Cannula

Abstract

This invention provides a cannula that is advantageous in suppressing breakage at the end of the shaft range of the intermediate shaft member. [Solution] The intermediate shaft member 36 has a coil 42 embedded in it and its shape can be adjusted by shaping, a base end member 38 is positioned on the base end side of the intermediate shaft member 36 and connected to the intermediate shaft member, and a tip end shaft member 40 is positioned on the tip side of the intermediate shaft member 36 and connected to the intermediate shaft member 36. The intermediate shaft member 36 is connected by welding to the base end member 38 and the tip end shaft member 40, or both, with the tip end shaft member 40 as the welding partner, and is provided with reinforcing members 66A and 66B positioned on the intermediate shaft member 36 at at least one end of the shaft range Ra that is near the welding partner.

Description

Technical Field

[0001] The present disclosure relates to a cannula.

Background Art

[0002] Patent Document 1 discloses a cannula to be inserted into the body.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In some cases, a coil is embedded in a shaft member constituting a cannula so that the shaft member is likely to develop a bend, and the shape can be adjusted by shaping. In this case, the cannula may include an intermediate shaft member in which a coil is embedded and can be shaped, a proximal end side member connected to the intermediate shaft member, and a distal end side shaft member connected to the intermediate shaft member. In this case, the intermediate shaft member is connected by welding with the distal end side shaft member or both of the proximal end side member and the distal end side shaft member as the welding partner.

[0005] The axial range from the boundary between the intermediate shaft member and the proximal end side member to the boundary between the distal end side shaft member and the intermediate shaft member is referred to as the shaft range. At this time, when the inventor of the present application studied, it was found that when a coil is embedded in the intermediate shaft member, the intermediate shaft member may break at the end of the shaft range near the welding partner.

[0006] Therefore, one object of the present disclosure is to provide a cannula that is advantageous for suppressing breakage at the end of the shaft range of the intermediate shaft member.

Means for Solving the Problems

[0007] The cannula of this disclosure comprises an intermediate shaft member in which a coil is embedded and whose shape can be adjusted by shaping; a base-end member disposed on the base end side of the intermediate shaft member and connected to the intermediate shaft member; and a tip-end shaft member disposed on the tip end side of the intermediate shaft member and connected to the intermediate shaft member, wherein the intermediate shaft member is connected by welding to the base-end member and the tip-end shaft member, or both, with the tip-end shaft member as the welding partner, and the shaft range is defined as the axial range from the base-end boundary between the outer surface of the base-end member and the outer surface of the intermediate shaft member to the tip-end boundary between the outer surface of the tip-end shaft member and the outer surface of the intermediate shaft member, and the cannula comprises a reinforcing member disposed on the intermediate shaft member at at least one end of the shaft range that is near the welding partner. [Effects of the Invention]

[0008] According to this disclosure, a cannula can be provided that is advantageous in suppressing breakage at the end of the shaft range of the intermediate shaft member. [Brief explanation of the drawing]

[0009] [Figure 1] This is a diagram illustrating the usage scenarios of a cannula. [Figure 2] This is a side view showing the cannula of the embodiment. [Figure 3] This is a schematic cross-sectional view showing the main part of the cannula of the embodiment. [Figure 4] This is a schematic diagram illustrating the tip welding process. [Figure 5] This is a schematic diagram illustrating the base end welding process. [Figure 6A] This is the first explanatory diagram showing the procedure for measuring the reference angle. [Figure 6B] This is the second explanatory diagram showing the procedure for measuring the reference angle. [Figure 6C] This is the third explanatory diagram showing the procedure for measuring the reference angle. [Modes for carrying out the invention]

[0010] Embodiments for carrying out the cannula of this disclosure are described below. The same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted. For the sake of clarity, components are omitted, enlarged, or reduced in each drawing. The drawings should be viewed in accordance with the orientation of the reference numerals.

[0011] Refer to Figure 1. First, we will explain the usage scenarios of the cannula 10, along with the background that led to the conception of this form of cannula 10. Here, we will explain an example in which the cannula 10 is used in ERCP (Endoscopic Retrograde Chaolangiopancreatography). ERCP is an examination in which a contrast agent is injected into either the bile duct or pancreatic duct, which is the organ to be treated, and the condition of the organ is examined by X-ray imaging using the contrast agent. This is just one example of the use of the cannula 10, and it is not limited to this.

[0012] The cannula 10 is used in combination with the endoscope 12. The endoscope 12 comprises an endoscope body 16 in which a channel 14 is formed, and an upright base 18 that is rotatably attached to the endoscope body 16. The shaft 30 of the cannula 10 is fed out from the channel 14 through the upright base 18 to the outside. The direction in which the shaft 30 is fed out from the endoscope 12 to the outside is adjusted by changing the rotation angle of the upright base 18 relative to the endoscope body 16.

[0013] The shaft 30 of the cannula 10 is sent out from the channel 14 of the endoscope 12, which is positioned inside the first organ 20, and is used for cannulation by insertion into the entrance 22a of the second organ 22, which opens to the inner surface of the first organ 20. Here, we show an example where the first organ 20 is the duodenum and the second organ 22 is the biliary tract. Thus, the first organ 20 and the second organ 22 are each digestive organs of a living organism, but the specific examples are not particularly limited. When cannulation, it is desirable to be able to adjust the shape of a part of the shaft 30 by shaping, as this allows for adjustment of the position and orientation of the tip of the shaft 30 relative to the endoscope 12, thereby improving the ease of insertion into the entrance 22a of the second organ 22.

