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) formed by winding hollow fiber membranes and accommodated in the housing (10), wherein blood that has flowed in from the blood inflow port (14) 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 (15), and the housing (10) has a plurality of protruding portions (16) that protrude inward in the radial direction from the inner circumferential surface of the housing (10) and extend from a distal end portion toward a base end portion of the housing (10).

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 (6).

[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 formed by winding a hollow fiber membrane 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 the housing has a plurality of raised portions that protrude radially inward from the inner surface of the housing toward the surface of the outermost layer of the hollow fiber membrane layer and extend from the tip end of the housing toward the base end.

[0010] (2) The oxygenator described in (1) above, wherein the raised portions are formed so that their tops abut against the outer peripheral surface of the hollow fiber membrane layer, and a blood flow passage is formed between adjacent raised portions in the circumferential direction of the housing.

[0011] (3) The oxygenator according to (1) or (2) above, wherein the flow passage functions as a retention suppression section that suppresses the formation of a blood retention area within the housing.

[0012] (4) An artificial lung described in any one of (1) to (3) above, wherein the raised portion has a mountain-like shape with a smooth outer surface that reduces in amount of protrusion from the center outward when viewed in a cross section perpendicular to the longitudinal direction.

[0013] (5) An artificial lung according to any one of (1) to (4) above, wherein the raised portions are smoothly connected to adjacent raised portions in the circumferential direction.

[0014] (6) An oxygenator according to any one of (1) to (5) above, wherein the raised portion is formed continuously or discontinuously from the tip end to the base end of the housing.

[0015] According to the oxygenator of this embodiment, in a device configuration in which blood flows from one end of the housing to the other end in the longitudinal direction of the housing, from the blood inlet port to the blood outlet port, the oxygenator includes a raised portion that directs the flow direction of blood through the outermost layer of the hollow fiber membrane layer from one end to the other end in the longitudinal direction of the housing. The raised portion regulates the flow of blood through the outermost layer of the hollow fiber membrane layer within the housing from one end to the other end in the longitudinal direction of the housing, thereby increasing the flow rate. Therefore, by increasing the flow rate of blood through the outermost layer of the hollow fiber membrane layer using the raised portion, the oxygenator can suppress the formation of blood stagnation areas in the outermost layer of the hollow fiber membrane layer and improve antithrombotic properties.

[0016] FIG. 1 is a longitudinal sectional view of an oxygenator according to a first embodiment of the present invention; FIG. 2 is a schematic horizontal sectional view of an oxygenator according to the present invention; FIG. 3 is a partially enlarged view of the periphery of a raised portion of an oxygenator according to the present invention; FIG. 4 is a view showing the form of an outer raised portion of an oxygenator according to the present invention; FIG. 5 is a view showing a first modified example of an outer raised portion of an oxygenator according to the present invention; FIG. 6 is a view showing a second modified example of an outer raised portion of an oxygenator according to the present invention; FIG. 7 is a view showing the form of an inner raised portion of an oxygenator according to the present invention; FIG. 8 is a view showing a first modified example of an inner raised portion of an oxygenator according to the present invention; FIG. 9 is a view showing the periphery of a recessed portion of an oxygenator according to the present invention; FIG. 10 is a longitudinal sectional view of an oxygenator according to a second embodiment of the present invention;

[0017] 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.

[0018] 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.

[0019] 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. The "radial direction" is the direction moving away from or approaching the central axis C 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.

[0020] 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.

[0021] 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 flowing out of the blood outlet port.

[0022] The artificial lung with the new blood flow path eliminates blood stagnation in the outermost layer and provides antithrombogenicity. 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.

[0023] The present inventors conducted further research into this new problem and discovered that adopting a structure that allows blood flowing through the outermost and innermost portions 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 increases the flow rate of blood in the outermost portion of the hollow fiber membrane layer, thereby solving the problem. The present invention is a novel oxygenator developed based on this finding. The outermost and innermost portions of the hollow fiber membrane layer include not only the outermost and innermost surfaces of the hollow fiber membrane layer itself, but also the innermost surface of the core, which serves as the winding axis when the hollow fiber membrane layer is formed. Therefore, blood flowing through the outermost and innermost portions of the hollow fiber membrane layer refers to blood flowing between the hollow fiber membrane layer (or core) and the components of the housing.

