3D needle assembly

Abstract

To provide a needle assembly of a new structure capable of preventing the air from remaining in an inner passage.SOLUTION: In a needle assembly 10, an inner needle 16 is inserted in a hollow outer needle 56 in a removable manner, and a cylindrical outer needle hub 58 is fitted to the proximal end side of the outer needle 56 to form an inner passage 54 penetrating the outer needle 56 and the outer needle hub 58 in a direction of a needle axis. A valve 76 for switching communication and disconnection of the inner passage 54 is disposed at the inner passage 54. An air-draining passage 92 for making the more distal end side of the inner passage 54 than the valve 76 communicate with the outer space is provided in communication with the inner passage 54 in the vicinity of the valve 76. A large diameter part 96 increased in diameter of its proximal end side is provided in a step shape on the inner surface of the peripheral wall of the inner passage 54. The inner needle 16 comprises a small diameter tip part 22 to be inserted into the outer needle 56 and a large diameter base part 24 larger in diameter than the small diameter tip part 22, the large diameter base part 24 of the inner needle 16 being inserted in the large diameter part 96 of the inner passage 54.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a needle assembly used for blood collection, infusion (including blood transfusion), and the like.

Background Art

[0002] Conventionally, needle assemblies used for dialysis, infusion, and the like have been known. For example, in the indwelling needle disclosed in Japanese Patent Application Laid-Open No. 2015-136524 (Patent Document 1), a needle (inner needle) having a needle tip is inserted through a hollow catheter (outer needle), and an outer needle hub connected in a communicating state to the proximal end side of the catheter is provided. After the indwelling needle is punctured into a patient's blood vessel or the like with the catheter and the needle, the needle is removed, and the catheter is left in the blood vessel or the like. Then, dialysis or infusion is performed by connecting an external flow path such as a dialysis circuit or an infusion line to the catheter left in the blood vessel or the like.

[0003] Also, in the indwelling needle disclosed in Japanese Patent Application Laid-Open No. 2015-080707 (Patent Document 2), a rubber stopper portion as a valve body is housed in the outer needle hub (outer needle base), and the communication and blockage of the lumen of the outer needle base are switched by opening and closing a slit valve provided in the rubber stopper portion. That is, in a state where the inner needle is removed and the indwelling needle is left in the blood vessel, the slit valve of the rubber stopper portion is closed and the lumen of the outer needle base is blocked, so that blood leakage is restricted. On the other hand, when an external flow path is connected to the outer needle base, the slit valve of the rubber stopper portion opens, and the external flow path is connected to the blood vessel through the lumen of the indwelling needle.

Prior Art Documents

Patent Documents

[0005] Incidentally, in Patent Document 2, the lumen of the outer needle and the outer needle base needs to be filled with blood flowing in from the tip side of the rubber stopper, and it is necessary to prevent air from remaining in the lumen on the tip side of the rubber stopper when blood flows in. Therefore, in Patent Document 2, when blood flows into the lumen of the indwelling needle, air is discharged to the outside through a gap that serves as a ventilation channel formed between the outer needle base and the rubber stopper.

[0006] However, experimental confirmation by the inventors revealed that in some cases, air may not be sufficiently expelled and may remain in the lumen of the outer needle during puncture. Specifically, it was found that when the needle tip is pointed upward, air may not be sufficiently expelled and air bubbles may remain near the enlarged inner diameter portion of the outer needle assembly.

[0007] The problem to be solved by the present invention is to provide a needle assembly with a novel structure that can prevent the retention of air in the internal flow path. [Means for solving the problem]

[0008] The following describes preferred embodiments for understanding the present invention. However, each embodiment described below is illustrative and can be combined with others as appropriate. Furthermore, the multiple components described in each embodiment can be recognized and adopted as independently as possible, and can be combined with any component described in another embodiment as appropriate. Thus, the present invention is not limited to the embodiments described below, and various other embodiments can be realized.

[0009] The first embodiment is a needle assembly in which an inner needle is removably inserted into a hollow outer needle, a cylindrical outer needle hub is attached to the base end of the outer needle, an internal passage is formed that penetrates the outer needle and the outer needle hub in the direction of the needle axis, a valve body is disposed in the internal passage to switch between opening and closing the internal passage, and an air vent passage is provided near the valve body that communicates with the internal passage and connects the tip side of the internal passage to the outside space, the inner surface of the peripheral wall of the internal passage is provided with a stepped, enlarged diameter portion that is larger in diameter at the base end, and the inner needle has a small diameter tip portion that is inserted into the outer needle and a large diameter base portion that is larger in diameter than the small diameter tip portion, and the large diameter base portion of the inner needle is inserted into the enlarged diameter portion of the internal passage.

[0010] In a needle assembly with a structure according to this embodiment, even if the inner diameter of the inner surface of the peripheral wall of the internal flow path is larger on the proximal end side than the enlarged portion, the difference between the inner diameter of the internal flow path and the outer diameter of the inner needle is suppressed because the proximal end portion of the larger diameter inner needle is inserted into the enlarged portion of the internal flow path. Therefore, when the tip side of the internal flow path is filled with blood flowing in from the tip opening of the outer needle, air is more reliably pushed by the blood to the air vent passage near the valve, making it less likely for air to remain in the internal flow path.

[0011] The second embodiment is a needle assembly described in the first embodiment, wherein the outer needle hub has a needle joint portion to which the outer needle is fixed, a flow path connection portion that can be connected to an external flow path, and a flexible extension tube that connects the needle joint portion and the flow path connection portion so as to be displaceable relative to each other, and the large-diameter base portion of the inner needle is inserted into the extension tube.

