WO2014128763A1 - Circulation device, control device, and information processing method - Google Patents

Abstract

A circulation device, wherein bubbles which are small in volume can be detected with high precision. The present invention is a circulation device which circulates the blood of a subject extracorporeally using a circulation circuit, and which is equipped with a bubble sensor, a calculation means for calculating the variance per unit of time of a signal output by the bubble sensor, an extraction means for extracting the period of time from when the variance per unit of time calculated by the calculation means exceeds a first reference value until the variance drops below a second reference value, and an assessment means for assessing as a bubble each of the level changes included in the signal output by the detection means over the period of time extracted by the extraction means.

Description

Circulation device, control device and information processing method

The present invention relates to information processing technology in a circulation device.

Generally, in a circulation device that performs extracorporeal circulation, auxiliary circulation, and the like, a bubble sensor is provided in the circulation circuit to monitor whether or not bubbles are mixed in the blood sent to the subject. In addition, when a bubble of a predetermined size is detected, the clamp is closed to avoid adverse effects on the subject due to the bubble, and blood supply to the subject is stopped. We are taking measures such as.

JP 2008-220417 A

However, bubbles that adversely affect the subject are not only bubbles having a predetermined size, but, for example, when they break up into small bubbles that flow continuously as a group of fine bubbles for a certain period of time. In addition, it is considered that the bubble group adversely affects the subject.

In particular, when the blood sending speed is high, the mixed bubbles break up and often flow in a group of many small bubbles, so that such small-sized bubbles can be detected, and It is desirable that the total amount of bubbles be monitored by cumulative addition.

On the other hand, the bubble sensor is usually configured to output a signal that lowers the level according to the size of the bubble. In the case of a small volume bubble, the level of the output signal is small and is distinguished from noise. It is a difficult situation to do.

For this reason, it is indispensable for a circulating apparatus to detect a large number of small bubbles separately from noise or the like.

The present invention has been made in view of the above problems, and an object of the present invention is to make it possible to accurately detect bubbles having a small volume in a circulation device.

In order to achieve the above object, the circulation device according to the present invention has the following configuration. That is,
A circulation device that circulates the blood of a subject outside the body using a circulation circuit,
Detecting means arranged in the circulation circuit and outputting a signal whose level changes according to the size of each bubble mixed in the circulated blood;
A calculation means for sequentially calculating a variance value per unit time of the signal output from the detection means;
An extraction means for extracting a time zone from when the variance value per unit time calculated by the calculation means exceeds the first reference value to below the second reference value;
And determining means for determining that each level change included in the signal output from the detecting means in the time zone extracted by the extracting means is a bubble.

According to the present invention, it is possible to accurately detect a small-sized bubble in the circulation device.

Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. In the accompanying drawings, the same or similar components are denoted by the same reference numerals.

The accompanying drawings are included in the specification, constitute a part thereof, show an embodiment of the present invention, and are used to explain the principle of the present invention together with the description.
FIG. 1 is a diagram showing an overall configuration of an extracorporeal circulation device according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a functional configuration of the controller of the extracorporeal circulation apparatus. FIG. 3 is a diagram illustrating an example of an output signal of the bubble sensor and a dispersion value of the output signal. FIG. 4 is a diagram showing the change over time of the cumulative value of the volume of bubbles. FIG. 5 is a flowchart showing the flow of the bubble amount calculation process in the controller.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiment described below is a preferred specific example of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these embodiments.

[First Embodiment]
<1. Overall configuration of extracorporeal circulation device>
First, an overall configuration of an extracorporeal circulation device according to an embodiment of the present invention will be described. 1A of FIG. 1 is a diagram illustrating an example of the overall configuration of an extracorporeal circulation device 100 according to an embodiment of the present invention.

The extracorporeal circulation device 100 is called PCPS (percutaneous cardiopulmonary support) and performs cardiopulmonary assist operations (extracorporeal circulation operation, priming operation). The extracorporeal circulation apparatus 100 has a blood extracorporeal circuit (hereinafter referred to as a circulation circuit) indicated by an arrow in the figure. When the cardiopulmonary assist operation is started, the extracorporeal circulation device 100 performs an extracorporeal circulation operation for extracorporeally circulating the blood of the subject 130 using this circulation circuit after performing a priming operation.

