Medical catheter

Abstract

To increase freedom of selection relating to a diameter of a tube, while securing interoperability with the conventional connector.SOLUTION: A connector 10 is provided at a base end of a flexible hollow light guide tube 50. The connector 10 includes a hollow cylindrical member 21. The tube 50 is inserted into the connector 10 so as to expose the base end face 51 of the tube 50 to the tip of the cylindrical member 21. The tube 50 includes, outside the connector 10, a base diameter part 52 having a specified inside diameter. The inside diameter of the tube 50 at the base end face 51 is different from the inside diameter of the base diameter part 52.SELECTED DRAWING: Figure 2B

Description

[Technical Field]

[0001] The present invention relates to a medical catheter having a connector provided at the proximal end of a light-guiding tube. [Background technology]

[0002] In the medical field, flexible hollow tubes are sometimes inserted into patients for examinations or treatments. For example, enteral nutrition is performed to supply liquid nutrients from an external source to patients who have difficulty chewing or swallowing, by delivering the nutrients directly to the stomach through a tube inserted through the mouth or nose. In enteral nutrition, it is necessary to confirm that the tip of the tube is positioned within the stomach before delivering the nutrients.

[0003] Patent Document 1 describes a system for detecting the tip position of a medical tube, which uses the tube itself as a light guide. Specifically, while the tube is inserted into a patient, light is incident on the proximal end surface of the tube and emitted from the tip of the tube. The position of the tube tip can be confirmed by observing this light from outside the body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2021 / 024992A1 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-119837 Summary of the Invention [Problem to be solved by the invention]

[0005] In tube feeding, a connector must be provided at the proximal end of the tube to form a flow path for the nutritional supplement from the container storing the nutritional supplement to the stomach. It is desirable that the connector be compatible with connectors used in conventional tube feeding.

[0006] In Patent Document 1, the base end surface of the tube where light enters is arranged on approximately the same plane as the tip of the tubular member (male member) of the connector (FIGS. 2A and 2B of Patent Document 1). In this configuration, the opening diameter of the flow path at the tip of the tubular member (hereinafter referred to as the "tip opening diameter") matches the inner diameter of the tube. In order to ensure compatibility with conventional connectors in terms of tip opening diameter, it is necessary to use a tube with the same inner diameter as the tip opening diameter of the conventional connector. Therefore, there is an issue of limited freedom of choice in terms of tube diameter.

[0007] The present invention aims to provide a medical catheter having a connector at the base end of a light-guiding tube, while ensuring compatibility with conventional connectors and increasing the freedom of choice regarding the diameter of the tube. [Means for solving the problem]

[0008] The medical catheter of the present invention comprises a flexible, hollow light-guiding tube and a connector provided at the base end of the light-guiding tube. The connector comprises a hollow, cylindrical tubular member. The light-guiding tube is inserted into the connector so that the base end surface of the light-guiding tube is exposed at the tip of the tubular member. The light-guiding tube comprises a base portion having a constant inner diameter outside the connector. The inner diameter of the light-guiding tube at the base end surface is different from the inner diameter of the base portion. [Effects of the Invention]

[0009] In the present invention, the inner diameter of the base end surface of the light-guiding tube can be set to the same as the diameter of the tip opening of a conventional connector, while the inner diameter of the base portion can be selected arbitrarily. Therefore, according to the present invention, the degree of freedom in selecting the tube diameter can be increased while ensuring compatibility with conventional connectors. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 shows a method for detecting the tip position of a tube using a medical catheter according to a first embodiment of the present invention. [Figure 2A]FIG. 2A is a perspective view of the proximal end portion of the medical catheter according to the first embodiment of the present invention. [Figure 2B] FIG. 2B is a cross-sectional view of the proximal end portion of the medical catheter according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view of the proximal end portion of the medical catheter according to the first embodiment of the present invention connected to the light source device. [Figure 4] FIG. 4 is a cross-sectional view of the proximal end portion of a medical catheter according to a second embodiment of the present invention. [Figure 5] FIG. 5 is a cross-sectional view of the proximal end portion of a medical catheter according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] In one aspect of the present invention, the light-guiding tube may further include a variable diameter portion extending from the base end surface and having a constant inner diameter, and a variable diameter portion whose inner diameter varies between the base diameter portion and the variable diameter portion. Such a tube can be manufactured relatively easily.

[0012] In one aspect of the present invention, the inner diameter of the light-guiding tube may vary within the connector. This allows the strength of the tube to be substantially constant in its longitudinal direction outside the connector. This is advantageous in preventing kinking, which is a blockage of the flow path due to bending of the tube.

[0013] In one aspect of the present invention, the inner diameter of the light-guiding tube may vary outside the connector. According to this aspect, both the inner diameter and the outer diameter of the tube can be made constant within the connector. This is advantageous for simplifying the shape of the connector.

[0014] In one aspect of the present invention, the outer diameter of the light-guiding tube may be constant within the cylindrical member, which is advantageous for improving the molding precision of the cylindrical member (particularly its outer peripheral surface).

[0015] In one aspect of the present invention, the base end surface of the light-guiding tube may form a common plane with the tip end of the tubular member, which is advantageous in ensuring compatibility with conventional connectors.

[0016] In one aspect of the present invention, the connector may further include a hollow cylindrical base pipe arranged coaxially with the tubular member. The light-guiding tube may be led out from the base pipe. According to this aspect, first, the base pipe can be used to adhesively fix the tube to the connector, and second, the operator can grasp the connector by the base pipe, thereby preventing contamination of the tubular member by the operator's fingers, etc.

