Patent Description:
Conventionally, a catheter assembly used when performing an infusion or the like to a patient has been known. This kind of the catheter assembly includes a hollow catheter, a catheter hub fixed to a proximal end of the catheter, a hollow inner needle which is inserted into the catheter and has a sharp needle tip at a distal end, and a needle hub fixed to a proximal end of the inner needle (for example, see <CIT>). When using a catheter assembly, a skin and a blood vessel of a living body are punctured with each distal end of the inner needle and the catheter, and then, the catheter is advanced with respect to the inner needle so that the catheter is inserted into the blood vessel by a predetermined length.

In a conventional catheter assembly having an inner needle and a catheter, a catheter distal end is sometimes caught by a blood vessel back wall (a blood vessel wall opposing a puncture site) when a puncture angle is large. As a result, the catheter is hardly inserted into a blood vessel or the blood vessel wall is damaged by the catheter distal end.

The present invention has been made in consideration of such problems, and an object thereof is to provide a catheter assembly capable of preventing a catheter distal end from being caught by a blood vessel back wall at the time of advancing a catheter to a blood vessel even when a puncture angle is large.

In order to achieve the above object, the present invention. In particular, the present invention relates to a cathter assembly according to the preamble of claim <NUM>, such as it is e.g. known from <CIT>.

According to the catheter assembly having the above configuration, the flexible portion, which is more flexible than the catheter body, is provided at the distal portion of the catheter body, and thus, it is possible to prevent a distal end of the catheter from being caught by a blood vessel back wall even when a puncture angle is large. As a result, it is possible to prevent the catheter from being hardly inserted into a blood vessel or to prevent a blood vessel wall from being damaged by the catheter distal end.

A flow path for flashback confirmation may be formed between the catheter and the inner needle, the inner needle may be provided with an introduction path which communicates with the flow path to introduce blood into the flow path, and a proximal end of the introduction path may be provided on a proximal side of an axial center position of a portion of the flexible portion present on a distal side of a most distal portion of the catheter body.

With this configuration, it is possible to prevent the catheter from blocking the introduction path at the time of puncture, and thus, it is possible to easily confirm the flashback of blood.

A flow path for flashback confirmation may be formed between the catheter and the inner needle, the inner needle may be provided with an introduction path which communicates with the flow path to introduce blood into the flow path, the catheter may have a close contact portion where at least a part of an inner peripheral surface is in close contact with an outer peripheral surface of the inner needle, and at least a proximal end of the introduction path may be provided on a proximal side of the close contact portion.

The catheter has a close contact portion where at least a part of an inner peripheral surface is in close contact with an outer peripheral surface of the inner needle, and both the flexible portion and the catheter body are in close contact with the inner needle at the close contact portion.

With this configuration, an appropriate fitting force between the inner needle and the catheter can be obtained.

The catheter has a mixed region in which the catheter body and the flexible portion overlap each other in a radial direction.

With this configuration, a change in rigidity from the catheter body to the flexible portion can be made gradual, and thus, it is possible to more favorably prevent the catheter distal end from being caught by the blood vessel back wall at the time of inserting the catheter into the blood vessel.

An axial length of the portion of the flexible portion present on the distal side of the most distal portion of the catheter body is <NUM> to <NUM>.

With this configuration, it is possible to suppress curling of the distal end (flexible portion) of the catheter at the time of puncture. In addition, it is possible to more preferably suppress the catching by the blood vessel back wall at the time of inserting the catheter. Further, it is possible to suppress crushing of the catheter distal end at the time of blood suction.

The catheter may have a mixed region in which the catheter body and the flexible portion overlap each other in a radial direction, and an interface between the catheter body and the flexible portion in the mixed region may be formed in a tapered shape inclined with respect to an axis of the catheter.

With this configuration, the change in rigidity from the catheter body to the flexible portion can be made more gradual.

A boundary between the catheter body and the flexible portion or a boundary between a first flexible portion and a second flexible portion may be coated. The whole catheter may be coated seamlessly.

With this configuration, it is possible to eliminate a step between the catheter body and the flexible portion on an inner peripheral surface and an outer peripheral surface of the catheter. Since the step is eliminated, it is possible to prevent thrombus and to reduce a penetration resistance at the time of puncture.

A creep strain of the catheter body may be greater than a creep strain of the flexible portion.

With this configuration, the catheter body is easily adapted to a shape of the blood vessel after the catheter is inserted into the blood vessel to remain indwelled. Thus, it is possible to reduce a sense of incompatibility given to the patient during indwelling of the catheter. In addition, crushing of the catheter distal end can be reduced.

The interface between the catheter body and the flexible portion may be provided with a region having a different acoustic impedance from the catheter body and the flexible portion.

With this configuration, the above-described region having the different acoustic impedance functions as an echogenic portion, and thus, it is possible to improve the visibility of the distal portion of the catheter under ultrasound fluoroscopy.

At least the flexible portion between the catheter body and the flexible portion may be provided with a deformation suppressing member that suppresses a radial deformation.

With this configuration, it is possible to suppress curling of the catheter distal end (flexible portion) at the time of puncture, and to suppress crushing of the catheter distal end at the time of blood suction.

The inner needle may be provided with a backcut.

A cover may be provided on an outer surface of the flexible portion, and a friction coefficient of a surface of the cover may be set to be smaller than a friction coefficient of a surface of the flexible portion.

A cover may be provided on an outer surface of the flexible portion and an outer surface of the catheter body, a friction coefficient of a surface of the catheter body may be smaller than a friction coefficient of a surface of the flexible portion, and a friction coefficient of a surface of the cover may be smaller than the friction coefficient of the surface of the catheter body.

At least a part of the flexible portion may be in close contact with the inner needle.

According to the catheter assembly of the present invention, it is possible to prevent the catheter distal end from being caught by the blood vessel back wall at the time of advancing the catheter to the blood vessel even when the puncture angle is large.

The flexible portion may have a flexible tapered portion which is inclined with respect to the axis of the catheter such that an outer diameter decreases in a distal direction, the flexible tapered portion may have a first flexible tapered portion including the most distal portion and a second flexible tapered portion provided to be adjacent to a proximal side of the first flexible tapered portion, and an inclination angle of an outer peripheral surface of the first flexible tapered portion with respect to the axis may be larger than that of the second flexible tapered portion.

With this configuration, the first flexible tapered portion is relatively thick, and thus, it is possible to suppress the curling of the catheter distal end at the time of puncture. The second flexible tapered portion has the relatively small inclination angle, and thus, the penetration resistance can be reduced.

The catheter body may have a body tapered portion which is inclined with respect to the axis of the catheter such that an outer diameter decreases in the distal direction and is arranged on a radially inner side of the flexible tapered portion, the body tapered portion may have a first body tapered portion and a second body tapered portion provided to be adjacent to a proximal side of the first body tapered portion, and an inclination angle of an outer peripheral surface of the first body tapered portion with respect to the axis may be larger than that of the second body tapered portion.

With this configuration, the inclination angle of the first body tapered portion is relatively large, and thus, it is possible to support the flexible portion from the inner side at the time of blood suction and to suppress a collapse of the flexible portion. Since the inclination angle of the second body tapered portion is relatively small, the gradual transition from a physical property of the flexible portion to a physical property of the catheter body becomes possible, and a kink of the catheter can be suppressed.

The inclination angle of the first body tapered portion may be smaller than the inclination angle of the first flexible tapered portion.

An inner peripheral surface of the flexible tapered portion and an inner peripheral surface of the first body tapered portion may be in close contact with the outer peripheral surface of an inner needle.

A flow path for flashback confirmation may be formed between the catheter and the inner needle, the inner needle may be provided with a side hole which communicates with the flow path and to introduce blood into the flow path, and the side hole may be provided on a proximal side of a most distal portion of the body tapered portion.

With this configuration, the side hole is provided at a position opposing the relatively hard catheter body. Therefore, it is possible to prevent the catheter from blocking the side hole at the time of puncture, and thus, it is possible to easily confirm the flashback of blood.

The distal portion of the catheter may have a close contact portion in close contact with an outer peripheral surface of the inner needle, the outer peripheral surface of the inner needle may be provided with an ultrasound reflection promoting portion having an uneven shape, and a distal portion of the ultrasound reflection promoting portion may be provided on a proximal side of a proximal portion of the close contact portion.

With this configuration, the close contact portion and the ultrasound reflection promoting portion do not overlap each other so that the uneven shape of the ultrasound reflection promoting portion does not contribute to a resistance at the time of removing the inner needle, and the removal operation is stabilized.

The flexible portion may have a color that is more easily visible than the catheter body, and the catheter body may have transparency that allows an inside of the catheter body to be visible.

Since the flexible portion is colored to be easily noticeable while securing the flashback visibility by giving the transparency to the catheter body, it is easy to perform puncture with respect to a target blood vessel. In addition, it is easy to understand that the flexible portion is provided at the distal portion of the catheter, and thus, it is possible to appeal to a user that a function of preventing a blood vessel injury is high.

