in the present embodiment, the blood transferred from the centrifugal pump <NUM>) flowing through the circulation circuit 1R, and is determined by the measured blood transfer flow rate determination unit <NUM> based on a measurement result of the flow rate measurement unit <NUM>. Details of the parameter calculated by the parameter calculation unit <NUM> and the withdrawal timing of the extracorporeal circulator <NUM> will be described later.

As will be described later, the display processing unit <NUM> can display a graph representing a relationship between the rotation speed of the centrifugal pump <NUM> and the measured blood transfer flow rate on the external monitor <NUM>, and can display a graph representing a relationship between the parameter calculated by the parameter calculation unit <NUM> and an elapsing time on the external monitor <NUM>.

When a predetermined condition is satisfied, the notification processing unit <NUM> executes a process of displaying on the external monitor <NUM> that the withdrawal timing of the extracorporeal circulator <NUM> is appropriate or displaying on the external monitor <NUM> that the withdrawal timing of the extracorporeal circulator <NUM> is late. The notification processing unit <NUM> may execute a notification method by, for example, generating light or sound.

The pump discharge pressure determination unit <NUM> refers to the pump characteristic of the centrifugal pump <NUM> stored in the pump characteristic storage unit <NUM>, and determines the discharge pressure of the centrifugal pump <NUM> based on the signal G (that is, the rotation speed of the centrifugal pump <NUM>) related to the rotation speed transmitted from the centrifugal pump <NUM>.

Here, an example of the pump characteristic of the centrifugal pump <NUM> stored in the pump characteristic storage unit <NUM> will be described with reference to <FIG>.

<FIG> is a graph showing the example of the pump characteristic stored in the pump characteristic storage unit according to the present embodiment.

A horizontal axis of the graph shown in <FIG> represents the flow rate (L/min) of the blood transferred from the centrifugal pump <NUM>. A vertical axis of the graph shown in <FIG> represents the discharge pressure (mmHg) of the centrifugal pump <NUM>. As shown in <FIG>, the relationship between the flow rate in the centrifugal pump <NUM> and the discharge pressure of the centrifugal pump <NUM> is represented by a curve or a straight line for each rotation speed of the centrifugal pump <NUM>. The discharge pressure of the centrifugal pump <NUM> slightly decreases as the flow rate in the centrifugal pump <NUM> increases, and when the rotational speed of the centrifugal pump <NUM> is the same, the discharge pressure of the centrifugal pump <NUM> does not change much and is substantially constant depending on the flow rate in the centrifugal pump <NUM>.

For example, when the rotation speed of the centrifugal pump <NUM> is <NUM> rpm and the flow rate in the centrifugal pump <NUM> is <NUM>/min, the discharge pressure of the centrifugal pump <NUM> is approximately <NUM> mmHg. For example, when the rotation speed of the centrifugal pump <NUM> is <NUM> rpm and the flow rate in the centrifugal pump <NUM> is <NUM>/min, the discharge pressure of the centrifugal pump <NUM> is approximately <NUM> mmHg. For example, when the rotation speed of the centrifugal pump <NUM> is <NUM> rpm and the flow rate in the centrifugal pump <NUM> is <NUM>/min, the discharge pressure of the centrifugal pump <NUM> is approximately <NUM> mmHg. As described above, in the example of the pump characteristic shown in <FIG>, when the rotation speed of the centrifugal pump <NUM> is doubled, the discharge pressure of the centrifugal pump <NUM> becomes approximately four times, and when the rotation speed of the centrifugal pump <NUM> is tripled, the discharge pressure of the centrifugal pump <NUM> becomes approximately nine times. That is, in the example of the pump characteristic shown in <FIG>, the discharge pressure of the centrifugal pump <NUM> is substantially proportional to a square of the rotation speed of the centrifugal pump <NUM>.

In this manner, the pump discharge pressure determination unit <NUM> refers to the pump characteristic of the centrifugal pump <NUM> stored in the pump characteristic storage unit <NUM>, and determines the discharge pressure of the centrifugal pump <NUM> based on the rotation speed of the centrifugal pump <NUM>.

The pump characteristic of the centrifugal pump <NUM> stored in the pump characteristic storage unit <NUM> is not limited to the graph shown in <FIG>, and may be other graphs. In that case, as the pump characteristic of the centrifugal pump, depending on a type of the centrifugal pump, there is a centrifugal pump in which a change in the discharge pressure with respect to a change in the flow rate is relatively large. Therefore, when such a centrifugal pump <NUM> is used, the pump discharge pressure determination unit <NUM> can determine the discharge pressure of the centrifugal pump <NUM> based on, in addition to the signal G that is related to the rotation speed and that is transmitted from the centrifugal pump <NUM>, the signal S4 transmitted from the flow rate measurement unit <NUM> or the measured blood transfer flow rate determined by the measured blood transfer flow rate determination unit <NUM>. The pump characteristic of the centrifugal pump <NUM> stored in the pump characteristic storage unit <NUM> is not limited to the graph representing the relationship between the rotation speed of the centrifugal pump <NUM> and the discharge pressure of the centrifugal pump <NUM>, and may be, for example, a numerical formula representing the relationship between the rotation speed of the centrifugal pump <NUM> and the discharge pressure of the centrifugal pump <NUM>, or a form (table) representing the relationship between the rotation speed of the centrifugal pump <NUM> and the discharge pressure of the centrifugal pump <NUM>.

Next, returning to <FIG>, the configuration of the main units of the cardiac function measurement system <NUM> according to the present embodiment will be further described.

The withdrawal reference flow rate determination unit <NUM> refers to a withdrawal reference flow rate characteristic stored in the withdrawal reference flow rate storage unit <NUM>, and determines the withdrawal reference flow rate indicating the theoretical flow rate of the blood transferred from the centrifugal pump <NUM> based on the discharge pressure of the centrifugal pump <NUM> determined by the pump discharge pressure determination unit <NUM>. The withdrawal reference flow rate characteristic stored in the withdrawal reference flow rate storage unit <NUM> represents a relationship between the discharge pressure or the rotation speed of the centrifugal pump <NUM> and the flow rate in the centrifugal pump <NUM> when the heart of the patient P is healthy and strong. For example, the withdrawal reference flow rate characteristic stored in the withdrawal reference flow rate storage unit <NUM> is a graph, a numerical formula, a form (table), or the like representing the relationship between the discharge pressure or the rotation speed of the centrifugal pump <NUM> and the flow rate in the centrifugal pump <NUM> when the heart of the patient P is healthy and strong.

