Artificial lung

Abstract

In order to reduce areas where stagnation of blood flowing between a housing (10) and a hollow fiber membrane layer (30) occurs and to improve antithrombotic properties, an artificial lung (100) comprises a housing (10) that has a cylindrical shape, and has a blood inflow port (14) and a blood outflow port (15), and a hollow fiber membrane layer (30) that has a layered structure obtained by winding hollow fiber membranes (31) and is accommodated in the housing (10), wherein blood that has flowed in from the blood inflow port (12) flows from one end portion toward the opposite end portion of the housing (10) in the long axis direction and flows out from the blood outflow port, and the hollow fiber membrane layer (30) has a greater winding interval (P1) of the hollow fiber membranes wound in the outermost layer of the layered structure than a winding interval (P2) of the hollow fiber membranes in the other layers.

Description

artificial lung

[0001] The present invention relates to an oxygenator.

[0002] BACKGROUND ART Extracorporeal circulation systems have been widely used to assist the circulation and breathing of patients during open-heart surgery for heart disease or to temporarily maintain life in the event of rapidly progressing circulatory failure or cardiac arrest.

[0003] The extracorporeal circulation system includes an oxygenator that is incorporated into an extracorporeal circulation circuit consisting of a blood removal line, a blood supply line, etc., and performs gas exchange with the blood, and a pump that is incorporated into the extracorporeal circulation circuit and sends blood to the oxygenator.

[0004] In an extracorporeal circulation system, an oxygenator performs gas exchange (adding oxygen to the blood and removing carbon dioxide) on the removed blood using a hollow fiber membrane layer disposed within the oxygenator, and then sends the blood to a blood supply line (see, for example, Patent Document 1).

[0005] DE 103 41 221 A1

[0006] When an extracorporeal circulation system is used for a long period of time, the formation of blood clots in the oxygenator becomes a problem. The oxygenator contains a hollow fiber membrane layer in a cylindrical housing, and blood flow can stagnate due to irregular winding of the hollow fiber membranes in the hollow fiber membrane layer, leading to the formation of blood clots between the hollow fiber membrane layer and the housing.

[0007] The present invention has been made in consideration of the above problems, and aims to provide an artificial lung that suppresses stagnation of blood flowing between a housing and a hollow fiber membrane layer and improves antithrombotic properties.

[0008] The above object of the present invention can be achieved by the following means (1) to (5).

[0009] (1) An artificial lung comprising: a cylindrical housing having a blood inlet port and a blood outlet port; and a hollow fiber membrane layer having a laminated structure in which hollow fiber membranes are wound and contained within the housing, wherein blood flowing in through the blood inlet port flows from one end of the housing to the other end in the longitudinal direction and flows out through the blood outlet port, and wherein the hollow fiber membrane layer has a winding interval of the hollow fiber membrane wound in the outermost layer in the laminated structure that is wider than the winding intervals of the hollow fiber membranes in other layers.

[0010] (2) The oxygenator according to (1) above, wherein the hollow fiber membrane layers are wound more loosely in only the outermost layer of the laminated structure than in the other layers.

[0011] (3) The oxygenator according to (1) or (2) above, wherein the number of windings in the outermost layer of the hollow fiber membrane layer in the laminated structure is less than the number of windings in the other layers.

[0012] (4) The artificial lung according to any one of (1) to (3) above, wherein the hollow fiber membrane layers have a discontinuous winding interval in the laminated structure, and the difference in the winding interval between the hollow fiber membrane in the outermost layer and the hollow fiber membrane in any other layer is larger than the difference in the winding interval between any other layers.

[0013] (5) The oxygenator according to any one of (1) to (4) above, wherein the hollow fiber membrane layer has a winding interval of 1.5 mm or more for the outermost layer in the laminated structure.

[0014] In the oxygenator according to the present embodiment, blood flows from the blood inlet port to the blood outlet port from one longitudinal end of the housing to the other longitudinal end. To ensure that blood flows through the outermost layer of the hollow fiber membrane layer from one longitudinal end of the housing to the other longitudinal end, the spacing between the hollow fiber membranes wound around the outermost layer of the hollow fiber membrane layer is wider than that of the other layers. This creates a blood-passageway in the outermost layer that is equal to the spacing between the hollow fiber membranes. This directs blood flow between the inner circumferential surface of the housing and the hollow fiber membrane layer from one longitudinal end to the other longitudinal end of the housing, thereby increasing the flow velocity of blood through the outermost layer of the hollow fiber membrane layer. Therefore, by increasing the flow velocity of blood through the outermost layer of the hollow fiber membrane layer, the oxygenator can suppress the formation of blood stagnation areas in the outermost layer of the hollow fiber membrane layer and enhance its antithrombotic properties.

