Patent Description:
In the field of hemodialysis, blood is removed from a blood vessel of a patient and purified outside his/her body, and, thereafter, the purified blood is returned to the blood vessel. In such a case, a multi-lumen catheter is used, which includes at least two lumens, i.e., a blood removal lumen for removing blood from a blood vessel of the patient and a blood return lumen for returning the purified blood into the blood vessel of the patient. Documents <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT> disclose a multi-lumen catheter.

Examples of a method for inserting such a catheter into a blood vessel include a method using an introducer sheath, a method using the Seldinger technique, and the like. In the former method, a catheter is inserted into an introducer sheath which has been inserted into a blood vessel in advance, and the catheter is inserted into the blood vessel along a lumen of the introducer sheath until the catheter reaches a target position. In the latter method, a wire inserted in a blood vessel in advance is inserted in a lumen of the catheter, and the catheter is inserted into the blood vessel along the wire until the catheter reaches a target position.

Some of such lumens of the introducer sheaths include a check valve, so that the catheter insertion into such a lumen of the introducer sheath requires the catheter to be passed through the check valve. Moreover, in the Seldinger technique, in which the catheter is inserted into the blood vessel directly, there is particularly a demand for a catheter with an excellent insertability.

In order to meet such requirements and demands, some conventional catheters are configured as follows: Opening positions of a blood removal lumen and a blood return lumen are disposed at different positions in a longitudinal direction (see Patent Document <NUM>, for example).

The catheter of Patent Document <NUM> can have a smaller cross-sectional area at the opening position of the blood return lumen at the distal end of the catheter, thereby improving the insertability of a distal end portion of the catheter. On the other hand, there is no change in the cross-sectional area at the opening position of the blood removal lumen, which results in a problem in that insertion resistance of the catheter suddenly increases at this position, so that overall insertability is hardly improved.

It is an object of the present disclosure to realize a multi-lumen catheter with an excellent insertability.

Further aspects are provided in dependent claims <NUM>-<NUM>.

An aspect of a catheter according to the present disclosure includes: a body that is formed into a cylindrical shape and extends from a proximal end to a distal end and surrounded by an outer wall, an inner space of the body being divided with a partition extending in a longitudinal direction, into a plurality of lumens including a first lumen and a second lumen, the second lumen having a second opening plane at a distal end thereof, and the first lumen having a first opening plane at a distal end thereof, the second opening plane being positioned more distally than the first opening plane, the outer wall including a first outer wall portion defining the first lumen and a second outer wall portion defining the second lumen, the first outer wall portion having a first lumen slit notching a portion of a distal end of the first outer wall portion, the body including a flexible portion having a lower hardness than other portions of the body, and the flexible portion including a distal end portion of the first outer wall portion, the distal end portion including the first lumen slit.

With this configuration, at the catheter insertion, the distal end portion, including the first lumen slit, of the first outer wall portion is deformed to bend into the inner cavity of the first lumen. With this configuration, at the insertion, the cross-sectional area of the body becomes smaller respectively at the first opening plane. Accordingly, the insertion resistance will not increase suddenly, thereby attaining an excellent insertability of the catheter. The distal end portion of the first outer wall portion returns to its original shape after the catheter is indwelled in the blood vessel. This enables to disperse the suction pressure in removing the blood via the first lumen, thereby making it difficult for the sticking to the blood vessel wall to occur.

According to a preferable aspect of the multi-lumen catheter, the first lumen slit may be provided in a circumferential middle portion of the first outer wall portion. This configuration enables to prevent rigidity reduction of the distal end portion of the first outer wall portion while preventing clogging or narrowing of the first opening plane that would be caused by pressing from the blood vessel wall or the like.

According to a preferable aspect of the multi-lumen catheter, the flexible portion may range from the position of a proximal end of the first lumen slit to the distal end of the body. This configuration allows the catheter to be more easily deformable in such a way that the first outer wall portion bends into the inner cavity of the first lumen, thereby attaining a more gradual change in insertion resistance, which allows for further improvement of the insertability of the catheter. Moreover, this configuration allows the catheter to be less damaging to the blood vessel at the insertion.

According to a preferable aspect of the multi-lumen catheter, the first outer wall portion may have at least one first lumen side pore positioned more proximally than the first lumen slit. This configuration enables to disperse the suction pressure in removing the blood via the first lumen, thereby making it difficult for the sticking to the blood vessel wall to occur. Moreover, this configuration enables to easily ensure the amount of blood removed.

According to a preferable aspect of the multi-lumen catheter, the second outer wall portion may have a second lumen slit notching a portion of a distal end of the second outer wall portion, and the flexible portion may include a distal end portion of the second outer wall portion, the distal end portion including the second lumen slit. This configuration enables to make the distal end portion, including the second lumen slit, of the second outer wall portion, deformable to bend into the inner cavity of the second lumen. With this configuration, at the insertion, the cross-sectional area of the body becomes smaller respectively at the second opening plane, thereby further improving the insertability of the catheter. Moreover, the distal end portion of the second outer wall portion returns to its original shape after the catheter is indwelled in the blood vessel, so that the suction pressure can be dispersed in removing the blood via the second lumen, thereby making it difficult for the sticking to the blood vessel wall to occur.

According to a preferable aspect of the multi-lumen catheter, the second outer wall portion may have at least one second lumen side pore. This configuration enables to disperse the suction pressure in removing the blood via the second lumen, thereby making it difficult for the sticking to the blood vessel wall to occur. Moreover, this configuration enables to easily ensure the amount of blood removed.

According to a preferable aspect of the multi-lumen catheter, the first opening plane may be inclined toward the proximal end with respect to the partition, and the second opening plane may be orthogonal to the partition. This configuration enables to obtain a more gradual change in insertion resistance at the first opening plane, thereby further improving the insertability of the catheter. Moreover, this configuration allows for suction pressure reduction at the first opening plane and easily ensures the amount of blood removed.

