Medical catheter

Abstract

A connector (10) is provided at one end of a tube (90). A through hole (20) penetrates the connector so as to connect a first end (11) and a second end (12) of the connector. The connector is provided with a connection part (30) on the first end side and a tube insertion part (40) on the second end side. The tube insertion part is provided with a fixing part (41) in which the tube is fixed to the connector with the fixing layer (80) interposed therebetween, and a separation part (42) disposed on the second end side with respect to the fixing part. In the separation part, the inner peripheral surface of the through-hole is radially separated from an outer peripheral surface (95) of the tube. A fixing layer end (81), which is an end on the second end side of the fixing layer, is separated from the second end on the first end side along a shaft (19) of the connector.

Description

Medical Catheters

[0001] The present invention relates to a medical catheter having a tube with a connector at one end.

[0002] Enteral nutrition is known as a method for administering liquids, including nutrients and medications, to patients who are no longer able to take food orally. In enteral nutrition, a catheter is inserted into the patient from outside the body until its tip reaches the digestive tract (e.g., the stomach) and remains in the patient. Known catheters include nasal (or oral) catheters inserted through the patient's nose (or mouth) and PEG (Percutaneous Endoscopic Gastrostomy) catheters inserted into a gastrostomy fistula formed in the patient's abdomen. A catheter includes a flexible, hollow tube and a connector attached to one end (the upstream or proximal end) of the tube (see, for example, FIG. 2 of Patent Document 1).

[0003] When performing enteral nutrition, a catheter is inserted into a patient and another connector (a mating connector) is connected to the connector of the catheter (a patient-side connector). When connecting the mating connector to the patient-side connector, a procedure (hereinafter referred to as a "tube bending procedure") is sometimes performed to bend the tube connected to the patient-side connector to block the flow path in order to prevent the patient's stomach contents from refluxing and leaking out of the patient-side connector. In the tube bending procedure, the tube is often bent at a substantially right angle or more to the axis of the connector at the proximal end of the patient-side connector from which the tube is led (e.g., so that the tube becomes substantially "U" shaped).

[0004] JP 2021-159129 A JP 2023-056709 A

[0005] Generally, a connector is fixed to a tube via an adhesive (see, for example, FIG. 4 of Patent Document 2). When a tube is bent, stress is concentrated in a portion near the axial end of the adhesive (hereinafter referred to as the "portion near the end").

[0006] Catheters are left in patients for long periods of time. During this time, if the above-mentioned tube bending procedure is performed each time enteral nutrition is administered, the portion near the end is repeatedly subjected to stress. As a result, the tube may separate from the connector starting from the portion near the end, or the tube may be damaged near the end (e.g., perforated or broken). In such cases, the catheter must be replaced with a new one, which hinders the smooth implementation of enteral nutrition.

[0007] The present invention aims to prevent separation of the tube from the connector starting from a portion near the end or damage to the tube near the end due to a tube bending procedure in which the tube is bent at the base end of the connector.

[0008] The medical catheter of the present invention comprises a flexible, hollow tube and a connector provided at one end of the tube. A through-hole penetrates the connector along the axis of the connector to connect the first and second ends of the connector. The connector has a connection portion at the first end that is connected to a mating connector, and a tube insertion portion at the second end, in which the tube is inserted into the through-hole. The tube insertion portion comprises a fastening portion where the tube is fastened to the connector via a fastening layer, and a separation portion located on the second end side of the fastening portion. In the separation portion, the inner circumferential surface of the through-hole is radially separated from the outer circumferential surface of the tube. The fastening layer end, which is the end of the fastening layer on the second end side, is separated from the second end toward the first end along the axis of the connector.

[0009] In the medical catheter of the present invention, the end of the fixation layer on the second end side of the fixation layer is spaced from the second end toward the first end of the connector. Therefore, even if the tube bending procedure is repeatedly performed over an extended period of time while the catheter is indwelled in a patient, the tube can be prevented from separating from the connector starting from the portion near the fixation layer end (the portion near the end) or from being damaged in the portion near the end. Therefore, the catheter of the present invention has excellent durability against the tube bending procedure.

[0010] FIG. 1A is a perspective view of a medical catheter according to a first embodiment of the present invention. FIG. 1B is a cross-sectional view of the medical catheter shown in FIG. 1A. FIG. 1C is an enlarged cross-sectional view of portion 1C of FIG. 1B. FIG. 2 is a cross-sectional view of a connector according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a method for manufacturing a medical catheter according to the first embodiment of the present invention. FIG. 4 is a cross-sectional view of a medical catheter according to a comparative embodiment. FIG. 5 is a cross-sectional view of a medical catheter according to a comparative embodiment when a tube bending procedure has been performed. FIG. 6 is a cross-sectional view of a medical catheter according to the first embodiment of the present invention when a tube bending procedure has been performed. FIG. 7 is an enlarged cross-sectional view of a first modified example of the medical catheter according to the first embodiment of the present invention. FIG. 8 is an enlarged cross-sectional view of a second modified example of the medical catheter according to the first embodiment of the present invention. FIG. 9 is an enlarged cross-sectional view of a third modified example of the medical catheter according to the first embodiment of the present invention. FIG. 10 is a cross-sectional view of a medical catheter according to a second embodiment of the present invention. FIG. 11 is a cross-sectional view illustrating a method for manufacturing a medical catheter according to the second embodiment of the present invention.

[0011] (1) A medical catheter of the present invention comprises a flexible, hollow tube and a connector provided at one end of the tube. A through-hole penetrates the connector along the axis of the connector to connect a first end and a second end of the connector. The connector comprises a connection portion at the first end to be connected to a mating connector, and a tube insertion portion at the second end, in which the tube is inserted into the through-hole. The tube insertion portion comprises a fastening portion where the tube is fastened to the connector via a fastening layer, and a separation portion located on the second end side of the fastening portion. In the separation portion, the inner circumferential surface of the through-hole is radially separated from the outer circumferential surface of the tube. The fastening layer end, which is the end of the fastening layer on the second end side, is separated from the second end toward the first end along the axis of the connector.

[0012] (2) In the medical catheter of the above item (1), the length L along the axis of the connector from the second end to the end of the fixing layer may be 5 mm or more and 10 mm or less.

[0013] The aspect of item (2) is advantageous in reducing the possibility of the tube separating from the connector starting from the portion near the end of the adhesive layer (the portion near the end) or of the tube breaking in the portion near the end.

[0014] (3) In the medical catheter of (1) or (2) above, when the opening diameter of the through hole at the second end is Dc, the outer diameter of the tube is Dt, and the length along the axis of the connector from the second end to the end of the fixing layer is L, the following relationship may be satisfied: [(Dc-Dt) / 2] / L≦0.10.

[0015] The aspect of (3) is advantageous in reducing the possibility of the tube separating from the connector starting from the portion near the end of the fixing layer (the portion near the end) or of the tube breaking in the portion near the end.

[0016] (4) In the medical catheter according to any one of (1) to (3), when the opening diameter of the through hole at the second end is Dc and the outer diameter of the tube is Dt, the relationship Dc / Dt≦1.30 may be satisfied.

[0017] The aspect of item (4) is advantageous in reducing the possibility of the tube separating from the connector starting from the portion near the end of the adhesive layer (the portion near the end) or of the tube breaking in the portion near the end.

[0018] (5) In the medical catheter according to any one of (1) to (4), the inner circumferential surface of the through-hole in the tube insertion section may include an expanded diameter section. The expanded diameter section may be a curved surface whose inner diameter increases toward the second end. The end of the fixing layer may be located in the expanded diameter section.

[0019] The aspect of item (5) is advantageous in stably preventing separation of the tube from the connector starting from the portion near the end of the fixation layer (portion near the end) when performing a tube bending procedure.

