JP2007037971A - Catheter assembly and sheath tearing assist - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily insert a split tip catheter which is difficult to be inserted and indwelled in a simple constitution without impairing its patency. <P>SOLUTION: This catheter assembly comprises a catheter having one part inserted and indwelled in the blood vessel by Seldinger method, and a sheath covering the catheter; the catheter comprises a double lumen part integrally formed with a first lumen and a second lumen in parallel to each other, a first branch tube and a second branch tube extended to one side of the double lumen part, and an extension tube connecting part provided in the other side of the double lumen part; the lumen of the first branch tube is communicated with the first lumen, the lumen of the second branch tube is communicated with the second lumen, and the first branch tube is longer than the second branch tube; and the sheath has an approximately tubular shape, covers the first branch tube, the second branch tube and the double lumen part, is torn along a shaft, and the adjacency of the tip of the first branch tube is swelled so as to be slidably but tightly stuck to the inside of the tip of the sheath. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention has good patency, and even if it is placed in a blood vessel for a long period of time, the blood removal port is not blocked by a thrombus or blood vessel wall, so that a desired blood flow volume can be secured, and insertion and placement in the blood vessel can be performed. The present invention relates to an easy catheter assembly and a sheath tear aid.

  Hemodialysis is a treatment in which the blood of patients with renal failure, drug poisoning, fulminant hepatitis, etc. is taken out of the body, toxins and water are removed in an artificial kidney, and the cleaned blood is returned to the body. This treatment takes several hours at a time and takes place several times a week. For this reason, it is necessary to take out a blood stably for a long period of time, and an intake (ejecting blood outlet), and a catheter for hemodialysis is often used to make such an escaped blood outlet.

  Although the catheter for hemodialysis is used for such a need, in particular, with one catheter, blood can be taken out of the body (blood removal) and blood can be returned to the body (blood feeding). A double-lumen catheter that is convenient for insertion into a blood vessel and can efficiently secure a blood flow is widely used.

  However, a major problem with this double-lumen catheter is that the opening, which is the outlet for blood removal in the blood vessel, is gradually blocked by thrombus and the blood vessel wall due to long-term placement in the blood vessel, and sufficient blood flow is obtained. It is easy to disappear.

  In recent years, as long-term patency can be obtained, a method of inserting and placing two single lumen catheters side by side for blood removal and blood transmission has been performed. The difference from the conventional method in which an integral double lumen catheter is inserted and indwelled is considered that in this method, blood flows all around the tip of each catheter, and the blockage of the opening is suppressed.

  It has also been reported that this method reduces the amount of fibrin and other substances that accumulate near the tip of each single-lumen catheter that moves into the bloodstream and moves independently.

  However, the method of inserting and placing two single-lumen catheters side by side is very troublesome because even if one catheter is inserted and placed, it is difficult to insert and place two catheters. Moreover, since there are two catheter insertion parts, infection control is troublesome.

  Therefore, as a catheter incorporating only the advantages of the above-mentioned two, a catheter (split tip catheter) having a structure in which a double lumen catheter on the proximal side and a distal side branch to form two catheters is disclosed in US Pat. No. 6001079. It is proposed in the issue gazette.

  However, this catheter has the disadvantage that it is very difficult to insert into a blood vessel. When this catheter is inserted and placed, for example, a guide wire is placed in the blood vessel in advance, the wall of the longer branch tube is skewed with this guide wire, and the guide wire is inserted into the distal end opening of the shorter branch tube. In this state, the catheter is inserted into the blood vessel. However, when the catheter is inserted by this method, the insertion resistance of the catheter is very large, and insertion is not possible unless the insertion site is largely incised beforehand. .

  As another insertion method, there is a method in which a sheath is previously placed in a blood vessel and a catheter is inserted through the lumen of the sheath. Specifically, a guide wire is first placed, and a sheath / dilator set is inserted along the guide wire. Thereafter, the dilator is removed leaving the sheath in the blood vessel. The catheter tip is inserted into this sheath and pushed to a predetermined position. Next, the sheath is pulled out, but the sheath is pulled back little by little so that the catheter is not pulled back, the portion that has come out of the body is sequentially divided, and this is repeated over the entire length to divide into two, and then removed.

