Sheath and medical assembly

Abstract

To provide a sheath that can regulate radial shrinkage of a shaft part when a stylet is inserted, and is easily removed from the inside of a catheter.SOLUTION: A sheath 40 comprises: a main body part 41 extending in an axial direction; an insertion lumen 41L which is formed inside the main body part, and into which a stylet 50 is inserted; and a regulating part 43 for regulating radial shrinkage of a shaft part 33 while being inserted into the catheter.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a sheath and a medical assembly. [Background technology]

[0002] Percutaneous cardiopulmonary support (PCPS) has traditionally been used to provide cardiopulmonary resuscitation, circulatory support, and respiratory support in emergency care. PCPS is a method of temporarily supporting or substituting for cardiopulmonary function using an extracorporeal circulation device.

[0003] The extracorporeal circulation device includes an extracorporeal circulation circuit composed of a centrifugal pump, an artificial lung, a blood removal line, a blood transfer line, etc., and performs gas exchange on the removed blood before transferring it to the blood transfer line.

[0004] When blood is circulated through this circulation circuit, it is circulated by the power of a pump driven by a motor, so to ensure optimal blood circulation, it is necessary to reduce pressure loss in the tubes that make up the circulation circuit.

[0005] However, if the inner diameter of the tube is small, the pressure loss increases and the flow rate through the circulation circuit decreases. Therefore, if the inner diameter of the tube is not large enough, the required amount of blood circulation cannot be achieved.

[0006] On the other hand, increasing the inner diameter of a tube also increases the outer diameter of the tube. Therefore, if the inner diameter of a blood removal catheter (tube) or blood transfer catheter (tube) inserted into a patient's body is increased, the degree of invasiveness to the patient's body increases, and the burden on the patient's body increases.

[0007] In this regard, for example, Patent Document 1 listed below discloses a high-performance cannula in which the cannula body (catheter) can be expanded or contracted in the axial direction using a mandrel (stylet), thereby expanding or contracting its diameter. With a high-performance cannula configured in this manner, the cannula body is expanded in the axial direction using the mandrel to reduce its diameter (outer diameter), and then inserted into the living body, thereby reducing the degree of invasion into the patient's body. Furthermore, after the high-performance cannula is inserted into the living body, the cannula body contracts in the axial direction, increasing its diameter (inner diameter), by removing the mandrel. This reduces pressure loss in the catheter, ensuring the required flow rate of liquid. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 5059305 specification Summary of the Invention [Problem to be solved by the invention]

[0009] In the high-performance cannula disclosed in Patent Document 1, when a stylet is inserted into a catheter, the distal end (expansion section) is stretched axially and contracted radially inward. At this time, there is a risk that the insertion point (shaft section) located at the base end of the expansion section will also stretch axially and contract radially inward. When the shaft section contracts radially inward in this manner, frictional resistance with the stylet increases, preventing the stylet from being inserted to the desired position and preventing the expansion section from fully contracting radially inward. Inserting the expansion section into a living body in a state where it is not fully contracted radially inward increases the degree of invasiveness to the patient's body, which is undesirable.

[0010] On the other hand, if a stylet or other such component remains inserted in a catheter, the thickness of the tip of the stylet or other such component creates a step, which can cause blood retention and shear forces, potentially resulting in blood damage (thrombus, hemolysis). Furthermore, if a stylet or other such component remains inserted in a catheter, the lumen through which blood flows becomes smaller, resulting in pressure loss. For this reason, it is necessary to easily remove a long component such as a stylet from inside the catheter after the catheter has been positioned at the desired location.

[0011] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a sheath that can restrict radial contraction of the shaft portion when inserting a stylet and can be easily removed from inside the catheter. [Means for solving the problem]

[0012] A sheath that achieves the above object is a sheath that is detachably attached to a catheter having an axially extending shaft portion and a lumen through which blood can flow. The sheath includes an axially extending main body portion, an insertion lumen formed inside the main body portion and into which a stylet is inserted, and a restricting portion that restricts radial contraction of the shaft portion when inserted into the catheter. a first holding portion for holding the catheter in an inserted state; It has. The first holding portion is an elastic piece that can press the catheter radially inward. [Effects of the Invention]

[0013] With a sheath configured as described above, when a stylet is inserted into a catheter, the shaft portion attempts to contract radially inward, but the shaft portion comes into contact with the restricting portion, restricting this radially inward contraction of the shaft portion. In this state, by moving the stylet toward the distal end, the distal end of the tube extends in the axial direction and appropriately contracts radially inward. Furthermore, because the sheath is configured to be detachable from the catheter, it can be easily removed from inside the catheter. As described above, it is possible to provide a sheath that can restrict radial contraction of the shaft portion when inserting a stylet and that can be easily removed from inside the catheter. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a system diagram showing an example of an extracorporeal circulation device to which a percutaneous catheter according to an embodiment of the present invention is applied. [Figure 2] FIG. 2 is a side view showing the state before the sheath and stylet according to the present embodiment are inserted into the catheter. [Figure 3] FIG. 1 is a side cross-sectional view showing a catheter. [Figure 4] FIG. 10 is a schematic side view showing the state after the sheath and stylet according to the present embodiment have been inserted into the catheter. [Figure 5] FIG. 5(A) is a diagram for explaining the braid angle of the first reinforcing body, and FIG. 5(B) is a diagram for explaining the braid angle of the second reinforcing body. [Figure 6] FIG. 2 is a schematic cross-sectional view showing the configuration of a sheath according to the present embodiment. [Figure 7] 10A and 10B are diagrams for explaining how to use the sheath and stylet according to the present embodiment. [Figure 8] FIG. 2 is a plan view showing the state before the stylet according to the embodiment is inserted into the double lumen catheter. [Figure 9] FIG. 1 is a side cross-sectional view showing a double lumen catheter. [Figure 10] FIG. 10 is a schematic side view showing a sheath according to a modified example. [Figure 11] FIG. 10 is a schematic side view showing a stylet according to a modified example. [Figure 12] FIG. 10 is a schematic side view showing the state after a sheath and a stylet according to a modified example have been inserted into a catheter. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the following description does not limit the technical scope or meaning of terms described in the claims. Also, the dimensional proportions in the drawings are exaggerated for the convenience of explanation and may differ from the actual proportions.

