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WO2024135522A1 - Dispositif et procédé de commande de système de circulation sanguine, et programme - Google Patents

Dispositif et procédé de commande de système de circulation sanguine, et programme Download PDF

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Publication number
WO2024135522A1
WO2024135522A1 PCT/JP2023/044815 JP2023044815W WO2024135522A1 WO 2024135522 A1 WO2024135522 A1 WO 2024135522A1 JP 2023044815 W JP2023044815 W JP 2023044815W WO 2024135522 A1 WO2024135522 A1 WO 2024135522A1
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WIPO (PCT)
Prior art keywords
blood
flow rate
reservoir
control unit
stored
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English (en)
Japanese (ja)
Inventor
敏夫 辻
智 曽
拓矢 木下
秀暢 高橋
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Hiroshima University NUC
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Hiroshima University NUC
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
    • A61M1/36—Other treatment of blood in a by-pass of the natural circulatory system, e.g. temperature adaptation, irradiation ; Extra-corporeal blood circuits
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
    • A61M60/10—Location thereof with respect to the patient's body
    • A61M60/104—Extracorporeal pumps, i.e. the blood being pumped outside the patient's body
    • A61M60/109—Extracorporeal pumps, i.e. the blood being pumped outside the patient's body incorporated within extracorporeal blood circuits or systems

Definitions

  • the present invention relates to a control device, control method, and program for a blood circulation system.
  • Blood circulation systems that circulate blood between the body and outside the body, such as the cardiopulmonary bypass (CPB) system that replaces the functions of the heart and lungs, are used during surgery.
  • CPB cardiopulmonary bypass
  • clinical engineers perform blood flow rate control, reservoir blood volume control, oxygen gas concentration control, oxygen gas flow rate control, temperature control, myocardial fluid injection, vital sign monitoring, equipment information monitoring, operation recording, etc.
  • the adjustment of blood flow rate and the adjustment of reservoir blood volume are closely related, and long-term training is required to adjust these simultaneously.
  • the patient is connected to a reservoir and a blood pump via tubes attached to the arterial and venous sides.
  • flow rate adjustment means such as occluders are placed on the arterial and venous tubes.
  • the blood flow rate is controlled by opening and closing the occluders that constrict the arterial and venous tubes.
  • the amount of blood stored in the reservoir is determined by the difference between the amount of arterial blood flowing into the reservoir and the amount of venous blood flowing out of the reservoir. Since the amount of blood stored in the reservoir corresponds to the amount of blood in the patient's heart and lungs, if the amount of blood stored in the reservoir becomes unstable, it can lead to unintended fluctuations in the patient's blood pressure, putting the patient's life at risk. Furthermore, an extreme drop in the amount of blood stored in the reservoir can cause an air embolism, which can cause serious damage to the patient. Therefore, clinical engineers are required to control the blood flow rate while paying attention to the amount of blood stored in the reservoir.
  • Patent Document 1 blood circulation systems that control blood flow rate have been proposed.
  • the blood withdrawal flow rate which is the flow rate of blood withdrawn from the human body
  • the blood feed flow rate which is the flow rate of blood transported to the human body by the blood feed pump
  • the blood feed flow rate is controlled in conjunction with the blood withdrawal flow rate to be within a specific range.
  • the blood feed flow rate is controlled based on predetermined conditions to adjust the reservoir level.
  • the blood sending flow rate is adjusted when the liquid level in the reservoir exceeds a threshold value, and control of the blood sending flow rate based on the blood removal flow rate and the blood sending flow rate based on the liquid level in the reservoir are performed independently. More specifically, while the liquid level in the reservoir exceeds the threshold value and liquid level adjustment is being performed, the blood sending flow rate is increased or decreased under preset conditions to adjust the liquid level in the reservoir to be within a predetermined range. Then, when the liquid level in the reservoir falls below the threshold value, the liquid level adjustment is terminated.
  • the blood sending flow rate is not normally adjusted based on the liquid level in the reservoir, but is adjusted only when a predetermined threshold is exceeded. Furthermore, the blood sending flow rate adjustment for adjusting the liquid level in the reservoir is performed based on conditions set independently of the normal blood sending flow rate control. Therefore, flexible control according to the ever-changing amount of stored blood in the reservoir is not possible, and it is difficult to stably control the amount of stored blood and the blood sending flow rate when the amount of stored blood changes suddenly due to a sudden change in the amount of blood removed by vents, suction, etc. other than the blood removal line from the vein.
