JP7699337B2 - Medical Catheters - Google Patents

Description

The present invention relates to a medical catheter in which a connector is provided at the base end of a light-conducting tube.

In the medical field, flexible hollow tubes are sometimes inserted into patients for examinations or treatments. For example, tube feeding is used to supply liquid nutrients from the outside to patients who have difficulty chewing or swallowing, in which nutrients are sent directly to the stomach through a tube inserted through the mouth or nose. When using tube feeding, it is necessary to confirm that the tip of the tube is located inside the stomach before sending the nutrients.

Patent Document 1 describes a system for detecting the tip position of a medical tube, in which the tube itself is used as a light guide. Specifically, while the tube is inserted into a patient, light is made to enter the base end surface of the tube and is emitted from the tip of the tube. The position of the tube tip is confirmed by observing this light from outside the body.

WO2021/024992A1 JP 2015-119837 A

In tube feeding, a connector must be provided at the base end of the tube to create a flow path for the nutrients to flow from the container in which they are stored to the stomach. It is desirable for the connector to be compatible with connectors used in conventional tube feeding.

In Patent Document 1, the base end surface of the tube where light is incident is disposed 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 low freedom of choice in terms of tube diameter.

The present invention aims to improve the freedom of choice regarding the diameter of a tube in a medical catheter having a connector at the base end of a light-conducting tube while ensuring compatibility with conventional connectors.

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.

In the present invention, it is possible to set the inner diameter of the base end surface of the light-conducting tube to the same diameter as the tip opening diameter of the conventional connector, while allowing the inner diameter of the base portion to be selected as desired. Therefore, according to the present invention, it is possible to improve the freedom of selection of the tube diameter while ensuring compatibility with conventional connectors.

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. FIG. 2A is a perspective view of a proximal end portion of a medical catheter according to a first embodiment of the present invention. FIG. 2B is a cross-sectional view of the base end portion of the medical catheter according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of a proximal end portion of the medical catheter according to the first embodiment of the present invention connected to a light source device. FIG. 4 is a cross-sectional view of a proximal end portion of a medical catheter according to a second embodiment of the present invention. FIG. 5 is a cross-sectional view of a proximal end portion of a medical catheter according to a third embodiment of the present invention.

In one aspect of the present invention, the light-guiding tube may further include a different diameter section that extends from the base end surface and has a constant inner diameter, and a diameter-changing section whose inner diameter changes between the base diameter section and the different diameter section. Such a tube can be manufactured relatively easily.

In one aspect of the present invention, the inner diameter of the light-guiding tube may vary within the connector. According to this aspect, it is possible to make the strength of the tube substantially constant in its longitudinal direction outside the connector. This is advantageous in preventing the occurrence of kinks in the tube that block the flow path due to bending.

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

In one aspect of the present invention, the outer diameter of the light-guiding tube may be constant within the tubular member. This aspect is advantageous for improving the molding precision of the tubular member (particularly its outer circumferential surface).

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

In one aspect of the present invention, the connector may further include a hollow cylindrical base tube arranged coaxially with the tubular member. The light-conducting tube may be led out from the base tube. According to this aspect, firstly, the base tube can be used to adhesively fix the tube to the connector, and secondly, the surgeon can grasp the connector with the base tube, thereby preventing contamination of the tubular member by the surgeon's fingers, etc.

In one aspect of the present invention, the connector may further include an outer tube that surrounds the tubular member, and a female screw provided on the inner peripheral surface of the outer tube that faces 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 base end of a conventional nasogastric tube used in tube feeding.

The present invention will be described in detail below, showing preferred embodiments. However, it goes without saying that the present invention is not limited to the following embodiments. Each figure referred to in the following description shows a simplified view of the main components constituting the embodiment of the present invention for the convenience of explanation. Therefore, the present invention may include any components not shown in the following figures. Furthermore, within the scope of the present invention, each component shown in the following figures may be modified or omitted. In the drawings cited in the description of each embodiment, components corresponding to components shown in the drawings cited in the preceding embodiment are given the same reference numerals as those in the drawings of the preceding embodiment. For such components, duplicated explanations are omitted, and the explanations of the preceding embodiment should be taken into consideration as appropriate.