The flexible portion may have a higher X-ray contrast property than the catheter body.

It is possible to enhance the contrast property by X-rays at the time of breaking the catheter while securing the flashback visibility by setting the flexible portion to have the higher X-ray contrast property than the catheter body.

A deflection suppressing mechanism that is capable of supporting the catheter at the time of puncture and suppresses deflections of the inner needle and the catheter may be provided, and the deflection suppressing mechanism may be arranged on a proximal side of the flexible portion in an initial state of the catheter assembly.

With this configuration, it is possible to prevent the deflection suppressing mechanism from damaging the flexible portion at the time of advancing the catheter with respect to the inner needle.

Hereinafter, preferred embodiments of a catheter assembly according to the present invention will be described with reference to the accompanying drawings.

The catheter assembly <NUM> whose initial state is illustrated in <FIG> is applied when performing an infusion, a blood transfusion, and the like to a patient (living body), and constructs an introduction portion of a medicinal liquid or the like by being tapped into the patient's body to remain indwelled. The catheter assembly <NUM> may be configured as a catheter (for example, a central venous catheter, a PICC, a mid-line catheter, and the like) having a longer length than a peripheral venous catheter. Incidentally, the catheter assembly <NUM> may be configured as the peripheral venous catheter. In addition, the catheter assembly <NUM> is not limited to the venous catheter, and may be configured as an arterial catheter such as a peripheral arterial catheter.

As illustrated in <FIG>, the catheter assembly <NUM> includes a catheter <NUM>, a catheter hub <NUM> fixedly holding the catheter <NUM>, a hollow inner needle <NUM> removably inserted into the catheter <NUM>, a needle hub <NUM> fixedly holding the inner needle <NUM>, and a catheter operation member <NUM> mounted to the catheter hub <NUM>. The inner needle <NUM> may be a solid needle.

The catheter assembly <NUM> forms a multi-tube structure (multi-tube portion) in which the catheter <NUM> and the inner needle <NUM> are sequentially stacked in an initial state before use.

The catheter <NUM> has flexibility and in which a lumen <NUM> is formed to penetrate therethrough. The lumen <NUM> is formed to have a diameter capable of housing the inner needle <NUM> and capable of causing a medicinal liquid, blood, or the like to flow. A distal end of the catheter <NUM> is reduced in diameter in order to decrease a puncture resistance, and an inner surface of the catheter <NUM> is in close contact with an outer surface of the inner needle <NUM> at such a reduced diameter portion in the initial state of the catheter assembly <NUM>. A length of the catheter <NUM> is not particularly limited but can be appropriately designed according to use and various conditions, and is set to, for example, about <NUM> to <NUM>, about <NUM> to <NUM>, or about <NUM> to <NUM>.

A proximal portion of the catheter <NUM> is fixed to a distal portion inside the catheter hub <NUM>. The catheter <NUM> and the catheter hub <NUM> form a catheter member <NUM>.

The catheter hub <NUM> is exposed on the patient's skin in a state where the catheter <NUM> has been inserted into a blood vessel, and indwelled together with the catheter <NUM> by being pasted with a tape or the like. The catheter hub <NUM> is formed in a tubular shape tapered in a distal direction.

A constituent material of the catheter hub <NUM> is not particularly limited, but a thermoplastic resin, such as polypropylene, polycarbonate, polyamide, polysulfone, polyarylate, a methacrylate-butylene-styrene copolymer, and polyurethane may be preferably applied.

A hollow portion <NUM> which communicates with the lumen <NUM> of the catheter <NUM> and through which an infusion solution can flow is provided inside the catheter hub <NUM>. A hemostatic valve, a plug, or the like (not illustrated) may be housed inside the hollow portion <NUM> in order to prevent back-flow of blood at the time of puncture with the inner needle <NUM> and to allow infusion along with insertion of a connector of an infusion tube.

The inner needle <NUM> is configured as a hollow tube having rigidity that enables puncture of a skin of a living body, and is arranged to penetrate through the lumen <NUM> of the catheter <NUM> and the hollow portion <NUM> of the catheter hub <NUM>. The inner needle <NUM> is formed to have a total length longer than that of the catheter <NUM>, and a sharp needle tip 16a is provided at a distal end thereof. A lumen penetrating in an axial direction of the inner needle <NUM> is provided inside the inner needle <NUM>, and this lumen communicates with a distal opening of the inner needle <NUM>.

Examples of a constituent material of the inner needle <NUM> include a metal material such as stainless steel, aluminum or an aluminum alloy, and titanium or a titanium alloy, a hard resin, ceramics, and the like.

The needle hub <NUM> has a needle holding member <NUM> fixed to a proximal portion of the inner needle <NUM>, and a housing <NUM> to which the needle holding member <NUM> is fixed and which extends along the inner needle <NUM> and the catheter <NUM>. The catheter assembly <NUM> houses a part of the multi-tube portion, the catheter hub <NUM>, and the catheter operation member <NUM> in the housing <NUM> in the initial state. Resin materials forming the needle holding member <NUM> and the housing <NUM> are not particularly limited, but, for example, the materials exemplified for the catheter hub <NUM> can be appropriately selected. Incidentally, the needle holding member <NUM> and the housing <NUM> may be integrally formed.

When the needle hub <NUM> is moved to a proximal direction with respect to the catheter <NUM>, the inner needle <NUM> is also moved in the proximal direction with respect to the catheter <NUM> along with the movement of the needle hub <NUM> since the needle hub <NUM> holds the inner needle <NUM> at the needle holding member <NUM>.

The catheter operation member <NUM> is attached to the catheter hub <NUM>. Thus, when the catheter operation member <NUM> is advanced relative to the needle hub <NUM>, the catheter member <NUM> is advanced relative to the inner needle <NUM>. The catheter operation member <NUM> has a hub mounting portion 20a detachably mounted on the catheter hub <NUM>, and an operation plate portion 20b extending from the hub mounting portion 20a along the catheter <NUM> in the distal direction. Incidentally, the catheter operation member <NUM> is not necessarily provided in the catheter assembly <NUM>.

The catheter assembly <NUM> is provided with a support member <NUM> on the distal side of the housing <NUM> in order to support a lower side of the catheter <NUM> held by the catheter operation member <NUM>. The support member <NUM> is rotatably attached to an arrangement recess portion 24a provided at a distal portion of the housing <NUM>. A distal portion of the catheter operation member <NUM> and the support member <NUM> constitute a deflection suppressing mechanism <NUM>.

When the skin is punctured with the inner needle <NUM> and the catheter <NUM>, the distal portion of the catheter operation member <NUM> supports the catheter <NUM> from above and the support member <NUM> supports the catheter <NUM> from below, and thus, deflections of the catheter <NUM> and the inner needle <NUM> are suppressed. When the catheter operation member <NUM> is removed out of the housing <NUM>, the support member <NUM> is rotated toward an outer side of the housing <NUM> by being pushed by the hub mounting portion 20a, and thus, the catheter hub <NUM> can be withdrawn from the housing <NUM> in the distal direction. Incidentally, the support member <NUM> is not necessarily provided.

As illustrated to <FIG>, the catheter <NUM> has a close contact portion <NUM>, which is in close contact with an outer peripheral surface of the inner needle <NUM>, in at least a part of an inner peripheral surface. The close contact portion <NUM> is provided on the inner peripheral surface of a distal portion of the catheter <NUM>. A flow path for flashback confirmation (hereinafter, referred to as "flashback flow path <NUM>") is formed between the catheter <NUM> and the inner needle <NUM> on the proximal side of the close contact portion <NUM>. The flashback flow path <NUM> extends up to a proximal opening of the catheter <NUM>.

The catheter <NUM> has a catheter body <NUM> that constitutes a main portion of the catheter <NUM> and a flexible portion <NUM> provided at a distal portion of the catheter body <NUM>. Thus, the catheter <NUM> becomes more flexible toward the most distal portion on the distal side. The flexible portion <NUM> is exposed from the housing <NUM> (<FIG>).

The catheter body <NUM> accounts for most of the whole length of the catheter <NUM>. Thus, the most distal portion of the catheter body <NUM> is positioned near the most distal end of the catheter <NUM>. The catheter <NUM> and the flexible portion <NUM> are made of a resin material having flexibility. A creep strain of the catheter body <NUM> is greater than a creep strain of the flexible portion <NUM>.

The catheter body <NUM> has: a straight portion 34a which has a constant outer diameter along the axial direction; a tapered portion 34b which extends from the straight portion 34a in the distal direction and has an outer diameter decreasing in the distal direction; and a distal constituting portion 34c which extends from the tapered portion 34b in the distal direction and constitutes a portion up to the most distal portion of the catheter body <NUM>. An inner peripheral surface of the distal constituting portion 34c and the outer peripheral surface of the inner needle <NUM> are in close contact with (fitted to) each other in a liquid-tight manner over the entire peripheral.

