External needle assembly three-dimensional

Abstract

Provided is an outer needle assembly having a novel structure capable of preventing air from remaining therein.　The outer needle assembly 10 comprises a hollow outer needle 48 wherethrough an inner needle 16 passes, and a flow path forming member 50 connected to the outer needle 48, a valve body 64 being provided to the interior of the flow path forming member 50, such that a first inner space 78, which is more to the forward end side than the valve body 64, has a long dimension in comparison to a second inner space 79, which is on the base end side from the valve body 64. In the outer needle assembly 10, an air passage route 80, whereby the air in the first inner space 78 is released to the exterior, communicates with the first inner space 78 in the vicinity of the valve body 64, while the first inner space 78 comprises: a puncture section 56 formed in a blood vessel puncturing portion of the outer needle 48; a tapered section 57 formed more to the base end side than the puncture section 56, whereof the inner diameter dimension increases toward the base end side; and a small-diameter section 89 formed more to the base end side than the tapered section 57, whereof the inner diameter dimension is identical or small in comparison to that at the base end of the tapered section 57.

Description

[Technical Field]

[0001] The present invention relates to an outer needle assembly in which a flow path forming member is connected to the base end side of an outer needle, and in particular to an outer needle assembly provided with an air passage that allows air to be discharged from the inner cavity of the flow path forming member to the outside, and a valve body that connects / blocks the inner cavity of the flow path forming member. [Background technology]

[0002] Outer needle assemblies used for dialysis, infusion, etc. have been known for some time. For example, like the indwelling needle disclosed in Japanese Patent Laid-Open Publication No. 2015-080707 (Patent Document 1), an outer needle assembly has a hollow outer needle and a flow path-forming member such as an outer needle base connected in communication with the base end of the outer needle. The outer needle assembly is placed in the blood vessel or the like by inserting the outer needle together with the inner needle into a patient's blood vessel or the like, and then removing the inner needle. Dialysis or infusion is then performed by connecting an external flow path such as a dialysis circuit or an infusion line to the outer needle assembly placed in the blood vessel or the like.

[0003] Furthermore, the indwelling needle of Patent Document 1 has a rubber stopper portion housed in the outer needle base as a valve body, and the opening and closing of a slit valve provided in the rubber stopper portion switches between communication and blocking of the lumen of the outer needle base. That is, when the inner needle is removed and the indwelling needle is left in a blood vessel, the slit valve in the rubber stopper portion closes to block the lumen of the outer needle base, thereby restricting blood leakage. On the other hand, when an external flow path is connected to the outer needle base, the slit valve in the rubber stopper portion opens, and the external flow path is connected to the blood vessel via the lumen of the indwelling needle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-080707 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, before connecting an external flow path to an outer needle assembly that has been placed in a blood vessel, it is necessary to fill the lumen with a liquid such as blood to expel air and prevent air from entering the blood vessel. Therefore, in Patent Document 1, when blood flows into the lumen of the indwelling needle (outer needle assembly), air is discharged to the outside through a gap that serves as an air passage formed between the outer needle base and the rubber stopper portion.

[0006] However, the inventors have confirmed through experiments that if the outer needle assembly is tilted so that the needle tip points diagonally upward when performing the puncture, air may not be sufficiently expelled and may remain in the inner cavity of the outer needle assembly.

[0007] An object of the present invention is to provide an outer needle assembly with a novel structure that can prevent air from remaining inside. [Means for solving the problem]

[0008] In order to prevent air from remaining in the lumen of the outer needle assembly, the inventor first attempted to change the shape, size, number, arrangement, etc. of the air passage, but was unable to achieve sufficient results.

[0009] Next, the inventors conducted detailed experiments to observe the flow pattern of the liquid (corresponding to blood) within the outer needle assembly. As a result, it was confirmed that when the inner needle is pulled out from the outer needle from the puncture state of the inner needle shown in Figure 7(a) to the state shown in Figure 7(b), the liquid that flowed in from the needle tip of the outer needle is positioned so as to separate into the distal end and proximal end within the outer needle assembly, the discharge of air to the proximal end is inhibited by the liquid, and air remains between the liquid on the distal end side and the liquid on the proximal end side.

[0010] While investigating the reason why liquid introduced into the lumen of the outer needle assembly separates into the distal and proximal ends of the residual air, with air remaining in the middle of the liquid, the inventors focused on the presence of a stepped enlarged diameter portion on the inner circumferential surface of the outer needle assembly. The inventors presumed that if such a stepped enlarged diameter portion is provided in the lumen of the outer needle assembly, the cross-sectional area of ​​the lumen of the outer needle assembly through which the liquid flows will suddenly expand midway, resulting in the creation of a region in the enlarged diameter portion that is not filled with liquid. The inventors then considered that the liquid reaches the proximal end of the outer needle assembly while air remains in the region not filled with liquid, and the air vent path is blocked by the liquid, thereby inhibiting the discharge of air through the air vent path, causing air to remain in the middle part of the outer needle assembly, and resulting in a state in which liquid is present on both sides of the residual air. Furthermore, the inventors' investigations led them to believe that one of the reasons for the residual air is that when liquid flows through the stepped portion of the lumen of the outer needle assembly, turbulence is likely to occur due to a sudden change in the cross-sectional area of ​​the flow path, which causes air to be entrained in the liquid and makes it difficult to discharge the air.The inventors then completed the present invention based on these findings.

[0011] The following describes preferred embodiments for understanding the present invention, but the embodiments described below are merely examples and may be appropriately combined with one another. Multiple components described in each embodiment may be recognized and employed independently to the greatest extent possible, and may also be appropriately combined with any of the components described in other embodiments. Accordingly, the present invention is not limited to the embodiments described below, and various other embodiments may be realized.

[0012] A first aspect of the present invention is a catheter comprising a hollow outer needle through which an inner needle is inserted, and a flow path forming member connected to the outer needle, the flow path forming member has a flexible tube and a flow path connecting member, The flow path connection A valve body is provided inside the member, and a first internal space is provided on the distal end side of the valve body. the axial length from the valve body to the tip of the outer needle but 、 a second internal space on the base end side of the valve body; the axial length from the valve body to the base end of the flow path connecting memberan outer needle assembly having a length longer than that of the outer needle assembly, wherein an air vent path for releasing air in the first internal space to the outside is connected to the first internal space in the vicinity of the valve body, and the first internal space is comprised of a puncture section formed at a portion of the outer needle that has been punctured into a blood vessel, a tapered section formed proximal to the puncture section and having an inner diameter that increases toward the proximal end, and a tapered section formed proximal to the tapered section and having an inner diameter that is smaller than or equal to that of the proximal end of the tapered section. and the inner diameter is smaller than the inner diameter of the base end of the first internal space. and a small diameter portion. The small diameter portion includes a tip of the first internal space formed by the tube. There is something.

[0013] With an outer needle assembly constructed according to this aspect, the cross-sectional area of ​​the internal space in the small-diameter portion is the same as or smaller than the cross-sectional area of ​​the internal space at the base end of the tapered portion. Therefore, when blood flows into the small-diameter portion via the puncture portion and the tapered portion, the blood is less likely to bypass the air and cause partial leading, and the blood is more likely to flow across the entire cross section of the small-diameter portion. As a result, it is less likely that partially leading blood will pass through the small-diameter portion with air remaining, blocking the air vent before the air can escape. Instead of air remaining in the small-diameter portion, the blood pushes it out to the air vent and discharges it to the outside. Therefore, even when puncturing is performed with the needle tip pointing diagonally upward, air is less likely to remain in the first internal space distal to the valve body.

[0014] Furthermore, because the phenomenon of residual air is likely to occur when there is a large distance between the air vent passage and the outer needle, the configuration of this aspect, which can prevent residual air, is preferably applied to outer needle assemblies in which the air vent passage and the outer needle are arranged at a large distance from each other, for example by having a tubular member between the member holding the valve body and the member holding the outer needle. Furthermore, the configuration of this aspect is particularly preferably applied to outer needle assemblies in which the length of the small diameter portion is longer than the distance from the tip of the tapered portion to the tip of the small diameter portion. Furthermore, a large diameter portion, whose inner diameter is larger than that of the small diameter portion, may be formed proximal to the small diameter portion, and the large diameter portion may be adjacent to the valve body.

[0020] No. 2 The embodiment is 1 ofIn the outer needle assembly described in the aspect, the flow path forming member includes a flexible tube, and the tube is connected to the outer needle.

