in describing the embodiments of the invention illustrated in the drawings , specific terminology will be used for the sake of clarity . however , the invention is not intended to be limited to the specific terms so selected , it being understood that each specific term includes all technical equivalents operating in similar manner to accomplish similar purpose . it is understood that the drawings are not drawn exactly to scale . in the drawings , similar reference numbers are used for designating similar elements throughout the several figures . the following describes particular embodiments of the invention . however , it should be understood , based on this disclosure , that the invention is not limited to the embodiments detailed herein . generally , the following disclosure refers to dual or triple lumen catheter assemblies , although catheter assemblies having more lumens and / or distal end tubes are within the scope of the invention . further , the methods described below for making the catheter assemblies of the present invention are also applicable to making catheter assemblies having more than two lumens and / or distal end tubes . it is only for reasons of convenience that the following description refers to two or three lumen embodiments of the present invention . the multitube catheter assemblies of the present invention are inserted into an area of a body of a patient to be catheterized for removing and introducing fluids to the body . the catheter assemblies of the present invention are secured to a fixed location in or on the patient body , such as a subcutaneous area , before the catheter assembly is properly inserted and positioned in the area to be catheterized . this method is particularly preferred for long term catheterization . alternatively , in short term catheterization , the catheter assemblies of the present invention may be secured to an external surface of the body before or after the catheter assembly is properly inserted and positioned in the area to be catheterized . the multitube catheter assemblies of the present invention can be adapted for use in various applications in which bodily fluids , medicaments , or other solutions are introduced into and removed from the body , such as perfusion , infusion , plasmapheresis , hemodialysis , chemotherapy , and the like . the catheter assemblies of the present invention are particularly suitable for chronic hemodialysis and apheresis . the area to be catheterized is preferably a blood vessel , such as an internal jugular vein , but may be any suitable area within the body . other areas in which the catheter assemblies may be used include other blood vessels , including the femoral and subclavian veins , any cavity , and other areas of the body including intra - abdominal , sub - diaphragmatic and sub hepatic areas . it is understood that the above - referenced areas are exemplary , and that the catheter assemblies of the present invention may be used to remove or introduce fluids to various areas to be catheterized . the embodiments of the present invention shown in the figures are particularly useful for intake , or removal , of blood to be purified from a blood vessel , such as the internal jugular vein , and introduction of purified blood into the same vessel . the blood can be purified by any suitable hemodialysis apparatus attached in communication with lumens of the disclosed catheter assemblies . the catheter assemblies of the present invention may also be used to introduce medication or other fluids , including glucose or saline solutions , into the body . for purposes of describing the embodiments of the present invention shown in the figures , the catheter assemblies will be described with respect to an application of hemodialysis and or as channeling to the venous system . however , it is understood that the catheter assemblies of the present invention can be configured and adapted , by increasing or decreasing a size ( diameter or length ) and / or number of distal end tubes and / or lumens in the respective catheter assembly , so that the catheter assembly can be beneficially used for other medical applications in which fluids are introduced into and / or removed from the body . fig1 illustrates one embodiment of the present invention , where a catheter assembly has at least two lumens . the illustration of two lumens is exemplary , and the scope of the invention encompasses catheters having more than two lumens . the catheter assembly includes first tube t 1 which has a proximal end 101 and a distal end 103 . the catheter assembly includes second tube t 2 which has a proximal end 104 and a distal end 106 . the fist tube t 1 and the second tube t 2 united ( fused ) at catheter shaft tc as a result of fusion of a portion 104 of first tube t 1 and the 105 of second tube t 2 . the catheter assembly can be provided ( manufactured ) so that the first distal end tube d 