[0012] When an extension tube is provided, for example, when the outer needle is inserted into a blood vessel and then placed in position, the extension tube can be deformed to displace the needle joint and the connection point relative to each other. Therefore, the connection point can be easily connected to an external flow path such as a dialysis circuit while maintaining the puncture state of the outer needle and suppressing the force acting on the puncture site. On the other hand, it has been confirmed that when an extension tube is provided, an expanded diameter section is likely to form, and air is likely to remain in the internal flow path. With a needle assembly structured according to this embodiment, air is less likely to remain in the internal flow path even when an extension tube is provided.

[0013] Because the portion of the inner needle that is inserted into the extension tube has a large-diameter base, deformation of the extension tube can be effectively limited by the inner needle, for example, during puncture.

[0014] The third embodiment is a needle assembly described in the first or second embodiment, wherein the tip portion of the large-diameter base of the inner needle is a tapered portion that becomes larger in diameter toward the base end.

[0015] According to the needle assembly structured in this embodiment, the outer surface of the small-diameter tip and the outer surface of the large-diameter base are continuous without a stepped shape, which makes it less likely for the blood flow on the outer side of the inner needle to be disturbed, thereby suppressing the entrapment of air due to turbulence.

[0016] The fourth aspect is a needle assembly described in any one of the first to third aspects, wherein the tip of the large-diameter base of the inner needle is located on the tip side of the enlarged diameter portion of the internal flow path.

[0017] According to the needle assembly structured in this embodiment, the large-diameter base of the inner needle can be inserted along the entire length of the internal channel from the enlarged diameter section toward the base end, thereby preventing the difference between the internal diameter of the internal channel and the external diameter of the inner needle from becoming excessively large toward the base end beyond the enlarged diameter section. Therefore, residual air caused by changes in the internal diameter of the internal channel is suppressed.

[0018] The fifth embodiment is a needle assembly described in any one of the first to fourth embodiments, wherein the base end portion of the outer needle is an expanded large-diameter portion that increases in diameter toward the base end, and the large-diameter base portion of the inner needle is inserted into the inner circumference of the expanded large-diameter portion.

[0019] In a needle assembly with a structure according to this embodiment, the large-diameter base of the inner needle is inserted into the inner circumference of the expanded large-diameter portion which is the base end of the outer needle. This reduces the difference between the inner diameter of the internal flow path in the expanded large-diameter portion and the outer diameter of the inner needle, thereby preventing air from remaining in the internal flow path.

[0020] A sixth aspect is a needle assembly in which an inner needle is removably inserted into a hollow outer needle, a cylindrical outer needle hub is attached to the base end of the outer needle, an internal passage is formed that penetrates the outer needle and the outer needle hub in the direction of the needle axis, a valve body is provided in the internal passage to switch between opening and closing the internal passage, and an air vent passage is provided near the valve body that communicates with the internal passage and connects the tip side of the internal passage to the external space, the internal passage having an enlarged passage section with a larger inner diameter than the tip side, the inner needle has a small-diameter tip section that is inserted into the outer needle and a large-diameter base section that has a larger diameter than the small-diameter tip section, and the large-diameter base section of the inner needle is inserted into the enlarged passage section of the internal passage.

[0021] In a needle assembly with a structure according to this embodiment, the large-diameter base of the inner needle is inserted into the widened portion of the internal flow path, reducing the volume of the space (flow path) formed between the inner needle and the widened portion. Therefore, when the tip of the internal flow path is filled with blood flowing in from the tip opening of the outer needle, air is pushed by the blood to the air vent passage near the valve, making it less likely for air to remain in the internal flow path.

[0022] A seventh aspect is that an inner needle is removably inserted into a hollow outer needle, a cylindrical outer needle hub is attached to the proximal end side of the outer needle, and an internal flow path is formed that penetrates the outer needle and the outer needle hub in the needle axis direction. A valve body for switching the communication and blocking of the internal flow path is arranged in the internal flow path, and an air vent passage that communicates the distal end side of the internal flow path with the external space is provided in the vicinity of the valve body and communicates with the internal flow path. The needle assembly is such that, on the proximal end side of the outer needle and on the distal end side of the valve body, the difference between the inner diameter dimension of the internal flow path and the outer diameter dimension of the inner needle is 1 mm or more and 1.5 mm or less.

[0023] According to the needle assembly having the structure according to this aspect, on the proximal end side of the outer needle and on the distal end side of the valve body, since the difference between the inner diameter dimension of the internal flow path and the outer diameter dimension of the inner needle is 1 mm or more, when the inner needle is inserted into the internal flow path, the inflow of blood or the like into the internal flow path can be effectively caused. Further, on the proximal end side of the outer needle and on the distal end side of the valve body, since the difference between the inner diameter dimension of the internal flow path and the outer diameter dimension of the inner needle is 1.5 mm or less, it is difficult for blood or the like flowing into the internal flow path from the distal end side to bypass to the proximal end side leaving air, and it is difficult for air to remain.

Effect of the Invention

[0024] According to the present invention, it is possible to prevent the remaining of air in the internal flow path of the needle assembly.

