Artificial lung

Abstract

To provide an artificial lung preventing thrombus formation from a high-density layer to an inner typical-density layer when the high-density layer is provided in a hollow fiber membrane layer.SOLUTION: A first hollow fiber membrane layer 90 of an artificial lung 10 has a first high-density layer 96 which is provided to an outer peripheral part of a first typical-density layer 94 and in which a first hollow fiber membrane 88 is wound at a higher density than in the first typical-density layer 94. When the resistance coefficient of the first high-density layer 96 to blood is defined as a first resistance coefficient K1, and the resistance coefficient of the first typical-density layer 94 to the blood is defined as a second resistance coefficient K2, the ratio of the first resistance coefficient K1 to the second resistance coefficient K2 is 2.0 or more.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an artificial lung for removing carbon dioxide from blood and adding oxygen to the blood via a hollow fiber membrane. [Background technology]

[0002] Patent Document 1 discloses a parallel flow oxygenator in which blood is circulated axially inside a hollow fiber membrane layer formed by radially wrapping hollow fiber membranes, thereby performing gas exchange and heat exchange with the blood.

[0003] The oxygenator of Patent Document 1 comprises a gas exchange section having a hollow fiber membrane that performs gas exchange with blood, first and second housings for accommodating the gas exchange section, and a rotary pump for circulating blood through the hollow fiber membrane. The first housing comprises a gas inlet for introducing gas into the first housing, and a gas outlet for discharging gas that has circulated through the gas exchange section to the outside. The second housing is disposed on the outer periphery of the first housing, and comprises a blood inlet for introducing blood, and a blood outlet for discharging blood that has undergone gas exchange. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] DE 10341221 A1 Summary of the Invention [Problem to be solved by the invention]

[0005] In parallel-flow oxygenators, blood flows axially along the first and second housings, which causes changes in the velocity distribution of the fluid and can cause flow stagnation in some places. This can lead to the problem that blood flow is stagnate in the gas exchange section, making it more likely to cause thrombus.

[0006] In order to solve these problems, the applicant has proposed an artificial lung (filed on the same day as this application) in which a high-density layer is provided in which hollow fibers are wound at a high density around a hollow fiber membrane layer, and a blood outlet space is provided between the housing and the high-density layer through which blood can flow in the axial direction. This proposal can prevent blood clots from forming on the outer periphery of the hollow fiber membrane. However, when a high-density layer is provided in the hollow fiber membrane layer, attention must also be paid to blood clot formation in the normal density layer inward from the high-density layer.

[0007] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0008] An aspect of the present invention is a hollow fiber membrane layer formed by winding a hollow fiber membrane, a housing having a blood inlet port, a blood outlet port, and a chamber for accommodating the hollow fiber membrane layer, the housing being formed into a cylindrical shape along an axial direction; In the oxygenator, blood flows through the storage chamber of the housing along the axial direction, The hollow fiber membrane layer has a normal density layer and a high density layer provided on the outer periphery of the normal density layer and in which the hollow fiber membrane is wound at a higher density than the normal density layer, The housing has a wall surrounding the densified layer and extending in the axial direction, a blood outflow space extending along the axial direction between the wall portion of the housing and the high density layer, through which the blood can flow along the axial direction; When the resistance coefficient of the high density layer to the blood is a first resistance coefficient and the resistance coefficient of the normal density layer to the blood is a second resistance coefficient, the ratio of the first resistance coefficient to the second resistance coefficient is 2.0 or more. Effect of the Invention

[0009] According to the present invention, the following effects can be obtained.

[0010] That is, the hollow fiber membrane layer has a high density layer wound more densely than the normal density layer and has a blood outflow space between the wall of the housing and the high density layer, so that the formation of a thrombus can be suppressed between the wall of the housing and the outer periphery of the hollow fiber membrane layer. By setting the ratio of the first resistance coefficient of the high density layer to the second resistance coefficient of the normal density layer for blood to 2.0 or more, the outflow amount of blood flowing from the normal density layer to the blood outflow space via the high density layer can be suppressed. Therefore, when blood flows through the hollow fiber membrane, a sufficient flow rate of blood can be secured in the normal density layer, and the formation of a thrombus in the normal density layer due to the provision of a blood outflow space is suitably suppressed. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an overall cross-sectional view of an artificial lung according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of the gas exchange section and the heat exchange section of the oxygenator of FIG. [Diagram 3] FIG. 3 is a table showing the experimental results obtained by changing the resistance coefficient ratio between the first high density layer and the first normal density layer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The oxygenator 10 according to this embodiment is a medical device that temporarily performs the function of the lungs during cardiac surgery or other operations or when the heart or lungs fail. That is, the oxygenator 10 is a device for regulating blood temperature, adding oxygen to blood, and removing carbon dioxide during extracorporeal circulation.