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 contained in the member and/or coincides with the central axis of a cylinder or cone (taper) contained 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."

(Embodiment 1)
An embodiment in which the present invention is 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 the 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 provided at the base end of the tube 50. The tube 50 is inserted from the nasal cavity of a patient 90, and a tip 55 of the tube 50 reaches a stomach 91. The tube 50 has flexibility that allows it to be freely curved and deformed. The tube 50 is a hollow cylindrical object in which a continuous flow path 59 (see FIG. 2B described later) is formed over its entire length. The flow path 59 communicates with the outside world of the tube 50 at both ends in the longitudinal direction of the tube 50 (i.e., the base end and the tip 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 light emission on the body surface of the patient 90.

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 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 base end 30. The connector portion 20 has a tubular member (male member in this embodiment 1) 21 having a hollow tubular shape and an outer tube 27 surrounding the tubular member 21. The base tube 30 has a hollow tubular shape. The connector portion 20 (or the tubular member 21) and the base tube 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 base tube 30. The inner diameter of the through hole 11 changes in the connector 10 so that the inner diameter at the tip of the tubular member 21 (the upper end of the tubular member 21 in Figs. 2A and 2B) is smaller than the inner diameter at the tip of the base pipe 30 (the lower end of the base pipe 30 in Figs. 2A and 2B). Specifically, the base pipe 30 has an inner diameter change section 14 in which the inner diameter of the through hole 11 changes in a substantially tapered (or substantially conical) shape. The through hole 11 includes a small inner diameter section 13 having a relatively small and constant inner diameter on the tip side (tubular member 21 side) of the connector 10 relative to the inner diameter change section 14, and includes a reference inner diameter section 12 having a relatively large and constant inner diameter on the base side (base pipe 30 side) of the connector 10 relative to the inner diameter change section 14.

The outer peripheral surface of the tubular member 21 is provided with a male taper 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 taper surface 24, which is located further toward the tip side than the male taper surface 23 and has a larger taper angle than the male taper surface 23. The tip of the tubular member 21 (part or all of the tip taper 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 the connector portion 20) to a female connector (not shown; see, for example, Figures 5A and 5B of Patent Document 2).

A flange 26 protrudes radially outward from the base end of the tubular member 21. An outer tube 27 extends from the circular outer periphery of the flange 26 toward the same side as the tubular member 21 (the tip side of the connector 10). The outer tube 27 has a generally cylindrical shape and is arranged coaxially with the tubular member 21. The outer tube 27 is spaced radially from the tubular member 21. A female thread 28 is provided on the inner circumferential surface of the outer tube 27 facing the tubular member 21.

It is preferable that the connector portion 20 is configured to be compatible with male connectors used in tube feeding (see, for example, Figures 4A and 4B of Patent Document 2).

The material of the connector 10 is not limited, but is preferably made of a material that has a degree of mechanical strength (rigidity) that does not substantially deform 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 molded as a single component by injection molding or the like using the above resin materials.

A flexible hollow tube 50 is inserted into the through hole 11 of the connector 10. The inner cavity of the tube 50, which is continuous over the entire length of the tube 50 (see FIG. 1), constitutes a flow path 59 of the tube 50 (and also of 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 over the entire length of the tube 50. Specifically, the tube 50 has a base diameter section 52, a diameter change section 54, and a small diameter section (different diameter section) 53 in this order from the tip 55 (see FIG. 1) side to the base end side. 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 change section 54, the diameter (inner diameter and outer diameter) changes to a generally tapered shape (or a generally conical surface shape) due to the difference in diameter between the base diameter section 52 and the small diameter section 53.