  • the present invention was made in consideration of the above circumstances, and aims to provide a control device, control method, and program for a blood circulation system that can stably control the blood flow rate and the amount of blood stored in the reservoir.
  • a control device for a blood circulation system comprises: a reservoir control unit that controls the amount of blood stored in a reservoir that stores the removed blood; a blood flow rate control unit for controlling a blood flow rate sent from the reservoir to a human body,
  • the reservoir control unit includes: Calculating a correction flow rate, which is a correction value of the target blood sending flow rate, based on the target stored blood volume and the measured stored blood volume;
  • the blood flow rate control unit includes:
  • the blood supply flow rate controller has a reference flow rate calculation model that outputs a reference flow rate, which is an estimated value of an appropriate blood supply flow rate, based on the target blood supply flow rate and the corrected flow rate, which are inputs, and a blood supply flow rate controller that receives the reference flow rate as an input and outputs a manipulated variable for controlling the blood supply flow rate.
  • the reference flow rate calculation model is a model of the control operation of the blood flow rate by a clinical engineer. This may also be the case.
  • the transfer function of the reference flow rate calculation model is expressed by the following formula: This may also be the case.
  • the blood flow rate controller further comprises: A PID controller with feedforward. This may also be the case.
  • the reservoir control unit further includes: An I-PD controller, This may also be the case.
  • I controller C eL,I and PD controller C eL,PD Using the above formula, This may also be the case.
  • the target blood sending flow rate is a blood withdrawal flow rate from the vein of the human body to the reservoir. This may also be the case.
  • the reservoir control unit measures the amount of stored blood based on images of the reservoir taken at predetermined time intervals. This may also be the case.
  • the control device for the blood circulation system includes: a centrifugal pump for pumping blood from the reservoir to the body; an occluder that is installed in a blood supply line connecting the centrifugal pump and the human body, and that adjusts the blood supply flow rate by constricting the blood supply line according to an opening degree of the occluder;
  • the blood feed flow rate control unit controls the blood feed flow rate by adjusting the opening degree of the occluder. This may also be the case.
  • the blood flow rate controller is a PID controller having feedforward, designed based on a model represented by the following equation: This may also be the case.
  • a method for controlling a blood circulation system includes the steps of: a blood supply flow rate sent from a reservoir that stores the removed blood to the human body is controlled based on a target blood supply flow rate and a correction flow rate that is a correction value of the target blood supply flow rate; The amount of stored blood is controlled by calculating the correction flow rate based on a target amount of stored blood in the reservoir and the measured amount of stored blood.
  • a program comprises: Computer, a blood feed flow rate control unit that controls the blood feed flow rate sent from a reservoir that stores the removed blood to the human body based on a target blood feed flow rate and a correction flow rate that is a correction value of the target blood feed flow rate; a reservoir control unit that calculates the correction flow rate based on a target stored blood volume of the reservoir and the measured stored blood volume, and controls the stored blood volume; Operate as.
  • the control device, control method, and program for the blood circulation system of the present invention adjust the blood sending flow rate by correcting the target blood sending flow rate based on the amount of stored blood in the reservoir, so that the blood sending flow rate and the amount of stored blood can be stably controlled.
  • FIG. 1 is a schematic diagram showing the configuration of an artificial heart-lung system according to an embodiment of the present invention.
  • FIG. 2 is a functional block diagram of a control device according to the embodiment.
  • FIG. 2 is a block diagram of a control device according to the embodiment.
  • FIG. 2 is a block diagram showing a configuration of a controlled object model according to the embodiment.
  • FIG. 2 is a schematic diagram showing the configuration of a simulated cardiopulmonary bypass system according to an experimental example.
  • FIG. 13 is a block diagram of a control device that does not have a reservoir control unit. 13 is a graph showing the results of an experimental example in which a glycerin solution was used as the perfusion fluid.
  • 8A and 8B are graphs showing evaluation function values of the experimental results in FIG. 7, in which FIG.
  • FIG. 8A is a graph showing evaluation function values of blood flow rate
  • FIG. 8B is a graph showing evaluation function values of pooled blood volume.
  • 13 is a graph showing the results of an experimental example in which a bovine blood solution was used as the perfusion fluid.
  • 1A and 1B are graphs showing the difference in evaluation function values depending on the perfusion fluid, where FIG. 1A is a graph showing the evaluation function value of the blood flow rate, and FIG. 1B is a graph showing the evaluation function value of the pooled blood volume.
  • 13 is a graph showing the results of an experimental example when a disturbance is applied.