[0013] As shown in FIG. 1, the oxygenator 10 comprises a housing 12 , a heat exchange section 14 and a gas exchange section 16 .

[0014] The housing 12 is made of a hard resin material and has a housing body 18 that houses the heat exchange section 14 and the gas exchange section 16, a first cover member 20 disposed at one axial end of the housing body 18 (the end in the direction of the arrow A in FIG. 1), and a second cover member 22 disposed at the other axial end of the housing body 18 (the end in the direction of the arrow B in FIG. 1).

[0015] The housing body 18 is formed into a cylindrical shape along the axial direction (the direction of arrows A and B). The housing body 18 includes a core portion 24 that constitutes the central portion of the oxygenator 10, an outer cylinder portion 26 that is disposed on the outer circumferential side of the core portion 24, and an intermediate wall (wall portion) 28 that is disposed between the core portion 24 and the outer cylinder portion 26.

[0016] An annular, cylindrical storage chamber 30 extending in the axial direction (the direction of arrows A and B) is provided inside the housing body 18. The storage chamber 30 functions as a blood flow path through which blood flows.

[0017] The core portion 24 includes a first core 32 constituting one axial end of the core, and a second core 34 disposed at the other axial end of the first core 32. The first core 32 and the second core 34 are disposed spaced apart from each other in the axial direction (direction of arrows A and B).

[0018] The first core 32 has a tubular blood inlet portion 36 and an annular extension wall 38 extending radially outward from the blood inlet portion 36. The blood inlet portion 36 protrudes in one axial direction and has a blood inlet port 40 into which blood introduced from the patient via a blood removal flow path (not shown) flows in.

[0019] The second core 34 is formed in a cylindrical shape with a bottom, and has a cylindrical portion 42 and an occlusion portion 44 provided at one axial end of the cylindrical portion 42. The occlusion portion 44 faces the extending wall 38 and is disposed with a gap therebetween. A blood introduction passage 46 is formed between the occlusion portion 44 and the extending wall 38. The blood introduction passage 46 communicates with the blood inflow port 40 at the center, and blood is guided from the blood inflow port 40 radially outward through the blood introduction passage 46. The blood introduction passage 46 is connected near one axial end of the cylindrical portion 42 and communicates with the storage chamber 30.

[0020] The outer tube portion 26 is formed in a cylindrical shape along the axial direction (the direction of arrows A and B) and is disposed radially outwardly of the core portion 24 at a distance. An annular blood outlet portion 50 is provided on an outer peripheral wall (wall portion) 48 of the outer tube portion 26. The blood outlet portion 50 bulges radially outwardly from the outer peripheral wall 48. The blood outlet portion 50 communicates with a first storage portion 54 of the storage chamber 30, which will be described later. A blood outlet port 52 extending obliquely outward is connected to the blood outlet portion 50. The blood outlet portion 50 is connected to, for example, a blood outlet port 52 extending obliquely. The blood outlet port 52 is connected to a blood supply flow path to a living body, not shown.

[0021] The intermediate wall 28 has a cylindrical shape extending along the axial direction (the direction of arrows A and B), and is disposed at a distance radially outward from the tubular portion 42 of the core portion 24. The intermediate wall 28 is disposed between the core portion 24 and the outer tubular portion 26. The intermediate wall 28 surrounds a second hollow fiber membrane layer 102 of the heat exchange section 14, which will be described later. The intermediate wall 28 is parallel to the tubular portion 42 of the core portion 24 and an outer peripheral wall 48 of the outer tubular portion 26.