  A major problem with this method is the backflow of air from the sheath port. The cervical vena cava, where dialysis catheters are preferably placed, has low blood pressure and can easily become negative pressure due to patient breathing, drawing air from the sheath mouth and causing complications such as air embolism. For this reason, when the operator pulls out the dilator from the sheath, it is necessary to immediately close the sheath opening. Also, when inserting the catheter, it is necessary to quickly put two branches, short and long, into the sheath to minimize air entrainment. Another problem is that it requires two steps: placement of the sheath and insertion of the catheter.

Another problem is that since the wall cross-sectional area of the split portion is larger than that of the main body portion, the lumen becomes smaller and the blood flow volume is reduced accordingly.
US Patent No. 6001079 US Pat. No. 5,947,953

  The problem to be solved is that it is difficult to insert the split tip catheter into the blood vessel in the procedure of inserting the split tip catheter into the blood vessel. Another problem is that the lumen becomes smaller at the split part and the blood flow is suppressed.

  In the present invention, in order to facilitate insertion into a blood vessel, the distal end of the bifurcated portion on the front side of the split tip catheter is covered with a sheath, leaving the distal end of the split tip catheter in contact with the sheath tip. The main feature is to expand the vicinity of the tube in contact with the sheath to minimize the gap with the sheath and to make the tip into a truncated cone.

  That is, the catheter assembly according to the present invention includes a catheter partially inserted and indwelled in a blood vessel by the Seldinger method, and a sheath covering the catheter. The catheter has a first lumen and a second lumen. A double lumen part formed integrally in parallel; a first branch pipe and a second branch pipe extended on one side of the double lumen part; and provided on the other side of the double lumen part And a lumen of the first branch pipe communicates with the first lumen, a lumen of the second branch pipe communicates with the second lumen, and the first branch pipe The branch pipe is longer than the second branch pipe, and the sheath is substantially tubular, and covers the first branch pipe, the second branch pipe, and the double lumen portion in a round bar shape along the axis. It is designed to be torn by hand, and the vicinity of the tip of the first branch pipe is And it is characterized in that the bulged to slidably contact the inner side of the distal end of the sheath.

  Here, it is preferable that the vicinity of the distal end of the sheath is slightly reduced in diameter in the vicinity of the distal end of the first branch pipe and is slidably adhered to the first branch pipe. Moreover, it is preferable that the front-end | tip part of said 1st branch pipe is gradually diameter-reduced toward the front end side. The first lumen is used as a blood supply lumen, the second lumen is used as a blood removal lumen, the first branch tube is used as a blood supply branch tube, and the second branch tube is used as a blood removal branch tube. be able to.

  Moreover, you may form all or one part of said 1st branch pipe and said 2nd branch pipe over the perimeter, or only for a part of circumference | surroundings with the water-absorbing swelling material. Moreover, you may form a part of the opposing side of said 1st branch pipe and / or said 2nd branch pipe with a water absorptive swelling raw material.

  Further, the sheath tearing assisting tool according to the present invention comprises a regulating portion that regulates the spread of the sheath so as to be slidable from the side at one side of the double lumen portion when the sheath is torn. And a stop portion that holds down the other side of the double lumen portion and prevents the double lumen portion from coming out to the other side when tearing.

  Here, the stop part may be a stop part (stopper) inserted into the joining part of the first extension tube and the second extension tube, and grips any part of the other side of the double lumen part. A gripping tool may be used.

  Further, another sheath tearing aid according to the present invention includes a ring-shaped fixing portion, a pair of wing portions formed integrally with the fixing portion on both sides of the fixing portion, and each end of the torn sheath And a pair of wings, the pair of wings is provided with a hole for passing a torn sheath, and the diameter of the hole is smaller than the outer diameter of the knob. To do.