Brief Description of the Drawings

[0025] [Figure 1] Vertical sectional view showing a needle assembly as a first embodiment of the present invention

Mode for Carrying Out the Invention

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0027] Figure 1 shows a needle assembly 10 as a first embodiment of the present invention. The needle assembly 10 has a structure in which an inner needle assembly 12 and an outer needle assembly 14 are combined. In the following description, as a general rule, the axial direction refers to the left-right direction in Figure 1, which is the needle axis direction of the inner needle 16 and outer needle 56 described later, with the right end in Figure 1 being the tip and the left end in Figure 1 being the base.

[0028] The inner needle assembly 12 includes an inner needle 16. The inner needle 16 is a hollow metal needle, and its tip surface has an inclined blade surface 18, forming an acute-angled needle tip 20. In Figure 1, the blade surface 18 of the inner needle 16 is located on the upper side of the figure.

[0029] The inner needle 16 has an inner diameter that is substantially constant in the axial direction, and an outer diameter that is larger at the base end in the axial direction than at the tip end. It comprises a small-diameter tip portion 22, which is the tip portion with a smaller outer diameter, and a large-diameter base portion 24, which is the base portion with a larger outer diameter. In this embodiment, the large-diameter base portion 24 has a tapered portion 26 at the tip end that increases in diameter towards the base end, and a cylindrical portion 28 that extends from the tapered portion 26 towards the base end with a substantially constant outer diameter.

[0030] The inclination angle θ of the generatrix of the tapered portion 26 with respect to the axial direction is preferably 1° ≤ θ ≤ 10°. The outer diameter dimension φ1 of the large diameter base portion 24 in the cylindrical portion 28 is preferably 1.5 times or more the outer diameter dimension φ2 of the small diameter tip portion 22, and more preferably 2 times or more. The outer diameter dimension φ1 of the large diameter base portion 24 in the cylindrical portion 28 is preferably within the range of 2.35 mm ≤ φ1 ≤ 2.85 mm, and the outer diameter dimension φ2 of the small diameter tip portion 22 is preferably within the range of 1.03 mm ≤ φ2 ≤ 1.51 mm. Preferably, for example, the outer diameter dimension φ1 of the large diameter base portion 24 in the cylindrical portion 28 is 2.6 mm, and the outer diameter dimension φ2 of the small diameter tip portion 22 is 1.25 mm. Note that the outer diameter dimension φ1 of the large diameter base portion 24 may change in the axial direction on the base end side of the tapered portion 26.

[0031] An inner needle hub 30 is provided on the base end side of the inner needle 16. The inner needle hub 30 has a base portion 32 to which the base end portion of the inner needle 16 is fixed in an inserted state, and a protector housing portion 34 is provided on the tip side of the base portion 32, and a connecting portion 36 is provided on the base end side of the base portion 32.

[0032] The protector housing section 34 is cylindrical. A regulating cylinder section 38, which is roughly cylindrical and has a larger diameter than the protector housing section 34, is provided at the tip of the protector housing section 34. The outer surface of the protector housing section 34 may be provided with anti-slip features such as protrusions, recesses, or textures.

[0033] The connecting section 36 is cylindrical, and a filter cap 40 is removably inserted and attached to it. The filter cap 40 has a roughly stepped cylindrical shape with a step in the middle section in the axial direction. The tip of the filter cap 40 is equipped with a filter that allows the passage of gas but prevents the passage of liquid, so that the backflow of blood through the inner needle 16 does not leak out to the outside. If the inner needle hub 30 and the filter cap 40 are transparent or semi-transparent, the puncture into the blood vessel can be easily confirmed by the backflow of blood (flashback).

[0034] A protector housing 42 is positioned on the inner circumference of the protector housing 34. The protector housing 42 comprises a cylindrical housing portion 44 and a cover 46 that closes the opening at the tip end of the housing portion 44. The cover 46 has a plate-shaped portion at the tip end and a plate-shaped portion at the base end that are separated in the axial direction, and a needle tip protector 48 is positioned between these plate-shaped portions.

[0035] The needle tip protector 48 is composed of a shielding member 50 and a fixing member 52 housed in a protector housing 42. The shielding member 50 and the fixing member 52 are positioned apart from each other in a direction perpendicular to the axis, with the inner needle 16 in between. One of the shielding member 50 and the fixing member 52 is a magnet, and the other is a magnet or a ferromagnetic material, and a magnetic attractive force acts between the shielding member 50 and the fixing member 52. In this embodiment, the shielding member 50 is made of a ferromagnetic material such as iron, and the fixing member 52 is a permanent magnet. The fixing member 52 is fixed to the tip of the housing cylinder portion 44. The shielding member 50 is displaceable in the direction approaching the fixing member 52, and when the inner needle 16 is inserted between the shielding member 50 and the fixing member 52, the movement of the shielding member 50 toward the fixing member 52 is prevented by the inner needle 16. Then, as the inner needle 16 is pulled out toward the base end and displaced relative to the shielding member 50 toward the base end, the movement of the shielding member 50 toward the fixing member 52 due to magnetic attraction is permitted, and the shielding member 50 moves to a position where it covers the needle tip 20 of the inner needle 16, and the movement of the inner needle 16 toward the tip is prevented by the shielding member 50.

[0036] The inner needle 16 is inserted into the outer needle assembly 14 in a manner that allows it to be removed. The outer needle assembly 14 is a cylindrical body with an internal flow path 54 that penetrates in the axial direction, and has a hollow outer needle 56 and an outer needle hub 58 that is connected in communication with the base end of the outer needle 56.