  • 11A and 11B are graphs showing evaluation function values when an afterload variation is applied
  • FIG. 11B is a graph showing evaluation function values when a vent/suction disturbance is applied.
  • the blood circulation system according to the present invention is a system that circulates blood between the human body and outside the body, and there are no particular limitations on the parts to which it is applied or the purpose.
  • an artificial heart-lung system 1 is controlled as a blood circulation system.
  • the control device 10 controls the blood supply flow rate based on the blood withdrawal flow rate, and controls the amount of blood stored in the reservoir 51.
  • the heart-lung machine system 1 includes a blood removal tube 21, a suction line 22, a vent line 23, a blood supply tube 24, a blood removal side occluder 31, a blood supply side occluder 32, a blood removal flow rate sensor 41, a blood supply flow rate sensor 42, a stored blood volume sensor 43, a reservoir 51, a blood supply pump 52, and an artificial lung 53.
  • the heart-lung machine system 1 also includes a control device 10 that controls the blood supply flow rate and the stored blood volume.
  • the blood vessel removal tube 21 is connected to the human body (patient P) and the reservoir 51, and is a tube that sends blood removed from the vein of patient P to the reservoir 51.
  • the blood vessel removal tube 21 is, for example, a tube made of polyvinyl chloride.
  • the reservoir 51 is a container that stores blood sent through the blood vessel 21.
  • the reservoir 51 stores blood that is sucked (suctioned) by a pump to ensure a blood-free field of view during surgery, blood that is removed (vented) from inside the heart to prevent overstretching of the heart, etc.
  • the reservoir 51 is equipped with a filter (not shown) to remove these.
  • the amount of blood stored in the reservoir 51 is determined by the flow rate difference between the venous blood flow rate (outflow rate) flowing into the reservoir 51 and the arterial blood flow rate (outflow rate) flowing out of the reservoir 51.
  • the amount of stored blood corresponds to the amount of blood in the patient P's heart and lungs, so if the amount of stored blood becomes unstable, it will cause unintended fluctuations in the patient P's blood pressure, putting the patient P's life at risk. In addition, an extreme drop in the amount of stored blood may cause air embolism, which may cause serious damage to the patient P. Therefore, in this embodiment, in order to maintain the amount of stored blood within an appropriate range, the amount of stored blood calculated from the blood level in the reservoir 51 is controlled to be maintained at a target value.
  • the reservoir 51 in this embodiment is a hard shell type, and the control device 10 adjusts the blood sending flow rate based on the reservoir 51's liquid level to control the amount of stored blood in the reservoir 51.
  • the suction line 22 is a line that uses a pump (not shown) to suck up bleeding blood and send it to the reservoir 51 to ensure a bloodless field of view during surgery.
  • the suction line 22 is, for example, a polyvinyl chloride tube.
  • the vent line 23 is a line that sends blood drawn from the heart to the reservoir 51 in order to prevent overstretching of the heart.
  • the vent line 23 is, for example, a polyvinyl chloride tube.
  • the amount of blood sent to the reservoir 51 through the suction line 22 and vent line 23 varies depending on the circumstances of the surgery. Therefore, it is difficult to accurately measure the fluctuations in the stored blood volume due to these blood volumes. It is required that the stored blood volume and blood sending flow rate of the reservoir 51 be appropriately controlled according to such fluctuations in the amount of blood removed by suction and vent.
  • the blood supply tube 24 is a tube that connects the reservoir 51 and the blood supply pump 52, the blood supply pump 52 and the artificial lung 53, and the artificial lung 53 and the patient P.
  • the blood supply tube 24 is, for example, a tube made of polyvinyl chloride.
  • the blood supply pump 52 is connected to the reservoir 51 and the artificial lung 53 via the blood supply line 24, and sends blood stored in the reservoir 51 to the artificial lung 53.
  • the blood supply pump 52 in this embodiment is a centrifugal pump that has low risks of unintended pressure increases in the blood supply line 24, air embolism due to erroneous operation, and hemolysis due to prolonged use.
  • the artificial lung 53 is a device that exchanges gas between the carbon dioxide in the venous blood sent through the drainage vessel 21, the suction line 22, and the vent line 23 and the oxygen supplied by the artificial lung 53.
  • a publicly known artificial lung device can be used as the artificial lung 53.
  • the blood removal side occluder 31 is installed in the blood removal vessel 21 between the patient P and the reservoir 51, and adjusts the blood removal flow rate by narrowing the blood removal vessel 21 according to the opening degree.