[0014] Refer to Figure 3. To meet such requirements, the cannula 10 in this embodiment is equipped with an intermediate shaft member 36 whose shape can be adjusted by shaping. In order to allow the shape to be adjusted by shaping, a coil 42 may be embedded in the intermediate shaft member 36 so that it is easy to create a bending habit. In addition to the intermediate shaft member 36 in which the coil 42 is embedded, the cannula 10 in this embodiment is equipped with a base-end member 38 connected to the intermediate shaft member 36 and a tip-end shaft member 40 connected to the intermediate shaft member 36. In this embodiment, the base-end member 38 becomes a shaft member that constitutes the shaft 30. The intermediate shaft member 36 is connected by welding to the tip-end shaft member 40 of the base-end member 38 and the tip-end shaft member 40, or both, as welding partners. In this embodiment, both the base-end member 38 and the tip-end shaft member 40 are welding partners. The boundary between the outer surface of the intermediate shaft member 36 and the outer surface of the base-end member 38 is called the base-end boundary 50. The boundary between the outer surface of the intermediate shaft member 36 and the outer surface of the tip-side shaft member 40 is called the tip-side boundary 52. ​​The axial range from the base-side boundary 50 to the tip-side boundary 52 is called the shaft range Ra.

[0015] The conventional problems of this cannula 10 will be described. When welding the intermediate shaft member 36 to an adjacent welding partner, the vicinity of the boundary portions 50 and 52 with the welding partner is heated, and a part of the intermediate shaft member 36 softens. Due to this, at the end of the shaft range Ra of the intermediate shaft member 36, a part of the coil 42 can flow so as to move radially outward by the restoring force acting on the coil 42.

[0016] As a result, at the end of the shaft range Ra, the wall thickness of the outer wall portion 60 (details will be described later) of the intermediate shaft member 36 that is radially outside the coil 42 may become thinner. When the outer wall portion 60 of the intermediate shaft member 36 becomes thinner in this way, when the intermediate shaft member 36 is bent and deformed for shaping, it becomes easy to crack starting from the thinned portion, and it becomes easy to break at the end of the shaft range Ra. That is, at the end of the shaft range Ra, the intermediate shaft member 36 may break due to the thinning of the outer wall portion 60 of the intermediate shaft member 36.

[0017] As a countermeasure, the cannula 10 of this embodiment includes reinforcing members 66A and 66B disposed at the ends of the shaft range Ra in the intermediate shaft member 36. Thereby, the bending deformation of the intermediate shaft member 36 at the locations where the reinforcing members 66A and 66B are disposed can be restrained by the reinforcing members 66A and 66B. Therefore, even when the outer wall portion 60 of the intermediate shaft member 36 becomes thinner at the end of the shaft range Ra, by suppressing the bending deformation of the intermediate shaft member 36 at the locations where the reinforcing members 66A and 66B are disposed, it becomes easier to suppress cracking starting from the thinned portion of the intermediate shaft member 36. As a result, it is advantageous for suppressing breakage due to the thinning of the outer wall portion 60 at the end of the shaft range Ra of the intermediate shaft member 36. Hereinafter, the cannula 10 of this embodiment made under such a concept will be described.

[0018] Refer to FIG. 2. The cannula 10 includes a shaft 30 to be inserted into the body, and a handle 32 connected to the proximal end of the shaft 30 and grasped by an operator. The direction along the center line of the shaft 30 is simply referred to as the "axial direction", and the radial direction and circumferential direction with respect to its center line are simply referred to as the "radial direction" and "circumferential direction". One axial side (the left side of the paper in FIG. 2) of the shaft 30 is the distal end side disposed in the body, and the other axial side (the right side of the paper in FIG. 2) is the proximal end side disposed outside the body.

[0019] Refer to FIG. 3. A lumen 34 is formed in the shaft 30. The lumen 34 is for passing a contrast agent. The contrast agent is passed into the lumen 34 from a port 32a (refer to FIG. 2) provided on the handle 32 and injected into the organ to be treated from the distal end of the shaft 30. A device such as a guide wire can also be passed through the lumen 34.

[0020] The shaft 30 is composed of a plurality of shaft members 36, 40 arranged axially. The plurality of shaft members 36, 40 include an intermediate shaft member 36 and a distal shaft member 40 disposed on the distal side with respect to the intermediate shaft member 36 and connected to the intermediate shaft member 36.

[0021] The cannula 10 of this embodiment includes a proximal end side member 38 disposed on the proximal end side with respect to the intermediate shaft member 36 and connected to the intermediate shaft member 36. The proximal end side member 38 of this embodiment is a shaft member constituting a part of the shaft 30 and constitutes a portion on the proximal end side of the intermediate shaft member 36 of the shaft 30. The proximal end side member 38 serving as a shaft member may be constituted by a single member or may be constituted by a plurality of members arranged axially and connected to each other. The distal end portion of the proximal end side member 38 serving as a shaft member of this embodiment overlaps radially outside with respect to the proximal end portion of the intermediate shaft member 36.

[0022] The tip-side shaft member 40 is a tip member that constitutes the tip of the shaft 30. The outer circumference of the tip-side shaft member 40 is provided with an outer tapered portion 40a that decreases in diameter towards the tip. The tip-side shaft member 40 is made of various resin materials used in the cannula 10, such as polyolefin resin, which will be described later. The hardness of the tip-side shaft member 40 may be less than the hardness of the intermediate shaft member 36.

[0023] The intermediate shaft member 36 is connected by welding to the base end member 38 and the tip end shaft member 40, or both, using the tip end shaft member 40 as the welding partner. In this embodiment, both are used as welding partners. Alternatively, only the tip end shaft member 40 may be used as the welding partner. In this case, the intermediate shaft member 36 may be connected to the base end member 38, which will become the shaft member, by adhesive or the like. Furthermore, if only the tip end shaft member 40 is used as the welding partner, the base end member 38 may be the handle 32 as described later.

[0024] The intermediate shaft member 36 constitutes at least a portion of the shaft 30 that is extended outward from the channel 14 of the endoscope 12. The base end of the intermediate shaft member 36 may be provided with an inner circumferential tapered portion 36a that tapers toward the tip. This makes it easier to pass a device such as a guide wire smoothly toward the tip without snagging.

