Filter applicable for drip chamber

Abstract

This disclosure aims to provide a filter (10) for a drip chamber, comprising: a top plate portion (11), a lower ring (12), a plurality of ribs (13) connecting the top plate portion (11) and the lower ring (12) and forming a plurality of slits (15) between them, and an intermediate ring (14) connecting the ribs to each other and extending in the circumferential direction. The ribs (13) have an outer peripheral portion (13a) and a triangular inner peripheral portion (13b), the angle between the direction in which the side of the inner peripheral portion (13b) extends and the radial direction is greater than the angle between the direction in which the side of the outer peripheral portion (13a) extends and the radial direction, and the radial thickness of the intermediate ring (14) is thinner than the radial thickness of the ribs (13) located at the formation position of the intermediate ring (14).

Description

Technical Field

[0001] This disclosure relates to a filter for an infusion chamber. Prior Technology

[0002] The infusion chamber of the extracorporeal circulation circuit is equipped with a filter to remove blood clots or foreign objects from the blood. Molded filters and mesh filters are the main types of filters used in the infusion chamber.

[0003] Whether molded or mesh, filters aim to effectively remove impurities while ensuring smooth blood flow and easy removal of air bubbles during priming. Stagnation due to impaired blood flow can easily lead to clotting in that area. Furthermore, poor air bubble removal reduces operability during priming. Using the filter with trapped air bubbles can further impede blood flow and cause clotting.

[0004] Therefore, various studies have been conducted on the shapes of different filters in an attempt to ensure good blood flow and rapid expulsion of air bubbles. For example, in the case of molded filters, studies have been conducted on how to make the upper surface of the transverse component forming the slits inclined to allow blood to flow smoothly in the slit portion (for example, see Patent Document 1). Furthermore, in the case of mesh filters, attempts have been made to combine them with support components to prevent blood from becoming trapped in a three-dimensional shape (for example, see Patent Document 2).

[0005] Patent Document 1: Japanese Patent Publication No. 2002-525192

[0006] Patent Document 2: Japanese Patent Application Publication No. 9-140788 Summary of the Invention

[0007] -The technical problem the invention aims to solve-

[0008] However, conventional filters do not take into account the overall effect of transverse components on blood retention. When a surface intersects the direction of blood flow, blood retention is affected not only by the upstream surface but also by the overall structure. For example, a pocket-like area may form directly below the transverse component due to stagnant blood flow. Even if the upper surface of the transverse component is sloped, it is difficult to prevent retention in the area directly below it. Moreover, not only transverse components, but also the lower end face of the ribs and the back side of the top plate can contribute to retention, but these factors are not considered.

[0009] For mesh filters with support components, air bubble retention on the non-mesh top surface is also a significant problem. Furthermore, the process of assembling the support component and the mesh is a major contributor to increased costs. Research has been conducted on integrally molding the mesh filter and support component using insert molding, but this requires highly advanced molding technology. Moreover, the retention problem also occurs during insert molding.

[0010] The purpose of this disclosure is to provide a filter for an infusion chamber that enables smooth blood flow and minimizes blood stagnation.

[0011] -Technical means for solving technical problems-

[0012] In a first aspect of the drip chamber filter disclosed herein, a top plate portion, a lower ring, a plurality of ribs, and an intermediate ring are included. The plurality of ribs connect the top plate portion and the lower ring, and a plurality of slits are formed between the plurality of ribs. The intermediate ring connects the ribs to each other in the circumferential direction. The circumferential width of the ribs decreases as they approach the radially inner side. Each rib has an outer peripheral portion and a triangular inner peripheral portion. The angle between the direction in which the side of the inner peripheral portion extends and the radial direction is greater than the angle between the direction in which the side of the outer peripheral portion extends and the radial direction. The radial thickness of the intermediate ring is thinner than the radial thickness of the ribs located at the formation position of the intermediate ring.

[0013] According to the first aspect of the drip chamber, the radial thickness of the intermediate ring is thinner than the radial thickness of the rib located at the formation position of the intermediate ring, thus reducing the area prone to stagnation hidden under the intermediate ring. Therefore, blood is less likely to stagnate due to the intermediate ring. Since the inner circumference of the rib is a triangular shape with the angle between its lateral extension direction and the radial direction being larger than the angle between the lateral extension direction and the radial direction of its outer circumference, the width of the slit in the inner circumference of the rib is wider. Therefore, blood can flow smoothly within the slit, further reducing the likelihood of stagnation.