[0037] The outer needle 56 is a hollow, small-diameter tube made of synthetic resin or the like. The outer surface of the outer needle 56 has a tapered shape, with the diameter gradually decreasing towards the tip. The base end portion of the outer needle 56 is provided with an expanding large-diameter section 60, which expands towards the base end to become larger in diameter. The base end portion of the outer needle 56 is larger in diameter than the tip end portion because it is provided with the expanding large-diameter section 60. In this embodiment, the expanding large-diameter section 60 of the outer needle 56 is thicker than the tip end portion. The lumen of the outer needle 56 is larger in diameter at the base end portion where the circumferential wall is formed by the expanding large-diameter section 60. The inner circumferential surface of the outer needle 56 is composed of a smoothly continuous curved surface without any steps or corners being formed in the axial and circumferential directions.

[0038] The outer needle hub 58 is cylindrical overall, and has a structure in which the needle joint portion 68 and the flow path connection portion 70 are connected by an extension tube 72.

[0039] The needle joint portion 68 is made of a hard synthetic resin. The needle joint portion 68 is tapered cylindrical in shape, becoming smaller in diameter towards the tip. The expanded large-diameter portion 60 of the outer needle 56 is inserted into the inner circumference of the needle joint portion 68.

[0040] The flow path connection section 70 is cylindrical overall, and an external flow path (not shown) can be connected to its base end. In this embodiment, the flow path connection section 70 has a structure in which a valve body 76 and a plunger 78 are housed in a cylindrical valve housing 74.

[0041] The valve housing 74 is constructed by inserting the tip of a cylindrical plunger guide 82 into the base end of a cylindrical cover member 80, thereby connecting the cover member 80 and the plunger guide 82 in the axial direction.

[0042] The tube connecting member 84 is attached to the cover member 80 in an inserted state. The tube connecting member 84 is fixed by overlapping it with the inner circumferential surface of the tip portion of the cover member 80. The base end of the tube connecting member 84 is positioned opposite the cover member 80 at a distance toward the inner circumference.

[0043] The plunger guide 82 is cylindrical with its base end extending axially, and a male thread is provided at the base end that protrudes outward.

[0044] The valve body 76 is generally disc-shaped and is made of an elastic material such as resin elastomer or rubber. The valve body 76 has radial notches 88 formed in the central part of its disc shape, and the notches 88 are opened and closed by the elastic deformation of the central part. The outer circumference of the valve body 76 is axially sandwiched between the tip of the plunger guide 82 and a cylindrical valve support member 90 arranged on the inner circumference of the cover member 80. As a result, the valve body 76 is supported by the valve housing 74, and the portion of the internal flow path 54 formed by the lumen of the valve housing 74 is blocked by the valve body 76.

[0045] The valve support member 90 is positioned slightly inward relative to the cover member 80, and a gap is provided between the valve support member 90 and the cover member 80 in the radial direction. The air vent passage 92, which connects the internal flow path 54 of the outer needle assembly 14 to the external space, is formed including the gap between the valve support member 90 and the cover member 80. One end of the air vent passage 92 is connected to the internal flow path 54 of the outer needle assembly 14 through the gap between the tube connecting member 84 and the valve support member 90, and the other end is connected to the external space through the gap between the cover member 80 and the plunger guide 82. As a result, the part of the internal flow path 54 of the outer needle assembly 14 that is ahead of the valve body 76 is connected to the external space through the air vent passage 92. The opening of the air vent passage 92 to the internal flow path 54 is set to be ahead of the valve body 76 and close to the valve body 76, so that the air vent passage 92 is connected to the internal flow path 54 in the vicinity of the valve body 76. Furthermore, it is desirable that the air vent passage 92 has a small cross-sectional area to allow gas flow and restrict liquid flow. In addition, the air vent passage 92 in this embodiment has a larger cross-sectional area in the middle section, so that if blood enters the air vent passage 92, the blood will be stored in the middle section and it will be difficult for the blood to leak from the air vent passage 92 into the outside space. In this embodiment, the air vent passage 92 is connected to the outside space midway along the axial direction of the outer needle hub 58, but for example, the air vent passage may be provided so that the tip side of the valve body 76 in the internal flow path 54 is connected to the base end side of the valve body 76, in which case the air vent passage is connected to the outside space at the base end opening of the internal flow path 54.

[0046] A ventilation filter 94 is provided in the air vent passage 92. The ventilation filter 94 is a filter that allows the passage of gas but restricts the passage of liquids such as blood, and is cylindrical or annular in shape. The ventilation filter 94 is positioned radially between the tube connecting member 84 and the valve support member 90 and the cover member 80, and is held in a compressed state in the radial direction. Because the ventilation filter 94 is positioned on the air vent passage 92, when the internal flow path 54 of the outer needle assembly 14 is filled with blood, the ingress of blood into the air vent passage 92 is suppressed by the ventilation filter 94, and leakage of blood to the outside through the air vent passage 92 is prevented.

[0047] The plunger 78 is cylindrical and inserted into the inner circumference of the plunger guide 82. The base end of the plunger 78 has a substantially constant outer diameter, while the outer surface of the tip end has a tapered shape, becoming smaller in diameter towards the tip.