[0016] FIG. 1 is a system diagram showing an example of an extracorporeal circulation device to which a percutaneous catheter according to an embodiment of the present invention is applied and which is used as percutaneous cardiopulmonary support (PCPS) to temporarily assist and substitute for the functions of the heart and lungs of a patient whose heart is weakened until cardiac function recovers.

[0017] The extracorporeal circulation device 1 can perform a veno-arterial (VA) procedure in which a pump is operated to withdraw blood from a patient's vein (vena cava), an artificial lung is used to exchange gases in the blood to oxygenate the blood, and the blood is then returned to the patient's artery (aorta). This extracorporeal circulation device 1 is a device that assists the heart and lungs. Hereinafter, the procedure of withdrawing blood from a patient, performing a prescribed treatment outside the body, and then returning the blood to the patient's body will be referred to as "extracorporeal circulation."

[0018] 1, the extracorporeal circulation device 1 has a circulation circuit for circulating blood. The circulation circuit has an oxygenator 2, a centrifugal pump 3, a drive motor 4 as a driving means for driving the centrifugal pump 3, a venous catheter (percutaneous catheter for blood removal) 5, an arterial catheter (catheter for blood supply) 6, and a controller 10 as a control unit.

[0019] A venous catheter (blood removal catheter) 5 is inserted through the femoral vein, and the tip of the venous catheter 5 is placed in the right atrium via the inferior vena cava. The venous catheter 5 is connected to the centrifugal pump 3 via a blood removal tube (blood removal line) 11. The blood removal tube 11 is a conduit for sending blood.

[0020] The arterial catheter (blood transfer catheter) 6 is inserted from the femoral artery.

[0021] When the drive motor 4 operates the centrifugal pump 3 in response to a command SG from the controller 10, the centrifugal pump 3 can draw blood from the blood removal tube 11, pass the blood through the oxygenator 2, and then return the blood to the patient P via the blood transfer tube (blood transfer line) 12.

[0022] The oxygenator 2 is disposed between the centrifugal pump 3 and the blood feed tube 12. The oxygenator 2 performs gas exchange (addition of oxygen and / or removal of carbon dioxide) with the blood. The oxygenator 2 is, for example, a membrane oxygenator, but a hollow fiber membrane oxygenator is particularly preferred. Oxygen gas is supplied to the oxygenator 2 from an oxygen gas supply unit 13 via a tube 14. The blood feed tube 12 is a conduit connecting the oxygenator 2 and the arterial catheter 6.

[0023] Pipes made of highly transparent, elastically deformable, flexible synthetic resin, such as polyvinyl chloride resin or silicone rubber, can be used for the blood removal tube 11 and the blood transfer tube 12. In the blood removal tube 11, blood, which is liquid, flows in the direction V1, and in the blood transfer tube 12, blood flows in the direction V2.

[0024] 1, an ultrasonic air bubble detection sensor 20 is disposed midway through the blood removal tube 11. A fast clamp 17 is disposed midway through the blood transfer tube 12.

[0025] The ultrasonic air bubble detection sensor 20 detects air bubbles that have been introduced into the circulation circuit during extracorporeal circulation due to erroneous operation of the three-way stopcock 18, tube damage, or the like. When the ultrasonic air bubble detection sensor 20 detects the presence of air bubbles in the blood being sent into the blood removal tube 11, the ultrasonic air bubble detection sensor 20 sends a detection signal to the controller 10. Based on this detection signal, the controller 10 issues an alarm and either reduces the rotation speed of the centrifugal pump 3 or stops the centrifugal pump 3. Furthermore, the controller 10 commands the fast clamp 17 to immediately close the blood transfer tube 12 with the fast clamp 17, thereby preventing air bubbles from being sent into the body of the patient P. The controller 10 controls the operation of the extracorporeal circulation device 1 to prevent air bubbles from entering the body of the patient P.

[0026] A pressure sensor is provided in the tube 11 (12, 19) of the circulation circuit of the extracorporeal circulation apparatus 1. The pressure sensor can be attached to, for example, any one or all of the following: attachment position A1 of the blood removal tube 11, attachment position A2 of the blood transfer tube 12 of the circulation circuit, or attachment position A3 of the connection tube 19 connecting the centrifugal pump 3 and the oxygenator 2. This allows the pressure sensor to measure the pressure inside the tube 11 (12, 19) when extracorporeal circulation is being performed for the patient P by the extracorporeal circulation apparatus 1. The attachment position of the pressure sensor is not limited to the above-mentioned attachment positions A1, A2, and A3, and it can be attached to any position in the circulation circuit.

[0027] Next, with reference to Figures 2 to 5, the configuration of a percutaneous catheter (hereinafter referred to as "catheter") 30 through which a sheath 40 and a stylet 50 (corresponding to a medical assembly) according to an embodiment of the present invention are inserted will be described. Figures 2 to 5 are diagrams provided for explaining the configuration of catheter 30. This catheter 30 is used as the venous catheter (catheter for blood removal) 5 in Figure 1. Note that the configuration of catheter 30 described below is one example, and the catheter through which a stylet 50 according to this embodiment is inserted is not limited to the following configuration.

