Catheter visualization device and medical catheter set

Abstract

Provided are: a catheter visualization device capable of emitting light at a high output from a tip portion of an optical fiber; and a medical catheter set provided with the same.　A catheter visualization device 2 makes it possible to visually recognize the tip position of a catheter 3 and is provided with: an optical fiber 10 that comprises a core 11 centrally positioned in the radial direction and a clad 12 positioned on the outer circumferential side of the core 11, and that has a base portion 10b and a tip portion 10t; and a light source 20 that causes light to enter the optical fiber 10 from the base portion 10b. Between the base portion 10b and the tip portion 10t, the optical fiber 10 is provided with a tapered portion 10T having a shape in which the core 11 is tapered toward a tip portion side t. A medical catheter set 1 is provided with said catheter visualization device 2 and the catheter 3.

Description

Catheter visualization device and medical catheter set

[0001] The present invention relates to a catheter visualization device and a medical catheter set including the same.

[0002] In medical settings, for patients who have difficulty taking food and drink orally, a catheter has been inserted through the patient's nasal cavity, and the tip of the catheter has been extended to the stomach to directly supply food and drink, such as liquid food and nutritional supplements. In this case, as a means for grasping the position of the catheter tip, a catheter visualization device has been proposed that is inserted into the body together with the catheter and projects the tip of the catheter onto the body surface from inside the body in order to visualize the catheter tip (see, for example, Patent Document 1).

[0003] Fig. 8 is a schematic diagram showing an example of a medical catheter set including a conventional catheter visualization device and a catheter. As shown in Fig. 8, a conventional medical catheter set 101 includes a catheter visualization device 102 and a catheter 103.

[0004] The catheter visualization device 102 includes an optical fiber 110 having a core 111 located radially toward the center and a cladding 112 located on the outer periphery of the core 111, and a light source 120 such as an LED (light-emitting diode) or a laser. The light source 120 includes a light source main body 121 and a light-emitting unit 122 that emits light.

[0005] In the catheter visualization device 102, the optical fiber 110 and the light source 120 are connected by a connector 130. Specifically, a locking protrusion 123 provided on the light source main body 121 is fitted into a locking hole 133 formed in the connector 130, thereby locking and fixing the two together. The light emitting surface 122p of the light emitting unit 122 is arranged so as to face the base end surface 110b' of the base end 110b of the optical fiber 110. The optical fiber 110 is inserted into the catheter 103, and the tip end 110t is located at or near the tip end 103t of the catheter 103.

[0006] The catheter visualization device 102 causes light to be incident from a light source 120 onto a base end surface 110b' of a base end portion 110b of the optical fiber 110, and emits the light from a tip end surface 110t' of a tip end 110t of the optical fiber 110. The light emitted from the tip end surface 110t' of the tip end 110t of the optical fiber 110 is projected onto the body surface from inside the body, thereby making it possible to visually confirm the position of the tip end 103t of the catheter 103 from outside the body.

[0007] Re-table 2019 / 215791 publication

[0008] The optical fiber 110 in the catheter visualization device 102 is small in diameter because it is inserted into the catheter 103. Depending on the conditions of the catheter 103 and the patient's condition, it is not uncommon to use an optical fiber 110 with an extremely small outer diameter of 0.5 mm or less. From the viewpoint of safety, it is desirable to use an LED or multimode laser as the light source, which has low beam directivity and low optical power density, but these are difficult to couple to a small-diameter optical fiber. On the other hand, in order to make the projected image from inside the body visible from the body surface, it is necessary for the light emitted from the tip 110t of the optical fiber 110 to be bright enough.

[0009] In order to emit light with sufficient brightness from the tip end 110t of the optical fiber 110, it is necessary to input light of a corresponding power from the base end 110b of the optical fiber 110. On the other hand, when the power of the light source 120 is increased, particularly in an LED device, the area of ​​the light-emitting portion 122 generally increases. Therefore, if the area of ​​the light-emitting portion 122 is larger than that of an optical fiber 110 with a small outer diameter, it becomes difficult to introduce light into the optical fiber 110 from the base end 110b.

[0010] That is, even if a light source 120 with high power and a large area of ​​the light-emitting portion 122 is coupled to the base end 110b of the optical fiber 110 with a small outer diameter, some of the light emitted by the light-emitting portion 122 will not be introduced into the optical fiber 110, resulting in a loss. Therefore, even if the power of the light source is increased, the output of light emitted from the tip end 110t of the optical fiber 110 cannot be sufficiently increased. In order to prevent this loss, a light source 120 with a reduced power and a small area of ​​the light-emitting portion 122 must be used, which makes it difficult to sufficiently increase the output of light emitted from the tip end surface 110t' of the tip end 110t of the optical fiber 110.

[0011] Furthermore, as a result of investigations by the inventors, it has been confirmed that even if a high-output multimode laser or LED is used as the light source 120, a focusing lens is attached to the light-emitting portion 122 with a large area (for example, an emission area of ​​1 mm x 1 mm), and the light is narrowed by the focusing lens and introduced into the base end 110b of the optical fiber 110, almost no light is coupled (with a light source with an output of 170 mW, the output of the light emitted from the tip end 110t of the optical fiber 110 is about 6 mW).