[0024] First Embodiment An oxygenator 100 according to a first embodiment of the present invention will be described.

[0025] 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.

[0026] 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.

[0027] <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 extending in the longitudinal direction (the up-down direction in Fig. 1 ), an inner cylinder 12 housed in the outer cylinder 11, a lid 13 airtightly connected to the outer peripheral ends of the outer cylinder 11 and the inner cylinder 12, a blood inlet port 14 for introducing blood into the housing 10, a blood outlet port 15 for discharging blood circulating within the housing 10 to the outside, raised portions 16 that bulge radially inward or outward on the inner peripheral surface of the outer cylinder 11 or the outer peripheral surface of the inner cylinder 12, and a recess 17 located at the downstream end of the raised portion 16 formed on the inner cylinder 12 in the blood flow direction.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] The blood outlet port 15 extends in a direction intersecting the flow direction of blood 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 can be provided at the proximal end of the housing 10. 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 out 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 inlet of the blood inlet port 14. However, the orientation of the distal opening of the blood outlet port 15 is not limited to this.

[0034] The raised portion 16 is formed to extend from one end to the other end in the longitudinal direction of the housing 10. As shown in Fig. 2, the raised portion 16 has an outer raised portion 16a that protrudes radially inward from the inner peripheral surface of the outer tube 11 toward the surface of the outermost layer of the hollow fiber membrane layer 30 and extends from the distal end to the proximal end of the housing 10, and an inner raised portion 16b that protrudes radially outward from the inner peripheral surface of the inner tube 12 toward the surface of the innermost layer of the hollow fiber membrane layer 30 and extends from the distal end to the proximal end of the housing 10. A plurality of raised portions 16 are formed on the housing 10. The raised portions 16 guide the flow direction of blood flowing through the blood chamber 40 in the longitudinal direction of the housing 10 (e.g., from the distal end to the proximal end).

[0035] As shown in Figure 3, the raised portions 16 can be formed so that their peaks 16c abut against the outer peripheral surface (surface of the outermost layer) of the hollow fiber membrane layer 30 or the inner peripheral surface of the core 20 around which the hollow fiber membranes 31 are wound. As a result, in the oxygenator 100, blood flow passages 18 are formed between adjacent raised portions 16 in the circumferential direction of the housing 10. The flow passages 18 extend in the longitudinal direction of the housing 10 and define the blood flow direction so that blood within the housing 10 flows from the distal end toward the proximal end of the housing 10. The flow passages 18 form a blood flow in the longitudinal direction from the distal end toward the proximal end of the housing 10, and function as a stagnation suppression portion that suppresses the formation of blood stagnation areas within the housing 10.

[0036] In this way, the artificial lung 100 can form a longitudinal blood flow from the tip end side to the base end side of the housing 10 in the outermost layer of the hollow fiber membrane layer 30 within the blood chamber 40 of the housing 10, thereby suppressing the formation of stagnation areas within the blood chamber 40 and improving antithrombotic properties.

[0037] Considering the formation of the flow passage 18 and the positional fixation of the hollow fiber membrane layer 30, the ridge 16 can also form the flow passage 18 by abutting the apex 16c with a portion of the hollow fiber membrane layer 30 or the core 20. The hollow fiber membrane layer 30 may be wound around the core 20 as shown in FIG. 1 , but it is preferable to form the hollow fiber membrane 31 by directly winding it around the inner tube 12. In this case, the core 20 is configured as part of the inner tube 12. It is sufficient for the ridge 16 to form a blood flow from the distal end to the proximal end of the housing 10 in the outermost or innermost layer of the hollow fiber membrane layer 30 within the blood chamber 40. Therefore, the ridge 16 may be positioned with a slight gap between the apex 16c and the hollow fiber membrane layer 30 or the core 20, so as not to impede the blood flow or form a stagnation area.

[0038] Next, the configuration of the outer protruding portion 16a and the inner protruding portion 16b that constitute the protruding portion 16 will be described.

