JP5864766B2 - Signal processing device, medical device, and signal processing method - Google Patents

Description

  The present invention relates to a signal processing device that processes an output signal of a bubble detection device (bubble sensor), a medical device including the signal processing device, and a signal processing method in the signal processing device.

  Conventionally, in a medical device such as an extracorporeal circulation device or an infusion device, a bubble sensor for detecting bubbles contained in a liquid such as a priming solution or an infusion solution is attached to a tube, and an output signal from the bubble sensor is signaled. By processing with the processing device, the presence / absence of bubbles, the size of bubbles, and the like are determined.

  In general, a bubble sensor attached to a tube includes a signal transmission unit that transmits signals such as ultrasonic waves and light, and a signal reception unit that receives a signal transmitted through the tube. The signal receiving unit detects a decrease in the received signal level that occurs in this manner (see, for example, Patent Document 1).

JP-A-6-178808

  However, the position and direction on the tube where the bubble sensor is mounted are not always the same. For example, the bubble sensor may be mounted on a vertically disposed tube, or on a horizontally disposed tube. It may be attached to. When mounted on a horizontally arranged tube, the tube may be mounted so that the tube is sandwiched from above and below by the signal transmitter and signal receiver, or it may be sandwiched from the left and right. It may be installed as shown.

  Here, the bubbles in the tube are not always in the same shape, and the shape usually changes depending on the direction in which the liquid flows. This will be described with reference to FIG.

  FIG. 7 is a diagram illustrating a state in which the shape of the bubble is deformed in accordance with the direction in which the liquid flows. 7a of FIG. 7 has shown the case where a mode that the bubble sensor was mounted | worn with the tube arrange | positioned perpendicularly | vertically was seen from right above. Moreover, 7b of FIG. 7 has shown the state where the bubble sensor was mounted | worn so that a signal transmission part and a signal reception part may be inserted | pinched from the upper and lower sides with respect to the tube arrange | positioned horizontally. Further, 7c in FIG. 7 shows a state in which the bubble sensor is mounted from the side so that the signal transmission unit and the signal reception unit are sandwiched from the left and right with respect to the horizontally arranged tubes.

  As is apparent from 7a-7c in FIG. 7, even if the bubble size (volume) is the same, the shape of the detected bubble (ultrasonic wave or The width of attenuation of signals such as light (Wa, Wb, Wc)) is different.

  As a result, the areas where the signal is attenuated by a predetermined level or more (areas Sa, Sb, Sc obtained by integrating the widths Wa, Wb, Wc in the direction in which the liquid flows, that is, the direction in which the signal is transmitted. In the case of a signal processing device that determines the presence / absence of bubbles, the size of bubbles, etc., by monitoring the bubble cross-sectional area obtained by projecting bubbles toward a plane perpendicular to The problem of deteriorating occurs.

  The present invention has been made in view of the above problems, and an object thereof is to improve the determination accuracy when determining the presence or absence of bubbles, the size of bubbles, and the like.

In order to achieve the above object, a signal processing apparatus according to the present invention comprises the following arrangement. That is,
A signal processing device that is connected to a bubble sensor attached to a tube through which a liquid flows and processes an output signal output from the bubble sensor,
An acquisition means for acquiring, from the bubble sensor, a reception signal obtained by receiving a signal transmitted in a direction intersecting a direction in which the liquid flows through the tube;
By acquiring an inclination signal for calculating the inclination angle of each axis of the bubble sensor from the bubble sensor, the inclination angle of each axis of the bubble sensor is calculated, and based on the calculated inclination angle of each axis. Determining means for determining a mounting state of the bubble sensor with respect to the tube;
A calculation unit that calculates the size of the bubble by using the reception signal acquired by the acquisition unit and a correction value that is determined in advance according to the wearing state determined by the determination unit;

  According to the present invention, it is possible to improve the determination accuracy when determining the presence or absence of bubbles, the size of bubbles, and the like.