[0015] Fig. 1 is a longitudinal sectional view of an oxygenator of a first embodiment according to the present embodiment; Fig. 2 is a transverse sectional view of an oxygenator of a first embodiment according to the present embodiment; Fig. 3 is a partial transverse sectional view of a hollow fiber membrane layer of an oxygenator of a first embodiment according to the present embodiment; Fig. 4 is a view of the periphery of the outermost layer of a hollow fiber membrane layer of an oxygenator of a first embodiment according to the present embodiment; Fig. 5 is a longitudinal sectional view of an oxygenator of a second embodiment according to the present embodiment;

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments shown here are merely examples for embodying the technical idea of ​​the present invention and are not intended to limit the present invention. Furthermore, all other embodiments, examples, and operational techniques that can be conceived by those skilled in the art without departing from the spirit of the present invention are included in the scope and spirit of the present invention, as well as in the scope of the inventions set forth in the claims and their equivalents.

[0017] Furthermore, for the convenience of illustration and ease of understanding, the drawings attached to this specification may be represented schematically with the scale, aspect ratio, shape, etc. appropriately changed from the actual product, but these are merely examples and do not limit the interpretation of the present invention.

[0018] For ease of explanation, the following directions are defined in this specification. In Figure 1, the "longitudinal direction" is the direction along the central axis C of the oxygenator 100 in the longitudinal direction. The "radial direction" is the direction moving away from or approaching the central axis C of the oxygenator 100 in an orthogonal cross section (transverse cross section) with the central axis C of the oxygenator 100 as the reference axis. The "circumferential direction" is the direction of rotation with the central axis C of the oxygenator 100 as the reference axis. The central axis C substantially coincides with the central axes of the outer tube 11 and inner tube 12 that make up the housing 10.

[0019] The present inventors embarked on the development of a new oxygenator to solve the problem of thrombus formation due to blood stagnation, which was an issue with conventional devices. They then fundamentally redesigned the blood flow path and blood flow direction in the oxygenator, and discovered that partial blood stagnation could be suppressed by circulating blood flowing from one end of the blood inlet port to the other end of the housing in the longitudinal direction and then outflowing it from the blood outlet port.

[0020] The artificial lung with the new blood flow path eliminates blood flow stagnation in the outermost layer of the hollow fiber membrane layer, providing antithrombotic properties. However, a new problem has been discovered: blood may stagnate in areas such as where the housing and hollow fiber membrane layer come into contact.

[0021] The present inventors have conducted further research into this new problem and have discovered that the above problem can be solved by adopting a structure that allows blood flowing between the housing and the outermost or innermost layer of the hollow fiber membrane layer to flow from one end of the housing to the other end in the longitudinal direction of the housing, thereby increasing the flow rate of blood in the outermost layer of the hollow fiber membrane layer.The present invention is a novel oxygenator developed based on this finding.

[0022] In the following description, when ordinal numbers such as "first" and "second" are used, unless otherwise specified, they are used for convenience and do not stipulate any particular order.

[0023] [Device Configuration] The oxygenator 100 according to the present invention will be described.

[0024] The oxygenator 100 is incorporated into an extracorporeal circulation circuit and performs gas exchange with blood. The oxygenator 100 is a membrane oxygenator that performs gas exchange with blood via hollow fiber membranes 31.

[0025] 1, the oxygenator 100 comprises a cylindrical housing 10, a core 20 housed in the storage space 11a of the housing 10, a hollow fiber membrane layer 30 formed by a bundle of hollow fiber membranes 31 wound and stacked around the core 20, a blood chamber 40 formed between the housing 10 and the hollow fiber membrane layer 30, and a blood flow path 50 that serves as a blood flow path within the housing 10. Note that there are portions where the outer peripheral surface of the core 20 and the inner peripheral surface of the hollow fiber membrane layer 30 are in partial contact. In other words, the blood chamber 40 is formed by a gap in the portion where the outer peripheral surface of the core 20 and the inner peripheral surface of the hollow fiber membrane layer 30 do not contact each other.