[0022] Between the intermediate wall 28 and the outer peripheral wall 48 of the outer cylinder portion 26, an annular first accommodation portion 54 constituting the accommodation chamber 30 is provided. That is, the first accommodation portion 54 is disposed on the outer peripheral side of the intermediate wall 28. The first accommodation portion 54 accommodates the cylindrical gas exchange portion 16. One axial end of the first accommodation portion 54 is sealed by an annular first sealing body 56a. The other axial end of the first accommodation portion 54 is sealed by an annular first sealing body 56b. The first sealing bodies 56a, 56b are formed from a urethane or resin material.

[0023] Between the intermediate wall 28 and the core portion 24, an annular second housing portion 58 constituting the housing chamber 30 is provided. The second housing portion 58 houses the cylindrical heat exchange portion 14. That is, the second housing portion 58 is disposed on the inner peripheral side of the intermediate wall 28. The intermediate wall 28 and the outer peripheral wall 48 are parallel to each other, and the first housing portion 54 and the second housing portion 58 are disposed in parallel to each other. One axial end of the second housing portion 58 is sealed by an annular second sealing body 60a. The other axial end of the second housing portion 58 is sealed by an annular second sealing body 60b. The second sealing bodies 60a and 60b are formed of urethane or a resin material. The positions of the gas exchange portion 16 and the heat exchange portion 14 are not particularly limited, and the positional relationship between the two inside the oxygenator 10 may be reversed.

[0024] An annular communication passage 62 that penetrates in the radial direction is formed at the other axial end of the intermediate wall 28. The communication passage 62 connects the first storage portion 54 and the second storage portion 58 to each other.

[0025] The first cover member 20 is attached to one axial end of the housing body 18 and fixed by adhesive or solvent bonding. The first cover member 20 covers one axial end of the heat exchange section 14 and the gas exchange section 16.

[0026] The first cover member 20 has a first cover body 64, a gas inlet portion 66, and a heat medium outlet portion 68. The first cover body 64 is formed in an annular shape covering one axial end of the housing body 18. The first cover body 64 has an annular first partition wall 70 that partitions a space on the other axial side of the first cover member 20. The first partition wall 70 extends from the inner surface of the first cover body 64 toward the other axial direction, and separates the first storage portion 54 and the second storage portion 58. The blood inlet portion 36 of the core portion 24 is disposed in the center of the first cover body 64.

[0027] The gas inlet 66 is formed in a tubular shape and is disposed in the first cover body 64 at a position facing one axial end of the first storage section 54. The gas inlet 66 protrudes from the first cover body 64 in one axial direction (the direction of the arrow A). The gas inlet 66 has a gas inlet port 72 that allows gas to flow into the inside of the first storage section 54. The gas inlet port 72 penetrates the first cover body 64 and communicates with the inner cavity of each of the first hollow fiber membranes 88 of the first hollow fiber membrane layer 90. The gas inlet port 72 is connected to a gas supply path (not shown) and supplies gas to the inside of the first storage section 54 through the gas supply path. The direction of the gas inlet 66 is not particularly limited, and although FIG. 1 shows an embodiment in which the gas inlet 66 protrudes in one axial direction (the direction of the arrow A), for example, the gas inlet 66 may protrude in the other axial direction (the direction of the arrow B).

[0028] The heat medium outlet portion 68 is formed in a tubular shape and is disposed in the first cover body 64 at a position facing one axial end of the first accommodation portion 54. The heat medium outlet portion 68 extends radially outward from the first cover body 64. The heat medium outlet portion 68 has a heat medium outlet port 74 for allowing the heat medium (e.g., water) circulated through the heat exchange portion 14 to flow out of the housing 12. The heat medium outlet port 74 penetrates the first cover body 64 and communicates with the inner cavity of each of the second hollow fiber membranes 100 of the second hollow fiber membrane layer 102. The arrangement of the heat medium outlet portion 68 is not particularly limited, and for example, the heat medium outlet portion 68 may be provided in the second cover body 76.

[0029] The second cover member 22 is attached to the other axial end of the housing body 18 and fixed by adhesive or solvent bonding. The second cover member 22 covers the other axial ends of the heat exchange section 14 and the gas exchange section 16.

[0030] The second cover member 22 has a second cover body 76, a gas outlet portion 78, and a heat medium inlet portion 80. The second cover body 76 is formed in an annular shape covering the other axial end of the housing body 18. The second cover body 76 has an annular second partition wall 82 that partitions a space on one side of the second cover member 22 in the axial direction.