[0021] With an outer needle assembly constructed according to this aspect, when the outer needle assembly is inserted into a blood vessel or the like and left therein, the tube can be bent as necessary, for example, to easily connect the outer needle assembly to an external flow path such as a dialysis circuit or an infusion line.

[0022] No. 3 The embodiment is 2 In the outer needle assembly described in aspect (1), a large-diameter cylindrical portion with an increased inner diameter is provided at the tip portion of the tube, and the base end portion of the outer needle is fixed in an inserted state relative to the large-diameter cylindrical portion.

[0023] With an outer needle assembly constructed according to this aspect, by inserting and fixing the base end portion of the outer needle into the large-diameter cylindrical portion of the tube, it becomes easier to make the inner diameter dimension of the tube at the connection portion between the outer needle and the tube equal to or smaller than the inner diameter dimension of the outer needle.

[0024] No. 4 The embodiment is 3 In the outer needle assembly described in aspect 1, a small diameter cylindrical portion having smaller inner diameter dimensions and smaller outer diameter dimensions than the large diameter cylindrical portion is provided on the base end side of the large diameter cylindrical portion in the tube.

[0025] An outer needle assembly constructed in accordance with this aspect can prevent a sudden expansion of the inner diameter at the connection portion between the outer needle and the flow path forming member, while also preventing the flow path forming member from becoming unnecessarily thicker on the base end side of the connection portion with the outer needle.

[0026] No. 5 The first to second aspects are 4 The outer needle assembly according to any one of the above aspects, wherein the flow path forming member comprises a flexible tube, and no stepped expanded diameter portion is provided on the inner surface extending from the tip of the outer needle to the base end of the tube.

[0027] With the outer needle assembly constructed according to this aspect, a sudden increase in the inner diameter from the tip of the outer needle to the base end of the tube is avoided. This prevents a sudden change in volume in the internal space of the outer needle assembly, thereby preventing air from being entrained or trapped in the area of ​​such a sudden change in volume. The stepped portion with an increased diameter is a portion where the cross-sectional area of ​​the flow path changes suddenly, and includes, for example, a stepped surface that expands in the direction perpendicular to the axis.

[0028] No. 6 The embodiment of the present invention is a needle assembly including a flow path forming member connected to a needle, the flow path forming member having a flexible tube and a flow path connecting member, a valve body inside the flow path connecting member, and an axial length from the valve body to the tip of the needle in a first internal space on the tip side of the valve body is longer than an axial length from the valve body to the base end of the flow path connecting member in a second internal space on the base end side of the valve body, and an air vent for releasing air in the first internal space to the outside is provided in the first internal space near the valve body. and the first internal space comprises a puncture portion formed at the part of the needle that punctures the blood vessel, a tapered portion formed proximal to the puncture portion and having an inner diameter that increases toward the proximal end, and a small-diameter portion formed proximal to the tapered portion and having an inner diameter that is smaller than or the same as the proximal end of the tapered portion and smaller than the inner diameter of the proximal end of the first internal space, and the small-diameter portion includes the tip of the first internal space formed by the tube.

[0029] In the first embodiment, the outer needle and inner needle are combined, and the effect of preventing air from remaining in the lumen of the outer needle assembly having the outer needle is exerted, but the same effect is exerted in a needle assembly having a single needle as in the present embodiment, and the effect of preventing air from remaining in the lumen of the needle assembly having the needle is exerted. Note that this embodiment can be understood to be feasible by using the needle of this embodiment as the outer needle (48) in the embodiments described below. [Effects of the Invention]

[0030] According to the present invention, it is possible to prevent air from remaining in the lumen of the outer needle assembly. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 is a cross-sectional view showing an indwelling needle assembly according to a first embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a portion of the indwelling needle assembly shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view showing an outer needle assembly that constitutes the indwelling needle assembly shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view showing a state in which an external flow path is connected to the outer needle assembly shown in FIG. 3. [Figure 5] FIG. 10 is a cross-sectional view showing an outer needle assembly according to a second embodiment of the present invention. [Figure 6] FIG. 10 is a cross-sectional view showing an outer needle assembly according to a third embodiment of the present invention. [Figure 7] These are photographs taken during an experiment to observe the flow pattern of liquid within an outer needle assembly of a conventional structure, where (a) shows the state before the inner needle is pulled out from the outer needle, and (b) shows the state after the inner needle has been pulled out from the outer needle. DETAILED DESCRIPTION OF THE INVENTION

[0032] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0033] 1 and 2 show an indwelling needle assembly 12 equipped with an outer needle assembly 10 as a first embodiment of the present invention. The indwelling needle assembly 12 has a structure in which an inner needle assembly 14 and an outer needle assembly 10 are combined. In the following description, as a general rule, the axial direction refers to the left-right direction in Fig. 1, with the left end in Fig. 1 being the distal end and the right end in Fig. 1 being the proximal end.

[0034] The inner needle assembly 14 includes an inner needle 16. The inner needle 16 is a hollow metal needle, and has a beveled cutting edge 18 at its tip end, thereby forming an acute-angled needle tip 20. In Figure 1, the cutting edge 18 of the inner needle 16 is located on the upper side of the drawing.

[0035] An inner needle hub 22 is provided on the proximal end side of the inner needle 16. The inner needle hub 22 has a base portion 24 to which the proximal end portion of the inner needle 16 is fixed in an inserted state, and a protector accommodating portion 26 is provided on the distal end side of the base portion 24, and a connecting portion 28 is provided on the proximal end side of the base portion 24.

[0036] The protector housing portion 26 is cylindrical. A restricting cylindrical portion 30, which is generally cylindrical and has a larger diameter than the protector housing portion 26, is provided on the tip side of the protector housing portion 26. The outer peripheral surface of the protector housing portion 26 may be provided with anti-slip features such as protrusions, recesses, or embossments.

[0037] The connecting portion 28 is cylindrical, and the inner needle cap 32 is removably inserted and attached. The inner needle cap 32 has a generally stepped cylindrical shape with a step provided in the axially middle portion. A membrane filter 33 that allows the passage of gas but prevents the passage of liquid is provided at the tip portion of the inner needle cap 32, preventing backflow of blood through the inner needle 16 from leaking to the outside. If the inner needle hub 22 and the inner needle cap 32 are transparent or translucent, it is easy to confirm that a blood vessel has been punctured by backflow of blood (flashback).

[0038] A protector housing 34 is disposed on the inner periphery of the protector accommodating portion 26. The protector housing 34 comprises a cylindrical accommodating tube portion 36 and a lid 38 that closes an opening on the tip side of the accommodating tube portion 36. The lid 38 has a plate-shaped portion on the tip side and a plate-shaped portion on the base side that are spaced apart in the axial direction, and a needle tip protector 40 is disposed between these plate-shaped portions.

[0039] The needle tip protector 40 is composed of a shielding member 42 and a fixed member 44 housed in the protector housing 34. The shielding member 42 and the fixed member 44 are arranged apart from each other in the direction perpendicular to the axis, sandwiching the inner needle 16 therebetween. One of the shielding member 42 and the fixed member 44 is a magnet, and the other is a magnet or a ferromagnetic material, and a magnetic attractive force acts between the shielding member 42 and the fixed member 44, attracting them to each other. In this embodiment, the shielding member 42 is made of a ferromagnetic material such as iron, and the fixed member 44 is a permanent magnet. The fixed member 44 is fixed to the tip of the tubular housing portion 36. The shielding member 42 is displaceable in a direction approaching the fixed member 44, and when the inner needle 16 is inserted between the shielding member 42 and the fixed member 44, movement of the shielding member 42 toward the fixed member 44 is prevented by the inner needle 16. Then, when the inner needle 16 is pulled out further to the base end than the shielding member 42, the magnetic attractive force allows the shielding member 42 to move toward the fixed member 44, and the shielding member 42 moves to a position where it covers the needle tip 20 of the inner needle 16, and the shielding member 42 prevents the inner needle 16 from moving toward the tip end.

[0040] The inner needle 16 is inserted into the outer needle assembly 10 in a manner that allows it to be removed. The outer needle assembly 10 is a cylindrical body with a lumen 46 as an internal space that penetrates in the axial direction, and has an outer needle 48 and an outer needle hub 50 as a flow path-forming member that is connected in communication with the proximal end side of the outer needle 48.

