JP7723536B2 - Sheath and medical assembly - Google Patents

Description

The present invention relates to a sheath and a medical assembly.

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.

An extracorporeal circulation device has an extracorporeal circulation circuit consisting of a centrifugal pump, an artificial lung, a blood removal line, and a blood return line, and performs gas exchange on the removed blood before sending it to the blood return line.

When blood circulates in this circulation circuit, it is circulated using the power of a pump driven by a motor. Therefore, to ensure optimal blood circulation, it is necessary to reduce pressure loss in the tubes that make up the circulation circuit.

However, if the inner diameter of the tube is small, the pressure loss will be high and the flow rate through the circulation circuit will decrease. Therefore, if the inner diameter of the tube is not large enough, the required amount of blood will not be circulated.

On the other hand, increasing the inner diameter of a tube also increases its outer diameter. Therefore, increasing the inner diameter of a blood removal catheter (tube) or blood transfer catheter (tube) inserted into a patient's body increases the degree of invasiveness to the patient's body, placing a greater strain on the patient's body.

In this regard, for example, Patent Document 1 below discloses a high-performance cannula in which the cannula body (catheter) can be expanded or contracted axially using a mandrel (stylet), thereby expanding or contracting its diameter. With a high-performance cannula configured in this manner, the cannula body is expanded axially using the mandrel to reduce its diameter (outer diameter), and then inserted into the body, thereby reducing the degree of invasiveness to the patient's body. Furthermore, after the high-performance cannula is inserted into the body, removing the mandrel causes the cannula body to contract axially, increasing its diameter (inner diameter). This reduces pressure loss in the catheter, ensuring the required fluid flow rate.

Patent No. 5059305 specification

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 way, 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. Furthermore, inserting the expansion section into a living body in a state where it has not fully contracted radially inward increases the degree of invasiveness to the patient's body, which is undesirable.

However, if a stylet or other such device remains inserted in a catheter, the thickness of the tip of the stylet or other such device can cause unevenness in the thickness of the tip, which can lead to blood retention and shear forces, potentially resulting in blood damage (thrombus, hemolysis). Furthermore, if a stylet or other such device 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 member such as a stylet from inside the catheter after the catheter has been positioned at the desired location.

The present invention was made to solve the above problems, and aims 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.

A sheath that achieves the above-mentioned object is a sheath configured to be detachable from a catheter having an axially extending shaft portion and a lumen through which blood can flow. The sheath has an axially extending main body portion, 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 inserted into the catheter, and a first holding portion that maintains the inserted state relative to the catheter . The first holding portion is an elastic piece that can press the catheter radially inward.

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 radial inward contraction. In this state, by moving the stylet toward the distal end, the distal end of the tube extends axially 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 a result, a sheath can be provided that can restrict the radial contraction of the shaft portion when inserting a stylet, and that can be easily removed from inside the catheter.

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. FIG. 2 is a side view showing the state before the sheath and stylet according to the present embodiment are inserted into the catheter. FIG. 1 is a side cross-sectional view showing a catheter. 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. 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. FIG. 2 is a schematic cross-sectional view showing the configuration of a sheath according to the present embodiment. 10A and 10B are diagrams for explaining how to use the sheath and stylet according to the present embodiment. FIG. 2 is a plan view showing the state before the stylet according to the embodiment is inserted into the double lumen catheter. FIG. 1 is a side cross-sectional view showing a double lumen catheter. FIG. 10 is a schematic side view showing a sheath according to a modified example. FIG. 10 is a schematic side view showing a stylet according to a modified example. 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.

Embodiments of the present invention will now be described with reference to the accompanying drawings. Note that the following description does not limit the technical scope or the meaning of terms described in the claims. Also, the dimensional proportions in the drawings have been exaggerated for the sake of explanation and may differ from the actual proportions.

Figure 1 is a system diagram showing an example of an extracorporeal circulation device that uses a percutaneous catheter according to an embodiment of the present invention and is used as percutaneous cardiopulmonary support (PCPS), which temporarily supports and substitutes for the function of the heart and lungs of a patient whose heart is weakened until cardiac function recovers.

The extracorporeal circulation device 1 enables venous-arterial (VA) procedures, in which a pump is operated to draw blood from a patient's veins (vena cava), an artificial lung is used to exchange gases within the blood to oxygenate the blood, and the blood is then returned to the patient's arteries (aorta). This extracorporeal circulation device 1 is a device that assists the heart and lungs. Hereinafter, the procedure of drawing 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."

As shown in Figure 1, the extracorporeal circulation device 1 has a circulation circuit for circulating blood. The circulation circuit includes 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.

