Gas exchange system
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-02-02
- Publication Date
- 2026-08-13
Smart Images
Figure JP2026003524_13082026_PF_FP_ABST
Abstract
Description
Gas exchange system
[0001] The present disclosure relates to a gas exchange system.
[0002] For example, when it is necessary to temporarily replace the cardiopulmonary function of a patient during cardiac surgery, extracorporeal circulation is performed to circulate the patient's blood outside the body using an extracorporeal circulation system having a cardiopulmonary bypass device or the like. For example, among cardiac surgeries, various reconstructive surgeries such as valvuloplasty and vascular bypass may be performed with the patient's heart stopped. At this time, since the heart stops during the surgery, the heart and lungs are bypassed by an extracorporeal cardiopulmonary device installed outside the body, and gas exchange and blood circulation of the blood are ensured outside the body, so that cardiac surgery can be safely performed. In addition, it is also used for treatment (ECMO) using an extracorporeal circulation circuit with an artificial lung and a pump by temporarily replacing a part of the patient's cardiopulmonary function for a medium to long term. Examples of the extracorporeal circulation system used in these cases are disclosed in Japanese Patent Application Laid-Open No. 2007-14504.
[0003] The extracorporeal circulation system includes an artificial lung that performs gas exchange between blood and an oxygen-containing gas. The artificial lung has a gas exchange membrane. Inside the artificial lung, a blood flow path through which blood flows and a gas flow path through which an oxygen-containing gas flows are partitioned by a gas exchange membrane (hollow fiber membrane). In order to prevent blood components from leaking into the gas flow path, the gas exchange membrane is hydrophilically treated on the membrane surface or the like as necessary to have antithrombotic properties. On the other hand, although the hollow fiber membrane itself basically has hydrophobic properties, surface treatments such as hydrophobic treatment and hydrophilic treatment are performed according to the physical properties of the hollow fiber membrane used. [[ID=A]] [[ID=B]]
[0004] Japanese Patent Application Laid-Open No. 2007-14504
[0005] Prolonged use of an artificial lung can lead to deterioration of the gas exchange membrane, causing it to lose its hydrophobicity. This allows proteins from the blood to enter the pores, making the membrane partially hydrophilic. As a result, plasma, the liquid component of blood, can leak into the gas phase, a phenomenon known as plasma leakage. Plasma leakage refers to the phenomenon where plasma, a component of blood, leaks into the inside (gas phase) of the gas exchange membrane through micropores in the hollow fiber membrane that forms the gas exchange membrane. Plasma leakage reduces the gas exchange performance of the artificial lung, necessitating replacement of the artificial lung. Therefore, preventing plasma leakage is desirable.
[0006] This disclosure aims to solve the problems described above.
[0007] (1) An aspect of the present disclosure is a gas exchange system comprising: an artificial lung having a blood channel for flowing blood, a gas channel for flowing oxygen-containing gas, and a gas exchange membrane, and performing gas exchange with the blood via the gas exchange membrane; a pressure control valve provided on a gas discharge line for discharging gas from the gas channel of the artificial lung; a pressure sensor for detecting the pressure in the gas channel; and a control unit for controlling the pressure control valve so that the pressure in the gas channel is within a predetermined pressure range. With such a configuration, the pressure in the gas channel, which is the gas phase side inside the artificial lung, is adjusted to be within a predetermined pressure range, and plasma leaks can be prevented by preventing the outflow of liquid to the gas phase side due to deterioration of the gas exchange membrane with pressure to the liquid phase side.
[0008] (2) In the gas exchange system described in item (1) above, the control unit may control the pressure control valve so that the pressure in the gas flow path becomes the target pressure. With such a configuration, plasma leaks can be prevented more effectively.
[0009] (3) In the gas exchange system described in item (1) or (2) above, the pressure sensor may be provided in a gas line that communicates with the gas flow path of the artificial lung. With such a configuration, pressure detection in the gas flow path can be achieved with a simple configuration.
[0010] (4) In the gas exchange system described in item (3) above, the gas line on which the pressure sensor is provided may be the gas discharge line. With this configuration, the pressure in the gas flow path of the artificial lung is lower on the outlet side than on the inlet side. Therefore, by providing a pressure sensor in the discharge line, the pressure in the gas flow path can be suitably adjusted to a pressure that can prevent plasma leakage.