The priming operation refers to an operation of removing bubbles in the circuit by circulating the priming solution in the circulation circuit in a state where the circulation circuit is sufficiently filled with the priming solution (for example, physiological saline).

As shown in FIG. 1A, the extracorporeal circulation device 100 includes a controller 110 that functions as a control device, a drive motor 111, a centrifugal pump 112, an artificial lung 113, an oxygen supply source 117, a catheter (venous side). 119, a catheter (arterial side) 120, a bubble sensor 114, a flow sensor 115, a blood filter 116, a branch line 118, and a clamp 122. These components are connected by a flexible tube or the like, and the lumen of the tube forms a flow path for blood or priming liquid.

The catheter (arterial side) 120 pumps blood toward the body of the subject 130, and the catheter (venous side) 119 performs blood removal from the body of the subject 130.

The centrifugal pump 112 is also called a centrifugal artificial heart, drives a rotating body provided inside, applies pressure to the blood, and circulates the blood in the circulation circuit. The drive motor 111 gives a rotational driving force to the rotating body of the centrifugal pump 112.

The artificial lung 113 performs blood circulation and blood gas exchange (oxygen addition, carbon dioxide removal, etc.). The oxygen supply source 117 is realized by, for example, an oxygen cylinder and supplies oxygen to be added to blood. The oxygen supplied from the oxygen supply source 117 is used at the time of gas exchange by the artificial lung 113.

The bubble sensor 114 detects bubbles contained in blood flowing in the circulation circuit during the extracorporeal circulation operation by a predetermined detection method (ultrasonic wave, light, etc.). The blood filter 116 filters blood or removes bubbles in the blood. The flow sensor 115 includes, for example, a built-in ultrasonic transceiver, and detects the flow rate of the priming liquid or blood in the circulation circuit.

The clamp 122 is a member for closing the tube so as to forcibly stop the blood supply toward the body of the subject 130 during the extracorporeal circulation operation. The clamp 122 is operated when an automatic control mode for automatically performing a closing operation is set when it is determined that an abnormality that stops blood supply has occurred based on an output signal from the bubble sensor 114. Is possible.

The branch line 118 switches the flow path of the circulation circuit. Specifically, during an extracorporeal circulation operation in which the blood of the subject 130 is circulated extracorporeally, a circulation circuit passing through the body of the subject 130 is constructed as shown in 1A of FIG. Circulate blood. During the priming operation, as shown in 1B of FIG. 1, the circuit of the circulation circuit to the inside of the body of the subject 130 is blocked by the branch line 118 (in other words, the circulation circuit that passes only the outside of the subject 130 (in other words, the subject A circulation circuit that does not pass through the body of the person 130 is constructed, and the circulation circuit is filled with the priming liquid (without passing through the body of the subject) to circulate the priming liquid. On the circulation circuit, one or a plurality of bubble discharge ports (not shown) for discharging bubbles are provided. By circulating a plurality of priming liquids in the circulation circuit, the bubbles in the circulation circuit are circulated. It will be discharged from the bubble discharge port.

The controller 110 comprehensively controls the extracorporeal circulation operation and the priming operation in the extracorporeal circulation device 100. In the controller 110, for example, the centrifugal motor 112 is driven by controlling the drive motor 111. Further, the bubble sensor 114 is controlled to acquire an output signal from the bubble sensor 114, or the flow rate sensor 115 is controlled to acquire a flow rate value. Further, in the automatic control mode, when it is determined that there is an abnormality that requires blood supply to be stopped based on the output signal from the bubble sensor 114, the clamp 122 is closed.

Next, the flow of processing when performing cardiopulmonary assist operation (extracorporeal circulation operation, priming operation) using the extracorporeal circulation device 100 shown in FIGS. 1A and 1B will be briefly described.