  In the catheter assembly of the present invention, the two branch pipes on the front side of the split tip catheter are combined with a sheath, and the tip is formed into a single round bar-like body with a truncated cone shape. An advantageous effect is that a simple split tip catheter can be easily inserted and placed in a blood vessel.

  In the catheter assembly of the present invention, the two branch pipes on the front side of the split tip catheter are integrated together with a sheath so that the catheter and the sheath can be inserted simultaneously, so that air flows back from the sheath port into the blood vessel. There is an effect that there is no fear of doing.

  In the catheter assembly of the present invention, the vicinity of the distal end of the first branch tube is swelled so as to be slidably in contact with the inside of the distal end of the sheath, so that the catheter can be smoothly inserted and placed in the blood vessel. There is an effect that can be done.

  Further, the catheter assembly of the present invention has a structure in which the vicinity of the distal end of the sheath is slightly reduced in diameter near the distal end of the first branch pipe and is slidably adhered to the first branch pipe. Can be smoothly inserted and placed in the blood vessel.

  In addition, the catheter assembly of the present invention smoothly inserts and indwells a catheter in a blood vessel when the distal end of the first branch pipe is gradually reduced in diameter toward the distal end to form a truncated cone. There is an effect that can be.

  Further, the catheter assembly of the present invention has a structure in which all or a part of the first branch pipe and the second branch pipe are formed of a water-swellable material over the entire circumference. Since the tube is swollen by moisture in the blood and the lumen is expanded, there is an effect that a desired blood flow rate can be secured.

  Further, the catheter assembly of the present invention has a structure in which all or a part of the first branch pipe and the second branch pipe are formed of a water-swellable material over the entire circumference. Since the tube swells due to moisture in the blood and becomes thicker, the first branch tube and the second branch tube are prevented from being bent.

  Further, the catheter assembly of the present invention has a configuration in which all or a part of the first branch pipe and the second branch pipe are formed of a water-swellable material only in a part of the circumference. It is possible to suppress a decrease in the tensile strength of the branch pipe when it is formed from a water-absorbing swellable material, and it is also possible to suppress a decrease in the fusion force with the double lumen portion. Furthermore, since the expansion of the water-swellable material portion in the axial direction is suppressed, the expansion in the radial direction is increased and the lumen sectional area can be increased.

  In addition, the catheter assembly of the present invention can be obtained when the first branch tube and / or the second branch tube on the opposite side is formed of a water-swellable material when inserted into a blood vessel. In addition, since the portion swells locally, the first branch pipe and / or the second branch pipe bend to the opposite side, and the access between the first branch pipe and the second branch pipe is prevented, This has the effect of preventing the deposition of fibrin or the like in the blood removal port.

  In addition, the sheath tear assisting tool of the present invention has an effect that the sheath can be easily torn and removed by one person without removing the inserted and indwelling catheter.

  The purpose of enabling easy insertion of a split-tip catheter that is difficult to place is achieved with a simple configuration without impairing the patency of the catheter.

  FIG. 1 is a perspective view of a catheter assembly according to one embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of a distal end portion of the catheter assembly of FIG. As shown in these drawings, the catheter assembly 10 includes a split tip catheter 12 and a sheath 14 covering the split tip catheter 12.

  The distal end portion of the split tip catheter 12 slightly protrudes from the distal end of the sheath 14. A stylet 16 is inserted into the split tip catheter 12, and the distal end of the stylet 16 protrudes from the distal end of the split tip catheter 12.

  3 is a perspective view of the split tip catheter inside the catheter assembly of FIG. 1, FIG. 4 is a cross-sectional view taken along the line AA in FIG. 3, FIG. 5 is a cross-sectional view taken along the line BB in FIG. Is a sectional view taken along the line CC of FIG. 3, and FIG. 7 is a longitudinal sectional view of the distal end portion of the split tip catheter of FIG.