  • the blood feed side occluder 32 is installed in the blood feed vessel 24 between the artificial lung 53 and the patient P, and adjusts the blood feed flow rate by narrowing the blood feed vessel 24 according to the opening degree.
  • the opening degree of the blood removal side occluder 31 is constant, and the blood feed flow rate is controlled by adjusting the opening degree of the blood feed side occluder 32 so as to follow the blood removal flow rate.
  • the relationship between the opening degree of the blood removal side occluder 31 and the blood supply side occluder 32 and the blood flow rate is measured in advance.
  • the control device 10 adjusts the opening degree of the occluders based on the measurement data acquired in advance to control the flow rate.
  • the blood removal flow rate sensor 41 is a sensor that is placed between the patient P and the blood removal side occluder 31 and measures the blood removal flow rate.
  • the blood sending flow rate sensor 42 is a sensor that is placed between the blood sending side occluder 32 and the patient P and measures the blood sending flow rate.
  • an ultrasonic sensor, an electromagnetic sensor, etc. can be used.
  • the retained blood volume sensor 43 is a sensor that measures the volume of retained blood in the reservoir 51.
  • Various sensors can be used as the retained blood volume sensor 43, such as a weight sensor that measures the volume of retained blood based on the weight of the reservoir 51, or a level sensor that measures the liquid level with a probe inserted into the reservoir 51.
  • the retained blood volume sensor 43 in this embodiment is a camera that can photograph the liquid level in the reservoir 51, and the control device 10 receives images of the reservoir 51 taken at predetermined time intervals by the camera that is the retained blood volume sensor 43, and measures the volume of retained blood in the reservoir 51.
  • the control device 10 calculates the amount of stored blood based on an image of the reservoir 51 captured by the camera that is the stored blood volume sensor 43, but this is not limited to the above.
  • the stored blood volume sensor 43 may include a calculation unit that calculates the amount of stored blood based on the captured image, and transmit the calculated amount of stored blood to the control device 10.
  • the control device 10 is, for example, a computer device, and as shown in the functional block diagram of FIG. 2, includes a blood flow rate control unit 101, a reservoir control unit 102, a blood removal flow rate measurement unit 103, a blood flow rate measurement unit 104, a pump control unit 105, a memory unit 106, a display unit 107, and an input unit 108.
  • the control device 10 includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and controls the operation of each part of the artificial heart-lung system 1.
  • the control device 10 loads various operating programs and data stored in the ROM, memory unit 106, etc. of the control device 10 into the RAM and operates the CPU, thereby realizing each function of the control device 10 shown in FIG. 2.
  • the control device 10 operates as a blood supply flow rate control unit 101, a reservoir control unit 102, a blood removal flow rate measurement unit 103, a blood supply flow rate measurement unit 104, and a pump control unit 105.
  • the blood feed flow control unit 101 has a reference flow calculation model that outputs a reference flow rate, which is an estimate of an appropriate blood feed flow rate, based on the input target blood feed flow rate and corrected flow rate, and a blood feed flow rate controller that takes the reference flow rate as input and outputs an operation amount for controlling the blood feed flow rate.
  • the blood feed flow rate control unit 101 controls the blood feed flow rate based on the target blood feed flow rate and the corrected flow rate, which is a corrected value of the target blood feed flow rate.
  • the target blood feed flow rate is, for example, the blood withdrawal flow rate from the vein of the patient P to the reservoir 51.
  • the corrected flow rate is a correction value that corrects the target blood feed flow rate in order to control the amount of blood stored in the reservoir 51, and is calculated by the reservoir control unit 102.
  • the blood feed flow rate is controlled by adjusting the opening of the blood feed side occluder 32.
  • the reservoir control unit 102 calculates a correction flow rate based on the measured amount of stored blood in the reservoir 51 so that the amount of stored blood becomes a predetermined target value (target stored blood volume) set by a clinical engineer.
  • the reservoir control unit 102 then controls the amount of stored blood by correcting the target blood sending flow rate, which is the input to the blood sending flow rate control unit 101, with the calculated correction flow rate.
  • the blood removal flow rate measuring unit 103 measures the blood removal flow rate in the blood removal vessel 21 based on the output of the blood removal flow rate sensor 41.
  • the measured blood removal flow rate is the blood flow rate from the vein of the patient P to the reservoir 51, and is the blood removal flow rate that does not take into account blood removal by venting and suction.
  • the blood flow rate measurement unit 104 measures the blood flow rate in the blood supply vessel 24 based on the output of the blood flow rate sensor 42.