When the cardiopulmonary assist operation is started, the controller 110 controls the execution of the priming operation. During the priming operation, a circulation circuit that does not pass through the body of the subject 130 is constructed by the branch line 118 as shown in 1B of FIG. At this time, the priming liquid supply source 121 is connected to the branch line 118, and the priming liquid is supplied from the priming liquid supply source 121 into the circulation circuit. As a result, the circulation circuit is filled with the priming liquid.

Then, the centrifugal pump 112 is driven by the control of the controller 110, and the priming liquid circulates in the circulation circuit. Bubbles in the circulation circuit are discharged from the bubble discharge port or the like with this circulation. In addition, the bubble sensor 114 may detect whether or not there is a function of flowing in the circulation circuit during the priming operation.

The user who confirms that the priming is completed switches the branch line 118 and constructs a circulation circuit that passes through the body of the subject 130 as shown in FIG. 1A. Thereby, the blood of the subject 130 is circulated extracorporeally.

When the extracorporeal circulation operation starts, blood that has been removed from the catheter (vein side) 119 enters the oxygenator 113 via the centrifugal pump 112. In the artificial lung 113, as described above, gas exchange, that is, processing such as oxygen addition and carbon dioxide removal is performed. Thereafter, the filtered blood is sent from the catheter (arterial side) 120 into the body of the subject 130 through the blood filter 116 and the like. The blood flow of the subject 130 from the catheter (vein side) 119 to the catheter (arterial side) 120 is continuously performed. Note that, even during the extracorporeal circulation operation, the bubble sensor 114 detects bubbles in the circulation circuit, and processing according to the output signal (clamp closing operation or the like in the automatic control mode) is executed.

The above is an explanation of an example of the overall configuration of the extracorporeal circulation device 100 according to the present embodiment and the flow of cardiopulmonary assist operation. Note that the configuration of the extracorporeal circulation device 100 shown in FIGS. 1A and 1B is merely an example, and the configuration may be changed as appropriate.

<2. Functional configuration of controller>
Next, an example of a functional configuration of the controller 110 illustrated in FIG. 1 will be described with reference to FIG.

The controller 110 has, as its functional configuration, a control unit (computer) 201, an operation unit 202, a display unit 203, a timer unit 204, a storage unit (computer-readable recording medium) 205, and an I / F unit 206. And a communication unit 207.

The control unit 201 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and various programs for realizing the above-described cardiopulmonary assist operation are stored in the ROM. It is assumed that

The operation unit 202 is realized by, for example, various buttons and inputs an instruction from a medical worker. The display unit 203 is realized by, for example, a display device such as a monitor (including an output unit that outputs an alarm sound), and displays various types of information to a medical worker. Note that a part or all of the operation unit 202 and the display unit 203 may be realized as a touch panel with an audio speaker, for example.

The timer unit 204 measures various times. The storage unit 205 is realized by a ROM, a RAM, and the like, and is executed by the control unit 201 in the interlocking operation control mode, and is based on an output signal from the bubble sensor 114 during the extracorporeal circulation operation, and is a cumulative value of the volume of bubbles. A program for functioning as the bubble amount calculation unit 210 for calculating the value is stored. The output signal output from the bubble sensor 114 during the extracorporeal circulation operation is stored as the bubble data 211. The details of the bubble amount calculation process realized by using the bubble data 211 acquired by the control unit 201 executing a program that functions as the bubble amount calculation unit 210 will be described later. The storage unit 205 may be mounted in the control unit 201.

The I / F unit 206 exchanges various signals with an external device. Note that an output signal from the bubble sensor 114 or the like is taken into the controller 110 via the I / F unit 206. Further, the centrifugal pump 112, the clamp 122, and the like operate based on an instruction from the controller 110 via the I / F unit 206.

The communication unit 207 communicates with the communication unit 220 attached to the medical staff. The communication between the communication unit 207 and the communication unit 220 may be short-range wireless communication such as Bluetooth (registered trademark) or wireless communication using a wireless LAN such as Wi-Fi.

The above is an explanation of an example of the functional configuration of the controller 110. Note that the functional configuration shown in FIG. 2 is merely an example, and a new configuration may be added, or unnecessary configuration may be omitted as appropriate.