  As shown in FIG. 3, the split tip catheter 12 is provided on the other side of the double lumen portion 18, a branch tube 20 that is formed to extend on one side of the double lumen portion 18, and the other side of the double lumen portion 18. The extension tube connecting portion 36 is connected to the extension tube connecting portion 36.

  The double lumen portion 18 is formed of a cylindrical body. As shown in FIG. 4, a first lumen 24 and a second lumen 26 each formed of a cavity are integrally formed in parallel inside the double lumen portion 18.

  The branch pipe 20 includes a first branch pipe 28 and a second branch pipe 30. As shown in FIG. 5, the first branch pipe 28 is formed of a cylindrical body having a substantially semicircular cross section, and a hole inside the first branch pipe 28 is connected to the first lumen 24. As shown in FIG. 5, the second branch pipe 30 is also formed of a cylindrical body having a substantially semicircular cross section, and a hole inside the second branch pipe 30 is connected to the second lumen 26.

  The first branch pipe 28 is longer than the second branch pipe 30, and the tip of the first branch pipe 28 has a partially thickened wall as shown in FIGS. 6 and 7. As getting thicker. A gentle outer shape is continuously formed from the distal end portion of the first branch pipe 28 to the distal end portion of the sheath 14.

  The extension tube 22 connects the catheter 12 to the dialysis machine and includes a first extension tube 32 and a second extension tube 34. The first extension tube 32 is formed of a cylindrical body having a substantially circular cross section, and the hole inside the first extension tube 32 is connected to the first lumen 24 via the extension tube connecting portion 36. The second extension tube 34 is also formed of a cylindrical body having a substantially semicircular cross section, and a hole inside the second extension tube 34 is also connected to the second lumen 26 via the extension tube connecting portion 36.

  The first branch tube 28, the first lumen 24, and the first extension tube 32 are used for blood feeding, and the second branch tube 30, the second lumen 26, and the second extension tube 34 are used for blood removal. .

  As the material of the split tip catheter 12, polyurethane, nylon elastomer, silicon rubber, or the like is used. In particular, polyurethane has appropriate flexibility and strength, and it is possible to secure a sufficient blood flow by designing the lumen to be large, and it is less likely to bend and block the lumen, and to damage the blood vessel wall. It is a suitable material.

  The branch pipe 20 does not need to be made of the same material and the same hardness as long as it can be firmly bonded or fused to the double lumen portion 18. The extension tube 22 can also be made of the same material as the double lumen portion 18. A softer one is selected if necessary.

  The sheath 14 is made of a thin plastic cylindrical body. The material of the sheath 14 is preferably a material that has strength and rigidity, such as polyethylene, polypropylene, nylon elastomer, and fluororesin, and does not collapse even if it is thinly formed.

  The splitting property of the sheath 14 is imparted by using a blend of single or plural materials, adding orientation in the longitudinal direction at the time of tube forming or in a later process, and tearing from any surrounding direction, or A plurality of weak lines can be provided along the longitudinal direction of the tube.

  Next, a method for inserting and placing a catheter in a blood vessel by the Seldinger method using this catheter assembly will be described.

  First, an introduction needle for introducing a guide wire is inserted into a blood vessel from the outside of the skin, the guide wire is inserted into the blood vessel via the introduction needle, and the introduction needle is removed.

  Next, a guide wire is put into the inside from the front end of the stylet 16 inserted into the catheter assembly 10, the guide wire is taken out from the rear end portion of the stylet 16, and the catheter assembly 10 is inserted along the guide wire into the insertion site. Get close to. Then, the distal end of the sheath 14 is pushed into the skin along the guide wire, inserted into the blood vessel, and then the guide wire is removed.

  Next, the sheath 14 is removed. When the sheath 14 is removed, for example, a sheath tearing aid 38 as shown in FIG. 8 is used. The sheath tearing assisting tool 38 is inserted into a restricting portion 40 that restricts the spread of the sheath so that it can slide from the side when tearing the sheath 14, and a stop inserted into the joining portion of the first extension tube 32 and the second extension tube 34. The restricting portion 40 and the stop portion 42 are integrally formed by a connecting member 44.