It is a figure which shows an example of the whole structure of the extracorporeal circulation apparatus 100 which is a medical device provided with the signal processing apparatus which concerns on the 1st Embodiment of this invention. 3 is a diagram illustrating an example of a functional configuration of a controller 110 of the extracorporeal circulation device 100. FIG. It is a figure for demonstrating the structure and mounting state of the bubble sensor. It is a figure for demonstrating the outline | summary of the process in the inclination measurement part. It is a figure for demonstrating the outline | summary of the process in the inclination measurement part. 6 is a diagram illustrating a relationship between an inclination angle of the bubble sensor 114 and a bubble cross-sectional area calculated by a bubble cross-section calculating unit 212. FIG. It is a flowchart which shows the flow of the bubble determination process in the signal processing part 210. FIG. It is a figure which shows a mode that the shape of a bubble deform | transforms with the direction through which a liquid flows.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In each of the following embodiments, an extracorporeal circulation device will be described as an example of a medical device to which the signal processing device according to the present invention is applied. However, the medical device to which the signal processing device according to the present invention is applied is an extracorporeal device. The medical device is not limited to the circulation device, and may be another medical device.

[First Embodiment]
<1. Overall configuration of extracorporeal circulation device>
1A of FIG. 1 is a diagram illustrating an example of an overall configuration of an extracorporeal circulation device 100 including a signal processing device according to a first 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. In the extracorporeal circulation apparatus 100, after performing the priming operation, the blood of the subject 130 is circulated extracorporeally using this circulation circuit.

  Here, the priming operation refers to an operation of removing the 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).

  The extracorporeal circulation device 100 includes a controller 110 that functions as a signal processing device, a drive motor 111, a centrifugal pump 112, an oxygenator 113, an oxygen supply source 117, a catheter (venous side) 119, and a catheter (arterial side). 120, a bubble sensor 114, a branch line 118, a blood filter 116, and a flow sensor 115. 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 sends 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 the priming liquid flowing in the circulation circuit during the priming 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 is configured to include, for example, an ultrasonic transceiver, and measures the blood flow in the circulation circuit.

  The branch line 118 switches the flow path of the circulation circuit. Specifically, when 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. 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 outside the body 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 controls the extracorporeal circulation operation and the priming operation in the extracorporeal circulation device 100. In the controller 110, for example, the drive motor 111 is controlled to drive the centrifugal pump 112, the oxygenator 113 is controlled to perform a gas exchange operation, or the bubble sensor 114 is controlled to output from the bubble sensor 114. A signal is acquired, and the flow rate sensor 115 is controlled to acquire a flow rate value.

  In the present embodiment, the bubble sensor 114 includes a signal transmission unit 231, a signal reception unit 232, an X-axis acceleration detection unit 233X, a Y-axis acceleration detection unit 233Y, and a Z-axis acceleration detection unit 233Z, as shown in FIG. . The signal transmission unit 231 and the signal reception unit 232 are arranged so as to sandwich the tube through which the priming liquid flows, and the signal reception unit 232 receives the signal transmitted from the signal transmission unit 231 and transmitted through the tube and the inside thereof. A signal corresponding to is output as a bubble signal. The direction in which the signal transmission unit 231 transmits a signal (an ultrasonic signal or an optical signal) is a direction that intersects the direction in which the priming liquid flows in the tube. The X-axis acceleration detection unit 233X, the Y-axis acceleration detection unit 233Y, and the Z-axis acceleration detection unit 233Z constitute an attitude sensor that detects the attitude of the bubble sensor 114. The attitude sensor can have various other configurations. In another example, the attitude sensor can include a three-axis gyro.

  The controller 110 determines the presence / absence of bubbles, the size of bubbles, and the like based on the bubble signal output from the bubble sensor 114. Here, in the present embodiment, the posture or inclination angle of the bubble sensor 114 attached to the tube is determined using the posture signal or acceleration signal output from the bubble sensor 114 when determining the presence / absence of bubbles and the size of bubbles. And the bubble size is corrected based on the calculated posture or inclination angle. Details of these processes relating to bubbles in the controller 110 will be described later.

  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 under the control of the controller 110, and the priming liquid circulates in the circulation circuit over a plurality of rounds. Bubbles in the circulation circuit are discharged from the bubble discharge port or the like with this circulation. At this time, bubbles in the circulation circuit are detected by the bubble sensor 114, and the controller 110 determines whether or not there are bubbles contained in the circulation circuit and the size of the bubbles based on the detection result of the bubble sensor 114. .