[0012] Therefore, an object of the present invention is to provide a catheter visualization device capable of emitting high-power light from the tip of an optical fiber, and a medical catheter set including the same.

[0013] The above object can be achieved by the present invention, which is described below.

[0014] <1> A catheter visualization device that enables the position of a tip of a catheter to be visualized, comprising: an optical fiber that is made up of a core located radially toward the center and a cladding located on the outer periphery of the core, and that has a base end and a tip end; and a light source that directs light into the optical fiber from the base end, wherein the optical fiber has a tapered portion between the base end and the tip end, where the core has a shape that tapers toward the tip end.

[0015] <2> The catheter visualization device according to <1>, wherein the core in at least the tapered portion is made of quartz.

[0016] <3> The catheter visualization device according to <1>, wherein the optical fiber has the tapered portion, a large diameter portion closer to the base end than the tapered portion, and a small diameter portion closer to the tip end than the tapered portion, and the tapered portion and the large diameter portion or the tapered portion and the small diameter portion are connected by fusion.

[0017] <4> The catheter visualization device according to <1>, wherein the optical fiber has the tapered portion, a large diameter portion closer to the base end than the tapered portion, and a small diameter portion closer to the tip end than the tapered portion, and the numerical aperture (NA) of the large diameter portion of the optical fiber is 0.5 or more.

[0018] <5> The catheter visualization device according to <4>, wherein the large diameter portion of the optical fiber is made of a holey fiber.

[0019] <6> The catheter visualization device according to <1>, wherein the optical fiber has at least the tapered portion and a small diameter portion located closer to the tip portion than the tapered portion, and the small diameter portion of the optical fiber is made of a double-clad fiber.

[0020] <7> The catheter visualization device according to <1>, wherein the diameter of the core at the position of the tapered portion closest to the base end portion is 500 μm or more.

[0021] <8> The catheter visualization device according to <1>, wherein the length of the tapered portion in the longitudinal direction of the optical fiber is 10 mm or more.

[0022] <9> The catheter visualization device according to <1>, further comprising a connector that surrounds and holds the base end of the optical fiber and a side surface in the vicinity thereof so that a base end face of the base end of the optical fiber is disposed opposite to a light emitting surface of the light source, and the tapered portion is located inside the connector.

[0023] <10> The catheter visualization device according to <1>, wherein the light source is an LED that emits visible light.

[0024] <11> A medical catheter set comprising the catheter visualization device according to <1> and a catheter.

[0025] <12> The medical catheter set according to <11>, wherein the optical fiber in the catheter visualization device is inserted into the catheter, and the tip of the optical fiber is located at or near the tip of the catheter.

[0026] According to the present invention, it is possible to provide a catheter visualization device capable of emitting high-power light from the tip of an optical fiber, and a medical catheter set including the same.

[0027] FIG. 1 is a schematic diagram of a medical catheter set including a catheter visualization device according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a tapered portion of an optical fiber and its vicinity in the catheter visualization device according to the first embodiment. FIG. 3 is a schematic diagram of a medical catheter set including a catheter visualization device according to a second embodiment of the present invention. FIG. 4 is a schematic cross-sectional view showing the cross-sectional structure of a large diameter portion of an optical fiber used in the catheter visualization device according to the second embodiment. FIG. 4 is a schematic diagram of a medical catheter set including a catheter visualization device according to a third embodiment of the present invention. FIG. 5 is an enlarged cross-sectional view of a tapered portion of an optical fiber and its vicinity in the catheter visualization device according to the third embodiment. FIG. 6 is an explanatory diagram for explaining a method of designing the taper angle of the tapered portion of the optical fiber in the catheter visualization device according to the third embodiment. FIG. 7 is a schematic diagram showing an example of a medical catheter set including a conventional catheter visualization device and a catheter.

[0028] Hereinafter, catheter visualization devices according to three embodiments, which are exemplary aspects of the present invention, and medical catheter sets including the same will be specifically described with reference to the drawings.

[0029] <First embodiment> Figure 1 is a schematic diagram of a medical catheter set 1 equipped with a catheter visualization device 2 according to a first embodiment. As shown in Figure 1, the medical catheter set 1 includes the catheter visualization device 2 and a catheter 3. In Figure 1, the base end side (proximal end side) of the optical fiber is indicated by arrow b, and the distal end side (proximal end side) is indicated by arrow t (the same applies to the subsequent figures).

[0030] The term "medical catheter set" is a general term referring to a set of a catheter visualization device and a catheter. Therefore, in addition to the state in which the catheter visualization device and catheter are integrated when in use, even if the two are packaged or displayed separately when traded in the market, the term "medical catheter set" includes the two as long as they are associated and set together.

[0031] The catheter visualization device 2 according to this embodiment includes an optical fiber 10 having a core 11 located radially toward the center and a cladding 12 located on the outer periphery of the core 11, and having a base end 10b and a tip end 10t, and a light source 20. The light source 20 includes a light source main body 21 and a light-emitting unit 22 that emits light.