[0031] The gas outlet 78 is formed in a tubular shape and is disposed in the second cover body 76 at a position facing the other axial end of the first storage section 54. The gas outlet 78 protrudes from the second cover body 76 in the other axial direction. The gas outlet 78 has a gas outlet port 84 that allows the gas circulated in the gas exchange section 16 to flow out of the housing 12. The gas outlet port 84 penetrates the second cover body 76 and communicates with the inner cavity of each of the first hollow fiber membranes 88 of the first hollow fiber membrane layer 90. The direction of the gas outlet port 84 is not particularly limited, and although FIG. 1 shows an embodiment in which the gas outlet port 84 protrudes in the other axial direction (arrow B direction), the present invention is not limited thereto, and the gas outlet port 84 may protrude in one axial direction (arrow A direction), for example.

[0032] The heat medium inlet section 80 is formed in a tubular shape and is disposed in the second cover body 76 at a position facing the other axial end of the second accommodation section 58. The heat medium inlet section 80 extends radially outward from the second cover body 76. The heat medium inlet section 80 has a heat medium inlet port 86 for allowing the heat medium to flow into the heat exchange section 14 of the second accommodation section 58. The heat medium inlet port 86 penetrates the second cover body 76 and communicates with the inner cavity of each second hollow fiber membrane 100 of the second hollow fiber membrane layer 102.

[0033] 1 and 2, the gas exchange section 16 is for supplying oxygen gas to the blood flowing through the blood flow path and removing carbon dioxide gas from the blood. The gas exchange section 16 has a cylindrical first hollow fiber membrane layer 90 in which a plurality of first hollow fiber membranes 88 are wound.

[0034] The first hollow fiber membrane 88 is tubular with a lumen. As the material of the first hollow fiber membrane 88, for example, a polymer material such as polypropylene, polyethylene, or polyolefin (polymethylpentene, etc.) is used.

[0035] Each first hollow fiber membrane 88 is wound around the outer surface of the intermediate wall 28 so as to extend over the entire axial length (direction of arrows A and B) of the gas exchange section 16. One axial end of each first hollow fiber membrane 88 penetrates the inside of the first sealing body 56a. An opening at one axial end of the first hollow fiber membrane 88 opens at one axial end of the first sealing body 56a and communicates with the gas inlet port 72. The other axial end of each first hollow fiber membrane 88 penetrates the inside of the first sealing body 56b. An opening at the other axial end of the first hollow fiber membrane 88 opens at one axial end of the first sealing body 56b and communicates with the gas outlet port 84. That is, gas flows through the lumen of the multiple first hollow fiber membranes 88. The first hollow fiber membranes 88 are configured to allow gas to pass through but not allow blood to pass through. A first blood passage 92 (see FIG. 2), which is a gap through which blood can flow, is formed outside the first hollow fiber membrane 88 inside the first housing portion 54. The first blood passage 92 is a gap formed between the first hollow fiber membranes 88 adjacent to each other.

[0036] The first hollow fiber membrane layer 90 includes a first general density layer 94 in which a plurality of first hollow fiber membranes 88 are wound, and a first high density layer 96 disposed on the outer periphery of the first general density layer 94. The first general density layer 94 and the first high density layer 96 together constitute the gas exchange section 16. The first high density layer 96 constitutes the outer periphery of the first hollow fiber membrane layer 90, and is a layer including the first hollow fiber membranes 88 disposed most radially outward in the gas exchange section 16. The first high density layer 96 is a layer in which the first hollow fiber membranes 88 are wound at a higher density than the first general density layer 94.

[0037] As a result of experiments conducted by the inventors and shown in Figure 3, it was confirmed that when blood flows through the first blood passage 92 of the gas exchange section 16, if the resistance coefficient of the first high density layer 96 to the blood is defined as a first resistance coefficient K1 and the resistance coefficient of the first normal density layer 94 to the blood is defined as a second resistance coefficient K2, it is preferable that the ratio of the first resistance coefficient K1 to the second resistance coefficient K2 (resistance coefficient ratio) be 2.0 or more.