According to a preferable aspect of the multi-lumen catheter, the plurality of lumens includes three or more lumens. This configuration allows the drug solution administration and the central venous pressure measurement to become performable concurrently with the hemodialysis, thereby reducing the burden on an operator and the patient.

According to a preferable aspect of the multi-lumen catheter, the proximal end of the body is provided with branch pipes being connected respectively to the plurality of lumens and each having a connector at its proximal end. Such a configuration allows hemodialysis to be performed by connecting between the body and a blood circuit and the like via the connectors.

According to the multi-lumen catheter of the present disclosure, in which the first outer wall portion has the first lumen slit and the flexible portion includes the distal end portion of the first outer wall portion, the distal end portion including the first lumen slit, thereby attaining an excellent insertability of the catheter.

A multi-lumen catheter (which will be referred to just as "catheter" hereinafter) of the present disclosure is for use in hemodialysis, in which blood removed via a blood removal lumen of the catheter indwelled in a blood vessel is purified outside the patient's body and the blood thus purified is returned into the blood vessel via a blood return lumen of the catheter.

As illustrated in <FIG>, the catheter of this embodiment includes: a body (a catheter tube) <NUM> that is formed into a cylindrical shape and surrounded by an outer wall <NUM> extending from a proximal end to a distal end. The body <NUM> includes in its inner space a partition <NUM> extending in a longitudinal direction. The partition <NUM> divides the inner space of the body <NUM> into a first lumen <NUM> and a second lumen <NUM>. The outer wall <NUM> includes a first outer wall portion <NUM> defining the first lumen <NUM> and a second outer wall portion <NUM> defining the second lumen <NUM>. The first lumen <NUM> is defined by the first outer wall portion <NUM> and the partition <NUM>, and the second lumen <NUM> is defined by the second outer wall portion <NUM> and the partition <NUM>.

Although the use of the catheter of this embodiment is not limited in terms of which direction is the upward, downward, rightward, or leftward direction of the catheter, the following description assumes the following: With respect to the partition <NUM>, the upper side is the side on which the first lumen <NUM> is located, and the lower side is the side on which the second lumen <NUM> is located. In addition, it is assumed that, with the first lumen <NUM> being on the upper side, the right side when the body <NUM> is viewed from the distal end side is referred to as a right-side surface, and the left side is referred to as a left-side surface.

In the hemodialysis using the catheter of this embodiment, to perform normal forward connection, the first lumen <NUM> serves as a blood removal lumen, and the second lumen <NUM> serves as a blood return lumen. In addition, in order to solve problems such as sticking to the blood vessel wall, it is also possible to perform reverse connection in which the first lumen <NUM> and the second lumen <NUM> are used with their functions exchanged. To perform such a reverse connection, the second lumen <NUM> serves as a blood return lumen, and the first lumen <NUM> serves as a blood removal lumen.

The first lumen <NUM> and the second lumen <NUM> are symmetrical with each other with respect to the partition <NUM>. This configuration results in that the first lumen <NUM> and the second lumen <NUM> have an equal cross-sectional area, so that the amount of blood removed via the second lumen <NUM> can be easily ensured in the reverse connection as well. In addition, extrusion molding for manufacturing the body <NUM> is facilitated. Optionally, to ensure the amount of blood removed via the first lumen <NUM> in the forward connection, the partition <NUM> may be positioned in such a way that the first lumen <NUM> has a cross-sectional area greater than that of the second lumen <NUM>.

The first lumen <NUM> and the second lumen <NUM> are semi-circular in cross-section. This configuration ensures large cross-sectional areas of the first lumen <NUM> and the second lumen <NUM> by effectively utilizing the inner cavity of the body <NUM>. With this configuration, the amount of blood removed via the first lumen <NUM> can be secured and the suction pressure can be lowered to make the sticking to the blood vessel wall difficult, during the forward connection. This configuration can also bring about the same effect for the second lumen <NUM> during the reverse connection.

The outer diameter φ of the body <NUM> is not particularly limited, but may be preferably <NUM> or greater, or more preferably <NUM> or greater in light of ensuring the blood flow rate. Moreover, for the sake of the insertability into blood vessels, the outer diameter of the body <NUM> may be preferably <NUM> or smaller, or more preferably <NUM> or smaller.

The thickness of the outer wall <NUM> of the body <NUM> is not particularly limited, but may be preferably <NUM> or thicker, or more preferably <NUM> or thicker, in light of the strength of the catheter. Moreover, in light of the flexibility of the catheter, the thickness of the outer wall <NUM> of the body <NUM> may be preferably <NUM> or less, or more preferably <NUM> or less.

The catheter of this embodiment is of end hole-type with the first lumen <NUM> and the second lumen <NUM> each having a distal end opening, which opens toward a distal end of the body <NUM>. The second lumen <NUM> has a second opening plane <NUM> at its distal end, and the first lumen <NUM> has a first opening plane <NUM> at its distal end, and the second opening plane <NUM> is positioned more distally than the first opening plane <NUM>. In the catheter of this embodiment, the second opening plane <NUM> is positioned at the distal end of the body <NUM>. With this configuration, the body <NUM> has such a distal end that has a smaller cross-sectional area than in a configuration in which the first opening plane <NUM> and the second opening plane <NUM> coincide with each other in the longitudinal direction, thereby improving the catheter in insertability. Moreover, with this configuration, recirculation, in which the blood returned via the second lumen <NUM> is sucked into the first lumen <NUM> immediately after the return, becomes more difficult to occur during the forward connection.

It is preferable that the first opening plane <NUM> is distanced from the second opening plane <NUM> as much as allowed, for the sake of the insertability of the catheter and of avoiding the recirculation during the forward connection. Specifically, a distance L1, which is a distance from the distal end of the body <NUM> (i.e., the second opening plane <NUM>) to the first opening plane <NUM>, may be preferably <NUM> or longer, or more preferably <NUM> or longer. In view of the length of the catheter, it is preferable that the distance from the distal end of the body <NUM> be not too long. Specifically, the distance L1, which is the distance from the distal end of the body <NUM> (i.e., the second opening plane <NUM>) to the first opening plane <NUM>, may be preferably <NUM> or shorter, or more preferably <NUM> or shorter.