[0025] The shape of the intermediate shaft member 36 can be adjusted by shaping. This shaping can be achieved, for example, by one of the following methods: (1) is a method in which the intermediate shaft member 36 is shaped by the operator manually bending it outside the body prior to the insertion of the shaft 30 into the body; (2) is a method in which the intermediate shaft member 36 is shaped by bending it as it is fed out from the channel 14 of the endoscope 12 using the standing platform 18.

[0026] In order to allow the shape of the intermediate shaft member 36 to be adjusted by shaping, it is necessary to increase the ease with which the intermediate shaft member 36 can be bent. For this purpose, a coil 42 is embedded in the intermediate shaft member 36 of this embodiment. Here, "easy to bend" means that it is easy to maintain a state bent at a large curvature by shaping. The coil 42 has a shape in which strands of wire are wound in a spiral. The material of the strands of the coil 42 may be a metallic material such as stainless steel, or a resin material such as polyetheretherketone (PEEK). The coil 42 is provided so as to surround the lumen 34 formed in the intermediate shaft member 36.

[0027] To improve the ease of inducing a bend in the coil 42, the pitch of the coil 42 can be made denser, or the wire diameter of the coil 42 can be increased. In addition, to improve the ease of shaping the intermediate shaft member 36, a material that easily takes on a bend can be used for the intermediate shaft member 36, or the wall thickness (described later) of the intermediate shaft member 36 can be increased. Examples of materials that easily take on a bend include polyolefin resins and fluororesins (e.g., polytetrafluoroethylene (PTFE)). Polyolefin resins include, for example, polypropylene resins and polyethylene resins. As for polyethylene resins, for example, high-density polyethylene (HDPE), which has excellent cost, hardness, and pushability, may be used. If ease of inducing a bend is not considered, the intermediate shaft member 36 may be made of various resin materials used in cannulas 10, such as polyamide, polyether block amide, polyurethane, in addition to the aforementioned polyolefin resins and fluororesins. The base end member 38, which is the shaft member, may also be made of these various resin materials.

[0028] The intermediate shaft member 36 comprises at least one resin layer 44, 46. The intermediate shaft member 36 in this embodiment comprises an inner resin layer 44 that forms the lumen 34 and an outer resin layer 46 that covers the inner resin layer 44. The coil 42 in this embodiment is embedded in the outer resin layer 46 while wound around the inner resin layer 44. This can be achieved, for example, by extruding the outer resin layer 46 onto the coil 42 wound around the inner resin layer 44. The outer resin layer 46 into which the coil 42 is embedded may be made of, for example, a polyolefin resin. In addition, the inner resin layer 44 may also be made of a polyolefin resin. Each resin layer 44, 46 in this embodiment is made of a transparent resin material. This makes it possible to determine the presence or absence of contrast agent, guide wire, etc. in the lumen 34 by observation using a camera provided on the endoscope 12.

[0029] Refer to Figures 4 and 5. The manufacturing process of the cannula 10 includes a tip welding process (see Figure 4) in which the tip shaft member 40 and the intermediate shaft member 36 are welded together, and a base welding process (see Figure 5) in which the intermediate shaft member 36 and the base member 38 are welded together.

[0030] Refer to Figure 4. The tip welding process is performed, for example, by welding the ends of the tubular material shaft member 56, which will be the material for the tip shaft member 40, and the intermediate shaft member 36 together using a heat shrink tube 54. In this embodiment, the base end face of the material shaft member 56 and the tip end face of the intermediate shaft member 36 are butted together and welded. In this case, the aforementioned tip boundary portion 52 between the tip shaft member 40 and the intermediate shaft member 36 is provided at the butt joint between the end faces of the intermediate shaft member 36 and the tip shaft member 40. A mandrel 57 for securing the lumen is passed through the inside of each shaft member 36, 56. The shape of the material shaft member 56 is adjusted to match the outer shape of the tip shaft member 40.

[0031] The heat-shrinkable tube 54 is a tube that shrinks in diameter when heated. The heat-shrinkable tube 54 is placed over the base end of the material shaft member 56 and the tip end of the intermediate shaft member 36 in the axial direction. With the heat-shrinkable tube 54 covering the shaft, a heating range Rb including at least a portion of the base end of the material shaft member 56 and the tip end of the intermediate shaft member 36 is heated using a heating machine such as a dryer. This heating range Rb includes, for example, an axial range Rc of 2 mm or more toward the base end from the point that becomes the tip-side boundary 52 between the tip-side shaft member 40 and the intermediate shaft member 36. As a result, the base end of the material shaft member 56 and the tip end of the intermediate shaft member 36 are welded together. At this time, the degree of welding of each shaft member 36, 56 can be increased because the shaft members 36, 56 are welded together with the compression of the material shaft member 56 and the intermediate shaft member 36 due to the shrinkage of the heat-shrinkable tube 54. In this embodiment, the heat-shrinkable tube 54 is removed after the tip-side welding process.

[0032] Refer to Figure 5. The base end welding process is also performed, for example, by using a mandrel (not shown) and a heat shrink tube 58 to weld the ends of the intermediate shaft member 36 and the base end member 38, which will become the shaft member, together by heating them. In this embodiment, the process is performed with the tip of the base end member 38 overlapping the radially outer base end of the intermediate shaft member 36. In this case, the base end boundary portion 50 between the base end member 38 and the intermediate shaft member 36 is provided at a certain location of the tip of the base end member 38.

[0033] The heat-shrinkable tube 54 is applied so as to span the base end of the intermediate shaft member 36 and the tip of the base-end side member 38 in the axial direction. With the heat-shrinkable tube 54 applied, the heating area Rd, which includes at least a portion of the base end of the intermediate shaft member 36 and the tip of the base-end side member 38, is heated using a heating device such as a dryer.