[0038] Specifically, as can be seen from Fig. 3, when the resistance coefficient ratio (K1 / K2) obtained by dividing the first resistance coefficient K1 by the second resistance coefficient K2 is set to 1.0, no thrombus formation is confirmed in the first high-density layer 96, while the gas exchange efficiency during the exchange of carbon dioxide gas and oxygen gas in the blood is below the standard and does not reach the standard. When the resistance coefficient ratio is 2.0 or more, it is confirmed that no thrombus is formed in the first general-density layer 94. Therefore, by setting the resistance coefficient ratio to 2.0 or more, it is possible to suppress the formation of thrombus in the first general-density layer 94.

[0039] The first high density layer 96 is disposed in the gas exchange section 16 within a predetermined range radially inward from the outer periphery. The width dimension of the first high density layer 96 is constant along the axial direction (direction of arrows A and B) of the gas exchange section 16. When the gas exchange section 16 is accommodated in the first accommodation section 54, the first high density layer 96 is disposed facing the outer periphery wall 48 of the outer tubular section 26. A first blood outflow space 98 is formed between the first high density layer 96 and the outer periphery wall 48. At this time, a first ordinary density layer 94 is formed radially inward of the first high density layer 96. The width dimension of the first ordinary density layer 94 is also constant along the axial direction (direction of arrows A and B) of the gas exchange section 16.

[0040] The first blood outflow space 98 is a gap between the first high density layer 96 and the outer peripheral wall 48 in the radial direction, and is an annular space along the circumferential direction of the housing 12. The first blood outflow space 98 extends along the axial direction (the direction of arrows A and B) and is formed to allow blood to flow along the axial direction. The first blood outflow space 98 is formed over the entire length of the first high density layer 96 along the axial direction (the direction of arrows A and B).

[0041] The widthwise distance L of the first blood outflow space 98 along the radial direction is approximately constant along the axial direction of the housing body 18 and the gas exchange section 16. The widthwise distance L is the radial distance between the first high-density layer 96 and the outer circumferential wall 48 in the first hollow fiber membrane layer 90.

[0042] As shown in Figures 1 and 2, the heat exchange section 14 is for exchanging heat between the blood flowing through the blood flow path and the heat medium. The heat exchange section 14 is disposed on the inner circumferential side of the gas exchange section 16. The gas exchange section 16 and the heat exchange section 14 are disposed so as to overlap each other in the radial direction. The axial length of the heat exchange section 14 is the same as the axial length of the gas exchange section 16. The heat exchange section 14 has a cylindrical second hollow fiber membrane layer 102 in which a plurality of second hollow fiber membranes 100 are wound.

[0043] The second hollow fiber membrane 100 is tubular with a lumen. Each second hollow fiber membrane 100 is wound around the outer surface of the second core 34 so as to extend over the entire heat exchange section 14 along the axial direction (direction of arrows A and B). A second blood passage 104 (see FIG. 2) through which blood can flow is formed outside the second hollow fiber membrane 100 inside the second housing section 58. The second blood passage 104 is a gap formed between adjacent second hollow fiber membranes 100.

[0044] One axial end of each second hollow fiber membrane 100 penetrates the inside of the second sealed body 60a. The opening at one axial end of the second hollow fiber membrane 100 opens at one axial end of the second sealed body 60a and communicates with the heat medium outlet port 74. The other axial end of each second hollow fiber membrane 100 penetrates the inside of the second sealed body 60b. The opening at the other axial end of the second hollow fiber membrane 100 opens at the other axial end of the second sealed body 60b and communicates with the heat medium inlet port 86. That is, the heat medium flows through the lumen of the multiple second hollow fiber membranes 100. The second hollow fiber membrane 100 is configured to be impermeable to the heat medium and blood. The material of the second hollow fiber membrane 100 is the same as the material of the first hollow fiber membrane 88.

[0045] The second hollow fiber membrane layer 102 includes a second general density layer 106 in which a plurality of second hollow fiber membranes 100 are wound, and a second high density layer 108 disposed on the outer periphery of the second general density layer 106. The second general density layer 106 and the second high density layer 108 together form the heat exchange section 14. The second high density layer 108 is a layer of the second hollow fiber membranes 100 disposed radially outward in the heat exchange section 14. The second high density layer 108 is a layer in which the second hollow fiber membranes 100 are wound at a higher density than the second general density layer 106. The density of the second hollow fiber membranes 100 in the second high density layer 108 is higher than the density of the second hollow fiber membranes 100 in the second general density layer 106.