[0041] The outer needle 48 is a hollow, small-diameter tube made of synthetic resin or the like. The outer peripheral surface of the outer needle 48 has a tapered shape with a diameter gradually decreasing toward the tip. As shown in FIG. 3 , the base end portion 51 of the outer needle 48 has a tapered first portion 52 that increases in diameter toward the base end, and a second portion 54 that is located more proximal than the first portion 52 and extends with approximately constant inner and outer diameters. That is, the outer needle 48 of this embodiment is a tapered, integrally formed, irregularly shaped tube that is integrally provided with the tapered first portion 52. The base end portion 51 of the outer needle 48 has a larger diameter than the tip end portion 55 of the outer needle 48 due to the tapered first portion 52. The base end portion 51 of the outer needle 48 in this embodiment has a gradually thicker wall at the first portion 52 toward the base end, and is thicker than the tip end portion 55 of the outer needle 48. The inner lumen of the outer needle 48 has a puncturing section 56 that extends with a substantially constant diameter at a tip section 55 that is inserted into a blood vessel, and a tapered section 57 whose inner diameter increases toward the base end at a first section 52 of the base end section 51 that is closer to the base end than the puncturing section 56. The inner circumferential surface of the outer needle 48 is configured as a smoothly continuous curved surface without forming any corners such as steps in the axial and circumferential directions. The tapered first section 52 (tapered section 57) only needs to increase in diameter overall toward the base end, and may have a constant taper angle, or the taper angle may vary in the axial direction.

[0042] Note that, although it depends on the thickness of the inner needle 16 inserted into the outer needle 48, etc., the axial length Y (see FIG. 3) of the first portion 52 having a tapered shape is relatively longer than the axial length X (see FIG. 3) of the second portion 54 extending substantially straight in the axial direction. For example, 1.5X ≤ Y, and in this embodiment, 2X < Y. Also, although the taper angle α of the first portion 52 is not limited, since the length dimension Y of the tapered first portion 52 is relatively long, the taper angle α of the first portion 52 is set relatively gently. Note that the taper angle α of the first portion 52 is the inclination angle with respect to the axial direction of a straight line connecting the base end of the tip portion 55 located on both sides of the first portion 52 and the tip of the second portion 54. Thus, by setting the taper angle α of the first portion 52 relatively gently, a rapid volume change in the internal space of the outer needle 48 is suppressed. Here, the axial length Y of the first portion 52 is the axial length between the tip portion 55 of the outer needle 48 and the second portion 54 that extend with substantially constant inner and outer diameter dimensions, respectively.

[0043] The outer needle hub 50 is generally cylindrical and has a structure in which the needle joining member 58 and the flow path connecting member 59 are connected by a tube 60.

[0044] The needle joining member 58 is formed of a hard synthetic resin. The needle joining member 58 has a tapered cylindrical shape that tapers toward the tip. The base end portion 51 of the outer needle 48 is inserted into the inner circumference of the needle joining member 58.

[0045] The flow path connecting member 59 has a cylindrical structure having a connection portion connected to an external flow path 104 described later at its base end. In this embodiment, it has a structure in which a valve body 64 and a pusher 66 are housed in a cylindrical valve housing 62.

[0046] The valve housing 62 is constituted by inserting the tip portion of a cylindrical pusher guide 70 into the base end portion of a cylindrical cover member 68, and connecting the cover member 68 and the pusher guide 70 in the axial direction.

[0047] A tube connecting member 72 is attached to and inserted into the cover member 68. The tube connecting member 72 is superimposed on and fixed to the inner circumferential surface of the distal end portion of the cover member 68. The proximal end of the tube connecting member 72 is positioned facing the cover member 68 at a distance inward. The proximal end of the tube connecting member 72 is provided with an annular tube fixing portion 73 that protrudes inward. The distal end face of the tube fixing portion 73 is an annular flat surface that abuts against the proximal end face of the tube 60, and the inner circumferential surface of the tube fixing portion 73 is a tapered surface 73a that gradually increases in diameter toward the proximal end. At the proximal end of the tapered surface 73a, a substantially cylindrical proximal end tubular portion 73b with a constant inner diameter is provided that protrudes toward the proximal end from the portion where the inner diameter is largest.

[0048] That is, the minimum inner diameter C1 (see FIG. 3) of the tapered surface 73a of the tube fixing portion 73 is larger than the inner diameter r1 of the tube 60 (described later), and the inner peripheral end portion of the tube 60 at the base end protrudes more inward than the inner peripheral end portion of the tube fixing portion 73. The minimum inner diameter C1 of the tapered surface 73a is smaller than the outer diameter of the tube 60. Furthermore, the inner diameter C2 (see FIG. 3) of the proximal end tubular portion 73b of the tube fixing portion 73 is larger than the minimum inner diameter C1 of the tapered surface 73a. In short, by providing the tube fixing portion 73 having the tapered surface 73a at the opening portion on the base end side of the tube 60, the inner diameter of the first internal space 78 (described later) increases stepwise or gradually toward the air passage 80. The axial dimension D (see FIG. 3) of the tube fixing portion 73 including the proximal end tubular portion 73b is set to be relatively small.

[0049] The plunger guide 70 has a base end portion that extends in the axial direction with a substantially constant cross-sectional shape, and a male screw portion 74 that protrudes toward the outer periphery is integrally formed at the base end (see FIG. 1).

[0050] As shown in Figure 3, the valve element 64 has a generally circular disk shape overall and is formed from an elastic material such as a resin elastomer or rubber. The valve element 64 has radial notches 76 formed in the center of the disk shape, and the notches 76 are opened and closed by elastic deformation of the center. The outer peripheral portion of the valve element 64 is axially sandwiched between the tip of the plunger guide 70 and a cylindrical valve support member 77 disposed on the inner periphery of the cover member 68. As a result, the valve element 64 is supported by the valve housing 62, and the lumen of the valve housing 62 is blocked by the valve element 64. As the lumen of the valve housing 62 is blocked by the valve element 64, the lumen 46 of the outer needle assembly 10 is divided into a distal side and a proximal side of the valve element 64, and the distal side of the lumen 46 from the valve element 64 is defined as a first internal space 78, and the proximal side of the lumen 46 from the valve element 64 is defined as a second internal space 79. The first internal space 78 is longer in the axial direction than the second internal space 79 .

[0051] Furthermore, when the valve body 64 is accommodated in the valve housing 62, the axial length D of the tube fixing portion 73 that supports the tube 60 from the proximal end side is relatively small, and therefore the proximal end surface of the tube 60 and the distal end surface of the valve body 64 face each other relatively closely in the axial direction. In particular, the tube fixing portion 73 is provided with a proximal end tubular portion 73b that protrudes toward the proximal end, and the axial distance between the proximal end tubular portion 73b and the distal end surface of the valve body 64 is smaller than the axial distance between the proximal end surface of the tube 60 and the distal end surface of the valve body 64. As will be described later, a first internal space 78 of the outer needle assembly 10 communicates with the air passage 80 through the gap between the proximal end tubular portion 73b and the distal end surface of the valve body 64. The proximal end of the tube 60 and the valve body 64 are relatively close to each other, and gas is easily guided outward in the circumferential direction by the valve body 64, making it difficult for air bubbles to remain.

[0052] The valve support member 77 is disposed at a position slightly spaced inwardly from the cover member 68, and a gap is provided radially between the valve support member 77 and the cover member 68. An air vent path 80, which connects the inner cavity 46 of the outer needle assembly 10 to the external space, is configured to include the gap between the valve support member 77 and the cover member 68. One end of the air vent path 80 connects to the first internal space 78 of the outer needle assembly 10 through the space between the tube connecting member 72 and the valve support member 77, and the other end connects to the external space through the space between the cover member 68 and the plunger guide 70. As a result, the portion of the inner cavity 46 of the outer needle assembly 10 further distal than the valve body 64 (first internal space 78) communicates with the external space via the air vent path 80. Furthermore, it is desirable that the cross-sectional area of ​​the air vent path 80 be small to allow the flow of gas and restrict the flow of liquid. Furthermore, the cross-sectional area of ​​the ventilation path 80 in this embodiment is increased in the middle portion, so that if blood enters the ventilation path 80, the blood will accumulate in the middle portion and will not easily leak into the external space from the ventilation path 80. The configuration of the ventilation path is not limited to this embodiment, and may be, for example, provided on the outer surface of the valve body, so that gas moves through the outer surface of the valve body to the base end side and is discharged into the external space.