<3. Explanation of output signal from bubble sensor and bubble detection logic>
Next, an output signal from the bubble sensor 114 and bubble detection logic based on the output signal will be described. FIG. 3 is a diagram for explaining the output signal from the bubble sensor 114 and the bubble detection logic based on the output signal. The horizontal axis 3A in FIG. The elapsed time from the beginning is shown, and the vertical axis shows the output signal from the bubble sensor 114. Also, the horizontal axis 3B in FIG. 3 indicates the elapsed time since the bubble sensor 114 started detecting the bubble, and the vertical axis represents the unit time calculated based on the output signal from the bubble sensor 114. The change of the dispersion value is shown.

As shown in 3A of FIG. 3, the output signal from the bubble sensor 114 is constantly fluctuating, and the cause of the fluctuation is the decrease in the level of the output signal due to the passage of bubbles and the output signal accompanying various noises. And lowering the level. Among these, the level drop of the output signal due to the passage of the bubble is proportional to the volume of the bubble passing through, and when a relatively large bubble passes, the level drop of the output signal becomes large, When the bubbles are mixed and mixed and passed as a large group of small bubbles, the level of the output signal is small, but the level is repeatedly reduced in a short time.

On the other hand, the level reduction of the output signal due to various noises is relatively small and is similar to the level reduction that occurs when a large number of bubble groups pass, but it is characterized by a single occurrence.

For this reason, when detecting bubbles with high accuracy based on the output signal from the bubble sensor 114, the dispersion value per unit time of the output signal is monitored and relatively large bubbles pass. Therefore, when the dispersion value temporarily exceeds the predetermined value, and when the dispersion value exceeds the predetermined value for a certain period of time due to the passage of many small bubbles, it is effective to determine that the bubble is a bubble. You can say that. Further, since the level drop of the output signal is small and occurs once, it can be said that it is effective to determine that the noise is large when the increase in the variance value is small.

For this reason, in the extracorporeal circulation apparatus 100 according to the present embodiment, when the variance value per unit time is sequentially calculated based on the output signal of the bubble sensor 114, and the variance value exceeds the first reference value, the bubble It is determined that bubble generation has started, calculation of the volume of bubbles is started, and when the value falls below the second reference value, it is determined that generation of bubbles has stopped, and calculation of the volume of bubbles is terminated.

In the example of 3B in FIG. 3, at time t _1, the dispersion value exceeds the first reference value, at time t _2, the dispersion value is lower than the second reference value. Thus in the time period P _1, determines that the bubble has occurred, to extract the time zone P _1, in the time period P _1, the output signal to calculate the area of a region lower than a predetermined threshold value that Thus, a value (V ₁₁ ) corresponding to the volume of the bubbles is calculated (3A in FIG. 3).

Similarly, at time t ₃ , the variance value is greater than the first reference value, at time t ₄ , the variance value is less than the second reference value, and at time t ₅ and time t ₇ , the variance value is the first value, respectively. It exceeds the reference value, and at time t ₆ and time t ₈ , the variance value is below the second reference value. Therefore, it is determined that bubbles are generated in the time zones P ₂ , P ₃ , and P ₄ . As a result, the time zones P ₂ , P ₃ , and P ₄ are extracted and the area corresponding to the volume of the bubble (V ₁₂₎ is calculated by calculating the area of the region where the output signal is lower than the predetermined threshold value in the time zone. To V ₂₀ ).

On the other hand, the decrease in the level of the output signal shown in V _n1 and V _n2 (3A in FIG. 3), the dispersion value per unit time at that time does not exceed the first reference value (3B in FIG. 3), and bubbles are generated. It is not determined that it is in progress, but is determined to be due to noise.

<4. Change over time of accumulated value of bubble volume>
Next, processing of values (V ₁₁ to V ₂₀ ) corresponding to the volume of the bubbles calculated by determining that the bubbles are present will be described.

In general, the bubbles mixed in the blood sent to the subject are singly divided into large-volume bubbles that adversely affect the subject and, as described above, are divided and the volume of each bubble is small. However, if the bubble that adversely affects the subject by flowing continuously for a certain period of time (that is, if the group of divided bubbles is returned to the state of one mass before the division, the subject is adversely affected. Bubbles with a large volume).