[0014] In a second aspect of a filter for a drip chamber, there are a top plate, a lower ring, and a plurality of ribs. The plurality of ribs connect the top plate and the lower ring. A plurality of slits are formed between the plurality of ribs. The top plate has an inclined lower surface that becomes lower towards the center and a top plate opening that runs vertically through the top plate.

[0015] In a second aspect of the filter for the drip chamber, since downward blood flow along the inclined lower surface of the top plate is more likely to occur, retention is less likely to occur compared to the case where the lower surface of the top plate is perpendicular to the blood flow. Since the inflow of blood from the top plate opening also produces downward flow, retention can be reduced across the entire lower surface of the top plate.

[0016] In a second aspect of the filter for the infusion chamber, the top plate may also have an inclined upper surface that slopes downwards towards the center. This structure allows for easy guidance of blood into the opening of the top plate.

[0017] In a second aspect of the filter for the drip chamber, the top plate opening can be formed in a radial shape with a radial length longer than its circumferential width. By adopting such a structure, blood flowing from the upper surface of the top plate towards the center can easily flow into the top plate opening, thus further reducing the likelihood of retention.

[0018] In a third aspect of a filter for a drip chamber, there is a top plate, a lower ring, and a plurality of ribs. The plurality of ribs connect the top plate and the lower ring. A plurality of slits are formed between the plurality of ribs. The ribs have an inclined region at their lower ends. The radial thickness of the inclined region gradually decreases downward to form a space on the lower side.

[0019] According to a third aspect of the filter for the infusion chamber, the ribs have an inclined region where the radial thickness gradually decreases downwards, so the lower end face of the ribs will not be perpendicular to the blood flow, making retention less likely to occur. Since a space is formed on the lower side of the ribs, the connection between the lower end of the filter and the chamber body will not be stepped, further reducing the likelihood of retention.

[0020] In a third aspect of the filter for the drip chamber, an intermediate ring is also included, formed between the top plate and the lower ring; the outer circumferential surface of the ribs can have a stepped portion that protrudes radially outward at the position where it intersects with the intermediate ring. By adopting such a structure, deformation of the ribs can be easily suppressed, making the circumferential width of the slits uniform, thereby improving the function of preventing blood clots, etc.

[0021] In a fourth aspect of the filter for drip chambers disclosed herein, a mesh filter and a filter holding portion for holding the mesh filter in a cylindrical shape are included; the filter holding portion has a top plate portion, a lower ring, and a support portion connecting the top plate portion and the lower ring; the lower surface of the top plate portion is highest at its outer edge, and the top plate portion has a top plate opening that extends vertically; the top plate opening has a minimum gap width at its lower end that is smaller than that at its upper end; the inner surface of the mesh filter is fixed in close contact with the outer surface of the filter holding portion.

[0022] In the fourth aspect of the filter for the infusion chamber, since the lower surface of the top plate is highest at the outer edge, no upward protrusion causing blood stagnation is formed at the upper end of the filter, thus suppressing stagnation. The top plate has a through-hole opening, with a smaller minimum gap width at the lower end than at the upper end. Therefore, it has a high ability to prevent blood clots or foreign objects from passing through, and air bubbles are easily expelled during pre-filling. Because the inner surface of the mesh filter is fixed tightly against the outer surface of the filter holder, it is easy to install the mesh filter onto the filter holder, and the mesh filter is not easily deformed, allowing blood to pass through smoothly.

[0023] In a fourth aspect of the filter for the drip chamber, the top plate opening has a plurality of openings formed on the circumference surrounding the center of the top plate. The outer edge wall of the opening is a vertical surface, while the central wall is an inclined surface that slopes towards the outer edge as it descends. By employing this structure, the thickness of the outer edge of the top plate can be made uniform, suppressing deformation during molding. Therefore, the mesh filter can be easily fixed to the outer surface of the top plate.

[0024] In a fourth aspect of the filter for the drip chamber, the aforementioned top plate may have a lower surface protrusion that extends from the top plate opening toward the center of the top plate and gradually increases in height. By adopting such a structure, air bubbles reaching the top plate can easily move to the outer edge where the top plate opening is located, and air bubbles can be easily removed.

[0025] In the fourth aspect of the filter for the infusion chamber, the outer diameter of the lower ring can be the same as the outer diameter of the top plate. By adopting such a structure, the mesh filter can be fixed in a cylindrical shape, and the amount of blood passing through the mesh filter is approximately constant. Therefore, blood is less likely to stagnate in the filter, and coagulation can be inhibited.