[0028] As shown in Figure 2, the catheter 30 has a tube 31 having a first side hole 63 and a second side hole 46, a distal tip 49 disposed at the distal end of the tube 31 and having a through hole 47, a clamping tube 34 disposed on the proximal end side of the tube 31, a catheter connector 35 connecting the tube 31 and the clamping tube 34, and a lock connector 36.

[0029] In this specification, the side inserted into the living body is referred to as the "distal end" or "distal side," and the side operated by the surgeon is referred to as the "proximal end" or "proximal side." The distal end refers to a certain range including the distal end (the most distal end) and its surroundings, and the proximal end refers to a certain range including the proximal end (the most proximal end) and its surroundings.

[0030] 3, the catheter 30 has a lumen 30A that penetrates from the distal end to the proximal end. The through-hole 47 provided in the distal tip 49 and the first and second side holes 63 and 46 provided in the tube 31 are configured to be positioned at different blood removal targets within a living body to enable efficient blood removal.

[0031] When inserting the catheter 30 into a living body, the sheath 40 and stylet 50 shown in Figure 2 are used. The catheter 30, sheath 40, and stylet 50 are inserted into the living body in a state where they are previously integrated.

[0032] The following describes each component of the catheter 30. However, the configuration of the catheter 30 is not limited to the following.

[0033] As shown in FIG. 2, the tube 31 has an expansion portion 32 and a shaft portion 33 connected to the base end side of the expansion portion 32.

[0034] The expansion section 32 is configured to be more flexible than the shaft section 33. The expansion section 32 is also configured to have larger outer and inner diameters than the shaft section 33.

[0035] The lengths of the expansion section 32 and the shaft section 33 are configured to be lengths necessary for positioning the through-hole 47 of the distal tip 49 and the first side hole 63 and second side hole 46 of the tube 31 at the desired target for blood removal. The length of the expansion section 32 can be, for example, 20 to 40 cm, and the length of the shaft section 33 can be, for example, 20 to 30 cm.

[0036] In this embodiment, blood is removed from two locations: the right atrium and the inferior vena cava. The catheter 30 is inserted and placed in the living body so that the through-hole 47 of the distal tip 49 and the second side hole 46 of the tube 31 are positioned in the right atrium, and the first side hole 63 of the tube 31 is positioned in the inferior vena cava.

[0037] With the through hole 47, the second side hole 46, and the first side hole 63 positioned in the blood removal target, the expansion portion 32 is positioned in the inferior vena cava, which is a relatively large blood vessel, and the shaft portion 33 is positioned in the femoral vein, which is a relatively small blood vessel.

[0038] Furthermore, when the stylet 50 is inserted into the lumen 30A of the catheter 30, the highly elastic expansion section 32 stretches in the axial direction, reducing its outer and inner diameters, as shown in Figure 4. At this time, the outer diameter of the expansion section 32 becomes approximately the same as the outer diameter of the shaft section 33. Because the catheter 30 is inserted into the living body with the expansion section 32 stretched in the axial direction and its outer and inner diameters reduced, the catheter 30 can be inserted minimally invasively.

[0039] Furthermore, after the catheter 30 is placed in the living body, when the sheath 40 and stylet 50 are removed from the lumen 30A of the catheter 30, the expansion section 32 contracts from its axially extended state, increasing its inner diameter (see FIG. 7(D)). Here, the expansion section 32 is placed in the inferior vena cava, which is a relatively large blood vessel. Therefore, the outer diameter of the expansion section 32 can be increased, and therefore the inner diameter can be increased.

[0040] Here, the pressure loss inside the expansion section 32 is calculated as the total length of the expansion section 32 multiplied by the (average) cross-sectional area of the passage. That is, by increasing the inner diameter of the expansion section 32, the pressure loss inside the expansion section 32 is reduced. When the pressure loss inside the expansion section 32 is reduced, the flow rate of blood flowing through the circulation circuit increases. For this reason, in order to obtain a sufficient amount of blood circulation, it is necessary to increase the inner diameter of the expansion section 32.

[0041] On the other hand, if the wall thickness is approximately constant, increasing the inner diameter of the expansion section 32 and the shaft section 33 will increase the outer diameter, which will increase the burden on the patient when inserting the catheter 30 into the body and hinder minimally invasive procedures.

[0042] From the above viewpoints, the inner diameter of the extension portion 32 may be, for example, 9 to 11 mm, and the inner diameter of the shaft portion 33 may be, for example, 4 to 8 mm. The thickness of the extension portion 32 and the shaft portion 33 may be, for example, 0.4 to 0.5 mm.

[0043] 2, the distal end of the expansion section 32 preferably has a tapered section that gradually narrows from the center of the expansion section 32 toward the distal end in the axial direction, so that the inner diameter of the distal end of the expansion section 32 is continuous with the inner diameter of the distal tip 49 disposed on the distal end side.

[0044] As shown in Figure 5(A), the expansion portion 32 has a first reinforcing body 321 made of wires W braided in a crosswise manner, and a first resin layer 322 provided to cover the first reinforcing body 321.

[0045] As shown in Figure 5(B), the shaft portion 33 has a second reinforcing body 331 made of wire W braided in a crosswise manner, and a second resin layer 332 provided to cover the second reinforcing body 331.

[0046] As shown in Fig. 5(A), the first reinforcing body 321 is configured by braiding wire W at a braiding angle θ1, and as shown in Fig. 5(B), the second reinforcing body 331 is configured by braiding wire W at a braiding angle θ2.

[0047] In this specification, the braiding angles θ1 and θ2 are defined as the interior angles in the axial direction among the angles formed by the intersecting wires W, as shown in FIGS. 5(A) and 5(B).