[0026] <Housing> The housing 10 is a housing that constitutes the main body of the oxygenator 100. As shown in Fig. 1 , the housing 10 has a cylindrical outer cylinder 11 that extends in the longitudinal direction (the vertical direction in Fig. 1 ), an inner cylinder 12 that is housed in the outer cylinder 11, a lid 13 that is airtightly connected to the outer peripheral ends of the outer cylinder 11 and the inner cylinder 12, a blood inlet port 14 that allows blood to flow into the housing 10, and a blood outlet port 15 that allows blood circulating within the housing 10 to flow out to the outside.

[0027] 1, the outer cylinder 11 has a cylindrical shape and has an internal storage space 11a for storing the core 20 and the hollow fiber membrane layer 30. A blood outlet port 15 is provided at the base end of the outer cylinder 11 so as to extend in a direction intersecting the longitudinal direction of the outer cylinder 11.

[0028] 1, the inner cylinder 12 has a cylindrical shape with a smaller diameter than the outer cylinder 11. The inner cylinder 12 functions as the annular inner peripheral portion of the housing 10. A plurality of protrusions 12a are arranged at predetermined intervals in the circumferential direction on the distal end side of the inner cylinder 12 to position the blood inflow port 14 and to provide gaps that serve as guide portions 14a.

[0029] The lid portion 13 is a bottomed, annular member having a concave cross-section, and airtightly closes the tip end of the outer tube 11 in the longitudinal direction when the inner tube 12, blood inlet port 14, core 20, and hollow fiber membrane layer 30 are housed in the outer tube 11.

[0030] A gas inlet port 10A is provided in the outer bottom 11b of the oxygenator 100, allowing gas for gas exchange with blood to flow into the housing 10. A gas outlet port 10B is provided in the lid 13, allowing gas to flow out after gas exchange. To improve the efficiency of gas exchange in the blood, the gas inlet port 10A is preferably positioned opposite the direction of blood flow through the storage space 11a (blood chamber 40) so that gas can flow into the blood chamber 40 (i.e., toward the base end of the outer cylinder 11, downstream in the direction of blood flow). The gas outlet port 10B is preferably positioned approximately opposite the gas inlet port 10A in the longitudinal direction (i.e., toward the tip end of the outer cylinder 11, upstream in the direction of blood flow). The positions of the gas inlet port 10A and the gas outlet port 10B are not limited to those shown in FIG. 1 and may be any positions that allow gas exchange with blood within the storage space.

[0031] The blood inflow port 14 is configured to be detachable from the housing 10 and is disposed on the distal end side of the inner cylinder 12 of the housing 10. The blood inflow port 14 is connected to a blood removal path in the extracorporeal circulation circuit of the extracorporeal circulation system, and allows blood to flow into the housing 10. A distal opening serving as an inlet of the blood inflow port 14 is formed facing the distal end side in the longitudinal direction of the housing 10. The blood flowing in from the blood inflow port 14 flows into the blood chamber 40 through a guide portion 14a formed between the port and the distal end side of the inner cylinder 12.

[0032] The blood outlet port 15 extends in a direction intersecting the flow direction of blood flowing through the housing 10 (the longitudinal direction of the housing 10) and is disposed on the outer periphery of the outer cylinder 11. The blood outlet port 15 is connected to a blood feed path in the extracorporeal circulation circuit of the extracorporeal circulation system, and causes blood that has flowed through the housing 10 to flow into the blood feed path. In the embodiment shown in Fig. 1, the distal opening of the blood outlet port 15 is formed facing the distal end of the housing 10, similar to the distal opening that serves as the outlet of the blood outlet port 15. However, the orientation of the distal opening of the blood outlet port 15 is not limited to this.

[0033] The housing 10 is preferably transparent to the extent that the blood flow inside can be visually observed. In this specification, "transparent" includes colorless transparent, colored transparent, and translucent.

[0034] The material constituting the housing 10 is not particularly limited, but examples thereof include polyolefins such as polyethylene and polypropylene, ester-based resins such as polyethylene terephthalate, polystyrene, styrene-based resins such as MS resin and MBS resin, and polycarbonate.

[0035] <Core> The core 20 has a cylindrical shape, and is housed in the housing 10 with the hollow fiber membrane 31 wound therearound to form the hollow fiber membrane layer 30. The core 20 is attached so as to cover the inner cylinder 12.