[0026] In a fourth aspect of the filter for drip chambers, it may also have a flange portion that protrudes radially outward from the lower part, and the flange portion has a notch on its outer peripheral surface, the notch portion being arranged in a manner that aligns with the support portion in the circumferential direction. With such a structure, it is easy to clamp the filter holder portion with a clamp and rotate it, so that the filter screen is wound around the filter holder portion and fixed tightly against the filter holder portion.

[0027] -The Effects of the Invention-

[0028] According to the filter disclosed herein, retention in filters used in drip chambers is less likely to occur. Simple Explanation of the Diagram

[0029] Figure 1 is a cross-sectional view showing the drip chamber as described in the first embodiment. Figure 2 is a side view showing the filter in relation to the first embodiment. Figure 3 is a top view showing the filter in relation to the first embodiment. Figure 4 is a cross-sectional view showing the filter in relation to the first embodiment. Figure 5 is a cross-sectional view showing the ribs in an enlarged form. Figure 6 is a sectional view taken along line VI-VI in Figure 3. Figure 7 is an enlarged cross-sectional view showing the fitting part of the filter and the chamber body. Figure 8 is a cross-sectional view showing the enlarged opening in the top plate. Figure 9 is a cross-sectional view showing the drip chamber as described in the second embodiment. Figure 10 is a perspective view showing the filter related to the second embodiment. Figure 11 is a perspective view showing the filter holding part related to the second embodiment. Figure 12 is a sectional view taken along line XII-XII in Figure 11. Figure 13 is a sectional view taken along line XIII-XIII in Figure 11. Figure 14 is a cross-sectional view taken along line XIV-XIV in Figure 11. Implementation

[0030] As shown in Figure 1, the drip chamber of the first embodiment has a chamber body 200 and a filter 10 housed therein. The chamber body 200 has a cylindrical portion 201 and an upper cover 203 mounted on the upper part of the cylindrical portion 201. The upper cover 203 has a plurality of ports 231 for connecting hoses 301. The number and arrangement of the ports 231 on the upper cover 203 are not particularly limited. The ports 231 may also be located on the side of the upper cover 203 or on the side of the cylindrical portion 201. The lower end of the cylindrical portion 201 tapers downwards, and a hose 302 is connected to the lower end. The filter 10 is embedded in the lower end of the cylindrical portion 201. It should be noted that although the example shown is a chamber body formed by the upper cover and the cylindrical portion, a structure formed by more components is also possible.

[0031] As shown in Figures 2 to 8, the filter 10 is a molded filter, having a top plate portion 11, a lower ring 12, and a plurality of ribs 13. The ribs 13 connect the top plate portion 11 and the lower ring 12, and slits 15 are formed between adjacent ribs 13 as openings.

[0032] Two intermediate rings 14 are formed between the top plate portion 11 and the lower ring 12, connecting the ribs 13 circumferentially. Therefore, the slit 15 is divided into three parts in the height direction by the intermediate rings 14. Each part divided in the height direction of the slit 15 is a longitudinally elongated shape with a height sufficiently large compared to its circumferential width, so that the direction of extension of the longitudinally elongated slit 15 is not orthogonal to the direction of blood and priming liquid flow. Bubbles trapped in the slit 15 are pushed by the liquid flow and move vertically within the slit 15, thus facilitating bubble passage and improving bubble detachment.

[0033] By forming the intermediate ring 14, deformation of the rib 13 can be easily suppressed, ensuring a uniform width of the slit 15. The number of intermediate rings 14 can be appropriately selected based on the height of the filter 10, and can be one or more. However, from the viewpoint of preventing air bubbles from becoming trapped, the length of the slit 15 divided in the height direction by the intermediate ring 14 is preferably 10% or more, and more preferably 20% or more, of the height of the filter 10. It should be noted that if deformation of the rib 13 can be sufficiently prevented, the intermediate ring 14 may not be required.

[0034] As shown in Figure 5, the rib 13 has an outer peripheral surface extending circumferentially and a side surface extending radially inward. The rib 13 is cylindrical, with its circumferential width decreasing towards the radially inward side. The cross-section of the rib 13 is approximately pentagonal, formed by an outer peripheral portion 13a that is approximately isosceles trapezoidal and an inner peripheral portion 13b that is approximately triangular. The angle θ2 between the side surface extension direction of the inner peripheral portion 13b and the radial direction is greater than the angle θ1 between the side surface extension direction of the outer peripheral portion 13a and the radial direction. As a result, the circumferential width of the slit 15 formed between the ribs 13 is longer radially inward than radially outward. In this embodiment, the circumferential width of the slit 15 remains approximately constant in the outer peripheral portion, or decreases slightly towards the radially inward side, while the circumferential width of the slit 15 in the inner peripheral portion 13b increases radially inward. It should be noted that the circumferential width of the slit 15 can be appropriately determined according to the required characteristics. For example, it can be about 0.1mm to 0.5mm on the outer circumferential surface and about 0.1mm to 2.0mm on the inner circumferential surface. The number of ribs 13 can be appropriately selected taking into account the slit width and the diameter of the filter 10.