[0048] 5(A) and 5(B), the braiding angle θ1 of the first reinforcing body 321 is configured to be smaller than the braiding angle θ2 of the second reinforcing body 331. Therefore, the inclination angle of the wires W constituting the first reinforcing body 321 with respect to the axial direction is smaller compared to when the braiding angle of the first reinforcing body 321 is larger than the braiding angle of the second reinforcing body 331. Note that the braiding angle θ1 of the first reinforcing body 321 may be configured to be larger than the braiding angle θ2 of the second reinforcing body 331.

[0049] Here, as the expansion section 32 expands in the axial direction, the wire W constituting the first reinforcing body 321 of the expansion section 32 deforms so that the inclination angle with respect to the axial direction gradually decreases. Then, when the inclination angle with respect to the axial direction of the wire W constituting the first reinforcing body 321 of the expansion section 32 becomes approximately zero, the expansion of the expansion section 32 in the axial direction is restricted.

[0050] Therefore, by configuring the braiding angle θ1 of the first reinforcement body 321 to be smaller than the braiding angle θ2 of the second reinforcement body 331, the extension distance along the axial direction of the expansion section 32 associated with inserting the stylet 50 into the catheter 30 is shorter than when the braiding angle of the first reinforcement body 321 is larger than the braiding angle of the second reinforcement body 331.

[0051] The braiding angle θ1 of the first reinforcing member 321 is not particularly limited, but is in the range of 100 degrees to 120 degrees. The braiding angle θ2 of the second reinforcing member 331 is not particularly limited, but is in the range of 130 degrees to 150 degrees. By making the braiding angle θ2 of the second reinforcing member 331 larger than the braiding angle θ1 of the first reinforcing member 321 in this way, the kink resistance of the second reinforcing member 331 can be improved. This allows the catheter 30 to be suitably inserted into the living body through the femoral vein, which has a complex structure.

[0052] 5(A) and 5(B), the first reinforcing body 321 of the expansion section 32 is braided more loosely than the second reinforcing body 331 of the shaft section 33. This configuration makes the expansion section 32 softer than the shaft section 33, thereby increasing its stretchability.

[0053] In this embodiment, the wire W is made of a shape-memory material such as a known shape-memory metal or shape-memory resin. Examples of shape-memory metals that can be used include titanium-based alloys (Ni-Ti, Ti-Pd, Ti-Nb-Sn, etc.) and copper-based alloys. Examples of shape-memory resins that can be used include acrylic resins, transisoprene polymers, polynorbornene, styrene-butadiene copolymers, and polyurethanes.

[0054] Because the wire W is made of a shape memory material, the axial contraction distance of the expansion portion 32 associated with removing the stylet 50 from the catheter 30 is the same as the axial extension distance of the expansion portion 32 associated with inserting the stylet 50 through the catheter 30.

[0055] The diameter of the wire W is preferably 0.1 mm to 0.2 mm.

[0056] By making the wire diameter of the wire W 0.1 mm or more, the wire W can suitably exhibit its function as a reinforcing member that improves strength.

[0057] On the other hand, by setting the wire diameter of the wire W to 0.2 mm or less, it is possible to reduce the outer diameter of the expansion section 32 while increasing the inner diameter, thereby reducing the burden on the patient's body and reducing pressure loss when inserting the catheter 30. In this embodiment, the cross section of the wire W is circular, but is not limited to this and may be rectangular, square, elliptical, or the like.

[0058] The first resin layer 322 of the extension portion 32 is made of a softer material with lower hardness than the second resin layer 332 of the shaft portion 33. With this configuration, the extension portion 32 can be made softer than the shaft portion 33, and the stretchability can be improved.

[0059] The first and second resin layers 322, 332 can be formed using vinyl chloride, silicone, polyethylene, nylon, urethane, polyurethane, fluororesin, thermoplastic elastomer resin, or the like, or using a composite material of these.

[0060] Silicone material has the advantage of being highly biocompatible and soft, making it less likely to damage blood vessels. Polyethylene material is soft yet hard enough to withstand pressure. Moreover, polyethylene material has biocompatibility comparable to that of silicone material. Polyethylene material is harder than silicone, making it easier to insert into thin blood vessels. Polyurethane material also has the advantage of becoming soft after insertion. Applicable materials can be used for the first and second resin layers 322, 332, taking advantage of the advantages of these materials.

[0061] Alternatively, a hydrophilic coating can be applied to the polyurethane material. This makes the tube surface smooth, making it easier to insert into the blood vessel and less likely to damage the blood vessel wall. It is also expected that blood and protein will not adhere to the tube, preventing the formation of blood clots.

[0062] The method for forming the extension portion 32 and the shaft portion 33 is not particularly limited, but they can be formed by, for example, dip coating (immersion method), insert molding, etc. It is sufficient that at least the outer surfaces of the reinforcing bodies 321 and 331 are covered with the resin layers 322 and 332.

[0063] As shown in Figure 2, the expansion section 32 has second side holes 46. As shown in Figure 2, multiple second side holes 46 (four in Figure 2) are provided along the axial direction. It is preferable that multiple second side holes 46 are also provided in the circumferential direction. The second side holes 46 function as blood removal holes.

[0064] As shown in FIG. 2, the shaft portion 33 has a first side hole 63. The first side hole 63 functions as a blood removal hole. It is preferable to have a plurality of first side holes 63 in the circumferential direction. In the present embodiment, four first side holes 63 are provided in the shaft portion 33 in the circumferential direction. As a result, even if one first side hole 63 is adsorbed to the blood vessel wall and blocked during blood removal, blood removal can still be performed through the other first side holes 63, and blood circulation can be stabilized.