The 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.

The arterial catheter (blood transfer catheter) 6 is inserted through the femoral artery.

When the drive motor 4 operates the centrifugal pump 3 in response to a command SG from the controller 10, the centrifugal pump 3 draws blood from the blood removal tube 11, passes the blood through the oxygenator 2, and then returns the blood to the patient P via the blood transfer tube (blood transfer line) 12.

The oxygenator 2 is positioned between the centrifugal pump 3 and the blood supply tube 12. The oxygenator 2 performs gas exchange (oxygen addition and/or carbon dioxide removal) 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 the oxygen gas supply unit 13 via the tube 14. The blood supply tube 12 is a conduit connecting the oxygenator 2 to the arterial catheter 6.

The blood removal tube 11 and blood transfer tube 12 can be made of highly transparent, elastically deformable, flexible synthetic resin pipes such as polyvinyl chloride resin or silicone rubber. In the blood removal tube 11, liquid blood flows in the direction V1, while in the blood transfer tube 12, blood flows in the direction V2.

In the circulation circuit shown in Figure 1, the ultrasonic air bubble detection sensor 20 is located midway through the blood removal tube 11. The fast clamp 17 is located midway through the blood transfer tube 12.

The ultrasonic air bubble detection sensor 20 detects air bubbles that have been introduced into the circulation circuit during extracorporeal circulation due to incorrect operation of the three-way stopcock 18, tube damage, etc. If 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 return tube 12 with the fast clamp 17, thereby preventing air bubbles from being sent into the patient P's body. The controller 10 controls the operation of the extracorporeal circulation device 1 to prevent air bubbles from entering the patient P's body.

A pressure sensor is provided in the tube 11 (12, 19) of the circulation circuit of the extracorporeal circulation device 1. The pressure sensor can be attached, for example, to any one or all of the following: attachment position A1 of the blood removal tube 11, attachment position A2 of the blood return tube 12 of the circulation circuit, or attachment position A3 of the connecting 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 using the extracorporeal circulation device 1. Note that 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 at any position in the circulation circuit.

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 the catheter 30. This catheter 30 is used as the venous catheter (blood removal catheter) 5 in Figure 1. Note that the configuration of the catheter 30 described below is one example, and the catheter through which the stylet 50 according to this embodiment is inserted is not limited to the configuration described below.

As shown in Figure 2, the catheter 30 comprises 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 at the proximal end of the tube 31, a catheter connector 35 connecting the tube 31 and the clamping tube 34, and a lock connector 36.

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 (extreme tip) and its surroundings, and the proximal end refers to a certain range including the proximal end (extreme base) and its surroundings.

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

When inserting the catheter 30 into the 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 body in a pre-assembled state.

The following describes each component of the catheter 30. Note that the configuration of the catheter 30 is not limited to the following.

As shown in Figure 2, the tube 31 has an expansion section 32 and a shaft section 33 connected to the base end of the expansion section 32.

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.

The lengths of the extension section 32 and shaft section 33 are configured to be the lengths necessary to position 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 blood removal target. The length of the extension 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.

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.

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

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.

Furthermore, after the catheter 30 has been 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 Figure 7(D)). Here, the expansion section 32 is positioned in the inferior vena cava, a relatively large blood vessel. Therefore, the outer diameter of the expansion section 32 can be increased, and the inner diameter can be increased accordingly.

Here, the pressure loss within 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. In other words, by increasing the inner diameter of the expansion section 32, the pressure loss within the expansion section 32 is reduced. When the pressure loss within 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.

On the other hand, if the wall thickness is approximately constant, increasing the inner diameter of the expansion section 32 and 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.

In light of the above, the inner diameter of the expansion portion 32 can be, for example, 9 to 11 mm, and the inner diameter of the shaft portion 33 can be, for example, 4 to 8 mm. Furthermore, the thickness of the expansion portion 32 and the shaft portion 33 can be, for example, 0.4 to 0.5 mm.

Furthermore, as shown in Figure 2, it is preferable that the tip of the expansion section 32 form a tapered section that gradually narrows from the center of the expansion section 32 toward the tip in the axial direction. This allows the inner diameter of the tip of the expansion section 32 to be continuous with the inner diameter of the tip tip 49 located on the tip side.

As shown in Figure 5(A), the expansion section 32 has a first reinforcing body 321 made of cross-braided wires W, and a first resin layer 322 provided to cover the first reinforcing body 321.

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

The first reinforcing member 321 is constructed by braiding wire W at a braiding angle θ1, as shown in Figure 5(A). The second reinforcing member 331 is constructed by braiding wire W at a braiding angle θ2, as shown in Figure 5(B).