  Here, in the controller 110, when the result of the determination satisfies a predetermined criterion, the priming operation is terminated. At the end of this, the controller 110 notifies the user that the priming operation has ended using a display (not shown), a speaker (not shown), or the like. The user who receives the notification of the end of the priming operation switches the branch line 118 and constructs a circulation circuit that passes through the body of the subject 130 as shown in 1A of FIG. 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. This process from blood removal to blood delivery is repeated, and the blood of the subject 130 is circulated extracorporeally.

  The above is the description of the overall configuration of the extracorporeal circulation device 100 according to the present embodiment and an example of the flow of the 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 includes a display unit 203, an operation unit 202, a storage unit 201, an I / F unit 206, a timer unit 204, and a control unit 205 as functional configurations.

  The display unit 203 is realized by a display such as a monitor, for example, and displays various types of information for the user. The operation unit 202 is realized by various buttons, for example, and inputs an instruction from the user. Part or all of the display unit 203 and the operation unit 202 may be realized as a touch panel, for example.

  The storage unit 201 is realized by, for example, a hard disk and stores various types of information. It is assumed that a conversion table 221 that is referred to when executing processing in the signal processing unit 210 described later is stored in the storage unit 201.

  The I / F unit 206 exchanges various signals with an external device. The output signal (bubble signal, acceleration signal) from the bubble sensor 114 including the signal transmission unit 231, the signal reception unit 232, and the X-axis acceleration detection unit 233 X to Z-axis acceleration detection unit 233 Z is the I / F unit 206. Via the controller 110. The timer unit 204 measures various times.

  The control unit 205 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and the ROM stores a program for realizing the above-described cardiopulmonary assist operation. It shall be.

  The ROM stores a program for processing an output signal (bubble signal, posture signal (acceleration signal)) from the bubble sensor 114, and is executed by the CPU, so that the control unit 205 outputs a signal. It functions as the processing unit 210.

  The signal processing unit 210 includes an inclination measurement unit 211 that calculates an attitude (inclination angle) of the bubble sensor 114 based on an attitude signal (acceleration signal) among output signals from the bubble sensor 114, and an output from the bubble sensor 114. A bubble cross-sectional area calculating unit 212 that calculates the bubble cross-sectional area based on the bubble signal and corrects the calculated bubble cross-sectional area using the attitude (inclination angle) of the bubble sensor 114. The signal processing unit 210 determines the presence / absence of bubbles, the size of bubbles, and the like using the corrected bubble cross-sectional area. Details of each part of the signal processing unit 210 and a flow of bubble determination processing in the signal processing unit 210 will be described later.

  The above is 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. For example, the storage unit 201 (hard disk or the like) is not necessarily provided and may be omitted.

<3. Bubble sensor configuration and orientation (wearing state)>
Next, the configuration and posture (mounted state) of the bubble sensor 114 will be described. FIG. 3 is a diagram for explaining the configuration and mounting state of the bubble sensor 114. Here, in this embodiment, in the extracorporeal circulation device 100, the bubble sensor 114 and the tube are arranged so as to be in any one of the three postures exemplified by 3a, 3b, and 3c in FIG. Assumed.

  First, the configuration of the bubble sensor 114 will be described. As shown to 3a-3c of FIG. 3, the bubble sensor 114 is provided with the opening part for letting a tube pass, and the inner wall face (not shown) which forms the said opening part closely_contact | adheres to the outer peripheral surface of a tube Is configured to do.

  The bubble sensor 114 is configured to transmit a signal (an ultrasonic signal or an optical signal) in the direction of a dotted arrow, and a signal transmission unit 231 (not shown in FIG. 3) is arranged on the starting point side of the dotted arrow. In addition, a signal receiver 232 (not shown in FIG. 3) is disposed on the end point side of the dotted arrow.

  Further, the bubble sensor 114 includes an acceleration detector 233X (not shown in FIG. 3) for detecting acceleration in the X-axis direction and an acceleration detector 233Y (not shown in FIG. 3) for detecting acceleration in the Y-axis direction. ) And an acceleration detector 233Z (not shown in FIG. 3) for detecting acceleration in the Z-axis direction. The acceleration detected by each acceleration detection unit is transmitted to the controller 110 as an acceleration signal via a connection cable (not shown).