[0053] Therefore, in this embodiment, the ventilation path 80 is provided on the outer periphery side of the valve body 64, and the opening of the ventilation path 80 on the first internal space 78 side is provided on the outer periphery side of the tube 60 and the tube fixing portion 73. At the base end portion of the tube 60, the inner diameter dimension is increased in stages by the tube fixing portion 73. In other words, at the base end portion of the tube 60, the inner diameter dimension increases from the base end opening of the tube 60 toward the ventilation path 80.

[0054] An air vent filter 82 is arranged in the air vent path 80. The air vent filter 82 is a filter that allows the passage of gas but restricts the passage of liquids such as blood, and is cylindrical or annular. The air vent filter 82 is arranged radially between the tube connecting member 72 and the valve support member 77 and the cover member 68, and is held in a radially compressed state. Because the air vent filter 82 is arranged on the air vent path 80, when the lumen 46 of the outer needle assembly 10 is filled with blood, the air vent filter 82 inhibits blood from entering the air vent path 80, preventing blood from leaking to the outside through the air vent path 80.

[0055] The plunger 66 is cylindrical and is inserted into the inner periphery of the plunger guide 70. The plunger 66 has a base end portion with a substantially constant outer diameter, and the outer circumferential surface of the tip portion has a tapered shape with the diameter decreasing toward the tip.

[0056] The tube 60 connecting the needle joint member 58 and the flow path connecting member 59 is a flexible soft tube made of a resin elastomer, rubber, or the like, which is bendable and allows for changes in cross-sectional shape. The provision of the tube 60 facilitates, for example, connecting the external flow path 104 to the outer needle hub 50 while the needle joint member 58 is fixed to the skin. The distal end of the tube 60 is fixed to the needle joint member 58, and the proximal end is inserted into and fixed to the inner periphery of a tube connecting member 72 attached to the flow path connecting member 59. This connects the needle joint member 58 and the flow path connecting member 59 via the tube 60, and the lumen of the flow path connecting member 59 is in communication with the lumen of the tube 60. The intermediate portion of the tube 60, located between the distal end and proximal end, is detached from both the needle joint member 58 and the flow path connecting member 59, allowing for deformation such as bending and crushing.

[0057] The proximal end portion 51 of the outer needle 48 is inserted into and connected to the distal end portion of the tube 60. In this embodiment, the distal end portion of the tube 60 is fixedly sandwiched radially between the proximal end portion 51 of the outer needle 48 and the needle joint member 58, and the outer needle hub 50 including the needle joint member 58 and the tube 60 is connected to the proximal end side of the outer needle 48. The method of fixing the needle joint member 58, the proximal end portion 51 of the outer needle 48, and the distal end portion of the tube 60 is not limited, but for example, the proximal end portion 51 of the outer needle 48 is inserted in a press-fit state into the large-diameter cylindrical portion 84 of the tube 60 and bonded as necessary. Furthermore, a protrusion on the inner surface of the needle joint member 58 may be used to position the insertion end of the tube 60 in the needle joint member 58 or to clamp and hold the large-diameter cylindrical portion 84. The inner cavity of the outer needle 48 and the inner cavity of the outer needle hub 50 are interconnected, and the inner cavity 46 of the outer needle assembly 10 is configured to include the inner cavity of the outer needle 48 and the inner cavity of the outer needle hub 50.

[0058] The tube 60 has a large-diameter cylindrical portion 84 at its tip end portion, which is fixed to the outer needle 48, and has an inner diameter larger than that of a portion located away from the outer needle 48 toward the proximal end. The tube 60 has a substantially constant outer diameter in the axial direction, and therefore is thin-walled at the large-diameter cylindrical portion 84. The tube 60 has an annular stepped surface 86 that connects the inner circumferential surface of the large-diameter cylindrical portion 84 with the inner circumferential surface of the portion that is away from the large-diameter cylindrical portion 84 toward the proximal end. The stepped surface 86 is provided on the inner circumferential portion of the tube 60 and widens in the direction perpendicular to the axis. The tube 60 has a substantially constant inner diameter r1 (described below) on the proximal end side of the stepped surface 86.

[0059] The outer needle 48 is fixed in an inserted state to the tube 60, with the second portion 54 constituting the base end portion 51 inserted into the inner periphery of the large-diameter cylindrical portion 84. In other words, the large-diameter cylindrical portion 84, which is the tip portion of the tube 60, is held in a state of being radially sandwiched between the second portion 54 of the outer needle 48 and the needle joint member 58. The outer peripheral surface of the second portion 54 of the outer needle 48 is superimposed in abutting contact with the inner periphery of the large-diameter cylindrical portion 84 of the tube 60. The base end surface of the outer needle 48 abuts against the stepped surface 86 of the tube 60 in the axial direction, thereby positioning the outer needle 48 and the tube 60 relative to each other in the axial direction. That is, in the present embodiment, the outer needle 48 and the tube 60 are in direct abutment with each other. Note that an outer needle fixing member or the like that presses and fixes the outer needle 48 against the large-diameter cylindrical portion 84 is not provided on the inner periphery of the outer needle 48, and the formation of a step that would be caused by arranging the outer needle fixing member on the inner periphery of the outer needle 48 is avoided, thereby preventing air from being entrained into the blood due to the step. Furthermore, in the present embodiment, by setting the taper angle α of the tapered portion 57 of the outer needle 48 to a relatively gentle angle, it is also possible to prevent air from being entrained or retained due to a sudden change in volume in the internal space of the outer needle 48. In particular, if the taper angle α is 30 degrees or more or 45 degrees or more, a substantially stepped shape will be formed, raising concerns about air being entrained or retained.

[0060] At the connection portion 88 between the outer needle 48 and the tube 60, the inner diameter dimension r1 of the tube 60 is set to be not more than the inner diameter dimension r2 of the outer needle 48 (r1≦r2). In other words, the radial width dimension t1 of the stepped surface 86, which is the size obtained by dividing by 2 the difference obtained by subtracting the inner diameter dimension r1 of the tube 60 at the connection portion 88 between the outer needle 48 and the tube 60 from the inner diameter dimension r3 at the proximal end of the large-diameter cylindrical portion 84 in the tube 60 (t1=(r3-r1) / 2), is set to be not less than the thickness dimension t2 at the proximal end of the outer needle 48 (t1≧t2). In the present embodiment, at the connection portion 88 between the outer needle 48 and the tube 60, the inner diameter dimension r1 of the tube 60 is made smaller within a range where it can be regarded as substantially the same as the inner diameter dimension r2 at the proximal end of the outer needle 48. Preferably, the inner diameter dimension r1 of the tube 60 is set to be 2.6 mm or less, and more preferably, the inner diameter dimension r1 of the tube 60 is set to be 2.5 mm or less. Also preferably, the inner diameter dimension r2 of the outer needle 48 is set such that 2.5 mm≦r2≦3.3 mm. More preferably, the inner diameter dimension r2 of the outer needle 48 is, for example, 2.9 mm, and is made larger than the inner diameter dimension r1 of the tube 60. Further, the inner diameter dimension of the tube 60 is made substantially constant from the connection portion 88 between the outer needle 48 and the tube 60 to the proximal end of the tube 60, and the inner diameter dimension of the outer needle hub 50 is set to be not more than the inner diameter dimension r2 at the proximal end of the outer needle 48 from the connection portion 88 between the outer needle 48 and the tube 60 to the proximal end of the tube 60.

[0061] Also, as described above, the inner diameter dimension A (see FIG. 3) of the tip portion 55 (puncturing portion 56) in the outer needle 48 is not more than the inner diameter dimension of the tapered portion 57 in the outer needle 48, and is made smaller than the inner diameter dimension r1 of the tube 60 and the inner diameter dimension r2 at the proximal end of the outer needle 48 (A<r1≦r2). By doing so, it is possible to achieve both a flow rate and a low likelihood of air bubble residue.