[0032] Examples of light source 20 include an LED (light-emitting diode) and a laser, and there are no limitations as long as it emits visible light, but from the standpoint of safety and cost, it is preferable to use an LED as light source 20. When light source 20 is an LED, the LED chip corresponds to light-emitting unit 22, and a housing equipped with a power supply, various electronic circuits, etc. corresponds to light source main body 21.

[0033] The catheter visualization device 2 according to this embodiment includes a connector 30 that couples the optical fiber 10 and the light source 20. Specifically, a locking protrusion 23 provided on the light source main body 21 is fitted into a locking hole 33 formed in the connector 30, thereby locking and fixing the optical fiber 10 and the light source 20 together. The connector 30 surrounds and holds the proximal end 10b of the optical fiber 10 and the side surface in the vicinity thereof so that the light-emitting surface 22p of the light-emitting unit 22 faces the proximal end face 10b' of the proximal end 10b of the optical fiber 10.

[0034] In this embodiment, the optical fiber 10 has a tapered portion 10T between the base end 10b and the tip end 10t, in which the core 11 tapers toward the tip end side t. The optical fiber 10 also has a large diameter portion 10L on the base end side b from the tapered portion 10T and a small diameter portion 10S on the tip end side t from the tapered portion 10T.

[0035] 2 is an enlarged cross-sectional view of the tapered portion 10T and its vicinity of the optical fiber 10 in the catheter visualization device 2 according to the first embodiment. As shown in Fig. 1 and Fig. 2, the large diameter portion 10L is continuous with the tapered portion 10T at the most proximal end side b, and the small diameter portion 10S is continuous with the tapered portion 10T at the most distal end side t.

[0036] The small diameter portion 10S of the optical fiber 10 is inserted into the catheter 3, and the tip portion 10t is located at or near the tip portion 3t of the catheter 3. Therefore, depending on the thickness of the catheter 3, it may be necessary to reduce the outer diameter of the small diameter portion 10S of the optical fiber 10. For example, in this embodiment, the outer diameter of the catheter 3 is 1.5 mm, and the inner diameter is 1.0 mm. Therefore, it is desirable that the outer diameter D4 of the small diameter portion 10S of the optical fiber 10 be sufficiently smaller than the inner diameter of the catheter 3, and therefore in this embodiment, it is 550 μm, for example, and the diameter D2 of the core 11S at that portion is as small as 500 μm.

[0037] In the tapered portion 10T of the optical fiber 10, the diameter of the core 11T at the tip end side t is 500 μm, which is the same as the diameter D2 of the core 11S, but the diameter gradually increases in a trumpet shape toward the base end side b. The diameter of the core 11T at the position closest to the base end side b is the same as the diameter D1 of the core 11L in the large diameter portion 10L.

[0038] In the longitudinal direction of the optical fiber 10 (the left-right direction in FIG. 2 ), the length L1 of the tapered portion 10T is, for example, 15 mm in this embodiment. The length L1 of the tapered portion 10T is preferably 10 mm or more, and more preferably 12 mm or more. By ensuring a sufficient length L1 of the tapered portion 10T, it is possible to suppress the loss of optical energy.

[0039] That is, the core 11 is formed as an optical path whose diameter gradually changes by connecting a small diameter portion 10S having a very small diameter with a large diameter portion 10L having a larger diameter by a tapered portion 10T. In this embodiment, for example, the outer diameter D3 of the large diameter portion 10L is 1.1 mm, and the diameter D1 of the core 11L at that portion is 1000 μm (1 mm).

[0040] The inclination angle θ of the taper in the core 11T of the tapered portion 10T (the angle between the core 11T and a straight line extending in the longitudinal direction of the optical fiber 10) is preferably about 0.1 to 10°, more preferably about 0.3 to 5°, and even more preferably about 0.5 to 3°. If the inclination angle θ is too large, there is a concern that the loss of light in the tapered portion 10T will be large, while if the inclination angle θ is too small, it may be impossible to achieve the desired diameter for the large diameter portion 10L or the small diameter portion 10S, or the tapered portion 10T will become too long, both of which are undesirable.

[0041] The optical fiber 10 is inserted into the catheter 3, and the tip 10t is located at or near the tip 3t ​​of the catheter 3. The catheter visualization device 2 causes light to be incident from the light source 20 at the proximal end surface 10b' of the proximal end 10b of the optical fiber 10, and emits the light from the distal end surface 10t' of the tip 10t of the optical fiber 10. Therefore, by using the optical fiber 10 in this embodiment, it is possible to form a small diameter portion 10S with an extremely small diameter in the region on the tip side t that is inserted into the catheter 3, and a large diameter portion 10L with a large diameter on the proximal end side b where the light is incident, thereby suppressing loss of light incident from the light emitting surface 22p of the light emitting unit 22 of the light source 20.

[0042] According to the medical catheter set 1 equipped with the catheter visualization device 2 of this embodiment, the position of the tip 3t ​​of the catheter 3 can be visually recognized from outside the body (i.e., the tip position of the catheter 3 can be visually recognized) by projecting light emitted from the tip surface 10t' of the tip 10t of the optical fiber 10 onto the body surface from inside the body.