[0036] The material constituting the core 20 is not particularly limited, but examples thereof include polyolefins such as polyethylene and polypropylene, ester-based resins such as polyethylene terephthalate, polystyrene, styrene-based resins such as MS resin and MBS resin, and polycarbonate.

[0037] <Hollow Fiber Membrane Layer> As shown in FIG. 1, the hollow fiber membrane layer 30 is formed by winding hollow fiber membranes 31 around the core 20 and laminating them in multiple layers.

[0038] As shown in FIG. 1, the hollow fiber membrane layer 30 has a gas exchange section 32 .

[0039] The gas-exchanging section 32 is formed by a bundle of hollow fiber membranes 31. In the gas-exchanging section 32, oxygen circulating through the gas-exchanging section 32 diffuses into the blood side as it passes through the hollow fiber membranes 31. Carbon dioxide in the blood circulating through the gas-exchanging section 32 is discharged into the lumen of the hollow fiber membranes 31. As a result, in the gas-exchanging section 32, gas exchange of oxygen and carbon dioxide takes place between the gas-exchanging section 32 and the blood via the hollow fiber membranes 31.

[0040] The oxygen flowing in through the gas inlet port 10A undergoes gas exchange with carbon dioxide in the blood in the gas exchange section 32, and the carbon dioxide that has undergone gas exchange is discharged to the outside of the oxygenator 100 through the gas outlet port 10B.

[0041] As shown in FIG. 3 , the hollow fiber membrane layer 30 has a winding interval (P1) between the hollow fiber membranes 31 wound around the core 20 (corresponding to the separation distance between adjacent hollow fiber membranes 31 in the circumferential direction) that is different between the winding interval P1 of the outermost layer and the winding interval P2 of the other layers in the laminated structure. Specifically, the winding interval P1 of the hollow fiber membrane 31 in the outermost layer in the laminated structure of the hollow fiber membrane layer 30 is wider than the winding interval P2 of the hollow fiber membranes 31 in the other layers. In other words, the hollow fiber membrane layer 30 has hollow fiber membranes 31 wound more sparsely in the outermost layer than in the other layers in the laminated structure. Furthermore, the winding interval P1 of the hollow fiber membrane 31 in the laminated structure of the hollow fiber membrane layer 30 is discontinuous, and the difference in the interval P1 between the winding interval P2 of the hollow fiber membranes 31 in the outermost layer and the winding interval P2 of the hollow fiber membranes 31 in the other layers can be said to be greater than the difference in the interval P2 between any other layers.

[0042] In the hollow fiber membrane layer 30, the winding interval P1 of the outermost layer is wider than the winding interval P2 of the other layers, so that the number of windings of the hollow fiber membrane 31 in the outermost layer in the laminated structure can be made smaller than the number of windings of the hollow fiber membrane 31 in the other layers.

[0043] As shown in Figure 4, the hollow fiber membrane layer 30 has a flow passage 16 in the outermost layer through which blood can flow, the flow passage 16 having a width equal to the winding interval P1, by making the winding interval P1 wider than the winding interval P2 between the hollow fiber membranes 31 in the other layers. This flow passage 16 extends from the distal end to the proximal end of the housing 10. As a result, the flow direction of blood flowing between the inner circumferential surface of the housing 10 and the hollow fiber membrane layer 30 is defined as passing through this flow passage 16 from the distal end to the proximal end of the housing 10. Therefore, the oxygenator 100 can form a flow of blood flowing through the outermost layer of the hollow fiber membrane layer 30 in the blood chamber 40 of the housing 10 from the distal end to the proximal end of the housing 10 through the flow passage 16. As a result, the oxygenator 100 increases the flow rate of blood flowing through the outermost layer of the hollow fiber membrane layer 30, further uniforming the blood flow, suppressing the formation of stagnation areas within the blood chamber 40, and improving antithrombotic properties.

[0044] When the winding spacing P1 of the hollow fiber membrane 31 of the outermost layer of the hollow fiber membrane layer 30 is 1.5 mm or more, the formation of blood stagnation areas is suppressed while the blood flow direction is easily formed from the tip end side to the base end side of the housing 10.

[0045] The hollow fiber membrane layer 30 is advantageously positioned in contact with the inner peripheral surface of the housing 10 (the inner peripheral surface of the outer tube 11) because it can function more effectively as the flow passage 16 formed in the outermost hollow fiber membrane 31.