The flashback flow path <NUM> is formed between an inner peripheral surface of the catheter body <NUM> (specifically, the straight portion 34a and the tapered portion 34b) and the outer peripheral surface of the inner needle <NUM>. At least the catheter body <NUM> between the catheter body <NUM> and the flexible portion <NUM> has transparency such that a flashback can be confirmed.

The catheter <NUM> is supported by the support member <NUM> (<FIG>) at a spot of the catheter body <NUM> (the catheter body <NUM> is supported by the support member <NUM>). As a result, it is possible to reliably support the catheter <NUM> and to reduce a sliding resistance at the time of advancing the catheter <NUM>. Moreover, the portion supported by the support member <NUM> (<FIG>) is located on the proximal side of an interface <NUM> between the catheter body <NUM> and the flexible portion <NUM>, and thus, it is possible to prevent peeling of the interface <NUM> caused by sliding of the catheter <NUM> with respect to the support member <NUM>.

It is preferably that the catheter body <NUM> be less likely to swell as compared to the flexible portion <NUM>. As a result, it is possible to set an axial distance between a most distal position of the inner needle <NUM> and a most distal position of the catheter <NUM> to a desired size and to reduce a variation for each product during steam sterilization (autoclave sterilization) or ethylene oxide gas sterilization in a process of manufacturing the catheter assembly <NUM>.

Examples of a constituent material of the catheter body <NUM> include a fluorine-based resin such as polytetrafluoroethylene (PTFE), an ethylene-tetrafluoroethylene copolymer (ETFE), and a perfluoroalkoxy fluorine resin (PFA), an olefin-based resin such as polyethylene and polypropylene or a mixture thereof, polyurethane, polyester, polyamide, a polyether nylon resin, a mixture of the olefin-based resin and an ethylene-vinyl acetate copolymer, and the like. The hardness (Shore A) of the catheter body <NUM> is, for example, less than <NUM> D.

The flexible portion <NUM> includes the most distal portion of the catheter <NUM>. The flexible portion <NUM> is more flexible than the catheter body <NUM>. That is, an elastic modulus k1 of the catheter body <NUM> and an elastic modulus k2 of the flexible portion <NUM> have a relationship of k1 > k2.

The flexible portion <NUM> has: a straight portion 38a which has a constant outer diameter along the axial direction; and a tapered portion 38b which extends from the straight portion 38a in the distal direction and has an outer diameter decreasing in the distal direction. An inner peripheral surface of the flexible portion <NUM> and the outer peripheral surface of the inner needle <NUM> are in close contact with (fitted to) each other in a liquid-tight manner over the entire peripheral.

It is preferable that at least the flexible portion <NUM> between the catheter body <NUM> and the flexible portion <NUM> have an X-ray contrast property. As a result, for example, when the catheter <NUM> is broken in a blood vessel, it is possible to easily confirm a location of the catheter <NUM>, which has been broken and left in the blood vessel, by X-ray. A contrast layer in the case where the flexible portion <NUM> has the contrast property may be provided, for example, in any form of a stripe shape, an intermediate layer in the radial direction, or the whole layer.

Examples of a constituent material of the flexible portion <NUM> include various rubber materials such as natural rubber, butyl rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, silicone rubber, various thermoplastic elastomers such as polyurethanes, polyesters, polyamides, olefins, and styrenes or a mixture thereof, and the like.

In the catheter <NUM>, a single catheter body region 40A where only the catheter body <NUM> between the catheter body <NUM> and the flexible portion <NUM> exists, a single flexible portion region 40B where only the flexible portion <NUM> between the catheter body <NUM> and the flexible portion <NUM> exists, and a mixed region 40C where the catheter body <NUM> and the flexible portion <NUM> exist are arranged in the axial direction. In the catheter <NUM> illustrated in <FIG>, the interface <NUM> between the catheter body <NUM> and the flexible portion <NUM> is formed in a tapered shape which is inclined at a substantially constant angle with respect to an axis of the catheter <NUM>.

The single catheter body region 40A is a portion of the catheter body <NUM> present on the proximal side of a most proximal portion of the flexible portion <NUM>.

The single flexible portion region 40B is a portion of the flexible portion <NUM> present on the distal side of the most distal portion of the catheter body <NUM>. An axial length L1 of the single flexible portion region 40B is set to, according to the invention, <NUM> to <NUM>, preferably <NUM> to <NUM>, and more preferably <NUM> to <NUM>. The hardness of the flexible portion <NUM> (the single flexible portion region 40B) is, for example, <NUM> D to <NUM> D and preferably <NUM> D to <NUM> D at <NUM>. The flexible portion <NUM> in the illustrated example is joined to the catheter body <NUM>. Since the axial length and the hardness of the single flexible portion region 40B are set within the above ranges, it is possible to prevent the distal end (the flexible portion <NUM>) of the catheter <NUM> from being curled at the time of puncture. In addition, it is possible to preferably suppress catching by a blood vessel back wall at the time of inserting the catheter <NUM>. Further, it is possible to suppress crushing of the distal end of the catheter <NUM> at the time of blood suction.

The mixed region 40C is a portion in which the catheter body <NUM> and the flexible portion <NUM> are stacked in the radial direction. An axial length L2 of the mixed region 40C is set to, for example, <NUM> to <NUM>, and preferably <NUM> to <NUM>.

In the catheter <NUM> illustrated in <FIG>, the interface <NUM> between the catheter body <NUM> and the flexible portion <NUM> is inclined in the distal direction so as to approach the axis (center) of the catheter <NUM>. Thus, the flexible portion <NUM> is present on the outer side of the catheter body <NUM> in the mixed region 40C.

The catheter assembly <NUM> may be provided with a needle protection member that covers the needle tip 16a when the inner needle <NUM> is removed from the catheter <NUM>. In this case, a protrusion (not illustrated) is provided on the outer peripheral surface of the inner needle <NUM> to prevent the needle protection member from being removed from the inner needle <NUM> in the distal direction, and the protrusion is preferably provided on the proximal side of the single flexible portion region 40B. As a result, the interface <NUM> between the catheter body <NUM> and the flexible portion <NUM> is not caught by the protrusion at the time of advancing the catheter <NUM>, and it is possible to prevent peeling of the interface <NUM> caused by the protrusion.

The catheter <NUM> is preferably coated seamlessly with a single coating material on the whole catheter <NUM> in order to eliminate (or minimize) a step at a boundary between the catheter body <NUM> and the flexible portion <NUM> on the inner peripheral surface and an outer peripheral surface of the catheter body <NUM>.

Instead of the above configuration having the interface <NUM>, the catheter <NUM> may be formed so as to become soft in the distal direction by changing each compounding amount of materials different in hardness in the axial direction. In this case, extrusion molding may be performed while changing each extrusion speed of different materials. Alternatively, a content of a plasticizer at the distal portion of the catheter may be increased. In this case, the plasticizer may be applied to the distal portion of the catheter.

In the inner needle <NUM>, a backcut portion 16c, which is continuous with the needle tip 16a and is inclined in a reverse direction to the blade face 16b with respect to the axis of the inner needle <NUM>, is provided on the opposite side to a blade face 16b. In order to suppress piercing of the inner surface of the catheter <NUM> by the needle tip 16a when the catheter <NUM> is retracted after advancing the catheter <NUM> once with respect to the inner needle <NUM>, a radial length Lb from the needle tip 16a to the backcut portion 16c at a position of <NUM> from the needle tip 16a in the proximal direction is set to, for example, <NUM> to <NUM>, and more preferably, set to <NUM> to <NUM>. It is sufficient if the needle tip 16a is offset to the radially inner side in order to obtain the same effect, and the needle tip 16a may be curved instead of the backcut.

As illustrated in <FIG>, among projection lines P forming a contour shape of a projection image when the distal portion of the inner needle <NUM> is projected from just beside, at least a part of a projection line Pa, which corresponds to a portion (the backcut portion 16c in the present embodiment) of the distal portion of the inner needle <NUM> formed on the opposite side of the blade face 16b and continuous with the needle tip 16a, preferably passes between a straight line C1 at <NUM>° with respect to a straight line Lp, which passes through the needle tip 16a and is perpendicular to a longitudinal direction of the inner needle <NUM>, and a straight line C2 at <NUM>° with respect to the straight line Lp. More preferably, at least a part of the projection line Pa passes between a straight line C3 at <NUM>° with respect to the straight line Lp and a straight line C4 at <NUM>° with respect to the straight line Lp. In <FIG>, the projection line Pa is a straight line, the whole projection line Pa passes between the straight line C1 and the straight line C2.

With this configuration, it is possible to achieve both the prevention of the piercing of the inner surface of the catheter <NUM> by the needle tip 16a and penetration properties with respect to the skin. When at least a part of the projection line Pa is present in a region closer to the straight line Lp than the straight line C1, the above-described piercing hardly occurs, but the penetration resistance becomes large. When at least a part of the projection line Pa is present in a region where an angle with the straight line Lp is larger than an angle with the straight line C4, the penetration resistance is low, but the above-described piercing is likely to occur.