[0043] In order to enable visible light to be emitted from the tip surface 10t' of the tip portion 10t of the optical fiber 10, part or all of the cladding 12 on the outer surface near the tip portion 10t may be removed, or the tip portion 10t may be cut obliquely, or other known methods may be employed.

[0044] In this embodiment, for example, an LED that emits 120 mW of visible light is used as the light source 20, and the size of the light-emitting unit 22 is 1 mm × 1 mm. Since the diameter D1 of the core 11 (11L) at the base end 10b of the optical fiber 10 facing the light-emitting surface 22p of the light-emitting unit 22 is 1000 μm, most of the light emitted from the light-emitting unit 22 can be introduced into the core 11 of the optical fiber 10. It is desirable to set the distance between the base end surface 10b' of the base end 10b of the optical fiber 10 and the light-emitting surface 22p of the light-emitting unit 22 (the end face of the LED chip) to be close to 1 mm or less.

[0045] According to the results of a simulation conducted by the present inventors, the output power emitted from the distal end surface 10t' of the distal end portion 10t of the optical fiber 10 was 60 mW for an input power of 120 mW, which is extremely efficient when losses at various locations are taken into consideration, and it was confirmed that high-output light emission is possible. In contrast, a similar simulation test was conducted on the conventional catheter visualization device 102 shown in Figure 8. That is, the simulation results were conducted under the same conditions as those of the present embodiment, except that the optical fiber 110 did not have a tapered portion 10T and had the same outer diameter and core 111 diameter along its entire length (outer diameter: 550 μm, core 111 diameter: 500 μm). For an input power of 120 mW, the output power emitted from the distal end 110t of the optical fiber 110 was 30 mW, confirming that the output power was insufficient.

[0046] In the optical fiber 10, both the core 11 and the cladding 12 may be made of resin, but it is preferable that at least the core 11T in the tapered portion 10T is made of quartz, and it is more preferable that the entire core 11 is made of quartz. This is because quartz optical fibers have transmission loss that is two or more orders of magnitude lower than plastic optical fibers and are easier to process. By making at least the core 11T in the tapered portion 10T of quartz, loss can be reduced.

[0047] The numerical aperture (NA) of the large diameter portion 10L of the optical fiber 10 is preferably 0.5 or greater, and more preferably 0.6 or greater. By using an optical fiber 10 with a sufficiently large numerical aperture (NA), it is possible to reduce light loss when introducing light into the base end portion 10b of the optical fiber 10. In this embodiment, the optical fiber 10 used has a numerical aperture (NA) of 0.5 in the large diameter portion 10L.

[0048] The optical fiber 10 used in this embodiment can be manufactured, for example, as follows: A large-diameter optical fiber having a core and a cladding made of the same material, which will become the large-diameter portion 10L, and a small-diameter optical fiber which will become the small-diameter portion 10S, are prepared. In this case, the large-diameter optical fiber is prepared to meet the various dimensions and specifications required for the large-diameter portion 10L, such as the numerical aperture (NA), and the small-diameter optical fiber is prepared to meet the various dimensions and specifications required for the small-diameter portion 10S.

[0049] One end of a small-diameter quartz optical fiber and its vicinity are heated to a temperature of about 2000°C, for example, using laser processing or an electric discharge machine. This causes the end of the optical fiber to expand in a tapered shape, and once it has expanded to the diameter of the large-diameter optical fiber, it is brought into contact with one end of the large-diameter optical fiber and the two are fused together (this is manufacturing method A). Alternatively, one end of a large-diameter quartz optical fiber is drawn while its vicinity is heated to a temperature of about 2000°C, for example. This causes the end of the optical fiber to narrow in a tapered shape, and once it has narrowed to the diameter of the small-diameter optical fiber, it is brought into contact with one end of the small-diameter optical fiber and the two are fused together (this is manufacturing method B).

[0050] In this manner, it is possible to manufacture an optical fiber 10 that includes a small diameter portion 10S made of a small diameter optical fiber, a tapered portion 10T formed by heating a small or large diameter optical fiber, and a large diameter portion 10L made of a large diameter optical fiber. According to the former manufacturing method A, the optical fiber 10 is in a state in which the tapered portion 10T and the large diameter portion 10L are connected by fusion, and according to the latter manufacturing method B, the optical fiber 10 is in a state in which the tapered portion 10T and the small diameter portion 10S are connected by fusion.

[0051] The desired diameter D2 of the core 11S in the small diameter portion 10S is determined automatically based on the inner diameter of the catheter 3 and other conditions, but is preferably 500 μm or less, more preferably 400 μm or less, and even more preferably 300 μm or less. There is no lower limit to the diameter D2 of the core 11S as long as it can emit light with the desired output, but in order to ensure that output, it is preferably 30 μm or more, and more preferably 50 μm or more.

[0052] The diameter of the core 11 at the position closest to the base end B of the tapered portion 10T, in other words, the diameter D1 of the core 11L in the large diameter portion 10L, is determined automatically from conditions such as the size of the light emitting surface 22p of the light emitting portion 122 in the light source 20, but is preferably 500 μm or more, more preferably 800 μm or more, and even more preferably 1000 μm or more. The upper limit of the diameter D1 of the core 11L is preferably 2 mm or less, more preferably 1.5 mm or less, in order to ensure the function as an optical fiber.