The withdrawal reference flow rate characteristic stored in the withdrawal reference flow rate storage unit <NUM> may include patient information (height, weight, age, gender, and the like). In this case, in consideration of the patient information, the withdrawal reference flow rate determination unit <NUM> can determine the withdrawal reference flow rate based on the discharge pressure of the centrifugal pump <NUM> determined by the pump discharge pressure determination unit <NUM>.

The measured blood transfer flow rate determination unit <NUM> determines the realistic flow rate of the blood (in the present embodiment, the blood transferred from the centrifugal pump <NUM>) flowing through the circulation circuit 1R based on the measurement result of the flow rate measurement unit <NUM>. The measured blood transfer flow rate determined by the measured blood transfer flow rate determination unit <NUM> is an average flow rate indicating an average value of a plurality of realistic flow rates measured by the flow rate measurement unit <NUM> in a predetermined time. For example, as described above with reference to <FIG> and <FIG>, the measured blood transfer flow rate determination unit <NUM> calculates the average value of <NUM> pieces of measurement data as the average value of the flow rate in the most recent one second, and determines the average flow rate indicated by the average value as the measured blood transfer flow rate.

As described above with reference to <FIG> and <FIG>, the direction of the flow of the blood returned into the body of the patient P by the centrifugal pump <NUM> is opposite to the direction of the flow of the blood flowing through the body of the patient P. Therefore, when the heart of the patient P is healthy and strong, the blood returned into the body of the patient P by the centrifugal pump <NUM> tends to be relatively strongly pushed back by the blood transferred from the heart P1 of the patient P. Accordingly, when the heart of the patient P is healthy and strong, the flow rate of the blood transferred from the centrifugal pump <NUM> is relatively small. In other words, when the heart of the patient P is healthy and strong, the flow rate of the blood measured by the flow rate measurement unit <NUM> is relatively small.

On the other hand, when the heart of the patient P is not healthy and is weak, the blood returned into the body of the patient P by the centrifugal pump <NUM> tends to be relatively weakly pushed back by the blood transferred from the heart P1 of the patient P. Accordingly, when the heart of the patient P is not healthy and is weak, the flow rate of the blood transferred from the centrifugal pump <NUM> is relatively large. In other words, when the heart of the patient P is not healthy and is weak, the flow rate of the blood measured by the flow rate measurement unit <NUM> is relatively large.

The parameter calculation unit <NUM> calculates a parameter indicating a comparison between the withdrawal reference flow rate determined by the withdrawal reference flow rate determination unit <NUM> and the measured blood transfer flow rate determined by the measured blood transfer flow rate determination unit <NUM>. Specifically, the parameter calculation unit <NUM> calculates a difference parameter representing a difference between the withdrawal reference flow rate determined by the withdrawal reference flow rate determination unit <NUM> and the measured blood transfer flow rate determined by the measured blood transfer flow rate determination unit <NUM>. Details of the parameter calculated by the parameter calculation unit <NUM> will be described later.

The withdrawal timing determination unit <NUM> determines the withdrawal timing of the extracorporeal circulator <NUM> based on the comparison between the withdrawal reference flow rate and the measured blood transfer flow rate. Specifically, the withdrawal timing determination unit <NUM> determines the withdrawal timing of the extracorporeal circulator <NUM> based on the parameter calculated by the parameter calculation unit <NUM>. For example, when the parameter calculated by the parameter calculation unit <NUM> is included in a predetermined range, the withdrawal timing determination unit <NUM> determines that the withdrawal timing of the extracorporeal circulator <NUM> is appropriate. On the other hand, when the parameter calculated by the parameter calculation unit <NUM> is not included in the predetermined range, the withdrawal timing determination unit <NUM> determines that the withdrawal timing of the extracorporeal circulator <NUM> is not appropriate.

The withdrawal reference flow rate storage unit <NUM> stores the withdrawal reference flow rate characteristic. The withdrawal reference flow rate characteristic represents the relationship between the discharge pressure or the rotation speed of the centrifugal pump <NUM> and the flow rate in the centrifugal pump <NUM> when the heart of the patient P is healthy and strong. For example, the withdrawal reference flow rate characteristic is a graph, a numerical formula, a form (table), or the like representing the relationship between the discharge pressure or the rotation speed of the centrifugal pump <NUM> and the flow rate in the centrifugal pump <NUM> when the heart of the patient P is healthy and strong. The withdrawal reference flow rate characteristic may include the patient information (height, weight, age, gender, and the like).

The pump characteristic storage unit <NUM> stores a characteristic of the centrifugal pump <NUM>. For example, as shown in <FIG>, the characteristic of the centrifugal pump <NUM> shows the relationship between the flow rate (L/min) of the blood transferred from the centrifugal pump <NUM> and the discharge pressure (that is, a lifting height) (mmHg) of the centrifugal pump <NUM>. For example, in the graph showing the characteristic of the centrifugal pump <NUM>, the relationship between the flow rate (L/min) of the blood transferred from the centrifugal pump <NUM> and the discharge pressure (mmHg) of the centrifugal pump <NUM> is set according to the rotation speed (rpm) of the centrifugal pump <NUM>.

The touch panel <NUM> is an example of the "display unit" according to this disclosure, and can display various types of information and detect contact, or the like, of a finger of an operator or the like. The touch panel <NUM> transmits, to the control unit <NUM>, information input by an operator or the like in response to an operation of the operator or the like.

The communication unit <NUM> communicates with the drive motor <NUM>, the external monitor <NUM>, and the flow rate measurement unit <NUM>, and transmits and receives various types of information and various types of signals.