The backcut portion 16c may be formed in a curved shape that bulges toward the straight line Lp like a projection line Pa1. At least a part of the projection line Pa1 preferably passes between the straight line C1 and the straight line C2, and more preferably passes between the straight line C3 and the straight line C4. The backcut portion 16c may be formed in a shape curved in an S shape like a projection line Pa2. At least a part of the projection line Pa2 preferably passes between the straight line C1 and the straight line C2, and more preferably passes between the straight line C3 and the straight line C4.

The inner needle <NUM> is provided with an introduction path <NUM> which communicates with the flashback flow path <NUM> to introduce blood into the flashback flow path <NUM>. The introduction path <NUM> illustrated in <FIG> is a side hole 44A which penetrates through a wall portion of the inner needle <NUM> in the radial direction. As illustrated in <FIG>, the introduction path <NUM> may be a groove portion 44B extending in the axial direction on the outer peripheral surface of the inner needle <NUM>.

In the initial state of the catheter assembly <NUM> illustrated in <FIG> and <FIG>, a proximal end 44a of the introduction path <NUM> is provided on the proximal side of an axial center position Pc of the single flexible portion region 40B. More specifically, at least the proximal end 44a of the introduction path <NUM> is provided on the proximal side of a most distal portion of the single catheter body region 40A. The whole side hole 44A illustrated in <FIG> is provided on the proximal side of the most distal portion of the single catheter body region 40A. Incidentally, a part of the side hole 44A may be present on the distal side of the most distal portion of the single catheter body region 40A.

In <FIG>, the whole side hole 44A is provided on the proximal side of the mixed region 40C. A part of the side hole 44A may be present on the distal side of a proximal end of the mixed region 40C.

Regarding a position of the introduction path <NUM> in relation to the close contact portion <NUM>, at least the proximal end 44a of the introduction path <NUM> (the side hole 44A or the groove portion 44B) is provided on the proximal side of the close contact portion <NUM> in the initial state of the catheter assembly <NUM> illustrated in <FIG> and <FIG>. The whole side hole 44A illustrated in <FIG> is provided on the proximal side of the close contact portion <NUM>.

As illustrated in <FIG>, which illustrates an example not falling under the invention as claimed, only the inner peripheral surface of the flexible portion <NUM> between the catheter body <NUM> and the flexible portion <NUM> may be in close contact with the outer peripheral surface of the inner needle <NUM> (the catheter body <NUM> is not necessarily close contact with the outer peripheral surface of the inner needle <NUM>). In addition, in this case, the whole side hole 44A may be provided on the distal side of the most distal portion (a most distal portion of the interface <NUM>) of the single catheter body region 40A as illustrated in <FIG>. That is, the side hole 44A may be provided on the inner side of the flexible portion <NUM>. The side hole 44A may have a proximal end positioned on the proximal side of the most distal portion of the single catheter body region 40A and a distal end positioned at the same axial position as the most distal portion or on the distal side of the most distal portion of the single catheter body region 40A.

Next, functions of the catheter assembly <NUM> configured as described above will be described.

In use of the catheter assembly <NUM> illustrated in <FIG>, a puncturing operation to puncture the patient's skin with the catheter assembly <NUM> is performed. In the puncturing operation, a user (a doctor, a nurse, or the like) presses the distal portion of the catheter assembly <NUM> against the patient while gripping the housing <NUM>, thereby puncturing the skin toward a puncture target blood vessel. Accordingly, the skin is punctured with the inner needle <NUM> and each distal portion of the catheter <NUM>.

Next, the user operates the catheter operation member <NUM> in the distal direction to cause the catheter member <NUM> (the catheter <NUM> and the catheter hub <NUM>) to advance while fixing the position of the needle hub <NUM> (the housing <NUM>). Accordingly, the catheter <NUM> is inserted to the target position in the blood vessel.

Next, the user pulls the housing <NUM> in the proximal direction while holding the positions of the catheter operation member <NUM> and the catheter member <NUM>. Accordingly, the catheter member <NUM> and the catheter operation member <NUM> completely come out of the housing <NUM>, and the inner needle <NUM> is removed from the catheter <NUM> in the proximal direction.

Next, the catheter operation member <NUM> is detached from the catheter hub <NUM>. Accordingly, the catheter member <NUM> is indwelled in the patient. Incidentally, the catheter operation member <NUM> may be kept attached to the catheter hub <NUM> depending on a preference of the user.

Next, the connector of the infusion tube (not illustrated) is connected to the proximal side (the proximal portion of the catheter hub <NUM>) of the catheter member <NUM> from which the inner needle <NUM> has been removed, and the infusion solution (medicinal liquid) is administered from the infusion tube to the patient.

In this case, the catheter assembly <NUM> according to the present embodiment has the following effects.

According to the catheter assembly <NUM>, the flexible portion <NUM>, which is more flexible than the catheter body <NUM>, is provided at the distal portion of the catheter body <NUM> as illustrated in <FIG>. Thus, it is possible to prevent the distal end of the catheter <NUM> from being caught by a blood vessel back wall 50a, which is a blood vessel wall of a blood vessel <NUM> on the opposite side of a puncture spot at the time of advancing the catheter <NUM> to insert the catheter <NUM> into the blood vessel <NUM> after puncturing a skin S with the distal portion of the catheter assembly <NUM> even when a puncture angle is large as illustrated in <FIG>.

That is, the flexible portion <NUM> is brought into contact with the blood vessel back wall 50a and is pressed by the blood vessel back wall 50a to be easily deformed at the time of advancing the catheter <NUM> as illustrated in <FIG>, and thus, it is possible to prevent the distal end of catheter <NUM> from being caught by the blood vessel back wall 50a. As a result, it is possible to prevent the catheter <NUM> from being hardly inserted into the blood vessel <NUM> or to prevent the blood vessel back wall 50a from being damaged by the distal end of the catheter <NUM>.

As illustrated in <FIG>, the flashback flow path <NUM> is formed between the catheter <NUM> and the inner needle <NUM>, and the inner needle <NUM> is provided with the introduction path <NUM> which communicates with the flashback flow path <NUM> to introduce blood into the flashback flow path <NUM>. The proximal end 44a of the introduction path <NUM> is provided on the proximal side of the axial center position Pc of the portion of the flexible portion <NUM> present on the distal side of the most distal portion of the catheter body <NUM>. In addition, the catheter <NUM> has the close contact portion <NUM> in which at least a part of the inner peripheral surface is in close contact with the outer peripheral surface of the inner needle <NUM>, and at least the proximal end of the introduction path <NUM> is provided on the proximal side of the close contact portion <NUM>.

With the above configuration, it is possible to prevent the flexible portion <NUM> from being deformed to block the introduction path <NUM> at the time of puncture, and thus, it is possible to easily confirm the flashback of blood.

In the close contact portion <NUM>, both the flexible portion <NUM> and the catheter body <NUM> are in close contact with the inner needle <NUM>. With this configuration, an appropriate fitting force between the inner needle <NUM> and the catheter <NUM> can be obtained. With the appropriate fitting force, the flexible portion <NUM> is prevented from being curled, and the inner needle <NUM> can be easily removed from the catheter <NUM> at the time of puncturing the skin.

The catheter <NUM> has the mixed region 40C in which the catheter body <NUM> and the flexible portion <NUM> overlap each other in the radial direction. With this configuration, a change in rigidity from the catheter body <NUM> to the flexible portion <NUM> can be made gradual, and thus, it is possible to more favorably prevent the distal end of the catheter <NUM> from being caught by the blood vessel back wall 50a at the time of inserting the catheter <NUM> into the blood vessel <NUM>.

The axial length of the single flexible portion region 40B (the portion of the flexible portion <NUM> present on the distal side of the most distal portion of the catheter body <NUM>) is <NUM> to <NUM>. With this configuration, it is possible to suppress the curling of the distal end (the flexible portion <NUM>) of the catheter <NUM> at the time of puncture. In addition, it is possible to more preferably suppress the catching by the blood vessel back wall 50a at the time of inserting the catheter <NUM>. Further, it is possible to suppress crushing of the distal end of the catheter <NUM> at the time of blood suction.

The interface <NUM> between the catheter body <NUM> and the flexible portion <NUM> in the mixed region 40C is formed in the tapered shape which is inclined with respect to the axis of the catheter <NUM>. With this configuration, the change in rigidity from the catheter body <NUM> to the flexible portion <NUM> can be made more gradual.

The whole catheter <NUM> is coated seamlessly. With this configuration, it is possible to eliminate the step between the catheter body <NUM> and the flexible portion <NUM> on the inner peripheral surface and the outer peripheral surface of the catheter <NUM>. Since the step is eliminated, it is possible to prevent thrombus and to reduce a penetration resistance at the time of puncture.

A creep strain of the catheter body <NUM> is greater than a creep strain of the flexible portion <NUM>. With this configuration, the catheter body <NUM> is easily adopted to a shape of the blood vessel after the catheter <NUM> is inserted into the blood vessel <NUM> to remain indwelled. Thus, it is possible to reduce a sense of incompatibility given to the patient during indwelling of the catheter <NUM>. In addition, the flexible portion <NUM> has the smaller creep strain than the catheter body <NUM>, and thus, can easily return to the original shape even if being deformed. Thus, it is possible to reduce the crushing of the distal end of the catheter <NUM> caused by the blood suction.