[0034] Returning to Figure 3, the dashed line L42 passing through the coil 42 in Figure 3 indicates the position of the circumscribed circle that circumscribes the coil 42 with respect to the center line C34 of the lumen 34 formed in the intermediate shaft member 36. The aforementioned outer wall portion 60 is an annular portion from this circumscribed circle L42 to the outer circumferential surface of the intermediate shaft member 36, and refers to a portion that is continuously provided in a certain axial range of the coil 42. The thickness of the outer wall portion 60 refers to the distance from this circumscribed circle L42 to the outer circumferential surface of the intermediate shaft member 36 in a direction perpendicular to the center line C34 of the lumen 34. When reinforcing members 66A and 66B are arranged on the outer circumferential surface of the intermediate shaft member 36, the portion that contacts the inner circumferential surface of the reinforcing members 66A and 66B is considered as part of the outer circumferential surface of the intermediate shaft member 36, and the thickness of the outer wall portion 60 is considered accordingly.

[0035] The intermediate shaft member 36 comprises a thick-walled region 62 provided in the middle of the shaft range Ra, and at least one thin-walled region 64A, 64B provided at the ends Ra1, Ra2 of the shaft range Ra, where the thickness of the outer wall portion 60 is thinner than that of the thick-walled region 62. Each of the thick-walled region 62 and the thin-walled regions 64A, 64B constitutes a part of the axial range of the intermediate shaft member 36 in the shaft range Ra. The intermediate shaft member 36 in this embodiment comprises a plurality of thin-walled regions 64A, 64B. The plurality of thin-walled regions 64A, 64B include a tip-side thin-walled region 64A provided at the tip portion Ra1 of the shaft range Ra, and a base-side thin-walled region 64B provided at its base portion Ra2.

[0036] The thickness of the outer portion 60 of the thick-walled region 62 does not vary much with respect to the axial position of the thick-walled region 62, and remains roughly the same in the axial direction. Here, "equivalent" is a concept that includes both cases where the two objects being referred to are identical and cases where they are nearly identical. In contrast, the thickness of the outer portion 60 of the thin-walled regions 64A and 64B may vary with respect to the axial position of the thin-walled regions 64A and 64B. The thickness of the outer portion 60 of these thin-walled regions 64A and 64B may gradually decrease from the thickness of the thick-walled region 62 as it moves away from the thick-walled region 62 in the axial direction, up to a certain size. Here, we show an example where the thickness of the outer portion 60 of the thin-walled regions 64A and 64B becomes roughly the same in the axial direction once it reaches a certain size.

[0037] The thin-walled regions 64A and 64B are caused by the softening of the intermediate shaft member 36 during welding. For example, as shown in Figure 4, the tip-side thin-walled region 64A is caused by the softening of the intermediate shaft member 36 at the tip of the shaft range Ra, where it overlaps with the heating range Rb, resulting in a thinning of the outer wall portion 60. Similarly, as shown in Figure 5, the base-side thin-walled region 64B is caused by the softening of the intermediate shaft member 36 at the base end of the shaft range Ra, where it overlaps with the heating range Rd, resulting in a thinning of the outer wall portion 60.

[0038] As described above, the cannula 10 is provided with at least one reinforcing member 66A, 66B positioned on the intermediate shaft member 36 at at least one end Ra1, Ra2 of the shaft range Ra that is near the welding partner as described above. Here, "at least one end" refers only to the tip portion Ra1 of the shaft range Ra that is near the tip shaft member 40 when only the tip shaft member 40 is connected to the intermediate shaft member 36 as a welding partner. In contrast, when both the tip shaft member 40 and the base end member 38 are connected to the intermediate shaft member 36 as welding partners, it refers to at least one of the tip portion Ra1 of the shaft range Ra that is near the tip shaft member 40 and the base end portion Ra2 of the shaft range Ra that is near the base end member 38.

[0039] The cannula 10 in this embodiment includes a plurality of reinforcing members 66A and 66B. The plurality of reinforcing members 66A and 66B include a tip-side reinforcing member 66A positioned at the tip portion Ra1 of the shaft range Ra on the intermediate shaft member 36, and a base-side reinforcing member 66B positioned at its base portion Ra2. It can also be said that the tip-side reinforcing member 66A is positioned in the intermediate shaft member 36 at a location that radially overlaps with the tip portion Ra1 of the shaft range Ra, and the base-side reinforcing member 66B is positioned at a location that radially overlaps with the base portion Ra2 of the shaft range Ra. The reinforcing members 66A and 66B reinforce the bending rigidity of the intermediate shaft member 36 at the locations where the reinforcing members 66A and 66B are positioned. As long as this condition is met, the specific examples of the reinforcing members 66A and 66B are not particularly limited. The reinforcing members 66A and 66B in this embodiment are composed of ring members, but are not limited to this, and may be composed of coils or the like. In this embodiment, the reinforcing members 66A and 66B are provided so as to surround the center line C34 of the lumen 34. The inner diameter of the reinforcing members 66A and 66B may preferably be the same as the inner diameter of the lumen 34. The inner diameter of the reinforcing members 66A and 66B may be larger than the inner diameter of the lumen 34. The material of the reinforcing members 66A and 66B may be one that has higher hardness than the material of the resin layer 46 of the intermediate shaft member 36 in which the reinforcing members 66A and 66B are embedded. In order to satisfy this condition, in addition to metal materials such as stainless steel, resin materials such as PEEK may be used.