[0062] In addition, the inner diameter dimension A of the puncture portion 56 of the outer needle 48 depends on, for example, the thickness of the inner needle 16 inserted into the outer needle 48, etc., but it is preferably set such that, for example, (inner diameter dimension r1 of the tube 60) < (1.5 × A). Thereby, the change in the cross-sectional area of the internal space in the outer needle 48 can be reduced, and it becomes difficult to entangle air bubbles. Also, it is preferably set such that (6 × A) < (axial length Y of the tapered portion 57). Thereby, since the axial length Y of the tapered portion 57 can be ensured to be sufficiently large, the tapered portion 57 can be formed into a shape that gradually expands in diameter, and the remaining of air bubbles can be suppressed. Further, the inner diameter dimension r1 of the tube 60 is preferably set such that, for example, (inner diameter dimension C2 of the proximal end cylindrical portion 73b) < (2 × r1). Also, the inner diameter dimension r1 of the tube 60 is preferably set such that, for example, (axial length E between the valve body 64 and the tube 60) < (2 × r1). Thereby, the valve body 64 and the tube 60 can be arranged close to each other. In the present embodiment, (axial length E between the valve body 64 and the tube 60) is made smaller than the inner diameter dimension r1 of the tube 60. Furthermore, the inner diameter dimension r1 of the tube 60 is preferably set such that, for example, (axial length D of the tube fixing portion 73) < r1. Also by this, it is possible to arrange the valve body 64 and the tube 60 in a relatively close state. Note that in the first internal space 78, an air passage 80 opens on the front surface of the valve body 64. Also, since the inner diameter dimension r1 of the tube 60 and the inner diameter dimension r2 of the proximal end of the outer needle 48 can be regarded as substantially the same, the same relationship as described above is considered to hold for the inner diameter dimension r2 of the proximal end of the outer needle 48. That is, the inner diameter dimension r2 of the proximal end of the outer needle 48 is preferably set such that (inner diameter dimension r2 of the proximal end of the outer needle 48) < (1.5 × A). Also, the inner diameter dimension r2 of the proximal end of the outer needle 48 is preferably set such that, for example, (inner diameter dimension C2 of the proximal end cylindrical portion 73b) < (2 × r2). Furthermore, the inner diameter dimension r2 of the proximal end of the outer needle 48 is preferably set such that, for example, (axial length E between the valve body 64 and the tube 60) < (2 × r2). Further, the inner diameter dimension r2 of the proximal end of the outer needle 48 is preferably set such that, for example, (axial length D of the tube fixing portion 73) < r2.

[0063] The connection portion 88 between the outer needle 48 and the tube 60 is a portion that forms the boundary between the outer needle 48 and the tube 60 on the inner surface of the internal flow path of the outer needle assembly 10. The connection portion 88 between the outer needle 48 and the tube 60 in this embodiment is provided at a portion where the base-end surface of the outer needle 48 and the step surface 86 of the tube 60 are located in the axial direction. The connection portion 88 between the outer needle 48 and the tube 60 may include a portion of the tube 60 that is adjacent to the base end side of the large-diameter cylindrical portion 84. However, what is of interest in the present invention is the internal flow path (lumen 46) of the outer needle assembly 10, that is, the internal surface of the internal flow path, and therefore, for example, the tapered shape of the outer needle 48 and the connection portion 88 between the outer needle 48 and the tube 60 should also be understood as the internal flow path internal surface (inner circumferential surface) of the internal flow path.

[0064] The portion of the lumen 46 of the outer needle assembly 10 that is distal to the valve body 64 is a small-diameter portion 89 that is provided proximal to the proximal end of the tapered portion 57 of the outer needle 48 and has a smaller diameter than the proximal end of the tapered portion 57. The small-diameter portion 89 is continuous in the axial direction from the connection portion 88 between the outer needle 48 and the tube 60 to the proximal end of the tube 60. The small-diameter portion 89 extends with a substantially constant diameter, and the portion of the inner circumferential surface of the tube 60 that forms the small-diameter portion 89 is cylindrical. The small-diameter portion 89 has a longer axial length than the tapered portion 57 of the outer needle 48. The first internal space 78 in the lumen 46 of the outer needle assembly 10 distal to the valve body 64 includes the puncturing portion 56 and tapered portion 57 that form the lumen of the outer needle 48, and the small-diameter portion 89 that forms the lumen of the tube 60.

[0065] The inner needle 16 is inserted from the proximal end side into the inner cavity 46 of the outer needle assembly 10, which is configured to include the inner cavity of the outer needle 48 and the inner cavity of the outer needle hub 50. As shown in Figures 1 and 2, the inner needle 16 pushes open the slit 76 of the valve body 64 disposed in the inner cavity 46 of the outer needle assembly 10, and penetrates the slit 76.

[0066] The inner needle assembly 14 equipped with the inner needle 16 and the outer needle assembly 10 equipped with the outer needle 48 are connected by a connector cap 90. The connector cap 90 has a bottom wall portion 92 extending in the direction perpendicular to the axis. The bottom wall portion 92 is in the shape of an annular plate, and a tubular projection 94 projecting toward the distal end is integrally formed at the inner peripheral end portion. A circumferential wall portion 96 extending toward the distal end and a pair of elastic pieces 98, 98 extending toward the base end are integrally formed at the outer peripheral end portion of the bottom wall portion 92.

[0067] An internal thread 100 is provided on the inner peripheral surface of the cylindrical circumferential wall portion 96. The base end portion of the plunger guide 70 that constitutes the outer needle hub 50 is inserted into the inner periphery of the circumferential wall portion 96, and the external thread portion 74 of the plunger guide 70 and the internal thread 100 of the circumferential wall portion 96 are threadedly engaged, thereby attaching the connector cap 90 to the base end portion of the outer needle hub 50.

[0068] When the inner needle assembly 14 and the outer needle assembly 10 are assembled, the restricting cylindrical portion 30 of the inner needle hub 22 is fitted onto the connector cap 90. As a result, the restricting cylindrical portion 30 restricts the deformation of the elastic pieces 98, 98 toward the outer periphery, and the connection between the connector cap 90 and the protector housing 34 by the pair of locking projections 102, 102 is stably maintained.

[0069] In the indwelling needle assembly 12 constructed as described above, the inner needle 16 is inserted into a blood vessel in a patient's arm (not shown) or the like. The medical professional (user) performing the blood vessel insertion holds the inner needle hub 22 with their fingers and inserts the inner needle 16 into the patient's arm or the like. After the inner needle 16 and the outer needle 48 have inserted into the patient's blood vessel, the inner needle 16 is removed from the outer needle 48, and the outer needle assembly 10 is left indwelling with the outer needle 48 inserted in the patient's blood vessel.

[0070] The lumen 46 of the outer needle assembly 10 is filled with air before the inner needle 16 and the outer needle 48 puncture the area. When the inner needle 16 is removed from the outer needle 48, blood flows into the lumen 46 of the outer needle assembly 10 from the tip opening of the outer needle 48. Here, at a connection portion 88 between the outer needle 48 and the tube 60 on the inner surface of the wall of the lumen 46 of the outer needle assembly 10, the inner diameter dimension r1 of the tube 60 is the same as or smaller than the inner diameter dimension r2 of the base end of the outer needle 48. Therefore, no stepped expanded diameter portion is provided on the inner surface of the wall of the lumen 46 of the outer needle assembly 10 at the connection portion 88 between the outer needle 48 and the tube 60. Therefore, a residual area of ​​air not filled with blood is unlikely to be formed near the connection portion 88 between the outer needle 48 and the tube 60, and the lumen 46 of the outer needle assembly 10 can be filled with blood. It is preferable that the inner diameter r1 of the tube 60 is smaller than the inner diameter r2 of the base end of the outer needle 48, since air bubbles are less likely to remain.

[0071] When the outer needle is inserted into a blood vessel and the outer needle assembly is in an inclined state with its tip positioned above its base end, if a stepped enlarged-diameter portion with a larger diameter on the base end side is provided at the connection portion of the inner lumen of the outer needle assembly between the outer needle and the tube, blood will not easily flow into the enlarged-diameter portion and air will likely remain. According to the outer needle assembly 10 of this embodiment, there is no stepped enlarged-diameter portion in the inner lumen 46 of the outer needle assembly 10 at the connection portion 88 between the outer needle 48 and the tube 60, and air is efficiently pushed toward the base end by the blood, so that air is discharged to the outside through the air vent 80 without remaining in the inner lumen 46. Note that, for example, when multiple outer needle assemblies are indwelled, such as an indwelling needle on the blood removal side and an indwelling needle on the blood return side connected to a dialysis circuit, at least one outer needle assembly can be oriented so that its tip is positioned above.

[0072] Furthermore, at the connection portion 88 between the outer needle 48 and the tube 60, no stepped portion with an increased diameter is formed on the inner wall surface of the lumen 46 of the outer needle assembly 10, thereby reducing the occurrence of turbulence due to a sudden increase in cross-sectional area. This reduces air entrainment due to turbulence, and suppresses air from remaining in the lumen 46 of the outer needle assembly 10. In particular, in the present embodiment, no stepped portion with an increased diameter or portion with a suddenly increasing taper angle is provided on the inner circumferential surface of the outer needle assembly 10 from the distal end of the outer needle 48 to the proximal end of the tube 60, thereby suppressing a sudden change in volume in the lumen 46 and further preventing air entrainment, retention, etc. Note that it is preferable that no stepped portion with an increased diameter that exceeds the wall thickness of the outer needle is provided in the lumen 46 of the outer needle assembly 10 of this embodiment.