Here, for the auxiliary circulation operation using the extracorporeal circulator <NUM>, one of important factors is to determine whether the cardiac function (state of the heart P1) of the patient P is recovered. That is, when the withdrawal timing of the extracorporeal circulator <NUM> is too early with respect to the recovery of the cardiac function of the patient P, the heart P1 of the patient P cannot stand the withdrawal timing, and it may be necessary to reattach the extracorporeal circulator <NUM> or the patient P may die. On the other hand, when the withdrawal timing of the extracorporeal circulator <NUM> is too late with respect to the recovery of the cardiac function of the patient P, complications such as bleeding may occur due to anticoagulant therapy, consumption of a blood plasma component, or the like. That is, there is an appropriate timing for the withdrawal of the extracorporeal circulator <NUM>. Further, it is desirable that the withdrawal timing of the extracorporeal circulator <NUM> can be early ascertained.

As described above with reference to <FIG> and <FIG>, the direction of the flow of the blood returned into the body of the patient P by the centrifugal pump <NUM> is opposite to the direction of the flow of the blood flowing through the body of the patient P. That is, the centrifugal pump <NUM> returns the blood that has passed through the oxygenator <NUM> to the patient P in a state in which the blood flows retrogradely. Therefore, it is difficult to only measure a cardiac output, and it is difficult to determine recovery of the cardiac function of a patient with high accuracy.

On the other hand, in the cardiac function measurement system <NUM> according to the present invention, the withdrawal reference flow rate determination unit <NUM> determines the withdrawal reference flow rate indicating the theoretical flow rate of the blood transferred from the centrifugal pump <NUM> based on the discharge pressure of the centrifugal pump <NUM> determined by the pump discharge pressure determination unit <NUM> based on the rotation speed of the centrifugal pump <NUM>. The measured blood transfer flow rate determination unit <NUM> determines the measured blood transfer flow rate indicating the realistic flow rate of the blood transferred from the centrifugal pump <NUM> based on the measurement result of the flow rate measurement unit <NUM> that measures the flow rate of the blood transferred from the centrifugal pump <NUM>. For example, the measured blood transfer flow rate determination unit <NUM> determines, as the measured blood transfer flow rate, the average flow rate indicating the average value of the plurality of realistic flow rates measured by the flow rate measurement unit <NUM> in the predetermined time. The parameter calculation unit <NUM> calculates the parameter indicating the comparison between the withdrawal reference flow rate determined by the withdrawal reference flow rate determination unit <NUM> and the measured blood transfer flow rate determined by the measured blood transfer flow rate determination unit <NUM>. Then, the withdrawal timing determination unit <NUM> determines the withdrawal timing of the extracorporeal circulator <NUM> based on the comparison between the withdrawal reference flow rate and the measured blood transfer flow rate. Specifically, the withdrawal timing determination unit <NUM> determines the withdrawal timing of the extracorporeal circulator <NUM> based on the parameter calculated by the parameter calculation unit <NUM>. That is, the withdrawal timing determination unit <NUM> determines whether the withdrawal timing of the extracorporeal circulator <NUM> is appropriate.

According to the present embodiment, the cardiac function measurement system <NUM> compares the withdrawal reference flow rate with the measured blood transfer flow rate having a relatively small temporal change, and determines the withdrawal timing of the extracorporeal circulator <NUM>. Accordingly, the cardiac function measurement system <NUM> according to the present embodiment can determine the recovery of the cardiac function of the patient P with high accuracy. When the withdrawal timing determination unit <NUM> determines the withdrawal timing of the extracorporeal circulator <NUM> based on the parameter calculated by the parameter calculation unit <NUM>, the cardiac function measurement system <NUM> can quantitatively measure output ability of the patient P and determine the withdrawal timing of the extracorporeal circulator <NUM> based on a quantitative comparison. Accordingly, the cardiac function measurement system <NUM> according to the present embodiment can determine the recovery of the cardiac function of the patient P with high accuracy.

Next, a specific example of the operations of the cardiac function measurement system according to the present embodiment will be described with reference to the drawings.

<FIG> and <FIG> are flowcharts showing the specific example of the operations of the cardiac function measurement system according to the present embodiment.

<FIG> is a schematic view showing a first specific example of a screen displayed on the display unit according to the present embodiment.

<FIG> is a schematic view showing a second specific example of the screen displayed on the display unit according to the present embodiment.

The specific example of the operations of the cardiac function measurement system <NUM> according to the present embodiment will be described with reference to <FIG> and <FIG>. In the present specific example, for convenience of explanation, a process executed after the extracorporeal circulator <NUM> is attached to the patient P will be described.

First, in step S11, the cardiac function measurement system <NUM> receives the signal G (see <FIG>) related to the rotation speed of the centrifugal pump <NUM> from the centrifugal pump <NUM>. Specifically, the communication unit <NUM> of the cardiac function measurement system <NUM> receives the signal G related to the rotation speed of the centrifugal pump <NUM> from the drive motor <NUM> that drives the centrifugal pump <NUM>.

Subsequently, in step S12, the cardiac function measurement system <NUM> receives, from the flow rate measurement unit <NUM> via the communication unit <NUM>, the signal S1 (see <FIG>) related to the flow rate of the blood transferred from the centrifugal pump <NUM>. The process in step S12 may not necessarily be executed after the process in step S11, and may be executed simultaneously with the process in step S11.

Subsequently, in step S13, the pump discharge pressure determination unit <NUM> refers to the pump characteristic of the centrifugal pump <NUM> stored in the pump characteristic storage unit <NUM>, and determines the discharge pressure of the centrifugal pump <NUM> based on the rotation speed of the centrifugal pump <NUM>. The pump characteristic of the centrifugal pump <NUM> stored in the pump characteristic storage unit <NUM> is as described above with reference to <FIG> and <FIG>.

Subsequently, in step S14, the withdrawal reference flow rate determination unit <NUM> refers to the withdrawal reference flow rate characteristic stored in the withdrawal reference flow rate storage unit <NUM>, and determines the withdrawal reference flow rate indicating the theoretical flow rate of the blood transferred from the centrifugal pump <NUM> based on the discharge pressure of the centrifugal pump <NUM> determined by the pump discharge pressure determination unit <NUM>.