[0017] In one aspect of the present invention, the connector may further include an outer tube surrounding the tubular member and a female thread provided on an inner circumferential surface of the outer tube facing the tubular member. According to this aspect, the connector of the present invention can be configured to be compatible with a male connector provided at the proximal end of a conventional nasogastric tube used in tube feeding.

[0018] 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.

[0019] In the present invention, the "axis" of a member (e.g., a connector or a cylindrical member) refers to the central axis of the member. The "axis" passes through the center of a circle included in the member and / or coincides with the central axis of a cylinder or cone (taper) included in the member. The direction along a straight line perpendicular to the axis is called the "radial direction." In the radial direction, the side closer to the axis is called the "inner" side, and the side farther from the axis is called the "outer" side. The direction of rotation around the axis is called the "circumferential direction."

[0020] (Embodiment 1) An embodiment of the present invention applied to nasogastric tube feeding will be described. As shown in FIG. 1, a medical catheter (hereinafter simply referred to as a "catheter") 1 according to a first embodiment of the present invention includes a flexible, hollow, light-conducting tube (hereinafter simply referred to as a "tube") 50 and a connector 10 attached to the proximal end of the tube 50. The tube 50 is inserted through the nasal cavity of a patient 90, and a distal end 55 of the tube 50 reaches a stomach 91. The tube 50 is flexible enough to bend and deform freely. The tube 50 is a hollow, tubular object having a continuous flow path 59 (see FIG. 2B described below) formed along its entire length. The flow path 59 communicates with the outside world at both longitudinal ends of the tube 50 (i.e., the proximal end and the distal end 55). When performing tube feeding, a liquid nutrient is administered to the patient's stomach 91 through the flow path 59 of the tube 50. The connector 10 can be repeatedly connected to and disconnected from a light source device 70. When the connector 10 is connected to the light source device 70, light from a light source 78 (see FIG. 3 described later) built into the light source device 70 passes through the tube 50 and is emitted from the tip 55 of the tube 50. The light from the tip 55 penetrates the body of the patient 90 and illuminates the body surface. The surgeon can confirm the position of the tip 55 of the tube 50 from the position of the light emission on the body surface of the patient 90.

[0021] FIG. 2A is a perspective view of the connector 10 provided at the base end of the tube 50. FIG. 2B is a cross-sectional view of the connector 10 taken along a plane including the axis (not shown) of the connector 10. The connector 10 has a connector portion 20 at its tip (the upper end of the connector 10 in FIGS. 2A and 2B) and a connecting pipe 30 at its base end. The connector portion 20 has a tubular member (a male member in the first embodiment) 21 having a hollow tubular shape, and an outer tube 27 surrounding the tubular member 21. The connecting pipe 30 has a hollow tubular shape. The connector portion 20 (or the tubular member 21) and the connecting pipe 30 are arranged coaxially. A through-hole 11 penetrates the connector 10 along the axis of the connector 10 from the tubular member 21 to the connecting pipe 30. The inner diameter of through hole 11 varies within connector 10 so that the inner diameter at the tip of tubular member 21 (the upper end of tubular member 21 in FIGS. 2A and 2B) is smaller than the inner diameter at the tip of connecting pipe 30 (the lower end of connecting pipe 30 in FIGS. 2A and 2B). Specifically, connecting pipe 30 is provided with inner diameter varying section 14, at which the inner diameter of through hole 11 varies in a substantially tapered shape (or a substantially conical surface shape). Through hole 11 includes small inner diameter section 13, which has a relatively small and constant inner diameter, on the tip side of connector 10 (the tubular member 21 side) with respect to inner diameter varying section 14, and includes standard inner diameter section 12, which has a relatively large and constant inner diameter, on the base end side of connector 10 (the connecting pipe 30 side) with respect to inner diameter varying section 14.

[0022] The outer peripheral surface of the tubular member 21 is provided with a male tapered surface 23 whose outer diameter decreases toward the tip of the tubular member 21. The outer peripheral surface of the tubular member 21 further has a tip tapered surface 24, which is located further toward the tip of the male tapered surface 23 and has a larger taper angle than the male tapered surface 23. The tip of the tubular member 21 (part or all of the tip tapered surface 24) protrudes in the axial direction of the connector 10 beyond the tip of the outer tube 27. The fact that the tubular member 21 protrudes beyond the outer tube 27 is advantageous in facilitating connection of the connector 10 (or connector portion 20) to a female connector (not shown; see, for example, Figures 5A and 5B of Patent Document 2).

[0023] A flange 26 protrudes radially outward from the base end of the tubular member 21. An outer tube 27 extends from the circular outer peripheral edge of the flange 26 toward the same side as the tubular member 21 (the tip end side of the connector 10). The outer tube 27 has a substantially cylindrical shape and is arranged coaxially with the tubular member 21. The outer tube 27 is spaced apart from the tubular member 21 in the radial direction. A female thread 28 is provided on the inner peripheral surface of the outer tube 27 facing the tubular member 21.

[0024] The connector portion 20 is preferably configured to be compatible with a male connector used in tube feeding (see, for example, FIGS. 4A and 4B of Patent Document 2).

[0025] The material of the connector 10 is not limited, but is preferably a material having sufficient mechanical strength (rigidity) to prevent substantial deformation due to external forces. Examples of such materials that can be used include resin materials such as polypropylene, acrylonitrile-butadiene-styrene copolymer, polycarbonate, polyacetal, polystyrene, polyamide, polyethylene, and rigid polyvinyl chloride. The connector 10 can be integrally molded as a single component using the above resin materials by injection molding or the like.