The partition <NUM> extends from the proximal end to the distal end of the body <NUM>. The width of the partition <NUM> is constant from the proximal end of the body <NUM> to the position of the first opening plane <NUM>, and becomes gradually narrower from the position of the first opening plane <NUM> to the distal end of the body <NUM>. The second outer wall portion <NUM> is configured such that the inner cavity of the second lumen <NUM> becomes gradually smaller toward the distal end of the body <NUM> in accordance with the change in the width of the partition <NUM>. This configuration enables the catheter to be insertable with less resistance and less damaging to the blood vessel. Where to start the narrowing of the width of the partition <NUM> is not particularly limited. The width of the partition <NUM> may start to gradually narrow from any starting position, as long as the starting position is more distal than the first opening plane <NUM>.

The first outer wall portion <NUM> is trimmed in such a way that the first outer wall portion <NUM> becomes farther from the partition <NUM> toward the proximal end, so that first opening plane <NUM> is declined with respect to the partition <NUM> toward the proximal end. This configuration enables the catheter to be insertable with less resistance and less damaging to the blood vessel, compared with a configuration in which the first opening plane <NUM> is orthogonal to the partition <NUM>. Further, the inclination gives the first opening plane <NUM> a larger size (a larger opening plane area) than that in the case where the first opening plane <NUM> is orthogonal to the partition <NUM>. With this configuration, the suction pressure can be reduced to make the sticking to the blood vessel wall difficult in the forward connection. Furthermore, this configuration enables to easily ensure the amount of blood removed via the first lumen <NUM>.

The first opening plane <NUM> and the partition <NUM> forms an opening angle θ1 that may be preferably <NUM>° or less, or more preferably <NUM>° or less, for the sake of the insertability of the catheter. On the other hand, in light of preventing blood removal failure caused by the first opening plane <NUM> sticking to the blood vessel wall due to the suction pressure during the forward connection, the opening angle θ1 may be preferably <NUM>° or more, or more preferably <NUM>° or more.

The second opening plane <NUM> is orthogonal to the partition <NUM>. This configuration can make it difficult for the sticking to the blood vessel wall to occur in the reverse connection.

The first outer wall portion <NUM> has a first lumen slit <NUM> obtained by notching a portion of the distal end of the first outer wall portion <NUM>. The first lumen slit <NUM> has a predetermined width. With such a configuration, the flow of blood sucked into the first lumen <NUM> is dispersed also into the first lumen slit <NUM> during forward connection. This reduces the suction pressure, thereby making it difficult for the sticking to the blood vessel wall to occur. With this configuration, even if the first opening plane <NUM> is clogged due to thrombus or the like, the first lumen <NUM> can be kept open.

The first lumen slit <NUM> is provided in a circumferential middle portion of the first outer wall portion <NUM>. This configuration allows the catheter to be indwelled in the blood vessel without lowering the rigidity of the first outer wall portion <NUM>. In addition, this configuration enables to prevent clogging or narrowing of the first opening plane <NUM> that would be caused by pressing from the blood vessel wall or the like.

The first lumen slit <NUM> may be formed by notching from the distal end of the first outer wall portion <NUM> and heating the notch. In this way, the first lumen slit <NUM> can be easily formed without requiring a complicated process. In addition, according to this configuration, burrs are less likely to be generated in the formation of the first lumen slit <NUM>, and thus this configuration is excellent in safety.

The length L2 of the first lumen slit <NUM> is not particularly limited, but may be preferably not shorter than <NUM> but not longer than <NUM>, or more preferably not shorter than <NUM> but not longer than <NUM>, for the sake of reducing the sticking to the blood vessel wall.

The width of the first lumen slit <NUM> is not particularly limited, but may be preferably not shorter than <NUM> but not longer than <NUM>. Moreover, the width of the first lumen slit <NUM> may be preferably in a range of <NUM> % to <NUM>% of an outer diameter φ of the catheter, for the sake of ensuring the rigidity of the first outer wall portion <NUM>. The width of first lumen slit <NUM> is constant in the longitudinal direction in this embodiment, but is not limited thereto and may vary along the longitudinal direction. For example, the width of the first lumen slit <NUM> may be gradually widened from the distal end to the proximal end of the first lumen slit <NUM>.

The distal end portion of the first outer wall portion <NUM> has (a) first lumen side pore(s) <NUM> allowing the first lumen <NUM> to communicate with the outside of the first lumen <NUM>. With such a configuration, the flow of blood sucked into the first lumen <NUM> is further dispersed during the forward connection, thereby further making it difficult for the sticking to the blood vessel wall to occur. Moreover, this configuration enables to easily ensure the amount of blood removed via the first lumen <NUM>. Furthermore, this configuration enables to keep the first lumen <NUM> open even if the first opening plane <NUM> and/or the first lumen slit <NUM> is/are clogged due to thrombus or the like.

It is preferable to provide a plurality of the first lumen side pores <NUM> at intervals in the longitudinal direction, in order to attain a greater effect of dispersing the suction pressure. The catheter of this embodiment is illustrated as having two first lumen side pores <NUM>, but the number of the first lumen side pores <NUM> is not limited thereto and may be three or more.

For the sake of reducing the sticking to the blood vessel wall, it is preferable that the first lumen side pore(s) <NUM> be displaced from the first lumen slit <NUM> as much as possible, and it is more preferable that the first lumen side pore(s) <NUM> be positioned more proximally than the first lumen slit <NUM>. Moreover, the sticking to the blood vessel wall can be further reduced by making the positions of the plurality of the first lumen side pores <NUM> displaced, that is, staggered from each other in both the longitudinal direction and the width direction of the first lumen <NUM>.