Subsequently, in step S15, the measured blood transfer flow rate determination unit <NUM> determines the realistic flow rate of the blood transferred from the centrifugal pump <NUM> based on the measurement result of the flow rate measurement unit <NUM>. For example, as described above with reference to <FIG> and <FIG>, the measured blood transfer flow rate determination unit <NUM> calculates the average value of <NUM> pieces of measurement data as the average value of the flow rate in the most recent one second, and determines the average flow rate indicated by the average value as the measured blood transfer flow rate. That is, for example, the measured blood transfer flow rate determined by the measured blood transfer flow rate determination unit <NUM> is the average flow rate indicating the average value of the plurality of realistic flow rates measured by the flow rate measurement unit <NUM> in the predetermined time.

Subsequently, in step S16, the parameter calculation unit <NUM> calculates the parameter indicating the comparison between the withdrawal reference flow rate determined by the withdrawal reference flow rate determination unit <NUM> and the measured blood transfer flow rate determined by the measured blood transfer flow rate determination unit <NUM>.

The parameter calculation unit <NUM> calculates the difference parameter representing the difference between the withdrawal reference flow rate determined by the withdrawal reference flow rate determination unit <NUM> and the measured blood transfer flow rate determined by the measured blood transfer flow rate determination unit <NUM>.

Subsequently, in step S17, the display processing unit <NUM> executes a process of displaying, on the external monitor (display unit) <NUM>, information on the parameter that is calculated by the parameter calculation unit <NUM> and that indicates the comparison between the withdrawal reference flow rate and the measured blood transfer flow rate.

Here, the first specific example of the screen displayed on the external monitor <NUM> will be described with reference to <FIG>. In the first specific example shown in <FIG>, the display processing unit <NUM> displays, on the external monitor <NUM>, a graph representing a relationship between the rotation speed of the centrifugal pump <NUM> and the withdrawal reference flow rate and the measured blood transfer flow rate. A horizontal axis of the graph shown in <FIG> represents the rotation speed (rpm) of the centrifugal pump <NUM>. A vertical axis of the graph shown in <FIG> represents the flow rate (L/min) of the blood transferred from the centrifugal pump <NUM>.

A line FR1 shown in <FIG> is an approximate line related to the withdrawal reference flow rate characteristic. In other words, the line FR1 shown in <FIG> is an approximate line representing the relationship between the rotation speed of the centrifugal pump <NUM> and the flow rate in the centrifugal pump <NUM> when the heart of the patient P is healthy and strong. The approximate line related to the withdrawal reference flow rate characteristic is not limited to the regression line (line FR1) shown in <FIG>, and may be a quadratic curve. For example, the line FR1 shown in <FIG> is displayed in a bluish color such as blue or green on the external monitor <NUM>.

A line FR2 shown in <FIG> is an approximate line related to the measured blood transfer flow rate determined by the measured blood transfer flow rate determination unit <NUM> when the heart of the patient P is not healthy and is weak. In other words, the line FR2 is an approximate line representing the relationship between the rotation speed of the centrifugal pump <NUM> and the flow rate in the centrifugal pump <NUM> when the heart of the patient P is not healthy and is weak. The approximate line related to the measured blood transfer flow rate is not limited to the regression line (line FR2) shown in <FIG>, and may be a quadratic curve. For example, the line FR2 shown in <FIG> is displayed in a reddish color such as red, pink, or orange on the external monitor <NUM>.

A slope of the regression line (line FR1 and line FR2) shown in <FIG> is, for example, approximately <NUM> (L/min/rpm). However, the slope of the regression line (line FR1 and line FR2) is not limited to <NUM> (L/min/rpm). The slope of the regression line (line FR1 and line FR2) may be calculated based on "an amount of a change in the flow rate in the centrifugal pump <NUM>/an amount of a change in the rotation speed of the centrifugal pump <NUM>" by the operator or the like changing, in order to match arrangement conditions of the case, the rotation speed of the centrifugal pump <NUM> by, for example, approximately ±<NUM> rpm in an initial stage in which the extracorporeal circulator <NUM> is attached to the patient P.

In the first specific example shown in <FIG>, marks at "<NUM>:<NUM> on January <NUM>" and "<NUM>:<NUM> on January <NUM>" representing the relationship between the rotation speed of the centrifugal pump <NUM> and the measured blood transfer flow rate are located near the line FR2. On the other hand, a mark at "<NUM>:<NUM> on January <NUM>" representing the relationship between the rotation speed of the centrifugal pump <NUM> and the measured blood transfer flow rate is located near the line FR1. As described above, when the cardiac function of the patient P is recovered, the blood returned into the body of the patient P by the centrifugal pump <NUM> relatively strongly tends to be pushed back by the blood transferred from the heart P1 of the patient P, and as compared with the flow rate at the same rotation speed of the centrifugal pump <NUM>, the measured blood transfer flow rate decreases. That is, when the cardiac function of the patient P is recovered, as indicated by an arrow A5 shown in <FIG>, the mark representing the relationship between the rotation speed of the centrifugal pump <NUM> and the measured blood transfer flow rate moves downward and approaches the line FR1 serving as the approximate line related to the withdrawal reference flow rate characteristic.

In the first specific example shown in <FIG>, the parameter calculated by the parameter calculation unit <NUM> is displayed on the external monitor <NUM> as a difference parameter representing a difference between the withdrawal reference flow rate and the measured blood transfer flow rate at the same rotation speed of the centrifugal pump <NUM>. That is, in the first specific example shown in <FIG>, the parameter calculated by the parameter calculation unit <NUM> corresponds to a difference DY between an intercept of a flow rate axis (Y axis) of the line FR2 and an intercept of the flow rate axis (Y axis) of the line FR1.