[0020] (6) In the medical catheter according to any one of (1) to (5), the inner circumferential surface of the through hole in the tube insertion section may include a first tapered section, an expanded diameter section, and a cylindrical section, which are arranged adjacent to one another from the first end to the second end. The first tapered section may be a conical surface whose inner diameter increases toward the second end. The expanded diameter section may be a curved surface whose inner diameter increases toward the second end. The cylindrical section may be a cylindrical surface whose inner diameter is constant in the axial direction of the connector. The inner diameter of the cylindrical section may be larger than the outer diameter of the tube. The fixing layer may extend from the first tapered section toward the expanded diameter section. An end of the fixing layer may be located at the expanded diameter section.

[0021] The positioning of the end of the fixation layer in the expanded diameter section is advantageous in reliably preventing the tube from separating from the connector starting from the portion near the end of the fixation layer (the portion near the end) when performing the tube bending procedure.

[0022] The cylindrical portion provided on the second end side of the enlarged diameter portion facilitates reducing the opening diameter Dc at the second end of the through hole, which is advantageous in reducing the possibility of the tube separating from the connector starting from the portion near the end of the fixing layer (the portion near the end) or of the tube breaking near the end.

[0023] (7) In the medical catheter according to any one of (1) to (6), the inner circumferential surface of the through hole may include a first tapered portion and a second tapered portion arranged adjacent to each other from the second end toward the first end. The first tapered portion and the second tapered portion may both be conical surfaces whose inner diameters increase toward the second end. The fixing layer may fix the outer circumferential surface of the tube to the first tapered portion. An outer circumferential surface end, which is the proximal end of the outer circumferential surface of the tube, may abut against the second tapered portion.

[0024] The aspect of item (7) is advantageous in preventing the strength of the attachment of the tube to the connector from being reduced by the sterilization process of the medical catheter.

[0025] (8) In the medical catheter according to any one of (1) to (7), the connecting portion may be a male connector used for enteral nutrition, comprising a cylindrical male member having the through hole, an outer tube surrounding the male member coaxially with the male member, and a female screw provided on the inner surface of the outer tube.

[0026] The medical catheter of item (8) equipped with the male connector can be placed in a patient for enteral nutrition. In enteral nutrition, a tube bending procedure is frequently performed on the catheter while it is placed in the patient. Because the catheter of the present invention has excellent durability against the tube bending procedure, the catheter of item (8) can significantly exhibit the above-mentioned effects of the present invention when used as a catheter placed in a patient for enteral nutrition.

[0027] (9) In the medical catheter according to any one of (1) to (8) above, a side hole that communicates with the through hole and is not parallel to the axis of the connector may be provided in the tube insertion portion.

[0028] The side hole of item (9) can be used to inject adhesive for fixing the tube to the connector in the manufacture of a medical catheter, so the catheter of item (9) is easy to manufacture and advantageous in improving yield.

[0029] The present invention will be described in detail below, illustrating preferred embodiments. However, it goes without saying that the present invention is not limited to the following embodiments. For the sake of convenience, the drawings referred to in the following description show simplified views of the main components constituting the embodiments of the present invention. Therefore, the present invention may include any components not shown in the following drawings. Furthermore, within the scope of the present invention, the components shown in the following drawings may be modified or omitted. In the drawings referred to in the description of each embodiment, components corresponding to components shown in the drawings referred to in the preceding embodiment are designated by the same reference numerals as those in the drawings of the preceding embodiment. Duplicate descriptions of such components are omitted, and the descriptions of the preceding embodiment should be taken into consideration as appropriate.

[0030] In the present invention, the "axis" of a component (e.g., a connector, a connection portion, a tube insertion portion, a through-hole) refers to the central axis of the component. The "axis" passes through the center of a figure (e.g., a circle) included in the component and / or coincides with the central axis of a columnar body (e.g., a column, a cylinder), a cylindrical surface, or a conical surface (taper) included in the component. Unless otherwise specified, the direction parallel to the axis is referred to as the "axial direction." The direction along a straight line perpendicular to the axis is referred to as the "radial direction." In the radial direction, the side closer to the axis is referred to as the "inner" side, and the side farther from the axis is referred to as the "outer" side. The direction of rotation around the axis is referred to as the "circumferential direction." Since a person skilled in the art can easily and unambiguously identify an axis, in many of the drawings cited in the following description, the illustration of the axis is omitted to simplify the drawing.

[0031] In the present invention, the "proximal" side means the side closer to the surgeon (or user), and the "distal" side means the side farther from the surgeon (or user) (see FIG. 1B described below). Here, "surgeon (or user)" refers to a person who uses the medical catheter of the present invention (e.g., a doctor, nurse, caregiver, etc.). In the following description, the axial end (terminal end) of a member may be referred to as the "tip," and the end opposite the "tip" may be referred to as the "base end." The "tip" may be located on either the "proximal" or "distal" side of the "base end."

[0032] (Embodiment 1) Fig. 1A is a perspective view of a medical catheter (hereinafter simply referred to as "catheter") 1 according to Embodiment 1 of the present invention. Fig. 1B is a cross-sectional view of the catheter 1. The catheter 1 comprises a flexible, hollow tube 90 and a connector 10 provided at one end (proximal end) of the tube 90. The catheter 1 can be used as a nasal catheter.

[0033] Figure 2 is a cross-sectional view of the connector 10. The connector 10 has a first end 11 at one end (proximal end, upper end in Figure 2) in the longitudinal direction of the connector 10, and a second end 12 at the other end (distal end, lower end in Figure 2). An axis 19 of the connector 10 connects the first end 11 and the second end 12. A through-hole 20 penetrates the connector 10 along the axis 19 of the connector 10 so as to connect the first end 11 and the second end 12 of the connector 10.

[0034] The connector 10 includes a connecting portion 30 at the first end 11, which is connected to a connector (a mating connector, not shown) separate from the connector 10. The present invention does not limit the configuration of the connecting portion 30. The connecting portion 30 of this embodiment 1 includes a cylindrical male member 31 and an outer tube 35 coaxially surrounding the male member 31. A female thread 36 is provided on the inner circumferential surface of the outer tube 35 facing the male member 31. A through hole 20 penetrates the male member 31 and opens at the tip of the male member 31 (i.e., the first end 11 of the connector 10). The outer circumferential surface 32 of the male member 31 is a tapered surface (a so-called male taper surface) whose outer diameter decreases toward the tip of the male member 31. The inner circumferential surface 33 of the male member 31 (the inner circumferential surface of the male member 31 in the through hole 20) is not limited and may be composed of a single curved surface or multiple curved surfaces adjacent to each other in the axial direction 19. In the first embodiment, the inner peripheral surface 33 is composed of a plurality of tapered surfaces adjacent to each other in the axial direction. Each of the plurality of tapered surfaces is a tapered surface (conical surface) whose inner diameter increases toward the tip (first end 11) of the male member 31, and the plurality of tapered surfaces have different inner diameters and taper angles. However, in the present invention, the inner peripheral surface 33 is not limited to this and may include, for example, a cylindrical surface whose inner diameter is constant in the axial direction or any curved surface whose inner diameter changes nonlinearly in the axial direction.

[0035] As shown in FIG. 1A , the connector 10 has a substantially cylindrical base tube 50 on the second end 12 side. The base tube 50 is arranged coaxially with the male member 31. A pair of grip portions 52 protrude radially outward from the base tube 50. The grip portions 52 facilitate an operator's grip of the connector 10 and application of a rotational force to the connector 10. In the present invention, the configuration of the second end 12 side of the connector 10 is not limited to that of the first embodiment. For example, the connector 10 may not include the pair of grip portions 52. Alternatively, instead of the pair of grip portions 52, a pair of plate-like bodies protruding in opposite directions along the radial direction may be provided on the outer peripheral surface of the base tube 50. The shape of the base tube 50 is not limited to a substantially cylindrical shape. For example, the outer peripheral surface of the base tube 50 may have a quadrangular prism surface whose cross section along a plane perpendicular to the axis of the connector 10 is rectangular. The pair of plate-like bodies and the outer peripheral surface of the base tube having a rectangular prism surface, like the pair of grip portions 52, make it easy for the surgeon to grip the connector 10 and apply a rotational force.