[0053] The ratio (D2 / D1) of the diameter D2 of the core 11S in the small diameter portion 10S to the diameter D1 of the core 11L in the large diameter portion 10L is preferably 0.2 or more and 0.95 or less, more preferably 0.3 or more and 0.9 or less, and even more preferably 0.4 or more and 0.8 or less. If the ratio (D2 / D1) is too small, the loss of light in the tapered portion 10T increases, which is undesirable. On the other hand, if the ratio (D2 / D1) is too large, the effect of changing the diameter of the core 11 in the tapered portion 10T decreases, which is undesirable.

[0054] <Second Embodiment> Figure 3 is a schematic diagram of a medical catheter set 1A equipped with a catheter visualization device 2A according to a second embodiment. In Figure 3 showing the medical catheter set 1A equipped with the catheter visualization device 2A according to this embodiment, the same reference numerals are used to designate the same components as those in the medical catheter set 1 to the catheter visualization device 2 according to the first embodiment, and a description of the same configuration of each component will be omitted. Below, differences from the first embodiment will be mainly described.

[0055] The catheter visualization device 2A according to this embodiment includes an optical fiber 10A and a light source 20. In the medical catheter set 1A including the catheter visualization device 2A according to this embodiment, light emitted from the distal end surface 10At' of the distal end 10At of the optical fiber 10A is projected onto the body surface from inside the body, so that the position of the distal end 3t of the catheter 3 can be visually recognized from outside the body (i.e., the distal end position of the catheter 3 can be visually recognized).

[0056] In this embodiment, the optical fiber 10A includes a tapered portion 10AT between the base end 10Ab and the tip end 10At, in which the core 11A tapers toward the tip end side t. The optical fiber 10A also includes a large diameter portion 10AL located closer to the base end side b than the tapered portion 10AT, and a small diameter portion 10AS located closer to the tip end side t than the tapered portion 10AT.

[0057] The catheter visualization device 2A according to this embodiment differs from the optical fiber 10 according to the first embodiment in the structure of the optical fiber 10A. Specifically, the optical fiber 10A according to this embodiment differs from the optical fiber 10 according to the first embodiment in that the large diameter portion 10AL having a high aperture angle NA is made of a holey fiber, and the small diameter portion 10AS is made of a double-clad fiber.

[0058] A holey fiber is an optical fiber having a structure in which cavities called "holes" are provided in the cladding of the optical fiber and are arranged to surround the core. As shown in Fig. 3, in the large diameter portion 10AL of the optical fiber 10A in this embodiment, a plurality of holes 13 extending in the longitudinal direction of the optical fiber 10A (the left-right direction in Fig. 3) are provided in the cladding 12AL.

[0059] The holes 13 are filled with air, which has a low refractive index, and the difference in refractive index between the core 11 and air is large, thereby enhancing the light confinement effect. Therefore, in the optical fiber 10A of this embodiment, the numerical aperture (NA) of the large diameter portion 10L can be increased, making it easier to ensure the preferable numerical aperture (NA) of the large diameter portion 10L described in the first embodiment. Therefore, it is possible to reduce light loss when introducing light into the base end 10Ab of the optical fiber 10A.

[0060] 4 is a schematic cross-sectional view showing the cross-sectional structure of the large-diameter section 10AL, which is a large-diameter holey fiber used in this embodiment. In the large-diameter section 10AL, a plurality of holes 13 are arranged at equal intervals in two layers of circles, one large and one small. In this embodiment, the holes 13 have a hole diameter Dp of 10 μm and a hole spacing S of 15 μm.

[0061] To achieve a sufficient light confinement effect, the holes 13 are arranged in two layers, a first layer 1L on the inner periphery and a second layer 2L on the outer periphery, as shown in FIG. 4 . There are 48 holes 13 in the first layer 1L and 60 holes in the second layer 2L. The core diameter (diameter of the first layer 1L) Dc is approximately 200 μm. The large diameter portion 10AL, which is a holey fiber, has an aperture angle NA of 0.5 or more. The material of the optical fiber 10A may be undoped quartz, but quartz doped with impurities such as germanium (Ge) in the core (inside the first layer 1L) may also be used.

[0062] On the other hand, a double-clad fiber is an optical fiber having a structure in which two cladding layers are formed around the outer periphery of a core. As shown in Figure 3, in the small diameter portion 10AS of the optical fiber 10A in this embodiment, the outer periphery of the core 11AS is covered with a layer of a first cladding 12A-1, and the outer periphery of that is further covered with a layer of a second cladding 12A-2.

[0063] In the small diameter portion 10AS, which is a double-clad fiber, not only the core 11AS, which is closed by the first cladding 12A-1, serves as an optical transmission path, but also the layer of the first cladding 12A-1, which is closed by the second cladding 12A-2, serves as an optical transmission path. In this embodiment, the core diameter is 250 μm, the outer diameter of the first cladding 12A-1 is 300 μm, and the outer diameter of the second cladding is 350 μm. In the small diameter portion 10AS, which is a double-clad fiber, the aperture angle NA of the first cladding 12A-1 is 0.2 or greater.