[0026] A flexible, hollow tube 50 is inserted into the through-hole 11 of the connector 10. The lumen of the tube 50, which is continuous throughout its entire length (see FIG. 1 ), constitutes a flow path 59 of the tube 50 (and further the catheter 1). The diameter of the tube 50 (in the present invention, the "diameter" of the tube 50 includes both the inner diameter and the outer diameter of the tube 50 unless otherwise specified) is not constant throughout its entire length. Specifically, the tube 50 includes, in order from the distal end 55 (see FIG. 1 ) side to the proximal end side, a base diameter section 52, a diameter-changing section 54, and a small diameter section (different diameter section) 53. The diameters (inner diameter and outer diameter) of the base diameter section 52 and the small diameter section 53 are constant in the longitudinal direction of the tube 50, but the small diameter section 53 has a smaller diameter than the base diameter section 52. In the diameter changing portion 54, due to the difference in diameter between the base diameter portion 52 and the small diameter portion 53, the diameter (inner diameter and outer diameter) changes in a substantially tapered shape (or a substantially conical surface shape).

[0027] The material of the tube 50 is not limited, but is preferably flexible and light-guiding, and examples of resins that can be used include polyurethane, acrylic, silicone, polyethylene, styrene-based elastomer, polybutadiene, polyolefin, and the like.

[0028] The tube 50 is preferably constructed as a single, continuous piece made of the same material throughout its entire length, from the base-side end surface (base-side surface) 51 to the tip 55 (see FIG. 1 ). The majority of the length of the tube 50 toward the tip 55 is a base diameter section 52 having a constant diameter (inner and outer diameters). A diameter-changing section 54 and a small diameter section 53, each having a diameter different from that of the base diameter section 52, are provided near the base end of the tube 50. There are no limitations on the method for forming the variable diameter section in the tube 50. One example is a thermoforming method in which a tube having a constant diameter (e.g., the same diameter as the base diameter section 52) is cut to a predetermined length, and the portion near the base end is molded into a predetermined shape using a heated mold, followed by immediate quenching. Another example is a method similar to blow molding, in which heated and molten tube material is continuously extruded through a nozzle into a tubular shape while air is blown into the material to expand it so that it adheres closely to the inner surface of a mold of a predetermined shape.

[0029] The tube 50, which includes the base diameter portion 52, the diameter changing portion 54, and the small diameter portion 53, and the connector 10 are manufactured separately. Then, the tube 50 is inserted into the through-hole 11 of the connector 10 from the base end side (the base pipe 30 side) of the connector 10, with the base end side (the small diameter portion 53 side) of the tube 50 leading. The small diameter portion 53, the diameter changing portion 54, and the base diameter portion 52 of the tube 50 are fitted into the small inner diameter portion 13, the inner diameter changing portion 14, and the standard inner diameter portion 12 of the connector 10, respectively. Preferably, the outer peripheral surface of the tube 50 is in close contact with the inner peripheral surface of the through-hole 11 of the connector 10 with substantially no gaps over the entire length of the through-hole 11. The tube 50 is fixed to the connector 10 (particularly the base pipe 30) with an adhesive (e.g., a solvent adhesive) or the like so as not to separate from the connector 10. The tube 50 is led out of the base pipe 30 toward the side opposite the tubular member 21. The base end surface 51 of the tube 50 is an annular flat surface perpendicular to the axis of the connector 10. The base end surface 51 forms a plane common to the tip of the tubular member 21 (the tip of the tip tapered surface 24) and is exposed to the outside.

[0030] In this embodiment, light incident on the base end surface 51 of the tube 50 passes through the tube 50 (the portion between the inner and outer circumferential surfaces of the tube 50 that constitutes the thickness of the tube 50) and exits from the tip 55 (see FIG. 1), causing the tip 55 to emit light. In order to improve the brightness (luminous flux) of the tip 55, it is preferable to reduce the light loss between the base end surface 51 and the tip 55. To achieve this, it is effective to reduce the light (leakage light) that is emitted from the outer circumferential surface of the tube 50 to the outside world between the base end surface 51 and the tip 55. Means for reducing leaked light include, but are not limited to, one or a combination of two or more of the following: (1) smoothing the outer surface of the tube 50; (2) covering the outer surface of the tube 50 with a coating material having a lower refractive index than the tube 50; (3) providing a reflective layer (e.g., a metal vapor deposition layer of silver, aluminum, etc.) on the outer surface of the tube 50; (4) constructing the tube 50 with a multilayer structure having at least an inner layer with a high refractive index and an outer layer with a low refractive index.

[0031] Regardless of the orientation of tip 55 within stomach 91 (see FIG. 1), in order to illuminate the body surface of patient 90 with light from tip 55, it is preferable that light be emitted radially from tip 55 of tube 50 in a direction perpendicular or oblique to the longitudinal direction of tube 50. To achieve this, it is preferable to provide tip 55 of tube 50 with an inclined light emission surface and / or to provide a reflective or refractive member facing the light emission surface of tip 55 of tube 50, etc.