[0040] The reinforcing members 66A and 66B are fixed to the intermediate shaft member 36. In this embodiment, the reinforcing members 66A and 66B are fixed to the intermediate shaft member 36 by press-fitting them into the inner circumferential surface of the intermediate shaft member 36 that forms the lumen 34. In this embodiment, the inner circumferential surfaces of the reinforcing members 66A and 66B are flush with the inner circumferential surface of the intermediate shaft member 36 that is axially adjacent to the reinforcing members 66A and 66B, and the lumen 34 is formed inside them. In addition, the reinforcing members 66A and 66B may be embedded in the resin layer constituting the intermediate shaft member 36 or placed on the outer periphery of the intermediate shaft member 36. In any case, the specific means for fixing the reinforcing members 66A and 66B to the intermediate shaft member 36 are not particularly limited. In any case, the reinforcing members 66A and 66B are fixed to the intermediate shaft member 36 prior to the various welding processes described above.

[0041] Bending of the intermediate shaft member 36 due to thinning of the outer wall portion 60 is more likely to occur in areas including the thin-walled regions 64A and 64B of the outer wall portion 60. For this reason, it is preferable that the reinforcing members 66A and 66B be placed in at least a portion of the axial range of such thin-walled regions 64A and 64B. This allows the reinforcing members 66A and 66B to suppress bending deformation in the thin-walled regions 64A and 64B compared to the case without them, thereby suppressing cracking originating from the thin-walled regions 64A and 64B. In order to suppress cracking originating from the thin-walled regions 64A and 64B, the reinforcing members 66A and 66B do not need to be placed over the entire axial range of the thin-walled regions 64A and 64B. In arranging them in the positional relationship described above, the tip-side reinforcing member 66A only needs to be placed in at least a portion of the axial range of the tip-side thin-walled region 64A. Furthermore, the base-side reinforcing member 66B only needs to be positioned in at least a portion of the axial range where the base-side thin-walled region 64B exists. Even when the reinforcing members 66A and 66B are positioned on the outer circumference of the intermediate shaft member 36, the reinforcing members 66A and 66B may still be positioned at the ends Ra1 and Ra2 of the intermediate shaft member 36 where the thin-walled regions 64A and 64B exist.

[0042] The tip-side reinforcing member 66A is preferably provided at least in part at a position 0.2 to 5.0 mm from the tip-side boundary portion 52 toward the base end. This is advantageous in suppressing bending deformation at the thinned portion even when the outer wall portion 60 of the intermediate shaft member 36 is thinned at the tip portion Ra1 of the shaft range Ra. The axial length L66A of the tip-side reinforcing member 66A is preferably in the range of 0.5 to 5.0 mm. This is advantageous in reducing the axial length of the portion of the intermediate shaft member 36 where bending deformation is constrained by the tip-side reinforcing member 66A, thereby reducing the influence on the ease with which the intermediate shaft member 36 develops a bending habit. These conditions are set based on findings obtained by the inventors of the present invention through experimental and analytical studies.

[0043] It is preferable that the tip-side reinforcing member 66A is provided at an axial distance from the tip-side shaft member 40. This makes it easier to secure the wall thickness of the intermediate shaft member 36 at its tip compared to the case where the tip-side reinforcing member 66A is positioned in the axial range including the tip of the intermediate shaft member 36. Consequently, it becomes easier to secure the wall thickness of the welded portion of the intermediate shaft member 36 to the tip-side shaft member 40, which is advantageous in securing the strength of the welded portion.

[0044] In this embodiment, the cannula 10 optionally includes a covering tube 68 that is placed over the tip-side shaft member 40 and the intermediate shaft member 36 so as to straddle the tip-side boundary portion 52 in the axial direction. The covering tube 68 is provided to prevent the tip of the coil 42 from popping out due to the softening of the intermediate shaft member 36 during the tip-side welding process. Alternatively, the covering tube 68 may be omitted, leaving the heat-shrinkable tube 54 used in the tip-side welding process in place.

[0045] The base-side reinforcing member 66B is preferably provided in at least a portion of the base-side boundary portion 50 at a position 0 to 1.0 mm toward the tip. This is advantageous in suppressing bending deformation at the thinned portion even when the outer wall portion 60 of the intermediate shaft member 36 is thinned at the base end portion Ra2 of the shaft range Ra. Furthermore, the axial length L66B of the base-side reinforcing member 66B is preferably in the range of 0.5 to 10 mm. This is advantageous in reducing the axial length of the portion of the intermediate shaft member 36 where bending deformation is constrained by the reinforcing member 66B, thereby reducing the influence on the ease with which the intermediate shaft member 36 develops a bending habit. These conditions are set based on findings obtained by the inventors of the present invention through experimental and analytical studies.

[0046] The base end reinforcing member 66B may be positioned in an axial range that includes a position P1 that radially overlaps with the base end boundary portion 50. The intermediate shaft member 36 has a coil 42 embedded in it so as to straddle this position P1 in the axial direction, and there is a risk that the intermediate shaft member 36 may break at this position P1 due to the thinning of the outer wall portion 60. By embedding the coil 42 in the intermediate shaft member 36 in an axial range that includes such a position P1, it is advantageous to suppress the breakage of the intermediate shaft member 36 caused by the thinning at that position P1.

[0047] The thickness t1 of the outer wall portion 60 of the thin-walled regions 64A and 64B, and the thickness t2 of the outer wall portion 60 of the thick-walled region 62 are examined. The thickness t1 is determined individually for each of the thin-walled regions 64A at the tip and 64B at the base. The thickness t1 may be the thinnest thickness of the outer wall portion 60 at the ends Ra1 and Ra2 of the shaft range Ra where the corresponding thin-walled regions 64A and 64B are located. The thickness t2 may be the average value of the measured thickness at multiple locations in the central part of the shaft range Ra where the thickness of the outer wall portion 60 of the thick-walled region 62 is equal in the axial direction. These multiple locations may be at least three locations spaced apart by the pitch of the coil 42. For the sake of explanation, the thickness of the outer wall portion 60 at one location in the central part of the shaft range Ra is shown here as the thickness t2 of the thick-walled region 62.