[0064] When the large diameter portion 10L and the small diameter portion 10AS are connected by fusion, the cores do not completely match at the connection portion, and some light leaks into the clad. However, by using the small diameter portion 10AS as a double-clad fiber, even if light leaks into the first clad 12A-1 that covers the outer periphery of the core 11AS, the first clad 12A-1 becomes a transmission path for the light, and the loss of light due to leakage into the clad 12A can be suppressed.

[0065] 3, the tapered portion 10AT and the small diameter portion 10AS are connected by fusion. Therefore, there is a concern that light transmitted through the core 11AL at the boundary c between the tapered portion 10AT and the small diameter portion 10AS may leak not only to the core 11AS but also to the first cladding 12A-1. However, the first cladding 12A-1 serves as a transmission path without leaking outside the second cladding 12A-2, thereby suppressing light loss.

[0066] Furthermore, when the portions connected by fusion are a tapered portion (referenced "10AT" in the description using FIG. 3; the same applies to reference symbols in parentheses hereinafter) and a large diameter portion (10AL), two layers, namely, a first clad (12A-1) and a second clad (12A-2) derived from the double-clad fiber, are formed in the tapered portion (10AT) formed by widening in a tapered shape from the small diameter portion (10AS). Therefore, at the boundary between the tapered portion (10AT) and the large diameter portion (10AL), there is a concern that light transmitted through the core (11AL) may leak not only to the core (11AS) but also to the first clad (12A-1). However, since the first clad (12A-1) serves as a transmission path without leaking outside the second clad (12A-2), loss of light is suppressed.

[0067] The optical fiber 10A used in this embodiment can be manufactured in the same manner as the manufacturing method described in Embodiment 1. That is, the optical fiber 10A used in this embodiment can be manufactured by using a holey fiber as the large-diameter optical fiber and a double-clad fiber as the small-diameter optical fiber in the manufacturing method described in Embodiment 1.

[0068] According to manufacturing method A described in the first embodiment, the tapered portion 10AT and the large diameter portion 10AL are connected by fusion, and according to manufacturing method B, the tapered portion 10AT and the small diameter portion 10AS are connected by fusion.

[0069] Other structures, materials, specifications, dimensions (including preferred conditions) of the optical fiber 10A in this embodiment are the same as those of the optical fiber 10 in the first embodiment.

[0070] <Third Embodiment> Figure 5 is a schematic diagram of a medical catheter set 1B equipped with a catheter visualization device 2B according to a third embodiment. In Figure 5 showing the medical catheter set 1B equipped with the catheter visualization device 2B according to this embodiment, the same reference numerals as those in the medical catheter set 1 to the catheter visualization device 2 according to the first embodiment are used to designate the same components as those in the medical catheter set 1 to the catheter visualization device 2, and a description of the same components will be omitted. Below, differences from the first embodiment will be mainly described.

[0071] The catheter visualization device 2B according to this embodiment includes an optical fiber 10B and a light source 20. In a medical catheter set 1B including the catheter visualization device 2B according to this embodiment, the position of the tip 3t ​​of the catheter 3 can be visually recognized from outside the body (i.e., the tip position of the catheter 3 can be visually recognized) by projecting light emitted from the tip 10Bt of the optical fiber 10B onto the body surface from inside the body. Here, the optical fiber 10B may be made of plastic. When the optical fiber is plastic, for example, the core is often made of PMMA (polymethyl methacrylate) and the cladding is made of fluororesin. In this case, the refractive index of the core is 1.49 and the refractive index of the cladding is 1.05, for example, and the numerical aperture angle NA is 0.63.

[0072] Similar to the first embodiment, the catheter visualization device 2B according to this embodiment includes a connector 30B that couples the optical fiber 10B with the light source 20. The connector 30B surrounds and holds the proximal end 10Bb of the optical fiber 10B and the side surface in the vicinity thereof so that the light-emitting surface 22p of the light-emitting unit 22 faces the proximal end face 10Bb' of the proximal end 10Bb of the optical fiber 10B.

[0073] In this embodiment, the optical fiber 10B includes a tapered portion 10BT between the base end 10Bb and the tip end 10Bt, in which the core 11B tapers toward the tip end t. The optical fiber 10B also includes a small diameter portion 10BS located closer to the tip end t than the tapered portion 10BT.

[0074] The catheter visualization device 2B according to this embodiment differs from the optical fiber 10 according to the first embodiment in the structure of the optical fiber 10B. Specifically, the optical fiber 10B according to this embodiment does not have an optical fiber that forms the large diameter portion connected to the base end side b of the tapered portion 10BT, and the end of the base end side b of the tapered portion 10BT forms the base end 10Bb of the optical fiber 10B, which is different from the optical fiber 10 according to the first embodiment.

[0075] 6 is an enlarged cross-sectional view of the tapered portion 10BT of the optical fiber 10B and its vicinity in the catheter visualization device 2B according to the third embodiment. As shown in FIGS. 5 and 6, the tapered portion 10BT of the optical fiber 10B is located inside the connector 30B. That is, the optical fiber 10B has a compact size that can be accommodated within the connector 30B.