Alternatively, the parameter calculated by the parameter calculation unit <NUM> may be displayed on the external monitor <NUM> as a difference parameter representing a difference between the withdrawal reference flow rate and the measured blood transfer flow rate at the same flow rate of the blood transferred from the centrifugal pump <NUM>. That is, the parameter calculated by the parameter calculation unit <NUM> may correspond to a difference DX between an intercept of a rotation speed axis (X axis) of the line FR2 and an intercept of the rotation speed axis (X axis) of the line FR1.

The display processing unit <NUM> may display, between the line FR1 and the line FR2, a plurality of approximate lines representing the relationship between the rotation speed of the centrifugal pump <NUM> and the flow rate in the centrifugal pump <NUM>. That is, the display processing unit <NUM> may display, between the line FR1 and the line FR2, a plurality of approximate lines indicating degrees of the recovery of the cardiac function of the patient P. Alternatively, the display processing unit <NUM> may display, between the line FR1 and the line FR2, the degrees of the recovery of the cardiac function of the patient P in colors or a shading gradation.

The second specific example of the screen displayed on the external monitor <NUM> will be described with reference to <FIG>. In the second specific example shown in <FIG>, the display processing unit <NUM> displays, on the external monitor <NUM>, the graph representing the relationship between the parameter calculated by the parameter calculation unit <NUM> and the elapsing time, and the parameter calculated by the parameter calculation unit <NUM>. That is, the second specific example shown in <FIG> displays a graph <NUM> representing the relationship between the parameter calculated by the parameter calculation unit <NUM> and the elapsing time. A horizontal axis of the graph <NUM> shown in <FIG> represents the elapsing time (for example, date and time) after the extracorporeal circulator <NUM> is attached to the patient P. A vertical axis of the graph <NUM> shown in <FIG> represents the parameter calculated by the parameter calculation unit <NUM>.

In the second specific example shown in <FIG>, the parameter calculated by the parameter calculation unit <NUM> is calculated using, for example, the following equation, and is displayed on the external monitor <NUM> as the difference parameter representing the difference between the withdrawal reference flow rate and the measured blood transfer flow rate at the same rotation speed of the centrifugal pump <NUM>.

As described above with reference to <FIG>, a parameter CP corresponds to the difference DY between the intercept of the flow rate axis (Y axis) of the line FR2 and the intercept of the flow rate axis (Y axis) of the line FR1. The symbol "M" in Equation (<NUM>) represents the rotation speed of the centrifugal pump <NUM> received from the centrifugal pump <NUM> by the communication unit <NUM>. The symbol "F" in Equation (<NUM>) represents the measured blood transfer flow rate determined by the measured blood transfer flow rate determination unit <NUM>.

The numerical value "<NUM>" in Equation (<NUM>) corresponds to the slope of the regression line (line FR1 and line FR2) described above with reference to <FIG>. As described above with reference to <FIG>, the slope of the regression line (line FR1 and line FR2), that is, the numerical value "<NUM>" in Equation (<NUM>) is not limited to <NUM> (L/min/rpm). The numerical values "<NUM>" and "<NUM>" in Equation (<NUM>) are numerical values for convenience in easily grasping or identifying the parameter CP, and may be appropriately set in consideration of a "weight" or the like.

In the second specific example shown in <FIG>, when the cardiac function of the patient P is recovered, and the blood returned into the body of the patient P by the centrifugal pump <NUM> relatively strongly tends to be pushed back by the blood transferred from the heart P1 of the patient P, the parameter CP calculated using Equation (<NUM>) is set to be large. That is, the graph <NUM> shown in <FIG> shows a state in which the cardiac function of the patient P is recovered with the elapsing time.

In the second specific example shown in <FIG>, the parameter CP calculated by the parameter calculation unit <NUM> is displayed as a numerical value on the external monitor <NUM>. Accordingly, the operator or the like can intuitively grasp the parameter CP indicating the degree of the recovery of the cardiac function of the patient P as the numerical value by checking the external monitor <NUM>.

In the second specific example shown in <FIG>, a measured blood transfer flow rate (LMP: L/min) <NUM> determined by the measured blood transfer flow rate determination unit <NUM>, a rotation speed (RPM) <NUM> of the centrifugal pump <NUM> received from the centrifugal pump <NUM> by the communication unit <NUM>, and an Index (L/min/m2) <NUM> indicating a flow rate of blood per body surface of the patient P are displayed on the external monitor <NUM>.

Returning to <FIG>, the specific example of the operations of the cardiac function measurement system <NUM> according to the present embodiment will be further described. In step S18 following step S17, the withdrawal timing determination unit <NUM> determines the withdrawal timing of the extracorporeal circulator <NUM> based on the parameter that is calculated by the parameter calculation unit <NUM> and that indicates the comparison between the withdrawal reference flow rate and the measured blood transfer flow rate. That is, the withdrawal timing determination unit <NUM> determines whether the withdrawal timing of the extracorporeal circulator <NUM> is appropriate. For example, as indicated by the arrow A5 shown in <FIG>, when the mark (circular mark in <FIG>) representing the relationship between the rotation speed of the centrifugal pump <NUM> and the measured blood transfer flow rate approaches the line FR1 serving as the approximate line related to the withdrawal reference flow rate characteristic and the parameter calculated by the parameter calculation unit <NUM> is included in the predetermined range, the withdrawal timing determination unit <NUM> determines that the withdrawal timing of the extracorporeal circulator <NUM> is appropriate. For example, in the first specific example described above with reference to <FIG>, when the difference DY between the intercept of the flow rate axis (Y axis) of the line FR2 and the intercept of the flow rate axis (Y axis) of the line FR1 is equal to or less than a predetermined value, the withdrawal timing determination unit <NUM> determines that the withdrawal timing of the extracorporeal circulator <NUM> is appropriate. For example, in the second specific example described above with reference to <FIG>, when the parameter CP calculated by the parameter calculation unit <NUM> is equal to or more than a predetermined value, the withdrawal timing determination unit <NUM> determines that the withdrawal timing of the extracorporeal circulator <NUM> is appropriate.