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

The tube 50 is preferably constructed as a continuous part made of the same material over the entire length of the tube 50 from the end surface (base end surface) 51 on the base end side to the tip 55 (see FIG. 1). Of the entire length of the tube 50, most of the tip 55 side is a base diameter section 52 having a constant diameter (inner diameter and outer diameter). A diameter change section 54 and a small diameter section 53 having a diameter different from that of the base diameter section 52 are provided in the base end vicinity of the tube 50. There is no limitation on the method of forming the section with a different diameter in the tube 50. As an example, a hot molding method can be used in which a base end vicinity section of a tube having a constant diameter (for example, the same diameter as the base diameter section 52) cut to a predetermined length is molded into a predetermined shape using a heated mold, and then immediately quenched. As another example, a method similar to blow molding can be used in which the heated and melted tube material is continuously extruded into a tube shape from a nozzle, while blowing air into the inside of the tube to expand it so that it adheres closely to the inner surface of a mold of a predetermined shape.

The tube 50, which has the base diameter portion 52, the diameter change 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 at the front. The small inner diameter portion 53, the diameter change portion 54, and the base diameter portion 52 of the tube 50 are respectively fitted into the small inner diameter portion 13, the inner diameter change portion 14, and the reference inner diameter portion 12 of the connector 10. 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 be separated from the connector 10. The tube 50 is led out from the base pipe 30 toward the opposite side to 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 world.

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 multi-layer structure having at least an inner layer with a high refractive index and an outer layer with a low refractive index.

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

Figure 3 is a cross-sectional view of the catheter 1 connected to the light source device 70. The light source device 70 includes a holding section 71 that houses and holds the connector 10 (particularly the connector section 20), and a light source 78 that is arranged at a position deeper than the holding section 71. The holding section 71 includes a holding tube 72 and a step surface 73. The inner peripheral surface of the holding tube 72 is a cylindrical surface having approximately the same diameter as the outer tube 27. The step 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 peripheral surface of the holding tube 72. The light source 78 is arranged coaxially with the holding section 71 (or the holding tube 72). The connector 10 (or the connector section 20) is inserted into the holding section 71 until the tip of the outer tube 27 abuts against the step surface 73. The holding tube 72 positions the connector 10 (or the tube member 21) coaxially with the light source 78. The stepped surface 73 positions the connector 10 (or the tubular member 21) at a predetermined axial distance from the light source 78. The tip of the tubular member 21 (or the base end surface 51 of the tube 50) faces the light source 78.

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

As the light source 78, a light emitting diode (LED) can be used, but is not limited to it. The light emitted by the light source 78 is preferably visible light or near infrared light, and the wavelength of the light is not limited to it, but is preferably 360 nm or more, further 630 nm or more, and 3000 nm or less, further 780 nm or less. Light with a wavelength in this range has a high transmittance to the human body, is less invasive to the human body, and is highly safe. Visible light can be observed with the naked eye, so that the position of the tip 55 of the tube 50 can be easily confirmed. Near infrared light has better translucency than visible light, and can be observed through 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. In order to efficiently enter the base end surface 51 of the tube 50 with the light source 78, 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).

The method of using the catheter 1 of this embodiment 1 will be explained.

A catheter 1 is prepared with a connector 10 attached to the base end of a tube 50. As with a typical nasal catheter, the tube 50 is inserted into the nasal cavity of a patient 90 (see FIG. 1). The connector 10 is connected to a light source device 70, and the light source 78 (see FIG. 3) is turned on. The light emitted from the light source 78 enters the base 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.

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

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, the tip of the optical fiber is also illuminated in addition to the tip 55. 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.

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. The connector 10 is then 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 that carries the nutritional supplement (generally called a tube feeding set). 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.

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 the light source device 70, and the tip 55 is illuminated to confirm its position.

As described above, in this embodiment 1, 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.

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 tube-based 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 manner as connecting an existing male connector to the female connector.

There may be standards for shapes and the like for existing male connectors. In order 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 this embodiment 1, 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 at the small diameter portion 53 of the tube 50. If the inner diameter of the small diameter portion 53 that determines the tip opening diameter of the flow path 59 is made the same as the tip opening diameter of the flow path of the existing male connector, compatibility with the existing male connector can be ensured with respect to the tip opening diameter. The base diameter portion 52, which occupies most of the entire 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 this embodiment 1 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 that has a desired constant diameter over its entire length and has a small diameter section 53 and a diameter-changing section 54 formed near the base end so that the small diameter section 53 has the same inner diameter as the tip opening diameter of an existing male connector, compatibility with the existing male connector can be ensured.