[0076] The connector 30B can be fixed to the base end 10Bb of the optical fiber 10B and the adjacent side surface by filling and curing an epoxy adhesive, for example. The adhesive to be used is preferably one that can be thermally cured at a low temperature of 70° C. or less, or one that can be UV-cured.

[0077] In this embodiment, the outer diameter of the small diameter portion 10BS of the optical fiber 10B is smaller than the inner diameter of the catheter 3, for example, 800 μm, and the diameter D2 of the core 11S at this portion is 750 μm. In the tapered portion 10BT of the optical fiber 10B, the diameter of the core 11BT at this portion is 750 μm, the same as the diameter D2 of the core 11S, at the most distal end side t, but gradually increases in diameter in a trumpet shape toward the proximal end side b. The diameter of the core 11BT at the most proximal end side b is 800 μm.

[0078] In the longitudinal direction of the optical fiber 10B (the left-right direction in FIG. 6), the length L1 of the tapered portion 10BT is, for example, 5 mm in this embodiment. In this embodiment, by shortening the length L1 of the tapered portion 10BT, the optical fiber 10B is made compact enough to fit inside the connector 30B.

[0079] Here, a method for designing the taper angle of the tapered portion 10BT will be described. Fig. 7 is an explanatory diagram for explaining the method for designing the taper angle of the tapered portion 10BT. Fig. 7 illustrates the boundary B between the core 11B and the cladding 12B in the tapered portion 10BT and the small diameter portion 10BS of the optical fiber 10B, and the trajectory OP of the most divergent laser light (referred to as the "laser divergence trajectory") of the laser light irradiated from the light emitting surface 22p of the light emitting portion 22.

[0080] The spread angle (°) of the laser spread locus OP is L ＥＸ , the taper angle (°) of the tapered portion 10BT is θ ｔ , the incident angle (°) of the laser light on the tapered portion 10BT is θ ｉｎ Then, the relationship of the following formula (1) is established. ｉｎ = 90 - (L ＥＸ +θ ｔ )...Formula (1)

[0081] The refractive index of the core 11B is L ｃｒ , the refractive index of the cladding 12B is L ｃｌ , the critical angle (minimum angle) θ of the incident angle at which the laser light is totally reflected at the boundary B between the core 11B and the cladding 12B. ｉ Then, the relationship of the following formula (2) is established. ｉ = asin(L ｃｌ / L ｃｒ ) ...Formula (2)

[0082] Therefore, the incident angle θ of the laser light ｉｎ is the critical angle θ ｉ By designing the tapered portion 10BT to satisfy the above, the total reflection of the laser light at the tapered portion 10BT can be achieved. If the total reflection of the laser light can be achieved, it is desirable because it is possible to suppress the radiation of light and the optical loss. In the case of a plastic fiber, for example, the refractive index L of the core 11B is ｃｒ is 1.49, and the refractive index of the cladding L ｃｌ When the angle is 1.05, the critical angle θ is ｉ is 45°. ｉ =asin(1.05 / 1.49)=45

[0083] Incident angle of laser light θｉｎ is the critical angle θ ｉ = 45° or more, for example, the spread angle L of the laser spread locus OP ＥＸ is 10°, the taper angle θ is as shown in the following equation, which is substituted into equation (1'), which is an inequality obtained by transforming equation (1). ｔ The angle should be set to 35° or more. ｉｎ ≧90-(L ＥＸ +θ ｔ )...Formula (1') 45≧90-(10+θ ｔ ) θ ｔ ≧35

[0084] The optical fiber 10B is inserted into the catheter 3, and the tip portion 10Bt is located at or near the tip portion 3t of the catheter 3. The catheter visualization device 2B causes light to be incident from the light source 20 at the proximal end surface 10Bb' of the proximal end 10Bb of the optical fiber 10B and to exit from the distal end surface 10Bt' of the distal end 10Bt of the optical fiber 10B. Therefore, by using the optical fiber 10B in this embodiment, it is possible to form a small-diameter portion 10BS with an extremely small diameter in the region on the distal end side t that is inserted into the catheter 3, and the diameter of the proximal end 10Bb is expanded by the tapered portion 10BT on the proximal end side b where the light is incident, thereby suppressing loss when light is incident from the light-emitting surface 22p of the light-emitting portion 22 of the light source 20.

[0085] The optical fiber 10B used in this embodiment can be manufactured, for example, as follows. An optical fiber that meets the required specifications, such as various dimensions and numerical aperture (NA), is prepared. One end of the prepared plastic optical fiber and its vicinity are heated, for example, to a temperature of approximately 120 to 180°C. This causes the end of the optical fiber to expand in a tapered shape, and once it has expanded to the desired diameter, heating is stopped and the optical fiber is allowed to cool naturally. In this way, an optical fiber 10B can be manufactured that is composed of a small diameter portion 10BS made of the prepared optical fiber and a tapered portion 10BT formed by heating the optical fiber.

[0086] The optical fiber 10B used in this embodiment can be easily manufactured by simply heating it as described above. In the catheter visualization device 2B according to this embodiment, even a small amount of tapered expansion of the proximal end of the optical fiber can provide an effect corresponding to the degree of expansion.