[0011] (5) In the gas exchange system described in item (4) above, the pressure control valve may be provided in the gas discharge line. With this configuration, pressure detection and pressure control of the gas flow path can be realized with a simple configuration.
[0012] According to this disclosure, since the pressure in the gas flow path, which is the gas phase side inside the artificial lung, is adjusted to a predetermined pressure range, plasma leakage can be prevented by preventing the outflow of liquid to the gas phase side due to deterioration of the gas exchange membrane by applying pressure to the liquid phase side.
[0013] Figure 1 is a schematic diagram of the extracorporeal circulation system. Figure 2 is a schematic diagram of the artificial lung. Figure 3 is a schematic diagram of the gas exchange section. Figure 4 is a block diagram of the gas mixing device. Figure 5 is an operation flow diagram of the gas exchange system in pressure adjustment mode.
[0014] The extracorporeal circulation system 10 shown in Figure 1 is used to circulate a patient's blood outside the body. The extracorporeal circulation system 10 comprises a pump drive unit 12, a blood pump 14, a control unit 16, an artificial lung 18, and a gas mixing device 20.
[0015] The pump drive unit 12 is a drive unit for rotating the blood pump 14. The pump drive unit 12 has a motor 13. The motor 13 generates a rotational driving force for rotating the blood pump 14. A magnetic coupling unit (not shown) is attached to the motor 13. The magnetic coupling unit can magnetically couple with the impeller provided on the blood pump 14. The pump drive unit 12 is controlled by a control unit 16.
[0016] The blood pump 14 is detachable from the pump drive unit 12. The blood pump 14 is a pump for circulating blood within the extracorporeal circulation circuit. The blood pump 14 is a centrifugal pump. A blood withdrawal catheter 22 is connected to the blood inlet port 141 of the blood pump 14. Blood is introduced from the human body (HM) to the blood pump 14 via the blood withdrawal catheter 22. One end of a relay tube 24 is connected to the blood outlet port 142 of the blood pump 14. The other end of the relay tube 24 is connected to the blood inlet port 30a of the artificial lung 18. The blood that flows out from the blood outlet port 142 of the blood pump 14 is introduced into the artificial lung 18 via the relay tube 24.
[0017] The artificial lung 18 performs gas exchange with the blood. As shown in Figure 2, the artificial lung 18 consists of, for example, a housing 26 and a gas exchange unit 28. The housing 26 has a blood inlet port 30a, a blood outlet port 30b, a gas introduction port 32a, and a gas discharge port 32b. The downstream end of the relay tube 24 is connected to the blood inlet port 30a. A blood delivery catheter 34 is connected to the blood outlet port 30b. The artificial lung 18 may also be equipped with a heat exchange unit if necessary. In this case, a heat exchange unit may be provided before and after the gas exchange unit 28 as needed, and ports may be provided to supply and discharge heated fluid (water) to the heat exchange unit.
[0018] The gas exchange section 28 is a hollow fiber membrane layer provided inside the housing 26. As shown in Figure 3, the gas exchange section 28 has a gas exchange membrane 29. In this embodiment, the gas exchange membrane 29 is composed of a large number of hollow fiber membranes 290. A blood flow channel 36 for blood flow is formed on the outside of the hollow fiber membrane 290. A large number of micropores 292 are formed in the wall portion 291 that constitutes each hollow fiber membrane 290. The hollow fiber membrane 290 is subjected to hydrophobic or hydrophilic treatment as needed, but when performing antithrombotic treatment with hydrophilic properties, the treatment agent is adjusted so that it does not reach the micropores 292. A gas flow channel 38 for oxygen-containing gas is formed on the inside of the hollow fiber membrane 290. Gas exchange takes place between the blood flowing in the blood flow channel 36 and the oxygen-containing gas flowing in the gas flow channel 38 by the gas exchange membrane 29. Specifically, oxygen is supplied to the blood and carbon dioxide is removed from the blood via the gas exchange membrane 29.
[0019] In Figure 1, blood is introduced from the relay tube 24 through the blood inflow port 30a to the gas exchange unit 28 of the artificial lung 18. In the gas exchange unit 28, the gas exchange described above takes place. The blood that has undergone gas exchange flows out from the blood outflow port 30b of the artificial lung 18 and is returned to the human body (HM) via the blood delivery catheter 34.
