BACKGROUND OF THE INVENTION In many cases of biliary surgery including the common bile duct, gallbladder and liver, biliary drainage is considered to be necessary. For this purpose tube method"using a T shaped rubber tube which is inserted directly into the common bile duct has been used all over the world for more than 90 years. However, this method has serious drawbacks : a high complication ratio and a need for long-term hospitalization.

The inventor of the present invention has developed a new technique for bile drainage, which is called as"C tube method". The technique uses a thin drainage tube of a couple of millimeters in diameter, and the tube is inserted via the cystic duct into the common bile duct of cholecystectomized patients. The way of tube insertion to the common bile in C tube method is quite

different from that in T tube method. In the former the tube is inserted to the common bile duct via the cystic duct, on the other hand in the latter (T tube method) it is inserted directly to the common bile duct. Through a number of cholecystectomized cases combined with a concomitant drainage tube insertion, it has been proved that C tube method avoids postoperative complications by enabling a secure bile drainage and results in short hospital stay. Therefore, C tube method is very useful and effective for biliary drainage in comparison with T tube method.

The technical summary of the procedure would be as follows. First, a thin drainage tube made of flexible material, which is called"C tube", is inserted through the cystic duct into the common bile duct. The name"C tube" was named by the invertor, which in the beginning it was called"Cystic duct tube", and then"C tube", for distinguishing it from"T tube". Then, the tube is fixed to the cystic duct by winding and fastening an elastic surgical suture around the cystic duct utilizing endoscopic clips for its fixation. At this moment, since the tube is made of flexible material for the purpose of its insertion from the angled cystic duct to the common bile duct and avoidance of CBD injury due to the tube, the ligation of the tube by an elastic suture may result in an unwanted

choking or narrowing of the tube. Otherwise, a loosen fastening may result in an unwanted withdrawal of the tube from the cystic duct and could cause severe postoperative complications due to bile leakage into the abdominal cavity.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to develop biliary drainage method which contributes to the patient's QOL (quality of life) by diminishing postoperative complications and a short-term hospitalization. To realize it, a new drainage tube (C tube) was invented, which prevents the unwanted choking of the tube at the fixation portion of the tube.

Accordingly, the drainage tube assembly according to the present invention has a flexible body with a distal and a proximal end. It has a suitable outer diameter capable of being inserted into the common bile duct via the cystic duct. A handling block provided at the distal end of the drainage tube defines a first passage and a second passage branched from the first passage. The first passage is communicated at its one end with the distal end of the drainage tube. The second passage is connected with a side tube. In particular, a metal sleeve is secured around the drainage tube so that a part of the drainage tube covered by the metal sleeve still maintains an

original inner diameter thereof.

In another aspect of the present invention, the tube assembly has a guide wire which is sized to be able to be inserted from the other end of the first passage of the block and then into the drainage tube.

In another aspect of the present invention, the guide wire has a holder fixed at a proximal end thereof.

The holder is positioned so that, when the guide wire is fully inserted through the first passage of the connector into the drainage tube to the extent that the holder makes a contact with the block, the distal end of the guide wire protrudes from the distal end of the drainage tube.

In another aspect of the present invention, the assembly has a distal tube portion connected with the proximal end of the drainage tube. The distal tube portion is made of a flexible material and formed with a thinned portion, allowing the drainage tube to angle with the assembly.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side elevational view of a tube assembly according to the present invention in which a part of the drainage tube is omitted in the drawing; Fig. 2 is an exploded perspective view of an handling block connected at the proximal end of the

drainage tube; Fig. 3 is another exploded perspective view of the assembly; Fig. 4 is an enlarged perspective view of a part of the drainage tube; Fig. 5 is a perspective view of a guide wire in which a part of the guide wire is omitted from the drawing; Fig. 6 is an enlarged cross sectional view of the guide wire; and Fig. 7 is a schematic perspective view showing a surgical operation using the drainage tube according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the accompanied drawings, preferred embodiments of the drainage tube assembly will be described in detail hereinafter.

Referring first to Fig. 1, there is illustrated a C tube assembly of the present invention, generally indicated by reference numeral 10, for use in a bile drainage after biliary surgery.

The tube assembly 10 has a drainage tube 12 for the postoperative bile drainage from the common bile duct and for the injection of the contrast medium into the common bile duct for intraoperative or postoperative

cholangiography. For this purpose, the drainage tube 12 has a certain diameter and length capable of being inserted into the common bile duct via the cystic duct. For example, a tube having a length of about 60cm, an outer diameter of 1.72mm, and an inner diameter of 1.02mm is used for the drainage tube. Preferably, the drainage tube 12 is made of a flexible material such as polyurethane and designed so that it can bend smoothly with a large curvature while <BR> <BR> maintaining its original hollow section, i. e. , without any break, at the insertion from the cystic duct into the common bile duct angled with the cystic duct.