[0039] As shown in FIG. 3 , the outer ridge 16 a and the inner ridge 16 b have a mountain-like shape with a smooth outer circumferential surface that gradually decreases in elevation from the center outward in a cross-sectional view perpendicular to the longitudinal direction. As shown in FIG. 3 , the outer ridge 16 a and the inner ridge 16 b are smoothly connected to adjacent ridges 16 in the circumferential direction. As shown in FIG. 3 , the outer ridge 16 a and the inner ridge 16 b can be formed in a wavy shape with continuous concave and convex shapes along the circumferential direction of the inner circumferential surface of the housing 10. This makes it difficult for blood to stagnate in the blood chamber 40 formed in the storage space 11 a, effectively enhancing antithrombotic properties. The shape of the ridges 16 is not limited to the wavy shape shown in FIGS. 2 and 3 , as long as they ridge at least radially inward from the inner circumferential surface of the housing 10 and are formed in multiple numbers extending from the distal end to the proximal end of the housing 10.

[0040] As shown in Figures 4A to 4C, the outer protrusions 16a may be formed in multiple portions, protruding radially inward from at least the inner peripheral surface of the outer tube 11 and extending from the tip end to the base end of the outer tube 11.

[0041] As shown in FIG. 4A, the outer protrusion 16a extends continuously from the tip end to the base end of the outer tube 11 along the longitudinal axis direction, and multiple outer protrusions 16a can be formed at predetermined intervals along the circumferential direction of the outer tube 11.

[0042] As shown in Figure 4B, in variant example 1, the outer protrusion 16a extends continuously from the tip end to the base end of the outer tube 11 at an angle with respect to the longitudinal axis direction, and multiple outer protrusions 16a can be formed at predetermined intervals along the circumferential direction of the outer tube 11.

[0043] Furthermore, as shown in Fig. 4C , as a second modification, the outer protrusions 16a can be formed discontinuously at predetermined intervals in the longitudinal direction rather than continuously from the tip to the base end of the outer tube 11. When the outer protrusions 16a are formed discontinuously as shown in Fig. 4C , it is preferable to form them in a staggered arrangement in the circumferential direction of the outer tube 11, as this facilitates the function of the flow passages 18. Note that Fig. 4C shows a configuration in which the outer protrusions 16a shown in Fig. 4A are formed discontinuously from the tip to the base end of the outer tube 11, but this configuration can also be applied to the configuration shown in Fig. 4B.

[0044] As shown in Figures 5A to 5C, the inner protrusions 16b may be formed in multiple portions, protruding radially outward from at least the outer peripheral surface of the inner tube 12 and extending from the tip end to the base end of the inner tube 12.

[0045] As shown in FIG. 5A, the inner protrusion 16b extends continuously from the tip end to the base end of the inner tube 12 along the longitudinal axis direction, and multiple protrusions can be formed at predetermined intervals along the circumferential direction of the inner tube 12.

[0046] As shown in Figure 5B, in variant example 1, the inner protrusion 16b extends continuously from the tip end to the base end of the inner tube 12 at an angle with respect to the longitudinal axis direction, and multiple inner protrusions 16b can be formed at predetermined intervals around the circumferential direction of the inner tube 12.

[0047] As shown in Fig. 5C , in Modification 2, the inner raised portions 16b are not formed continuously from the tip end to the base end of the inner tube 12, but can be formed discontinuously at predetermined intervals in the longitudinal direction. When the inner raised portions 16b are formed discontinuously as shown in Fig. 5C , it is preferable to form them in a staggered arrangement in the circumferential direction of the outer tube 11, as this facilitates the function of the flow passages 18. Note that Fig. 4C shows a configuration in which the outer raised portions 16a shown in Fig. 4A are formed discontinuously from the tip end to the base end of the outer tube 11, but this configuration can also be applied to the configuration shown in Fig. 4B.

[0048] 4A to 5C , the raised portion 16 forms a flow passage 18 that allows blood flowing within the blood chamber 40 to flow from one end of the housing 10 to the other end in the longitudinal direction, thereby suppressing the formation of stagnation areas and enhancing antithrombogenicity. Furthermore, from the viewpoint of increasing the flow rate of blood flowing around the hollow fiber membrane layer 30, it is preferable to provide both an outer raised portion 16 a and an inner raised portion 16 b, but a configuration in which only one of these is provided may also be used. In other words, providing only the outer raised portion 16 a can suppress blood stagnation at the contact point between the hollow fiber membrane layer 30 and the outer tube 11, while providing only the inner raised portion 16 b can suppress blood stagnation at the contact point between the hollow fiber membrane layer 30 and the inner tube 12 and near the flow path to the blood outlet port 15.