According to the invention, when the withdrawal timing of the extracorporeal circulator <NUM> is appropriate (step S18: YES), in step S19, the notification processing unit <NUM> notifies on the external monitor <NUM> that the withdrawal timing of the extracorporeal circulator <NUM> is appropriate. For example, in the first specific example described above with reference to <FIG>, when the withdrawal timing of the extracorporeal circulator <NUM> is appropriate, the notification processing unit <NUM> adds a bluish color such as blue or green to the mark (circular mark in <FIG>) representing the relationship between the rotation speed of the centrifugal pump <NUM> and the measured blood transfer flow rate. For example, in the second specific example described above with reference to <FIG>, when the withdrawal timing of the extracorporeal circulator <NUM> is appropriate, the notification processing unit <NUM> adds a bluish color such as blue or green to the graph <NUM> representing the relationship between the parameter calculated by the parameter calculation unit <NUM> and the elapsing time, and the parameter CP calculated by the parameter calculation unit <NUM>.

Alternatively, when the withdrawal timing of the extracorporeal circulator <NUM> is appropriate, the notification processing unit <NUM> may display on the external monitor <NUM> that the withdrawal timing of the extracorporeal circulator <NUM> is appropriate in a pop-up manner using characters, figures, symbols, or the like. Alternatively, the notification processing unit <NUM> may notify, by a sound, that the withdrawal timing of the extracorporeal circulator <NUM> is appropriate.

On the other hand, when the withdrawal timing of the extracorporeal circulator <NUM> is not appropriate (step S18: NO), the process described above in step S11 is executed. In step S20 following step S19, the control unit <NUM> determines whether the extracorporeal circulator <NUM> is withdrawn from the patient P. When the extracorporeal circulator <NUM> is withdrawn from the patient P (step S20: YES), the control unit <NUM> ends the operations of the cardiac function measurement system <NUM>.

On the other hand, when the extracorporeal circulator <NUM> is not withdrawn from the patient P (step S20: NO), in step S21, the control unit <NUM> determines whether a predetermined time elapses after the notification processing unit <NUM> notifies on the external monitor <NUM> that the withdrawal timing of the extracorporeal circulator <NUM> is appropriate. For example, the control unit <NUM> uses a timer function of the control unit <NUM> to measure an elapsing time after the notification processing unit <NUM> notifies on the external monitor <NUM> that the withdrawal timing of the extracorporeal circulator <NUM> is appropriate.

When the predetermined time elapses after the notification processing unit <NUM> notifies on the external monitor <NUM> that the withdrawal timing of the extracorporeal circulator <NUM> is appropriate (step S21: YES), in step S22, the notification processing unit <NUM> notifies on the external monitor <NUM> that the timing at which the extracorporeal circulator <NUM> is withdrawn from the patient P is late. For example, the notification processing unit <NUM> displays on the external monitor <NUM> that the timing at which the extracorporeal circulator <NUM> is withdrawn from the patient P is late in a pop-up manner using characters, figures, symbols, or the like. Alternatively, the notification processing unit <NUM> may notify, by a sound, that the timing at which the extracorporeal circulator <NUM> is withdrawn from the patient P is late.

On the other hand, when the predetermined time does not elapse after the notification processing unit <NUM> notifies on the external monitor <NUM> that the withdrawal timing of the extracorporeal circulator <NUM> is appropriate (step S21: NO), the process described above with reference to step S20 is executed.

According to the cardiac function measurement system <NUM> in the present specific example, the parameter calculation unit <NUM> can calculate the difference parameter representing the difference between the withdrawal reference flow rate and the measured blood transfer flow rate as the parameter indicating the comparison between the withdrawal reference flow rate and the measured blood transfer flow rate using a relatively simple numerical formula, a table, or the like. Further, the withdrawal timing determination unit <NUM> can quantitatively determine whether the withdrawal timing of the extracorporeal circulator <NUM> is appropriate. That is, the cardiac function measurement system <NUM> can quantitatively measure output ability of a patient. Accordingly, the cardiac function measurement system <NUM> according to the present specific example can easily determine the recovery of the cardiac function of the patient P with high accuracy.

The measured blood transfer flow rate determined by the measured blood transfer flow rate determination unit <NUM> is the average flow rate indicating the average value of the plurality of realistic flow rates measured by the flow rate measurement unit <NUM> in the predetermined time, and thus, the withdrawal timing determination unit <NUM> can determine the withdrawal timing of the extracorporeal circulator <NUM> by comparing the withdrawal reference flow rate and the measured blood transfer flow rate with each other and quantitatively measuring the output ability of the patient P while preventing an influence of pulsations of the heart P1 having a relatively large temporal change. Accordingly, the cardiac function measurement system <NUM> according to the present specific example can determine the recovery of the cardiac function of the patient P with higher accuracy.

In the first specific example described above with reference to <FIG>, the display processing unit <NUM> displays, on the external monitor <NUM>, the graph representing the relationship between the rotation speed of the centrifugal pump <NUM> and the withdrawal reference flow rate and the measured blood transfer flow rate. In the second specific example described above with reference to <FIG>, the display processing unit <NUM> displays, on the external monitor <NUM>, the graph representing the relationship between the parameter calculated by the parameter calculation unit <NUM> and the elapsing time, and the parameter calculated by the parameter calculation unit <NUM>. According to the above, by checking the external monitor <NUM>, the operator or the like can easily compare the withdrawal reference flow rate and the measured blood transfer flow rate, and can visually grasp the withdrawal timing of the extracorporeal circulator <NUM>.

When the withdrawal timing of the extracorporeal circulator <NUM> is appropriate, the notification processing unit <NUM> notifies on the external monitor <NUM> that the withdrawal timing of the extracorporeal circulator <NUM> is appropriate. Accordingly, the operator or the like can visually and easily grasp whether the withdrawal timing of the extracorporeal circulator <NUM> is appropriate by checking the notification displayed on the external monitor <NUM>. Accordingly, the cardiac function measurement system <NUM> according to the present specific example can prevent the withdrawal timing of the extracorporeal circulator <NUM> from being too earlier than the recovery of the cardiac function of the patient P, and can efficiently assist the determination of the withdrawal timing of the extracorporeal circulator <NUM>.