In the configuration in which the positions of the first lumen side pores <NUM> are staggered, it is preferable that positions of first lumen side pores <NUM> adjacent to each other be displaced as much as possible. For example, such two first lumen side pores <NUM> adjacent to each other may be preferably positioned such that lines connecting either one of adjacent two first lumen side pores <NUM> with the center of a circle formed by the outer wall <NUM> form an angle in a range of <NUM>° to <NUM>°. It is preferable that the first lumen side pores <NUM> be on opposite sides across the first lumen slit <NUM>.

It is preferable that the first lumen side pores <NUM> be positioned at equal intervals in the longitudinal direction. For example, such two first lumen side pores <NUM> adjacent to each other may be preferably arranged at such a longitudinal interval that the length of a straight line connecting the centers of the first lumen side pores <NUM> assumingly aligned straightly in the longitudinal direction be in a range of <NUM> to <NUM>. The first lumen side pores <NUM> may be arranged at inconstant intervals in the longitudinal direction. The positions of the first lumen side pores <NUM> are not limited to the staggering arrangement, but may be aligned straightly in the longitudinal direction.

The diameter(s) of the first lumen side pore(s) <NUM> is/are not particularly limited, but may be preferably not smaller than <NUM>, but not greater than <NUM>. A part of the plurality of the first lumen side pores <NUM> may differ from the others in their diameters. Moreover, the first lumen side pore(s) <NUM> may be provided as needed, and the catheter may be configured without the first lumen side pore(s) <NUM>.

The body <NUM> includes a flexible portion <NUM>. The flexible portion <NUM> has a lower hardness than the other portion <NUM> of the body <NUM> other than the flexible portion <NUM>. The flexible portion <NUM> includes the distal end portion of the first outer wall portion <NUM>, in which the first lumen slit <NUM> is formed.

As illustrated in <FIG>, the distal end portion, included in the flexible portion <NUM>, of the first outer wall portion <NUM> is a portion S that extends from the distal end to a position corresponding to at least the middle of the length L2 of the first lumen slit <NUM> within the portion that includes the first lumen slit <NUM> of the first outer wall portion <NUM>. Thus, the flexible portion <NUM> includes the portion S, which is at least a distal half of the portion including the first lumen slit <NUM>, of the first outer wall portion <NUM>. Note that the flexible portion <NUM> may cover further extended area, and, for example, may be configured to include the entire portion including the first lumen slit <NUM>.

These configurations bring about the following effect: At the catheter insertion, the catheter is deformed in such a way that the distal end portion of the first outer wall portion <NUM> bends into the inner cavity of the first lumen <NUM> from both sides of the first lumen slit <NUM>. This allows the catheter to have the following excellent insertability: At the insertion, the cross-sectional area of the body <NUM> at the first opening plane <NUM> becomes smaller, so that the first opening plane <NUM> will not be a cause of significant insertion resistance. In addition, this allows for reduction in the burden on the patient and the operator. The distal end portion of the first outer wall portion <NUM> returns to its original shape when the catheter is indwelled in the blood vessel. This allows for an excellent insertability of the catheter without affecting the function of the first lumen <NUM>.

The flexible portion <NUM> may preferably include such a part of the portion, including the first lumen slit <NUM>, of the first outer wall portion <NUM> that extends from the position of the proximal end of the first lumen slit <NUM> to the distal end of the portion. With this configuration, the first outer wall portion <NUM> becomes more easily deformable from both sides of the first lumen slit <NUM> in such a way that the first outer wall portion <NUM> bends into the inner cavity of the first lumen <NUM> from where the proximal end of the first lumen slit <NUM> is located. This allows the catheter to have such a more excellent insertability, because, at the insertion, the cross-sectional area of the body <NUM> at the first opening plane <NUM> becomes further smaller, so that the insertion resistance changes more gradually.

Moreover, the flexible portion <NUM> may preferably range from the position of the proximal end of the first lumen slit <NUM> to the distal end of the body <NUM> (i.e., the second opening plane <NUM>). This configuration allows the catheter to have an excellent insertability and makes the catheter less damaging to the blood vessel in passing through the blood vessel.

In the configuration in which the flexible portion <NUM> ranges from the position of the proximal end of the first lumen slit <NUM> to the distal end of the body <NUM> (i.e., the second opening plane <NUM>), the longitudinal range of the flexible portion <NUM> from the distal end of the body <NUM> may be preferably <NUM> or longer, or more preferably <NUM> or longer, for the sake of the insertability of the catheter. On the other hand, for the sake of operability of the catheter, the longitudinal range of the flexible portion <NUM> from the distal end of the body <NUM> may be preferably <NUM> or shorter, or more preferably <NUM> or shorter.

The flexible portion <NUM> may be formed of a material such as polyurethane, polyvinyl chloride, silicone, an ethylene-vinyl acetate copolymer, or a polyamide. Among them, the flexible portion <NUM> may be preferably formed of polyurethane.

In addition, the other portion <NUM> than the flexible portion <NUM> in the body <NUM> is required to be stable in shape in the blood vessel and to have hardness to an extent that does not damage the blood vessel. In view of this, the other portion <NUM> than the flexible portion <NUM> may be formed of a material such as polyurethane, polyvinyl chloride, silicone, polyethylene, polypropylene, an ethylene-vinyl acetate copolymer, or a polyamide. Moreover, among them, the other portion <NUM> than the flexible portion <NUM> may be preferably formed of polyurethane, because polyurethane has such a hardness that does not impair the insertability of the catheter and polyurethane is hard at room temperatures, but becomes softer at internal body temperatures. The flexible portion <NUM> and the other portion <NUM> than the flexible portion <NUM> may be preferably formed of the same material for the sake of easy welding, but may be formed of different materials.