[0065] 2 to 4, the distal tip 49 is disposed at the distal end of the expansion portion 32. The distal tip 49 has a tapered shape with a diameter that gradually decreases toward the distal end.

[0066] The distal tip 49 has a flat receiving surface 48 formed on the inside thereof, which comes into contact with a flat surface 50a of a stylet 50 that is used prior to inserting the catheter 30 into a living body.

[0067] As shown in Figure 3, the distal tip 49 is configured to accommodate the distal end of the wire W. The distal tip 49 has a through-hole 47. The through-hole 47 functions as a hole for blood removal. The through-hole 47 of the distal tip 49 forms part of the lumen 30A of the catheter 30. The distal tip 49 can be made of, for example, urethane.

[0068] By fixing the hard distal tip 49 to the distal end of the expansion part 32, it is possible to effectively prevent the expansion part 32 from collapsing during blood removal.

[0069] As shown in FIGS. 2 to 4, the clamping tube 34 is provided on the proximal end side of the shaft portion 33. A lumen through which the stylet 50 can be inserted is provided inside the clamping tube 34. The clamping tube 34 can be formed using the same material as the tube 31.

[0070] 2 and 4, catheter connector 35 connects shaft portion 33 and clamp tube 34. Inside catheter connector 35, a lumen is provided through which stylet 50 can be inserted.

[0071] As shown in FIGS. 2 to 4, the lock connector 36 is connected to the proximal end side of the clamp tube 34. A lumen through which a stylet 50 can be inserted is provided inside the lock connector 36. A male threaded portion 36A having a thread is provided on the outer surface of the proximal end side of the lock connector 36. As shown in FIGS. 4 and 6, the male threaded portion 36A is fitted into and held by the first holding portion 44 of the sheath 40.

[0072] Next, the configuration of the sheath 40 according to this embodiment will be described with reference to Fig. 6 etc. Fig. 6 is a diagram provided for explaining the configuration of the sheath 40 according to this embodiment.

[0073] The sheath 40 is configured to be detachable from the catheter 30. As shown in Figure 6, the sheath 40 has a main body portion 41 extending in the axial direction and a holding portion 42 provided on the proximal end side of the main body portion 41.

[0074] The outer periphery of the main body 41 is configured as a restricting portion 43 that restricts radial contraction of the shaft 33 when the sheath 40 is inserted into the catheter 30. The restricting portion 43 is configured by setting the hardness of the main body 41 to be greater than the hardness of the shaft 33.

[0075] An insertion lumen 41L, into which a stylet 50 is inserted, is formed on the inner periphery of the main body 41. The distal end 41A of the main body 41 is configured to be tapered, as shown in FIG. 6. This configuration improves the ease of inserting the sheath 40 into the catheter 30. Furthermore, this configuration prevents the formation of a step when the expansion section 32 of the tube 31 is extended in the axial direction by the stylet 50 (see FIG. 7(C)), as the expansion section 32 deforms to fit the shape of the distal end 41A of the main body 41.

[0076] When the sheath 40 is set in the catheter 30 (see FIG. 7(A)), the tip portion 41A of the main body portion 41 is disposed inside the expansion portion 32. With this configuration, in the state shown in FIG. 7(A), it is possible to prevent the expansion portion 32 from unintentionally sagging down during use.

[0077] Furthermore, with this configuration, the lumen surface of the catheter 30 is protected by the sheath 40, so that when the stylet 50 is inserted, the lumen surface of the catheter 30 can be prevented from being damaged by the tip of the stylet.

[0078] The material for forming the main body 41 is not particularly limited, but may be the same as that for the first and second resin layers 322 and 332 described above.

[0079] As shown in FIG. 6, the holding portion 42 is composed of a single component, and has a first holding portion 44 for maintaining the sheath 40 inserted into the catheter 30, a second holding portion 45 for maintaining the stylet 50 inserted into the insertion lumen 41L, and a partition portion 42A interposed between the first holding portion 44 and the second holding portion 45.

[0080] The first holding portion 44 is an elastic piece that can press the male thread portion 36A of the catheter 30 radially inward. The second holding portion 45 is an elastic piece that can press the stylet hub 52 of the stylet 50 radially inward. The holding force of the second holding portion 45 is greater than the holding force of the first holding portion 44. With this configuration, as shown in FIG. 7(D), by pulling the stylet hub 52 toward the proximal end, the sheath 40 and stylet 50 can be removed from the catheter 30 while maintaining the connection between the sheath 40 and stylet 50.

[0081] Furthermore, a partition 42A is interposed between the first holding part 44 and the second holding part 45. This partition 42A prevents the holding force of the second holding part 45 from being transmitted to the first holding part 44 when the second holding part 45 is held, and therefore prevents the first holding part 44 from opening (i.e., the holding of the catheter 30 being released).

[0082] The inner diameter of the second holding part 45 expands axially toward the base end, making it easier to insert the stylet hub 52 and to grasp the stylet hub 52 together with the second holding part 45. Furthermore, when removing the stylet 50 from the second holding part 45, the second holding part 45 opens in the direction that increases its expanded diameter, making it easy to attach and detach the stylet 50.

[0083] The retaining portion 42 is made of, for example, rubber and has elasticity. However, the retaining portion 42 is not limited to rubber as long as it has the ability to retain, and may be made of any material that allows the male thread portion 36A of the catheter 30 and the stylet hub 52 of the stylet 50 to be tightly fitted together.

[0084] Next, returning to FIG. 2, the configuration of the stylet 50 according to this embodiment will be described.

[0085] As shown in FIG. 2, the stylet 50 has a stylet tube 51 extending in the axial direction, and a stylet hub 52 to which the proximal end of the stylet tube 51 is fixed.