[0036] Returning to FIG. 2, the through-hole 20 passes through the base tube 50 and opens at the tip of the base tube 50 (i.e., the second end 12 of the connector 10).

[0037] The inner diameter of the through hole 20 varies in the axial direction of the connector 10. In the first embodiment, the inner circumferential surface of the through hole 20 includes a plurality of portions (sections) with different shapes. Specifically, the inner circumferential surface of the through hole 20 includes, from the first end 11 to the second end 12, a second tapered portion 22, a first tapered portion 21, an expanded diameter portion 23, and a cylindrical portion 25.

[0038] The second tapered portion 22 is disposed on the second end 12 side with respect to the inner peripheral surface 33 of the male member 31. The second tapered portion 22 is configured as a tapered surface (a conical surface, a so-called female tapered surface) whose inner diameter increases toward the second end 12.

[0039] The first tapered portion 21 is disposed on the second end 12 side of the second tapered portion 22 and is adjacent to the second tapered portion 22. The first tapered portion 21 is configured with a tapered surface (a conical surface, a so-called female tapered surface) whose inner diameter increases toward the second end 12. The taper angle of the tapered surface of the first tapered portion 21 is smaller than the taper angle of the tapered surface of the second tapered portion 22. The minimum inner diameter of the first tapered portion 21 (the inner diameter of the first tapered portion 21 at the end of the first end 11) is equal to the maximum inner diameter of the second tapered portion 22 (the inner diameter of the second tapered portion 22 at the end of the second end 12).

[0040] The expanded diameter portion 23 is disposed on the second end 12 side of the first tapered portion 21 and is adjacent to the first tapered portion 21. The expanded diameter portion 23 is configured with a curved surface whose inner diameter increases toward the second end 12. In the first embodiment, the curved surface of the expanded diameter portion 23 is configured with a tapered surface (a conical surface, a so-called female tapered surface) whose inner diameter increases toward the second end 12. The taper angle of the tapered surface of the expanded diameter portion 23 is larger than the taper angle of the tapered surface of the first tapered portion 21. The minimum inner diameter of the expanded diameter portion 23 (the inner diameter of the expanded diameter portion 23 at the end of the first end 11) is equal to the maximum inner diameter of the first tapered portion 21 (the inner diameter of the first tapered portion 21 at the end of the first tapered portion 21 at the second end 12).

[0041] The cylindrical portion 25 is disposed on the second end 12 side of the expanded diameter portion 23 and is adjacent to the expanded diameter portion 23. The cylindrical portion 25 is configured with a cylindrical surface whose inner diameter is constant in the axial direction (the longitudinal direction of the through hole 20). The inner diameter of the cylindrical portion 25 is the same as the maximum inner diameter of the expanded diameter portion 23 (the inner diameter of the expanded diameter portion 23 at the end of the second end 12). The through hole 20 opens at the end of the cylindrical portion 25 on the second end 12 side. The end of the cylindrical portion 25 on the second end 12 side is substantially in the same position as the second end 12 of the connector 10 in the axial direction.

[0042] The material of the connector 10 is not limited, but may be a hard material (rigid material) that has sufficient mechanical strength (rigidity) to prevent substantial deformation due to external forces. Examples of resin materials that may be used include acrylic resin, polycarbonate, rigid polyvinyl chloride, polypropylene, polyethylene, acrylonitrile-butadiene-styrene copolymer, polyacetal, polystyrene, and polyamide. One example is acrylic resin. The connector 10 can be manufactured as a single component using the above resin materials by injection molding or other methods.

[0043] As shown in FIG. 1B, the tube 90 is inserted into the through-hole 20 from the second end 12 side.

[0044] The tube 90 has a hollow cylindrical shape. In a cross section of the tube 90 taken along a plane perpendicular to the longitudinal direction of the tube 90, the outer and inner peripheral surfaces of the tube 90 form concentric circles. The outer and inner diameters of the tube 90 are constant in the longitudinal direction of the tube 90, excluding variations due to manufacturing errors. The material of the tube 90 is not limited, but flexible resins such as soft polyvinyl chloride, polybutadiene, silicone, polyurethane, polypropylene, polyethylene, polybutadiene, and styrene-based elastomers can be used. The tube 90 can be continuously manufactured using the above materials, for example, by extrusion molding. The tube 90 can be relatively easily curved and radially compressed by applying an external force, and then returns to its initial state when the external force is removed.

[0045] The inner diameter of the cylindrical portion 25 (which is the same as the maximum inner diameter of the expanded diameter portion 23) is larger than the outer diameter of the tube 90, even considering manufacturing errors of the tube 90 (or variations in the outer diameter of the tube 90). Furthermore, the minimum inner diameter of the second tapered portion 22 (the inner diameter of the second tapered portion 22 at the end of the second tapered portion 22 near the first end 11) is smaller than the outer diameter of the tube 90, even considering manufacturing errors of the tube 90 (or variations in the outer diameter of the tube 90). The minimum inner diameter of the expanded diameter portion 23 (which is the same as the maximum inner diameter of the first tapered portion 21) and the minimum inner diameter of the first tapered portion 21 (which is the same as the maximum inner diameter of the second tapered portion 22) are approximately the same as the outer diameter of the tube 90 (they may be slightly larger or slightly smaller than the outer diameter of the tube 90). Note that, in the above, the "outer diameter" of the tube 90 refers to the outer diameter of the tube 90 in a state where no external force is applied to the tube 90 (in an unloaded state or initial state) before it is inserted into the through-hole 20 of the connector 10.

[0046] The tube 90 is inserted until an outer peripheral surface end 91, which is the proximal end of the outer peripheral surface 95 of the tube 90, abuts against the inner peripheral surface of the second tapered portion 22. In the present invention, the portion of the connector 10 into which the tube 90 is inserted is referred to as the tube insertion portion 40. More specifically, the tube insertion portion 40 extends in the axial direction from the second end 12 of the connector 10 to the outer peripheral surface end 91 (or the proximal end) of the tube 90. In the first embodiment, the tube insertion portion 40 includes the cylindrical portion 25, the expanded diameter portion 23, and the first tapered portion 21, and may further include a portion of the second tapered portion 22 on the first tapered portion 21 side.

[0047] The tube 90 is fixed to the connector 10 via a fixing layer 80. The fixing layer 80 is present between the connector 10 (the inner peripheral surface of the through hole 20) and an outer peripheral surface 95 of the tube 90, and is continuous in the circumferential direction so as to surround the tube 90. The fixing layer 80 is present only in a portion of the tube insertion portion 40 in the axial direction. As shown in FIG. 1C, which is an enlarged cross-sectional view of portion 1C of FIG. 1B, the tube insertion portion 40 has a fixing portion 41 where the tube 90 is fixed to the connector 10 via the fixing layer 80, and a spaced portion 42 located on the second end 12 side of the fixing portion 41 and adjacent to the fixing portion 41. The fixing layer 80 is not present in the spaced portion 42. More specifically, in the spaced portion 42, the outer peripheral surface 95 of the tube 90 is not fixed to the inner peripheral surface of the through hole 20, and the inner peripheral surface of the through hole 20 is radially spaced from the outer peripheral surface 95 of the tube 90. Therefore, when a radially outward force is applied to the portion of the tube 90 extending from the connector 10, the tube 90 can move radially in the separation section 42. The fastening layer end 81, which is the end (terminal end) of the fastening layer 80 on the second end 12 side (the separation section 42 side), is spaced from the second end 12 (the tip of the base tube 50 or the open end of the through hole 20 on the second end 12 side) toward the first end 11 along the axis of the connector 10. In the first embodiment, the fastening layer end 81 is located in the expanded diameter section 23. The fastening layer 80 extends from the fastening layer end 81 toward the first end 11, preferably to the outer peripheral surface end 91 of the tube 90. Therefore, the fastening layer 80 is present in part of the expanded diameter section 23 and the first tapered section 21 of the tube insertion section 40, and may also be present in part of the second tapered section 22.