1 and the second distal end tube d 2 are splitable ( releasable attached ) or separate at their respective distal ends . splitable is defined as releasable attached , meaning the first and the second distal end tubes d 1 and d 2 are fused , or otherwise attached , so that only minor force is necessary to pull apart , or split , along the imaginary line 118 . the first tube t 1 and second tube t 2 are split at the end of the catheter tube fused part tc at the point 108 and form free floating distal parts d 1 & amp ; d 2 . the multilumen catheter assembly includes a first lumen 112 and a second lumen 113 extending longitudinally therethrough as illustrated at c 1 . the first lumen 112 is continuous with and through the floating distal part d 1 , the catheter shaft tc and first extension tube e 1 . the second lumen 113 is continuous with and through the floating distal part d 2 , the catheter shaft tc and first extension tube e 2 . the first and the second extension tubes e 1 and e 2 lead to a proximal end of the catheter assembly , through which the materials entering and or exiting the patient enter and / or exit the catheter assembly . the words “ proximal ” and “ distal ” refer to directions away from and closer to , respectively , the inserted end of the catheter assembly . the exterior of the catheter shaft tc is smooth , rounded without ridges or grooves . as shown in the cross - section c 1 of the catheter shaft tc , the outer surface of the catheter shaft tc is generally rounded in shape ( outer configuration ), c 1 illustrating in cross - section a generally round shaped outer wall , with the first and the second lumens 112 , 113 having a circular cross - section . catheter shaft tc can have various shapes , such as but not limited to circular , semi - circular or oval . also lumen cross section can have various shapes , such as but not limited to circular , semi - circular or oval a cuff 114 may and may not be located at a point along the catheter shaft tc . cuffs are known in the art and provide a surface onto which internal tissue may adhere to stabilize the catheter assembly within the patient . in the above mentioned embodiments , it is noted that the proximal ends 101 , 104 may occur at different locations in various catheters . it is within the scope of the present invention to incorporate , in the dimensional aspects of length disclosed above , all locations where the proximal ends 101 , 104 could be said to occur in catheters known in the art , disclosed herein , or to be developed . the smooth generally round exterior surface of the catheter shaft tc passes through and remains positioned at a vessel wall insertion site during insertion of the catheter assembly into a patient . a vessel wall seals quite well around the smooth , round exterior surface of the catheter shaft tc , as shown in cross - section c 1 . since the exterior of the catheter shaft tc provides a good seal at the insertion site , the risk of blood loss around the catheter assembly at the insertion site is minimized . the first and the second distal end tubes d 1 , d 2 extend distally from the catheter shaft tc at the split point 108 . the first and the second distal end tubes d 1 , d 2 have outer surfaces continuous with the outer wall of the unitary catheter shaft tc , and are capable of independent movement when split from one another . the first and the second distal end tubes d 1 , d 2 are defined by circular outer walls . the first and the second lumens 112 , 113 are circular . the first and the second lumens 112 , 113 are always circular since circular cross sections are most conducive to fluid flow properties . however , other shapes such as d - shaped passageways and / or lumens , oval , triangular , square , elliptical , kidney - bean shaped passageways and / or lumens , or other configurations are also within the scope of the invention . further , while the catheter tubes t 1 , t 2 , the distal end tubes d 1 , d 2 , the lumens 112 , 113 and the proximal end tubes e 1 , e 2 are preferably identical in cross section , it is within the scope of the invention to vary the size , shape and / or configuration such that smaller distal end tubes and / or lumens , or varying types of lumens and distal end tubes may be used for other applications , such as an addition of a third , smaller lumen and corresponding distal end tube for introduction of medication . in addition to an l 1 & amp ; l 2 distal end opening , the first and the second distal end tubes d 1 , d 2 may or may not have a plurality of side holes 109 , 110 extending through exterior surfaces of the distal end tubes d 1 , d 2 to the first and the second lumens 112 , 113 . the side holes 109 , 110 provide additional or alternative flow paths . the side holes 109 , 110 can be arranged circumferentially and helically around the distal end tubes d 1 , d 2 to provide optimal flow properties , and to avoid suctioning