In a case where the other portion <NUM> than the flexible portion <NUM> is made of a material whose flexibility decreases significantly as temperature rises, the flexible portion <NUM> and the other portion <NUM> other than the flexible portion <NUM> have a predetermined difference in hardness at room temperatures before catheter insertion. On the other hand, at the catheter insertion in a blood vessel and warmed up at an internal body temperature, the hardness of the other portion than the flexible portion <NUM> decreases significantly, so that the difference in hardness between the flexible portion <NUM> and the other portion <NUM> than the flexible portion <NUM> becomes smaller than before the insertion. This configuration prevents the catheter from bending at a boundary between the flexible portion <NUM> and the other portion <NUM> than the flexible portion <NUM> inside the blood vessel, thereby making the catheter less damaging to the blood vessel, even though the insertability of the catheter is still maintained.

The distal end of the body <NUM> may have a color different from the color of the other portion of the body <NUM>. This facilitates the operator to recognize the position of the distal end of the body <NUM>, thereby improving the operability of the catheter. At least a portion of the body <NUM> may be formed of a material containing a contrast agent such as barium sulfate, bismuth tungstate, or bismuth oxide, so as to facilitate finding out where the catheter is inserted.

The length of the body <NUM> is not particularly limited, but may be preferably <NUM> or longer, or more preferably <NUM> or longer, but preferably <NUM> or shorter, or more preferably <NUM> or shorter, as an indwelling portion of the catheter.

The body <NUM> is provided with branch pipes 103A and 103B extending from the proximal end of the body <NUM> via a branch portion <NUM>. A distal end of the branch pipe 103A is connected to the first lumen <NUM>. Moreover, the distal end of the branch pipe 103B is connected to the second lumen <NUM>. Each of the proximal ends of the branch pipes 103A and 103B is provided with a connector (not shown) connected thereto. The connectors, which are covered respectively with protection caps 131A and 131B in the illustrations in <FIG>, allow the body <NUM> to be connected to a blood circuit and the like via the connectors.

The branch pipe 103A is provided with a clamp 132A attached thereto, whereas the branch pipe 103B is provided with a clamp 132B attached thereto. By providing the branch pipes 103A and 103B respectively with the clamps 132A and 132B, the branch pipes 103A to 103B becomes closable for performing a treatment such as heparin rock.

The catheter of this embodiment can be modified in various ways. In the following variations, only portions different from this embodiment will be described. The description of the configuration common to the present embodiment will be omitted as appropriate. In addition, like portions are denoted with like reference numerals as in this embodiment.

According to a first variation, as illustrated in <FIG>, the first opening plane <NUM> may be orthogonal to the partition <NUM>. This configuration enables to make it difficult for the sticking to the blood vessel wall to occur in the forward connection. In the first variation, at the catheter insertion, the first outer wall portion <NUM> is deformed from the both sides of the first lumen slit <NUM> in such a way that the distal end portion of the first outer wall portion <NUM> goes into the inner cavity of the first lumen <NUM>. This allows for preventing the first opening plane <NUM> orthogonal to the partition <NUM> from becoming an insertion resistance.

According to a second variation, as illustrated in <FIG>, the distal end of the second outer wall portion <NUM> may have a second lumen slit <NUM>. With such a configuration, the flow of blood sucked into the second lumen <NUM> is dispersed, reducing the suction pressure during reverse connection, thereby making it difficult for the sticking to the blood vessel wall to occur. This configuration enables to make it difficult for recirculation to occur in the reverse connection.

The second lumen slit <NUM> may be provided preferably in a circumferential middle portion of the second outer wall portion <NUM>, for the sake of preventing rigidity reduction of the second outer wall portion <NUM>. The length of the second lumen slit <NUM> is not particularly limited, but may be preferably <NUM> or longer or <NUM> or shorter for the sake of reducing the sticking to the blood vessel wall. Moreover, the width of the second lumen slit <NUM> is not particularly limited, but may be preferably <NUM> or wider, but <NUM> or narrower, and preferably in a range of <NUM>% to <NUM>% of the outer diameter φ of the catheter, in light of ensuring the rigidity of the second outer wall portion <NUM>.

In the second variation, the flexible portion <NUM> includes, in addition to the distal end portion of the first outer wall portion <NUM>, that distal end portion of the second outer wall portion <NUM>, in which the second lumen slit <NUM> is provided. Here, the distal end portion of the second outer wall portion <NUM> included in the flexible portion <NUM> is a part of the portion in which the second lumen slit <NUM> of the second outer wall portion <NUM> is provided, the part at least ranging from the half of the length of the second lumen slit <NUM> to the distal end. Therefore, it is sufficient that the flexible portion <NUM> provided in the second outer wall portion <NUM> includes the distal half of the portion in which the second lumen slit <NUM> of the second outer wall portion <NUM> is provided, and the flexible portion <NUM> may include the entire portion in which the second lumen slit <NUM> is provided.

This configuration brings about the following effect: At the catheter insertion, the catheter is deformed in such a way that the distal end portion of the second outer wall portion <NUM> bends into the inner cavity of the second lumen <NUM> from both sides of the second lumen slit <NUM>. With this configuration, at the insertion, the cross-sectional area of the body <NUM> at the second opening plane <NUM> becomes smaller, thereby providing the catheter with an excellent insertability. The distal end portion of the second outer wall portion <NUM> returns to its original shape when the catheter is indwelled in the blood vessel. This allows for an excellent insertability of the catheter without affecting the function of the second lumen <NUM>.

The flexible portion <NUM> provided on the first outer wall portion <NUM> and the flexible portion <NUM> provided on the second outer wall portion <NUM> may be separate portions or a continuous portion. Specifically, the configuration where the flexible portions <NUM> are separate portions may be, for example, the following case: The flexible portions <NUM> are provided respectively at the portion including the distal end portion of the first outer wall portion <NUM> and at the portion including the distal end portion of the second outer wall portion <NUM>. Moreover, the configuration where the flexible portions <NUM> are a continuous portion may be, for example, the following case: The flexible portion <NUM> ranges from the position in the body <NUM> at which the proximal end of the first lumen slit <NUM> is located, to the distal end of the body <NUM> (second opening plane <NUM>).