Of these, the former bubble can be dealt with by monitoring the drop in the level of the output signal of the bubble sensor 114. On the other hand, for the latter bubble, it is important to calculate the cumulative value of the volume of the bubble and monitor the change in the cumulative value over time.

FIG. 4 is a diagram showing a time change of the accumulated value obtained by accumulating the calculation results when the value corresponding to the volume of the bubble is calculated in FIG.

In FIG. 4, the horizontal axis indicates the elapsed time from the start of detection of bubbles by the bubble sensor 114, and the vertical axis indicates the cumulative value ΣV. When the bubble sensor 114 starts detecting bubbles, zero is input to the cumulative value ΣV. However, when the time T ₁ (3A in FIG. 3) has elapsed, V ₁₁ is added and the time T 1 is added. _{when 2} (3A of FIG. 3) has _{elapsed, V 12} is added. Similarly, V ₁₃ to V ₂₀ are added every time the times T ₃ to T ₁₀ elapse.

Thereby, as shown in FIG. 4, the cumulative value ΣV gradually increases with the passage of time.

In addition, various operation | movement can be considered as operation | movement of the extracorporeal circulation apparatus 100 with respect to the time change of the cumulative value (SIGMA) V shown in FIG. For example, when the cumulative value ΣV reaches a predetermined value, the clamp 122 may be closed to stop blood feeding, or only an alarm may be output.

Further, when the degree of increase of the cumulative value ΣV per predetermined time reaches a predetermined value, the clamp 122 may be closed or an alarm may be output.

<5. Flow of bubble volume calculation process>
Next, the flow of the bubble amount calculation process by the bubble amount calculation unit 210 will be described with reference to FIG. FIG. 5 is a flowchart showing the flow (information processing method) of the bubble amount calculation process by the bubble amount calculation unit 210.

As shown in FIG. 5, in step S501, it is determined whether or not a first reference value for detecting bubbles and a second reference value for ending volume calculation have been set. If it is determined in step S501 that the first reference value and the second reference value are not set, the process waits until the setting is completed.

On the other hand, if it is determined that the first reference value and the second reference value have been set, the process proceeds to step S502. In step S502, acquisition of bubble data and storage in the storage unit 205 are started by starting reception of an output signal from the bubble sensor 114.

In step S503, calculation of a variance value per unit time is started for the received output signal from the bubble sensor 114.

In step S504, the calculated dispersion value per unit time is monitored and it is determined whether or not it exceeds the first reference value. If it is determined in step S504 that the value does not exceed the first reference value, the process proceeds to step S509.

On the other hand, if it is determined in step S504 that the calculated dispersion value per unit time exceeds the first reference value, the process proceeds to step S505, and the bubble volume is calculated from the time when the calculated value exceeds the first reference value. Start. Specifically, by calculating the area of the region where the output signal is lower than a predetermined threshold for the level drop of the output signal that occurs after the time when the first reference value is exceeded, a value corresponding to the volume of the bubble is obtained. calculate.

Further, the process proceeds to step S506, and the value corresponding to the bubble volume calculated in step S505 is added to the cumulative value ΣV.

Furthermore, in step S507, it is determined whether or not the dispersion value per unit time is less than the second reference value. If it is determined that the dispersion value is not less than the second reference value, the process returns to step S505, and the volume of the bubble is determined. Continue to calculate the value corresponding to.

On the other hand, if it is determined in step S507 that the dispersion value per unit time is lower than the second reference value, the process proceeds to step S508, the calculation of the value corresponding to the bubble volume is stopped, and the process proceeds to step S509.

In step S509, it is determined whether or not the extracorporeal circulation operation has been completed. If it is determined that the extracorporeal circulation operation has not been completed, the process returns to step S504 to continue monitoring the dispersion value per unit time.

On the other hand, if it is determined in step S509 that the extracorporeal circulation operation has ended, the bubble amount calculation process ends.

As is clear from the above description, the extracorporeal circulation device 100 according to the present embodiment is configured to sequentially calculate the dispersion value per unit time based on the output signal of the bubble sensor and monitor the dispersion value.