[0046] In addition, a high density layer in which the hollow fiber membrane is wound at a high density may be provided in each of the gas exchange section 16 having the first hollow fiber membrane layer 90 and the heat exchange section 14 having the second hollow fiber membrane layer 102, or a high density layer (first high density layer 96) may be provided only in the gas exchange section 16.

[0047] When the heat exchange section 14 is accommodated in the second accommodation section 58, the second high-density layer 108 is disposed facing the inner circumferential surface of the intermediate wall 28. A second blood outflow space 110 is formed between the second high-density layer 108 and the intermediate wall 28.

[0048] The second blood outflow space 110 is an annular space formed by the second high density layer 108 and the intermediate wall 28 being radially spaced apart from each other, along the circumferential direction of the housing 12. The second blood outflow space 110 extends along the axial direction (the direction of arrows A and B) and is formed to allow blood to flow along the axial direction. The second blood outflow space 110 is formed over the entire length of the second high density layer 108 along the axial direction.

[0049] Next, the operation of the oxygenator 10 will be described with reference to FIGS.

[0050] 1, a heat medium (e.g., water) is supplied from a heat medium supply source to a heat medium inlet port 86 of the oxygenator 10. The heat medium supplied to the heat medium inlet port 86 is introduced into the lumen of each second hollow fiber membrane 100 in the second housing section 58 from the other axial end of the heat exchange section 14.

[0051] Oxygen gas is supplied to the gas inlet port 72 of the oxygenator 10. The gas supplied to the gas inlet port 72 is introduced into the lumen of each first hollow fiber membrane 88 from one axial end of the gas-exchanging section 16 in the first housing section 54. The inflow direction of the gas is not particularly limited, and may be reversed.

[0052] Blood guided from the patient through the blood removal flow path is taken into the oxygenator 10 through the blood inlet port 40 by driving a pump (not shown). The blood supplied to the blood inlet port 40 is guided to the second storage section 58 through the blood introduction path 46. In the second storage section 58, the blood flows along the axial direction (direction of arrow B) from one axial end of the heat exchange section 14 to the other axial end. At this time, the blood flows through the second blood passages 104 formed between adjacent second hollow fiber membranes 100, whereby heat exchange occurs between the heat medium flowing through the lumen of each second hollow fiber membrane 100 and the blood flowing outside the second hollow fiber membranes 100.

[0053] 2, blood flowing through the heat exchange section 14 is divided into a main flow M1 that flows in the axial direction along the second blood passages 104 (gaps) in the second normal density layer 106, and a branch flow S1 that flows radially outward from the main flow M1 and flows through gaps between the second hollow fiber membranes 100 in the second high density layer 108 into the second blood outlet space 110. The branch flow S1 flows in the other axial direction (the direction of arrow B) along the second blood outlet space 110. The flow direction of the main flow M1 and the flow direction of the branch flow S1 are the same.

[0054] When blood flows between the second hollow fiber membranes 100 of the heat exchange section 14, a portion of the blood is circulated as a branch flow S1 through the second high density layer 108 to the second blood outlet space 110, thereby eliminating stagnation of blood flow at the outer periphery of the heat exchange section 14 and suppressing the formation of thrombi.

[0055] The blood that has undergone heat exchange in the heat exchange section 14 flows to the other axial end in the second storage section 58, and then flows radially outward through the annular communicating passage 62 to be supplied to the first storage section 54. In the first storage section 54, the blood flows along the axial direction (direction of arrow A) from the other axial end to one axial end of the gas exchange section 16. The blood flows through first blood passages 92 of each of the first hollow fiber membranes 88 that constitute the gas exchange section 16.

[0056] At this time, since the blood is introduced into the first storage section 54 through the communication passage 62, it tends to flow more easily toward the inner periphery of the gas exchange section 16 and less easily toward the outer periphery. In addition, in the first storage section 54, the flow rate of the blood slows down the closer it gets to the outer periphery wall 48. Furthermore, since the blood is supplied to the gas exchange section 16 after passing through the second hollow fiber membrane layer 102 of the heat exchange section 14, the flow rate in the gas exchange section 16 is slower than the flow rate when passing through the heat exchange section 14. Therefore, the flow of blood is likely to stagnate in the outer periphery of the gas exchange section 16, and thrombi are likely to occur.