[0046] The hollow fiber membrane layer 30 has a laminated structure in which hollow fiber membranes 31 are wound around the core 20 in multiple layers, and can be formed, for example, by winding one or a bundle of hollow fiber membranes 31 around the core 20 in a spiral shape at an angle with respect to the central axis C of the core 20 and approximately parallel to the axis of the core 20. The hollow fiber membrane 31 is formed by forming a large number of hollow fibers having a gas exchange function into a cylindrical shape.

[0047] The material of the hollow fiber membrane 31 is not particularly limited as long as it allows gas exchange with the blood, but for example, hydrophobic polymer materials such as polypropylene, polyethylene, polysulfone, polyacrylonitrile, polytetrafluoroethylene, and polymethylpentene can be used.

[0048] Next, the flow of blood in the oxygenator 100 will be described.

[0049] In the oxygenator 100 , blood flows through a blood flow path 50 that passes from the blood inlet port 14 through the guide portion 14 a and the blood chamber 40 in this order to reach the blood outlet port 15 .

[0050] First, blood flowing in from the blood inlet port 14 flows through the guide portion 14 a and is guided to the blood chamber 40 .

[0051] The blood introduced into the blood chamber 40 expands as it flows from the distal end to the proximal end of the housing 10, circulating between the inner circumferential surface of the outer cylinder 11 and the outermost layer of the hollow fiber membrane layer 30 and through the interior of the hollow fiber membrane layer 30. As the blood passes through the hollow fiber membrane layer 30, it moves through the gaps in the hollow fiber membranes 31 and undergoes gas exchange with oxygen in the gas exchange section 32.

[0052] Blood flowing between the inner peripheral surface of the outer cylinder 11 and the surface of the outermost layer of the hollow fiber membrane layer 30 passes through a flow passage 16 formed by the hollow fiber membrane 31 wound around the outermost layer of the hollow fiber membrane layer 30, and flows through the outermost layer of the hollow fiber membrane layer 30 along the longitudinal direction of the housing 10 from the distal end to the proximal end of the housing 10. This prevents blood from stagnating in the outermost layer of the hollow fiber membrane layer 30, making it less likely for thrombus to form.

[0053] The blood that has undergone gas exchange flows out of the oxygenator 100 from the blood outlet port 15 that communicates with the blood chamber 40, and returns to the human body via the extracorporeal circulation circuit.

[0054] Next, a method for manufacturing the oxygenator 100 will be described.

[0055] First, the core 20 is set on a connecting member connected to the motor of the manufacturing device, and the hollow fiber membrane 31 is wound spirally around the outer periphery of the core 20 while the core 20 is rotated.

[0056] In this case, the hollow fiber membrane layer 30 is wound densely from the outermost layer onward, and when forming the outermost layer, the winding interval P1 of the hollow fiber membrane 31 is set wider than the winding interval P2 of the other layers. As a result, in the outermost layer of the hollow fiber membrane layer 30, flow paths 16 are formed by the gaps between the hollow fiber membranes 31.

[0057] The number of hollow fiber membranes 31 extruded by the manufacturing apparatus is not particularly limited and may be one or more (approximately two to six), but using one allows for easy adjustment of the winding interval of the hollow fiber membrane 31 during winding. Furthermore, when winding the hollow fiber membrane 31, if multiple membranes are wound until the outermost layer is reached and then only one membrane is wound when the outermost layer is formed, the manufacturing time for the hollow fiber membrane layer 30 can be shortened and production efficiency improved. Furthermore, controlling the winding interval of the outermost layer of the hollow fiber membrane 31 (for example, to a winding interval of 1.5 mm or more) can be achieved by appropriately adjusting the number of rotations of the winding by the control device and controlling the control device to drive the control device.

[0058] After the winding of the hollow fiber membrane 31 is completed, the outer cylinder 11 is attached, and both ends of the hollow fiber membrane layer 30 are fixed with urethane, and then the both ends are cut. This process exposes the ends of the hollow fiber membrane layer 30, allowing oxygen to enter.

[0059] Then, the distal and proximal ends of the outer cylinder 11, the lid portion 13, etc. are attached, and the oxygenator 100 is obtained.

[0060] [Second Embodiment] Next, an oxygenator according to a second embodiment of the present invention will be described. In the following description of the embodiment, differences from the above-described embodiment will be mainly described. Components having the same functions as those of the first embodiment will be denoted by the same or related reference numerals, and detailed description will be omitted without any particular mention. Furthermore, the configuration, members, and method of use may be the same as those of the first embodiment.