[0048] In this case, the ratio (=t1 / t2) of the wall thickness t1 of the thin-walled regions 64A and 64B to the wall thickness t2 of the thick-walled region 62 is, for example, 1:3 (=1 / 3) or less. This condition expresses, using a guideline ratio value, that the wall thickness t1 of the outer wall portion 60 in the thin-walled regions 64A and 64B is to some extent thinner than the wall thickness t2 of the outer wall portion 60 in the thick-walled region 62. This condition only needs to be satisfied between at least one of the thin-walled region 64A at the tip and the thin-walled region 64B at the base and the thick-walled region 62. In this embodiment, it is satisfied between each of the thin-walled regions 64A and 64B and the thick-walled region 62. According to this embodiment, even if the thickness of the outer wall portion 60 is reduced in the thin-walled regions 64A and 64B of the shaft range Ra, the reinforcing members 66A and 66B arranged in the thin-walled regions 64A and 64B are advantageous in suppressing the breakage of the intermediate shaft member 36 caused by the thinning.

[0049] Let the thickness of the intermediate shaft member 36 be t3. Here, the thickness of the intermediate shaft member 36 refers to the distance perpendicular to the center line C34 of the lumen 34 from the inner circumferential surface to the outer circumferential surface of the intermediate shaft member 36, where the lumen 34 is located on the inside, at a point in the shaft range Ra where it does not overlap radially with the reinforcing members 66A and 66B. At a point in the shaft range Ra where it does not overlap radially with the reinforcing members 66A and 66B, the thickness of the intermediate shaft member 36 remains almost constant in the axial direction. Similar to the thickness t2, the average value of the measured thickness at multiple points in the central part of the shaft range Ra where the thickness of the intermediate shaft member 36 is constant in the axial direction may be used as the thickness t3.

[0050] In this case, the ratio (=t1 / t3) of the thickness t1 of the outer wall portion 60 of the thin-walled regions 64A and 64B to the thickness t3 of the intermediate shaft member 36 may be, for example, 1:5 (=1 / 5) or less. This condition expresses, using a guideline ratio value, that the thickness t1 of the outer wall portion 60 of the thin-walled regions 64A and 64B is somewhat thinner than the thickness t3 of the intermediate shaft member 36. This condition only needs to be satisfied between at least one of the thin-walled region 64A at the tip and the thin-walled region 64B at the base and the thickness t3 of the intermediate shaft member 36. According to this embodiment, even if the thickness of the outer wall portion 60 in the thin-walled regions 64A and 64B is reduced in this way, the reinforcing members 66A and 66B placed in the thin-walled regions 64A and 64B are advantageous in suppressing the breakage of the intermediate shaft member 36 caused by the reduction in wall thickness.

[0051] The effects of the cannula 10 described above are explained below. Polyolefin resins are known to be easy to bend, but they also have a low melting point. Therefore, when polyolefin resin is used for the intermediate shaft member 36, the coil 42 tends to flow easily due to the softening effect of the intermediate shaft member 36 during welding, and the intermediate shaft member 36 is prone to breaking due to the thinning of the outer wall portion 60. In other words, when polyolefin resin is used for the intermediate shaft member 36, it is easy to bend, but as a trade-off, it is prone to breaking. Furthermore, polyolefin resins (especially high-density polyethylene) are easier to bend than polyether block amides used in ordinary catheters, but they tend to have lower toughness, which also contributes to the tendency to break. In this respect, according to this embodiment, since reinforcing members 66A and 66B are used as described above, it is advantageous in suppressing the breaking of the intermediate shaft member 36. Therefore, it is advantageous in improving the ease with which the intermediate shaft member 36 can be bent, while simultaneously solving the problem of the intermediate shaft member 36 breaking, which arises as a trade-off. In particular, it is advantageous in that it can achieve both ease of bending and resistance to breaking of the intermediate shaft member 36, which cannot be achieved with polyether block amide used in ordinary catheters.

[0052] The reinforcing members 66A and 66B are positioned so as to overlap radially with at least a portion of the thin-walled regions 64A and 64B of the intermediate shaft member 36. Therefore, by suppressing the bending deformation in the thin-walled regions 64A and 64B with the reinforcing members 66A and 66B, it becomes easier to suppress cracking originating from the thin-walled regions 64A and 64B, which is advantageous in suppressing breakage caused by the thin-walled regions 64A and 64B.

[0053] The reinforcing members 66A and 66B include the tip-side reinforcing member 66A. Therefore, even if the outer wall portion 60 is thinned at the tip portion Ra1 of the shaft range Ra, the tip-side reinforcing member 66A is advantageous in suppressing breakage at that tip portion Ra1.

[0054] The reinforcing members 66A and 66B include the base end reinforcing member 66B. Therefore, even if the outer wall portion 60 is thinned at the base end Ra2 of the shaft range Ra, the base end reinforcing member 66B is advantageous in suppressing breakage at that base end Ra2.

[0055] Next, other features of the cannula 10 will be described. The tip-side reinforcing member 66A may be made of a material that is opaque to radiation such as X-rays (hereinafter referred to as the opaque material). This opaque material may be a metallic material such as barium, gold, platinum, or tungsten, or a resin material that is opaque to radiation, or a mixture of these metallic materials and a resin material such as PEEK. The tip-side reinforcing member 66A made of the opaque material is displayed separately from the part that transmits radiation in the imaging image using radiation, and functions as a marker to identify the position of the tip of the cannula 10. By making the tip-side reinforcing member 66A out of an opaque material in this way, the intermediate shaft member 36 can be reinforced while the tip-side reinforcing member 66A can be used as a marker. The proximal end reinforcing member 66B does not have to be made of a material that is opaque to radiation like the tip-side reinforcing member 66A, or it may be made of such a material.