[0032] FIG. 3 is a cross-sectional view of the catheter 1 connected to a light source device 70. The light source device 70 includes a holding portion 71 that houses and holds the connector 10 (particularly the connector portion 20), and a light source 78 that is positioned deeper than the holding portion 71. The holding portion 71 includes a holding tube 72 and a stepped surface 73. The inner circumferential surface of the holding tube 72 is a cylindrical surface with approximately the same diameter as the outer tube 27. The stepped surface 73 is provided at a position a predetermined distance from the open end of the holding tube 72 so as to protrude radially inward from the inner circumferential surface of the holding tube 72. The light source 78 is arranged coaxially with the holding portion 71 (or the holding tube 72). The connector 10 (or the connector portion 20) is inserted into the holding portion 71 until the tip of the outer tube 27 abuts against the stepped surface 73. The holding tube 72 positions the connector 10 (or the tubular member 21) coaxially with the light source 78. The stepped surface 73 positions the connector 10 (or the cylindrical member 21) at a predetermined distance in the axial direction from the light source 78. The tip of the cylindrical member 21 (or the base end surface 51 of the tube 50) faces the light source 78.

[0033] The light source 78 emits light toward the tip of the cylindrical member 21. The light emitted from the light source 78 is incident on the base end surface 51 of the tube 50.

[0034] The light source 78 may be, but is not limited to, a light-emitting diode (LED). The light emitted by the light source 78 is preferably visible light or near-infrared light. The wavelength of the light is, but is not limited to, preferably 360 nm or more, more preferably 630 nm or more, and 3000 nm or less, even more preferably 780 nm or less. Light with a wavelength in this range has high transmittance to the human body, is minimally invasive to the human body, and is highly safe. Visible light can be observed with the naked eye, making it easy to confirm the position of the tip 55 of the tube 50. Near-infrared light has better transparency than visible light and can be observed using a dedicated camera such as an infrared camera. In one example, light with a wavelength of 630 nm can be used as visible light, or light with a wavelength of 780 nm can be used as near-infrared light. To ensure that the light emitted from the light source 78 efficiently enters the base end surface 51 of the tube 50, the light source 78 may be provided with a lens, and / or a lens may be provided between the light source 78 and the tubular member 21 (or the base end surface 51).

[0035] A method of using the catheter 1 of the first embodiment will be described.

[0036] A catheter 1 is prepared, with a connector 10 attached to the proximal end of a tube 50. The tube 50 is inserted into the nasal cavity of a patient 90 in the same manner as a general nasal catheter (see FIG. 1). The connector 10 is connected to a light source device 70, and a light source 78 (see FIG. 3) is turned on. Light emitted from the light source 78 enters the proximal end surface 51 of the tube 50, passes through the tube 50, and is emitted from the tip 55. The light from the tip 55 passes through the patient 90. The surgeon can confirm the position of the tip 55 from the position of the light emission on the body surface of the patient 90. The light can be confirmed with the naked eye or through an infrared camera depending on its wavelength.

[0037] Similar to the insertion of a general nasal catheter, tube 50 with a stylet (sometimes called a guidewire) already inserted into flow path 59 may be inserted into patient 90. The proximal end of the stylet can be led out from connector 10. In this case, after the stylet is pulled out of tube 50, connector 10 is connected to light source device 70.

[0038] The tube 50 may be inserted into the patient 90 with the optical fiber inserted into the flow path 59 so that the tip of the optical fiber reaches the tip 55 of the tube 50. Using the light source device 70, light is emitted not only from the tip 55 but also from the tip of the optical fiber. Since the light flux from the tip 55 is increased, the position of the tip 55 can be confirmed more accurately. After confirming that the tip of the tube 50 has reached the stomach, the optical fiber is pulled out of the tube 50.

[0039] After confirming that the tip 55 of the tube 50 has reached the stomach, the light source device 70 is separated from the connector 10. Then, the connector 10 is connected to a connector (female connector; see, for example, Figures 5A and 5B of Patent Document 2) provided at the downstream end of a tube (commonly called an enteral feeding set) that delivers the nutritional supplement. The nutritional supplement passes through the flow path 59 of the tube 50, flows out from the tip 55, and is administered to the patient.

[0040] The connector 10 is left in the patient 90 together with the tube 50 for several days. During this time, the tube 50 may curl up, causing the tip 55 to move. For this reason, at predetermined intervals (for example, immediately before administering nutrients to the patient 90), the connector 10 is connected to a light source device 70, and the tip 55 is illuminated to confirm its position.

[0041] As described above, in the first embodiment, the base end surface 51 of the light-guiding tube 50 is exposed at the tip of the tubular member 21 of the connector 10. Therefore, when light from the light source 78 is emitted toward the tip of the tubular member 21, the light enters the base end surface 51 of the tube 50, passes through the tube 50, and exits from the tip 55. The tube 50 itself can be used as a light guide path to cause the tip 55 of the tube 50 to emit light. The light from the tip 55 can be observed through the body of the patient 90. Therefore, the position of the tip 55 of the tube 50 can be easily and accurately detected.

[0042] The connector portion 20 of the connector 10 can be configured to be compatible with a male connector (hereinafter referred to as an "existing male connector"; see, for example, Figures 4A and 4B of Patent Document 2) that is provided at the base end of a tube that constitutes a conventional enteral feeding catheter. In this case, the connector 10 (particularly the connector portion 20) can be connected to a female connector that can be connected to an existing male connector (see, for example, Figures 5A and 5B of Patent Document 2) in the same way as connecting an existing male connector to the female connector.