[0048] The extension tube 72 connecting the needle joint 68 and the flow path connection 70 is a flexible soft tube made of resin elastomer or rubber, which is capable of bending and deformation, and also allows for changes in its cross-sectional shape. The provision of the extension tube 72 makes it easier to connect an external flow path, such as an infusion line, to the outer needle hub 58 while the needle joint 68 is fixed to the skin. The tip of the extension tube 72 is fixed to the needle joint 68, and the base end is fixed to the flow path connection 70. As a result, the needle joint 68 and the flow path connection 70 are connected by the extension tube 72, and the lumen of the flow path connection 70 is in communication with the lumen of the extension tube 72. The extension tube 72 is capable of deformation such as bending and crushing in the intermediate portion located away from both the needle joint 68 and the flow path connection 70.

[0049] The expanded diameter portion 60 of the outer needle 56 is inserted into the tip portion of the extension tube 72 and fixed to the inner circumferential surface of the tip portion of the extension tube 72. As a result, the expanded diameter portion 60 of the outer needle 56 is fixed to the needle joint portion 68 via the extension tube 72, and the outer needle hub 58, including the needle joint portion 68 and the extension tube 72, is connected to the proximal end of the outer needle 56, and the lumen of the outer needle 56 and the lumen of the outer needle hub 58 are in communication with each other.

[0050] The expanded large-diameter portion 60 of the outer needle 56 is inserted into the tip portion of the extension tube 72, so that a stepped expanded diameter portion 96 is formed on the inner circumference side of the extension tube 72 by the base end of the outer needle 56. In the portion of the internal flow path 54 of the outer needle assembly 14 that is composed of the extension tube 72, the flow path expansion portion 98 is larger in diameter on the base end side than on the tip end side than on the expanded diameter portion 96. The difference between the inner diameter dimension φ3 of the flow path expansion portion 98 in the internal flow path 54 and the inner diameter dimension φ4 on the tip side of the expanded diameter portion 96 in the internal flow path 54 (the inner diameter dimension of the base end opening of the expanded large-diameter portion 60) is preferably 2 mm or less, for example, 1.35 mm. The difference between the outer diameter dimension φ1 of the large-diameter base portion 24 and the outer diameter dimension φ2 of the small-diameter tip portion 22 of the inner needle 16 is preferably approximately the same as the difference between the inner diameter dimension φ3 of the flow path expansion portion 98 and the inner diameter dimension φ4 of the base end opening of the expanded large-diameter portion 60.

[0051] An inner needle assembly 12, equipped with an inner needle 16, and an outer needle assembly 14, equipped with an outer needle 56, are connected by a connector cap 100. The connector cap 100 has a bottom wall portion 102 that extends perpendicular to the axis. The bottom wall portion 102 is an annular plate shape, and a tubular projection 104 protruding toward the tip is integrally formed at its inner circumferential end. At the outer circumferential end of the bottom wall portion 102, a circumferential wall portion 106 extending toward the tip and a pair of elastic pieces 108, 108 extending toward the base end are integrally formed.

[0052] The inner surface of the cylindrical circumferential wall portion 106 is provided with an internal thread. The base end portion of the plunger guide 82, which constitutes the outer needle hub 58, is inserted into the inner circumference of the circumferential wall portion 106, and the plunger guide 82 and the circumferential wall portion 106 are screwed together, thereby attaching the connector cap 100 to the base end portion of the outer needle hub 58.

[0053] Each of the pair of elastic pieces 108, 108 is provided with a locking projection (not shown) that protrudes toward the inner circumference. The tip portion of the protector housing 42, inserted into the inner circumference of the pair of elastic pieces 108, 108, is axially locked with the locking projection. When the inner needle 16 is pulled out toward the base end, the protector housing 42 (needle tip protector 48) is held toward the outer needle assembly 14 and moves toward the needle tip 20 of the inner needle 16. Additionally, a crushed portion (not shown) of the inner needle 16 engages with the base bottom wall of the protector housing 42, and when the protector housing 42 is strongly pulled toward the base end, the engagement between the protector housing 42 and the locking projection is released, allowing the inner needle assembly 12, with the needle tip 20 of the inner needle 16 covered by the needle tip protector 48, to be separated from the outer needle assembly 14.

[0054] In the assembled state of the inner needle assembly 12 and the outer needle assembly 14, the restricting cylinder portion 38 of the inner needle hub 30 is fitted onto the connector cap 100. As a result, the deformation of the elastic pieces 108, 108 toward the outer circumference is restricted by the restricting cylinder portion 38, and the connection between the connector cap 100 and the protector housing 42 by the locking projections provided on the pair of elastic pieces 108, 108 is stably maintained.

[0055] The inner needle 16 is inserted from the proximal end into the internal flow path 54 of the outer needle assembly 14, which is composed of the lumen of the outer needle 56 and the lumen of the outer needle hub 58. The inner needle 16 pushes open the notch 88 of the valve body 76, which is located in the internal flow path 54 of the outer needle assembly 14, and penetrates the notch 88, and is inserted into the extension tube 72 and the outer needle 56 on the tip side of the valve body 76.

[0056] The inner needle 16 has a small-diameter tip portion 22 which is the tip portion, inserted into the outer needle 56 at a tip-side to the enlarged diameter portion 96 in the internal flow path 54 of the outer needle assembly 14, and a large-diameter base portion 24 which is the base portion, inserted into the enlarged diameter portion 96. In this embodiment, the tapered portion 26 of the large-diameter base portion 24 is inserted into the enlarged diameter portion 96 of the internal flow path 54, and the cylindrical portion 28 of the large-diameter base portion 24 is inserted into the flow path enlargement portion 98 at the base end side of the enlarged diameter portion 96 in the internal flow path 54. The flow path enlargement portion 98 in the internal flow path 54 of the outer needle assembly 14 is formed by the lumen of the extension tube 72, and the large-diameter base portion 24 of the inner needle 16 is inserted into the extension tube 72. The tip of the tapered portion 26 of the large-diameter base 24 is inserted into the outer needle 56, the tip of the large-diameter base 24 is located on the tip side of the enlarged diameter portion 96, and the base end portion of the tapered portion 26 protrudes on the base side of the outer needle 56, so that the enlarged diameter portion 96 is located in the middle of the tapered portion 26 in the axial direction.