As illustrated in <FIG>, the interface <NUM> between the catheter body <NUM> and the flexible portion <NUM> may be inclined at a substantially constant angle so as to be separated farther from the axis of the catheter <NUM> in the distal direction. Even with this configuration, the change in rigidity from the catheter body <NUM> to the flexible portion <NUM> can be made gradual similarly to the case in which the interface <NUM> is inclined at the substantially constant angle so as to approach the axis of the catheter <NUM> in the distal direction (<FIG>).

As illustrated in <FIG>, the interface <NUM> may have a plurality of regions aligned in the axial direction, and regions adjacent to each other among the plurality of regions may have different angles with respect to the axis of the catheter <NUM>. With this configuration, it becomes easy to adjust the rigidity in the mixed region 40C in which the catheter body <NUM> and the flexible portion <NUM> overlap each other in the radial direction, and thus, the change in rigidity from the catheter body <NUM> to the flexible portion <NUM> can be easily adjusted.

In <FIG>, the interface <NUM> is inclined so as to approach the axis of the catheter <NUM> in the distal direction. Specifically, the interface <NUM> has: a first region 42a; a second region 42b which is adjacent to the distal side of the first region 42a and is inclined with respect to the first region 42a; and a third region 42c which is adjacent to the distal side of the second region 42b and is inclined with respect to the second region 42b. An angle of the second region 42b with respect to the axis of the catheter <NUM> is smaller than angles of the first region 42a and the third region 42c with respect to the axis of the catheter <NUM>. The angles of the first region 42a and the third region 42c with respect to the axis of the catheter <NUM> may be the same or different from each other.

As illustrated in <FIG>, the interface <NUM> may be inclined so as to be separated farther from the axis of the catheter <NUM> in the distal direction and may have a plurality of regions aligned in the axial direction. Even with this configuration, it becomes easy to adjust the rigidity in the mixed region 40C in which the catheter body <NUM> and the flexible portion <NUM> overlap each other in the radial direction similarly to the configuration of <FIG>, and thus, the change in rigidity from the catheter body <NUM> to the flexible portion <NUM> can be easily adjusted.

In <FIG>, the interface <NUM> has: a first region 42d; a second region 42e which is adjacent to the distal side of the first region 42d and is inclined with respect to the first region 42d; and a third region 42f which is adjacent to the distal side of the second region 42e and is inclined with respect to the second region 42e. An angle of the second region 42e with respect to the axis of the catheter <NUM> is smaller than angles of the first region 42d and the third region 42f with respect to the axis of the catheter <NUM>. The angles of the first region 42d and the third region 42f with respect to the axis of the catheter <NUM> may be the same as or different from each other.

As in <FIG>, according to an alternative not falling under the invention as claimed, the interface <NUM> between the catheter body <NUM> and the flexible portion <NUM> may be perpendicular to the axis of the catheter <NUM>.

The catheter assembly <NUM> may employ a catheter 12a illustrated in <FIG> or a catheter 12b illustrated in <FIG>. In the catheters 12a and 12b illustrated in <FIG>, deformation suppressing members <NUM> and <NUM>, respectively, suppressing a radial deformation are provided in at least the flexible portion <NUM> between the catheter body <NUM> and the flexible portion <NUM>. With this configuration, it is possible to suppress curling of the distal end (the flexible portion <NUM>) of the catheter 12a or 12b at the time of puncture, and to suppress crushing of the distal end of the catheter 12a or 12b at the time of blood suction. The deformation suppressing member <NUM> or <NUM> has a shape that makes at least one turn in a circumferential direction. With this configuration, the radial deformation can be more effectively suppressed.

The catheter 12a illustrated in <FIG> is provided with a plurality of the deformation suppressing members <NUM>. Specifically, the deformation suppressing members <NUM> are provided on the inner peripheral surface, the outer peripheral surface, the inside, and the distal end of the catheter body <NUM> in the mixed region 40C, and on the inner peripheral surface and the outer peripheral surface of the flexible portion <NUM>, but may be provided at any one spot or a plurality of spots among these sites. The deformation suppressing member <NUM> provided in the flexible portion <NUM> is preferably a member harder than the catheter body <NUM> (a member having a higher elastic modulus). Incidentally, the deformation suppressing member <NUM> provided in the flexible portion <NUM> may be a member that has the same hardness as the catheter body <NUM> or is softer than the catheter body <NUM>.

The deformation suppressing member <NUM> provided in the flexible portion <NUM> is preferably a member having a smaller creep strain than the catheter body <NUM>. Incidentally, the deformation suppressing member <NUM> provided in the flexible portion <NUM> is preferably a member having a smaller creep strain than the flexible portion <NUM>. When the deformation suppressing member <NUM> having the small creep strain is provided, the distal end of the catheter 12a is easily restored to the original shape at the time of stopping suction even if blood is suctioned at an excessive speed so that the distal end of the catheter 12a is crushed.

In the catheter 12b illustrated in <FIG>, the deformation suppressing member <NUM> continuously extending from the single flexible portion region 40B over the mixed region 40C is provided concentrically with the catheter 12b. Specifically, the deformation suppressing member <NUM> is provided inside the flexible portion <NUM>. The deformation suppressing member <NUM> may be provided on the outer peripheral surface of the flexible portion <NUM>. The deformation suppressing member <NUM> is preferably a member harder than the catheter body <NUM> (a member having a higher elastic modulus). Incidentally, the deformation suppressing member <NUM> may be a member that has the same hardness as the catheter body <NUM> or is softer than the catheter body <NUM>.

The deformation suppressing member <NUM> (or the deformation suppressing member <NUM>) can adopt various forms as illustrated in <FIG>. Deformation suppressing members 54a to <NUM> in cells A to G have tube-like (ring-like) forms. Specifically, the deformation suppressing member 54a in the cell A has a straight shape with a constant outer diameter in the axial direction. The deformation suppressing member 54b in the cell B has a tapered shape with an outer diameter changing in the axial direction. The deformation suppressing member 54c in the cell C has a straight shape with a constant outer diameter in the axial direction, and has a large number of through-holes <NUM> penetrating in the radial direction.

The deformation suppressing member 54d in the cell D has a large number of recess portions <NUM> on an outer peripheral surface (or an inner peripheral surface). The deformation suppressing member 54e in the cell E has a ring-shaped groove <NUM> on an outer peripheral surface (or an inner peripheral surface). The deformation suppressing member 54f in the cell F has a cavity <NUM> inside a circumferential wall. The deformation suppressing member <NUM> in the cell G is configured using a porous body (for example, a sintered body).

Deformation suppressing members <NUM> to 54j in cells H to J have coil-like forms. Specifically, the deformation suppressing member <NUM> in the cell H has a straight shape with a constant outer diameter in the axial direction. The deformation suppressing member 54i in the cell I has a tapered shape with an outer diameter changing in the axial direction. The deformation suppressing member 54j in the cell J is configured in multiple spirals.

Deformation suppressing members 54o and 54p in a cell O and a cell P have tubular net-like forms. Specifically, the deformation suppressing member 54o in the cell O has a straight shape with a constant outer diameter in the axial direction. The deformation suppressing member 54p in the cell P has a tapered shape with an outer diameter changing in the axial direction.

As wires constituting the deformation suppressing members <NUM> to 54j, 54o, and 54p in the cell H to the cell J, the cell O, and the cell P, a wire <NUM> having a circular cross section as in the cell K may be used, wires 68a to 68c having non-circular cross sections as in cells La to Lc (an elliptical shape in a cell La, a rectangular shape in a cell Lb, and a star shape in a cell Lc) may be used, a hollow wire <NUM> as in a cell M may be used, or a twisted wire <NUM> as in a cell N may be used.

Next, an example of a method of manufacturing the catheter <NUM> provided with the deformation suppressing member <NUM> will be described. As illustrated in <FIG>, the deformation suppressing member <NUM> is fitted (mounted) to a core member <NUM>. Next, a first tube member <NUM>, which is a material of the catheter body <NUM>, is mounted to the core member <NUM>, and the other deformation suppressing member <NUM> is fitted to an outer peripheral surface of a distal portion of the first tube member <NUM> as illustrated in <FIG>. Next, an object is molded by pressing and heating the first tube member <NUM> and the deformation suppressing members <NUM> with a mold (not illustrated). As a result, the catheter body <NUM> formed in a tapered shape with a tapered distal portion as illustrated in <FIG> is obtained.