[0043] Existing male connectors may have standards for shape, etc. To ensure compatibility with existing male connectors, the opening diameter of the flow path at the tip of the tubular member 21 (hereinafter referred to as the "tip opening diameter") must also be the same as that of the existing male connector. In the first embodiment, the tip opening diameter depends not on the through-hole 11 of the tubular member 21 but on the flow path 59 of the tube 50 inserted into the through-hole 11. More specifically, the tip opening diameter depends on the inner diameter of the flow path 59 in the small diameter portion 53 of the tube 50. Compatibility with existing male connectors can be ensured with respect to the tip opening diameter by making the inner diameter of the small diameter portion 53, which determines the tip opening diameter of the flow path 59, the same as the tip opening diameter of the flow path of the existing male connector. The base diameter portion 52, which accounts for the majority of the overall length of the tube 50, may have an inner diameter different from the tip opening diameter, i.e., the small diameter portion 53. Therefore, the catheter 1 of the first embodiment can improve the freedom of selection of the diameter of the tube 50 while ensuring compatibility with existing male connectors. For example, by using a tube 50 having a desired constant diameter throughout its entire length and having a small diameter portion 53 and a diameter-changing portion 54 formed near the base end so that the small diameter portion 53 has the same inner diameter as the tip opening diameter of an existing male connector, compatibility with existing male connectors can be ensured.

[0044] In the first embodiment, the base diameter portion 52 of the tube 50 has an inner diameter larger than the diameter of the tip opening of the flow path 59. This is advantageous in increasing the cross-sectional area of the flow path 59 over most of the entire length of the tube 50 and improving the fluidity of the nutrient solution flowing through the flow path 59.

[0045] (Embodiment 2) 4 is a cross-sectional view of the proximal end portion of a catheter 2 according to a second embodiment of the present invention. Similar to the catheter 1 of the first embodiment, the catheter 2 includes a flexible, hollow, light-guiding tube 50 and a connector 10 provided at the proximal end of the tube 50. The second embodiment differs from the first embodiment in the inner diameter of the through-hole 11 of the connector 10 and the diameter of the proximal end portion of the tube 50.

[0046] The inner diameter of through hole 11 of connector 10 varies within connector 10 so that the inner diameter at the tip end side of tubular member 21 is larger than the inner diameter at the tip end side of base pipe 30. Specifically, a varying inner diameter section 214 is provided within base pipe 30, where the inner diameter of through hole 11 varies in a generally tapered shape (or a generally conical surface shape). Through hole 11 includes a large inner diameter section 213 having a relatively large and constant inner diameter on the tip end side of connector 10 (tubular member 21 side) with respect to varying inner diameter section 214, and a standard inner diameter section 212 having a relatively small and constant inner diameter on the base end side of connector 10 (base pipe 30 side) with respect to varying inner diameter section 214.

[0047] Tube 50 is provided with, in order from tip 55 (see FIG. 1) side to base end side, base diameter section 252, diameter changing section 254, and large diameter section (different diameter section) 253. The diameters (inner diameter and outer diameter) of base diameter section 252 and large diameter section 253 are constant in the longitudinal direction of tube 50, but large diameter section 253 has a larger diameter than base diameter section 252. In diameter changing section 254, the diameters (inner diameter and outer diameter) change in a generally tapered shape (or a generally conical surface shape) due to the difference in diameter between base diameter section 252 and large diameter section 253.

[0048] As in the first embodiment, in the second embodiment, the tube 50 and the connector 10 are manufactured separately. Then, in the second embodiment, the tube 50 is inserted into the through-hole 11 of the connector 10 from the distal end (the tubular member 21 side) of the connector 10, with the distal end (the proximal diameter portion 252 side) of the tube 50 at the leading edge. The large inner diameter portion 253, the diameter changing portion 254, and the proximal diameter portion 252 of the tube 50 are fitted into the large inner diameter portion 213, the inner diameter changing portion 214, and the nominal inner diameter portion 212 of the connector 10, respectively. Preferably, the outer peripheral surface of the tube 50 is in close contact with the inner peripheral surface of the through-hole 11 of the connector 10 with substantially no gaps over the entire length of the through-hole 11. The tube 50 is fixed to the connector 10 (particularly the connecting pipe 30) with an adhesive (e.g., a solvent adhesive) or the like so as not to be separated from the connector 10. The tube 50 is led out of the connecting pipe 30 toward the side opposite the tubular member 21. The base end surface 51 of the tube 50 forms the same plane as the tip of the cylindrical member 21 (the tip of the tip tapered surface 24), and is exposed to the outside.

[0049] The catheter 2 can be used in the same manner as the catheter 1 of the first embodiment.

[0050] As in the first embodiment, in the second embodiment, compatibility with existing male connectors can be ensured with respect to the diameter of the tip opening by making the inner diameter of the large diameter portion 253, which defines the diameter of the tip opening of the flow path 59, the same as the diameter of the tip opening of the flow path of the existing male connector. The base diameter portion 252, which accounts for the majority of the overall length of the tube 50, may have an inner diameter different from the diameter of the tip opening, i.e., the large diameter portion 253. Therefore, the catheter 2 can improve the degree of freedom in selecting the diameter of the tube 50 while ensuring compatibility with existing male connectors. For example, compatibility with existing male connectors can be ensured by using a tube 50 in which the large diameter portion 253 and the diameter changing portion 254 are formed in the portion near the base end of a tube having a desired constant diameter throughout its entire length so that the large diameter portion 253 has the same inner diameter as the diameter of the tip opening of the existing male connector.