[0087] Other structures, materials, specifications, dimensions (including preferred conditions) of the optical fiber 10B in this embodiment are the same as those of the optical fiber 10 in the first embodiment.

[0088] The above-described embodiments merely show typical examples of the present invention, and the present invention is not limited to the above-described embodiments. For example, in the second embodiment, the optical fiber 10A is exemplified, in which the large diameter portion 10AL is made of a holey fiber and the small diameter portion 10AS is made of a double-clad fiber. However, either the large diameter portion or the small diameter portion may be made of a normal optical fiber with a single clad layer.

[0089] In addition, a double-clad fiber may be used in the large-diameter portion and a holey fiber in the small-diameter portion, or the same type of optical fiber may be used in both the large-diameter portion and the small-diameter portion. Of course, as mentioned above, the configuration of the second embodiment in which the large-diameter portion 10AL is made of a holey fiber and the small-diameter portion 10AS is made of a double-clad fiber is preferable in terms of the characteristics of the respective optical fibers.

[0090] In the third embodiment, the small-diameter portion 10BS is an ordinary optical fiber with a single-layer clad, but a double-clad fiber or holey fiber may be used for the small-diameter portion 10BS. In particular, when a holey fiber is used, the clad 12 derived from the holey fiber is also formed in the tapered portion 10BT, which reduces the loss of light when light is introduced into the base end 10Bb of the optical fiber 10B.

[0091] Furthermore, in the above three embodiments, examples are given in which the optical fiber is inserted into the catheter 3, but the optical fiber does not have to be inserted into the catheter as long as the tip of the optical fiber is located at or near the tip of the catheter during use. For example, the optical fiber may be fixed to the side of the catheter.

[0092] In addition, those skilled in the art may implement various modifications in accordance with conventionally known knowledge without departing from the gist of the present invention. As long as such modifications still comprise the configuration of the catheter visualization device and medical catheter set of the present invention, they are of course included in the scope of the present invention.

[0093] 1, 1A, 1B, 101: Medical catheter set, 2, 2A, 2B, 102: Catheter visualization device, 3, 103: Catheter, 4: Object, 10, 10A, 10B, 110: Optical fiber, 10b, 10Ab, 10Bb, 110b: Base end portion, 10b', 10Ab', 10Bb', 110b': Base end surface, 10t, 10At, 10Bt, 110t: Distal end portion, 10t', 10At', 10Bt', 110t': Distal end surface, 10S, 10AS, 10BS: Small diameter portion, 10L, 10AL, 10BL: Large diameter portion, 10T, 10AT, 10BT: Tapered portion, 11, 11A, 11B, 111: Core, 12, 12A, 12B, 112: Cladding, 12A-1: First cladding, 12A-2: Second cladding, 13: Hole, 20, 120: Light source, 21, 121: Light source main body, 22, 122: Light emitting portion, 22p, 122p: Light emitting surface, 23, 123: Locking protrusion, 30, 30B, 130: Connector, 33, 133: Locking hole

Claims

1. A catheter visualization device that enables the position of the tip of a catheter to be visualized, comprising an optical fiber having a core located radially toward the center and a cladding located on the outer periphery of the core, and having a base end and a tip end, and a light source that directs light into the optical fiber from the base end, wherein the optical fiber has a tapered portion between the base end and the tip end, in which the core tapers toward the tip end.

2. A catheter visualization device according to claim 1, wherein said core in at least said tapered section is quartz.

3. A catheter visualization device according to claim 1, wherein the optical fiber has the tapered portion, a large diameter portion closer to the base end than the tapered portion, and a small diameter portion closer to the tip end than the tapered portion, and the tapered portion and the large diameter portion or the tapered portion and the small diameter portion are connected by fusion.

4. A catheter visualization device according to claim 1, wherein the optical fiber has the tapered portion, a large diameter portion closer to the base end than the tapered portion, and a small diameter portion closer to the tip end than the tapered portion, and the numerical aperture (NA) of the large diameter portion of the optical fiber is 0.5 or greater.

5. The catheter visualization device of claim 4, wherein said large diameter section of said optical fiber comprises a holey fiber.

6. The catheter visualization device according to claim 1, wherein the optical fiber has at least the tapered portion and a small diameter portion located closer to the tip than the tapered portion, and the small diameter portion of the optical fiber is made of a double-clad fiber.

7. A catheter visualization device according to claim 1, wherein the diameter of the core at the position of the tapered portion closest to the proximal end is 500 μm or more.

8. A catheter visualization device according to claim 1, wherein the length of the tapered portion in the longitudinal direction of the optical fiber is 10 mm or more.

9. The catheter visualization device according to claim 1, further comprising a connector that surrounds and holds the proximal end of the optical fiber and its adjacent side surface so that the proximal end face of the proximal end of the optical fiber is positioned opposite the light emitting surface of the light source, and the tapered portion is located inside the connector.

10. The catheter visualization device of claim 1, wherein the light source is an LED that emits visible light.

11. A medical catheter set comprising the catheter visualization device according to claim 1 and a catheter.

12. The medical catheter set according to claim 11, wherein the optical fiber in the catheter visualization device is inserted into the catheter, and the tip of the optical fiber is located at or near the tip of the catheter.

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