  Next, the posture of the bubble sensor 114 attached to the tube will be described. Here, the posture of the bubble sensor 114 attached to the tube can also be understood as the attachment state of the bubble sensor 114 to the tube. 3a of FIG. 3 has shown the mode that the bubble sensor 114 was mounted | worn with respect to the tube into which a liquid flows vertically along a thick arrow. In this case, the signal is transmitted in the horizontal direction.

  On the other hand, 3b in FIG. 3 is a direction that is substantially perpendicular to the direction in which the liquid flows in the horizontal direction along the thick arrow so that a signal is transmitted in the horizontal direction. A state in which the bubble sensor 114 is attached is shown.

  Further, 3c in FIG. 3 shows a state in which the bubble sensor 114 is mounted so that a signal is transmitted in the vertical direction to the tube in which the liquid flows in the horizontal direction along the thick arrow.

  As described above, the bubble sensor 114 is provided with the acceleration detection units 233X to 233Z that detect the accelerations in the X-axis direction, the Y-axis direction, and the Z-axis direction. By calculating how much the bubble sensor 114 is inclined with respect to the (perpendicular direction), the mounting state can be determined.

  For example, if the calculation result shows that the X-axis tilt angle with respect to the horizontal direction is 0 degrees, the Y-axis tilt angle with respect to the horizontal direction is 0 degrees, and the Z-axis tilt angle with respect to the horizontal direction is 90 degrees, It can be determined that the bubble sensor 114 is attached to the tube in the attachment state indicated by 3a.

  In addition, as a result of calculation, when the inclination angle of the X axis with respect to the horizontal direction is calculated as 0 degree, the inclination angle of the Y axis with respect to the horizontal direction is calculated as 90 degrees, and the inclination angle of the Z axis with respect to the horizontal direction is calculated as 0 degrees, 3 can be determined that the bubble sensor 114 is attached to the tube in the attachment state shown in 3b.

  Furthermore, as a result of calculation, when the inclination angle of the X axis with respect to the horizontal direction is calculated as 90 degrees, the inclination angle of the Y axis with respect to the horizontal direction is calculated as 0 degrees, and the inclination angle of the Z axis with respect to the horizontal direction is calculated as 0 degrees, It can be determined that the bubble sensor 114 is attached to the tube in the attachment state shown in 3c of FIG.

<4. Processing in tilt measurement unit>
Next, an outline of processing in the inclination measuring unit will be described. 4A and 4B are diagrams for explaining an outline of processing in the inclination measurement unit. As described above, the bubble sensor 114 is configured to detect the acceleration in each of the X-axis direction, the Y-axis direction, and the Z-axis direction, and each axis is inclined several times with respect to the horizontal direction, for example. Can be calculated. However, in the following description, only the inclination angle of the X axis will be described for the sake of simplicity.

  FIG. 4A shows how much gravity is dispersed in the X-axis direction when the X-axis of the bubble sensor 114 is inclined by θ degrees with respect to the horizontal direction.

  As can be seen from FIG. 4A, when gravitational acceleration = g, when tilted by θ degrees with respect to the horizontal direction, the gravitational acceleration in the X-axis direction is g × sin θ.

  On the other hand, FIG. 4B shows the relationship between the gravitational acceleration detected in the X-axis direction of the bubble sensor 114 and the inclination angle of the X-axis from the horizontal direction. As can be seen from FIG. 4B, when the gravitational acceleration when the X-axis is inclined 90 degrees from the horizontal direction is g, the bubble sensor is detected when 0.5 g of gravitational acceleration is detected by the acceleration detection unit 233X in the X-axis direction. It can be determined that the X axis 114 is inclined by 30 degrees with respect to the horizontal direction.

  As described above, the inclination measurement unit 211 obtains the acceleration signal of the X-axis acceleration detection unit 233X of the bubble sensor 114, and is obtained when the acceleration signal and the inclination angle of the X-axis from the horizontal direction are 90 degrees. By calculating the ratio to the acceleration signal to be obtained, the tilt angle of the X axis with respect to the horizontal direction can be calculated.

  With respect to the Y-axis and the Z-axis, the tilt angle can be calculated based on the acceleration signal from the acceleration detectors 233Y and 233Z by the same calculation method.