Next, the deformation suppressing member <NUM> is fitted to the core member <NUM> on the distal side of the catheter body <NUM> as in <FIG>. Next, a second tube member <NUM>, which is a material of the flexible portion <NUM> and has the other deformation suppressing members <NUM> mounted on an inner peripheral surface and an outer peripheral surface thereof, is mounted to the core member <NUM> and the distal portion of the catheter body <NUM> as illustrated in <FIG>. Then, the second tube member <NUM> and the deformation suppressing member <NUM> are pressed and heated using a mold (not illustrated) (which may be the same as the mold used at the time of molding the distal portion of the first tube member <NUM>). As a result, the flexible portion <NUM> formed in a tapered shape with a tapered distal portion as illustrated in <FIG> is obtained.

Next, the deformation suppressing member <NUM> is fitted on the outer peripheral surface of the flexible portion <NUM> as illustrated in <FIG>. Then, the deformation suppressing member <NUM> is pressed and heated using a mold (not illustrated) (which may be the same as the mold used at the time of molding the distal portion of the first tube member <NUM> or the second tube member <NUM>) so that the deformation suppressing member <NUM> is embedded in the outer peripheral surface of the flexible portion <NUM> as illustrated in <FIG>. As a result, the catheter 12a provided with the deformation suppressing members <NUM> is obtained.

Incidentally, installation spots and the number of the deformation suppressing members <NUM> can be changed as appropriate in the above method of manufacturing the catheter <NUM>.

As illustrated in <FIG>, it is also possible to manufacture the second tube member <NUM> provided with the deformation suppressing member <NUM> (or the deformation suppressing member <NUM>) by performing blade processing or multi-layer molding at the time of manufacturing the second tube member <NUM>, which is the material of the flexible portion <NUM>.

The second tube member <NUM> illustrated in <FIG> is obtained by forming the deformation suppressing member <NUM> (see deformation suppressing members 54o and 54p in <FIG>) having a form of a blade (a tubular net-like member) as an intermediate layer. The second tube member <NUM> illustrated to <FIG> is obtained by forming the deformation suppressing member <NUM> as an inner layer by multi-layer molding. The second tube member <NUM> illustrated to <FIG> is obtained by forming the deformation suppressing member <NUM> as an outer layer by multi-layer molding. The second tube member <NUM> illustrated to <FIG> is obtained by forming the deformation suppressing member <NUM> as an intermediate layer by multi-layer molding.

In a catheter 12c illustrated in <FIG>, the interface <NUM> between the catheter body <NUM> and the flexible portion <NUM> is provided with a region <NUM> having a different acoustic impedance from the catheter body <NUM> and the flexible portion <NUM>. With this configuration, the above-described region <NUM> having the different acoustic impedance functions as an echogenic portion, and thus, it is possible to improve the visibility of the distal portion of the catheter <NUM> under ultrasound fluoroscopy. Hereinafter, the region <NUM> having the different acoustic impedances is referred to as an "echogenic portion 80a".

The echogenic portion 80a is provided on the proximal side of the portion of the flexible portion <NUM> present on the distal side of the most distal portion of the catheter body <NUM>. With this configuration, it is possible to prevent peeling at the interface <NUM> between the catheter body <NUM> and the flexible portion <NUM> when the catheter 12c is advanced with respect to the inner needle <NUM>.

A shape of the echogenic portion 80a may have the same shape as the deformation suppressing member <NUM>. The shape of the echogenic portion 80a may be granular. A material of the echogenic portion 80a may be the same as or different from that of the deformation suppressing member <NUM>. The echogenic portion 80a is not necessarily rigid, and thus, may be air, gel, or the like.

When a granular body is used as the echogenic portion 80a, a glass bead is particularly preferable. When a test was performed by providing the glass bead as the echogenic portion 80a, favorable visibility was obtained with the glass bead having a diameter of <NUM> to <NUM>.

The first tube member <NUM>, which is the material of the catheter body <NUM>, or the second tube member <NUM>, which is the material of the flexible portion <NUM>, (or both) may be molded by extrusion molding while mixing the granular body which is to form the echogenic portion 80a therein.

In a catheter 12d illustrated in <FIG>, the flexible portion <NUM> has a first flexible portion 38A which is more flexible than the catheter body <NUM>, and a second flexible portion 38B which is provided to be adjacent to the distal side of the first flexible portion 38A and is more flexible than the first flexible portion 38A. That is, an elastic modulus k2a of the first flexible portion 38A, an elastic modulus k2b of the second flexible portion 38B, and the elastic modulus k1 of the catheter body <NUM> have a relationship of k1 > k2a > k2b.

With this configuration, the change in rigidity from the catheter body <NUM> to the flexible portion <NUM> can be made more gradual. Thus, it is possible to more favorably prevent the distal end of the catheter 12d from being caught by the blood vessel back wall 50a at the time of inserting the catheter 12d into the blood vessel <NUM>, and to prevent the peeling of the interface <NUM> at the joint between the catheter body <NUM> and the flexible portion <NUM>.

In the catheter 12e illustrated in <FIG>, the flexible portion <NUM> has a first flexible portion 38C which is more flexible than the catheter body <NUM>, and a second flexible portion 38D which is provided on the distal side of the first flexible portion 38C, includes a most distal portion of the catheter 12e, and is harder than the first flexible portion 38C. That is, an elastic modulus k2c of the first flexible portion 38C, an elastic modulus k2d of the second flexible portion 38D, and the elastic modulus k1 of the catheter body <NUM> have a relationship of k1 > k2d > k2c. With this configuration, it is possible to suppress the crushing of the flexible portion <NUM> at the time of blood suction.

In a catheter 12f of a catheter assembly 10a illustrated in <FIG>, a cover <NUM> is provided on an outer surface of the flexible portion <NUM> and an outer surface of the catheter body <NUM> such that a friction coefficient of an outer surface of the catheter 12f decreases. The cover <NUM> covers the whole outer surface of the catheter 12f. A friction coefficient T1 of the surface of the flexible portion <NUM>, a friction coefficient T2 of the surface of the catheter body <NUM>, and a friction coefficient T3 of the surface of the cover <NUM> have a relationship of T3 < T2 < T1. Examples of a material forming the cover <NUM> include silicone, methoxyethyl (meth) acrylate, and the like.

According to the catheter assembly 10a, the cover <NUM> is provided on the outer surface of the flexible portion <NUM>, and the friction coefficient T3 of the surface of the cover <NUM> is smaller than the friction coefficient T1 of the surface of the flexible portion <NUM>. Since the cover <NUM> having a small friction coefficient is provided on the outer surface of the flexible portion <NUM> in this manner, it is possible to suppress the curling of the soft flexible portion <NUM> at the time of puncturing the skin so that the cover <NUM> easily passes a skin puncture hole. In addition, at least a part of the flexible portion <NUM> is in close contact with the inner needle <NUM>, and thus, the flexible portion <NUM> is less likely to be displaced from the inner needle <NUM> at the time of puncturing the skin and can be prevented from being curled.

According to the catheter assembly 10a, the cover <NUM> is provided on the outer surface of the flexible portion <NUM> and the outer surface of the catheter body <NUM>, the friction coefficient T2 of the surface of the catheter body <NUM> is smaller than the friction coefficient T1 of the surface of the flexible portion <NUM>, and the friction coefficient T3 of the surface of the cover <NUM> is smaller than the friction coefficient T2 of the surface of the catheter body <NUM>. Thus, it is possible to suppress the curling of the soft flexible portion <NUM> at the time of puncturing the skin so that the cover <NUM> easily passes a skin puncture hole. In addition, since the friction coefficient T2 of the surface of the catheter body <NUM> is set to be small, it is possible to suppress an increase of a frictional force between the catheter 12f and the inner needle <NUM>, and thus, an advancing operation is easily performed at the time of advancing the catheter 12f relative to the inner needle <NUM>. Further, a difference between the friction coefficient T2 of the surface of the catheter body <NUM> and the friction coefficient T1 of the surface of the flexible portion <NUM> is not too large, and thus, the flexible portion <NUM> can be prevented from being curled inward at the time of advancing the catheter 12f relative to the inner needle <NUM>.

In an inner needle 16A of a catheter assembly 10b illustrated in <FIG>, a friction-increased shape portion <NUM> having at least one of a recess portion (groove) and a convex portion (protrusion) that increases a friction coefficient of an outer peripheral surface of the inner needle 16A is provided on the outer peripheral surface of the inner needle 16A. With this configuration, the friction coefficient of the outer peripheral surface of the inner needle 16A is increased, and thus, it is possible to prevent the catheter <NUM> from being curled at the time of puncturing the skin with the catheter <NUM>. The friction-increased shape portion <NUM> is provided at a position opposing an inner peripheral surface of the distal portion of the catheter <NUM>.

In <FIG>, the friction-increased shape portion <NUM> is a groove structure <NUM>. More specifically, the groove structure <NUM> is a spiral groove 87a. Instead of the spiral groove 87a, a plurality of annular grooves may be provided at intervals in the axial direction.