[0049] The raised portion 16 is integrally formed on the inner peripheral surface of the outer tube 11 or the outer peripheral surface of the inner tube 12. However, the raised portion 16 may be formed separately from the outer tube 11 or the inner tube 12 and fixed to the inner peripheral surface of the outer tube 11 or the outer peripheral surface of the inner tube 12 with an adhesive or the like.

[0050] Furthermore, when the outer ridge 16a and the inner ridge 16b have the configurations shown in Figures 4C and 5C, it is preferable to provide an R-shape in the portion facing the longitudinal direction so as not to interfere with blood flow in the longitudinal direction. This R-shape may be either convex or concave toward the hollow fiber membrane layer 30 as long as it does not interfere with blood flow in the longitudinal direction and allows blood to circulate smoothly. This allows the R-shape to form a smooth surface that blocks blood flow in the axial direction, thereby suppressing the occurrence of thrombus. Furthermore, when inserting or replacing the hollow fiber membrane layer 30, the smooth contact surface with the layer prevents deterioration of insertion ease and damage to the fibers.

[0051] The recess 17 is adjacent to the downstream end in the blood flow direction of the inner protrusion 16 b that is the inner periphery of the housing 10 , and is formed continuously in the circumferential direction of the inner periphery facing the blood outflow portion of the blood flow path 50 .

[0052] As shown in Fig. 6, the recess 17 is composed of a straight portion 17a whose outer diameter gradually decreases from the downstream end of the raised portion 16 in the blood flow direction, and a curved portion 17b that is disposed adjacent to the straight portion 17a and has an arc shape that extends radially outward with a predetermined radius of curvature. As shown in Fig. 6, one end of the straight portion 17a is disposed adjacent to the downstream end of the inner raised portion 16b in the blood flow direction, and the outer diameter gradually decreases radially inward toward the base end, and the other end is connected to the curved portion 17b. The curved portion 17b has one end that connects to the base end of the straight portion 17a, is curved in an arc shape that extends radially outward with a predetermined radius of curvature, and the other end is connected to the inner bottom portion 11c of the outer cylinder 11.

[0053] By providing the recess 17 at a position facing an outflow portion within the blood flow path 50 where the blood flow direction may suddenly change (e.g., a portion where the flow changes from along the longitudinal direction of the housing 10 to a direction intersecting the longitudinal direction), the blood can be guided in the flow direction while suppressing blood stagnation. As shown in FIG. 1 , the recess 17 can be positioned facing the inlet (proximal opening) of the blood outflow port 15, which is the outflow portion where the blood flow direction suddenly changes from the longitudinal direction to a direction intersecting the longitudinal direction. As a result, the blood flows along the longitudinal direction of the housing 10 and is then guided by the recess 17 to the proximal opening of the blood outflow port 15. Therefore, in the oxygenator 100, blood flows smoothly at the outflow portion within the blood flow path 50 where the blood flow direction may suddenly change, suppressing the formation of stagnation areas in areas where blood is likely to stagnate.

[0054] 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.

[0055] 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.

[0056] <Core> The core 20 has a cylindrical shape, and is accommodated 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 tube 12. The core 20 may be provided integrally with the inner tube 12. In this case, the hollow fiber membrane 31 is wound directly around the inner tube 12, and the inner tube 12 functions as the core 20.

[0057] The material constituting the core 20 is not particularly limited, but as with the inner tube 12, examples that can be used 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, polycarbonate, etc.

[0058] <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.

[0059] As shown in FIG. 1, the hollow fiber membrane layer 30 has a gas exchange section 32 .

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] Next, the flow of blood in the oxygenator 100 will be described.

[0065] 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 .

[0066] 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 .

[0067] The blood introduced into the blood chamber 40 flows between the inner peripheral surface of the outer tube 11 and the outermost layer of the hollow fiber membrane layer 30, between the outer peripheral surface of the inner tube 12 and the inner peripheral surface of the core 20 at the innermost layer of the hollow fiber membrane layer 30, and inside the hollow fiber membrane layer 30, expanding as it flows from the distal end side toward the proximal end side of the housing 10. 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.