Furthermore, when the calculated variance value per unit time exceeds the first reference value and the level of the output signal of the bubble sensor is reduced, the level drop is caused by the passage of the bubble. It was judged that it was a thing and it was set as the structure which calculates the volume of a bubble. Further, the calculation of the bubble volume is stopped when the calculated dispersion value falls below the second reference value.

In this way, by adopting a configuration that monitors the dispersion value per unit time of the output signal of the bubble sensor, it is possible to clearly distinguish noise that is generated in a single shot and has a small level drop from a large number of bubble groups. It has become possible.

As a result, it was possible to accurately detect bubbles with a small volume to bubbles with a large volume.

[Second Embodiment]
In the first embodiment, the second reference value is provided. However, the present invention is not limited to this, and when the dispersion value per unit time becomes zero, the volume calculation is stopped. Also good.

In the first embodiment, the predetermined threshold (fixed value) is used to calculate the value corresponding to the volume of the bubble. However, the present invention is not limited to this, and the bubble is detected. It is also possible to calculate an average value of output signals in a non-period of time and use the average value (variable value) as a threshold value.

In the first embodiment, the bubble sensor that outputs a signal that lowers the level according to the size of the bubble is assumed. However, the present invention is not limited to this, and the level changes according to the size of the bubble. Any bubble sensor that outputs a signal may be used.

In the first embodiment, the dispersion value per unit time of the output signal is calculated as a parameter for determining a bubble. However, the present invention is not limited to this, and variations in the output signal are detected. Other parameters may be used as long as they are shown.

[Other Embodiments]
The present invention is not limited to the above-described embodiment, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, in order to make the scope of the present invention public, the following claims are attached.

Claims (8)

A circulation device that circulates the blood of a subject outside the body using a circulation circuit,
Detecting means arranged in the circulation circuit and outputting a signal whose level changes according to the size of each bubble mixed in the circulated blood;
A calculation means for sequentially calculating a variance value per unit time of the signal output from the detection means;
An extraction means for extracting a time zone from when the variance value per unit time calculated by the calculation means exceeds the first reference value to below the second reference value;
A circulating apparatus comprising: a determination unit that determines each level change included in the signal output from the detection unit in the time zone extracted by the extraction unit as a bubble. The calculation unit according to claim 1, further comprising: a calculation unit that calculates a cumulative value by accumulating values corresponding to the volume of each bubble calculated for each level change determined as a bubble by the determination unit. The described circulation device. The calculation unit calculates an area of a region lower than a predetermined threshold of the signal when a level change determined as the bubble occurs in the signal output by the detection unit, thereby calculating the bubble. The circulation device according to claim 2, wherein a value corresponding to the volume of is calculated. 4. The circulator according to claim 3, wherein when the accumulated value calculated by the calculating means reaches a predetermined value, the circulation of the blood is stopped. A control device that controls a circulation device that circulates the blood of a subject outside the body using a circulation circuit,
Receiving means for receiving the signal from the bubble sensor, which is arranged in the circulation circuit and whose level of the output signal changes according to the size of the bubble mixed in the circulated blood;
Calculating means for sequentially calculating a variance value per unit time of the signal received from the receiving means;
An extraction means for extracting a time zone from when the variance value per unit time calculated by the calculation means exceeds the first reference value to below the second reference value;
A control apparatus comprising: a determination unit that determines each level change included in the signal received from the reception unit in the time zone extracted by the extraction unit as a bubble. An information processing method in a control device for controlling a circulation device that circulates the blood of a subject outside the body using a circulation circuit,
A detection step that is arranged in the circulation circuit and outputs a signal that changes in level according to the size of each bubble mixed in the circulated blood;
A calculation step of sequentially calculating a variance value per unit time of the signal output in the detection step;
An extraction step for extracting a time zone from the time when the variance value per unit time calculated in the calculation step is higher than the first reference value to lower than the second reference value;
And a determination step of determining each level change included in the signal output in the detection step in the time zone extracted in the extraction step as a bubble. A program for causing a computer to function as each unit of the control device according to claim 5. A computer-readable recording medium storing a program for causing a computer to function as each unit of the control device according to claim 5.

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