[0056] In this embodiment, the tip-side shaft member 40 is not provided with a marker portion made of an impermeable material. In this embodiment, the function of the marker portion that would be provided on the tip-side shaft member 40 is taken over by the tip-side reinforcing member 66A. As a result, when providing a marker on the cannula 10 to identify the position of the tip of the cannula 10, it is not necessary to provide a marker portion on the tip-side shaft member 40, which is advantageous in reducing the axial length of the tip-side shaft member 40. Furthermore, by reducing the axial length of the tip-side shaft member 40 without changing the overall axial length of the cannula 10, it becomes possible to increase the axial length of the intermediate shaft member 36, which has excellent kink resistance due to the coil 42.

[0057] The ease with which the intermediate shaft member 36 is prone to bending can be quantitatively evaluated by a reference angle θs measured by a bending test described below. In this bending test, first, a straight shaft 30 is prepared as shown in Figure 6A. Then, as shown in Figure 6B, a portion of the intermediate shaft member 36 of the shaft 30 is wrapped around a cylindrical body 70 with a diameter of 9.0 mm for one turn, and a weight 72 with a weight of 5.0 N is suspended from the tip 30a of the shaft 30. Here, an example is shown in which a weight 72 comprising a measuring jig 74 and a weight body 76 is suspended. The measuring jig 74 comprises a jig body 74a that clamps the shaft 30 and a first hook 74b provided on the jig body 74a. The weight body 76 comprises a second hook 76a that is hooked onto the first hook 74b and a weight portion 76b that is suspended and supported by the second hook 76a. The configuration of this weight 72 is just an example, and its specific examples are not particularly limited.

[0058] The shaft 30 comprises a tip-side straight portion 30c located on the tip side of the shaft 30 beyond the winding portion 30b of the shaft 30 around the cylindrical body 70, and a base-side straight portion 30d located on the base side of the shaft 30 beyond the winding portion 30b. When the shaft 30 is wound around the cylindrical body 70, the tip-side straight portion 30c and the base-side straight portion 30d of the shaft 30 are arranged so that they are aligned in a straight line when viewed from the axial direction of the cylindrical body 70 (the direction perpendicular to the plane of the paper in Figure 6B).

[0059] The weight 72 is suspended from the shaft 30 in this manner and held for at least 30 seconds. After this, as shown in Figure 6C, when the weight 72 is removed from the shaft 30, the portion 30b of the shaft 30 wrapped around the cylindrical body 70 returns to its bent state. Since the portion 30b of the shaft 30 gradually returns to its original state after the weight 72 is removed, wait until it reaches a stationary state where the restoration has completely stopped. The amount of angular change at the portion 30b of the shaft 30 when it reaches this stationary state, relative to its initial state (the state in Figure 6A), is defined as the reference angle θs.

[0060] The positional relationship of the stationary shaft 30 as viewed from the axial direction of the cylindrical body 70 (the direction perpendicular to the plane of the paper in Figure 6B) is examined. The straight line along the centerline of the straight portion 30c at the tip of the shaft 30 is defined as the first reference line Lb1, and the straight line along the centerline of the straight portion 30d at the base is defined as the second reference line Lb2. The intersection of the first reference line Lb1 and the second reference line Lb2 is defined as the origin Po. In this case, the reference angle θs is defined as the angle made by the first reference line Lb1 with respect to the second reference line Lb2 around the origin Po. This reference angle θs is defined with the starting line being the portion of the second reference line Lb2 extending from the origin Po toward the tip 30a of the shaft 30 in its initial state (shown as a dashed line in Figure 6C), and the winding direction relative to the cylindrical body 70 (counterclockwise in this case) is defined as the positive direction of the angle. This reference angle θs may be measured using, for example, a protractor or image analysis. At this time, the reference angle θs is measured with at least a portion of the shaft 30 (for example, the straight portion 30d at the base end) placed on a flat surface such as a table. The work from suspending the weight 72 from the shaft 30 to measuring the reference angle θs is performed at room temperature (20°C to 30°C).

[0061] The larger the reference angle θs, the easier it is to maintain a bent state with a large curvature, thereby improving the ease of inserting the shaft 30, which is sent out from the endoscope 12, into the second organ 22. From this perspective, the reference angle θs may be set to 90° or more. This is defined using a numerical value that serves as a guideline for when the intermediate shaft member 36 is prone to bending. When polyether block amide, a common material for the intermediate shaft member 36, is used, this reference angle θs is approximately 25°. Although there is no particular upper limit to the reference angle θs, it is 360° in relation to the measurement conditions and 180° in relation to the current level of technology. Of course, the reference angle θs may be set to 180° or more in line with future advancements in technology.

[0062] Next, we will describe the transformation forms of each component described so far.

[0063] Up to this point, we have described an example where the base end member 38 is a shaft member, but it may be replaced with a handle 32. It can also be said that there does not need to be any other shaft member between the intermediate shaft member 36 and the handle 32. When connecting the intermediate shaft member 36 to the base end member 38, which is the handle 32, any known connection means such as a clamp may be used. If there is no other shaft member on the base end side of the intermediate shaft member 36, the base end welding process as shown in Figure 5 above becomes unnecessary. In this case, the coil 42 may be embedded in the axial range from the tip to the base end of the intermediate shaft member 36, or it may be embedded only in a part of the axial range from the tip. In the latter case, the intermediate shaft member 36 having a location where the coil 42 is embedded and a location where the coil 42 is not embedded may be obtained by integral molding or the like.

[0064] An example has been described in which the intermediate shaft member 36 and the tip shaft member 40 are welded together with their end faces butted against each other. In addition, they may be welded together with the tip shaft member 40 overlapping the radially outer side of the intermediate shaft member 36. In this case, a tip boundary portion 52 is provided at the base end of the outer surface of the tip shaft member 40 between the intermediate shaft member 36 and the tip shaft member 40. If the base end member 38 is a shaft member, the base end member 38 and the intermediate shaft member 36 may be welded together with their end faces butted against each other. In this case, a base boundary portion 50 is provided at the point where their end faces butt against each other between the base end member 38 and the intermediate shaft member 36. The intermediate shaft member 36 may consist of only one resin layer or of three or more resin layers.