  • the pump control unit 105 controls the operation of the blood feed pump 52. Specifically, the rotation speed of the blood feed pump 52, which is a centrifugal pump, is controlled to adjust the flow rate of blood sent from the reservoir 51 to the artificial lung 53.
  • the rotation speed of the blood feed pump 52 is controlled, for example, based on the blood removal flow rate, which is the target value for the blood feed flow rate, and the blood feed flow rate is adjusted by the rotation speed of the blood feed pump 52 and the opening degree of the blood feed side occluder 32.
  • the rotation speed of the blood feed pump 52 is kept constant, and the blood feed flow rate to the patient P is adjusted by the blood feed side occluder 32. There is no limit to the rotation speed of the blood feed pump 52 in controlling the amount of blood stored in the reservoir 51.
  • the storage unit 106 is a non-volatile memory such as a hard disk or flash memory, and stores various control programs, measurement data, etc.
  • the display unit 107 is a display device provided in the control device 10, which is a computer device, and is, for example, a liquid crystal panel.
  • the display unit 107 displays the amount of blood stored in the reservoir 51, the blood sending flow rate, etc., related to the operating state of the artificial heart-lung system 1.
  • the input unit 108 is an input device for inputting instructions to start and end the operation of the control device 10, the target blood volume to be stored in the reservoir 51, etc.
  • the input unit 108 is a keyboard, touch panel, mouse, etc. provided on the control device 10.
  • the configuration of the blood feed flow rate control unit 101 is not particularly limited as long as it controls the blood feed flow rate based on a target blood feed flow rate and a corrected flow rate.
  • the blood feed flow rate control unit 101 according to this embodiment is a PID controller.
  • the configuration of the reservoir control unit 102 is not particularly limited as long as it outputs a corrected flow rate calculated based on a target stored blood volume and a stored blood volume to the blood feed flow rate control unit 101 to control the stored blood volume.
  • the reservoir control unit 102 according to this embodiment is an I-PD controller.
  • Occ (t) is the opening of the blood sending occluder
  • R is the resistance of the entire flow path of the artificial heart-lung system 1 excluding the flow path of the occluder
  • ⁇ R o is the resistance of the occluder flow path
  • Q 0 is the blood flow rate when the occluder opening is 100%
  • a and K are parameters expressing the relationship between the occlusion diameter of the blood sending blood vessel and the opening of the blood sending occluder
  • L is the dead time
  • T is a first-order time constant.
  • the nonlinear feedforward controller which is the blood flow rate controller, is designed based on a nonlinear static model and a linear dynamic model including the nonlinear control system shown in the following equation.
  • O cc m (s) is the reference occluder opening
  • Q m (t) is the reference flow rate
  • G m (s) is a model of the control action of a skilled clinical engineer who controls the blood sending side occluder 32, and the behavior is defined by an arbitrary time constant ⁇ .
  • the control device 10 includes a blood feed flow rate control unit 101 and a reservoir control unit 102 to achieve automatic control of the opening degree of the blood feed side occluder 32.
  • the blood feed flow rate control unit 101 has a nested structure with the reservoir control unit 102 to simultaneously adjust the blood feed flow rate and the amount of blood stored in the reservoir 51.
  • the reservoir controller 102 adjusts the opening of the blood sending side occluder 32 to make the stored blood volume Y L (s) in the reservoir 51 coincide with the target stored blood volume R L (s).
  • the blood sending flow rate controller 101 adjusts the blood sending occluder opening O cc (s) to make the blood sending flow rate Q (s) follow the reference flow rate Q m (s).
  • the blood flow rate controller of the blood flow rate control unit 101 is a two-degree-of-freedom model matching controller C e (s) consisting of a feedforward controller and a feedback PID controller, and is defined by the following transfer function: where K P , e , K I , e , and K D , e are the proportional gain, integral gain, and differential gain of the blood flow rate control unit 101 , respectively.
  • an I-PD controller C eL (s) is used which is composed of an I controller C eL , I (s) and a PD controller C eL , PD (s) given by the following transfer function: where K P , L , K I , L , and K D , L are the proportional gain, integral gain, and differential gain of the reservoir control unit 102, respectively.
  • R L (s) is the target stored blood volume
  • Y L (s) is determined by the integral of the difference between the blood removal flow rate and the blood supply flow rate (the 1/s element on the right side of FIG. 3).
  • the blood flow control system for cardiopulmonary bypass surgery there are two disturbance factors.