  The sheath tearing aid 38 is a hard and slippery material and is preferably made of high-density polyethylene, polypropylene, or the like that is easy to injection mold.

  The sheath 14 is also pulled out at the regulating portion 40 by pulling both ends to the left and right to pull out the inner sheath inserted into the blood vessel. If the sheath 14 is pulled without using the sheath tearing aid 38, the catheter 12 is pulled out together with the sheath 14. However, when the sheath 14 is pulled left and right, the sheath 14 pushes the restricting portion 40 back to the body side, Since the stop part 42 integrated with the restricting part 40 presses the catheter 12 back in the direction of the body, the catheter 12 is not pulled out.

  For sheath tearing, for example, a sheath tearing tool as shown in FIG. 9 may be used. The sheath tearing tool 38 includes a ring-shaped fixing portion 46 fitted into the extension tube connecting portion 36, and a pair of wing portions 48, 48 formed integrally with the fixing portion 46 on both sides of the fixing portion 46. And a pair of knobs 50 and 50 connected to each end of the torn sheath 14. Each wing 48 and 48 has a hole 52 through which the torn sheath 14 is passed, and the diameter of the hole 52 is smaller than the outer diameter of the knob 50. The fixing portion 46 is completely fixed to the extension tube connecting portion 36 or is rotatably fixed.

  The sheath 14 is pulled out by pulling the knobs 50, 50 to the left and right, and the sheath 14 inserted in the blood vessel is pulled out, and is torn between the wings 48, 48 and in front of the fixed part 46. If the sheath 14 is pulled without using the sheath tearing aid 38, the catheter 12 is pulled out together with the sheath 14. However, when the sheath 14 is pulled left and right, the sheath 14 pushes the sheath tearer 38 together with the catheter back to the body side. Because of the pressing, the catheter 12 is not pulled out.

  The sheath tearing tool 38 can be used as it is as a member for fixing the catheter to the skin after tearing out the sheath 14.

  The stylet 16 to be applied is slidably mounted in the lumen of the split tip catheter 12 as necessary, for the purpose of increasing the rigidity of the catheter 12 and making it easier to push into the body, or the tip of the blood supply side branch tube Although it is used for the purpose of filling the gap between the opening and the guide wire to be applied and reducing the resistance of insertion, a strong and hard material is preferable, and high-density polyethylene, polypropylene, nylon, or the like is used.

  For the purpose of simply increasing rigidity, either a solid or hollow stylet can be used, but for the purpose of filling the latter gap, it must be hollow and allow the guidewire to be inserted through it.

  The wall thickness of the first branch pipe 28 and the second branch pipe 30 is preferably equal to or greater than the wall thickness of the double lumen portion 18 in order to prevent bending. For this reason, the lumens of both the branch pipes 28 and 30 are narrower than the lumen of the double lumen portion 18, and blood flow is restricted. Therefore, as shown in FIGS. 10 to 12, all or part of the first branch pipe 28 and the second branch pipe 30 may be formed of a water-absorbing swellable material over the entire circumference.

  When all or part of the first branch tube 28 and the second branch tube 30 are formed of a water-swellable material over the entire circumference, when the catheter 12 is inserted into blood, the first branch tube As shown in FIG. 11 (b), the inner branch 28 and the second branch tube 30 swell due to the moisture in the blood, and the inner diameter expands from h1 to h2 (h1 <h2), thereby improving blood circulation.

  Further, when the first branch pipe 28 and the second branch pipe 30 are made of a water-swellable material, but a part is made of a hydrophobic material, as shown in FIG. A decrease in the tensile strength of the tube 28 and the second branch tube 30 can be suppressed, and the fusion with the double lumen portion can be made more reliable.

  Moreover, when the water-absorbing swellable material swells by absorbing moisture in the blood, as shown in FIG. 13B, the first branch pipe 28 and the second branch pipe 30 have a semicircular shape. It swells closer to a circle, and the cross-sectional area of its lumen expands more greatly, improving blood circulation.