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

As shown in Figures 5(A) and 5(B), the braid angle θ1 of the first reinforcing body 321 is configured to be smaller than the braid angle θ2 of the second reinforcing body 331. Therefore, the inclination angle of the wire W that constitutes the first reinforcing body 321 with respect to the axial direction is smaller than when the braid angle of the first reinforcing body 321 is larger than the braid angle of the second reinforcing body 331. Note that the braid angle θ1 of the first reinforcing body 321 may be configured to be larger than the braid angle θ2 of the second reinforcing body 331.

Here, as the expansion section 32 expands in the axial direction, the wire W constituting the first reinforcement 321 of the expansion section 32 deforms so that its inclination angle relative to the axial direction gradually decreases. Then, when the inclination angle relative to the axial direction of the wire W constituting the first reinforcement 321 of the expansion section 32 becomes approximately zero, the axial expansion of the expansion section 32 is restricted.

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.

The braiding angle θ1 of the first reinforcing member 321 is not particularly limited, but is between 100 and 120 degrees. The braiding angle θ2 of the second reinforcing member 331 is not particularly limited, but is between 130 and 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, the kink resistance of the second reinforcing member 331 can be improved. This allows the catheter 30 to be inserted into the body in an optimal manner, even in the femoral vein, which has a complex structure.

As shown in Figures 5(A) and (B), the first reinforcement 321 of the expansion section 32 is braided more loosely than the second reinforcement 331 of the shaft section 33. This configuration allows the expansion section 32 to be softer than the shaft section 33, thereby improving its flexibility.

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.

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

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

By making the wire diameter of the wire W 0.1 mm or more, it can optimally function as a reinforcing material that improves strength.

On the other hand, by making the wire diameter of the wire W 0.2 mm or less, the outer diameter of the expansion section 32 can be reduced while the inner diameter can be increased, thereby reducing the burden on the patient's body when inserting the catheter 30 and reducing pressure loss. In this embodiment, the cross section of the wire W is circular, but is not limited to this and may be rectangular, square, elliptical, etc.

The first resin layer 322 of the expansion section 32 is made of a softer material with lower hardness than the second resin layer 332 of the shaft section 33. This configuration allows the expansion section 32 to be softer than the shaft section 33, thereby improving its flexibility.

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

Silicone materials are highly biocompatible and, because the material itself is soft, have the advantage of being less likely to damage blood vessels. Polyethylene materials are soft yet hard enough to withstand pressure. Moreover, polyethylene materials have biocompatibility comparable to silicone materials. Polyethylene materials are harder than silicone, making them easier to insert into thin blood vessels. Polyurethane materials also have the advantage of softening after insertion. Materials that take advantage of the advantages of these materials can be used as materials for the first and second resin layers 322, 332.

The polyurethane material may also be coated with a hydrophilic material. In this case, the tube surface is smooth, making it easier to insert into the blood vessel and less likely to damage the blood vessel wall. It is also less likely to attract blood or proteins, which is expected to prevent the formation of blood clots.

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

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.

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 multiple first side holes 63 arranged circumferentially. In this embodiment, the shaft portion 33 is provided with four first side holes 63 arranged circumferentially. As a result, even if one first side hole 63 is blocked by adhesion to the blood vessel wall during blood removal, blood removal can still be performed through the other first side holes 63, ensuring stable blood circulation.

As shown in Figures 2 to 4, the distal tip 49 is positioned at the distal end of the expansion section 32. The distal tip 49 has a tapered shape with a gradually decreasing diameter toward the distal end.

A flat receiving surface 48 is formed on the inside of the distal tip 49 to abut against the flat surface 50a of the stylet 50, which is used prior to inserting the catheter 30 into the body.

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 draining blood. 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.

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

As shown in Figures 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.

As shown in Figures 2 and 4, the catheter connector 35 connects the shaft portion 33 and the clamp tube 34. A lumen through which the stylet 50 can be inserted is provided inside the catheter connector 35.

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

Next, the configuration of the sheath 40 according to this embodiment will be described with reference to Figure 6 and other figures. Figure 6 is a diagram used to explain the configuration of the sheath 40 according to this embodiment.

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.

The outer periphery of the main body portion 41 is configured as a restricting portion 43 that restricts radial contraction of the shaft portion 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 portion 41 greater than the hardness of the shaft portion 33.

An insertion lumen 41L, into which the 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 Figure 6. This configuration improves the ease of inserting the sheath 40 into the catheter 30. Furthermore, with this configuration, when the expansion section 32 of the tube 31 is extended axially by the stylet 50 (see Figure 7(C)), the expansion section 32 deforms to fit the shape of the distal end 41A of the main body 41, preventing the formation of a step.