[0061] The oxygenator 100A of the second embodiment has two hollow fiber membrane layers 30, one of which performs gas exchange and the other performs heat exchange. Therefore, the hollow fiber membrane layers 30 of the oxygenator 100A have a gas exchange section 32 and a heat exchange section 33.

[0062] 5, the oxygenator 100A includes a housing 10, a core 20, a hollow fiber membrane layer 30, a first blood chamber 41, a second blood chamber 42, and a blood flow path 50. The blood inlet port 14 communicates with the second blood chamber 42 via a guide portion 14a. The blood outlet port 15 communicates with the first blood chamber 41 and is formed at the tip of the outer cylinder 11 downstream of the blood flow path 50 in the direction of blood flow.

[0063] The outer tube 11 of the housing 10 has a partition wall 11d that separates the gas exchange hollow fiber membrane layer 30A (first hollow fiber membrane layer 30A) from the heat exchange hollow fiber membrane layer 30 (second hollow fiber membrane layer 30B) within the storage space 11a that houses the hollow fiber membrane layer 30A.

[0064] The partition wall 11d is formed around the entire circumferential direction of the outer cylinder 11 and separates the accommodation space 11a into two spaces. Similar to the inner cylinder 12, the partition wall 11d functions as an annular inner peripheral portion of the housing 10.

[0065] A communication hole 17 is formed on the downstream side of the partition 11 d in the blood flow direction, which communicates between the two spaces separated by the partition 11 d. The communication hole 17 allows blood flowing through the second blood chamber 42 to flow to the first blood chamber 41.

[0066] In addition to the gas inlet port 10A and the gas outlet port 10B, the housing 10 of the oxygenator 100A also has a heat medium inlet port 10C through which a heat medium flows into the heat exchanger 33 and a heat medium outlet port 10D through which the heat-exchanged heat medium flows out of the heat exchanger 33. As a result, in the oxygenator 100A, blood flowing in through the blood inlet port 14 undergoes gas exchange as it passes through the hollow fiber membranes 31A of the first hollow fiber membrane layer 30A while flowing through the gas exchanger 32, and undergoes heat exchange as it passes through the hollow fiber membranes 31B of the second hollow fiber membrane layer 30B while flowing through the heat exchanger 33. The second hollow fiber membrane layer 30B housed in the heat exchanger 33 may be disposed so as to cover the entire second blood chamber 42 corresponding to the heat exchanger 33, as shown in FIG. 5, or may be disposed so as to form a partial space. That is, the second hollow fiber membrane layer 30B can be appropriately modified depending on the specifications of the heat exchanger 33.

[0067] From the viewpoint of improving the efficiency of gas exchange in the blood, the gas inlet port 10A is preferably disposed in a position (near the distal end of the outer cylinder 11, which is downstream in the direction of blood flow) opposite the direction of blood flow through the housing 10 so that gas can flow into the first blood chamber 41. The gas outlet port 10B is preferably disposed in a position (near the proximal end of the outer cylinder 11, which is upstream in the direction of blood flow) substantially opposite the gas inlet port 10A in the longitudinal direction. The positions of the gas inlet port 10A and the gas outlet port 10B are not limited to those shown in FIG. 5 , and may be any positions that allow heat exchange of the blood within the first blood chamber 41.

[0068] From the viewpoint of improving the heat exchange efficiency of the blood, the heat medium inlet port 10C is preferably disposed in a position facing the flow direction of blood flowing through the housing 10 so that the heat medium can flow into the second blood chamber 42 (i.e., toward the base end of the outer cylinder 11, which is downstream in the direction of blood flow). The heat medium outlet port 10D is preferably disposed in a position substantially opposite the heat medium inlet port 10C in the longitudinal direction (i.e., toward the tip end of the outer cylinder 11, which is upstream in the direction of blood flow). The positions of the heat medium inlet port 10C and the heat medium outlet port 10D are not limited to those shown in FIG. 5 , and may be any positions that allow heat exchange of the blood in the second blood chamber 42.

[0069] The oxygenator 100A has a flow passage 16 formed by the winding interval P1 of the hollow fiber membrane 31 between the outermost hollow fiber membrane 31A of the first hollow fiber membrane layer 30A housed in the first blood chamber 41 and the inner circumferential surface of the outer cylinder 11. The oxygenator 100A also has a flow passage 16 formed by the winding interval P1 of the hollow fiber membrane 31 between the outermost hollow fiber membrane 31B of the second hollow fiber membrane layer 30B housed in the second blood chamber 42 and the inner circumferential surface of the partition wall 11d.