[0020] The artificial lung 18 is supplied with oxygen-containing gas through a gas supply line 40. The gas supply line 40 is a tube for supplying oxygen-containing gas to the artificial lung 18 and is connected to the gas inlet port 32a of the artificial lung 18. The lumen of the gas supply line 40 communicates with the gas flow path 38 inside the artificial lung 18. A gas outlet line 42 is connected to the gas outlet port 32b. The gas outlet line 42 is a tube for discharging gas (carbon dioxide-containing gas) from the gas flow path 38 inside the artificial lung 18 to the outside of the artificial lung 18. The lumen of the gas outlet line 42 communicates with the gas flow path 38 inside the artificial lung 18.
[0021] The gas mixing device 20 mixes oxygen gas and air to produce an oxygen-containing gas, which is a mixed gas with an appropriately adjusted oxygen concentration. The oxygen gas is supplied from the oxygen supply unit 44. The air is supplied from the air supply unit 46. The oxygen supply unit 44 is, for example, an oxygen supply pipe installed in a medical facility. The oxygen supply unit 44 may also be an oxygen cylinder filled with oxygen gas. The air supply unit 46 is, for example, an air supply pipe installed in a medical facility. The air supply unit 46 may also be an air cylinder filled with compressed air. The gas mixing device 20 can set the flow rate of the oxygen-containing gas supplied to the artificial lung 18 and the oxygen concentration in the oxygen-containing gas. The gas mixing device 20 supplies the generated oxygen-containing gas to the artificial lung 18 via the gas supply line 40. In this embodiment, the gas exchange system 50 is configured by the artificial lung 18 and the gas mixing device 20.
[0022] A pressure sensor 52 (hereinafter also referred to as the "inlet pressure sensor 52") is provided in the gas supply line 40. The inlet pressure sensor 52 is located near the gas introduction port 32a of the artificial lung 18. Therefore, the inlet pressure sensor 52 can detect the pressure on the inlet side of the gas flow path 38 inside the artificial lung 18.
[0023] The gas discharge line 42 is equipped with a pressure sensor 54 (hereinafter also referred to as the "outlet pressure sensor 54") and a pressure control valve 56. The outlet pressure sensor 54 is located near the gas discharge port 32b of the artificial lung 18. Therefore, the outlet pressure sensor 54 can detect the pressure on the outlet side of the gas flow path 38 within the artificial lung 18. The pressure control valve 56 is located downstream of the outlet pressure sensor 54 in the gas discharge line 42. The pressure control valve 56 can adjust its valve opening based on the input opening command signal.
[0024] As shown in Figure 4, the gas mixing device 20 comprises an input unit 60, a display unit 62, and a control device 64. The input unit 60 is a user interface that accepts input operations from the user. By operating the input unit 60, the user can set various parameters (flow rate of mixed gas supplied to the artificial lung 18, oxygen concentration, artificial lung outlet pressure, etc.). The display unit 62 displays the set parameters.
[0025] The control device 64 has an arithmetic unit 66 and a storage unit 68. The arithmetic unit 66 is composed of a processor, such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), i.e., a processing circuit.
[0026] The arithmetic unit 66 includes an acquisition unit 70, a determination unit 72, and a control unit 74. The acquisition unit 70, the determination unit 72, and the control unit 74 can be realized by the execution of a program stored in the storage unit 68 by the arithmetic unit 66. At least a portion of the acquisition unit 70, the determination unit 72, and the control unit 74 may be realized by integrated circuits such as ASICs (Application Specific Integrated Circuits) and FPGAs (Field-Programmable Gate Arrays). Alternatively, at least a portion of the acquisition unit 70, the determination unit 72, and the control unit 74 may be composed of electronic circuits including discrete devices.
[0027] The acquisition unit 70 acquires information from the inlet pressure sensor 52 and the outlet pressure sensor 54. The determination unit 72 makes various determinations based on the information from the inlet pressure sensor 52 and the outlet pressure sensor 54 (details will be described later). The control unit 74 controls the pressure control valve 56 so that the pressure in the gas flow path 38 (Figure 3) is within a predetermined pressure range based on the information from the inlet pressure sensor 52 and the outlet pressure sensor 54. The control unit 74 also controls the flow control valve (not shown) so that the mixed gas supplied to the artificial lung 18 reaches a set flow rate based on information from a pressure sensor and a flow rate sensor (not shown) provided in the gas mixing device 20.