[0035] By shaping the cross-section of rib 13 into a form consisting of an outer periphery 13a that is approximately isosceles trapezoidal and an inner periphery 13b that is approximately triangular, this shape increases strength and reduces deformation compared to ribs with a roughly triangular cross-section, while maintaining the same radial thickness. Unlike ribs with a roughly triangular cross-section, this shape allows for a portion with a constant slit width, thus enhancing the ability to prevent foreign objects from entering. On the other hand, compared to ribs with a roughly isosceles trapezoidal cross-section, the slit width is increased radially inward, facilitating blood flow and reducing the likelihood of stagnation. Since the angle between the outer periphery and the side surface of the rib is larger than that of a rib with a roughly triangular cross-section, edge damage to blood cells is less likely to occur. It should be noted that the inner end of the inner periphery 13b can be formed with a slightly rounded corner.

[0036] The intermediate ring 14 is a significant obstacle to blood flowing from top to bottom. Therefore, a bag-like area of ​​flow stagnation easily forms below the intermediate ring 14. When the width of the slit 15 gradually increases towards the center, if the intermediate ring 14 exists radially throughout the rib 13, the portion of the intermediate ring 14 that fills the slit 15 becomes larger, making stagnation more likely. In this embodiment, the radial thickness of the intermediate ring 14 is thinner than the radial thickness of the rib 13 at the location where the intermediate ring 14 is formed. The intermediate ring 14 is not present in the inner circumference 13b, but only at the outer edge of the outer circumference 13a. Since the intermediate ring 14 connects to the narrow circumferentially wide outer circumferential portion 13b of the slit 15, the portion of the intermediate ring 14 that fills the slit 15 is reduced compared to an intermediate ring that connects to the entire radial width of the rib 13, thus making stagnation less likely.

[0037] As shown in Figure 6, a step is formed on the outer circumferential surface of the rib 13 at the location where the intermediate ring 14 is formed. However, no step is formed on the inner circumferential surface of the rib 13 at the location where the intermediate ring 14 is formed. Inside the filter 10, no step is formed on the rib 13; instead, it is connected flatly, thus allowing for smooth blood flow and reducing the likelihood of stagnation. The ability to remove air bubbles is also improved. While a structure with a step on the outer circumferential surface of the rib 13 can easily improve the strength of the filter 10, it is also possible to omit the step. Alternatively, a structure with several steps on the inner side of the rib 13 can also be used.

[0038] In this embodiment, the rib 13 has an inclined region 18 at its lower end, the radial thickness of which gradually decreases downwards, becoming approximately zero near the lower end of the lower ring 12. As shown in FIG7, by forming the inclined region 18, a space 19 is created on the lower side of the rib 13. The filter 10 is generally fixed to the chamber body 200 by inserting the lower ring 12 into the groove 201a formed in the cylindrical portion 201. Therefore, the inclined surface forming the inclined region 18 is connected to the inner wall surface of the chamber body in a smooth manner with approximately no steps. In the absence of the inclined region 18, where the radial thickness of the rib 13 is uniform up to the lower end, the lower end surface of the rib 13 becomes a surface approximately orthogonal to the flow direction, creating a step at the lower end of the rib 13. In this situation, if the lower end of the rib 13 is aligned with the lower end of the lower ring 12, and the lower surface of the groove 201a is extended to the inner circumferential end of the rib 13, a step will not be formed at the lower end of the rib 13, but the lower end of the slit 15 will be blocked, thus forming a step. Any step can cause blood stagnation. However, as shown in FIG7, the rib 13 of this embodiment can prevent the formation of a step at the lower end of the rib 13, thereby suppressing stagnation. It should be noted that in this embodiment, the upper end of the inclined region 18 is consistent with the upper end of the lower ring 12, but they may not be consistent. The position where the radial thickness of the lower ring 12 is 0 may not be completely consistent with the lower end of the lower ring 12. The radial thickness of the rib 13 may not be completely 0.