When the predetermined time elapses after the notification processing unit <NUM> notifies on the external monitor <NUM> that the withdrawal timing of the extracorporeal circulator <NUM> is appropriate, the notification processing unit <NUM> notifies on the external monitor <NUM> that the timing at which the extracorporeal circulator <NUM> is withdrawn from the patient P is late. Accordingly, the operator or the like can visually and easily grasp whether the withdrawal timing of the extracorporeal circulator <NUM> is late by checking the notification displayed on the external monitor <NUM>. Accordingly, the cardiac function measurement system <NUM> according to the present specific example can prevent the withdrawal timing of the extracorporeal circulator <NUM> from being too later than the recovery of the cardiac function of the patient P, and can efficiently assist the determination of the withdrawal timing of the extracorporeal circulator <NUM>.

Next, experiments conducted by the present inventors will be described with reference to the drawings.

<FIG> is a block diagram illustrating a first circulation system set in a present experiment.

<FIG> is a block diagram illustrating a second circulation system set in the present experiment.

<FIG> is a graph showing an example of a relationship between a rotation speed of the centrifugal pump and a measured blood transfer flow rate that are obtained in the present experiment.

<FIG> is a graph showing an example of the parameter CP calculated by the parameter calculation unit in the present experiment.

The present inventors set a circulation system imitating a blood vessel of a human body and the circulation circuit 1R (see <FIG>) using a tube made of a highly transparent, elastically deformable, and flexible synthetic resin such as vinyl chloride resin or silicone rubber. Arrows shown in a first circulation system 11R shown in <FIG> and a second circulation system 12R shown in <FIG> represent flows of a liquid imitating blood, and also represent the blood vessel of the human body and tubes imitating the blood removal side catheter <NUM>, the blood removal tube <NUM>, the blood transfer tube <NUM>, and the blood transfer side catheter <NUM>.

Lengths of the tubes are each set to approximately <NUM> or more and <NUM> or less for convenience of the experiment. The first circulation system 11R and the second circulation system 12R are disposed at positions having substantially the same height. Accordingly, a drop pressure does not necessarily need to be taken into consideration.

Each of the first circulation system 11R and the second circulation system 12R includes a pump <NUM>, a first pressure sensor <NUM>, a second pressure sensor <NUM>, a flow rate sensor <NUM>, a check valve <NUM>, a first clamp <NUM>, a second clamp <NUM>, a bifurcated portion <NUM>, a buffer tank <NUM>, the centrifugal pump <NUM>, the drive motor <NUM>, a third pressure sensor <NUM>, a fourth pressure sensor <NUM>, and the flow rate measurement unit <NUM>.

The pump <NUM> is a pump imitating the heart P1 of the patient P, is appropriately controlled to reproduce the pulsations of the heart P1 of the patient P, and is alternately driven at a relatively high rotation speed (that is, high discharge pressure) and a relatively low rotation speed (that is, low discharge pressure). In a pattern assuming that the heart of the patient P is healthy and strong, <NUM> RPM is set as the high rotation speed of the pump <NUM>, and <NUM> RPM is set as the low rotation speed of the pump <NUM>. On the other hand, in a pattern assuming that the heart P1 of the patient P is not healthy and is weak, <NUM> RPM is set as the high rotation speed of the pump <NUM>, and <NUM> RPM is set as the low rotation speed of the pump <NUM>.

A drive time of the pump <NUM> at a high rotation speed is <NUM> seconds. A drive time of the pump <NUM> at a low rotation speed is <NUM> seconds. That is, in the present experiment, a cycle of the pump <NUM> is <NUM> second. In other words, the pump <NUM> is appropriately controlled to reproduce the pulsations of the heart P1 of the patient P, and is driven with a pulsation number of <NUM> bpm.

The first pressure sensor <NUM> is disposed in a tube <NUM> imitating a path through which the blood flows from a vena cava toward the heart P1 of the patient P, and detects a pressure of the liquid flowing through the tube <NUM>. The second pressure sensor <NUM> detects a pressure of the liquid transferred from the pump <NUM>. The flow rate sensor <NUM> detects a flow rate of the liquid transferred from the pump <NUM>. The first clamp <NUM> is an adjustment tool that reproduces peripheral resistance on a lower limb side of the patient P. The second clamp <NUM> is an adjustment tool that reproduces peripheral resistance on a head side of the patient P. The bifurcated portion <NUM> is a portion imitating an insertion portion of the blood transfer side catheter <NUM> with respect to the femoral artery.

The third pressure sensor <NUM> is disposed in a tube <NUM> imitating the blood removal tube <NUM> as a path through which the blood removed from the femoral vein of the patient P flows toward the centrifugal pump <NUM>, and detects a pressure of the liquid flowing through the tube <NUM>. The fourth pressure sensor <NUM> detects a pressure of the liquid transferred from the centrifugal pump <NUM>. The centrifugal pump <NUM>, the drive motor <NUM>, and the flow rate measurement unit <NUM> are as described above with reference to <FIG>.

In the first circulation system 11R shown in <FIG>, the present inventors adjusted an opening degree of the first clamp <NUM> such that a measurement result of the flow rate sensor <NUM> becomes approximately <NUM>/min when the rotation speed of the pump <NUM> is <NUM> RPM (that is, the discharge pressure of the pump <NUM> is approximately <NUM> mmHg) in a state in which the second clamp <NUM> is closed. On the other hand, in the second circulation system 12R shown in <FIG>, the present inventors adjusted opening degrees of the first clamp <NUM> and the second clamp <NUM> such that a flow rate of the liquid flowing through each of a tube in which the first clamp <NUM> is disposed and a tube in which the second clamp <NUM> is disposed becomes approximately <NUM>/min when the rotation speed of the pump <NUM> is <NUM> RPM (that is, the discharge pressure of the pump <NUM> is approximately <NUM> mmHg).

The present inventors set the rotation speed of the centrifugal pump <NUM> in a range of approximately <NUM> RPM or more and <NUM> RPM or less, and recorded a flow rate value of the liquid transferred from the centrifugal pump <NUM>. The recorded flow rate value is an average value of a plurality of pieces of measurement data measured for one second by the flow rate measurement unit <NUM>.