[0048] The fixing layer 80 may have any configuration capable of fixing (connecting) the tube 90 to the connector 10. The method for fixing the tube 90 to the connector 10 can be selected depending on the materials of the connector 10 and the tube 90, and is not limited to, for example, a method using an adhesive (adhesion method) or a welding method (welding method). Examples of adhesives that can be used in the adhesion method include solvent-based adhesives, UV adhesives, and instant adhesives. When the adhesion method is used, the fixing layer 80 is an adhesive layer resulting from the adhesive. Examples of welding methods include, but are not limited to, laser welding and high-frequency welding. When the welding method is used, the fixing layer 80 is a welded layer formed by melting and solidifying both the materials of the tube 90 and the connector 10.

[0049] An example of a method for manufacturing the catheter 1 will be described using a solvent-based adhesive.

[0050] First, the connector 10 and the tube 90 are prepared. As shown in FIG. 3 , the connector 10 is held with a jig or the like (not shown) with the second end 12 facing up and the axis of the connector 10 parallel to the vertical direction. The outer diameter of the tube 90 is smaller than the inner diameter of the cylindrical portion 25 and larger than the minimum inner diameter of the second tapered portion 22. The tube 90 is cut to a predetermined length. The cut surface on the proximal side of the tube 90 is referred to as the proximal end surface 92. The proximal end surface 92 is a substantially flat surface and is approximately perpendicular to the longitudinal direction of the tube 90. The boundary between the outer peripheral surface 95 and the proximal end surface 92 of the tube 90 is the outer peripheral surface end 91. A solvent-based adhesive 85 is applied to the outer peripheral surface 95 of the tube 90 over a predetermined length from the outer peripheral surface end 91. The proximal end surface 92 of the tube 90 is coaxially opposed to the opening on the second end 12 side of the through-hole 20 of the connector 10. The tube 90 is then inserted into the through hole 20. Because the tube 90 has a smaller diameter than the cylindrical portion 25, it can be inserted into the through hole 20 relatively easily. The tube 90 then enters the first tapered portion 21. Any excess solvent-based adhesive 85 on the outer circumferential surface 95 may be scraped off at the end of the first tapered portion 21 near the second end 12 and remain in the expanded diameter portion 23. In the first tapered portion 21, the solvent-based adhesive 85 spreads thinly and approximately uniformly in the narrow gap between the outer circumferential surface 95 of the tube 90 and the inner circumferential surface of the first tapered portion 21. The tube 90 is inserted into the through hole 20 until the outer circumferential surface end 91 abuts the inner circumferential surface of the second tapered portion 22. The second tapered portion 22 can determine the insertion depth of the tube 90 into the through hole 20. The solvent-based adhesive 85 dissolves the outer circumferential surface 95 of the tube 90 and the inner circumferential surface of the through-hole 20 (particularly the first tapered portion 21) that it comes into contact with, and solidifies as the solvent evaporates, forming an adhesive layer 80 (see FIG. 1C ). The connector 10 and the tube 90 are then sterilized. Thus, the catheter 1 shown in FIGS. 1A to 1C is obtained, in which the connector 10 is fixed to the tube 90 via the adhesive layer 80. While the manufacturing method shown in FIG. 3 holds the connector 10 with the second end 12 facing up, the orientation of the connector 10 is not limited thereto. For example, the connector 10 may be held with its axis oriented horizontally, or with its first end 11 facing up.Alternatively, the tube 90 may be held in a predetermined orientation instead of the connector 10 , and the connector 10 may be fitted onto the tube 90 .

[0051] As described above, the solvent-based adhesive 85 generally contains an organic solvent and can dissolve both the surfaces of the connector 10 and the tube 90 that come into contact with the solvent-based adhesive 85. Therefore, when using the solvent-based adhesive 85 as the adhesive, the inner diameter of the through hole 20 and the outer diameter of the tube 90 (outer diameter in an unloaded state) before assembly are preferably set taking into account the thickness to be dissolved by the solvent-based adhesive 85. Specifically, the minimum inner diameter of the expanded diameter portion 23 (which is the same as the maximum inner diameter of the first tapered portion 21) and the minimum inner diameter of the first tapered portion 21 (which is the same as the maximum inner diameter of the second tapered portion 22) are preferably slightly smaller than the outer diameter of the tube 90 (outer diameter in an unloaded state). This prevents air bubbles from being mixed into the bonded layer 80 obtained by solidifying the solvent-based adhesive 85, which is advantageous for improving the bond strength of the tube 90 to the connector 10.

[0052] The catheter 1 (see FIGS. 1A to 1C ) can be used, for example, as a nasal catheter for enteral nutrition, without limitation. In this case, the tube 90 is inserted through the patient's nasal cavity. Once the distal end of the tube 90 (or the tip of the tube 90, not shown in FIGS. 1A and 1B ) reaches the patient's digestive tract (e.g., the stomach), and the connector 10 is attached to the proximal end of the tube 90 leading out of the patient, the catheter 1 is left indwelling in the patient for an extended period of time. When performing enteral nutrition, a connector (a mating connector) separate from the connector 10 is connected to the connection portion 30 of the connector 10. The mating connector may be attached to the end of a tube communicating with a container containing a liquid to be administered to the patient, or may be attached to the tip of a syringe. Alternatively, the tip of the syringe may be the mating connector. With the mating connector connected to the connector 10, the liquid is administered to the patient through the mating connector, the connector 10, and the tube 90, in that order.

[0053] The effects of the catheter 1 of this embodiment 1 will be explained in comparison with a comparative embodiment which is a conventional general catheter.

[0054] FIG. 4 is a cross-sectional view of a medical catheter 9 according to a comparative embodiment. The catheter 9 includes a flexible, hollow tube 90 and a connector 910 provided at one end (proximal end) of the tube 90. A through-hole 20 penetrates the connector 910 along its axis (not shown) to connect the first end 11 and second end 12 of the connector 910. The inner circumferential surface of the through-hole 20 includes, from the first end 11 to the second end 12, a small-diameter portion 927, a stepped portion 922, a cylindrical portion 921, and a tapered portion 925. The cylindrical portion 921 is configured as a cylindrical surface whose inner diameter is constant in the axial direction (the longitudinal direction of the through-hole 20). The tapered portion 925 is positioned closer to the second end 12 than the cylindrical portion 921 and is adjacent to the cylindrical portion 921. The tapered portion 925 is configured as a tapered surface (a conical surface, a so-called female tapered surface) whose inner diameter increases toward the second end 12. The reduced diameter portion 927 is configured as a cylindrical surface or a tapered surface having a smaller diameter than the cylindrical portion 921. The stepped portion 922 is disposed between the reduced diameter portion 927 and the cylindrical portion 921 and is configured as an annular flat surface perpendicular to the axis of the connector 910. The proximal end surface 92 of the tube 90 faces the stepped portion 922 in the axial direction. The tube 90 is fixed to the connector 910 via an adhesive layer 980. The adhesive layer 980 extends over the stepped portion 922, the cylindrical portion 921, and the tapered portion 925. More specifically, the adhesive layer 980 exists between the annular flat surface of the stepped portion 922 and the proximal end surface 92 of the tube 90. The adhesive layer 980 also exists between the inner circumferential surfaces of the cylindrical portion 921 and the tapered portion 925 and the outer circumferential surface 95 of the tube 90. Furthermore, the fixation layer 980 bulges axially in a dome shape from the second end 12 of the connector 910. The configuration of the fixation layer 980 and its vicinity is common in conventional catheters, and is shown in Figure 6 of Patent Document 2, for example.