[0039] The inner circumferential surface of the lower ring 12 is preferably connected to the outer circumferential surface of the rib 13 without any steps. This prevents the lower end of the slit 15 from being blocked by the upper surface of the lower ring 12, thus reducing the likelihood of stagnation. In this embodiment, a notch 16 is formed on the outer circumferential surface of the lower ring 12. The notch 16 corresponds to a gate portion for resin injection during molding, and its recessed shape prevents gate burrs from protruding from the outer circumferential surface of the lower ring 12.

[0040] As shown in Figure 8, in this embodiment, the lower surface 22 of the top plate portion 11 is an inclined lower surface that becomes increasingly lower towards the center. Air bubbles moving upwards inside the filter 10 and reaching the top plate portion 11 are guided radially outward by the inclined lower surface 22 of the top plate portion 11, which gradually rises from the center towards the outer edge. In the filter 10 of this embodiment, the slit 15 extends to the lower surface 22 of the top plate portion 11. Therefore, air bubbles reaching the outer edge of the top plate portion 11 can easily be discharged outside the filter through the slit 15. During use, blood flowing into the filter 10 from the upper end of the slit 15 flows downwards along the inclined lower surface 22, thus ensuring smooth blood flow on the lower side of the top plate portion 11 and preventing stagnation.

[0041] The height difference h1 between the center and the outer edge of the lower surface 22 of the top plate 11 is not particularly limited, but from the viewpoint of optimizing bubble discharge, it is preferably about 1.6 mm. However, the lower surface 22 of the top plate 11 is not limited to an inclined surface, and can also be a horizontal surface without height difference.

[0042] In this embodiment, the upper surface 21 of the top plate portion 11 is also recessed in the center, and at least a portion of the upper surface 21 is an inclined upper surface. In this embodiment, since the inclination of the inclined portion of the upper surface 21 is approximately the same as the inclination of the lower surface 22, the thickness of the top plate portion 11 can be approximately equal from the center to the outer edge. By making the thickness of the top plate portion 11 approximately equal, sink marks are less likely to occur during injection molding, improving molding accuracy. Therefore, the width of the slit 15 can be kept consistent, achieving a high blocking function against blood clots. The injection pressure during injection molding can also be reduced. If the injection pressure is high, burrs are more likely to be generated in the fine ribs 13, and the burrs in the ribs 13 can cause hemolysis. However, the inclination of the upper surface 21 of the top plate portion can also be inconsistent with the inclination of the lower surface 22. The upper surface 21 can also be a horizontal surface without any height difference.

[0043] In this embodiment, a top plate opening 17 extending vertically is formed on the top plate portion 11. During pre-filling, air bubbles are also discharged from the top plate opening 17 to the outside of the filter. During use, blood flows into the filter 10 not only from the slit 15 but also from the top plate opening 17. This generates a downward flow on the lower side of the top plate portion 11, reducing stagnation on the lower side of the top plate portion 11. In this embodiment, the top plate opening 17 is formed radially and is approximately rectangular with a radial length longer than its circumferential width. By forming such a shape, downward flow can be generated more easily. It should be noted that the shape of the opening surface of the top plate opening 17 is not limited to a generally rectangular shape; it can also be approximately triangular or approximately elliptical, etc., with a radial length longer than the maximum value of the circumferential width.

[0044] Furthermore, three top plate openings 17 are formed radially from the center of the top plate portion 11. By forming such a structure, the material can be evenly distributed, making it less likely for residue to accumulate. It should be noted that the number of top plate openings 17 can be one, two, or more than four, and the top plate openings 17 are not limited to a radial arrangement, but can also be formed along the circumferential direction.

[0045] The top plate opening 17 is formed to gradually widen from the bottom to the top, and the radially outer hole wall 17b has a steeper inclination than the radially inner hole wall 17a, becoming a roughly vertical surface. This shape prevents blood clots from passing through while allowing air bubbles to escape easily. Forming the top plate opening 17 is also easier. It should be noted that the inclination of the radially inner hole wall 17a and the radially outer hole wall 17b can be the same, and the angle of inclination is not particularly limited. Alternatively, a structure in which at least one of the radially inner hole wall 17a and the radially outer hole wall 17b is not inclined can also be used.

[0046] In this embodiment, the outer edge of the upper surface 21 of the top plate portion 11 is chamfered. The recess formed in the central portion is also formed gently. The upper end of the hole wall of the top plate opening portion 17 is chamfered. Therefore, there are no sharp corners on the upper surface of the top plate portion 11, which can suppress the occurrence of hemolysis caused by corners.

[0047] The filter 10 in this embodiment is not particularly limited and can be formed by injection molding of polypropylene or polyethylene. Any mold can be used for molding, but by using a mold with multiple gates on the lower ring 12 side for injection molding, compared to using a mold with a gate at the center of the top plate portion 11, the injection pressure can be reduced. This, in particular, reduces the burrs generated on the ribs 13.