[0073] The base end portion 51 of the outer needle 48 has a first portion 52 whose inner circumferential surface is gently tapered, and the inner diameter of the base end portion 51 increases toward the base end. As a result, the blood flow rate is slower at the base end of the outer needle 48 located at the connection portion 88 between the outer needle 48 and the tube 60 than at the tip end of the outer needle 48, so that air is more reliably pushed out toward the base end by the blood, turbulence is more easily prevented, and air is more effectively prevented from remaining in the lumen 46.

[0074] The connection portion 88 between the outer needle 48 and the tube 60 is not only a location where the flow rate suddenly decreases as the proximal end portion 51 of the outer needle 48 expands in a tapered shape, but also a location where a stepped expansion in diameter is likely to occur, making it prone to separation of the blood in the flow path by air. In addition, the connection portion 88 is located away from the air vent 80 toward the distal end. Therefore, if air remains or is entrained due to expansion in diameter at the connection portion 88 between the outer needle 48 and the tube 60, the remaining air is unlikely to reach the air vent 80 and is likely to remain in the lumen 46 of the outer needle assembly 10. Therefore, rapid expansion of the lumen 46 toward the proximal end at the connection portion 88 between the outer needle 48 and the tube 60 is prevented, thereby suppressing air from remaining or being entrained at the connection portion 88 between the outer needle 48 and the tube 60. This prevents air from remaining in the lumen 46 of the outer needle assembly 10, and enables the lumen 46 to be filled with blood. The lumen 46 of the outer needle assembly 10 of this embodiment expands in diameter in a stepped manner at the proximal end of the tube 60, but this expanded diameter portion is away from the tapered proximal end portion 51 of the outer needle 48 and is provided at a position closer to the air vent 80 than the connection portion 88 between the outer needle 48 and the tube 60, making it less likely that air will remain in the lumen 46. In particular, in this embodiment, the air vent 80 is provided on the outer peripheral side of the tube 60, and the lumen 46 of the outer needle assembly 10 expands in diameter in a stepped manner or gradually at the proximal end of the tube 60, thereby expanding in the direction toward the air vent 80.

[0075] In the first internal space 78 of the outer needle assembly 10, the inner diameter dimension of a small-diameter section 89 formed proximal to the tapered section 57 is smaller than the inner diameter dimension of the proximal end of the tapered section 57. As a result, when blood flows from the proximal end of the tapered section 57, which has a large flow path cross-sectional area, into the small-diameter section 89, which has a small flow path cross-sectional area, the blood does not flow first in part of the flow path cross-section of the small-diameter section 89, but flows into the entire flow path cross-section of the small-diameter section 89, and the blood is less likely to flow around to the proximal end side, leaving air behind. Therefore, the air vent path 80, which opens proximal to the small-diameter section 89 and opens near the valve body 64, is not blocked by the blood that has flowed first, and air is effectively discharged through the air vent path 80, preventing air from remaining in the first internal space 78 when blood is introduced.

[0076] With the outer needle assembly 10 separated from the inner needle 16 and placed in place, the connector cap 90 is removed from the outer needle hub 50, and as shown in FIG. 4 , the male connector 106 that constitutes the external flow path 104 is inserted into the plunger guide 70 of the outer needle hub 50 from the proximal end side. Furthermore, a locking portion (not shown) provided on the male connector 106 that constitutes the external flow path 104 is screwed into the male threaded portion 74 provided on the flow path connecting member 59 of the outer needle hub 50. This connects the outer needle assembly 10 and the external flow path 104, and the lumen 46 of the outer needle assembly 10 communicates with the external flow path 104. In this way, the male threaded portion 74 of the outer needle hub 50 is used both to connect the connector cap 90 to the outer needle hub 50 and to connect the external flow path 104 to the outer needle hub 50. The male connector 106 does not have to have a locking portion (not shown), and the male connector 106 and the plunger guide 70 can be connected by fitting the male connector 106 into the base end of the plunger guide 70.

[0077] When the male connector 106 is connected to the outer needle hub 50, the plunger 66 is pushed toward the tip side by the male connector 106. The pushed-in plunger 66 is pressed against the valve body 64, deforming the valve body 64 and opening the notch 76 in the valve body 64. This connects the patient's blood vessel to the external flow path 104 through the lumen 46 of the outer needle assembly 10, allowing treatment such as hemodialysis, blood sampling, and administration of medicinal solutions to be performed.

[0078] 4 is connected to the outer needle assembly 10, the valve body 64 is pushed open by the plunger 66 and covers the opening of the air vent path 80 on the lumen 46 side, and the air vent path 80 is blocked by the valve body 64. This prevents blood, medicinal liquid, and the like from leaking to the outside through the air vent path 80. However, blocking the air vent path 80 by the valve body 64 is not essential.

[0079] Figure 5 shows an outer needle assembly 110 as a second embodiment of the present invention. The outer needle assembly 110 includes a tube 112. In the following description, components and parts that are substantially the same as those in the first embodiment are denoted by the same reference numerals in the drawings, and description thereof will be omitted.

[0080] The tube 112 has a structure in which a small-diameter cylindrical portion 114 is provided continuously with the base end side of a large-diameter cylindrical portion 84 that constitutes the tip portion. The small-diameter cylindrical portion 114 is generally cylindrical, and its inner and outer diameters are generally constant in the axial direction. Both the inner and outer diameters of the small-diameter cylindrical portion 114 are smaller than those of the large-diameter cylindrical portion 84. In this embodiment, the small-diameter cylindrical portion 114 has approximately the same thickness as the large-diameter cylindrical portion 84, but the small-diameter cylindrical portion 114 may be thicker or thinner than the large-diameter cylindrical portion 84.

[0081] A thick-walled connecting portion 116 is provided on the base end side of the small-diameter cylindrical portion 114. The thick-walled connecting portion 116 has an outer diameter dimension that is approximately the same as that of the large-diameter cylindrical portion 84, and an inner diameter dimension that is approximately the same as that of the small-diameter cylindrical portion 114, and protrudes outward more radially than the small-diameter cylindrical portion 114, making it thicker. The small-diameter cylindrical portion 114, which is the axially intermediate portion of the tube 112, has an outer diameter dimension that is smaller than that of the large-diameter cylindrical portion 84 and the thick-walled connecting portion 116, which are both end portions.

[0082] According to the outer needle assembly 110 constructed in accordance with this embodiment, as in the first embodiment, the tube 112 side does not have a larger diameter at the connection portion 88 between the outer needle 48 and the tube 112, and air is prevented from remaining in the lumen 46 of the outer needle assembly 110 when blood flows in.

[0083] Furthermore, the tube 112 has a smaller diameter at the small diameter cylindrical portion 114 provided on the proximal side of the portion fixed to the outer needle 48 than the large diameter cylindrical portion 84 fixed to the outer needle 48. Therefore, by making the inner diameter dimension of the tube 112 at the small diameter cylindrical portion 114 equal to or smaller than the inner diameter dimension of the proximal end of the outer needle 48, and by thinning the small diameter cylindrical portion 114, it is possible to save on forming material.

[0084] By making the tube 112 thin-walled at the small diameter cylindrical portion 114, it is possible to reduce the elasticity of the small diameter cylindrical portion 114 and make it easy to deform the small diameter cylindrical portion 114. Therefore, it is possible to easily connect the outer needle hub 50 to an external flow path (not shown) by bending the tube 112.

[0085] An outer needle assembly 120 as a third embodiment of the present invention is shown in Figure 6. An outer needle hub 122 serving as a flow path forming member in this embodiment is provided with a branching member 126 having a branching portion 124, and at this branching portion 124, the main flow path extending from the outer needle 48 to the base end side branches off laterally, forming a branched port portion 132 equipped with a branched flow path.