[0055] The catheter 9 does not have a portion corresponding to the separation portion 42 of the catheter 1 of the present embodiment 1. The fixation layer end 981, which is the end (terminal end) of the fixation layer 980 on the second end 12 side, is spaced from the second end 12 along the axis of the connector 910 on the side opposite to the first end 11.

[0056] Like catheter 1, catheter 9 can be used as a nasal catheter for enteral nutrition. When performing enteral nutrition, a connector (a mating connector) other than connector 910 is connected to connection portion 30 of connector 910 while tube 90 is inserted into a patient. When connecting the mating connector to connector 910, a "tube bending procedure" may be performed in which tube 90 is bent to block the flow path in order to prevent the contents of the patient's stomach from refluxing and leaking out of first end 11 of connector 910.

[0057] FIG. 5 is a cross-sectional view of the catheter 9 when a tube bending procedure is performed. To easily and reliably close the flow path of the tube 90, the tube 90 is often bent at a substantially right angle (or greater than a right angle) relative to the axis of the connector 910 (not shown) using the fixation layer end 981 as a fulcrum during the tube bending procedure. To bend the tube 90 in this manner, a tension force T must be applied to the tube 90 in a substantially radially outward direction (toward the right in FIG. 5 ) relative to the axis of the connector 910. As a result, stress is concentrated in a portion (near the end portion) 982 near the fixation layer end 981 on the side opposite the direction of the tension force T (to the left in FIG. 5 ). This stress acts on the end portion 982 along the bent tube 90, i.e., in the direction of the tension force T (toward the right in FIG. 5 ). This stress has the effect of separating the tube 90 from the adhesive layer 980 in a direction approximately perpendicular to the axis of the connector 910 (to the right in Figure 5) in the end-nearby portion 982, and also has the effect of locally bending and deforming the tube 90 approximately at a right angle in the end-nearby portion 982.

[0058] Over the long period that the catheter 9 is indwelled in the patient, the end vicinity portion 982 is repeatedly subjected to the above-mentioned stress due to the tube bending procedure that is performed each time enteral nutrition is performed. As a result, the tube 90 may separate from the fixation layer 980 starting from the end vicinity portion 982, and eventually the tube 90 may fall off the connector 910 or the tube 90 may be damaged at the end vicinity portion 982 (e.g., holes or breakage of the tube 90). In such cases, it becomes necessary to replace the catheter 9 with a new one before the expected period for which the catheter 9 will be indwelled in the patient (expected indwelling period) has expired, which hinders the smooth implementation of enteral nutrition.

[0059] FIG. 6 is a cross-sectional view of the catheter 1 according to the first embodiment when a tube bending procedure is performed. During the tube bending procedure, similar to FIG. 5 , a tension T is applied to the tube 90 in a radially outward direction (to the right in FIG. 6 ) relative to the axis of the connector 10. As a result, the tube 90 is bent at a substantially right angle to the axis (not shown) of the connector 10, with the second end 12 as a fulcrum, and the flow path of the tube 90 is blocked. However, in the first embodiment (see FIG. 6 ), unlike the comparative embodiment ( FIG. 5 ), the fixation layer end 81 is located closer to the first end 11 than the second end 12. Therefore, within the range from the second end 12 to the fixation layer end 81, the tube 90 is slightly tilted in the direction of the tension T relative to the axis of the connector 10 within the through-hole 20. As in FIG. 5 , in FIG. 6 , stress is concentrated in a portion 82 (near the end portion) near the fixation layer end 81 on the side opposite the direction of the tension T (left side in FIG. 6 ). However, unlike the comparative embodiment (see FIG. 5 ), in the present embodiment 1 ( FIG. 6 ), the inclination of the tube 90 relative to the axis of the connector 10 is small in the end vicinity 82. The stress is along the direction of this inclination of the tube 90 in the end vicinity 82, regardless of the direction of the tension T (to the right in FIG. 6 ). Therefore, in the present embodiment 1, the action of the stress attempting to separate the tube 90 from the connector 10 (the inner circumferential surface of the through-hole 20) is smaller than in the comparative embodiment (see FIG. 5 ). Furthermore, the angle (bending angle) at which the stress bends and deforms the tube 90 in the end vicinity 82 is smaller than the bending angle of the tube 90 in the end vicinity 982 of the comparative embodiment (see FIG. 5 ).

[0060] As described above, in the first embodiment, the fixation layer end 81 is spaced from the second end 12 toward the first end 11 along the axis 19 of the connector 10 (i.e., the fixation layer end 81 is recessed into the through-hole 20). Therefore, when a tube bending procedure is performed to bend the tube 90 at the second end 12 of the connector 10, first, the stress generated in the portion 82 near the fixation layer end 81 (the end vicinity portion) has a weak effect of separating the tube 90 from the connector 10 (the inner peripheral surface of the through-hole 20), and second, the bending angle of the tube 90 at the end vicinity portion 82 is small. As a result, even if the tube bending procedure is repeatedly performed over a long period of time while the catheter 1 is indwelled in a patient, the first embodiment can prevent the tube 90 from separating from the connector 10 starting from the end vicinity portion 82 and eventually falling off the connector 10, or from being damaged at the end vicinity portion 82 (e.g., hole formation or breakage of the tube 90). According to this embodiment 1, the catheter 1 can be left in the patient until the expected placement period expires, which is advantageous for smoothly implementing enteral nutrition and preventing an increase in the burden on the patient due to reinsertion of the catheter 1.

[0061] In the present invention, there is no limit to the length L (see FIG. 1C ) along the axis 19 of the connector 10 from the second end 12 to the fixing layer end 81. However, as can be easily understood from FIG. 6 , the longer the length L, the smaller the inclination (bending angle) of the tube 90 relative to the axis of the connector 10 at the end-nearby portion 82 during the tube bending procedure. This is advantageous for reducing the possibility of the tube 90 separating from the connector 10 starting from the end-nearby portion 82 or of the tube 90 breaking at the end-nearby portion 82. From this perspective, a long length L is preferable; specifically, length L is preferably 5 mm or more, more preferably 6 mm or more, and particularly preferably 7 mm or more. However, a longer length L may result in problems such as an increase in the overall axial length of the connector 10 and increased difficulty in the process of adhesively fixing the tube 90 to the connector 10 (see FIG. 3 ). For this reason, length L is preferably 10 mm or less, more preferably 9 mm or less, and particularly preferably 8 mm or less.

[0062] Furthermore, when the opening diameter at the second end 12 of the through hole 20 is Dc, the outer diameter (outer diameter in an unloaded state) of the tube 90 is Dt, and the length along the axis 19 of the connector 10 from the second end 12 to the fixing layer end 81 is L (see Figure 1C), it is preferable to satisfy [(Dc - Dt) / 2] / L≦0.10, and furthermore, [(Dc - Dt) / 2] / L≦0.095.

[0063] Furthermore, it is preferable that the opening diameter Dc at the second end 12 of the through hole 20 and the outer diameter Dt of the tube 90 (outer diameter in an unloaded state) satisfy Dc / Dt≦1.30, or even Dc / Dt≦1.28, and especially Dc / Dt≦1.25.

[0064] The smaller both [(Dc-Dt) / 2] / L and Dc / Dt are, the smaller the inclination (bending angle, see FIG. 6 ) of the tube 90 relative to the axis of the connector 10 at the end vicinity 82 when the tube bending procedure is performed. This is advantageous in reducing the possibility of the tube 90 separating from the connector 10 starting from the end vicinity 82 or of the tube 90 breaking at the end vicinity 82.