When the friction-increased shape portion <NUM> is formed using the groove structure <NUM>, the groove structure <NUM> is more preferably provided at a position overlapping the flexible portion <NUM> in the axial direction. When a human body is punctured with the catheter assembly 10b and the catheter <NUM> passes a skin puncture hole, a radial force from the outer surface of the catheter <NUM> to a central axis of the catheter <NUM> is applied so that the flexible portion <NUM> is deformed and the flexible portion <NUM> bites into the inside (recess portion) of the groove structure <NUM>. Since a force, which causes the flexible portion <NUM> biting into the recess portion (the spiral groove 87a or the annular groove) of the groove structure <NUM> and holds the position of the flexible portion <NUM>, overcomes a force generated as the flexible portion <NUM> is displaced from the inner needle 16A and deformed, it is possible to further prevent the catheter <NUM> from being curled at the time of puncture.

The friction-increased shape portion <NUM> is not limited to the groove structure <NUM> but may be a protrusion structure. The protrusion structure may be a spiral protrusion, or may be a plurality of annular protrusions formed at intervals in the axial direction. The friction-increased shape portion <NUM> may be a roughened portion that has been subjected to processing to increase surface roughness. In this case, the roughened portion is a structure having a large number of fine recess shapes (grooves) and convex shapes (protrusions) that increase the friction coefficient of the outer peripheral surface of the inner needle 16A. When the roughened portion is provided, a position of the inner needle 16A can be confirmed by ultrasound irradiation at the time of puncturing the human body with the catheter assembly 10b.

The above-described groove structure <NUM> or protrusion structure may be configured to form a gap with respect to the inner peripheral surface of the catheter <NUM>. As a result, ultrasound reflection of the ultrasound from an ultrasound imaging apparatus at a boundary of the gap is promoted, and a position of the groove structure <NUM> or the protrusion structure of the inner needle 16A can be recognized more favorably on a monitor of the ultrasound imaging apparatus.

The friction-increased shape portion <NUM> provided on the outer peripheral surface of the inner needle 16A is not necessarily provided at the position opposing the most distal portion of the flexible portion <NUM>. As a result, the distal end of the flexible portion <NUM> is less likely to be curled at the time of puncture.

A catheter <NUM> of a catheter assembly 10c illustrated in <FIG> has the catheter body <NUM> and the flexible portion <NUM> provided at the distal portion of the catheter body <NUM>. The inner peripheral surface of the catheter body <NUM> and the inner peripheral surface of the flexible portion <NUM> are in close contact with an outer peripheral surface of an inner needle 16B over the whole circumference. A portion, which is in close contact with the outer peripheral surface of the inner needle 16B, at the distal portion of the catheter <NUM> constitutes a close contact portion <NUM>.

The catheter body <NUM> has: a body tapered portion 34t which is inclined with respect to an axis of the catheter <NUM> such that an outer diameter decreases in the distal direction; and a flexible tapered portion 38t which is inclined with respect to the axis of the catheter <NUM> such that the outer diameter decreases in the distal direction.

The body tapered portion 34t is arranged on the radially inner side of the flexible tapered portion 38t. The body tapered portion 34t has a first body tapered portion 34t1 and a second body tapered portion 34t2 provided to be adjacent to the proximal side of the first body tapered portion 34t1. The flexible tapered portion 38t has a first flexible tapered portion 38t1 including a most distal portion of the catheter <NUM>, and a second flexible tapered portion 38t2 provided to be adjacent to the proximal side of the first flexible tapered portion 38t1.

The first body tapered portion 34t1 has an inclination angle at an outer peripheral surface with respect to the axis of the catheter <NUM> larger than that of the second body tapered portion 34t2. According to this configuration, the inclination angle of the first body tapered portion 34t1 is relatively large, and thus, it is possible to support the flexible portion <NUM> from the inner side at the time of blood suction and to suppress a collapse of the flexible portion <NUM>. Since the inclination angle of the second body tapered portion 34t2 is relatively small, the gradual transition from a physical property of the flexible portion <NUM> to a physical property of the catheter body <NUM> becomes possible, and a kink of the catheter <NUM> can be suppressed.

The first flexible tapered portion 38t1 has an inclination angle at an outer peripheral surface with respect to the axis of the catheter <NUM> larger than that of the second flexible tapered portion 38t2. According to this configuration, the first flexible tapered portion 38t1 is relatively thick, and thus, it is possible to suppress the curling of the distal end of the catheter <NUM> at the time of puncture. The second flexible tapered portion 38t2 has the relatively small inclination angle, and thus, the penetration resistance can be reduced.

The inclination angle of the first body tapered portion 34t1 is slightly smaller than the inclination angle of the first flexible tapered portion 38t1. The first body tapered portion 34t1 is arranged on the radially inner side of the second flexible tapered portion 38t2. A most proximal portion of the second flexible tapered portion 38t2 is positioned on the proximal side of a most proximal portion of the first body tapered portion 34t1. The flexible portion <NUM> has a straight portion <NUM>, which is parallel to the axis of the catheter <NUM>, on the proximal side of the second flexible tapered portion 38t2.

The flow path <NUM> for flashback confirmation is formed between the catheter <NUM> and the inner needle 16B. The inner needle 16B is provided with a side hole <NUM> which communicates with the flow path <NUM> to introduce blood into the flow path <NUM>. The side hole <NUM> (specifically, a most distal portion of the side hole <NUM>) is provided on the proximal side of a most distal portion of the body tapered portion 34t (the most distal portion of the catheter body <NUM>). With this configuration, the side hole <NUM> is provided at a position opposing the relatively hard catheter body <NUM>. Therefore, it is possible to prevent the catheter <NUM> from blocking the side hole <NUM> at the time of puncture, and thus, it is possible to easily confirm the flashback of blood. The side hole <NUM> is provided on the proximal side of the second body tapered portion 34t2.

An inner peripheral surface of the flexible tapered portion 38t and an inner peripheral surface of the first body tapered portion 34t1 are in close contact with the outer peripheral surface of the inner needle 16B. That is, the close contact portion <NUM> is constituted by the inner peripheral surface of the flexible tapered portion 38t and the inner peripheral surface of the first body tapered portion 34t1.

An ultrasound reflection promoting portion <NUM> having an uneven shape (step shape) is provided on the outer peripheral surface of the inner needle 16B. In <FIG>, the ultrasound reflection promoting portion <NUM> is a spiral groove <NUM> which is recessed with respect to the outer peripheral surface of the inner needle 16B. The ultrasound reflection promoting portion <NUM> may be a spiral protrusion protruding to the radially outer side from the outer peripheral surface of the inner needle 16B. The ultrasound reflection promoting portion <NUM> may be configured using a plurality of ring-shaped grooves or a plurality of ring-shaped protrusions arranged at intervals in the axial direction.

A most distal portion 92a of the ultrasound reflection promoting portion <NUM> is positioned on the distal side of the side hole <NUM>. The most distal portion 92a of the ultrasound reflection promoting portion <NUM> is positioned on the distal side of the most proximal portion of the second flexible tapered portion 38t2. The most distal portion 92a of the ultrasound reflection promoting portion <NUM> is positioned on the distal side of a most proximal portion of the second body tapered portion 34t2.

The most distal portion 92a of the ultrasound reflection promoting portion <NUM> is provided on the proximal side of a proximal portion of the close contact portion <NUM>. According to this configuration, the close contact portion <NUM> and the ultrasound reflection promoting portion <NUM> do not overlap each other so that the uneven shape of the ultrasound reflection promoting portion <NUM> does not contribute to a resistance at the time of removing the inner needle 16B, and the removal operation is stabilized.

A most proximal portion 92b of the ultrasound reflection promoting portion <NUM> is positioned on the proximal side of the side hole <NUM>. The most proximal portion 92b of the ultrasound reflection promoting portion <NUM> is positioned on the proximal side of the most proximal portion of the second flexible tapered portion 38t2. The most proximal portion 92b of the ultrasound reflection promoting portion <NUM> is positioned on the distal side of the most proximal portion of the second body tapered portion 34t2.

In the catheter <NUM>, the catheter body <NUM> has transparency that allows the inside of the catheter body <NUM> to be visible. The flexible portion <NUM> may have a color that is more easily visible than the catheter body <NUM>. When configured in this manner, the flexible portion <NUM> is colored to be easily noticeable while securing the flashback visibility by giving the transparency to the catheter body <NUM>, it is easy to perform puncture with respect to a target blood vessel. In addition, it is easy to understand that the flexible portion <NUM> is provided at the distal portion of the catheter <NUM>, and thus, it is possible to appeal to the user that a function of preventing a blood vessel injury is high.

It is preferable that at least the flexible portion <NUM> between the catheter body <NUM> and the flexible portion <NUM> have an X-ray contrast property. If both the catheter body <NUM> and the flexible portion <NUM> have X-ray contrast properties, the flexible portion <NUM> preferably has a higher X-ray contrast property than the catheter body <NUM>. A contrast layer in the case where the flexible portion <NUM> has the contrast property may be provided, for example, in any form of a stripe shape, an intermediate layer in the radial direction, or the whole layer. When the stripe-shaped contrast layer is provided in the flexible portion <NUM>, the flexible portion <NUM> can have the higher X-ray contrast property than the catheter body <NUM> by making the number of stripes thereof larger than that in a stripe-shaped contrast layer provided in the catheter body <NUM>.