[0070] Next, the flow of blood in the oxygenator 100A will be described.

[0071] In the oxygenator 100A, blood flows through a blood flow path 50 from the blood inlet port 14 through the guide portion 14a, the second blood chamber 42, and the first blood chamber 41 in this order to reach the blood outlet port 15.

[0072] First, blood flowing in from the blood inlet port 14 is guided to the second blood chamber 42 through the guide portion 14a.

[0073] The blood introduced into the second blood chamber 42 expands as it flows between the outer peripheral surface of the inner tube 12 and the innermost layer of the second hollow fiber membrane layer 30B and through the interior of the second hollow fiber membrane layer 30B, from the distal end toward the proximal end of the housing 10. As the blood passes through the second hollow fiber membrane layer 30B, it undergoes heat exchange in the heat exchanger 33 while moving through the gaps in the hollow fiber membranes 31B.

[0074] In the oxygenator 100A, blood flowing between the inner circumferential surface of the partition wall 11d and the surface of the outermost layer of the second hollow fiber membrane layer 30B in the second blood chamber 42 passes through the flow passage 16 formed by the hollow fiber membrane 31B and flows through the outermost layer of the second hollow fiber membrane layer 30B from the distal end toward the proximal end of the housing 10 along the longitudinal direction of the housing 10. Therefore, in the oxygenator 100A, the formation of blood stagnation areas in the outermost layer of the second hollow fiber membrane layer 30B is suppressed, making it less likely for thrombi to form.

[0075] The blood that has passed through the second blood chamber 42 flows into the first blood chamber 41 through the communication hole 17 .

[0076] The blood that has flowed into the first blood chamber 41 expands as it flows between the inner circumferential surface of the outer cylinder 11 and the outermost layer of the first hollow fiber membrane layer 30A and through the inside of the first hollow fiber membrane layer 30A, from the base end side to the tip end side of the housing 10. As the blood passes through the first hollow fiber membrane layer 30A, it moves through the gaps in the hollow fiber membranes 31A and undergoes gas exchange with oxygen in the gas exchange section 32.

[0077] In the oxygenator 100A, blood flowing between the inner peripheral surface of the outer cylinder 11 and the surface of the outermost layer of the first hollow fiber membrane layer 30A in the first blood chamber 41 passes through the flow passage 16 formed by the hollow fiber membrane 31A and flows through the outermost layer of the first hollow fiber membrane layer 30A from the proximal end of the housing 10 toward the distal end thereof along the longitudinal direction of the housing 10. Therefore, in the oxygenator 100A, as in the first embodiment, the formation of blood stagnation areas in the outermost layer of the hollow fiber membrane layer 30 is suppressed, making it difficult for thrombi to form.

[0078] In this way, in the artificial lung 100A, blood flowing in from the blood inlet port 14 flows through the second blood chamber 42 in the longitudinal direction from the tip end side to the base end side of the housing 10, flows into the first blood chamber 41 through the communicating hole 17, and then flows in the longitudinal direction from the base end side to the tip end side of the housing 10 and flows out from the blood outlet port 15.

[0079] The blood that has undergone gas exchange flows out of the oxygenator 100A from the blood outlet port 15 that communicates with the first blood chamber 41, and returns to the human body via the extracorporeal circulation circuit.

[0080] [Effects] As described above, the artificial lung 100 according to this embodiment comprises a cylindrical housing 10 having a blood inlet port 14 and a blood outlet port 15, and a hollow fiber membrane layer 30 having a laminated structure in which hollow fiber membranes 31 are wound and contained within the housing 10, in which blood flowing in through the blood inlet port 14 flows from one end to the other end in the longitudinal direction of the housing 10 and flows out through the blood outlet port 15, and in the hollow fiber membrane layer 30, the winding interval P1 of the hollow fiber membrane wound in the outermost layer in the laminated structure is wider than the winding interval P2 of the hollow fiber membranes in the other layers.

[0081] Furthermore, the hollow fiber membrane layer 30 of the oxygenator 100 may be configured so that the hollow fiber membranes 31 are wound more loosely in only the outermost layer of the laminated structure than in the other layers.

[0082] Furthermore, the hollow fiber membrane layer 30 of the oxygenator 100 may have a laminated structure in which the number of windings of the hollow fiber membrane 31 in the outermost layer is less than the number of windings of the hollow fiber membrane 31 in the other layers.