[0057] In this manner, the small-diameter tip portion 22 of the inner needle 16 is inserted into the small-diameter portion of the internal flow path 54 of the outer needle assembly 14 that is closer to the tip than the enlarged portion 96, and the large-diameter base portion 24 of the inner needle 16 is inserted into the enlarged portion 96 and the flow path expansion portion 98 of the internal flow path 54. As a result, the amount of change in the distance between the outer diameter of the inner needle 16 and the inner surface of the peripheral wall of the internal flow path 54 in the axial direction is reduced.

[0058] In other words, if the internal flow path 54 of the outer needle assembly 14 is a flow path expansion section 98 with a larger diameter at the base end than the enlarged diameter section 96, and the outer diameter of the inner needle 16 is kept constant, the distance between the inner surface of the circumferential wall of the internal flow path 54 and the outer surface of the inner needle 16 will increase in the flow path expansion section 98. In contrast, in this embodiment, the insertion portion of the inner needle 16 into the flow path expansion section 98 of the internal flow path 54 is a large-diameter base section 24 with a larger outer diameter than the small-diameter tip section 22. As a result, the outer diameter of the inner needle 16 changes in accordance with the change in the internal diameter of the internal flow path 54 in the enlarged diameter section 96, and the amount of change in the distance between the inner surface of the circumferential wall of the internal flow path 54 and the outer surface of the inner needle 16 is reduced.

[0059] Furthermore, by minimizing the change in distance between the inner surface of the circumferential channel 54 of the outer needle assembly 14 and the outer surface of the inner needle 16, when blood flows from the tip side into the air-filled internal channel 54 after puncturing a blood vessel, air is less likely to remain.

[0060] In other words, the needle assembly 10 is inserted into a blood vessel in the patient's arm or leg (not shown) with the inner needle 16 inserted through the outer needle 56. When the inner needle 16 and outer needle 56 are inserted into the patient's blood vessel, blood enters between the inner needle 16 and the outer needle 56, and flows into the internal flow channel 54 of the outer needle assembly 14 from the tip side. The blood that has flowed into the internal flow channel 54 flows towards the proximal end, pushing the air inside the internal flow channel 54 towards the proximal end due to the action of gravity and blood pressure. The air pushed towards the proximal end by the blood is discharged to the outside through the air vent passage 92 that opens on the tip side of the valve body 76, thus allowing the blood to flow towards the proximal end.

[0061] Since blood flows between the outer surface of the inner needle 16 and the inner surface of the inner channel 54 of the outer needle assembly 14, if the separation distance between the outer surface of the inner needle 16 and the inner surface of the inner channel 54 does not change significantly, the blood will fill the inner channel 54 from the tip to the proximal end, pushing the air away. However, if the separation distance between the outer surface of the inner needle 16 and the inner surface of the inner channel 54 of the outer needle assembly 14 becomes large at the enlarged diameter portion 96, there is a risk that the blood will flow around to the proximal end at the enlarged diameter portion 96, leaving air behind, and air is more likely to remain in the inner channel 54. In particular, when the outer needle 56 is inserted into a blood vessel, if the tip of the outer needle assembly 14 is positioned above the proximal end, air is more likely to remain due to the blood flowing around.

[0062] Therefore, in this embodiment, the portion of the inner needle 16 that is inserted into the enlarged diameter portion 96 and the flow path expansion portion 98 of the internal flow path 54 is a large-diameter base portion 24 whose outer diameter is larger than that of the small-diameter tip portion 22. This prevents the separation distance between the outer circumferential surface of the inner needle 16 and the inner surface of the peripheral wall of the internal flow path 54 of the outer needle assembly 14 from becoming excessively large in the enlarged diameter portion 96 and the flow path expansion portion 98 of the internal flow path 54. As a result, when blood flows from the tip side into the enlarged diameter portion 96 and the flow path expansion portion 98, it is possible to prevent the blood from flowing around to the base end side while leaving air behind, thereby preventing the retention of air in the enlarged diameter portion 96 and the flow path expansion portion 98.

[0063] The difference between the inner diameter φ3 of the flow path expansion section 98 in the internal flow path 54 and the outer diameter φ1 of the large-diameter base 24, which is the portion of the inner needle 16 that is inserted into the flow path expansion section 98, is set to 1 mm or more. This allows for effective blood flow into the internal flow path 54 into which the inner needle 16 is inserted. Furthermore, the difference between the inner diameter φ3 of the flow path expansion section 98 in the internal flow path 54 and the outer diameter φ1 of the large-diameter base 24, which is the portion of the inner needle 16 that is inserted into the flow path expansion section 98, is set to 1.5 mm or less. This makes it difficult for blood flowing into the internal flow path 54 into which the inner needle 16 is inserted from the tip side to flow around to the base side while leaving air behind, and the air is pushed towards the air vent passage 92 side by the blood, thus making it difficult for air to remain. In this embodiment, the flow path expansion section 98 in the internal flow path 54 is located on the base side of the outer needle 56 and on the tip side of the valve body 76. Furthermore, in this embodiment, the internal flow path 54 has a larger diameter in the region adjacent to the tip side of the valve body 76, and the large-diameter base 24 of the inner needle 16 has a smaller diameter at the tip. It is desirable that the difference between the inner diameter of the internal flow path 54 and the outer diameter of the inner needle 16 be 1.5 mm or less in the large-diameter region of the internal flow path 54 and the small-diameter portion (tapered portion 26) of the large-diameter base 24, respectively. However, the above effects can be expected if the difference between the inner diameter of the internal flow path 54 and the outer diameter of the inner needle 16 is 1 mm or more and 1.5 mm or less in at least the portion where the peripheral wall of the internal flow path 54 is composed of the extension tube 72.