[0051] In the second embodiment, the base diameter portion 252 of the tube 50 has an inner diameter smaller than the diameter of the tip opening of the flow path 59. The base diameter portion 252 with a small inner diameter also has a small outer diameter. The tube 50 having such a small base diameter portion 252 is useful, for example, as a nasal catheter for children.

[0052] The base end surface 51, onto which light from the light source 78 is incident, is formed by a relatively large diameter portion 253. Therefore, the base end surface 51 has a larger cross-sectional area than the cross-sectional area of the tube 50 at the base diameter portion 252. This allows more light to be incident on the base end surface 51, which is advantageous for improving the brightness (luminous flux) of the tip 55 of the small diameter base diameter portion 252.

[0053] 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.

[0054] (Embodiment 3) 5 is a cross-sectional view of the proximal end portion of a catheter 3 according to a third embodiment of the present invention. Similar to the catheters 1 and 2 of the first and second embodiments, the catheter 3 includes a flexible, hollow, light-guiding tube 50 and a connector 10 provided at the proximal end of the tube 50. The third embodiment differs from the first and second embodiments in the inner diameter of the through-hole 11 of the connector 10 and the diameter of the proximal end portion of the tube 50.

[0055] The inner diameter of the through hole 11 of the connector 10 is constant over the entire length of the through hole 11 .

[0056] As in the first embodiment, the tube 50 includes, in order from the distal end 55 (see FIG. 1) side to the proximal end side, a base diameter section 352, a diameter changing section 354, and a small diameter section (different diameter section) 353. The diameters (inner diameter and outer diameter) of the base diameter section 352 and the small diameter section 353 are constant in the longitudinal direction of the tube 50, but the small diameter section 353 has a smaller diameter than the base diameter section 352. In the diameter changing section 354, the diameters (inner diameter and outer diameter) change in a generally tapered shape (or a generally conical surface shape) due to the difference in diameter between the base diameter section 352 and the small diameter section 353.

[0057] As in the first embodiment, in the third embodiment, the tube 50 and the connector 10 are manufactured separately. Then, the small diameter portion 353 of the tube 50 is inserted into the through hole 11 of the connector 10 from the base end side (the main pipe 30 side) of the connector 10. The small diameter portion 353 of the tube 50 is fitted into the through hole 11 of the connector 10. Preferably, the outer peripheral surface of the small diameter portion 353 is in close contact with the inner peripheral surface of the through hole 11 of the connector 10 with substantially no gap over the entire length of the through hole 11. The tube 50 is fixed to the connector 10 (particularly the main pipe 30) with an adhesive (e.g., a solvent adhesive) or the like so that it does not separate from the connector 10. The tube 50 is led out of the main pipe 30 toward the opposite side to the tubular member 21. The diameter changing portion 354 is arranged outside the connector 10 and in the vicinity of the connector 10 (particularly the main pipe 30). The base end surface 51 of the tube 50 forms the same plane as the tip of the cylindrical member 21 (the tip of the tip tapered surface 24), and is exposed to the outside.

[0058] The catheter 3 can be used in the same manner as the catheter 1 of the first embodiment.

[0059] As in the first embodiment, in the third embodiment, compatibility with existing male connectors can be ensured with respect to the diameter of the tip opening by making the inner diameter of the small diameter portion 353, which defines the diameter of the tip opening of the flow path 59, the same as the diameter of the tip opening of the flow path of the existing male connector. The proximal diameter portion 352, which accounts for the majority of the overall length of the tube 50, may have an inner diameter different from the diameter of the tip opening, i.e., the small diameter portion 353. Therefore, the catheter 3 can improve the degree of freedom in selecting the diameter of the tube 50 while ensuring compatibility with existing male connectors. For example, compatibility with existing male connectors can be ensured by using a tube 50 in which the small diameter portion 353 and the diameter changing portion 354 are formed in the portion near the base end of a tube having a desired constant diameter throughout its entire length so that the small diameter portion 353 has the same inner diameter as the diameter of the tip opening of the existing male connector.

[0060] In the third embodiment, the base diameter portion 352 of the tube 50 has an inner diameter larger than the diameter of the tip opening of the flow path 59. This is advantageous in increasing the cross-sectional area of the flow path 59 over most of the entire length of the tube 50 and improving the fluidity of the nutrient solution flowing through the flow path 59.

[0061] Unlike the first and second embodiments, the diameters (inner and outer diameters) of the tube 50 vary outside the connector 10. The inner diameter of the through hole 11 of the connector 10 is constant over the entire length of the through hole 11. This simplifies the shape of the connector 10. This is advantageous in simplifying the mold shape and facilitating the manufacture of the connector 10 when manufacturing the connector 10 by injection molding.

[0062] In the third embodiment, the diameter changing section 354, which changes the diameter of the tube 50, is located near the connector 10. This configuration increases the ratio of the proximal diameter section 352 to the overall length of the tube 50. In catheters, the length of the portion of the tube having a predetermined and constant outer diameter (the proximal diameter section 352 in the third embodiment) is generally standardized. Therefore, by locating the diameter changing section 354 near the connector 10, it is possible to prevent the overall length of the tube from being unnecessarily long. If the tube is too long, problems may arise, such as a decrease in the fluidity of the nutrient flowing through the flow path 59, complication in handling the tube, or an increase in the cost of the catheter. In the third embodiment, these problems are less likely to occur. Generally, the distance between the connector 10 and the diameter changing section 354 is not limited, but is preferably 200 mm or less, more preferably 100 mm or less, and particularly preferably 50 mm or less. However, in the present invention, the position of the diameter changing section 354 is arbitrary. For example, the diameter changing section 354 may be located near the distal end 55 of the tube 50 (see FIG. 1 ). In this case, the portion from connector 10 to diameter changing portion 354 is formed by small diameter portion 353 with a constant diameter.