  In the present invention, since the first branch pipe 28 and the second branch pipe 30 are accommodated in the sheath 14, the first branch pipe 28 and the second branch pipe 30 are placed in the narrow sheath 14 for a long time. There is a possibility that it is restrained and has a habit and remains close even if it is released from the sheath 14 in the blood vessel. The first branch pipe 28 and the second branch pipe 30 are separated to some extent within the blood vessel, so that blood flows around the entire circumference, preventing the opening from being blocked, and accumulation of fibrin and the like is prevented. It is said that the performance will not be demonstrated if they are close to each other. Therefore, as shown in FIGS. 14A and 15, a part of the second branch pipe 30 on the side facing the first branch pipe 28 may be formed of a water-swellable material.

  When a part of the second branch tube 30 opposite to the first branch tube 28 is formed of a water-swellable material, when the catheter 12 is inserted into the blood, the water-swellable material portion is As shown in FIG. 14 (b), the second branch tube 30 bends and separates from the first branch tube 28, making it difficult for fibrin and the like in the blood to accumulate and opening. The potential is improved.

  Manufacture example 1: JIS hardness 90 degree, made of aromatic isocyanate polyurethane containing 20% barium sulfate, double lumen part 18 is 12Fr × 10 cm, length of first branch pipe 28 is 12 cm, second branch pipe The length of 30 was 7 cm, and the catheter 12 was molded. The branch pipes 28 and 30 and the double lumen portion 18 were joined by passing a cored bar through the respective lumens and covering each other with a silicon heat-shrinkable tube, heat-shrinking, and fusing them together.

  The first branch pipe 28 is shaped so that the outer shape is a circle of 15 Fr to 15 mm from the tip of the first branch pipe 28, the front is narrowed into a conical shape, and the proximal side is gradually reduced over 10 mm. It was restored to its shape. A hollow stylet made of nylon was attached over the entire length of the blood supply lumen, and the tip was projected forward from the first branch tube 28 by 10 mm. A 13.5Fr fluororesin-splitting sheath 14 was placed on the sheath and set so that the tip was 20 mm from the tip of the first branch tube 28.

  Production example 2: A double-lumen portion 18 of 12 Fr × 10 cm is formed of aliphatic isocyanate polyurethane containing 20% barium sulfate with a Shore D hardness of 65 degrees, and the same material with a Shore A hardness of 85 degrees is made of the first branch pipe. The catheter 12 was molded with the length of 28 being 10 cm and the length of the second branch tube 30 being 6 cm.

  The junction between the branch pipes 28 and 30 and the double lumen portion 18 is made by passing a cored bar through the respective lumens and pressing them against each other, covering them with silicon heat-shrinkable tubes, and heat-shrinking them to fuse them together. . A hollow stylet made of PP was attached over the entire length of the blood supply lumen, and the tip was projected forward from the first branch tube 28 by 10 mm. Further, a solid stylet made of PP was attached to the blood removal side so that the tip was located 5 mm before the tip of the second branch tube 30.

  A split sheath 14 containing a 13.5 Fr PP weak line was placed on the split tip catheter 12 and set so that the tip was 20 mm from the tip of the first branch tube 28. A PP sheath tearing aid 38 was attached to the extension tube connecting portion 36.