When the sheath 40 is set in the catheter 30 (see Figure 7(A)), the tip 41A of the main body 41 is positioned inside the expansion section 32. This configuration prevents the expansion section 32 from unintentionally sagging during use in the state shown in Figure 7(A).

Furthermore, with this configuration, the sheath 40 protects the lumen surface of the catheter 30, preventing the lumen surface of the catheter 30 from being damaged by the tip of the stylet 50 when inserting it.

The material constituting the main body 41 is not particularly limited, but can be the same as that used for the first and second resin layers 322 and 332 described above.

As shown in Figure 6, the holding portion 42 is composed of a single component, and includes 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.

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

In addition, a partition 42A is interposed between the first holding portion 44 and the second holding portion 45. This partition 42A prevents the holding force of the second holding portion 45 from being transmitted to the first holding portion 44 when the second holding portion 45 is held, thereby preventing the first holding portion 44 from opening (i.e., releasing the hold on the catheter 30).

The inner cavity of the second holding portion 45 expands in diameter toward the base end in the axial direction. This makes it easier to insert the stylet hub 52 and to grasp the stylet hub 52 together with the second holding portion 45. Furthermore, when removing the stylet 50 from the second holding portion 45, the second holding portion 45 opens in the direction that expands its expanded diameter, making it easy to attach and detach the stylet 50.

The retaining portion 42 is made of, for example, rubber and is elastic. However, the retaining portion 42 is not limited to rubber as long as it has the ability to retain, and can be made of any material that allows a tight fit between the male thread portion 36A of the catheter 30 and the stylet hub 52 of the stylet 50.

Next, returning to Figure 2, the configuration of the stylet 50 according to this embodiment will be described.

As shown in Figure 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.

The stylet tube 51 is a relatively rigid, elongated body that extends axially. The overall axial length of the stylet tube 51 is configured to be approximately the same as the overall axial length of the catheter 30. The stylet tube 51 has 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 the living body together with the sheath 40 and 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.

The stylet tube 51 is relatively rigid and has the stiffness to transmit the pushing force toward the distal end caused by hand manipulation to the tube 31. Therefore, when the stylet tube 51 is pushed toward the distal end while secured to the catheter 30, it serves to dilate narrow blood vessels. Furthermore, it is preferable that the hardness of the stylet tube 51 be less than the hardness of the main body 41 of the sheath 40. With this configuration, as shown in Figure 7, the portion where the stylet tube 51 is exposed from the main body 41 can be made flexible, while the portion where the stylet tube 51 is positioned inside the main body 41 can be made rigid. This improves operability.

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 portion 42. The stylet 50 can be held in the sheath 40 by pushing the tip 52A of the stylet hub 52 into the second holding portion 45.

<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 Fig. 7 omits the wire W, first side hole 63, second side hole 46, and the like of the catheter 30.

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. The male thread portion 36A of the lock connector 36 of the catheter 30 is then engaged 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, preventing the expansion portion 32 from unintentionally sagging. As a result, the risk of the catheter tip coming into contact with the floor or the like and becoming contaminated is reduced.

Next, as shown in Figure 7 (B), the stylet 50 is inserted into the lumen 30A of the catheter 30 with the sheath 40 set in place. 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.

As shown in Figure 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.

Then, as shown in Figure 7(C), the tip of the expansion section 32 is pulled toward the tip. As a result, the catheter 30 is subjected to an axially stretching force, and the expansion section 32, which has relatively high elasticity within the catheter 30, stretches axially. Additionally, the shaft section 33 attempts to contract radially inward, but the restricting section 43 of the sheath 40 prevents the shaft section 33 from contracting radially inward. In this state, by moving the stylet 50 toward the tip, the expansion section 32 stretches axially and appropriately contracts radially inward.

Then, as shown in Figure 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 catheter 30.

Next, the catheter 30, to which the sheath 40 and stylet 50 are fixed, is inserted along a guidewire (not shown) that has been previously inserted into the target area inside the body. 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 body in a minimally invasive manner, minimizing the strain on the patient's body.

The catheter 30 is then 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, first side hole 63, and second side hole 46 positioned in the blood removal target, the expansion section 32 is positioned in the inferior vena cava, a relatively large blood vessel, and the shaft section 33 is positioned in the femoral vein, a relatively small blood vessel.

Next, the sheath 40, stylet 50, and guidewire are removed from the catheter 30. At this time, the holding force of the second holding portion 45 is greater than the holding force of the first holding portion 44. Therefore, 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 their connection.

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 it received 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 fluid flow rate.