In this embodiment 1, the base diameter portion 52 of the tube 50 has an inner diameter larger than the tip opening diameter 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 flowing through the flow path 59.

(Embodiment 2)
4 is a cross-sectional view of a base 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 base 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 base end portion of the tube 50.

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

The tube 50 has, from the tip 55 (see FIG. 1) side toward the base end side, a base diameter section 252, a diameter change section 254, and a large diameter section (different diameter section) 253, in that order. The diameters (inner diameter and outer diameter) of the base diameter section 252 and the large diameter section 253 are constant in the longitudinal direction of the tube 50, but the large diameter section 253 has a larger diameter than the base diameter section 252. In the diameter change section 254, the diameters (inner diameter and outer diameter) change in an approximately tapered shape (or approximately conical surface shape) due to the difference in diameter between the base diameter section 252 and the large diameter section 253.

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 tip side (the cylindrical member 21 side) of the connector 10 with the tip side (the base diameter portion 252 side) of the tube 50 at the head. The large inner diameter portion 253, the diameter change portion 254, and the base diameter portion 252 of the tube 50 are fitted into the large inner diameter portion 213, the inner diameter change portion 214, and the reference 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 base pipe 30) by 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 from the base pipe 30 toward the opposite side to the cylindrical member 21. The base end surface 51 of the tube 50 is flush with the tip of the tubular member 21 (the tip of the tip tapered surface 24) and is exposed to the outside world.

Catheter 2 can be used in the same manner as catheter 1 of embodiment 1.

As in the first embodiment, in the second embodiment, if the inner diameter of the large diameter portion 253 that defines the tip opening diameter of the flow path 59 is made the same as the tip opening diameter of the flow path of the existing male connector, compatibility with the existing male connector can be ensured with respect to the tip opening diameter. The base diameter portion 252, which occupies most of the entire length of the tube 50, may have an inner diameter different from the tip opening diameter, i.e., the large diameter portion 253. Therefore, the catheter 2 can improve the freedom of selection of the diameter of the tube 50 while ensuring compatibility with the existing male connector. For example, if a tube 50 is used in which the large diameter portion 253 and the diameter change portion 254 are formed so that the large diameter portion 253 has the same inner diameter as the tip opening diameter of the existing male connector in the proximal portion of the tube having a desired constant diameter over the entire length, compatibility with the existing male connector can be ensured.

In this 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 diameter base diameter portion 252 is useful, for example, as a nasal catheter for children.

The base end surface 51, into 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.

This embodiment 2 is the same as embodiment 1 except for the above. The explanation of embodiment 1 also applies to this embodiment 2.

(Embodiment 3)
5 is a cross-sectional view of a base end portion of a catheter 3 according to a third embodiment of the present invention. As with 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 base 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 base end portion of the tube 50.

The inner diameter of the through hole 11 of the connector 10 is constant throughout the entire length of the through hole 11.

As in the first embodiment, the tube 50 includes, from the tip 55 (see FIG. 1) side toward the base end side, a base diameter section 352, a diameter change section 354, and a small diameter section (different diameter section) 353, in that order. 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 change section 354, the diameters (inner diameter and outer diameter) change in an approximately tapered shape (or approximately conical surface shape) due to the difference in diameter between the base diameter section 352 and the small diameter section 353.

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 base 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 gaps over the entire length of the through hole 11. The tube 50 is fixed to the connector 10 (particularly the base pipe 30) by 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 base pipe 30 toward the opposite side to the tubular member 21. The diameter change portion 354 is disposed outside the connector 10 and in the vicinity of the connector 10 (particularly the base pipe 30). The base end surface 51 of the tube 50 is flush with the tip of the tubular member 21 (the tip of the tip tapered surface 24) and is exposed to the outside world.

The catheter 3 can be used in the same manner as the catheter 1 of embodiment 1.