[0068] 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 the flow passage 18 formed by the outer ridge 16a and flows through the outermost layer of the hollow fiber membrane layer 30 from the distal end to the proximal end of the housing 10. Blood flowing between the outer peripheral surface of the inner cylinder 12 and the inner peripheral surface of the core 20 in the innermost layer of the hollow fiber membrane layer 30 passes through the flow passage 18 formed by the inner ridge 16b and flows through the innermost layer of the hollow fiber membrane layer 30 from the distal end to the proximal end of the housing 10. Therefore, in the oxygenator 100, the formation of blood stagnation areas in the outermost and innermost layers of the hollow fiber membrane layer 30 is suppressed, making it less likely for thrombi to form.

[0069] 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.

[0070] Next, a method for manufacturing the oxygenator 100 will be described.

[0071] First, the core 20 is set on a connecting member connected to the motor of the manufacturing device, and while rotating the core 20, the hollow fiber membrane 31 is spirally wound around the outer periphery of the core 20. The number of hollow fiber membranes 31 extruded by the manufacturing device may be one or more (approximately two to six), but if one is extruded, the winding interval of the hollow fiber membrane 31 during winding can be adjusted as desired.

[0072] 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.

[0073] Then, the distal and proximal ends of the outer cylinder 11, the lid portion 13, etc. are attached, and the oxygenator 100 is obtained.

[0074] [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.

[0075] 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.

[0076] 7, 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.

[0077] The outer cylinder 11 of the housing 10 has a partition wall 11d that separates the gas exchange hollow fiber membrane layer 30 (first hollow fiber membrane layer 30A) and the heat exchange hollow fiber membrane layer 30 (second hollow fiber membrane layer 30B) within the storage space 11a that houses them.

[0078] 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.

[0079] A communication hole 19 that connects the two spaces separated by the partition wall 11 d is formed downstream of the partition wall 11 d in the blood flow direction. The communication hole 19 allows blood flowing through the second blood chamber 42 to flow into the first blood chamber 41. The communication hole 19 is an outlet for blood in the blood flow path 50 inside the housing 10.

[0080] 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. 7, 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.

[0081] From the viewpoint of improving the efficiency of gas exchange in the blood, the gas inlet port 10A is preferably disposed in a position opposite to the flow direction of blood flowing through the housing 10 so that gas can flow into the first blood chamber 41 (toward the tip end of the outer cylinder 11, which is downstream in the direction of blood flow). The gas outlet port 10B is preferably disposed in a position approximately opposite to the gas inlet port 10A in the longitudinal direction (toward the base end of the outer cylinder 11, which is 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. 7 and may be any positions that allow heat exchange of blood within the first blood chamber 41.

[0082] 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. 7 , and may be any positions that allow heat exchange of the blood in the second blood chamber 42.

[0083] In the oxygenator 100A of the second embodiment, the raised portion 16 is composed of an outer raised portion 16a and an inner raised portion 16b.

[0084] The outer protrusions 16a are formed on the inner circumferential surface of the outer cylinder 11 and the inner circumferential surface of the partition wall 11d of the outer cylinder 11. That is, one outer protrusion 16a is formed at a position facing the outermost layer of the first hollow fiber membrane layer 30A housed in the first blood chamber 41 that functions as the gas exchange section 32, and the other outer protrusion 16a is formed at a position facing the outermost layer of the second hollow fiber membrane layer 30B housed in the second blood chamber 42 that functions as the heat exchange section 33.

[0085] The inner protrusions 16b are formed on the outer peripheral surface of the inner cylinder 12 and the outer peripheral surface of the partition wall 11d of the outer cylinder 11. That is, in the oxygenator 100A of the second embodiment, as shown in Fig. 7 , one inner protrusion 16b is formed at a position facing the inner peripheral surface of the core 20 of the innermost layer of the first hollow fiber membrane layer 30A housed in the first blood chamber 41 that functions as the gas exchange section 32, and another inner protrusion 16b is formed at a position facing the inner peripheral surface of the core 20 of the innermost layer of the second hollow fiber membrane layer 30B housed in the second blood chamber 42 that functions as the heat exchange section 33.