[0048] Even a filter that includes only a portion of the structure of the filter of this embodiment, including the rib 13, the intermediate ring 14, and the top plate portion 11, can reduce blood retention.

[0049] Figure 9 shows the infusion chamber according to the second embodiment. As shown in Figure 9, the infusion chamber according to the second embodiment has a chamber body 200 and a filter 100 housed therein. The chamber body 200 has a cylindrical portion 205, an upper cover 203 mounted on the upper part of the cylindrical portion 205, and a lower cover 206 mounted on the lower part. The upper cover 203 has a plurality of ports 231 for connecting hoses. The number and arrangement of the ports 231 provided on the upper cover 203 are not particularly limited. The ports 231 may also be provided on the side of the upper cover 203. The lower cover 206 is tapered downwards, and a hose 302 is connected to its lower end. The filter 100 is embedded in the lower cover 206. It should be noted that the structure of the chamber body 200 is not limited to this.

[0050] As shown in Figures 10 and 11, the filter 100 has a filter holding portion 101 and a mesh filter 102 held by the filter holding portion 101. The mesh filter 102 is formed as a cylinder surrounding the filter holding portion 101, and the inner surface of the mesh filter 102 is in close contact with the outer surface of the filter holding portion 101 and fixed to the outer surface of the filter holding portion 101. Compared with the case where the mesh filter 102 is arranged inside the filter holding portion 101, by arranging the mesh filter 102 on the outer surface of the filter holding portion 101, it becomes much easier to fix it in close contact.

[0051] As shown in Figures 11 to 14, the filter holding part 101 includes a top plate part 111, a lower ring 113, and a support column 112 connecting the top plate part 111 and the lower ring 113. In this embodiment, two support columns 112 are provided at positions opposite each other across the center of the filter holding part 101. Therefore, the positions of the top plate part 111 and the lower ring 113 can be firmly fixed, and the shape of the filter 100 can be stabilized. Since a large opening can be ensured on the side of the filter holding part 101, retention is less likely to occur. However, there may be one support column 112 or three or more support columns.

[0052] The support column 112 does not protrude radially outward relative to the top plate portion 111 and the lower ring 113, and the outer surfaces of the top plate portion 111, the support column 112, and the lower ring 113 are the same surface. Therefore, by winding the mesh filter 102 around the outer side of the filter holding portion 101, and by making the inner surface of the mesh filter 102 closely adhere to the outer surfaces of the top plate portion 111, the support column 112, and the lower ring 113 and fixing it to the outer surfaces of the top plate portion 111, the support column 112, and the lower ring 113, the filter 100 can be easily formed.

[0053] The upper end of the mesh filter 102 is fixed to the side of the top plate 111, and the lower end is fixed to the side of the lower ring 113. The mesh filter 102 is supported by the support column 112 in the vertical direction. Therefore, the mesh filter 102 is not easily deformed, allowing blood to pass through stably. The length of the support column 112 can be appropriately set according to the required blood flow rate, but in the case of a typical blood circuit filter, from the viewpoint of ensuring the opening, the length of the support column 112 is preferably about 20 mm. From the viewpoint of ensuring strength, the width of the support column is preferably about 2.5 mm.

[0054] The mesh filter 102 can be fixed to the filter holder 101 by welding or bonding. In the case of welding, the mesh filter 102 can be welded by pressing the clamp from the outside while it is already wound around the filter holder 101. In the case of fixing by welding, since the structure in which the molten part of the filter holder 101 is wrapped around the mesh filter 102 is formed, the fixing method can be easily determined.

[0055] In this embodiment, the mesh filter 102 is fixed to the outer surface of the top plate portion 111. Therefore, it is not necessary to provide a recess or the like for receiving the mesh filter 102 on the lower surface of the top plate portion 111, and the top plate portion 111 is formed into a thick plate shape, with the lower surface being highest at the outer edge. Therefore, there is no space above the upper end of the mesh filter 102 through which blood can pass, making it difficult for blood to stagnate. The outer diameter of the top plate portion 111 can be appropriately determined according to the size of the chamber and the required blood flow rate, but in the case of a filter for a typical blood circuit, the outer diameter of the top plate portion 111 is preferably about 12 mm. Moreover, from the viewpoint of easily fixing the mesh filter 102 to the outer surface, the axial thickness of the outer edge is preferably about 3 mm.