  • One is the blood volume D(s) due to venting and suction, and the vent/suction blood volume D(s) increases the amount of blood removed.
  • the other is the afterload variation D y (s), which is the resistance when sending blood to the patient P.
  • the vent/suction blood volume D(s) and the afterload variation D y (s) are factors that cause the reservoir blood volume RL to fluctuate.
  • the influence of the vent/suction blood volume D(s) and the afterload variation D y (s) approaches zero over time.
  • FIG. 5 shows an experimental simulated cardiopulmonary bypass system 2 consisting of a CPB circuit and the control device 10.
  • the body of a patient P is simulated using a soft shell reservoir 81 and a liquid tank 82.
  • the other settings are configured similarly to those of a clinical CPB system.
  • the CPB circuit was connected by a blood removal tube 21 and a blood supply tube 24, which are polyvinyl chloride tubes.
  • the measured flow rate and the captured image are input to the control device 10, which generates a control signal for the blood supply occluder 32 (made by Senko Medical Industries Co., Ltd.; HAS-RH200).
  • a Hoffman clamp 83 and a pressure gauge 84 are installed in the blood supply vessel 24 between the blood supply flow rate sensor 42 and the liquid tank 82.
  • venting and suction are simulated by transferring the perfusion fluid from the soft shell reservoir 81 to the reservoir 51 (made by Senko Medical Industries Co., Ltd.; HVR-4NFP) using a roller pump 85 (made by JMS Co., Ltd.; MF-02).
  • Glycerin solution and bovine blood solution were used as perfusion fluids.
  • the glycerin solution was made by mixing glycerin and red powder dye (Dianix Red 200%, manufactured by Mitsubishi Chemical Corporation) with water.
  • the viscosity of the glycerin solution measured with a viscometer (SV-10, manufactured by A&D Co., Ltd.) was 2.84 mPa ⁇ s at 18.8°C.
  • the bovine blood solution was made by mixing a bovine red blood cell solution, the anticoagulant sodium citrate (Funakoshi Co., Ltd.), and physiological saline.
  • the viscosity of the bovine blood solution was 2.66 mPa ⁇ s at 24.3°C.
  • the parameters of the controller described above were determined as follows.
  • the parameters of the nonlinear static model (Equations (1) and (4)) were set based on the inventors' previous research (H. Takahashi, Z. Soh, and T. Tsuji, "Steady-state model of pressure-flow characteristics modulated by occluders in cardiopulmonary bypass systems," IEEE Access, vol.8, pp. 220962-220972, Dec. 2020, doi:10.1109/ACCESS.2020.3043470).
  • the gain parameters of the PID controller for the blood flow rate control unit 101 and the I-PD controller for the reservoir control unit 102 were set by the pole placement method.
  • the configuration of the control system without the reservoir control unit 102 is configured as a system in which C eL (s) related to the reservoir control unit 102 and its related inputs and outputs are deleted from the block diagram of FIG. 3, as shown in FIG. 6.
  • glycerin solution or bovine blood solution was injected into the reservoir 51 and used as the perfusion fluid. This confirmed the effect of the perfusion fluid's characteristics on control accuracy.
  • the maximum blood withdrawal flow rate and maximum blood supply flow rate were adjusted to 3.0 L/min using a Hoffman clamp 86 and a blood supply pump 52, which is a centrifugal pump (rotation speed: 1700 to 2200 rpm).
  • the target blood volume stored in the reservoir 51 was set to 0.45 L.
  • the experimental protocol was designed to anticipate operations at the initiation and withdrawal of CPB. Specifically, in the CPB initiation process, the blood flow rate was increased from 0.0 L/min to 3.0 L/min over 100 seconds. After that, the blood flow rate was maintained at 3.0 L/min for 100 seconds. Then, in the CPB withdrawal process, the blood flow rate was reduced from 3.0 L/min to 1.0 L/min over 100 seconds, after which the blood flow rate was maintained for 50 seconds, and finally the blood flow rate was instantly reduced to 0.0 L/min to stop the perfusion. Using this experimental protocol, experiments were performed eight times for each of the six configuration patterns and perfusion fluids.
  • vent/suction disturbances The experimental protocol is designed to simulate afterload fluctuations and disturbances due to venting and suction (hereinafter referred to as vent/suction disturbances).
  • vent/suction disturbances can easily occur due to changes in the blood circulation of patient P, misalignment of the arterial cannulation, bending of the blood circuit, etc. This changes the relationship between the opening of the blood supply side occluder 32 and the blood supply flow rate.