[0086] The inner protrusion 16b only needs to be formed at a position opposite to the surface of the innermost layer of the first hollow fiber membrane layer 30A contained in the first blood chamber 41, i.e., on the outer peripheral surface of the partition wall 11d within the first blood chamber 41.

[0087] The recess 17 is disposed adjacent to the downstream end of the inner protrusion 16b in the blood flow direction. In the second embodiment, as shown in FIG. 7 , the recess 17 is formed on the proximal end side of the inner protrusion 16b formed on the outer peripheral surface of the inner cylinder 12, facing the communicating hole 19. The recess 17 is also formed on the distal end side of the inner protrusion 16b formed on the outer peripheral surface of the partition wall 11d, facing the proximal opening of the blood outlet port 15. The communicating hole 19 and the proximal opening of the blood outlet port 15 are both blood outlet portions in the blood flow path 50 within the housing 10, where the blood flow direction abruptly changes from the longitudinal direction to a direction intersecting the longitudinal direction. Therefore, the recess 17 prevents the formation of stagnation portions in the blood flowing from the second blood chamber 42 to the first blood chamber 41 and the blood flowing from the first blood chamber 41 to the blood outlet port 15 due to abrupt changes in flow direction.

[0088] Next, the flow of blood in the oxygenator 100A will be described.

[0089] 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.

[0090] First, blood flowing in from the blood inlet port 14 is guided to the second blood chamber 42 through the guide portion 14a.

[0091] The blood introduced into the second blood chamber 42 flows between the outer peripheral surface of the inner tube 12 and the core 20 in the innermost layer of the second hollow fiber membrane layer 30B, between the inner peripheral surface of the partition wall 11d and the outermost layer of the second hollow fiber membrane layer 30B, and through the inside of the second hollow fiber membrane layer 30B, expanding as it flows 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.

[0092] In the second blood chamber 42 of 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 passes through the flow passage 18 formed by the outer ridge 16a and flows through the outermost layer of the second hollow fiber membrane layer 30B from the distal end to the proximal end of the housing 10. Furthermore, blood flowing between the inner circumferential surface of the inner tube 12 and the inner circumferential surface of the core 20 in the innermost layer of the second hollow fiber membrane layer 30B passes through the flow passage 18 formed by the inner ridge 16b and flows through the innermost layer of the second hollow fiber membrane layer 30B from the distal end to the proximal end of the housing 10. Therefore, in the oxygenator 100A, the formation of blood stagnation areas in the outermost and innermost layers of the hollow fiber membrane layer 30 is suppressed, making it less likely for thrombi to form.

[0093] The blood that has passed through the second blood chamber 42 flows into the first blood chamber 41 through the communication hole 19 .

[0094] The blood that has flowed into the first blood chamber 41 expands as it flows between the inner peripheral surface of the outer cylinder 11 and the outermost layer of the first hollow fiber membrane layer 30A, between the outer peripheral surface of the partition wall 11d and the core 20 in the innermost layer of the first hollow fiber membrane layer 30A, and inside the first hollow fiber membrane layer 30A, from the base end side toward 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.

[0095] In the first blood chamber 41 of the oxygenator 100A, blood flowing between the inner circumferential surface of the outer cylinder 11 and the surface of the outermost layer of the first hollow fiber membrane layer 30A passes through the flow passage 18 formed by the outer ridge 16a and flows through the outermost layer of the hollow fiber membrane layer 30 from the base end to the tip of the housing 10. Furthermore, blood flowing between the outer circumferential surface of the partition wall 11d and the inner circumferential surface of the core 20 in the innermost layer of the first hollow fiber membrane layer 30A passes through the flow passage 18 formed by the inner ridge 16b and flows through the innermost layer of the first hollow fiber membrane layer 30A from the base end to the tip of the housing 10. Therefore, in the oxygenator 100A, the formation of blood stagnation areas in the outermost and innermost layers of the hollow fiber membrane layer 30 is suppressed, making it less likely for thrombi to form.

[0096] 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 19, and then flows in the longitudinal direction from the base end side to the tip end side of the housing 10, which is on the opposite side of the inflow direction of the blood inlet port 14, and flows out from the blood outlet port 15.

[0097] 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.