[0086] 6 shows a state in which the inner needle (16) has been pulled out, as in FIGS. 3 and 5. In addition, in this embodiment, the connection portion between the proximal end side of the outer needle 48 and the outer needle hub 122 (near the area indicated by reference numeral 58 in FIG. 6) is substantially the same as the structure shown in FIG. 3 of the first embodiment, and therefore the internal structure is not shown. That is, in this embodiment, the internal structure at the connection portion between the proximal end portion of the outer needle 48 and the outer needle hub 122 is such that the tube 60 in the first embodiment is replaced with a branching member 126. More specifically, a large-diameter cylindrical portion (corresponding to the large-diameter cylindrical portion 84 in FIG. 3) with an increased inner diameter is provided at the distal end portion of the branching member 126, and the proximal end portion (51) of the outer needle 48 is inserted into the large-diameter cylindrical portion of the branching member 126 and fixed in an inserted state to the branching member 126 (corresponding to the tube 60 in FIG. 3). Here, the inner diameter dimension of the branching member 126 (corresponding to the inner diameter dimension r1 of the tube 60 in the first embodiment) is made the same as or smaller than the inner diameter dimension r2 of the proximal end of the outer needle 48, thereby providing a small diameter portion (89) at the connection portion between the proximal side of the outer needle 48 and the outer needle hub 122. Furthermore, the connection portion of the external flow path (104) at the proximal side of the outer needle hub 122 (near the area indicated by reference numeral 59 in Figure 6) is substantially the same as the structure shown in Figures 3 and 4 in the first embodiment, and therefore illustration and description of the internal structure will be omitted. Furthermore, in this embodiment, the branch port portion 132 provided at the proximal end of the branching flow path is substantially the same as the connection port portion 134 provided at the proximal end of the main flow path, and therefore illustration and description of the internal structure will be omitted.

[0087] Incidentally, the base end side (right side in FIG. 6 ) of the branching member 126 is connected to the main flow path and the branching flow paths via the flow path connecting member 59 via the tube 112. The tube 112 has a small-diameter cylindrical portion 114, as in the second embodiment. As shown in the enlarged cross-sectional view in FIG. 6 , the tip of the tube 112 is fitted into and fixed to the lumen 46 (main flow path) of the branching member 126. In this embodiment, the tube 112 has an expanded diameter portion whose inner diameter is expanded toward the tip end, and the diameter of the distal end opening of the expanded diameter portion is smaller than the inner diameter of the main flow path in the branching member 126. As a result, as can be seen from the enlarged cross-sectional view in FIG. 6 , the diameter at the connection portion between the main flow path and the tube 112 in the branching member 126 decreases in a stepped manner from the tip end toward the base end. Furthermore, in the internal flow path of the tube 112, the base end side of the expanded diameter portion also decreases in a stepped manner toward the flow path connecting member 59.

[0088] However, because the outer needle assembly 120 of this embodiment also has a substantially stepped small-diameter portion (89) located at the connecting portion (88) on the base end side of the outer needle 48, similar to the first embodiment, the above-mentioned effects of the present invention can be achieved without providing a stepped small-diameter portion on the base end side of the branching member 126. Therefore, the flow path on the base end side of the branching member 126 may have a substantially constant inner diameter, and because it is separated from the tapered base end portion 51 of the outer needle 48 and is close to the air passage 80, problems of air being entrained in or remaining in the circulating liquid are unlikely to occur even if the diameter of the flow path increases from the tip end side to the base end side.

[0089] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the specific descriptions. For example, the configuration of the present invention may be adopted by providing a valve and an air passage inside the proximal connector of an indwelling needle as disclosed in Japanese Patent Application Laid-Open No. 2004-298622 or Japanese Patent Application Laid-Open No. 2014-108112.

[0090] If the outer diameter dimension of the second portion 54 connected to the tube 60 at the base end portion 51 of the outer needle 48 is smaller than the outer diameter dimension at the base end of the first portion 52, stepped expansion of the diameter at the connection portion 88 between the outer needle 48 and the tube 60 is avoided even if the radial width dimension of the stepped surface 86 provided on the inner surface of the tube 60 is smaller than the thickness dimension of the base end of the outer needle 48.

[0091] The outer needle 48 may be connected in an externally fitted state to the tube 60. In this case, it is desirable to reduce the step formed at the connection portion 88 between the outer needle 48 and the tube 60, for example, by reducing the outer diameter dimension of the tip portion of the tube 60 to make it thinner, or by increasing the inner diameter dimension of the base end portion 51 of the outer needle 48 to make it thinner. The outer needle 48 may be butted against the tube 60 in the axial direction and connected by means of welding or the like.

[0092] The tube 60 does not need to have a constant thickness, for example, between the needle joining member 58 and the flow path connecting member 59, and may have an inner circumferential surface that gradually protrudes inward toward the center in the axial direction, becoming thicker.

[0093] The outer peripheral surface of the portion of the inner needle 16 that is inserted into the tube 60 can be provided with a non-slip surface that makes it less likely to slip against the inner peripheral surface of the tube 60, for example, by roughening the surface with unevenness or texture, or by coating with an elastomer, rubber, synthetic resin, or the like that has high frictional resistance. In this way, when the tube 60 is grasped, slippage between the tube 60 and the inner needle 16 is less likely to occur, and the relative positions of the inner needle 16 and the outer needle 48 are less likely to shift. Note that the structure that makes it less likely to slip against the inner peripheral surface of the tube 60 (non-slip surface) does not have to be provided on the outer peripheral surface of the inner needle 16; it may be provided on the inner peripheral surface of the tube 60, for example. In short, the non-slip surface is provided between the inner needle 16 and the tube 60, in other words, on at least one of the outer peripheral surface of the inner needle 16 and the inner peripheral surface of the tube 60.

[0094] The flow path forming member does not necessarily require a flexible tube, and may have a structure in which the valve body is housed in a rigid flow path forming member as a whole. Specifically, for example, a structure in which the needle joint member and the flow path connecting member are directly fixed without an intervening tube may be employed.