As in the first embodiment, in the third embodiment, if the inner diameter of the small diameter portion 353 that defines the tip opening diameter of the flow path 59 is made the same as the tip opening diameter of the flow path of the existing male connector, compatibility with the existing male connector can be ensured with respect to the tip opening diameter. The base diameter portion 352, which occupies most of the entire length of the tube 50, may have an inner diameter different from the tip opening diameter, i.e., the small diameter portion 353. Therefore, the catheter 3 can improve the freedom of selection of the diameter of the tube 50 while ensuring compatibility with the existing male connector. For example, if a tube 50 is used in which the small diameter portion 353 and the diameter change portion 354 are formed so that the small diameter portion 353 has the same inner diameter as the tip opening diameter of the existing male connector in the portion near the base end of the tube having a desired constant diameter over the entire length, compatibility with the existing male connector can be ensured.

In this embodiment 3, the base diameter portion 352 of the tube 50 has an inner diameter larger than the tip opening diameter 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 flowing through the flow path 59.

Unlike the first and second embodiments, the diameter (inner and outer diameter) of the tube 50 varies 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. Therefore, the shape of the connector 10 is simple. This is advantageous in simplifying the mold shape and facilitating the manufacture of the connector 10 when manufacturing the connector 10 by injection molding.

In the third embodiment, the diameter change section 354, which changes the diameter of the tube 50, is located near the connector 10. In this configuration, the ratio of the base diameter section 352 to the total length of the tube 50 increases. In a catheter, the length of the part of the tube having a predetermined and constant outer diameter (the base diameter section 352 in the third embodiment) is generally standardized, so by arranging the diameter change section 354 near the connector 10, it is possible to prevent the total length of the tube from being unnecessarily long. If the tube is too long, problems 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 may occur. In the third embodiment, these problems are less likely to occur. In general, the distance between the connector 10 and the diameter change section 354 is not limited, but is preferably 200 mm or less, further 100 mm or less, and particularly 50 mm or less. However, in the present invention, the position of the diameter change section 354 is arbitrary, and for example, the diameter change section 354 may be located near the tip 55 of the tube 50 (see FIG. 1). In this case, the portion from the connector 10 to the diameter change section 354 is made up of a small diameter section 353 with a constant diameter.

In this embodiment 3, the base diameter portion 352 has a diameter (inner diameter and outer diameter) larger than the tip opening diameter, but the present invention is not limited to this, and the base diameter portion 352 may have a diameter (inner diameter and outer diameter) smaller than the tip opening diameter, similar to the tube 50 constituting the catheter 2 of embodiment 2. Such a catheter is useful as a nasal catheter for children with improved brightness of the tip 55, similar to the catheter 2 of embodiment 2.

This embodiment 3 is the same as embodiment 1 except for the above. The explanation of embodiment 1 also applies to this embodiment 3.

The above embodiments 1 to 3 are merely examples. The present invention is not limited to the above embodiments 1 to 3 and can be modified as appropriate.

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 is no restriction on the arrangement of the base portion relative to the connector 10. For example, as in embodiments 1 and 2, a part 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.

In the present invention, the base portion occupies the majority of the overall length of the tube 50. Specifically, the length of the base portion is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more of the overall length of the tube 50.

In the present invention, the inner diameter of the tube may change 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 diameter change portion whose inner diameter changes 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, the different diameter portion may have an inner diameter smaller than the base diameter portion, as in the small diameter portion 53, 353 of embodiments 1 and 3. In this case, the inner diameter of the diameter change portion increases from the different diameter portion toward the base diameter portion. Alternatively, the different diameter portion may have an inner diameter larger than the base diameter portion, as in the large diameter portion 253 of embodiment 2. In this case, the inner diameter of the diameter change portion decreases from the different diameter portion toward the base diameter portion.

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

For example, the inner diameter of the tube 50 may change inside 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 constant outside the connector 10. In this configuration, a portion (low-strength portion) where the strength of the tube 50 is locally reduced is unlikely to occur outside the connector 10. Generally, in a low-strength portion, kinking, in which the tube 50 bends and the flow path 59 is blocked, is likely to occur. 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.

In the present invention, the inner diameter of the tube 50 may vary within the tubular member 21 of the connector 10. However, preferably, as in embodiments 1 to 3, the inner diameter of the tube 50 is constant within the tubular member 21.