According to a third modified example (not shown), from the viewpoint of preventing recirculation in the reverse connection, the second variation may be further modified such that the first opening plane <NUM> and the second opening plane <NUM> are provided together at the distal end of the body <NUM> so as to be coincided longitudinally, and the partition <NUM> is extended more distally than the positions of the first opening plane <NUM> and the second opening plane <NUM>. In this configuration, the recirculation in reverse connection is more difficult to occur than in the configuration in which the second opening plane <NUM> is more distal than the first opening plane <NUM>.

Moreover, in the third variation, the second outer wall portion <NUM> has a second lumen slit <NUM> and the flexible portion <NUM> includes, in addition to the distal end portion of the first outer wall portion <NUM>, that distal end portion of the second outer wall portion <NUM> on the both sides of the second lumen slit <NUM>. This configuration brings about the following effect: At the catheter insertion, the catheter is deformed in such a way that the first outer wall portion <NUM> and the second outer wall portion <NUM> bend into the inner cavities of the first lumen <NUM> and the second lumen <NUM>. Thus, even in the configuration in which the first opening plane <NUM> and the second opening plane <NUM> are coincided longitudinally, the cross-sectional area at the distal end of the body <NUM> can become smaller, thereby obtaining an excellent insertability of the catheter.

The third variation is especially preferable in the case where the catheter is inserted with the aid of an introducer sheath. When inserting the catheter into an inner cavity of the introducer sheath, the first outer wall portion <NUM> and the second outer wall portion <NUM> are deformed, so that the check valve can pass through the inner cavity easily. Furthermore, the recirculation in reverse connection can be reduced by the partition <NUM> extended more distally beyond the positions of the first opening plane <NUM> and the second opening plane <NUM>.

According to a fourth variation, as illustrated in <FIG>, the distal end portion of the second outer wall portion <NUM> may have a plurality of the second lumen side pores <NUM> communicating the second lumen <NUM> with the outside, the plurality of the second lumen <NUM> including a second lumen side pore <NUM> being elliptical in shape and long in the longitudinal direction. This can reduce the suction pressure in the reverse connection, thereby making it difficult for the sticking to the blood vessel wall to occur. Moreover, this configuration enables to easily ensure the amount of blood removed via the second lumen <NUM>. Furthermore, this configuration can keep the second lumen <NUM> open by the plurality of second lumen side pores <NUM> even if the second opening plane <NUM> is clogged due to thrombus or the like.

The size of the second lumen side pore <NUM> being elliptical in shape is not particularly limited, but may be preferably as large (long and wide) as the second lumen slit <NUM>, for the sake of reducing the sticking to the blood vessel wall.

The second lumen side pore <NUM> being elliptical in shape brings about a more advantageous effect than the second lumen slit <NUM>, for example, when inserting the catheter by the Seldinger technique. Specifically, in performing the Seldinger technique, in the case of the configuration provided with the second lumen slit <NUM>, insertion of the catheter with the aid of a stylet for filing a gap between the blood return lumen and a guide wire would cause a distal end of the stylet to stick out of the second lumen <NUM> via the second lumen slit <NUM>, thereby damaging the blood vessel with the stylet or adversely affecting the operability of the catheter. On the other hand, the elliptical shape of the second lumen side pore <NUM> is closed loop-shaped, such sticking-out of the stylet will not occur and an excellent operability can be obtained.

Moreover, the distal end portion of the second outer wall portion <NUM> has a plurality of second lumen side pores <NUM> being circular in shape. The positions of the plurality of the second lumen side pores <NUM> being circular in shape may be preferably staggered from each other as in the case of the first lumen side pores <NUM>, for the sake of reducing the sticking to the blood vessel wall in the reverse connection. While the fourth variation is illustrated as including two second lumen side pores <NUM> being circular in shape, three or more second lumen side pores <NUM> may be provided and the plurality of the second lumen side pores <NUM> may be aligned straightly in the longitudinal direction.

It is preferable that the second lumen side pore(s) <NUM> be positioned more distally than the position of the proximal end of the first lumen slit <NUM>, for the sake of reducing the recirculation.

In the fourth variation, the flexible portion <NUM> includes the distal end portion of the first outer wall portion <NUM>, the distal end portion having the first lumen slit <NUM>. For facilitating the formation of the plurality of second lumen side pores <NUM>, it is preferable that the flexible portion <NUM> do not include the distal end portion of the second outer wall portion <NUM>. This configuration prevents breakage of the peripheries of the second lumen side pores <NUM>, thereby ensuring the strength of the peripheries of the second lumen side pores <NUM>, during hemodialysis.

The flexible portion <NUM> may include the distal end portion of the second outer wall portion <NUM>, for example, in such a way that the flexible portion <NUM> ranges from the position of the proximal end of the first lumen slit <NUM> to the distal end of the body <NUM>. This configuration brings about the following effect: At the catheter insertion, the distal end portion of the second outer wall portion <NUM> can be easily deformed, so that the second lumen side pore(s) <NUM> is/are narrowed or closed to reduce the cross-sectional area of the second lumen <NUM>, thereby improving the insertability of the catheter. In the configuration in which the flexible portion <NUM> includes the distal end portion of the second outer wall portion <NUM>, the distal end portion of the second outer wall portion <NUM> may be thick, for the sake of preventing breakage of the peripheries of the second lumen side pore(s) <NUM>.

While the fourth variation is illustrated such that the plurality of the second lumen side pores <NUM> includes an elliptical one, all the plurality of the second lumen side pores <NUM> may be circular in shape. Optionally, the plurality of second lumen side pores <NUM> may be all elliptical in shape with no second lumen side pore <NUM> circular in shape, and the number of the second lumen side pores <NUM> is not particularly limited and may be one or more.

In the fourth variation, the cross sections of the distal end and the proximal end of the body <NUM> are similar to those of the catheter according to the present embodiment.