[0057] 2, blood flowing through the gas exchange section 16 is divided into a main flow M2 that flows in the axial direction along the first blood passages 92 (gaps) in the first normal density layer 94, and a branch flow S2 that flows radially outward from the main flow M2 and flows into the first blood outlet space 98 through spaces between the first hollow fiber membranes 88 in the first high density layer 96. The branch flow S2 flows in one axial direction (the direction of arrow A) along the first blood outlet space 98. The flow direction of the main flow M2 and the flow direction of the branch flow S2 are the same.

[0058] In the gas exchange section 16, the gas flowing through the lumen of the first hollow fiber membrane 88 permeates the wall of the first hollow fiber membrane 88 and is supplied to the blood, and carbon dioxide gas in the blood permeates the wall of the first hollow fiber membrane 88 and is discharged to the inside of the first hollow fiber membrane 88. In other words, oxygen gas dissolves in the blood.

[0059] The blood that has undergone gas exchange flows toward one end in the axial direction and is led out from a blood outlet port 52 to a blood feed flow path (not shown) and returned to the patient.

[0060] On the other hand, the heat medium that has circulated through the heat exchange unit 14 and exchanged heat is led out from one axial end of the heat exchange unit 14 to the heat medium outlet port 74 and flows out to the outside of the oxygenator 10. The gas that has circulated through the gas exchange unit 16 is led out from the other axial end of the gas exchange unit 16 to the gas outlet port 84 and discharged to the outside of the oxygenator 10.

[0061] As described above, the embodiment of the present invention has a housing 12 and a first hollow fiber membrane layer 90 accommodated in the accommodation chamber 30 of the housing 12, and the first hollow fiber membrane layer 90 includes a first general density layer 94 and a first high density layer 96 provided on the outer periphery of the first general density layer 94 and in which the first hollow fiber membrane layer 90 is wound at a higher density than the first general density layer 94. A first blood outflow space 98 is provided between the outer periphery wall 48 of the housing 12 and the first high density layer 96, through which blood can flow in the axial direction.

[0062] As a result, when blood flows axially through the first hollow fiber membrane layer 90 of the gas exchange section 16, a portion of the blood is circulated through the first high-density layer 96 to the first blood outflow space 98, thereby preventing the formation of a blood clot between the outer wall 48 of the housing 12 and the outer periphery of the first hollow fiber membrane layer 90.

[0063] By providing the first high density layer 96, when blood flows along the axial direction of the first hollow fiber membrane 88, the outflow amount of blood (branch flow S2) flowing from the first regular density layer 94 to the first blood outlet space 98 is prevented from becoming too large. Therefore, the flow rate of blood in the first regular density layer 94 can be appropriately maintained, and the gas exchange efficiency between blood and gas in the first hollow fiber membrane layer 90 can be maintained.

[0064] The heat exchange section 14 has a second hollow fiber membrane 100, which includes a second general density layer 106 and a second high density layer 108 provided on the outer periphery of the second general density layer 106 and in which the second hollow fiber membrane 100 is wound at a higher density than the second general density layer 106. A second blood outflow space 110 is provided between the intermediate wall 28 of the housing 12 and the second high density layer 108, through which blood can flow in the axial direction.

[0065] As a result, when blood flows axially through the second hollow fiber membrane layer 102 of the heat exchange section 14, a portion of the blood is circulated into the second blood outlet space 110, thereby preventing the formation of a blood clot between the intermediate wall 28 of the housing 12 and the outer periphery of the second hollow fiber membrane layer 102.

[0066] By providing the second high density layer 108, it is possible to prevent the outflow amount of blood (branch flow S1) flowing from the second regular density layer 106 to the second blood outlet space 110 from becoming too large when blood flows along the axial direction of the second hollow fiber membrane 100. Therefore, it is possible to appropriately maintain the flow rate of blood in the second regular density layer 106, and to maintain the heat exchange efficiency between the blood and the heat medium in the second hollow fiber membrane layer 102.

[0067] By setting the ratio of the first resistance coefficient K1 of the first high density layer 96 to the second resistance coefficient K2 of the first regular density layer 94 to be 2.0 or more, it is possible to suppress a decrease in the flow rate of blood that becomes the main stream M2, and to ensure a sufficient flow rate of the main stream M2. This makes it possible to maintain the efficiency of gas exchange between blood and gas through each of the first hollow fiber membranes 88 of the first regular density layer 94.