[0065] The reinforcing members 66A and 66B do not necessarily have to be located within a certain axial range of the thin-walled regions 64A and 64B. The ratio of the wall thickness t1 of the thick-walled region 62 to the wall thickness t2 of the thin-walled regions 64A and 64B is not particularly limited and may be greater than 1:3. The cannula 10 only needs to be equipped with at least one of the tip-side reinforcing member 66A and the proximal-side reinforcing member 66B. The cannula 10 may be equipped with only the tip-side reinforcing member 66A, or with only the proximal-side reinforcing member 66B.

[0066] The tip-side reinforcing member 66A does not necessarily have to be located 0.2 to 5.0 mm from the tip-side boundary 52 toward the base end. The tip-side reinforcing member 66A may be positioned to overlap radially with the tip-side boundary 52 of the tip-side shaft member 40. The tip-side reinforcing member 66A may be made of a material that is not radiopaque. The tip-side shaft member 40 may be provided with a marker portion. In this case, the marker portion may be made of a molded product using an radiopaque material and may be provided separately from the tip-side shaft member 40. Alternatively, the marker portion may be provided as part of the tip-side shaft member 40 by mixing a radiopaque material into the constituent material of the tip-side shaft member 40.

[0067] The base end reinforcing member 66B does not necessarily have to be located 0 to 1.0 mm from the base end boundary 50 towards the base end. The base end reinforcing member 66B may be positioned in an axial range that does not include the position P1 that overlaps radially with the base end boundary 50.

[0068] The contents of each component described in the embodiments above are illustrative. The abstract technical ideas derived from these should not be interpreted restrictively to the contents of this specification. Many design changes, such as modifications, additions, and deletions, are possible for each component described in the embodiments. Such design changes are emphasized by the notation "this form" or "embodiment." However, design changes are also permitted for contents without such notation. The hatching applied to the cross-sections in the drawings does not limit the material to which the hatching is applied. The structures and numerical values ​​mentioned in the embodiments and variations naturally include those that can be considered identical when considering manufacturing tolerances, etc. [Explanation of Symbols]

[0069] 10...cannula, 30...shaft, 36...intermediate shaft member, 38...proximal end member, 40...tip end shaft member, 42...coil, 44...resin layer, 50...proximal end boundary, 52...tip end boundary, 60...outer wall portion, 62...thick-walled region, 64A, 64B...thin-walled region, 66A...tip end reinforcing member, 66B...proximal end reinforcing member.

Claims

1. An intermediate shaft member in which a coil is embedded and whose shape can be adjusted by shaping, A base end member is positioned on the base end side of the intermediate shaft member and connected to the intermediate shaft member, The system comprises a tip-side shaft member that is positioned at the tip of the intermediate shaft member and connected to the intermediate shaft member, The intermediate shaft member is connected by welding to the base end member and the tip end shaft member, or both of the tip end shaft members, with the tip end shaft member as the welding partner. The shaft range is defined as the axial range from the boundary between the base end member and the outer surface of the intermediate shaft member to the boundary between the tip end member and the outer surface of the intermediate shaft member, and the cannula is provided with a reinforcing member positioned on the intermediate shaft member at at least one end of the shaft range that is near the welding mating surface.

2. The intermediate shaft member comprises at least one resin layer, The cannula according to claim 1, wherein the resin layer in which the coil is embedded is made of a polyolefin resin.

3. When the portion from the circumscribed circle that circumscribes the coil with respect to the center line of the lumen formed in the intermediate shaft member to the outer surface of the intermediate shaft member is referred to as the outer wall portion, the intermediate shaft member comprises a thick-walled region provided in the middle of the shaft range and a thin-walled region provided at the end of the shaft range in which the wall thickness of the outer wall portion is thinner than that of the thick-walled region, The cannula according to claim 1, wherein the reinforcing member is arranged in at least a portion of an axial range of the thin-walled region.

4. The cannula according to claim 3, wherein the ratio (= t1 / t2) of the thickness t1 of the outer portion of the thin-walled region to the thickness t2 of the outer portion of the thick-walled region is 1:3 or less.

5. The cannula according to claim 3, wherein the ratio of the thickness t1 of the outer portion of the thin-walled region to the thickness t3 of the intermediate shaft member (= t1 / t3) is 1:5 or less.

6. The cannula according to claim 1, wherein the reinforcing member includes a tip-side reinforcing member disposed at the tip of the shaft range in the intermediate shaft member.

7. The cannula according to claim 6, wherein the tip-side reinforcing member is provided at least in part at a position 0.2 to 5.0 mm from the tip-side boundary toward the base end.

8. The cannula according to claim 6, wherein the tip-side reinforcing member is provided at an axial distance from the tip-side shaft member.

9. The cannula according to claim 6, wherein the tip-side reinforcing member is made of a material that is impermeable to radiation.

10. The cannula according to claim 9, wherein the tip shaft member is not provided with a marker portion made of a material that is impermeable to radiation.

11. The base end member is a shaft member that constitutes the shaft, and is connected to the intermediate shaft member by welding. The cannula according to claim 1, wherein the reinforcing member includes a base-end reinforcing member disposed at the base end of the shaft range in the intermediate shaft member.

12. The cannula according to claim 11, wherein the proximal end reinforcing member is provided at least in part at a position 0 to 1.0 mm from the proximal end boundary toward the tip.

13. The tip of the base end member overlaps radially outward with respect to the base end of the intermediate shaft member. The cannula according to claim 11, wherein the base end reinforcing member is arranged in an axial range that includes a position that radially overlaps with the base end boundary.

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