According to a fifth variation, as illustrated in <FIG>, the distance L1 from the first opening plane <NUM> to the distal end of the body <NUM> may be long, so that a plurality of the second lumen side pores <NUM> is provided in the distal end portion of the second outer wall portion <NUM>. The long distance L1 allows the distal end portion of the second outer wall portion <NUM> to have a greater area, thereby ensuring places for positioning the plurality of second lumen side pores <NUM>. In addition, this configuration can improve the insertability of the catheter by suppressing a rapid change in insertion resistance. The plurality of second lumen side pores <NUM> is provided, so that the flow of blood sucked into the second lumen <NUM> can be dispersed during the reverse connection, thereby making it difficult for the sticking to the blood vessel wall to occur.

The plurality of second lumen side pores <NUM> may be preferably provided at intervals in the longitudinal direction for the sake of dispersing the suction pressure during the reverse connection. It is preferable that the plurality of second lumen side pores <NUM> be positioned more distally than the first opening plane <NUM>, for the sake of reducing the recirculation. While the fifth variation is illustrated as including two second lumen side pores <NUM>, the number of the second lumen side pores <NUM> is not particularly limited, and three or more second lumen side pores <NUM> may be provided.

In view of reducing the sticking to the blood vessel wall, the positions of the plurality of second lumen side pores <NUM> may be preferably staggered. In this case, it is preferable that the positions of adjacent second lumen side pores <NUM> be displaced from each other as much as possible. The positions of the second lumen side pores <NUM> are not limited to the staggering arrangement, but may be aligned straightly in the longitudinal direction. Moreover, the fifth variation may further include a second lumen side pore <NUM> being elliptical in shape.

In the fifth variation, the flexible portion <NUM> may include the distal end portion of the first outer wall portion <NUM>, the distal end portion including the first lumen slit <NUM>, while the flexible portion <NUM> does not include the distal end portion of the second outer wall portion <NUM> for the sake of including the plurality of the second lumen side pores <NUM>. This configuration prevents breakage of the peripheries of the second lumen side pores <NUM>, thereby ensuring the strength of the peripheries of the second lumen side pores <NUM>, during hemodialysis. Note that the flexible portion <NUM> may include the distal end portion of the second outer wall portion <NUM>. In this case, the distal end portion of the second outer wall portion <NUM> may be thick, for the sake of preventing breakage of the peripheries of the second lumen side pore(s) <NUM>.

The fifth variation is such that the distance L1 from the distal end of the body <NUM> (the second opening plane <NUM>) to the first opening plane <NUM> may be preferably <NUM> or shorter, or more preferably <NUM> or shorter, for the sake of securing the place of providing the plurality of second lumen side pores <NUM>, while improving the insertability of the catheter.

According to a sixth variation, as illustrated in <FIG>, the distal end of the second outer wall portion <NUM> may have a second lumen slit <NUM> and the second lumen side pore <NUM>. With this configuration, the second lumen slit <NUM> can prevent the second outer wall portion <NUM> from sticking to the blood vessel wall in the longitudinal direction while the second lumen side pore <NUM> can prevent the second outer wall portion <NUM> from sticking to the blood vessel wall in the circumferential direction.

Moreover, as in the second variation and the third variation, the sixth variation is configured such that the flexible portion <NUM> includes, in addition to the distal end portion of the first outer wall portion <NUM>, the distal end portion, including the second lumen slit <NUM>, of the second outer wall portion <NUM>. This configuration brings about the following effect: At the catheter insertion, the catheter is deformed in such a way that the distal end portion of the second outer wall portion <NUM> bends into the inner cavity of the second lumen <NUM> from both sides of the second lumen slit <NUM>. This brings about the following effect: At the insertion, the cross-sectional area of the body <NUM> at the second opening plane <NUM> becomes smaller, thereby providing the catheter with an excellent insertability.

According to a seventh variation, as illustrated in <FIG>, the inner space of the body <NUM> may be partitioned with the partition <NUM> into three lumens including the first lumen <NUM>, the second lumen <NUM>, and a third lumen. The third lumen may be used as a route for drug solution administration, central venous pressure measurement, or the like.

A third opening plane <NUM> at a distal end of the third lumen is provided more distally than the first opening plane <NUM> and the second opening plane <NUM>, and positioned at the distal end of the body <NUM>. This configuration allows for the following recirculation: The drug solution supplied into the blood vessel via the third lumen is sucked into the first lumen <NUM> immediately after the administration can be prevented during the forward connection. Moreover, with this configuration, the drug solution supplied via the third lumen is carried away from the first opening plane <NUM> with the flow of the blood returned via the second lumen <NUM> and the flow of the blood flowing through the blood vessel, thereby making it difficult for the recirculation to occur. Since the third opening plane <NUM> is positioned more distally than the second opening plane <NUM>, the recirculation hardly occurs during the reverse connection as well.

The third lumen may have a smaller cross-sectional area than those of the first lumen <NUM> and the second lumen <NUM>, for the sake of ensuring the blood flow rate of blood flowing through the first lumen <NUM> and the second lumen <NUM> and of the efficiency of the hemodialysis.

In the seventh variation, the first lumen slit <NUM> is provided at the distal end of the first outer wall portion <NUM> and the second lumen slit <NUM> is provided at the distal end of the second outer wall portion <NUM>. Moreover, the flexible portion <NUM> includes the distal end portion of the first outer wall portion <NUM>, the distal end portion including the first lumen slit <NUM>, and the distal end portion of the second outer wall portion <NUM>, the distal end portion including the second lumen slit <NUM>.

This configuration brings about the following effect: At the catheter insertion, the catheter is deformed in such a way that the second outer wall portion <NUM> bends into the inner cavity of the second lumen <NUM> at the second opening plane <NUM> and the first outer wall portion <NUM> bends into the inner cavity of the first lumen <NUM> at the first opening plane <NUM>. With this configuration, at the insertion, the cross-sectional area of the body <NUM> becomes smaller respectively at these opening planes, thereby attaining an excellent insertability of the catheter. According to the seventh variation, the flexible portion <NUM> may range from the position of the proximal end of the first lumen slit <NUM> to the distal end of the body <NUM>.