As best shown in Figs. 1 and 4, a distal peripheral edge 14 of the drainage tube 12 may be tapered or rounded so that it receives a minimum resistance at the contact with the inner surface of the cystic duct and the common bile duct at the insertion. Also, a distal portion of the drainage tube 12 has a plurality of apertures 16 defined therein at regular intervals of about 1cm with respect to its longitudinal direction. Preferably, the apertures 14 are positioned alternately on opposite sides of the drainage tube 12, which allows the drainage tube 12 to collect the bile from all directions and at different locations within the common bile duct.

In order to maintain an original size of the inner passage or lumen of the drainage tube 12 when it is

secured at cystic duct by an elastic surgical suture wound around the cystic duct together with the drainage tube, a metal sleeve 18 of 1cm length, which is made of stainless steel is fixed around the drainage tube 12 leaving a predetermined distance of about 5cm from the distal end of the drainage tube 12. Preferably, the sleeve 18 is made from a tube having a small thickness. This not only minimizes a risk of protrusion of the sleeve 18 from the outer peripheral surface of the drainage tube 12 but also prevents the size of the inner passage of the tube from being reduced. To this end, a metal tube having an inner diameter of 1.82mm and an outer diameter of 1.98mm is preferably used for the sleeve 18. The sleeve 18 is clamped around the tube 12 as it is evenly forced radially inwardly from all directions or symmetrically so that the clamped sleeve 18 keeps the outer diameter of about 1.75 to 1. 80mm. This ensures that after clamping of the sleeve the flexible tube 12 substantially maintains its original inner diameter.

Referring to Figs. 1 to 3, a handling block generally indicated by reference numeral 20 is connected at the proximal end of the tube assembly 10. The handling block 20 defines therein a first passage extending in a longitudinal direction and fluidly connected at its distal end with the drainage tube 12 and a second passage

branching off of and fluidly connected at its one end with the first passage.

As best shown in Figs. 2 and 3, the handling block 20 has a T-shaped, first component generally indicated by reference numeral 22 or tube made of polyvinyl chloride, for example. The first component 22 has a proximal tube portion 24, a tapered distal tube portion 26 connected with the distal end of the proximal tube portion 24 in a coaxial fashion and thereby defining a part of the first passage, an outward flange 28 formed between the proximal and distal tube portions 24 and 26, and a side tube portion 30 extending from the proximal tube portion 24.

In this embodiment, although the side tube portion 30 defining the second passage is extended perpendicularly from the proximal tube portion 24, it may be angled and oriented in any direction. Also, an external thread 32 is formed in an outer periphery of the proximal tube portion 24. Further, as best shown in Fig. 3, a concave or groove 34 is formed in a peripheral surface portion of the distal tube portion 26, adjacent to the outward flange 28.

A second component generally indicated by reference numeral 36 is provided for the connection between the first component 22 and the drainage tube 12. The second component 36 has a proximal tube portion 38 and a distal tube portion 40, connected with each other in a

coaxial fashion to define another part of the first passage.

In particular, an interior 42 of the proximal tube portion 38 is inwardly tapered for receiving the associated tapered distal tube portion 26 of the first component 22 and thereby forming a sealing engagement with the tapered distal tube portion 26. Also, the proximal tube portion 38 has an external thread 44 defined in its outer periphery.

Preferably, the distal tube portion 40 is integrally molded with the proximal tube portion 38 at the proximal end portion of the drainage tube 12. More preferably, the distal tube portion 40 is made of flexible material such as polyurethane while the proximal tube portion 38 is made of relatively rigid material such as polypropylene. In addition, a groove 46 is provided around the distal tube portion 40 to define a soft or thinned portion, which allows the distal tube portion 44 as well as the drainage tube 12 to be oriented in any directions without choking the passage.

A cylindrical coupler 48, which is preferably made of polypropylene, is used to connect between the first and second components 22 and 36. For this purpose, the coupler 48 is formed in its inner peripheral surface with an internal thread 50 at its distal end and an inward flange 52 at its proximal end. This allows the coupler 48 to be connected with the proximal tube portion 38 of the

second component 36 with its internal thread 50 engaged with the associated external thread 44 of the second component 36. For the coupler 48 so connected with the second component 36, the tapered distal tube portion of the first component 22 is inserted through the opening defined by the inward flange 52 into the corresponding tapered interior 42 of the second component 36 until the inward flange 52 engages with the groove 34 of the first component 22. Simultaneously with this engagement, the tapered distal tube portion 26 of the first component 22 makes a sealing contact with the inner surface of the tapered interior 42 of the second component 36. This simultaneous engagement and connection is ensured by adjusting the rotation of the coupler 48 relative to the second component 36.

A third component generally indicated by reference numeral 54 and defining another part of the first passage is connected at the proximal end of the first component 22. The third component 54, which is preferably made of polyvinyl chloride, has a proximal tube portion 56 defining an inwardly tapered passage 58 and a distal connecting portion 60 in the form of cylinder defining an cylindrical chamber 62 (see Fig. 3) communicated with the reduced distal end of the passage 58. Also, the cylindrical connecting portion 60 has an internal groove 64

(see Fig. 3) for the connection with a coupler generally indicated by reference numeral 66.