[0098] [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 formed by winding hollow fiber membranes and contained within the housing 10, in which blood flowing in through the blood inlet port 14 flows from one end of the housing 10 to the other end in the longitudinal direction and flows out through the blood outlet port 15, and the housing 10 has a plurality of raised portions 16 that protrude radially inward from the inner peripheral surface of the housing 10 toward the surface of the outermost layer of the hollow fiber membrane layer 30 and extend from the distal end to the proximal end of the housing 10.

[0099] The oxygenator 100 includes a raised portion 16 that directs the flow direction of blood between the housing 10 and the surface of the outermost layer of the hollow fiber membrane layer 30 from the distal end to the proximal end of the housing 10. The raised portion 16 increases the flow rate of blood flowing through the innermost layer of the hollow fiber membrane layer 30 within the housing 10 by directing the flow from one end to the other end in the longitudinal direction of the housing 10. Therefore, the oxygenator 100 can suppress the formation of blood stagnation areas in the outermost layer of the hollow fiber membrane layer 30, thereby enhancing antithrombotic properties.

[0100] Furthermore, the raised portions 16 of the oxygenator 100 may be formed so that the peaks 16c abut against the outer peripheral surface of the outermost layer of the hollow fiber membrane layer 30, and blood flow passages 18 may be formed between adjacent raised portions 16 in the circumferential direction of the housing 10. The flow passages 18 may also function as retention suppression sections that direct blood flow from the distal end to the proximal end of the housing 10.

[0101] With this configuration, the artificial lung 100 allows blood flowing through the blood chamber 40 of the housing 10 to flow through the circulation passage 18 from the tip end of the housing 10 to the base end, thereby suppressing the formation of stagnation areas within the housing 10 and improving antithrombotic properties.

[0102] Furthermore, the raised portions 16 of the artificial lung 100 may be formed so as to have a mountain shape with a smooth outer surface in which the amount of protrusion decreases from the center outward when viewed in a cross section perpendicular to the longitudinal direction, and may also be formed so as to be smoothly connected to adjacent raised portions 16 in the circumferential direction.

[0103] With this configuration, the oxygenator 100 can prevent blood flowing between the housing 10 and the hollow fiber membrane layer 30 from stagnating, thereby improving antithrombotic properties.

[0104] Furthermore, the raised portion 16 of the oxygenator 100 may be formed continuously or discontinuously from the distal end to the proximal end of the housing 10 .

[0105] Even if the raised portion 16 of the artificial lung 100 is formed continuously or discontinuously from the tip to the base of the housing 10, the blood flowing within the housing 10 can be made to flow from one end to the other in the longitudinal direction of the housing 10, thereby suppressing the formation of stagnation areas within the housing 10 and improving antithrombotic properties.

[0106] This application is based on Japanese Patent Application No. 2023-164699, filed on September 27, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0107] REFERENCE SIGNS LIST 10 Housing, 10A Gas inlet port, 10B Gas outlet port, 10C Heat transfer medium inlet port, 10D Heat transfer 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 Raised portion (16a Top), 17 Recess, 18 Flow passage, 19 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.

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 formed by winding a hollow fiber membrane and contained within the housing, wherein blood flowing in from the blood inlet port flows from one end of the housing in the longitudinal direction to the other end and flows out from the blood outlet port, and the housing has a plurality of raised portions that protrude radially inward from the inner surface of the housing toward the surface of the outermost layer of the hollow fiber membrane layer and extend from the tip end of the housing to the base end.

2. The artificial lung as described in claim 1, wherein the raised portions are formed so that their tops abut against the outer peripheral surface of the outermost layer of the hollow fiber membrane layer, and a blood flow passage is formed between adjacent raised portions in the circumferential direction of the housing.

3. The artificial lung according to claim 2, wherein the flow passage functions as a retention prevention section that prevents the formation of blood retention areas within the housing.

4. The artificial lung as described in claim 1, wherein the raised portion has a mountain-like shape having a smooth outer peripheral surface whose amount of protrusion decreases from the center outward when viewed in a cross section perpendicular to the longitudinal direction.

5. The artificial lung according to claim 4, wherein the raised portions are smoothly connected to adjacent raised portions in the circumferential direction.

6. An artificial lung as described in any one of claims 1 to 5, wherein the raised portion is formed continuously or discontinuously from the tip end to the base end of the housing.

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