<5. Processing in the bubble cross section calculation unit>
Next, an outline of processing in the bubble cross-sectional area calculation unit 212 will be described. FIG. 5 is a diagram showing the relationship between the inclination angle of the bubble sensor 114 and the bubble cross-sectional area when bubbles having the same volume flow through the tube. As shown in 5a of FIG. 5, when the tilt angle of the X axis with respect to the horizontal direction is 0 degree, the tilt angle of the Y axis with respect to the horizontal direction is 0 degree, and the tilt angle of the Z axis with respect to the horizontal direction is 90 degrees, The bubble cross-sectional area Sa calculated by the bubble cross-sectional area calculation unit 212 based on the bubble signal from 232 (the range in which the bubble signal is attenuated by a predetermined level or more. That is, toward a plane perpendicular to the direction in which the signal is transmitted. It is not necessary to correct the bubble area when the bubble is projected.

  On the other hand, as shown in FIG. 5b, the X-axis tilt angle with respect to the horizontal direction was calculated as 0 degree, the Y-axis tilt angle with respect to the horizontal direction was calculated as 90 degrees, and the Z-axis tilt angle with respect to the horizontal direction was calculated as 0 degrees. In this case, the bubble cross-sectional area Sb calculated by the bubble cross-sectional area calculation unit 212 based on the bubble signal from the signal receiving unit 232 (the range in which the bubble signal is attenuated by a predetermined level or more, that is, perpendicular to the direction in which the signal is transmitted) The area of the bubbles when the bubbles are projected toward a smooth surface) is larger than the bubble cross-sectional area Sa shown in 5a of FIG. For this reason, correction is performed according to the following equation using the correction value α.

Corrected bubble cross-sectional area Sb ′ = α × Sb where α <1
In addition, as shown in FIG. 5c, when the X-axis tilt angle with respect to the horizontal direction is 90 degrees, the Y-axis tilt angle with respect to the horizontal direction is 0 degrees, and the Z-axis tilt angle with respect to the horizontal direction is 0 degrees, The bubble cross-sectional area Sc calculated by the bubble cross-sectional area calculation unit 212 based on the bubble signal from the receiving unit 232 (the range in which the bubble signal is attenuated by a predetermined level or more. That is, on the plane perpendicular to the direction in which the signal is transmitted) The area of the bubble when the bubble is projected toward the head) is smaller than the bubble cross-sectional area Sa shown in 5a of FIG. For this reason, correction is performed according to the following equation using the correction value β.
Corrected bubble cross-sectional area Sc ′ = β × Sc where β> 1
As described above, the bubble cross-sectional area calculation unit 212 corrects the calculated bubble cross-sectional area according to the mounting state of the bubble sensor 114.

<6. Flow of bubble determination processing in signal processing unit>
Next, the flow of bubble determination processing in the signal processing unit 210 will be described. FIG. 6 is a flowchart showing the flow of bubble determination processing in the signal processing unit 210.

  When the bubble determination process is started, in step S601, the acquisition of the bubble signal output from the signal receiving unit 232 of the bubble sensor 114 is started.

  In step S602, it is determined whether a bubble has been detected based on the captured bubble signal. Specifically, it is determined whether or not the captured bubble signal has fallen below a predetermined level.

  If it is determined in step S602 that bubbles are not detected (that is, the incorporated bubble signal has not dropped below a predetermined level), the process waits until bubbles are detected.

  On the other hand, if it is determined in step S602 that bubbles have been detected (that is, the incorporated bubble signal has dropped below a predetermined level), the process proceeds to step S603.

  In step S603, the bubble cross-sectional area is calculated. Specifically, when the state in which the captured bubble signal has decreased to a predetermined level or lower continues, the width that has decreased to a predetermined level or lower (the length in the direction orthogonal to the signal transmission direction) ) Is integrated in the liquid flow direction to calculate the bubble cross-sectional area.

  In step S604, acceleration signals output from the acceleration detection units 233X to 233Z of the bubble sensor 114 are received. In step S605, the inclination angle of each axis with respect to the horizontal direction is calculated based on the acceleration signal received in step S604.