[0064] The tip of the large-diameter base 24 of the inner needle 16 is a tapered portion 26 that becomes larger in diameter towards the base end, so that the outer surface of the small-diameter tip 22 and the outer surface of the large-diameter base 24 are continuous without a step-like shape. As a result, the blood flow on the outer surface of the inner needle 16 is less disturbed at the connection between the small-diameter tip 22 and the large-diameter base 24, suppressing air entrapment and damage to blood cells due to turbulence.

[0065] The inner needle 16 has a tapered portion 26, which is the tip of the large-diameter base 24, inserted further forward than the enlarged portion 96 in the internal flow path 54 of the outer needle assembly 14. As a result, the large-diameter base 24 of the inner needle 16 is inserted along the entire length of the enlarged flow path portion 98 of the internal flow path 54, which has a larger flow path cross-sectional area. This prevents the difference between the inner diameter of the internal flow path 54 and the outer diameter of the inner needle 16 from becoming excessively large on the base end side of the enlarged portion 96, thereby effectively suppressing the retention of air in the internal flow path 54.

[0066] The tapered portion 26, which is the tip of the large-diameter base portion 24 of the inner needle 16, is inserted into the expanded large-diameter portion 60 that constitutes the base portion of the outer needle 56. As a result, even in the expanded large-diameter portion 60 of the outer needle 56, which is located on the tip side of the expanded diameter portion 96, the change in the radial distance between the inner surface of the peripheral wall of the internal flow path 54 and the outer surface of the inner needle 16 is suppressed, and the retention of air in the internal flow path 54 is suppressed.

[0067] In this embodiment, the portion of the inner needle 16 that is inserted into the extension tube 72 is a large-diameter base 24, and the distance between the inner circumferential surface of the extension tube 72 and the outer circumferential surface of the inner needle 16 is small. Therefore, even if a puncture resistance force acts on the outer needle 56 side during puncture, for example, the deformation of the extension tube 72 is limited by the inner needle 16, enabling stable puncture. In addition, although puncture is performed by holding the inner needle hub 30, even if puncture is performed by holding the outer needle hub 58, the amount of deformation of the extension tube 72 is limited, making puncture relatively easy.

[0068] Incidentally, after the inner needle 16 and outer needle 56 have been inserted into the patient's blood vessel, the inner needle 16 is withdrawn from the outer needle 56, and the outer needle assembly 14 is left in place with the outer needle 56 inserted into the patient's blood vessel. Then, the connector cap 100 is removed from the left-in outer needle assembly 14, and the external flow path, such as an infusion line or syringe, is connected to the flow path connection part 70 of the outer needle hub 58. When connecting the external flow path to the flow path connection part 70, the plunger 78 is pushed toward the tip and inserted into the notch 88 of the valve body 76, thereby releasing the blockage of the internal flow path 54 by the valve body 76, and the external flow path is opened to communicate with the patient's blood vessel through the internal flow path 54.

[0069] Because the external needle hub 58 is equipped with an extension tube 72, for example, when the external needle 56 is placed in a punctured blood vessel, the extension tube 72 can be deformed to cause relative displacement between the needle joint 68 and the flow path connection 70. Therefore, the flow path connection 70 can be easily connected to an external flow path such as a dialysis circuit while maintaining the puncture state of the external needle 56 and suppressing the force acting on the puncture site. In addition, the internal flow path 54 can be switched between open and closed by clamping the extension tube 72.

[0070] Although embodiments of the present invention have been described in detail above, the present invention is not limited by its specific description. For example, the inner diameter of the inner needle 16 may vary in the axial direction. That is, for example, the inner diameter of the large-diameter base portion 24, which has a larger outer diameter, may be larger than that of the small-diameter tip portion 22, which has a smaller outer diameter.

[0071] In the above embodiment, an example was shown in which the tip portion of the large-diameter base portion 24 of the inner needle 16 is a tapered portion 26. However, the small-diameter tip portion 22 and the large-diameter base portion 24 can also be connected by, for example, a step. Furthermore, the rate of change in the axial direction of the outer diameter dimension of the tapered portion 26 may be substantially constant or may vary. Also, for example, if a plurality of enlarged diameter portions 96 are provided at multiple locations in the axial direction, and the inner diameter dimension of the internal flow path 54 increases in multiple stages toward the base end, the outer diameter dimension of the inner needle 16 may also increase in multiple stages toward the base end.