[0065] However, if both [(Dc - Dt) / 2] / L and Dc / Dt become small, the process of adhesively attaching the tube 90 to the connector 10 (see FIG. 3) becomes more difficult. Therefore, it is preferable to satisfy [(Dc - Dt) / 2] / L ≥ 0.020, and furthermore, [(Dc - Dt) / 2] / L ≥ 0.030.

[0066] It is also preferable that Dc / Dt≧1.01, and more preferably Dc / Dt≧1.02 be satisfied.

[0067] In the first embodiment, the inner circumferential surface of the through hole 20 in the tube insertion portion 40 includes a first tapered portion 21, an expanded diameter portion 23, and a cylindrical portion 25, which are arranged adjacent to each other from the first end 11 to the second end 12. The fixing layer 80 extends from the first tapered portion 21 toward the expanded diameter portion 23 and terminates at a fixing layer end 81. The fixing layer end 81 is located at the expanded diameter portion 23.

[0068] Unlike the first embodiment, consider a case where the expanded diameter portion 23 is omitted and the cylindrical portion 25 is axially adjacent to the first tapered portion 21 (hereinafter referred to as the "comparative example"). In this comparative example, the inner diameter of the through hole 20 changes abruptly between the first tapered portion 21 and the cylindrical portion 25. When the fixing layer end 81 is located near the boundary between the first tapered portion 21 and the cylindrical portion 25, the thickness (radial dimension) of the fixing layer 80 at the fixing layer end 81 changes abruptly due to a slight difference in the axial position of the fixing layer end 81. The thickness of the fixing layer 80 affects the fixing strength of the tube 90 to the connector 10. Therefore, when tension T is applied to the tube 90 by a tube bending procedure, the effect of the fixing layer 80 in the portion 82 near the fixing layer end 81 (the portion near the end) on preventing the tube 90 from separating from the connector 10 (the inner circumferential surface of the through hole 20) is likely to become unstable.

[0069] In contrast, in the first embodiment, the thickness (radial dimension) of the fixation layer 80 gradually increases from the first tapered portion 21 toward the second end 12 in the expanded diameter portion 23. The fixation layer end 81 is disposed in the expanded diameter portion 23 where the thickness of the fixation layer 80 gradually increases toward the second end 12. Even if the axial position of the fixation layer end 81 changes within the expanded diameter portion 23 due to manufacturing errors or the like, the change in the thickness of the fixation layer 80 is relatively small, and therefore the change in the fixation strength of the tube 90 to the connector 10 in the portion 82 near the fixation layer end 81 is also small. This is advantageous for reliably preventing separation of the tube 90 from the connector 10 starting from the end vicinity 82 when a tube bending procedure is performed.

[0070] In the present invention, the inner circumferential surface of the through-hole 20 in the tube insertion portion 40 is not limited to the first embodiment.

[0071] FIG. 7 is an enlarged cross-sectional view of a medical catheter 1a according to a first modification. Similar to the enlarged diameter portion 23 of the connector 10 (see FIG. 1C), the enlarged diameter portion 23a of the connector 10 is configured as a curved surface whose inner diameter increases toward the second end 12. However, unlike the inner diameter of the enlarged diameter portion 23, the inner diameter of the enlarged diameter portion 23a varies nonlinearly in the axial direction. More specifically, the cross-sectional shape of the enlarged diameter portion 23a along a plane including the axis of the connector 10a is a substantially circular arc that protrudes toward the tube 90. This substantially circular arc connects the first tapered portion 21 and the cylindrical portion 25. The fixing layer end 81 of the fixing layer 80 is located at the enlarged diameter portion 23a. The catheter 1a is identical to the catheter 1 except for the above.

[0072] FIG. 8 is an enlarged cross-sectional view of a medical catheter 1b according to a second modification. Similar to the enlarged diameter portion 23 of the connector 10 (see FIG. 1C), the enlarged diameter portion 23b of the connector 10 is configured as a curved surface whose inner diameter increases toward the second end 12. However, unlike the inner diameter of the enlarged diameter portion 23, the inner diameter of the enlarged diameter portion 23b varies nonlinearly in the axial direction. More specifically, the cross-sectional shape of the enlarged diameter portion 23b along a plane including the axis of the connector 10b is a substantially circular arc that recedes away from the tube 90. This substantially circular arc connects the first tapered portion 21 and the cylindrical portion 25. The fixing layer end 81 of the fixing layer 80 is located at the enlarged diameter portion 23b. The catheter 1b is identical to the catheter 1 except for the above.

[0073] 9 is an enlarged cross-sectional view of a medical catheter 1c according to a third modification. Similar to the enlarged diameter portion 23 of the connector 10 (see FIG. 1C), the enlarged diameter portion 23c of the connector 10 is configured with a tapered surface (a conical surface, a so-called female tapered surface) whose inner diameter increases toward the second end 12. The taper angle of the tapered surface of the enlarged diameter portion 23c is greater than the taper angle of the tapered surface of the first tapered portion 21. The minimum inner diameter of the enlarged diameter portion 23c (the inner diameter at the end of the enlarged diameter portion 23c facing the first tapered portion 21) is equal to the maximum inner diameter of the first tapered portion 21 (the inner diameter at the end of the first tapered portion 21 facing the second end 12). The connector 10c does not include a cylindrical portion corresponding to the cylindrical portion 25 of the connector 10 (see FIGS. 1B and 1C) on the second end 12 side of the enlarged diameter portion 23. The enlarged diameter portion 23c extends to the second end 12. The fixation layer end 81 of the fixation layer 80 is located at the enlarged diameter portion 23c. The catheter 1c is the same as the catheter 1 except for the above.

[0074] In the above-described catheters 1a, 1b, and 1c, the fixation layer end 81 is located in the expanded diameter portion (23a, 23b, 23c) in the same manner as in the catheter 1 (see FIG. 1C). The fixation layer end 81 is located in the expanded diameter portion where the thickness of the fixation layer 80 gradually increases toward the second end 12. This is advantageous in reliably preventing separation of the tube 90 from the connector 10, starting from the portion 82 near the fixation layer end 81 (portion near the end) when a tube bending procedure is performed, as in the case of the catheter 1.

[0075] In the present invention, the shape of the inner peripheral surface of the through-hole 20 in the tube insertion portion 40 is not limited to that of the first embodiment.

[0076] For example, the first tapered portion 21 may be replaced with a cylindrical portion (second cylindrical portion). The second cylindrical portion is configured with a cylindrical surface whose inner diameter is constant in the axial direction (the longitudinal direction of the through hole 20). The inner diameter of the second cylindrical portion is equal to the maximum inner diameter of the second tapered portion 22 (the inner diameter at the end of the second tapered portion 22 on the second end 12 side) and the minimum inner diameter of the expanded diameter portion 23 (the inner diameter at the end of the expanded diameter portion 23 on the first end 11 side). The inner diameter of the second cylindrical portion is not limited, but can be set to be approximately the same as the outer diameter of the tube 90 (the outer diameter in an unloaded state).

[0077] The cylindrical portion 25 may be replaced with a tapered portion (third tapered portion). The third tapered portion is configured with a tapered surface (a conical surface, a so-called female tapered surface) whose inner diameter increases toward the second end 12. The taper angle of the tapered surface of the third tapered portion is not limited, but is preferably smaller than the taper angle of the tapered surface of the expanded diameter portion 23. The minimum inner diameter of the third tapered portion (the inner diameter of the third tapered portion at the end of the expanded diameter portion 23) is equal to the maximum inner diameter of the expanded diameter portion 23 (the inner diameter of the end of the expanded diameter portion 23 at the second end 12). As shown in FIG. 9 , the cylindrical portion 25 may be omitted.

[0078] Incidentally, providing cylindrical portion 25 adjacent to the opening on the second end 12 side of through hole 20 as in the first embodiment makes it easy to reduce opening diameter Dc (see FIG. 1C ) at second end 12 of through hole 20, and also makes it easy to reduce [(Dc - Dt) / 2] / L and Dc / Dt. This is advantageous in reducing the possibility of separation of tube 90 from connector 10 starting from end vicinity 82 or breakage of tube 90 at end vicinity 82.