[0063] In the third embodiment, the base portion 352 has a diameter (inner diameter and outer diameter) larger than the diameter of the tip opening, but the present invention is not limited to this, and the base portion 352 may have a diameter (inner diameter and outer diameter) smaller than the diameter of the tip opening, similar to the tube 50 constituting the catheter 2 of the second embodiment. Such a catheter is useful as a nasal catheter for children with improved brightness at the tip 55, similar to the catheter 2 of the second embodiment.

[0064] Except for the above, the present embodiment 3 is the same as the embodiment 1. The description of the embodiment 1 also applies to the present embodiment 3.

[0065] The above-described first to third embodiments are merely examples, and the present invention is not limited to the above-described first to third embodiments, and can be modified as appropriate.

[0066] In the present invention, the tube 50 has a base portion outside the connector 10, the base portion having a constant inner diameter in the longitudinal direction of the tube 50. The inner diameter (tip opening diameter) at the base end surface 51 of the tube 50 is different from the inner diameter of the base portion. There are no restrictions on the arrangement of the base portion relative to the connector 10. For example, as in embodiments 1 and 2, a portion of the base portion may be housed within the connector 10. Alternatively, as in embodiment 3, the base portion may be arranged away from the connector 10.

[0067] In the present invention, the base portion accounts for most of the overall length of the tube 50. Specifically, the length of the base portion is preferably 80% or more of the overall length of the tube 50, more preferably 85% or more, and even more preferably 90% or more.

[0068] In the present invention, the inner diameter of the tube may vary in any manner between the base end surface 51 and the base diameter portion. However, preferably, the tube includes a different diameter portion extending from the base end surface 51 and a variable diameter portion whose inner diameter varies between the base diameter portion and the different diameter portion. The different diameter portion has a constant inner diameter in the longitudinal direction of the tube 50 and defines the inner diameter at the base end surface 51 of the tube. For example, like the small diameter portion 53, 353 in embodiments 1 and 3, the different diameter portion may have an inner diameter smaller than that of the base diameter portion. In this case, the inner diameter of the variable diameter portion increases from the different diameter portion toward the base diameter portion. Alternatively, like the large diameter portion 253 in embodiment 2, the different diameter portion may have an inner diameter larger than that of the base diameter portion. In this case, the inner diameter of the variable diameter portion decreases from the different diameter portion toward the base diameter portion.

[0069] In the present invention, the tube 50 may have a portion where the inner diameter changes (a diameter changing portion). The diameter changing portion may be disposed at any position relative to the connector 10.

[0070] For example, the inner diameter of the tube 50 may change within the connector 10, as in the diameter changing section 54, 254 of the first and second embodiments. In this case, the inner diameter of the tube 50 (and also the outer diameter of the tube 50) can be kept constant outside the connector 10. With this configuration, portions where the strength of the tube 50 is locally reduced (low-strength portions) are unlikely to occur outside the connector 10. Generally, low-strength portions are prone to kinking, in which the tube 50 bends and the flow path 59 is blocked. In the first and second embodiments, kinking of the tube 50 is unlikely to occur. Alternatively, the inner diameter of the tube 50 may change outside the connector 10, as in the diameter changing section 354 of the third embodiment.

[0071] In the present invention, the inner diameter of the tube 50 may vary within the tubular member 21 of the connector 10. However, preferably, the inner diameter of the tube 50 is constant within the tubular member 21, as in the first to third embodiments.

[0072] In the present invention, the outer diameter of the tube may remain constant along the length of the tube, with only the inner diameter changing. However, preferably, the outer diameter of the tube changes in response to the change in the inner diameter of the tube. That is, it is preferable that the base diameter section and the reduced diameter section each have constant inner and outer diameters along the length of the tube 50, and it is preferable that the reduced diameter section has inner and outer diameters different from those of the base diameter section. In the diameter changing section, it is preferable that both the inner and outer diameters of the tube change so as to expand or contract from the base diameter section to the reduced diameter section. Tubes with both varying inner and outer diameters are generally easier to manufacture than tubes with only varying inner diameters.

[0073] In the present invention, the portion of the tube 50 where the outer diameter changes (diameter changing portion) can be located at any position relative to the connector 10. However, as in embodiments 1 to 3, the outer diameter of the tube 50 is preferably constant within the tubular member 21. This makes it possible to prevent the wall thickness (radial dimension) of the tubular member 21 from changing suddenly in the axial direction. This is advantageous for improving the molding accuracy of the tubular member 21 (particularly the male tapered surface 23).

[0074] In the present invention, it is sufficient that the base end surface 51 of the tube 50 is exposed at the tip of the tubular member 21 of the connector. That is, the base end surface 51 of the tube 50 may protrude in the axial direction from the tip of the tubular member 21, or may be recessed from the tip of the tubular member 21 into the tubular member 21. This is because if the base end surface 51 is exposed, light from the light source 78 can be incident on the base end surface 51. However, preferably, as in the above-mentioned embodiments 1 to 3, the base end surface 51 of the tube 50 forms a common plane with the tip of the tubular member 21. This is advantageous for ensuring compatibility with conventional connectors.