[0083] In addition, the hollow fiber membrane layer 30 of the oxygenator 100 has a laminated structure in which the winding intervals of the hollow fiber membranes 31 are discontinuous, and the difference in spacing between the winding interval P1 of the hollow fiber membrane 31 in the outermost layer and the winding interval P2 of the hollow fiber membranes in the other layers may be larger than the difference in spacing between the winding intervals P2 between any other layers.

[0084] With this configuration, in the oxygenator 100, the winding interval P1 of the hollow fiber membrane 31 in the outermost layer is wider than the winding interval P2 of the hollow fiber membranes 31 in the other layers, and a flow passage 16 through which blood can flow is formed in the outermost layer, extending from the distal end to the proximal end of the housing 10 and having the same width as the winding interval P1. As a result, in the oxygenator 100, blood flowing through the outermost layer of the hollow fiber membrane layer 30 in the blood chamber 40 of the housing 10 can flow through the flow passage 16 and along the longitudinal direction of the housing 10. Therefore, in the oxygenator 100, the flow rate of blood flowing through the outermost layer of the hollow fiber membrane layer 30 is increased and the blood flow can be made uniform, which results in suppressing the formation of stagnation areas in the blood chamber 40 and improving antithrombotic properties.

[0085] Furthermore, the hollow fiber membrane layer 30 of the oxygenator 100 may have a layered structure in which the winding interval of the outermost layer is 1.5 mm or more.

[0086] With this configuration, the oxygenator 100 has a blood passage 16 extending from the distal end to the proximal end of the housing 10 in the outermost layer, which is formed with a flow path width that allows smooth blood flow while suppressing the formation of blood stagnation areas. Therefore, the oxygenator 100 increases the flow rate of blood flowing between the housing 10 and the outermost layer of the hollow fiber membrane layer 30, suppressing the formation of stagnation areas in the blood chamber 40 and improving antithrombotic properties.

[0087] This application is based on Japanese Patent Application No. 2023-164700, filed on September 27, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0088] 10 Housing, 10A Gas inlet port, 10B Gas outlet port, 10C Heat medium inlet port, 10D Heat medium outlet port, 11 Outer tube (11a Storage space, 11b Outer bottom, 11c Inner bottom, 11d Partition), 12 Inner tube (12a Protrusion), 13 Lid, 14 Blood inlet port, 15 Blood outlet port, 16 Flow path, 17 Communication hole, 20 Core, 30 Hollow fiber membrane layer, 30A First hollow fiber membrane layer, 30B Second hollow fiber membrane layer, 31, 31A, 31B Hollow fiber membrane, 32 Gas exchange section, 33 Heat exchange section, 40 Blood chamber, 41 First blood chamber, 42 Second blood chamber, 50 Blood flow path, 100, 100A Oxygenator; C: central axis; P1: winding interval between hollow fiber membranes in the outermost layer of the hollow fiber membrane layer; P2: winding interval between hollow fiber membranes in other layers of the hollow fiber membrane layer.

Claims

1. An artificial lung comprising: a cylindrical housing having a blood inlet port and a blood outlet port; and a hollow fiber membrane layer having a laminated structure of wound hollow fiber membranes and contained within the housing, wherein blood flowing in from the blood inlet port flows from one end to the other end in the longitudinal direction of the housing and flows out from the blood outlet port, and wherein the winding spacing of the hollow fiber membrane wound in the outermost layer of the laminated structure of the hollow fiber membrane layer is wider than the winding spacing of the hollow fiber membrane in other layers.

2. The artificial lung as described in claim 1, wherein the hollow fiber membrane layers are wound more loosely in the outermost layer of the laminated structure than in the other layers.

3. The artificial lung according to claim 1, wherein the number of turns of the hollow fiber membrane in the outermost layer in the laminate structure is less than the number of turns of the hollow fiber membrane in the other layers.

4. The artificial lung described in claim 1, wherein the hollow fiber membrane layers have a discontinuous winding interval in the laminated structure, and the difference in the winding interval between the hollow fiber membrane in the outermost layer and the hollow fiber membrane in any other layer is greater than the difference in the winding interval between any other layers.

5. An artificial lung as described in any one of claims 1 to 4, wherein the hollow fiber membrane layer has a winding spacing of 1.5 mm or more for the outermost layer in the laminate structure.

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