The coupler 66, which is preferably made of polypropylene, has a distal tube portion 68 having an inwardly tapered passage 70 defined therein and an outward flange 72 defined around the tube portion 68. Also, the coupler 66 has an inner tube portion 74 fluidly connected with the distal end of the passage 70 and an outer coupling portion 76 extending from the distal tube portion in an coaxial fashion with the inner tube portion 74. For connection with the first component 22, the outer coupling portion 76 has an internal thread 78 capable of engaging with the associated external thread 32 of the first component 22.

A valve pad 80 made of polyurethane and having a cut 82 at its center is positioned on the distal end of the coupler 66. Then, the proximal tube portion 68 of the coupler 66 is forced in the distal connecting portion 60 of the component 54, so that the external flange 72 engages with the inner groove 62 of the connecting portion 60.

This causes the valve pad 80 to be sandwiched between the proximal end of the coupler 66 and the opposing inner end surface of the proximal tube portion 56 of the component 60, connecting between the passage 58 of the component 54 and the passage 70 of the coupler 66 through the cut 82 of the

pad 80. Then, the third component 54 so assembled with the coupler 66 is connected with the first component 22 by the engagement of the external and internal threads 32 and 78.

The side tube portion 30 of the first component 22 is connected with a second tube 84 made of polyurethane.

The opposite end of the tube 84 is connected with a syringe connector 86. Typically, the connector 86 is closed with a suitable cap 88.

In order to guide the distal end of the drainage tube 12 into the cystic duct and then into the common bile duct, a guide wire 90 or stylet may be used. As shown in Fig. 2, the guide wire 90 is guided along a long and short dotted line through respective parts of the first passage defined in the components 54,22 and 36 into the tube 12.

Also, as described above, although the metal sleeve 18 is secured around the drainage tube 12, the original diameter of the drainage tube 12 is maintained even at the corresponding portion covered by the metal sleeve 18, allowing the guide wire 90 to pass the covered portion without any resistance.

Preferably, the guide wire 90 has an elevated elasticity so that, even when it is curved with a large curvature, it can recover its original straight configuration. To this end, as shown in Fig. 6 it is advantageous that the guide wire 90 is made of a core wire

92 and a spring wire 94 wound around the core wire 92.

More preferably, as shown in Figs. 2 and 5, a holder 96 is secured at one end of the guide wire 90 for its insertion and extraction without difficulty. In this instance, a length of the guide wire 90 from its distal end to the holder is determined so that, when the guide wire 90 is fully inserted into the drainage tube 12 with its holder 96 contact with the proximal end of the component 54, the distal end of the guide wire 90 projects a certain distance of about 10 to 15mm from the distal end of the drainage tube 12.

The catheter 10 so constructed is used for the bile drainage after biliary surgery. In this procedure, as shown in Fig. 7, the drainage tube 12 is inserted through the cystic duct 100 into the common bile duct 102 of cholecystectomized patients. At this moment, it is preferable that the distal end of the guide wire 90 is projected from the corresponding distal end of the drainage tube 12 and then inserted into the cystic duct, which ensures that the drainage tube 12 follows the guide wire 90 into the cystic duct and then into the common bile duct 102.

After the distal end of the drainage 12 is inserted in position in the common bile duct 102 and the metal sleeve 18 is located in the cystic duct, an elastic surgical suture 104 is wound and fastened around a portion

of the cystic duct 100 covering the metal sleeve 18. At this moment, the rigid metal tube 18 prevents the flexible drainage tube 12 from being choked, which can be caused by the elastic suture for fastening.

Before or after the fastening, the guide wire 90 is extracted from the drainage tube 12. Afterwards, physiological sodium chloride solution is injected through the side tube 84 by a syringe connected to the connector 86 to remove residual air in the passages of the handling block 20 and the drainage tube 12. At this moment, a part of the solution flows out from the proximal end of the handling block 20 through the cut 82 in the valve pad 80, so that no air remains even in the passage in the handling block 20. This further ensures that no air is co-injected from the drainage tube 12 into the common bile duct 102 when contrast medium is injected from the side 84 for for cholangiography intraoperatively or postoperatively, which can detect remnant stones or tumors in the biliary tract including common bile duct. It is important that while cholangiography is carrying out contamination of air bubbles should be strictly avoided because roentgenogramically air bubbles can not be differentiated from remnant stones or tumors.

Further, the handling block 20 defines the passage which is connected smoothly with the drainage tube

12, allowing a micro endoscope to be inserted through the drainage tube 12 into the common bile duct 102.

Although only preferred embodiments of the present invention are specifically disclosed and described above, it will be appreciated that many modifications and variations of the present invention are possible in light of the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the present invention.