  In step S606, the posture or mounting state of the bubble sensor 114 is determined based on the calculation result of the tilt angle in step S605, and the bubble cross-sectional area calculated in step S603 is corrected based on the determination result. For example, as a result of calculating the inclination angle in step S605, the bubble cross-sectional area calculated in step S603 is determined depending on which posture or attachment state of the bubble sensor 114 is 3a-3c in FIG. (In the case of 3b in FIG. 3, the correction value α is applied. In the case of 3c in FIG. 3, the correction value β is applied. In the case of 3a in FIG. 3, the correction value = 1 is applied.) .

  In step S607, bubble determination is performed using the bubble cross-sectional area corrected in step S606. Specifically, it is determined whether or not the corrected bubble cross-sectional area is greater than or equal to a predetermined threshold, and if it is determined that the corrected bubble cross-sectional area is greater than or equal to the predetermined threshold, it is determined that there is a bubble. If it is determined that there is a bubble, the size of the bubble is further classified based on the corrected bubble cross-sectional area (for example, the size of the bubble is classified into large, medium, and small). .

  In step S608, it is determined whether an instruction to end the bubble determination process has been input. If it is determined that no end instruction has been input, the process returns to step S602. On the other hand, if it is determined that an instruction to end the bubble determination process has been input, the process proceeds to step S609, the capture of the bubble signal output from the signal receiving unit 232 of the bubble sensor 114 is terminated, and the bubble determination process is terminated. .

  As is apparent from the above description, in this embodiment, the bubble sensor is provided with the acceleration detection units 233X to 233Z, and the inclination angle of the bubble sensor is calculated to determine the posture or mounting state of the bubble sensor with respect to the tube. It was. Furthermore, the bubble cross-sectional area calculated based on the bubble signal from the bubble sensor is corrected based on the determined wearing state.

  As a result, it is possible to improve the determination accuracy when determining the presence / absence of bubbles and the size of bubbles based on the cross-sectional area of bubbles.

[Second Embodiment]
In the first embodiment, when calculating the inclination angle of the bubble sensor 114, the acceleration sensor is provided in the bubble sensor. However, the present invention is not limited to this, and other detection means may be used. Also good.

  In the first embodiment, the bubble sensor 114 defines three axes (X axis, Y axis, Z axis), and the acceleration detection unit is provided in the X axis direction, the Y axis direction, and the Z axis direction. However, this invention is not limited to this, The structure provided in any one axis | shaft or two axes | shafts may be sufficient.

  Furthermore, in the second embodiment, 3a to 3c in FIG. 3 are listed as examples of the mounting state of the bubble sensor 114, but the present invention is not limited to this, and other mounting states (for example, X in the horizontal direction) A mounting state in which the tilt angle in the axial direction is 30 degrees, the tilt angle in the Y-axis direction is 0 degrees, and the tilt angle in the Z-axis direction is 0 degrees may be employed. In this case, since the correction value α or β for correcting the bubble cross-sectional area varies depending on the inclination angle of each axis, the correction value corresponding to each mounting state is stored in the storage unit as the conversion table 221. You may make it store. The correction value α or β at this time may be obtained experimentally or by calculation (simulation or the like).

[Third Embodiment]
In the first embodiment, the processing related to individual bubbles has been described as the bubble determination processing in the signal processing unit 210. However, the present invention is not limited to this, and a plurality of results using the processing related to individual bubbles can be used. You may comprise so that a process may be performed about a bubble.

  For example, the cumulative bubble cross-sectional area may be calculated by cumulatively adding the corrected bubble cross-sectional areas. Further, the calculated cumulative bubble cross-sectional area may be compared with a predetermined threshold value.

  Or you may comprise so that the variation | change_quantity per unit time of the cumulative bubble cross-sectional area calculated by carrying out cumulative addition of the corrected bubble cross-sectional area may be calculated. In this case, the calculated change amount may be compared with a predetermined threshold value.

  Or you may comprise so that the number of the magnitude | sizes of each bubble divided based on the corrected bubble cross-sectional area may be counted, and the variation | change_quantity per unit time may be calculated.

[Fourth Embodiment]
In the first embodiment, the corrected bubble cross-sectional area is output, but the present invention is not limited to this. For example, the bubble volume may be calculated based on the corrected bubble cross-sectional area. Note that the relationship between the corrected bubble cross-sectional area and the bubble volume may be stored as a conversion table 221 in a storage unit, and the bubble volume may be calculated using the conversion table 221. The conversion table at this time may be obtained experimentally or by calculation (simulation or the like).