[0086] The stylet tube 51 is a long, relatively rigid body that extends in the axial direction. The overall axial length of the stylet tube 51 is configured to be substantially the same as the overall axial length of the catheter 30. The stylet tube 51 is provided with a guidewire lumen 54 through which a guidewire (not shown) can be inserted. The stylet tube 51 is guided by the guidewire and inserted into a living body together with the sheath 40 and the catheter 30. After the catheter 30 has been placed in the living body, the stylet tube 51 is removed from the catheter 30 together with the sheath 40 by pulling the stylet hub 52 toward the proximal end.

[0087] The stylet tube 51 has a relatively high rigidity, providing the strength to transmit a pushing force toward the distal end caused by hand manipulation to the tube 31. Therefore, the stylet tube 51 plays a role in dilating a narrow blood vessel by being pushed toward the distal end while fixed to the catheter 30. Furthermore, the hardness of the stylet tube 51 is preferably less than the hardness of the main body portion 41 of the sheath 40. With this configuration, as shown in FIG. 7 , the portion where the stylet tube 51 is exposed from the main body portion 41 can be made flexible, while the portion where the stylet tube 51 is disposed inside the main body portion 41 can be made rigid. This improves operability.

[0088] The tip 52A of the stylet hub 52 has an outer diameter slightly larger than the inner diameter of the second holding portion 45 of the holding part 42. By pushing the tip 52A of the stylet hub 52 into the second holding portion 45, the stylet 50 can be held in the sheath 40.

[0089] <How to use the sheath and stylet> Next, a method of using the above-described sheath 40 and stylet 50 will be described with reference to Fig. 7. Fig. 7 is a diagram for explaining a method of using the sheath 40 and stylet 50 according to this embodiment. Note that in Fig. 7, the wire W, first side hole 63, second side hole 46, etc. of the catheter 30 are not shown.

[0090] First, as shown in Figure 7(A), the sheath 40 is set on the catheter 30. Specifically, the sheath 40 is inserted into the lumen 30A of the catheter 30. At this time, the sheath 40 passes through the shaft portion 33 and the interior of the expansion portion 32, in that order. Then, the male thread portion 36A of the lock connector 36 of the catheter 30 is fitted into and held in the first holding portion 44 of the holding portion 42 of the sheath 40. At this time, the tip portion 41A of the main body portion 41 of the sheath 40 is positioned inside the expansion portion 32, which prevents the expansion portion 32 from unintentionally sagging, thereby reducing the risk of the catheter tip coming into contact with the floor, etc., and becoming contaminated.

[0091] 7(B), the stylet 50 is inserted into the lumen 30A of the catheter 30 in which the sheath 40 is set. The stylet 50 passes through the shaft portion 33 and the expansion portion 32 in that order, and the flat surface 50a of the stylet 50 abuts against the receiving surface 48 of the distal tip 49.

[0092] 2, the overall axial length of the stylet 50 is longer than the overall axial length of the catheter 30 before the expansion section 32 is extended. Therefore, with the flat surface 50a of the stylet 50 in contact with the receiving surface 48 of the distal tip 49, the expansion section 32 is pressed toward the distal end.

[0093] 7(C), the tip of the expansion section 32 is pulled toward the tip. As a result, the catheter 30 is subjected to a force that stretches it in the axial direction, and the expansion section 32, which has relatively high elasticity within the catheter 30, stretches in the axial direction. Furthermore, the shaft section 33 attempts to contract radially inward, but the restricting section 43 of the sheath 40 can prevent the shaft section 33 from contracting radially inward. In this state, by moving the stylet 50 toward the tip, the expansion section 32 stretches in the axial direction and preferably contracts radially inward.

[0094] Thereafter, as shown in FIG. 7(C), the stylet hub 52 of the stylet 50 is fitted into the second holding portion 45 of the holding portion 42 of the sheath 40, thereby attaching the stylet 50 to the sheath 40 and the catheter 30.

[0095] Next, the catheter 30 with the sheath 40 and stylet 50 fixed thereto is inserted along a guide wire (not shown) that has been inserted into the target site in the living body beforehand. At this time, because the stylet 50 is inserted through the catheter 30, the outer diameter of the expansion section 32 is approximately the same as the outer diameter of the shaft section 33, allowing the catheter 30 to be inserted into the living body in a minimally invasive manner, thereby reducing the burden on the patient's body.

[0096] Furthermore, the catheter 30 is inserted into the living body and left in place until the through-hole 47 of the distal tip 49 and the second side hole 46 of the tube 31 are positioned in the right atrium, and the first side hole 63 of the tube 31 is positioned in the inferior vena cava. With the through-hole 47, the first side hole 63, and the second side hole 46 positioned in the blood removal target, the expansion section 32 is positioned in the inferior vena cava, which is a relatively large blood vessel, and the shaft section 33 is positioned in the femoral vein, which is a relatively small blood vessel.

[0097] Next, the sheath 40, stylet 50, and guidewire are removed from the catheter 30. At this time, the holding force of the second holding section 45 is greater than the holding force of the first holding section 44, so by pulling out the stylet hub 52 toward the proximal end, as shown in Figure 7(D), the sheath 40 and stylet 50 can be removed from the catheter 30 while maintaining the connected state of the sheath 40 and stylet 50.

[0098] The sheath 40, stylet 50, and guidewire are first withdrawn to the clamping tube 34 of the catheter 30 and clamped with forceps (not shown), and then completely removed from the catheter 30. By removing the sheath 40 and stylet 50 from the lumen of the catheter 30, the catheter 30 is released from the axially stretching force that the catheter 30 has been receiving from the stylet 50. This causes the expansion section 32 to contract axially, increasing its inner diameter. This reduces pressure loss within the expansion section 32 and ensures the required flow rate of liquid.