[0079] In the first embodiment, the inner circumferential surface of the through hole 20 includes a second tapered portion 22 that is disposed on the first end 11 side of the first tapered portion 21 and is adjacent to the first tapered portion 21. The proximal end (more specifically, the outer circumferential surface end 91) of the tube 90 abuts against the second tapered portion 22. The effect of the second tapered portion 22 will be described.

[0080] In a conventional catheter 9, as shown in FIG. 4 , the proximal end surface 92 of the tube 90 axially faces a stepped surface 922 formed on the inner circumferential surface of the through hole 20. An adhesive layer 980 between the inner circumferential surface of the through hole 20 and the tube 90 exists not only in the cylindrical portion 921 but also in the stepped portion 922. In this configuration, air bubbles present in the adhesive layer 980 between the proximal end surface 92 and the stepped portion 922 may expand due to the atmosphere (e.g., temperature and air pressure) during sterilization treatment after the tube 90 is adhesively attached to the connector 910. The expansion of the air bubbles may separate the tube 90 from the inner circumferential surface of the through hole 20. This may reduce the adhesive strength of the tube 90 to the connector 910. Therefore, for example, if tension is applied to the tube 90 during use of the catheter 9, a problem may occur in which the tube 90 becomes detached from the connector 910.

[0081] In contrast, the connector 10 of the first embodiment does not have a stepped portion 922 that faces the proximal end surface 92 of the tube 90 in the axial direction. Therefore, the first embodiment does not have the problem of the conventional catheter 9, in which air bubbles expand in the adhesive layer 980 between the proximal end surface 92 and the stepped portion 922 during sterilization, reducing the adhesive strength of the tube 90 to the connector 910. The absence of a stepped portion 922 on the inner circumferential surface of the through hole 20 is advantageous in preventing a reduction in the adhesive strength of the tube 90 to the connector 10 during sterilization. However, in the present invention, as with the conventional catheter 9, the inner circumferential surface of the through hole 20 may be provided with a stepped portion 922 that faces the proximal end surface 92 of the tube 90 in the axial direction, and the proximal end surface 92 may be fixed to the stepped portion 922 via an adhesive layer (e.g., an adhesive layer) 80.

[0082] In the present invention, the dimensions (axial length, inner diameter, taper angle, etc.) of each part (second tapered part 22, first tapered part 21, enlarged diameter part 23, cylindrical part 25) that constitutes the inner surface of the through hole 20 in the tube insertion part 40 can be changed as appropriate.

[0083] (Embodiment 2) Figure 10 is a cross-sectional view of a medical catheter 2 according to Embodiment 2 of the present invention. The catheter 2 differs from the catheter 1 of Embodiment 1 in that a side hole 55 is provided in the base tube 50 of the connector 210. The side hole 55 communicates with the through hole 20 (i.e., the inner cavity of the base tube 50) and penetrates the base tube 50 so as to communicate the through hole 20 with the outside of the base tube 50. The side hole 55 extends non-parallel to the axis of the connector 210 (not shown) along a plane including the axis of the connector 210 (this plane coincides with the cross section of Figure 10). In the example of Figure 10, the side hole 55 is inclined with respect to the axis of the connector 210 so as to approach the second end 12 as it moves away radially outward from the axis of the connector 210.

[0084] The side holes 55 are useful in manufacturing the catheter 2. An example of a method for manufacturing the catheter 2 will now be described.

[0085] First, a connector 210 having a side hole 55 and a tube 90 are prepared. As shown in FIG. 11 , the connector 210 is held with a jig or the like (not shown) so that the second end 12 faces up and the axis of the connector 210 is parallel to the vertical direction. The tube 90 is inserted into the through hole 20 from the opening on the second end 12 side of the through hole 20. At this stage, no adhesive is applied to either the tube 90 or the connector 210. As shown in FIG. 11 , the tube 90 is inserted into the through hole 20 until the outer peripheral end 91 of the tube 90 abuts the inner peripheral surface of the second tapered portion 22 of the connector 210. The outer peripheral end 91 of the tube 90 is in liquid-tight contact with the second tapered portion 22, forming a continuous, liquid-tight seal in a circumferential ring shape between the outer peripheral end 91 and the second tapered portion 22. The tube 90 is held with a jig or the like (not shown) so that the tube 90 extends straight along the axis of the connector 210 within the through hole 20.

[0086] Uncured adhesive is prepared. The adhesive is stored in a container (not shown) connected to an elongated nozzle 287. The container may be, for example, a syringe. The nozzle 287 is inserted into the side hole 55, and a predetermined amount of uncured adhesive 285 is injected into the through-hole 20 through the nozzle 287. After leaving the nozzle 287, the adhesive 285 flows downward (toward the first end 11) through the gap between the outer circumferential surface 95 of the tube 90 and the inner circumferential surface of the through-hole 20. However, because a liquid-tight seal is formed between the outer circumferential end 91 of the tube 90 and the second tapered portion 22, the adhesive 285 cannot flow beyond the outer circumferential end 91 toward the first end 11 (male member 31).

[0087] The nozzle 287 is pulled out of the side hole 55. The adhesive 285 is then allowed to harden. The connector 210 and the tube 90 are then sterilized. In this manner, the catheter 2 shown in Figure 10 is obtained, in which the connector 210 is fixed to the tube 90 via the fixing layer 80.

[0088] In the manufacturing method of the catheter 1 described in the first embodiment, the adhesive 85 is applied to the outer circumferential surface 95 of the tube 90, and then the tube 90 is inserted into the through-hole 20 of the connector 10 (see FIG. 3 ). This method is suitable for use with an adhesive that can be easily applied thinly to the outer circumferential surface 95 of the tube 90, such as a solvent-based adhesive. However, when inserting the tube 90 into the through-hole 20, there is a possibility of an operational error in which the adhesive 85 is accidentally applied to the inner circumferential surface (e.g., the cylindrical portion 25) near the second end 12 of the through-hole 20. In contrast, in the manufacturing method of the catheter 2 described in the second embodiment, the tube 90 is inserted into the through-hole 20 of the connector 210, and then the adhesive 285 is injected into the gap between the outer circumferential surface 95 of the tube 90 and the inner circumferential surface of the through-hole 20 via the nozzle 287. This second embodiment can prevent the above-mentioned operational error from occurring in the first embodiment. The catheter 2 of the second embodiment is easy to manufacture and advantageous for improving yield.

[0089] In the second embodiment, the adhesive 285 preferably has fluidity. Specifically, a UV adhesive or an instant adhesive may be used as the adhesive 285. When a UV adhesive is used, the connector 210 preferably has translucency (or transparency) so that UV light can be irradiated onto the adhesive 285 between the outer circumferential surface 95 of the tube 90 and the inner circumferential surface of the through-hole 20.

[0090] In order to allow the adhesive 285 injected through the nozzle 287 to flow between the outer peripheral surface 95 of the tube 90 and the inner peripheral surface of the through-hole 20, it is preferable that a radial gap be formed between the outer peripheral surface 95 of the tube 90 and the inner peripheral surface of the through-hole 20. For this reason, it is preferable that the minimum inner diameter of the expanded diameter portion 23 (which is the same as the maximum inner diameter of the first tapered portion 21) and the minimum inner diameter of the first tapered portion 21 (which is the same as the maximum inner diameter of the second tapered portion 22) are slightly larger than the outer diameter of the tube 90 (outer diameter in an unloaded state).