[0075] The connector of the present invention does not need to include the connecting pipe 30. In this case, the axial dimension (total length) of the connector is shortened, allowing the connector to be made more compact. However, as in the above-mentioned embodiments 1 to 3, the connector preferably includes the connecting pipe 30 coaxial with the tubular member 21, and the tube 50 is led out from the connecting pipe 30. The connecting pipe 30 has the following effects. First, the connecting pipe 30 can be used to adhesively fix the tube to the connector. Second, since the operator can grasp the connector by the connecting pipe 30 separated from the tubular member 21, contamination of the tubular member 21 by the operator's fingers, etc., can be prevented.

[0076] The configuration of the connector portion 20 is not limited to the above-described embodiments 1 to 3. For example, it is not essential that the male tapered surface 23 and the tip tapered surface 24 are provided on the outer peripheral surface of the tubular member 21. The tip tapered surface 24 may be omitted, and the male tapered surface 23 may be extended to the tip of the tubular member 21. In this case, the outer diameter of the base end surface 51 of the tube 50 can be increased. This is advantageous in improving the brightness (luminous flux) of the tip 55 of the tube 50 because the area of the base end surface 51 is enlarged and, as a result, more light is incident on the base end surface 51.

[0077] The connector portion 20 does not necessarily have to include the outer cylinder 27 provided with the female thread 28 and the flange 26 .

[0078] The connection structure between the connector and the light source device of the present invention is not limited to the above embodiment. In the above embodiment, the base end surface 51 of the tube 50 is spaced from the light source 78 (see FIG. 3 ). However, the tubular member 21 or the base end surface 51 may be in direct contact with the light source 78. In this case, the stepped surface 73 can be omitted. In the above embodiment, the retaining tube 72 of the light source device 70 is configured so that the outer tube 27 is fitted into the retaining tube 72. However, the present invention is not limited to this. For example, the retaining tube 72 may be configured so that the retaining tube 72 is inserted between the outer tube 27 and the tubular member 21. In this case, the tubular member 21 may be fitted into the retaining tube 72. The inner circumferential surface of the retaining tube 72 may be provided with a tapered surface (female tapered surface) that is tapered and fits with the male tapered surface 23 of the tubular member 21. The outer circumferential surface of the retaining tube 72 may be provided with a male thread that is threadedly engaged with the female thread 28. The light source device does not necessarily have to include the retaining tube 72 into which the outer tube 27 or the tubular member 21 is fitted. In this case, the connector can be connected to the light source device with the tip of the outer tube 27 abutting against a flat surface provided on the light source device that is equivalent to the stepped surface 73. The flat surface positions the connector (or the tube member 21) at a predetermined axial distance from the light source 78. A light source device that does not include a retaining tube 72 has a simple structure and is easy to manufacture. There are no limitations on the method for maintaining the connection state of the connector to the light source device, and any method can be selected, such as using an elastic band or using magnetic attraction.

[0079] Although the catheters 1 to 3 in the above-described embodiments 1 to 3 are used for nasogastric tube feeding, the use of the catheter of the present invention is not limited to this. The catheter of the present invention may be, for example, a catheter used for tube feeding other than nasogastric tube feeding, or a catheter used for purposes other than tube feeding (e.g., a urethral catheter or a tracheal intubation catheter). The configuration of the connector and tube may be modified as appropriate depending on the use of the catheter. The connector of the present invention does not need to be a male connector and may be a female connector. In this case, the tubular member functions as a female member, and any male member is inserted into or removed from the flow path 59 of the tube 50. [Industrial Applicability]

[0080] The present invention can be widely used as a medical catheter for insertion into a patient. [Explanation of symbols]

[0081] 1,2,3 Catheter (medical catheter) 10 Connectors 11 Through hole 21 Cylinder member 27 Outer cylinder 28 Female thread 30 base tube 50 tube (light-conducting tube) 51 Tube base end surface 52,252,352 Base diameter part 53,353 Small diameter section (different diameter section) 253 Large diameter part (different diameter part) 54,254,354 Diameter change section 55 Tube tip

Claims

1. A medical catheter comprising a flexible hollow light-guiding tube and a connector provided at a base end of the light-guiding tube, The connector includes a hollow cylindrical member, the light-guiding tube is inserted into the connector so that a base end surface of the light-guiding tube is exposed at a tip end of the cylindrical member, the light-guiding tube has a base portion having a constant inner diameter outside the connector, A medical catheter, characterized in that the inner diameter of the light-guiding tube at the base end surface is different from the inner diameter of the base portion.

2. 2. The medical catheter according to claim 1, wherein the light-guiding tube further comprises a different diameter portion extending from the base end surface and having a constant inner diameter, and a diameter-changing portion whose inner diameter changes between the base diameter portion and the different diameter portion.

3. 3. The medical catheter according to claim 1, wherein the inner diameter of the light-guiding tube changes within the connector.

4. 3. The medical catheter according to claim 1, wherein the inner diameter of the light-guiding tube is changed outside the connector.

5. 5. The medical catheter according to claim 1, wherein the outer diameter of the light-guiding tube is constant within the cylindrical member.

6. 6. The medical catheter according to claim 1, wherein the base end surface of the light-guiding tube forms a common plane with the tip end of the tubular member.

7. The connector further includes a hollow cylindrical base pipe arranged coaxially with the tubular member, 7. The medical catheter according to claim 1, wherein the light-guiding tube is led out from the connecting pipe.

8. The medical catheter according to any one of claims 1 to 7, wherein the connector further comprises an outer tube surrounding the tubular member, and a female thread provided on an inner circumferential surface of the outer tube facing the tubular member.

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