[0095] As shown in the above embodiment, it is desirable that the air vent path 80 be provided with an air vent filter 82 to prevent blood leakage, but an air vent filter may not be provided if blood leakage can be prevented by, for example, the cross-sectional area or cross-sectional shape of the air vent path. Furthermore, the air vent path is not limited to a structure extending between components of the flow path forming member, and may be, for example, a hole structure that penetrates the components of the flow path forming member. The present invention originally includes all of the inventions described in (i) to (viii) below, and the configurations and effects thereof will be described below. The present invention provides (i) An outer needle assembly comprising: a hollow outer needle through which an inner needle is inserted; and a flow path forming member connected to the outer needle, the flow path forming member having a valve body inside, a first internal space distal to the valve body that is longer than a second internal space proximal to the valve body, the first internal space being longer than the valve body; an air passage for releasing air from the first internal space to the outside that communicates with the first internal space near the valve body; and the first internal space comprising: a puncture section formed at a portion where the outer needle punctures a blood vessel; a tapered section formed proximal to the puncture section and having an inner diameter that increases toward the proximal end; and a small-diameter section formed proximal to the tapered section and having an inner diameter that is smaller than or the same as the proximal end of the tapered section. (ii) An outer needle assembly comprising a hollow outer needle through which an inner needle is inserted and a flow path forming member connected to the outer needle, the flow path forming member having a valve body inside, and the flow path forming member having an air passage that connects the internal space distal to the valve body to the outside, wherein the base end portion of the outer needle has a tapered shape that expands in diameter toward the base end, and the inner diameter dimension of the flow path forming member at the connection portion between the outer needle and the flow path forming member is equal to or smaller than the inner diameter dimension of the outer needle; (iii) The outer needle assembly according to (ii), wherein the inner diameter of the flow path forming member and the inner diameter of the outer needle are the same at the connection portion between the outer needle and the flow path forming member. (iv) The outer needle assembly according to any one of (i) to (iii), wherein the flow path forming member includes a flexible tube, and the tube is connected to the outer needle. (v) The outer needle assembly according to (iv), wherein a large-diameter cylindrical portion having an increased inner diameter is provided at the distal end portion of the tube, and the proximal end portion of the outer needle is fixed in an inserted state relative to the large-diameter cylindrical portion. (vi) The outer needle assembly according to (v), wherein a small-diameter cylindrical portion having smaller inner and outer diameter dimensions than the large-diameter cylindrical portion is provided on the proximal side of the large-diameter cylindrical portion in the tube; (vii) The outer needle assembly according to any one of (i) to (vi), wherein the flow path forming member comprises a flexible tube, and no stepped diameter-enlarging portion is provided on the inner circumferential surface extending from the tip end of the outer needle to the base end of the tube. (viii) A needle assembly comprising a flow path forming member connected to a needle, a valve body inside the flow path forming member, a first internal space distal to the valve body that is longer than a second internal space proximal to the valve body, an air passage for releasing air from the first internal space to the outside that communicates with the first internal space near the valve body, and the first internal space comprising: a puncture portion formed at a portion of the needle that punctures a blood vessel; a tapered portion formed proximal to the puncture portion and having an inner diameter that increases toward the proximal end; and a small-diameter portion formed proximal to the tapered portion and having an inner diameter that is smaller than or equal to the base end of the tapered portion. This includes inventions relating to: In the invention described in (i) above, the cross-sectional area of ​​the internal space in the small-diameter portion is the same as or smaller than the cross-sectional area of ​​the internal space at the proximal end of the tapered portion. Therefore, when blood flows into the small-diameter portion via the puncture portion and the tapered portion, the blood is less likely to bypass the air and flow partially ahead, allowing the blood to flow easily across the entire cross section of the small-diameter portion. As a result, it is less likely that partially ahead blood will pass through the small-diameter portion while retaining air, blocking the air vent before the air is released. Air in the small-diameter portion is pushed out to the air vent and discharged to the outside without remaining. Therefore, even when puncturing is performed with the needle tip pointing obliquely upward, air is less likely to remain in the first internal space distal to the valve body. Note that air retention is likely to occur when the air vent and the outer needle are separated by a large distance. Therefore, the configuration of this embodiment, which can prevent air retention, is preferably applied to outer needle assemblies in which the air vent and the outer needle are separated by a large distance, for example, by providing a tubular member between the member holding the valve body and the member holding the outer needle. Furthermore, the configuration of this aspect is particularly suitable for use in an outer needle assembly in which the length of the small diameter portion is longer than the distance from the tip of the tapered portion to the tip of the small diameter portion. Furthermore, a large diameter portion having an inner diameter larger than that of the small diameter portion may be formed proximal to the small diameter portion, and the large diameter portion may be adjacent to the valve body. In the invention described in (ii) above, no expanded diameter portion with a larger diameter on the proximal side is formed at the connection between the outer needle and the flow path forming member. Therefore, at the connection between the outer needle and the flow path forming member in the lumen of the outer needle assembly, a region that is not filled with liquid introduced from the outer needle into the flow path forming member is unlikely to be formed, and residual air is suppressed. Furthermore, because the proximal end portion of the outer needle has a tapered shape that expands in diameter toward the proximal end, the flow rate of the liquid flowing through the outer needle decreases as it approaches the proximal end. As a result, the generation of turbulence due to the flow of liquid at the proximal end of the outer needle is further suppressed, preventing air from being entrained in the liquid. In the invention described in (iii) above, the formation of a step is prevented at the connection portion between the outer needle and the flow path forming member, thereby further reducing the occurrence of turbulence in the liquid flowing through the inner cavity of the outer needle assembly and suppressing the entrainment of air. In the invention described in (iv) above, when the outer needle assembly is inserted into a blood vessel or the like and left there, the tube can be bent as necessary, for example, so that the outer needle assembly can be easily connected to an external flow path such as a dialysis circuit or an infusion line. In the invention described in (v) above, by inserting and fixing the base end portion of the outer needle into the large-diameter cylindrical portion of the tube, it becomes easier to make the inner diameter dimension of the tube at the connection portion between the outer needle and the tube equal to or smaller than the inner diameter dimension of the outer needle. The invention described in (vi) above can prevent a sudden expansion of the inner diameter at the connection portion between the outer needle and the flow path forming member, while preventing the flow path forming member from becoming thicker than necessary on the base end side of the connection portion with the outer needle. In the invention described in (vii) above, a sudden increase in the inner diameter from the tip of the outer needle to the base end of the tube is avoided. This prevents a sudden change in volume in the internal space of the outer needle assembly, thereby preventing air from being drawn in or stagnating in the area of ​​such a sudden change in volume. The stepped portion with an increased diameter is a portion where the cross-sectional area of ​​the flow path changes suddenly, and includes, for example, a step surface that expands in the direction perpendicular to the axis. The same effect can be achieved in a needle assembly having a single needle, as in the invention described above in (viii), and the effect of preventing air from remaining in the lumen of the needle assembly having the needle can be achieved. Note that this aspect can be understood to be feasible by using the needle of this aspect as the outer needle (48) in the embodiments described below. [Explanation of symbols]

[0096] 10 Outer needle assembly (first embodiment) 12 Indwelling needle assembly 14 Inner needle assembly 16 Inner needle 18 Blade surface 20 needle tip 22 Inner needle hub 24 Base 26 Protector housing 28 Connecting part 30 Regulating tube 32 Inner needle cap 33 Membrane filter 34 Protector housing 36 Storage tube 38 Lid 40 Needle tip protector 42 Shielding member 44 Fixing member 46 Lumen (internal space) 48 Outer needle 50 outer needle hub (flow path forming member) 51 Proximal part 52 Part 1 54 Part 2 55 Tip part 56 Puncture site 57 Tapered section 58 Needle joining member 59 Flow path connecting member 60 tubes 62 Valve housing 64 Valve body 66 Pusher 68 Cover member 70 Pusher guide 72 Tube connecting member 73 Tube fixing part 73a Tapered surface 73b Proximal tube part 74 Male thread 76 Cut 77 Valve support member 78 1st interior space 79 Second interior space 80 Ventilation Channel 82 Ventilated filter 84 Large diameter cylinder 86 Step surface 88 Connection part 89 Small diameter section 90 Connector cap 92 Bottom wall 94 Tubular process 96 Circumferential wall 98 Elastic piece 100 female thread 102 Locking protrusion 104 External flow path 106 male connector 110 Outer needle assembly (second embodiment) 112 tubes 114 Small diameter cylinder part 116 Thick-walled joint 120 Outer needle assembly (third embodiment) 122 outer needle hub (flow path forming member) 124 Branch 126 Branching member 132 Branch port section 134 Connection port

Claims

1. a hollow outer needle through which an inner needle is inserted, and a flow path forming member connected to the outer needle; the flow path forming member has a flexible tube and a flow path connecting member, a valve body provided inside the flow path connecting member; an outer needle assembly in which the axial length from the valve body to the tip of the outer needle in a first internal space on the tip side of the valve body is longer than the axial length from the valve body to the base end of the flow path connecting member in a second internal space on the base end side of the valve body, an air passage for releasing air from the first internal space to the outside communicates with the first internal space near the valve body; the first internal space comprises a puncture portion formed at a portion of the outer needle that punctures a blood vessel, a tapered portion formed proximal to the puncture portion and having an inner diameter that increases toward the proximal end, and a small-diameter portion formed proximal to the tapered portion and having an inner diameter that is smaller than or the same as the inner diameter of the proximal end of the tapered portion and is smaller than the inner diameter of the proximal end of the first internal space, The reduced diameter portion includes a distal end of the first interior space formed by the tube.

2. The outer needle assembly according to claim 1 , wherein the flow path forming member comprises a flexible tube, and the tube is connected to the outer needle.

3. 3. The outer needle assembly according to claim 2, wherein a large-diameter cylindrical portion having an increased inner diameter is provided at the distal end portion of the tube, and the proximal end portion of the outer needle is inserted into and fixed to the large-diameter cylindrical portion.

4. The outer needle assembly according to claim 3, wherein the tube is provided with a small-diameter cylindrical portion closer to the proximal end than the large-diameter cylindrical portion, the small-diameter cylindrical portion having smaller inner and outer diameters than the large-diameter cylindrical portion.

5. The outer needle assembly according to any one of claims 1 to 4, wherein the flow path forming member comprises a flexible tube, and no stepped, enlarged diameter portion is provided on the inner circumferential surface extending from the tip of the outer needle to the base end of the tube.

6. a flow path forming member connected to the needle; the flow path forming member has a flexible tube and a flow path connecting member, a valve body provided inside the flow path connecting member; a needle assembly in which an axial length from the valve body to the tip of the needle in a first internal space on the tip side of the valve body is longer than an axial length from the valve body to a base end of the flow path connecting member in a second internal space on the base end side of the valve body, an air passage for releasing air from the first internal space to the outside communicates with the first internal space near the valve body; the first internal space comprises a puncture portion formed at a portion of the needle that punctures a blood vessel, a tapered portion formed proximal to the puncture portion and having an inner diameter that increases toward the proximal end, and a small-diameter portion formed proximal to the tapered portion and having an inner diameter that is smaller than or equal to the inner diameter of the proximal end of the tapered portion and is smaller than the inner diameter of the proximal end of the first internal space; The reduced diameter portion includes a distal end of the first interior space defined by the tube.

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