An example of results of the present experiment is as shown in <FIG>. That is, <FIG> is a graph obtained as one example of the results of the present experiment, and is a graph illustrating an example of a relationship between the rotation speed of the centrifugal pump <NUM> and the flow rate value of the liquid transferred from the centrifugal pump <NUM> (that is, the average value of the plurality of pieces of measurement data measured for one second by the flow rate measurement unit <NUM>). A horizontal axis of the graph shown in <FIG> represents the rotation speed (rpm) of the centrifugal pump <NUM>. A vertical axis of the graph shown in <FIG> represents the flow rate value (L/min) of the liquid transferred from the centrifugal pump <NUM>. That is, the graph shown in <FIG> corresponds to the graph described above with reference to <FIG>.

A line FR11 shown in <FIG> is an example of an experimental result of a pattern assuming a case in which the heart of the patient P is healthy and strong in the first circulation system 11R. A line FR12 shown in <FIG> is an example of an experimental result of a pattern assuming a case in which the heart of the patient P is not healthy and is weak in the first circulation system 11R. A line FR21 shown in <FIG> is an example of an experimental result of a pattern assuming a case in which the heart of the patient P is healthy and strong in the second circulation system 12R. A line FR22 shown in <FIG> is an example of an experimental result of a pattern assuming a case in which the heart of the patient P is not healthy and is weak in the second circulation system 12R.

According to the graph shown in <FIG>, in each of the first circulation system 11R and the second circulation system 12R, the lines FR11, FR21 of the experimental result of the pattern assuming the case in which the heart of the patient P is healthy and strong are located below the lines FR12, FR22 of the experimental result of the pattern assuming the case in which the heart of the patient P is not healthy and is weak. That is, as indicated by an arrow shown in <FIG>, when the cardiac function of the patient P is recovered, the mark representing the relationship between the rotation speed of the centrifugal pump <NUM> and the flow rate value of the liquid transferred from the centrifugal pump <NUM> moves downward. Therefore, as described above with reference to <FIG>, it was checked in the present experiment that, when the cardiac function of the patient P is recovered, the mark representing the relationship between the rotation speed of the centrifugal pump <NUM> and the measured blood transfer flow rate moves downward and approaches the line FR1 serving as the approximate line related to the withdrawal reference flow rate characteristic.

<FIG> is a graph showing an example of the parameter CP in each assumed pattern of the present experiment. A horizontal axis of the graph shown in <FIG> represents the assumed pattern of the present experiment. A vertical axis of the graph shown in <FIG> represents the parameter CP calculated by the parameter calculation unit <NUM>. The parameter CP is as described above with reference to <FIG>, and is the parameter calculated using, for example, Equation (<NUM>). The parameter CP shown in <FIG> is an average value of a plurality of values calculated using Equation (<NUM>) based on a plurality of rotation speeds of the centrifugal pump <NUM> and a plurality of flow rate values of the liquid transferred from the centrifugal pump <NUM>.

That is, the parameter CP of the pattern 11R1 assuming the case in which the heart of the patient P is healthy and strong in the first circulation system 11R is an average value of a plurality of values calculated based on seven pieces of measurement data (rotation speed and flow rate) on the line FR11 shown in <FIG>. The parameter CP of the pattern 11R2 assuming the case in which the heart of the patient P is not healthy and is weak in the first circulation system 11R is an average value of a plurality of values calculated based on five pieces of measurement data on the line FR12 shown in <FIG>. The parameter CP of the pattern 12R1 assuming the case in which the heart of the patient P is healthy and strong in the second circulation system 12R is an average value of a plurality of values calculated based on eight pieces of measurement data on the line FR21 shown in <FIG>. The parameter CP of the pattern 12R2 assuming the case in which the heart of the patient P is not healthy and is weak in the second circulation system 12R is an average value of a plurality of values calculated based on six pieces of measurement data on the line FR22 shown in <FIG>.

According to the graph shown in <FIG>, it was checked in the present experiment that, in both of the first circulation system 11R and the second circulation system 12R, the parameters CP of the patterns 11R1, 12R1 assuming the case in which the heart of the patient P is healthy and strong have a correlation higher than that of the parameters CP of the patterns 11R2, 12R2 assuming the case in which the heart of the patient P is not healthy and is weak.

The equation used for calculating the parameter CP is not limited to Equation (<NUM>) described above with reference to <FIG>, and may be another equation. For example, the equation for calculating the parameter CP may be appropriately set such that the parameter CP in the case in which the heart of the patient P is healthy and strong has a correlation lower than that of the parameter CP in the case where the heart of the patient P is not healthy and is weak.

The embodiment according to this disclosure has been described above. However, the invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention which is solely defined by the appended claims.

Claim 1:
A cardiac function measurement system (<NUM>) that is disposed in an extracorporeal circulator (<NUM>) and that is configured to measure a cardiac function of a patient (P), wherein
the cardiac function measurement system (<NUM>) is configured
to detect a rotation speed of a pump (<NUM>) configured to remove blood from the patient (P) and return the blood to the patient (P),
to determine a discharge pressure of the pump (<NUM>) based on the rotation speed,
to determine a withdrawal reference flow rate indicating a theoretical flow rate of the blood transferred from the pump (<NUM>) based on the discharge pressure,
characterized in that
said cardiac function measurement system is also configured
to determine a measured blood transfer flow rate (<NUM>) indicating a realistic flow rate of the blood based on a measurement result of a flow rate measurement unit (<NUM>) configured to measure a flow rate of the blood flowing through a circulation circuit (1R) of the extracorporeal circulator (<NUM>),
calculate a difference parameter (CP) representing a difference between the withdrawal reference flow rate and the measured blood transfer flow rate (<NUM>),
determine the withdrawal timing of the extracorporeal circulator (<NUM>) based on the parameter (CP), and when the withdrawal timing is determined, a notification that the withdrawal timing is appropriate is displayed on a display unit.