  • the simulated heart-lung machine 2 is first stabilized with a blood flow rate of 1.5 L/min and a blood volume of 0.45 L stored in the reservoir 51. Then, a Hoffman clamp 83 is used to create a pressure drop of 150 mmHg upstream of the liquid tank 82 for 100 seconds to simulate fluctuations in afterload. This results in a flow rate fluctuation of approximately 0.5 L/min.
  • perfusion fluid was flowed directly into the reservoir 51 at 0.35 L/min for 100 seconds to simulate vent/suction disturbances.
  • Each disturbance simulation experiment was performed five times for each of the six configuration patterns.
  • the effectiveness of the control device 10 according to the present embodiment was evaluated in terms of the following two aspects. Specifically, the evaluation was performed using the blood flow rate tracking accuracy JQ and the blood volume adjustment accuracy JL of the reservoir 51, which correspond to the following two equations:
  • J Q is the mean absolute error between the reference flow rate Q m (i) and the measured blood flow rate Q(i).
  • J L is the mean absolute error between the target pooled blood volume and the measured pooled blood volume.
  • the pooled blood volume is measured by image recognition based on an image captured by a camera.
  • the percentage error for the target blood delivery flow rate and the target pooled blood volume was calculated using the following formula.
  • the evaluation function values were compared between each configuration pattern using multiple comparison tests using the Tukey method.
  • the significance level was set at p ⁇ 0.05.
  • Statistical analysis was performed using SPSS (registered trademark) software version 22.0.
  • Example 7 shows an example of the results of a perfusion process experiment (Experiment 1) using a glycerin solution.
  • the CPB initiation process was started 50 seconds after the start of the experiment, and the blood flow rate was increased from 0.0 to 3.0 L/min in 100 seconds.
  • the CPB weaning process was started 250 seconds after the start of the experiment, and the blood flow rate was decreased to 0.0 L/min in 100 seconds.
  • the clinical engineer operated only the blood removal side occluder 31, and the blood transfer side occluder 32 was automatically controlled by the control device 10 according to this embodiment.
  • FIG. 8A compares the mean absolute error JQ of blood flow, which indicates the accuracy of tracking the blood feed flow rate to the blood removal flow rate, between the case with (right side) and the case without (left side) the reservoir control unit 102.
  • Each box plot represents the mean absolute error JQ obtained by performing eight trials of the perfusion process experiment with each configuration pattern.
  • the mean absolute error is JQ ⁇ 0.13 L/min, which corresponds to a percentage error of the target blood flow rate JQ % ⁇ 5.84%.
  • the three box plots in Fig. 8(A) represent three configuration patterns of the blood flow control unit 101 consisting of a feedforward controller, a feedback controller, and a controller including both feedforward and feedback.
  • JQ was significantly higher (p ⁇ 0.01). This result suggests that the tracking accuracy JQ can be improved by incorporating a nonlinear feedforward controller in the control device 10 not including the reservoir control unit 102.
  • FIG. 8B shows a comparison of the mean absolute error JL , which indicates the ability to adjust the amount of stored blood, with and without the reservoir control unit 102.
  • the significant difference in JL with and without the reservoir control unit 102 indicates that the control device 10 can effectively maintain the amount of stored blood in the reservoir 51.
  • Figure 9 shows an example of experimental results when a bovine blood solution was used as the perfusion fluid in a system equipped with a reservoir control unit 102.
  • a bovine blood solution was used as the perfusion fluid in a system equipped with a reservoir control unit 102.
  • Figure 7 it can be seen that the blood supply flow rate follows the blood removal flow rate, and the amount of stored blood is kept almost constant.
  • 10A and 10B show a comparison of the evaluation function values when a glycerin solution is used as the perfusate with those when a bovine blood solution is used.
  • Fig. 11 shows an example of the results of a disturbance experiment (Experiment 2), i.e., an experiment simulating afterload variation and vent/suction disturbance.
  • Example 2 i.e., an experiment simulating afterload variation and vent/suction disturbance.
  • the disturbance was applied between 50 and 150 seconds.
  • FIG. 12(A) and (B) show the difference in the evaluation function value depending on the presence or absence of the reservoir control unit 102, where FIG. 12(A) shows the case where afterload variation was applied, and FIG. 12(B) shows the case where vent/suction disturbance was applied.
  • FIG. 12(A) and (B) show data derived from all data related to each trial of this experiment.
  • control device 10 equipped with the reservoir control unit 102 can maintain the amount of stored blood in the reservoir 51 at the target stored blood amount while controlling the blood sending flow rate.