[0068] In the first hollow fiber membrane layer 90, by setting the ratio of the first resistance coefficient K1 of the first high density layer 96 to the second resistance coefficient K2 of the first general density layer 94 to be 2.0 or more, the first high density layer 96 can control the outflow amount of blood from the first general density layer 94 to the first blood outflow space 98 to an appropriate amount. As a result, a sufficient blood flow rate is ensured in the first general density layer 94 of the first hollow fiber membrane layer 90, and the formation of thrombi in the first general density layer 94 is suitably suppressed.

[0069] The above embodiment can be summarized as follows.

[0070] The above embodiment includes a hollow fiber membrane layer (90, 102) formed by winding a hollow fiber membrane (88, 100), a housing (12) formed in a cylindrical shape along an axial direction, the housing having a blood inlet port (40), a blood outlet port (52), and a chamber (30) for accommodating the hollow fiber membrane layer; In an oxygenator (10) in which blood flows through the storage chamber of the housing along the axial direction, The hollow fiber membrane layer includes a normal density layer (94, 106) and a high density layer (96, 108) provided on the outer periphery of the normal density layer and in which the hollow fiber membrane is wound at a higher density than the normal density layer, The housing has a wall (28, 48) surrounding the densified layer and extending in the axial direction; a blood outflow space (98, 110) extending along the axial direction between the wall portion of the housing and the high density layer, through which the blood can flow along the axial direction; When the resistance coefficient of the high density layer to the blood is a first resistance coefficient (K1) and the resistance coefficient of the normal density layer to the blood is a second resistance coefficient (K2), the ratio (K1 / K2) of the first resistance coefficient to the second resistance coefficient is 2.0 or more.

[0071] The hollow fiber membrane layer is a gas exchange section (16) that performs gas exchange with the blood, The wall portion is an outer peripheral wall (48) that is provided on the outer periphery of the storage chamber, to which the blood outlet port is connected and that surrounds the high density layer of the hollow fiber membrane layer.

[0072] The blood outflow space is annular along the circumferential direction of the housing.

[0073] The blood outflow space is disposed along the entire axial length of the dense layer.

[0074] The present invention is not limited to the above-described embodiment, and various configurations can be adopted without departing from the gist of the present invention. [Explanation of symbols]

[0075] 10... Oxygenator 12... Housing 14...Heat exchange section 16...Gas exchange section 28... intermediate wall 40... blood inlet port 48...Outer wall 52...Blood outlet port 88…First hollow fiber membrane 90…First hollow fiber membrane layer 94…First general density layer 96…First high density layer 98…First blood outflow space 100…Second hollow fiber membrane 102…Second hollow fiber membrane layer 106…Second general density layer 108…Second high density layer 110…Second blood outflow space

Claims

1. A hollow fiber membrane layer formed by winding a hollow fiber membrane; a housing having a blood inlet port, a blood outlet port, and a chamber for accommodating the hollow fiber membrane layer, the housing being formed into a cylindrical shape along an axial direction; In the oxygenator, blood flows through the storage chamber of the housing along the axial direction, The hollow fiber membrane layer has a normal density layer and a high density layer provided on the outer periphery of the normal density layer and in which the hollow fiber membrane is wound at a higher density than the normal density layer, The housing has a wall surrounding the densified layer and extending in the axial direction, a blood outflow space extending along the axial direction between the wall portion of the housing and the high density layer, through which the blood can flow along the axial direction; An artificial lung, wherein when a resistance coefficient of the high density layer to the blood is a first resistance coefficient and a resistance coefficient of the normal density layer to the blood is a second resistance coefficient, the ratio of the first resistance coefficient to the second resistance coefficient is 2.0 or more.

2. 2. The oxygenator of claim 1, The hollow fiber membrane layer is a gas exchange section that performs gas exchange with the blood, The wall portion is an outer circumferential wall provided on the outer periphery of the storage chamber, to which the blood outlet port is connected and which surrounds the high density layer of the hollow fiber membrane layer.

3. 3. The oxygenator according to claim 1, An oxygenator, wherein the blood outflow space is annular along the circumferential direction of the housing.

4. The artificial lung according to any one of claims 1 to 3, An oxygenator, wherein the blood outflow space is disposed over the entire axial length of the dense layer.

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