As in the present embodiment and each variation, the seventh variation may include the first lumen side pore(s) <NUM> and the second lumen side pore(s) <NUM>. In the case where the seventh variation is configured such that the distal end portion of the second outer wall portion <NUM> includes the plurality of second lumen side pores <NUM>, it is preferable that lines connecting either one of adjacent two second lumen side pores <NUM> and the center of the circle formed by the outer wall <NUM> form an angle in a range of <NUM>° to <NUM>°, for example. For other configurations than the configuration described above, the catheter of the seventh variation is not particularly limited.

According to an eighth variation, as illustrated in <FIG>, the inner space of the body <NUM> may be partitioned with the partition <NUM> into four lumens including the first lumen <NUM>, the second lumen <NUM>, the third lumen, and a fourth lumen. Like the third lumen, the fourth lumen may be used as a route for drug solution administration, central venous pressure measurement, or the like. In the eighth variation, providing two lumens in addition to the blood removal and blood return lumens, enables to eliminate the need for preparing a new route in case where a plurality of drug solutions is to be administered, thereby reducing the burden on an operator and the patient. The catheter may be configured to include more lumens.

A fourth opening plane <NUM> at a distal end of the fourth lumen is provided more distally than the first opening plane <NUM>, the second opening plane <NUM>, the third opening plane <NUM>, and positioned at the distal end of the body <NUM>. This configuration enables to prevent recirculation of the drug solution supplied into the blood vessel via the fourth lumen during the forward connection. This configuration enables to prevent recirculation of the drug solution supplied via the fourth lumen during the reverse connection.

The fourth lumen may have a smaller cross-sectional area than those of the first lumen <NUM> and the second lumen <NUM>, for the sake of securing the blood flow rate of blood flowing through the first lumen <NUM> and the second lumen <NUM> and for the sake of the efficiency of the hemodialysis.

According to the eighth variation, the first lumen slit <NUM> is provided at the distal end of the first outer wall portion <NUM> and a second lumen slit <NUM> is provided at the distal end of the second outer wall portion <NUM>. Moreover, the flexible portion <NUM> includes the distal end portion of the first outer wall portion <NUM>, the distal end portion including the first lumen slit <NUM>, and the distal end portion of the second outer wall portion <NUM>, the distal end portion including the second lumen slit <NUM>.

As in the seventh variation, this configuration can bring about the following effect: At the catheter insertion, the first outer wall portion <NUM> and the second outer wall portion <NUM> are deformed, thereby attaining an excellent insertability of the catheter. In the eighth variation, the flexible portion may range from the position of the proximal end of the first lumen slit <NUM> to the distal end of the body <NUM>.

As in the present embodiment and each variation, the eighth variation may include the first lumen side pore(s) <NUM> and the second lumen side pore(s) <NUM>. In the case where the eight variation is configured such that the distal end portion of the first outer wall portion <NUM> includes the plurality of first lumen side pores <NUM>, it is preferable that the lines connecting either one of adjacent two first lumen side pores <NUM> and the center of the circle formed by the outer wall <NUM> form an angle in a range of <NUM>° to <NUM>°, for example, and the same is applied in the configuration in which the plurality of second lumen side pores <NUM> is provided. Other than the configuration described above, the catheter of the eighth variation is not particularly limited.

The variations may be further modified as below.

For example, the second, third, and sixth to eighth variations including the second lumen slit <NUM> are not limited to the configurations above in which the flexible portion <NUM> includes, in addition to the distal end portion of the first outer wall portion <NUM>, the distal end portion of the second outer wall portion <NUM>. In these variations, it is sufficient that the flexible portion <NUM> includes at least the distal end portion of the first outer wall portion <NUM>, so that the flexible portion <NUM> may not include the distal end portion of the distal end portion of the second outer wall portion <NUM>. With the configuration in which the flexible portion <NUM> includes at least the distal end portion of the first outer wall portion <NUM>, the distal end portion of the first outer wall portion <NUM>, which has such a large outer diameter that would hinder the insertion, can be improved with a better insertability.

The catheters according to the variations may be configured such the proximal end of the body <NUM> is connectable with a branch pipe, a connector, or the like via a branch portion, as necessary.

The catheters of the present embodiment and the variation may be cuffed at a proximal location on the body <NUM> with a cuff made of synthetic fibers, as necessary, for the sake of preventing catheter-indwelling-induced infection during long-term indwelling.

Claim 1:
A multi-lumen catheter, comprising:
a body (<NUM>) that is formed into a cylindrical shape and extends from a proximal end to a distal end and surrounded by an outer wall (<NUM>),
an inner space of the body (<NUM>) being divided with a partition (<NUM>) extending in a longitudinal direction, into a plurality of lumens including a first lumen (<NUM>) and a second lumen (<NUM>),
the second lumen (<NUM>) having a second opening plane (<NUM>) at a distal end thereof, and the first lumen (<NUM>) having a first opening plane (<NUM>) at a distal end thereof, the second opening plane (<NUM>) being positioned more distally than the first opening plane (<NUM>),
the outer wall (<NUM>) including a first outer wall portion (<NUM>) defining the first lumen (<NUM>) and a second outer wall portion (<NUM>) defining the second lumen (<NUM>),
characterized in that
the first outer wall portion (<NUM>) has a first lumen slit (<NUM>) notching a portion of a distal end of the first outer wall portion (<NUM>),
the body (<NUM>) includes a flexible portion (<NUM>) having a lower hardness than other portions of the body (<NUM>), and
the flexible portion (<NUM>) includes a distal end portion of the first outer wall portion (<NUM>), the distal end portion including the first lumen slit (<NUM>).