[0056] A top plate opening 116 is provided on the top plate portion 111. By providing the top plate opening 116 on the top plate portion 111, air bubbles can be easily discharged during pre-charging. In this embodiment, the top plate opening 116 is a groove-shaped portion extending circumferentially between the central portion 111a and the outer edge portion 111b. The central portion 111a and the outer edge portion 111b are connected together by spoke portions 111c provided at 90° intervals, and the top plate opening 116 is divided into four parts.

[0057] As shown in Figure 12, in this embodiment, the radial width D2 of the lower end of the top plate opening 116 is smaller than the radial width D1 of the upper end. The radial width D2 at the lower end is a width that prevents blood clots and the like from passing through. The specific value of D2 can be determined considering various conditions; for example, it can be set to about 0.3 mm. By making the radial width D1 of the upper end greater than D2, blood clots and the like can be prevented from passing through, and air bubbles can be easily discharged during pre-filling. The formation of the top plate opening 116 also becomes easier. D1 is not particularly limited; for example, it can be about 1 mm. However, D1 and D2 can also be made equal.

[0058] In this embodiment, the hole wall 116b on the outer edge 111b side of the top plate opening 116 is a vertical surface, and the hole wall 116a on the central part 111a side is an inclined surface that slopes towards the outer edge as it descends. Because the hole wall 116b on the outer edge side is a vertical surface, and its radial thickness is equal to that of the annular outer edge 111b on the outer side of the top plate opening 116, deformation is less likely to occur during molding, resulting in a smooth side surface of the top plate 111. Therefore, the mesh filter 102 can be easily welded to the side surface of the top plate 111. However, as long as the top plate opening 116 has a radial width that prevents blood clots or similar substances from passing through, the hole wall 116b on the outer edge 111b side can also be an inclined surface, or both the hole wall 116b on the outer edge 111b side and the hole wall 116a on the central part 111a side can be inclined surfaces.

[0059] In this embodiment, the top plate opening 116 is a groove divided into four parts circumferentially, but the number of divisions can be set arbitrarily. Alternatively, a plurality of radially extending grooves can be arranged radially.

[0060] In this embodiment, a lower surface protrusion 117 is formed on the lower surface of the top plate portion 111, protruding from the outer edge portion 111b toward the center of the top plate portion 111, and the protrusion height gradually increases. Air bubbles reaching the lower surface of the top plate portion 111 move along the lower surface protrusion 117 toward the top plate opening portion 116. Therefore, air bubbles can be more easily expelled during pre-filling. The protrusion height h1 of the lower surface protrusion 117 is not particularly limited, but from the viewpoint of effectively expelling air bubbles, the protrusion height h1 is preferably about 1.6 mm. However, the lower surface protrusion 117 can be provided as needed, or it can be omitted.

[0061] In this embodiment, a recess 111d is provided in the center of the upper surface of the top plate portion 111. The recess 111d is a trace of the gate during molding, but by providing a recess 111d on the upper surface in correspondence with the protrusion 117 on the lower surface, it is possible to suppress the thickness change of the central portion 111a and make molding easier.

[0062] In this embodiment, the outer edge of the upper surface of the top plate portion 111 is chamfered. Furthermore, the upper end of the hole wall of the top plate opening portion 116 is chamfered. The recess 111d is a shallow, dish-shaped depression. Therefore, there are no sharp corners on the upper surface of the top plate portion 111, which can suppress the occurrence of hemolysis caused by corners.

[0063] In this embodiment, the outer diameter of the top plate 111 is the same as the outer diameter of the lower ring 113, and the filter 100 is cylindrical with a constant outer diameter. In the case of a frustoconical filter where the lower diameter is larger than the upper diameter, the amount of blood passing through the mesh filter 102 increases towards the lower part, which may cause blood stagnation in the upper part of the filter. Since the filter 100 in this embodiment is cylindrical, the amount of blood passing through the mesh filter is approximately constant, making it less likely for blood to stagnate within the filter and inhibiting the occurrence of coagulation. If the shape of the chamber body 200 is the same, a frustoconical filter is less likely to experience stagnation outside the filter. However, from the viewpoint of suppressing the greater problem of coagulation within the filter, a cylindrical filter is preferable.

[0064] By making the outer diameter of the top plate portion 111 match the outer diameter of the lower ring 113, the rectangular mesh filter 102 can be wound onto the filter holding portion 101, thus also having the advantage of making it very easy to form the filter 100.