A double needle (Sample <NUM> to <NUM>) consisting of a catheter (<NUM> to <NUM>) and an inner needle (<NUM>) respectively obtained by applying the configurations of the catheter <NUM> and the inner needle 16B in the above-described catheter assembly <NUM> was prepared, and a curling test, a suction test, a penetration resistance test, and a stuck test to be described below were performed. Test results are shown in <FIG>.

Samples <NUM> to <NUM> had flexible portions (soft tips) at distal portions, respectively, and Sample <NUM> had no flexible portion at its tip. In Samples <NUM> to <NUM>, a catheter body was made of relatively hard urethane, and the flexible portion was made of relatively soft urethane. In Sample <NUM>, the catheter was made of only the same hard urethane as the catheter body.

In Samples <NUM> to <NUM>, a "first taper angle" is an inclination angle of a first flexible tapered portion of the flexible portion, and a "second taper angle" is an angle of a second flexible tapered portion of the flexible portion. Sample <NUM> has no flexible portion, but has a first tapered portion corresponding to the first flexible tapered portion, and a "first taper angle" in a table is an inclination angle of the first tapered portion. Similarly, a "second taper angle" in Sample <NUM> in the table is an angle of the second tapered portion corresponding to the second flexible tapered portion. Samples <NUM> to <NUM> have different second taper angles. Samples <NUM> to <NUM> have different distal end tip lengths (distances from most distal portions of the catheter bodies to most distal portions of the flexible portions).

In the curling test, a pig skin and cowhide were used as objects to be punctured, and the object to be punctured was punctured with a sample. The pig skin was used assuming a human skin with standard hardness. The pig skin was punctured at a puncture angle of <NUM>°, and then, its appearance was visually observed. The cowhide was used assuming a stiff human skin. The cowhide was punctured at a puncture angle of <NUM>°, and then, its appearance was visually observed. It was determined as "OK" when the catheter was insertable into the object to be punctured, and it was determined as "NG" when the distal end of the catheter was curled on a surface of the object to be punctured and was not insertable. In the curling test, it is considered that it is disadvantageous if the distal end tip length is long, but the curling does not depend on the second taper angle.

In the suction test, a <NUM> syringe was connected to a catheter hub via an extension tube, and viscosity-adjusted simulated blood at <NUM> was suctioned at a rate of <NUM>/sec to confirm presence or absence of crushing of a catheter. It was determined as "OK" when the crushing did not occur, and it was determined as "NG" when the crushing occurred. In the suction test, it is considered that it is disadvantageous if the distal end tip length is long, and it is disadvantageous if the second taper angle is small.

A polyethylene sheet having a thickness of <NUM> was punctured with each sample at <NUM>/min, and a resistance value (N) applied to each sample was measured by an indentation load tester (Autograph AG-<NUM> kNX manufactured by Shimadzu Corporation). It is considered that the penetration resistance depends on an appearance shape (since the resistance is maximized at a most distal end). In addition, it is considered that the penetration resistance also depends on the first taper angle.

In the stuck test, the following Tests (<NUM>) and (<NUM>) were performed.

From a state where a distal end of a double needle was brought close to a silicone sheet having a thickness of <NUM> (obtained assuming a blood vessel back wall) (a distance from a sheet to a needle tip of an inner needle was <NUM>), and only the catheter was advanced to abut on the sheet to confirm whether a distal portion of the catheter could push the catheter forward by changing its direction on a surface of the sheet. It was recognized as a non-insertable state when the catheter abutted on the sheet so that it was not allowed to push the catheter further forward. A puncture angle was increased at <NUM>-degree intervals, and the maximum angle at which the insertion was possible was recorded.

The puncture angle was fixed at <NUM>°, which is a clinically approximating condition (to actual puncture), a canine blood vessel (inferior vena cava) was punctured with a sample (only Sample <NUM> and <NUM>) in the same manner as in Test (<NUM>) to confirm whether a catheter could be pushed forward to be inserted into the blood vessel. Since one that was insertable in Test (<NUM>) (Sample <NUM>) was inserted up to <NUM>° in Test (<NUM>), those having the penetration angles of <NUM>° or larger in Test (<NUM>) were determined as "OK". Since one that was non-insertable in Test (<NUM>) (Sample <NUM>) was inserted up to <NUM>° in Test (<NUM>), those having the penetration angles of <NUM>° or smaller in Test (<NUM>) were determined as "NG".

In the stuck test, it is considered that it is advantageous if the distal end tip length is long, and it is advantageous if the second taper angle is small.

Based on the test results shown in <FIG>, only Sample <NUM> showed favorable results in all the tests. A desired range of the distal end tip length is longer than <NUM> and shorter than <NUM>. In terms of an outer diameter (<NUM> to <NUM>) of the catheter used for the test, a distal end tip length/catheter outer diameter of the present embodiment is desirably longer than <NUM> and shorter than <NUM>.

In a catheter assembly 10d illustrated in <FIG>, a catheter <NUM> has the catheter body <NUM> and the flexible portion <NUM> provided at a distal portion of the catheter body <NUM>. A ratio of a total length Lc of the catheter body <NUM> to a length Ls of the flexible portion <NUM> is <NUM> to <NUM>. Therefore, when the total length Lc of the catheter body <NUM> is, for example, <NUM>, the length Ls of the flexible portion <NUM> is <NUM>.

As illustrated in <FIG>, the catheter assembly 10d includes the deflection suppressing mechanism <NUM> that is capable of supporting the catheter <NUM> at the time of puncture and suppressing deflections of the inner needle <NUM> and the catheter <NUM>. This deflection suppressing mechanism <NUM> has the same configuration as the deflection suppressing mechanism <NUM> in the above-described catheter assembly <NUM> (see <FIG>), and is constituted by the support member <NUM> provided at the distal portion of the housing <NUM> and the catheter operation member <NUM> mounted on the catheter hub <NUM>.

The deflection suppressing mechanism <NUM> is arranged on the proximal side of the flexible portion <NUM> (the most proximal portion of the flexible portion <NUM>) in an initial state (a state before the catheter <NUM> is advanced with respect to the inner needle <NUM>) of the catheter assembly 10d illustrated in <FIG>. With this configuration, it is possible to prevent the deflection suppressing mechanism <NUM> from damaging the flexible portion <NUM> at the time of advancing the catheter <NUM> with respect to the inner needle <NUM>.

The deflection suppressing mechanism <NUM> is preferably arranged on the proximal side of the flexible portion <NUM> in the vicinity of the flexible portion <NUM> in the initial state of the catheter assembly 10d. As a result, the deflection suppressing mechanism <NUM> can support the catheter <NUM> at a position on the distal side as much as possible within a range not touching the flexible portion <NUM>, and thus, can appropriately exhibit the function of suppressing the deflections of the inner needle <NUM> and the catheter <NUM> while preventing the flexible portion <NUM> from being damaged.

The deflection suppressing mechanism <NUM> may be configured by only any one of the support member <NUM> and the catheter operation member <NUM>. The deflection suppressing mechanism <NUM> may be configured so as to surround the whole circumference of the catheter <NUM>.

Claim 1:
A catheter assembly (<NUM>, 10a - 10d) comprising:
a catheter (<NUM>, 12a - <NUM>); and
wherein the catheter (<NUM>, 12a - <NUM>) has:
a catheter body (<NUM>); and
a flexible portion (<NUM>) which is provided at a distal portion of the catheter body (<NUM>), includes a most distal portion of the catheter (<NUM>, 12a - <NUM>), and is more flexible than the catheter body (<NUM>),
wherein the catheter (<NUM>, 12a - <NUM>) has a mixed region (40C) in which the catheter body (<NUM>) and the flexible portion (<NUM>) overlap each other in a radial direction, and
wherein
in the catheter there are arranged in the axial direction:
a single catheter body region (40A), where only the catheter body (<NUM>) between the catheter body (<NUM>) and the flexible portion (<NUM>) exists,
a single flexible portion region (40B), where only the flexible portion (<NUM>) between the catheter body (<NUM>) and the flexible portion (<NUM>) exists, and
a mixed region (40C), where the catheter body (<NUM>) and the flexible portion (<NUM>) exist;
characterized in that
an inner needle (<NUM>, 16A, 16B) is provided which is inserted through the catheter (<NUM>, 12a - <NUM>),
the catheter (<NUM>, 12a - <NUM>) has a close contact portion (<NUM>, <NUM>) where at least a part of an inner peripheral surface is in close contact with an outer peripheral surface of the inner needle (<NUM>, 16A, 16B),
both the flexible portion (<NUM>) and the catheter body (<NUM>) are in close contact with the inner needle (<NUM>, 16A, 16B) in the close contact portion (<NUM>, <NUM>),
the inner needle and the catheter are configured to be together directly punctured into skin of an individual, and
an axial length of the portion of the flexible portion (<NUM>) present on the distal side of the most distal portion of the catheter body (<NUM>) is <NUM> to <NUM>.