  • the target stored blood volume in the reservoir 51 and the correction flow rate calculated based on the stored blood volume are used to correct the target blood sending flow rate to adjust the blood sending flow rate, so the blood sending flow rate and stored blood volume can be stably controlled.
  • the target stored blood volume can be stably maintained without causing large fluctuations in the stored blood volume.
  • control device 10 measures the amount of stored blood by performing image recognition on images of the reservoir 51 captured at a predetermined time interval. This makes it possible to measure the amount of stored blood with a simple configuration without modifying the reservoir 51 or adding elements.
  • the blood feed flow rate control unit 101 is a PID controller
  • the reservoir control unit 102 is an I-PD controller. This simplifies the configuration of the blood feed flow rate control unit 101 and the reservoir control unit 102, making it possible to design them easily.
  • the blood feed flow rate control unit 101 in this embodiment includes a feedforward function. This allows for precise control of the blood feed flow rate and the amount of stored blood.
  • the control device 10 in this embodiment does not control the blood removal flow rate, but this is not limited to the above.
  • the control device 10 may control the blood removal flow rate by adjusting the opening of the blood removal side occluder 31.
  • control method of the blood circulation system according to the above embodiment can be realized using a normal computer system.
  • a computer program for controlling the blood feed flow rate and the stored blood volume according to the above embodiment can be distributed via a network such as the Internet, and the computer program can be installed on a computer, causing the computer device to function as a control device that controls the above blood feed flow rate and the stored blood volume.
  • the present invention is suitable for use in control devices for blood circulation systems. It is particularly suitable for use in control devices where there are variations in the amount of blood drawn, such as afterload variations, venting, and suction.
  • Cardiopulmonary bypass system 2. Simulated cardiopulmonary bypass system, 10.
  • Control device 101. Blood supply flow rate control unit, 102. Reservoir control unit, 103. Blood removal flow rate measurement unit, 104. Blood supply flow rate measurement unit, 105. Pump control unit, 106. Memory unit, 107. Display unit, 108. Input unit, 21. Blood removal vessel, 22. Suction line, 23. Vent line, 24. Blood supply vessel, 31. Blood removal side occluder, 32. Blood supply side occluder, 41. Blood removal flow rate sensor, 42. Blood supply flow rate sensor, 43. Reservoir, 51. Reservoir, 52. Blood supply pump, 53. Artificial lung, 81. Soft shell reservoir, 82. Liquid tank, 83, 86. Hoffman clamp, 84. Pressure gauge, 85. Roller pump, P. Patient

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Abstract

L'invention concerne un dispositif de commande (10) conçu pour un système de circulation sanguine et comprenant : une unité de commande de réservoir (102) qui commande la quantité de sang stockée dans un réservoir destiné à stocker du sang prélevé ; et une unité de commande de débit d'administration de sang (101) qui commande le débit d'administration de sang depuis le réservoir vers un corps humain. L'unité de commande de réservoir (102) calcule un débit de correction, qui est une valeur de correction d'un débit d'administration de sang cible, sur la base d'une quantité de sang stockée cible et d'une quantité de sang stockée mesurée. L'unité de commande de débit d'administration de sang (101) comprend : un modèle de calcul de débit de référence qui délivre un débit de référence, qui est une valeur estimée d'un débit d'administration de sang approprié, sur la base du débit d'administration de sang cible et du débit corrigé en tant qu'entrées ; et un dispositif de commande de débit d'administration de sang qui délivre une quantité de fonctionnement pour commander le débit d'administration de sang à l'aide du débit de référence en tant qu'entrée. Ceci permet une correction constante du débit d'administration de sang cible sur la base de la quantité de sang stockée, ce qui permet de maintenir de manière stable la quantité de sang stockée cible sans fluctuations significatives de la quantité de sang stockée.
PCT/JP2023/044815 2022-12-23 2023-12-14 Dispositif et procédé de commande de système de circulation sanguine, et programme Ceased WO2024135522A1 (fr)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09154935A (ja) * 1995-10-03 1997-06-17 Terumo Corp 血液リザーバー、送血用器具および送血装置
JP2016043261A (ja) * 2014-08-20 2016-04-04 泉工医科工業株式会社 血液循環システム

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09154935A (ja) * 1995-10-03 1997-06-17 Terumo Corp 血液リザーバー、送血用器具および送血装置
JP2016043261A (ja) * 2014-08-20 2016-04-04 泉工医科工業株式会社 血液循環システム

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