It is a perspective view of the catheter assembly concerning one example of this invention. FIG. 2 is a longitudinal sectional view in the vicinity of a distal end portion of the catheter assembly of FIG. 1. FIG. 2 is a perspective view of a split tip catheter inside the catheter assembly of FIG. 1. It is AA arrow sectional drawing of FIG. It is a BB arrow sectional view of Drawing 3. It is CC sectional view taken on the line of FIG. FIG. 4 is a longitudinal sectional view of a main part of the split tip catheter of FIG. 3. It is explanatory drawing which shows the state which mounted | wore the catheter assembly with the sheath tear assistance tool. It is explanatory drawing which shows the state which mounted | wore the other sheath tearing aid with the catheter assembly. It is a longitudinal cross-sectional view of the tip part vicinity of the split tip catheter which concerns on the other Example of this invention. It is DD sectional view taken on the line of FIG. It is EE sectional drawing of FIG. It is sectional drawing of the branch pipe of the split tip catheter which concerns on the other Example of this invention. It is a longitudinal cross-sectional view of the tip part vicinity of the split tip catheter which concerns on the other Example of this invention. It is FF arrow sectional drawing of Fig.14 (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Catheter assembly 12 Split tip catheter 14 Sheath 16 Stylet 18 Double lumen part 20 Branch pipe 22 Extension tube 24 First lumen 26 Second lumen 28 First branch pipe 30 Second branch pipe 32 First extension tube 34 Second extension tube 36 Extension tube connecting part 38 Sheath tear assisting tool 40 Restricting part 42 Stopping part 44 Connecting member 46 Fixing part 48 Wing part 50 Knob part 52 Hole

Claims (12)

  A double lumen comprising a catheter partially inserted and placed in a blood vessel by the Seldinger method and a sheath covering the catheter, wherein the first lumen and the second lumen are integrally formed in parallel. A first branch pipe and a second branch pipe formed to extend on one side of the double lumen part, and an extension tube connecting part provided on the other side of the double lumen part, The lumen of the first branch is in communication with the first lumen, the lumen of the second branch is in communication with the second lumen, the first branch is longer than the second branch, The sheath has a substantially tubular shape, covers the first branch tube, the second branch tube, and the double lumen portion in a rod shape, and is torn by hand along an axis. The vicinity of the tip of the first branch pipe is slidably in contact with the inside of the tip of the sheath. Catheter assembly which is characterized in that characterized in that bulged manner.   The catheter assembly according to claim 1, wherein the vicinity of the distal end of the sheath is reduced in diameter in the vicinity of the distal end of the first branch pipe and is in close contact with the first branch pipe.   The catheter assembly according to claim 1 or 2, wherein a distal end portion of the first branch pipe is gradually reduced in diameter toward the distal end side. The catheter assembly according to any one of claims 1 to 3, wherein the distal end portion of the first branch pipe is gradually reduced in diameter toward the double lumen portion side.   The first lumen is a blood supply lumen, the second lumen is a blood removal lumen, the first branch tube is a blood supply branch tube, and the second branch tube is a blood removal branch tube The catheter assembly according to any one of claims 1 to 4.   The whole or a part of said 1st branch pipe and said 2nd branch pipe is formed with the water-absorbing swelling raw material over the perimeter, The one in any one of Claims 1-5 characterized by the above-mentioned. Catheter assembly.   The whole or a part of the first branch pipe and the second branch pipe is formed of a water-absorbing material at a part of the circumference. Catheter assembly.   The catheter set according to any one of claims 1 to 5, wherein a part of the first branch pipe and / or the second branch pipe on the opposite side is formed of a water-swellable material. Solid.   A restricting portion for restricting the spread of the sheath so as to be slidable from one side of the double lumen portion when the sheath is torn, and on the other side of the double lumen portion when the sheath is torn A sheath tearing assisting device comprising: a stop portion that holds the portion and stops the double lumen portion from coming off to the other side.   The sheath tear assisting device according to claim 9, wherein the stop portion includes a stop portion inserted into a joining portion of the first extension tube and the second extension tube.   The sheath tearing assisting tool according to claim 9, wherein the stop portion is formed of a gripping tool for gripping any portion on the other side of the double lumen portion.   A ring-shaped fixing part, a pair of wing parts formed integrally with the fixing part on both sides of the fixing part, and a pair of knobs connected to each end of the torn sheath; A sheath tearing assisting tool, wherein a hole for passing a torn sheath is formed in the pair of wing parts, and the diameter of the hole is smaller than the outer diameter of the knob part.

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