[0091] The position of the side hole 55 in the axial direction of the connector 10 is not limited. For example, the opening 55a (see FIG. 10 ) of the side hole 55 on the through-hole 20 side may be provided near the second end 12, for example, in the cylindrical portion 25. However, if the opening 55a is located in the cylindrical portion 25, there is a possibility that an adhesive layer 80 adhering the tube 90 to the cylindrical portion 25 may be formed in the cylindrical portion 25. For this reason, the opening 55a is preferably provided in the expanded diameter portion 23. This allows for easy manufacture of a catheter 2 (see FIG. 10 ) in which the adhesive layer end 81 is located in the expanded diameter portion 23. Furthermore, in the expanded diameter portion 23, the gap between the outer circumferential surface 95 of the tube 90 and the inner circumferential surface of the through-hole 20 is relatively large. For this reason, compared to when the opening 55a is located in the first tapered portion 21, for example, having the opening 55a located in the expanded diameter portion 23 is advantageous for ensuring the fluidity of the adhesive 285 flowing from the nozzle 287.

[0092] As can be seen from the above manufacturing method, the fact that the side holes 55 are inclined so as to approach the second end 12 as they move radially outward from the axis of the connector 210 is advantageous in preventing uncured adhesive 285 from flowing out through the side holes 55 to the outside of the base tube 50 before the adhesive 285 is cured after the nozzle 287 is pulled out of the side holes 55.

[0093] The connector 210 may be provided with a plurality of side holes 55. A plurality of nozzles 287 can be inserted into the plurality of side holes 55, respectively, and the adhesive 285 can be injected through each nozzle 287. The plurality of side holes 55 can be arranged, without limitation, at equal angular intervals in the circumferential direction about the axis of the connector 210. Injecting the adhesive 285 from each of the plurality of nozzles 287 makes it easy to inject the adhesive 285 into the gap between the outer circumferential surface 95 of the tube 90 and the inner circumferential surface of the through hole 20 in a short period of time and approximately evenly in the circumferential direction.

[0094] Except for the above, the second embodiment is the same as the first embodiment. The description of the first embodiment also applies to the second embodiment.

[0095] The above-described first and second embodiments are merely examples, and the present invention is not limited to the above-described first and second embodiments, and can be modified as appropriate.

[0096] The connection portion 30 of the connector (10, 210) in the first and second embodiments is a male connector used for enteral nutrition, including a cylindrical male member 31 with a through hole 20, an outer tube 35 coaxially surrounding the male member 31, and a female thread 36 on the inner surface of the outer tube 35. A catheter (1, 2) equipped with this connector can be placed in a patient for use in enteral nutrition. Enteral nutrition frequently requires a tube bending procedure for catheters placed in a patient. As described above, the catheter of the present invention has excellent durability against the tube bending procedure. Therefore, the catheter of the present invention exhibits particularly significant effects when used as a catheter placed in a patient for enteral nutrition. However, the configuration of the connection portion 30 in the present invention is not limited to that of the first and second embodiments. For example, the connecting portion 30 may be a medical female connector including a hollow cylindrical tubular portion, a female tapered surface provided on the inner peripheral surface of the tubular portion whose inner diameter increases toward the tip of the tubular portion, and a helical protrusion provided on the outer peripheral surface of the tubular portion (see, for example, Patent Document 2). The configuration of the connecting portion 30 is not limited to the above and can be modified as appropriate depending on the application of the medical catheter.

[0097] Although the catheters 1 and 2 of the first and second embodiments are used by being placed in a patient for enteral nutrition, the catheter of the present invention is not limited to this. In the first and second embodiments, the effects of the catheter of the present invention were described in relation to the stress generated in the end portion 82 during the tube bending procedure performed during enteral nutrition. However, such stress can also be generated by the simple application of radially outward tension to the tube, in addition to the tube bending procedure. The effects of the present invention can be achieved similarly when radially outward tension is applied to the tube. Therefore, the catheter of the present invention may be any medical catheter in which such tension may be applied to the tube. Specifically, the catheter of the present invention may be a catheter used for infusion, anesthesia, dialysis (hemodialysis, peritoneal dialysis), etc., or a catheter used for tracheal intubation.

[0098] The present invention can be used as a medical catheter having a flexible hollow tube with a connector at one end, and is particularly suitable for use as a catheter for enteral nutrition, and as a catheter to be placed in a patient, particularly as a nasal catheter.

[0099] 1, 1a, 1b, 1c, 2 Medical catheter (catheter) 10, 10a, 10b, 10c, 210 Connector 11 First end 12 Second end 19 Connector shaft 20 Through hole 21 First tapered portion 22 Second tapered portion 23, 23a, 23b, 23c Expanded diameter portion 25 Cylindrical portion 30 Connection portion 31 Male member 35 Outer tube 36 Female thread 40 Tube insertion portion 41 Fixing portion 42 Separation portion 55 Side hole 80 Fixing layer 81 Fixing layer end 82 Portion near end 90 Tube 91 Outer peripheral surface end of tube 95 Outer peripheral surface of tube

Claims

1. A medical catheter comprising a flexible hollow tube and a connector provided at one end of the tube, wherein a through hole penetrates the connector along the axis of the connector to connect the first and second ends of the connector, the connector having a connection portion at the first end to be connected to a mating connector, and a tube insertion portion at the second end, with the tube inserted into the through hole, the tube insertion portion having a fastening portion where the tube is fastened to the connector via a fastening layer, and a separation portion located on the second end side of the fastening portion, wherein the inner peripheral surface of the through hole is separated radially from the outer peripheral surface of the tube, and the fastening layer end, which is the end of the fastening layer on the second end side, is separated from the second end toward the first end along the axis of the connector.

2. A medical catheter according to claim 1, wherein the length L along the axis of said connector from said second end to said fixing layer end is 5 mm or more and 10 mm or less.

3. A medical catheter according to claim 1, wherein the following relationship is satisfied: [(Dc - Dt) / 2] / L≦0.10, where Dc is the opening diameter of the through hole at the second end, Dt is the outer diameter of the tube, and L is the length along the axis of the connector from the second end to the end of the fixing layer.

4. A medical catheter according to claim 1, wherein the following relationship is satisfied: Dc / Dt≦1.30, where Dc is the opening diameter of the through hole at the second end and Dt is the outer diameter of the tube.

5. A medical catheter according to claim 1, wherein the inner peripheral surface of the through-hole in the tube insertion section includes an expanded diameter section, the expanded diameter section is a curved surface whose inner diameter increases toward the second end, and the end of the fixing layer is located in the expanded diameter section.

6. A medical catheter as described in claim 1, wherein the inner circumferential surface of the through hole in the tube insertion portion includes a first tapered portion, an expanded diameter portion, and a cylindrical portion arranged adjacent to one another from the first end toward the second end, the first tapered portion is a conical surface whose inner diameter increases toward the second end, the expanded diameter portion is a curved surface whose inner diameter increases toward the second end, the cylindrical portion is a cylindrical surface whose inner diameter is constant in the axial direction of the connector and whose inner diameter is larger than the outer diameter of the tube, the adhesive layer extends from the first tapered portion toward the expanded diameter portion, and an end of the adhesive layer is located at the expanded diameter portion.

7. A medical catheter as described in claim 1, wherein the inner peripheral surface of the through hole includes a first tapered portion and a second tapered portion arranged adjacent to each other from the second end toward the first end, the first tapered portion and the second tapered portion are both conical surfaces whose inner diameters increase toward the second end, the fixing layer fixes the outer peripheral surface of the tube to the first tapered portion, and the outer peripheral surface end, which is the proximal end of the outer peripheral surface of the tube, abuts against the second tapered portion.

8. A medical catheter as described in claim 1, wherein the connecting portion is a male connector used for enteral nutrition, comprising a cylindrical male member having the through hole, an outer tube surrounding the male member coaxially with the male member, and a female thread provided on the inner surface of the outer tube.

9. A medical catheter according to claim 1, wherein a side hole communicating with said through hole and not parallel to the axis of said connector is provided in said tube insertion portion.

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