[0099] Next, the lock connector 36 of the catheter 30 is connected to the blood removal tube 11 of the extracorporeal circulation device shown in Figure 1. After confirming that the connection of the blood supply catheter is complete, the clamp on the clamping tube 34 is released to start extracorporeal circulation.

[0100] After the extracorporeal circulation is completed, the catheter 30 is removed from the blood vessel, and the insertion site is surgically repaired for hemostasis, if necessary.

[0101] As described above, the sheath 40 according to this embodiment is configured to be detachably attached to a catheter 30 having an axially extending shaft portion 33 and a lumen 30A through which blood can flow. The sheath 40 includes an axially extending main body portion 41, an insertion lumen 41L formed within the main body portion 41 and into which the stylet 50 is inserted, and a restricting portion 43 that restricts radial contraction of the shaft portion 33 when inserted into the catheter 30. With the sheath 40 configured in this manner, when the stylet 50 is inserted into the catheter 30, the shaft portion 33 attempts to contract radially inward, but the shaft portion 33 comes into contact with the restricting portion 43, restricting this radially inward contraction of the shaft portion 33. In this state, by moving the stylet 50 toward the distal end, the distal end of the tube 31 extends axially and appropriately contracts radially inward. Furthermore, because the sheath 40 is configured to be detachable from the catheter 30, it can be easily removed from inside the catheter 30. As described above, it is possible to provide a sheath 40 that can restrict radial contraction of the shaft portion 33 when inserting the stylet 50 and can be easily removed from inside the catheter 30.

[0102] Furthermore, the sheath 40 according to this embodiment has a first holding portion 44 for maintaining the inserted state relative to the catheter 30, and a second holding portion 45 for maintaining the inserted state of the stylet 50 relative to the insertion lumen 41L. With a sheath 40 configured in this manner, the sheath 40 and stylet 50 can be suitably fixed to the catheter 30, improving operability when inserting the sheath 40, stylet 50, and catheter 30 into a blood vessel.

[0103] Furthermore, the first holding portion 44 is an elastic piece that can press the catheter 30 radially inward. With this simple configuration, the inserted state of the sheath 40 in the catheter 30 can be maintained.

[0104] Additionally, the second holding portion 45 is an elastic piece that can press the stylet 50 radially inward. This simple configuration makes it possible to maintain the stylet 50 inserted into the insertion lumen 41L.

[0105] Furthermore, the holding force of the second holding portion 45 is greater than the holding force of the first holding portion 44. With this configuration, as shown in Figure 7(D), by pulling the stylet hub 52 toward the proximal end, the sheath 40 and stylet 50 can be removed from the catheter 30 while maintaining the connected state of the sheath 40 and stylet 50. This improves operability during the procedure.

[0106] Furthermore, the restricting portion 43 is configured such that the hardness of the main body portion 41 is greater than the hardness of the shaft portion 33. According to this configuration, the restricting portion 43 can be configured with a simple structure.

[0107] Furthermore, the tip portion 41A of the main body 41 is located inside the expansion portion 32 formed on the tip side of the shaft portion 33 of the catheter 30. The sheath 40 configured in this manner can prevent the expansion portion 32 from unintentionally drooping, reducing the risk of contamination of the catheter tip.

[0108] <Modified Catheter> Next, modified examples of the catheter will be described. In the above-described embodiment, the sheath 40 and stylet 50 are applied to a catheter 30 having one lumen 30A. However, they can also be used for a catheter 60 having double lumens, as shown in Figures 8 and 9. The configuration of a catheter 60 having double lumens will be described below with reference to Figures 8 and 9.

[0109] The catheter 60 is a so-called double lumen catheter, which is capable of both blood feeding and blood removal at the same time. Therefore, in this embodiment, the extracorporeal circulation device of Fig. 1 does not use two catheters, a venous catheter (blood removal catheter) 5 and an arterial catheter (blood feed catheter) 6, but instead uses only one catheter 60 to perform the procedure.

[0110] As shown in FIGS. 8 and 9, the catheter 60 has a double-tube structure in which a third tube 161 having a first lumen 61 communicating with a blood feed side hole 163 is disposed in the inner cavity of the shaft portion 133.

[0111] The catheter 60 enables veno-venous (VV) extracorporeal blood circulation using an artificial lung, in which blood is drawn from the patient's vein (vena cava) by operating the pump of the extracorporeal circulation device, gas exchange is carried out in the blood using an artificial lung to oxygenate the blood, and the blood is then returned to the patient's vein (vena cava).

[0112] 8 and 9, the catheter 60 has an expansion section 32, a shaft section 133, a distal tip 49 disposed at the distal end of the expansion section 32, and a third tube 161 disposed in the lumen of the shaft section 133. The configurations of the expansion section 32 and the distal tip 49 are the same as those of the catheter 30 of the first embodiment, and therefore description thereof will be omitted.

[0113] As shown in FIG. 9, the catheter 60 has a first lumen 61 that functions as a blood feed channel and a second lumen 62 that functions as a blood removal channel.

[0114] The first lumen 61 is formed in the inner cavity of the third tube 161. The second lumen 62 is formed in the inner cavities of the expansion portion 32 and the shaft portion 133, and passes through from the distal end to the proximal end.

[0115] The shaft portion 133 is provided with a blood feed side hole 163 that communicates with the first lumen 61, which is a blood feed path.

[0116] The shaft portion 133 is provided with a blood removal side hole 164 that communicates with the second lumen 62, which is the blood removal path.

[0117] The blood feed side hole 163 and the blood removal side hole 164 are configured in an elliptical shape.

[0118] The third tube 161 is inserted into the second lumen 62 from the base end side of the shaft portion 133 and is connected to the blood feed side hole 163 .