In the present invention, the outer diameter of the tube may remain constant in the longitudinal direction 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 each of the base diameter section and the different diameter section has a constant inner diameter and outer diameter in the longitudinal direction of the tube 50, and it is preferable that the different diameter section has an inner diameter and outer diameter different from the base diameter section. In the diameter changing section, it is preferable that both the inner diameter and the outer diameter of the tube change so as to expand or contract from the base diameter section toward the different diameter section. A tube in which both the inner diameter and the outer diameter change is generally easier to manufacture than a tube in which only the inner diameter changes.

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 taper surface 23).

In the present invention, the base end surface 51 of the tube 50 may be 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 recede from the tip of the tubular member 21 into the tubular member 21. 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 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.

The connector of the present invention does not have to include the connecting pipe 30. In this case, the axial dimension (total length) of the connector is shortened, and the connector can be made smaller. However, as in the above embodiments 1 to 3, the connector preferably includes a 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, the operator can grasp the connector by the connecting pipe 30 separated from the tubular member 21, which prevents contamination of the tubular member 21 by the operator's fingers, etc.

The configuration of the connector portion 20 is not limited to the above 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 enlarged. This is advantageous for improving the brightness (luminous flux) of the tip 55 of the tube 50, since the area of the base end surface 51 is enlarged, thereby increasing the amount of light incident on the base end surface 51.

The connector portion 20 does not have to include an outer tube 27 and a flange 26 with a female thread 28.

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 separated from the light source 78 (see FIG. 3), but the tubular member 21 or the base end surface 51 may be in direct contact with the light source 78. In this case, the step 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 fits into the retaining tube 72, but 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, for example, the tubular member 21 may be fitted into the retaining tube 72. The inner peripheral surface of the retaining tube 72 may be provided with a tapered surface (female tapered surface) that tapers and fits with the male tapered surface 23 of the tubular member 21. The outer peripheral surface of the retaining tube 72 may be provided with a male thread that screws into the female thread 28. The light source device may not have a 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 equivalent to the stepped surface 73 provided on the light source device. 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 have a retaining tube 72 has a simple structure and is easy to manufacture. There are no limitations on the method of maintaining the connection state of the connector to the light source device, and any method can be selected, such as a method using an elastic band or a method using magnetic attraction.

Although the catheters 1 to 3 in the above 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 changed 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 cylindrical member functions as a female member, and any male member is inserted and removed from the flow path 59 of the tube 50.

The present invention can be used widely as a medical catheter for insertion into a patient.

1, 2, 3 Catheter (medical catheter)
10 Connector 11 Through hole 21 Cylinder member 27 Outer cylinder 28 Female screw 30 Tube 50 Tube (light-guiding tube)
51: Base end surface of tube 52, 252, 352: Base diameter portion 53, 353: Small diameter portion (different diameter portion)
253 Large diameter section (different diameter section)
54, 254, 354 Diameter change section 55 Tube tip

Claims (4)

A medical catheter comprising a flexible hollow light-guiding tube and a connector provided on the light-guiding tube ,
The light-guiding tube has a base end at one end and a tip end at the other end,
the light-guiding tube includes a different diameter portion extending from a base end surface that is an end surface on the base end side and having a constant inner diameter, a base diameter portion disposed on the tip side and having a constant inner diameter different from that of the different diameter portion, and a diameter changing portion whose inner diameter changes between the different diameter portion and the base diameter portion,
The connector includes a hollow cylindrical member having a tip at one end thereof and a hollow cylindrical base pipe at the other end thereof, the cylindrical member and the base pipe being coaxially arranged,
the base end of the light-guiding tube is inserted into the connector such that the base end surface of the light-guiding tube is exposed to the tip of the tubular member,
A medical catheter, characterized in that the different diameter portion, the diameter changing portion and a part of the base diameter portion of the light-guiding tube are housed within the connector, and the remainder of the base diameter portion is led out from the base pipe . 2. The medical catheter according to claim 1 , wherein the outer diameter of the light-guiding tube is constant within the tubular member. 3. 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. The medical catheter according to any one of claims 1 to 3 , wherein the connector further comprises an outer tube surrounding the tubular member, and a female screw provided on an inner circumferential surface of the outer tube facing the tubular member.