[0065] In this embodiment, a flange portion 114 with an outer diameter larger than that of the lower ring 113 is provided at the lower end of the lower ring 113. A notch 114a is provided at the flange portion 114 at a position corresponding to the support post 112. By providing the notch 114a, the filter holding portion 101 can be easily clamped and rotated using a clamp. If the filter holding portion 101 is rotated with one side of the rectangular mesh filter 102 positioned at the position of a support post 112 and the adjacent side abutting against the flange portion 114, the mesh filter 102 can be easily and neatly wound onto the filter holding portion 101.

[0066] In this embodiment, the flange portion 114 also functions as a mounting portion for mounting the filter 100 onto the chamber body 200. As shown in FIG9, the filter 100 can be easily mounted onto the chamber body 200 by fitting the flange portion 114 into the recess provided on the inner surface of the lower cover 206. However, fixing the filter 100 onto the chamber body 200 is not limited to this method.

[0067] The outer diameter of the flange portion 114 is not particularly limited, but from the viewpoint of facilitating the winding of the mesh filter 102 and easy installation onto the chamber body 200, it is preferable that the outer diameter of the flange portion 114 is about 10% to 20% larger than the outer diameter of the lower ring 113. The flange portion 114 can be provided at the upper end of the lower ring 113, but it is not necessary for it to be provided at the lower end of the lower ring 113. The flange portion 114 may also be omitted. It is also possible to provide a flange portion 114 without the notch 114a.

[0068] The mesh filter 102 can use a typical screen with a pore size of about 40μm to 100μm for removing foreign matter, but it is preferable to use a screen made of a relatively hydrophilic material such as polyester. A screen that has undergone a hydrophilic treatment can also be used. The filter holding part 101 only needs to be made of a material that can be tightly attached to the mesh filter 102. When fixing the polyester mesh filter by high-frequency welding, polypropylene, which is easy to weld, is preferable.

[0069] The drip chamber of this embodiment can be connected to either the arterial or venous side of the blood circuit.

[0070] -Industry availability-

[0071] The filter for drip chambers disclosed herein is less prone to stagnation and can be used in drip chambers of blood circuits, etc.

[0072] 10: Filter 11: Top plate 12: Lower ring 13: Ribs 13a: Peripheral part 13b: Inner circumference 14: Intermediate ring 15: Slit 16: Gap 17: Top plate opening 17a: Hole wall 17b: Hole wall 18: Inclined area 19: Space 21: Upper surface 22: Lower surface 100: Filter 101: Filter holding section 102: Mesh Filter 111: Top plate section 111a: Central Department 111b: Outer edge 111c: Spoke section 111d: concave part 112: Pillar 113: Lower ring 114: Flange portion 114a: Gap 116: Top plate opening 116a: Hole wall 116b: Hole wall 117:Protrusion on lower surface 200: Main body of the chamber 201:Tubular part 201a: Groove 203: Upper cover 205:Tubular part 206: Lower cover 231: Port 301: Hose 302: Hose

Claims

1. A filter for a drip chamber, characterized in that it comprises a top plate, a lower ring, a plurality of ribs, and an intermediate ring, wherein the plurality of ribs connect the top plate and the lower ring, a plurality of slits are formed between the plurality of ribs, and the intermediate ring connects the ribs to each other in the circumferential direction; each rib has an outer periphery and a triangular inner periphery, the angle between the direction of extension of the side of the inner periphery and the radial direction is greater than the angle between the direction of extension of the side of the outer periphery and the radial direction; the radial thickness of the intermediate ring is thinner than the radial thickness of the rib located at the formation position of the intermediate ring; the cross-sectional shape of the rib is a pentagon formed by the combination of the isosceles trapezoidal outer periphery and the triangular inner periphery; the intermediate ring has only the outer edge of the outer periphery and is connected to the outer periphery.

2. The filter for the drip chamber as described in claim 1, wherein the circumferential width of the aforementioned slit remains substantially constant in the aforementioned outer periphery, or decreases slightly as it moves toward the radially inward side, while the circumferential width of the aforementioned slit increases in the aforementioned inner periphery as it moves toward the radially inward side.

3. The filter for the drip chamber as described in claim 2, wherein the circumferential width of the slit is 0.1 mm to 0.5 mm on the outer circumferential surface and 0.1 mm to 2.0 mm on the inner circumferential surface.

4. The filter for the drip chamber as described in claim 1, wherein the length of the aforementioned slit divided by the aforementioned intermediate ring in the height direction is more than 20% of the height of the filter.

5. A filter for an infusion chamber as described in claim 1, wherein the width of the aforementioned slits is consistent.

6. A filter for an infusion chamber as described in claim 1, wherein the aforementioned plurality of ribs have the same shape.

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