[0028] The storage unit 68 is composed of a volatile memory (not shown) and a non-volatile memory (not shown). Examples of volatile memory include RAM (Random Access Memory). The volatile memory is used as the working memory of the processor and temporarily stores data necessary for processing or calculation. Examples of non-volatile memory include ROM (Read Only Memory) and flash memory. The non-volatile memory is used as storage memory and stores programs, tables, maps, etc. At least a part of the storage unit 68 may be provided in the processor, integrated circuit, etc. as described above.
[0029] The gas mixing device 20 has two operating modes: a pressure adjustment mode (plasma leak avoidance mode) that adjusts the pressure in the gas flow path 38 to prevent plasma leaks, and a normal operating mode in which the pressure adjustment mode is not performed. The user can switch between the normal operating mode and the pressure adjustment mode by operating the gas mixing device 20. The user can decide whether or not to use the pressure adjustment mode based on the usage period of the artificial lung 18. That is, when a situation arises in which plasma leaks are expected to occur due to the deterioration of the hydrophobicity of the gas exchange membrane 29, the user can decide to switch to the pressure adjustment mode.
[0030] As a pre-configuration for executing the pressure adjustment mode, the user sets the inlet upper pressure limit P1, the outlet upper pressure limit P2, the target pressure Pt of the gas flow path 38, and the valve adjustment range Sv for the gas mixing device 20. Note that these setting parameters may also be set after the user switches to the pressure adjustment mode.
[0031] The inlet-side upper limit pressure P1 is the maximum allowable pressure at the inlet side of the gas flow path 38 in the artificial lung 18. The outlet-side upper limit pressure P2 is the maximum allowable pressure at the outlet side of the gas flow path 38 in the artificial lung 18. The outlet-side upper limit pressure P2 is lower than the inlet-side upper limit pressure P1. The target pressure Pt is the pressure that can prevent plasma leakage in the gas exchange membrane 29. The target pressure Pt can be determined in advance by testing. The valve adjustment range Sv is a parameter that indicates the amount of valve opening adjustment for a single valve opening increase or decrease command. The unit of the valve adjustment range Sv is, for example, the displacement distance (mm) or displacement angle (rad) of the valve body of the pressure control valve 56.
[0032] When the operating mode of the gas exchange system 50 is switched to the pressure adjustment mode, the gas exchange system 50 operates as follows. In the following description, we will mainly refer to Figure 5, and also refer to Figures 1 to 4 as appropriate. Initially, the pressure control valve 56 is in an open state.
[0033] As shown in Figure 5, in step S1, the determination unit 72 determines whether the pressure Ps1 (inlet pressure) detected by the inlet pressure sensor 52 is less than or equal to the inlet upper limit pressure P1. If the determination unit 72 determines that the inlet pressure Ps1 exceeds the inlet upper limit pressure P1 (step S1: NO), the process proceeds to step S2. In step S2, the pressure control valve 56 is opened (pressure purge). This pressure purge causes the pressure in the gas passage 38 to decrease. After step S2 is executed, the process returns to step S1.
[0034] In step S1, if the determination unit 72 determines that the inlet pressure Ps1 is less than or equal to the inlet upper limit pressure P1 (step S1: YES), the process proceeds to step S3. In step S3, the determination unit 72 determines whether the pressure Ps2 (outlet pressure) detected by the outlet pressure sensor 54 is less than or equal to the outlet upper limit pressure P2. If the determination unit 72 determines that the outlet pressure Ps2 exceeds the outlet upper limit pressure P2 (step S3: NO), the process proceeds to step S2. If the determination unit 72 determines that the outlet pressure Ps2 is less than or equal to the outlet upper limit pressure P2 (step S3: YES), the process proceeds to step S4. Step S3 may be omitted.
[0035] Steps S4 to S8 are processing steps for controlling the pressure control valve 56 so that the pressure in the gas passage 38 becomes the target pressure Pt. Specifically, the control unit 74 controls the pressure control valve 56 so that the pressure in the gas passage 38 becomes the target pressure Pt.
[0036] In step S4, the determination unit 72 determines whether the pressure Ps2 detected by the outlet pressure sensor 54 matches the target pressure Pt. If the determination unit 72 determines that the pressure Ps2 detected by the outlet pressure sensor 54 matches the target pressure Pt (step S4: YES), in step S5, the control unit 74 maintains the valve opening of the pressure control valve 56. After step S5, the process returns to step S1.