[0119] The blood feed side hole 163 is placed at a blood feed target inside the living body, and blood that has been oxygenated by the artificial lung is fed into the living body through the blood feed side hole 163.

[0120] The through-hole 47 of the distal tip 49, the second side hole 46 of the expansion section 32, and the blood removal side hole 164 of the shaft section 133 are configured to enable efficient blood removal when placed at different blood removal targets within a living body. Furthermore, even if the through-hole 47, the second side hole 46, or the blood removal side hole 164 is adsorbed to the blood vessel wall and blocked, blood removal can be performed from the unblocked hole, allowing stable extracorporeal circulation.

[0121] In this embodiment, the catheter 60 is inserted through the internal jugular vein in the neck, passes through the superior vena cava and the right atrium, and its tip is placed in the inferior vena cava. The target for blood supply is the right atrium, and the targets for blood removal are the superior vena cava and the inferior vena cava.

[0122] With the sheath 40 and stylet 50 inserted, the catheter 60 is inserted and placed in the living body so that the through hole 47 of the distal tip 49 and the second side hole 46 of the expansion section 32 are positioned in the inferior vena cava, and the blood removal side hole 164 of the shaft section 133 is positioned in the internal jugular vein.

[0123] The expansion section 32 is configured to have a larger inner diameter than the shaft section 133. With the through-hole 47, the second side hole 46, and the blood removal side hole 164 positioned in the blood removal target, the expansion section 32 is positioned in the inferior vena cava, which is a relatively thick blood vessel, and the shaft section 133 is positioned in the femoral vein, which is a relatively thin blood vessel.

[0124] 9, lock connector 136 has a first lock connector 137 that communicates with first lumen 61, and a second lock connector 138 that is provided in parallel to first lock connector 137 and communicates with second lumen 62. Lock connector 136 is a Y-shaped Y connector formed by first lock connector 137 branching off from second lock connector 138.

[0125] The first lock connector 137 is connected to the base end of the third tube 161. The second lock connector 138 is coaxially connected to the base end of the shaft portion 133. A blood transfer tube (blood transfer line) is connected to the first lock connector 137, and a blood removal tube (blood removal line) is connected to the second lock connector 138.

[0126] As described above, the catheter 60 according to this embodiment can perform both the functions of blood removal and blood transfer with a single catheter.

[0127] The catheter according to the present invention has been described above through the embodiments, but the present invention is not limited to the configurations described in the embodiments and modifications, and can be modified as appropriate based on the claims.

[0128] For example, in the above-described embodiment, the first holding portion 44 is an elastic piece that can press the tube 31 radially inward. However, the first holding portion may be a female thread portion that can be threaded onto the male thread portion 36A of the lock connector 36.

[0129] Furthermore, the material constituting the wire W is not limited to a shape-memory material as long as it has the restoring force to return to its original shape after being deformed and has the function of reinforcing the resin layer, and can be made of, for example, a known elastic material.

[0130] Furthermore, in the above-described embodiment, the holding force of the second holding portion 45 is greater than the holding force of the first holding portion 44, but the holding force of the second holding portion 45 may be less than the holding force of the first holding portion 44. In this case, when removing the sheath 40 and the stylet 50, the sheath 40 and the stylet 50 are removed while holding the stylet 50 with a hand to prevent it from coming out of the second holding portion 45.

[0131] In the above-described embodiment, the catheter 30 is described as having an expansion portion 32. However, the catheter may have a configuration that does not have an expansion portion.

[0132] Alternatively, the sheath 140 may have a holder 141 as shown in Fig. 10, and the stylet 150 may have a hub 151 as shown in Fig. 11. In this configuration, the sheath 140 is slidably inserted into the catheter 30 as shown in Fig. 12, but the holder 141 restricts movement of the sheath 140 toward the distal end of the catheter 30 in the axial direction. As shown in Fig. 12, the stylet 150 is inserted from the proximal end side of the sheath 140 and fixed to the catheter 30 by, for example, threading, thereby fixing the sheath 140 to the proximal end of the catheter 30. Since the catheter 30 and the stylet 150 are fitted together by the holder 141, the sheath 140 can be easily removed when removing the stylet 150. [Explanation of symbols]

[0133] 30, 60 catheters (percutaneous catheters), 30A lumens, 31 catheter tube (tube), 32 extension, 33, 133 shaft part, 36A male thread, 40, 140 sheath, 41 main body, 41A Tip of the main body, 41L insertion lumen, 43 Regulatory Department, 44 1st holding part, 45 Second holding part, 50, 150 スタイレット.

Claims

1. A sheath configured to be detachable from a catheter having a shaft portion extending in an axial direction and a lumen through which blood can flow, a main body portion extending in an axial direction; an insertion lumen formed inside the main body portion and into which a stylet is inserted; a restricting portion that restricts radial contraction of the shaft portion when the shaft portion is inserted into the catheter; a first holding portion for holding the catheter in an inserted state, The first holding portion is a sheath that is an elastic piece that can press the catheter radially inward.

2. Further having a second holding portion for holding the stylet inserted into the insertion lumen, The sheath according to claim 1 , wherein the second holding portion is an elastic piece that can press the stylet radially inward.

3. The sheath of claim 2 , wherein the second retaining portion has a greater retaining force than the first retaining portion.

4. The sheath according to any one of claims 1 to 3, wherein the restricting portion is configured such that the hardness of the main body portion is greater than the hardness of the shaft portion.

5. The sheath according to any one of claims 1 to 4, wherein the distal end of the main body is located inside an expansion section formed on the distal end side of the shaft section of the catheter.

6. The sheath according to any one of claims 1 to 5, the stylet inserted into the insertion lumen of the sheath.

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