[0072] The large-diameter base portion 24 does not necessarily have to extend to the base end of the inner needle 16. For example, if the internal flow path 54 is provided with a flow path expansion portion 98 so that it partially widens in the axial direction, the large-diameter base portion 24 may be provided in a portion of the axial direction that does not reach the base end into which the inner needle 16 is inserted. More specifically, for example, in the above embodiment, the portion of the inner needle 16 that is inserted into the extension tube 72 may be the large-diameter base portion 24, and the portion on the base end side of the portion inserted into the extension tube 72 may be smaller in diameter than the large-diameter base portion 24 and not be the large-diameter base portion 24.

[0073] The large-diameter base 24 of the inner needle 16 is preferably inserted into the smaller diameter portion of the internal flow path 54 on the tip side of the enlarged diameter portion 96, as in the above embodiment, with a tapered tip, but is not limited to this configuration. For example, the large-diameter base 24 may not be inserted into the smaller diameter portion of the internal flow path 54, but may be slightly separated from the enlarged diameter portion 96 towards the base end.

[0074] In the invention according to the seventh aspect, the enlarged diameter portion 96 and the flow path expansion portion 98 of the internal flow path 54 are not essential, nor is the large-diameter base portion 24 of the inner needle 16 essential. Specifically, for example, by forming a recess that opens to the inner circumferential surface and the tip surface at the tip portion of the outer needle hub, and inserting the base portion of the outer needle into the recess, the inner circumferential surface of the outer needle hub and the inner circumferential surface of the outer needle can be provided with substantially the same diameter without forming a stepped enlarged diameter portion.

[0075] In the above embodiment, an example was shown in which the channel expansion portion 98 of the internal channel 54 is formed by the lumen of a flexible extension tube 72, but the channel expansion portion 98 can also be provided in, for example, a rigid needle hub. The extension tube 72 is not essential, and the present invention can be applied even to needle hubs that do not have an extension tube 72. [Explanation of symbols]

[0076] 10 needle assembly 12 Inner needle assembly 14 Outer needle assembly 16 Inner Hand 18 Blade surface 20 needle tip 22 Small diameter tip 24 Large diameter base 26 Tapered section 28 Cylindrical part 30 Inner needle hub 32 Base 34 Protector housing 36 Connecting part 38 Regulating cylinder section 40 filter caps 42 Protector Housing 44. Enclosure section 46 Lid 48 Needle tip protector 50 Shielding member 52 Fixing member 54 Internal flow path 56 Outer needle 58 Outer needle hub 60 Expanded diameter section 68 Needle joint 70 Flow channel connection section 72 Extension tube 74 Valve Housing 76 Valve body 78 Pusher 80 Cover component 82 Pusher Guide 84 Tube connecting member 88 cuts 90 Valve support member 92 Air vent passage 94 Ventilation filter 96 Expanded diameter part 98 Flow channel widening section 100 Connector Caps 102 Bottom wall section 104 Tubular process 106 Circumferential wall 108 Elastic piece

Claims

1. The inner needle is removably inserted into the hollow outer needle. A cylindrical outer needle hub is attached to the base end of the outer needle, and an internal flow path is formed that penetrates the outer needle and the outer needle hub in the direction of the needle axis, The internal flow path is equipped with a valve that switches between opening and closing the internal flow path. A needle assembly having an air vent passage that connects the tip of the internal flow path to the external space, and which is provided in the vicinity of the valve body and communicates with the internal flow path, The inner surface of the peripheral wall of the aforementioned internal flow channel is provided with a stepped, enlarged diameter section at the base end, The inner needle has a small-diameter tip portion that is inserted into the outer needle, and a large-diameter base portion that is larger in diameter than the small-diameter tip portion. A needle assembly in which the large-diameter base of the internal needle is inserted into the enlarged portion of the internal flow path.

2. The outer needle hub has a needle joint portion fixed to the outer needle, a flow path connection portion that can be connected to an external flow path, and a flexible extension tube that connects the needle joint portion and the flow path connection portion so that they can be displaced relative to each other. The needle assembly according to claim 1, wherein the large-diameter base of the inner needle is inserted into the extension tube.

3. The needle assembly according to claim 1 or 2, wherein the tip portion of the large-diameter base of the inner needle is a tapered portion that becomes larger in diameter toward the base end.

4. The needle assembly according to claim 1 or 2, wherein the tip of the large-diameter base of the inner needle is located on the tip side of the enlarged diameter portion of the internal flow path.

5. The needle assembly according to claim 1 or 2, wherein the base end portion of the outer needle is an expanding tapered portion that becomes larger in diameter toward the base end, and the large-diameter base portion of the inner needle is inserted into the inner circumference of the expanding tapered portion.

6. The inner needle is removably inserted into the hollow outer needle. A cylindrical outer needle hub is attached to the base end of the outer needle, and an internal flow path is formed that penetrates the outer needle and the outer needle hub in the direction of the needle axis, The internal flow path is equipped with a valve that switches between opening and closing the internal flow path. A needle assembly having an air vent passage that connects the tip of the internal flow path to the external space, and which is provided in the vicinity of the valve body and communicates with the internal flow path, The aforementioned internal flow path includes a flow path enlargement section whose inner diameter is larger than that of the tip end. The inner needle has a small-diameter tip portion that is inserted into the outer needle, and a large-diameter base portion that is larger in diameter than the small-diameter tip portion. A needle assembly in which the large-diameter base of the internal needle is inserted into the enlarged portion of the internal flow path.

7. The needle assembly according to claim 1 or 6, wherein, in the internal flow path, on the proximal end side of the outer needle and on the tip side of the valve body, the difference between the inner diameter of the internal flow path and the outer diameter of the inner needle is 1 mm or more and 1.5 mm or less.

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