[Other Embodiments]
The above is an example of a typical embodiment of the present invention, but the present invention is not limited to the embodiment described above and shown in the drawings, and can be appropriately modified and implemented within the scope not changing the gist thereof. .

  This application claims priority based on Japanese Patent Application No. 2012-199843 filed on September 11, 2012, the entire contents of which are incorporated herein by reference.

  100: extracorporeal circulation device, 111: drive motor, 112: centrifugal pump, 113: artificial lung, 114: bubble sensor, 115: flow sensor, 116: blood filter, 117: oxygen supply source, 118: branch line, 119: catheter , 120: catheter, 130: subject

Claims (9)

A signal processing device for processing an output signal output from a bubble sensor attached to a tube through which a liquid flows,
An acquisition means for acquiring, from the bubble sensor, a reception signal obtained by receiving a signal transmitted in a direction intersecting a direction in which the liquid flows through the tube;
By acquiring an inclination signal for calculating the inclination angle of each axis of the bubble sensor from the bubble sensor, the inclination angle of each axis of the bubble sensor is calculated, and based on the calculated inclination angle of each axis. Determining means for determining a mounting state of the bubble sensor with respect to the tube;
Calculating means for calculating the size of the bubble by using the received signal acquired by the acquiring means and a correction value determined in advance according to the wearing state determined by the determining means. A signal processing device. The calculating means includes
Based on the reception signal acquired by the acquisition means, the cross-sectional area of the bubble is calculated when the bubble is projected onto a surface substantially orthogonal to the transmitted signal, the calculated cross-sectional area, and the determination means The signal processing apparatus according to claim 1, wherein the bubble size is calculated by using a correction value determined in advance according to the mounting state determined in step 1.   The calculation means calculates the cross-sectional area of the bubble by calculating the continuous range when the state in which the reception signal is reduced to a predetermined level or lower is continuous. The signal processing apparatus according to claim 2, wherein:   The calculating means calculates the continuous range by integrating a length in which the received signal is reduced below a predetermined level in a direction in which the liquid flows. The signal processing apparatus according to claim 3. The inclination signal is an acceleration signal of an acceleration detection unit that detects acceleration of each axis of the bubble sensor,
The said determination means calculates the inclination angle of each axis | shaft of the said bubble sensor by calculating the ratio of the acceleration of each said axis | shaft with respect to the gravitational acceleration of a perpendicular direction, Either of the Claims 1 thru | or 4 characterized by the above-mentioned. 2. The signal processing device according to item 1.   The said calculating means calculates the magnitude | size of the said bubble based on the conversion table which prescribed | regulated the relationship with the determined mounting state and a correction value, The one of Claims 1 thru | or 5 characterized by the above-mentioned. A signal processing device according to 1.   A medical device comprising the signal processing device according to claim 1. A signal processing method in a signal processing apparatus that is connected to a bubble sensor attached to a tube through which a liquid flows and processes an output signal output from the bubble sensor,
An acquisition step of acquiring from the bubble sensor a reception signal obtained by receiving a signal transmitted in a direction intersecting a direction in which the liquid flows through the tube;
By acquiring an inclination signal for calculating the inclination angle of each axis of the bubble sensor from the bubble sensor, the inclination angle of each axis of the bubble sensor is calculated, and based on the calculated inclination angle of each axis. A determination step of determining a mounting state of the bubble sensor with respect to the tube;
A calculation step of calculating a bubble size by using the reception signal acquired in the acquisition step and a correction value determined in advance according to the wearing state determined in the determination step. A signal processing method. A signal processing device for processing a signal from a bubble sensor attached to a tube through which a liquid flows,
The bubble sensor includes a signal transmission unit and a signal reception unit arranged so as to sandwich the tube, and the signal reception unit receives and receives the signal transmitted from the signal transmission unit and transmitted through the tube and the inside thereof. Output a signal according to the
The processor is
Obtaining means for obtaining a signal output from the bubble sensor;
Determining means for determining the attitude of the bubble sensor;
Calculation means for calculating the size of bubbles in the liquid flowing through the tube based on the signal acquired by the acquisition means and the posture of the bubble sensor determined by the determination means. A signal processing device.

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