Next, connect the lock connector 36 of the catheter 30 to the blood removal tube 11 of the extracorporeal circulation device shown in Figure 1. After confirming that the blood supply catheter connection is complete, release the clamping tube 34 and begin extracorporeal circulation.

Once extracorporeal circulation is complete, the catheter 30 is removed from the blood vessel, and hemostasis is repaired at the insertion site using a surgical procedure, if necessary.

As described above, the sheath 40 according to this embodiment is 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 a 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 detachably attached to the catheter 30, it can be easily removed from the interior of the catheter 30. As a result, it is possible to provide a sheath 40 that can restrict radial contraction of the shaft portion 33 when inserting the stylet 50, and that can be easily removed from inside the catheter 30.

The sheath 40 according to this embodiment also 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.

The first holding portion 44 is an elastic piece that can press the catheter 30 radially inward. This simple configuration allows the sheath 40 to remain inserted into the catheter 30.

The second holding portion 45 is an elastic piece that can press the stylet 50 radially inward. This simple configuration allows the stylet 50 to be maintained inserted into the insertion lumen 41L.

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 connection between the sheath 40 and stylet 50. This improves operability during the procedure.

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. This configuration allows the restricting portion 43 to be configured with a simple structure.

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

<Modified Catheter>
Next, a modified example of the catheter will be described. In the above-described embodiment, the sheath 40 and stylet 50 are applied to a catheter 30 having a single 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 the catheter 60 having double lumens will be described below with reference to Figures 8 and 9.

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

As shown in Figures 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 within the inner cavity of the shaft portion 133.

The catheter 60 enables veno-venous (VV) extracorporeal blood circulation, in which the pump of the extracorporeal circulation device is operated to draw blood from the patient's vein (vena cava), the blood is oxygenated through gas exchange in the oxygenator, and the blood is then returned to the patient's vein (vena cava).

As shown in Figures 8 and 9, the catheter 60 has an expansion section 32, a shaft section 133, a distal tip 49 disposed at the tip of the expansion section 32, and a third tube 161 disposed within 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 will not be described here.

As shown in Figure 9, the catheter 60 has a first lumen 61 that functions as a blood supply channel and a second lumen 62 that functions as a blood removal channel.

The first lumen 61 is formed in the inner cavity of the third tube 161. The second lumen 62 is formed in the inner cavity of the expansion section 32 and the shaft section 133, and extends from the tip to the base end.

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

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

The blood feed side hole 163 and the blood removal side hole 164 are oval in shape.

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

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

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 be positioned at different blood removal targets within the living body to enable efficient blood removal. Furthermore, even if the through hole 47, second side hole 46, or blood removal side hole 164 is blocked by adhesion to the blood vessel wall, blood can still be removed from the unblocked hole, ensuring stable extracorporeal circulation.

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.

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.

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

As shown in FIG. 9, the lock connector 136 has a first lock connector 137 that communicates with the first lumen 61, and a second lock connector 138 that is arranged in parallel to the first lock connector 137 and communicates with the second lumen 62. The lock connector 136 is a Y-shaped connector formed by the first lock connector 137 branching off from the second lock connector 138.

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.

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

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.

For example, in the above-described embodiment, the first retaining portion 44 was an elastic piece that could press the tube 31 radially inward. However, the first retaining portion may also be a female threaded portion that can be threaded onto the male threaded portion 36A of the lock connector 36.

Furthermore, the material that makes up 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; for example, it can be made of a known elastic material.

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

Furthermore, in the above-described embodiment, an example was given of a configuration in which the catheter 30 includes an expansion section 32. However, the catheter may also be configured without an expansion section.

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 of the sheath 140 and secured to the catheter 30 by, for example, threading, thereby securing the sheath 140 to the proximal end of the catheter 30. Engagement of the catheter 30 and the stylet 150 with the holder 141 allows the sheath 140 to be easily removed when the stylet 150 is removed.

30, 60 catheter (percutaneous catheter),
30A lumens,
31 catheter tube (tube),
32 extension part,
33, 133 shaft portion,
36A male thread part,
40, 140 sheath,
41 main body,
41A: tip of the main body;
41L insertion lumen,
43 Regulatory Department,
44 first holding part,
45 second holding part,
50, 150 stylet.

Claims (6)

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 . 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 . The sheath of claim 2 , wherein the second retaining portion has a greater retaining force than the first retaining portion. The sheath according to claim 1 , wherein the restricting portion is configured such that the hardness of the main body portion is greater than the hardness of the shaft portion. 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. The sheath according to any one of claims 1 to 5 ;
the stylet inserted into the insertion lumen of the sheath.