[0037] If the determination unit 72 determines that the pressure Ps2 detected by the outlet pressure sensor 54 does not match the target pressure Pt (step S4: NO), the process proceeds to step S6. In step S6, the determination unit 72 determines whether the pressure Ps2 is less than the target pressure Pt. If the determination unit 72 determines that the pressure Ps2 is less than the target pressure Pt (step S6: YES), in step S7, the control unit 74 reduces the valve opening of the pressure control valve 56 by the valve adjustment range Sv. This reduces the amount of gas discharged from the gas passage 38 and increases the pressure in the gas passage 38. After step S7, the process returns to step S1.
[0038] If the determination unit 72 determines that the pressure Ps2 is equal to or greater than the target pressure Pt (step S6: NO), in step S8, the control unit 74 increases the valve opening of the pressure control valve 56 by the valve adjustment range Sv. This increases the amount of gas discharged from the gas passage 38 and decreases the pressure in the gas passage 38. After step S8, the process returns to step S1.
[0039] During the execution of the pressure adjustment mode, the above-described processes are repeated. As a result, the pressure in the gas flow path 38 (particularly, the pressure Ps2 which is the outlet-side pressure) is adjusted to the target pressure Pt. As a result, in FIG. 3, since the adjusted pressure acts on the blood toward the micropores 292 of the gas exchange membrane 29, the movement of plasma in the blood through the micropores 292 to the gas phase side (gas flow path 38) is blocked. Thereby, plasma leakage due to deterioration of the gas exchange membrane 29 can be prevented.
[0040] During the execution of the pressure adjustment mode, if the user switches to the normal operation mode, the pressure adjustment mode ends.
[0041] This embodiment has the following effects.
[0042] As shown in FIG. 1, the gas exchange system 50 includes a pressure sensor 54, a pressure control valve 56, and a control unit 74. The control unit 74 controls the pressure control valve 56 so that the pressure in the gas flow path 38 is within a predetermined pressure range. According to such a configuration, in FIG. 3, since the pressure in the gas flow path 38 which is the gas phase side inside the artificial lung 18 is maintained within the predetermined pressure range, plasma leakage due to deterioration of the gas exchange membrane 29 can be prevented. Specifically, by maintaining the internal pressure on the gas phase side inside the artificial lung 18, the inflow of plasma into the gas flow path 38 (the lumen of the hollow fiber membrane 290 which is the gas exchange membrane 29) can be suppressed.
[0043] In FIG. 1, the control unit 74 controls the pressure control valve 56 so that the pressure in the gas flow path 38 becomes the target pressure Pt. According to such a configuration, plasma leakage can be more effectively prevented.
[0044] The pressure sensor 54 is provided in a gas line communicating with the gas flow path 38 of the artificial lung 18. According to such a configuration, the pressure detection in the gas flow path 38 can be realized with a simple configuration.
[0045] The gas line equipped with the pressure sensor 54 is the gas discharge line 42 that discharges gas from the gas passage 38 of the artificial lung 18. With this configuration, since the pressure in the gas passage 38 of the artificial lung 18 is lower at the outlet than at the inlet, the pressure sensor 54 in the gas discharge line 42 allows the pressure in the gas passage 38 to be suitably adjusted to a pressure that can prevent plasma leakage.
[0046] The pressure control valve 56 is provided in the gas discharge line 42. With this configuration, pressure detection and pressure control of the gas flow path 38 can be achieved with a simple setup.
[0047] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the intent of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values or mathematical formulas are used in the description of the embodiments described above.
Claims
1. A gas exchange system comprising: an artificial lung having a blood flow channel for blood, a gas flow channel for oxygen-containing gas, and a gas exchange membrane, and performing gas exchange with the blood via the gas exchange membrane; a pressure control valve provided on a gas discharge line for discharging gas from the gas flow channel of the artificial lung; a pressure sensor for detecting the pressure in the gas flow channel; and a control unit for controlling the pressure control valve so that the pressure in the gas flow channel is within a predetermined pressure range.
2. A gas exchange system according to claim 1, wherein the control unit controls the pressure control valve so that the pressure in the gas flow path becomes the target pressure.
3. A gas exchange system according to claim 1, wherein the pressure sensor is provided in a gas line that communicates with the gas flow path of the artificial lung.
4. A gas exchange system according to claim 3, wherein the gas line on which the pressure sensor is provided is the gas discharge line.
5. A gas exchange system according to claim 4, wherein the pressure control valve is provided in the gas discharge line.