of the distal tubes against an area to be catheterized , such as a vessel wall . the side holes 109 , 110 can be of various shape , but are typically circular or oval , or of some combination thereof and may also vary in number between the shorter and longer of the distal end tubes d 1 , d 2 . fig2 illustrates another embodiment of the present invention , where a catheter assembly has at least two lumens . the illustration of two lumens is exemplary , and the scope of the invention encompasses catheters having more than two lumens . the catheter assembly includes first tube t 1 which has a proximal end 101 and a distal end 103 . the catheter assembly includes a shorter second tube t 2 which has a proximal end 104 and a distal end 106 . the fist tube t 1 and the second tube t 2 united ( fused ) at catheter shaft tc as a result of fusion of a portion 104 of first tube t 1 and the 105 of second tube t 2 . the catheter assembly can be provided ( manufactured ) so that the first distal end tube d 1 is extending distally beyond the second tube distal end 106 . the multilumen catheter assembly includes a first lumen 112 and a second lumen 113 extending longitudinally therethrough as illustrated at c 1 . the first lumen 112 is continuous with and through the first tube t 1 from the distal end 103 of the floating distal part d 1 , the catheter shaft tc and first extension tube e 1 . the second lumen 113 is continuous with and through the second tube t 2 from the distal end 106 of the second tube t 2 , the catheter shaft tc and first extension tube e 2 . the first and the second extension tubes e 1 and e 2 lead to a proximal end of the catheter assembly , through which the materials entering and or exiting the patient enter and / or exit the catheter assembly . the words “ proximal ” and “ distal ” refer to directions away from and closer to , respectively , the inserted end of the catheter assembly . the exterior of the catheter shaft tc includes a smooth , rounded without ridges or grooves . as shown in the cross - section c 1 of the catheter shaft tc , the outer surface of the catheter shaft tc is generally rounded in shape ( outer configuration ), c 1 illustrating in cross - section a generally round shaped outer wall , with the first and the second lumens 112 , 113 having a circular cross - section . catheter shaft tc can have various shapes , such as but not limited to circular , semi - circular or oval . also lumen cross section can have various shapes , such as but not limited to circular , semi - circular or oval . a cuff 114 may or may not be located at a point along the catheter shaft tc . cuffs are known in the art and provide a surface onto which internal tissue may adhere to stabilize the catheter assembly within the patient . in the above mentioned embodiments , it is noted that the proximal ends 101 , 104 may occur at different locations in various catheters . it is within the scope of the present invention to incorporate , in the dimensional aspects of length disclosed above , all locations where the proximal ends 101 , 104 could be said to occur in catheters known in the art , disclosed herein , or to be developed . the smooth generally round exterior surface of the catheter shaft tc passes through and remains positioned at a vessel wall insertion site during insertion of the catheter assembly into a patient . a vessel wall seals quite well around the smooth , round exterior surface of the catheter shaft tc , as shown in cross - section c 1 . since the exterior of the catheter shaft tc provides a good seal at the insertion site , the risk of blood loss around the catheter assembly at the insertion site is minimized . the distal end tubes d 1 extend distally from the catheter shaft tc at the point 108 . the distal end tubes d 1 has outer surfaces continuous with the outer wall of the unitary catheter shaft tc , and are capable of independent movement . the first distal end tubes d 1 is defined by circular outer wall . the first and the second lumens 112 , 113 are circular . the first and the second lumens 112 , 113 are always circular since circular cross sections are most conducive to fluid flow properties . however , other shapes such as d - shaped passageways and / or lumens , oval , triangular , square , elliptical , kidney - bean shaped passageways and / or lumens , or other configurations are also within the scope of the invention . further , while the catheter tubes t 1 , t 2 , the distal end tube d 1 , the lumens 112 , 113 and the proximal end tubes e 1 , e 2 are preferably identical in cross section , it is within the scope of the invention to vary the size , shape and / or configuration such that smaller distal end tubes and / or lumens , or varying types of lumens and distal end tubes may be used for other applications , such as an addition of a third , smaller lumen and corresponding distal end tube for introduction of medication . the assembly according to the second embodiment , in addition to an l 1 & amp ; l 2 distal end opening , may or may not include a plurality of side holes 109 extending through exterior surfaces of the distal end tubes d 1 , to the first lumen 112 . a second set of side holes 110 extending through exterior surfaces of the distal end of tube 105 , to the second lumen 113 . the side holes 109 , 110 provide additional or alternative flow paths . the side holes 109 , 110 can be of various shape , but are typically circular or oval , or of some combination . fig3 illustrates another embodiment of the present invention , where a catheter assembly has at least two lumens . the illustration of two lumens is exemplary , and the scope of the invention encompasses catheters having more than two lumens . the catheter assembly includes first tube t 1 which has a proximal end 101 and a distal end 103 . the catheter assembly includes a second tube t 2 which has a proximal end 104 and a distal end 106 . the fist tube t 1 and the second tube t 2 united ( fused ) at catheter shaft tc as a result of fusion of a portion 104 of first tube t 1 and the 105 of second tube t 2 . the catheter assembly can be provided ( manufactured ) so that the first tube t 1 and the second tube t 2 is fused along a portion extending from the point 107 to the end of both tube 103 , 106 so as to have a common distal end . the assembly according to the third embodiment includes tipping of the distal end of the catheter shaft tc to form a distal catheter tip 120 . the multilumen catheter assembly includes a first lumen 112 and a second lumen 113 extending longitudinally therethrough as illustrated at c 1 . the first and second lumen 112 , 113 are continuous with and through the first and second tube t 1 , t 2 from the distal end 103 , 106 , the catheter shaft tc and first and second extension tube e 1 , e 2 . the first and the second extension tubes e 1 and e 2 lead to a proximal end of the catheter assembly , through which the materials entering and or exiting the patient enter and / or exit the catheter assembly . the words “ proximal ” and “ distal ” refer to directions away from and closer to , respectively , the inserted end of the catheter assembly . the exterior of the catheter shaft tc includes a smooth , rounded without ridges or grooves . as shown in the cross - section c 1 of the catheter shaft tc , the outer surface of the catheter shaft tc is generally rounded in shape ( outer configuration ), c 1 illustrating in cross - section a generally round shaped outer wall , with the first and the second lumens 112 , 113 having a circular cross - section . catheter shaft tc can have various shapes , such as but not limited to circular , semi - circular or oval . also lumen cross section can have various shapes , such as but not limited to circular , semi - circular or oval in the above mentioned embodiments , it is noted that the proximal ends 101 , 104 may occur at different locations in various catheters . it is within the scope of the present invention to incorporate , in the dimensional aspects of length disclosed above , all locations where the proximal ends 101 , 104 could be said to occur in catheters known in the art , disclosed herein , or to be developed . the smooth generally round exterior surface of the catheter shaft tc passes through and remains positioned at a vessel wall insertion site during insertion of the catheter assembly into a patient . a vessel wall seals quite well around the smooth , round exterior surface of the catheter shaft tc , as shown in cross - section c 1 . since the exterior of the catheter shaft tc provides a good seal at the insertion site , the risk of blood loss around the catheter assembly at the insertion site is minimized . the first and the second lumens 112 , 113 are always circular since circular cross sections are most conducive to fluid flow properties . however , other shapes such as d - shaped passageways and / or lumens , oval , triangular , square , elliptical , kidney - bean shaped passageways and / or lumens , or other configurations are also within the scope of the invention . further , while the catheter tubes t 1 , t 2 , the lumens 112 , 113 and the proximal end tubes e 1 , e 2 are preferably identical in cross section , it is within the scope of the invention to vary the size , shape and / or configuration such that smaller distal end tubes and / or lumens , or varying types of lumens and distal end tubes may be used for other applications , such as an addition of a third , smaller lumen and corresponding distal end tube for introduction of medication . a plurality of side holes 109 , 110 extending through exterior surfaces of tubes 102 , 105 , to the first and second lumens 112 , 113 . the side holes 109 , 110 provide additional or alternative flow paths . the side holes 109 , 110 can be of various shape , but are typically circular or oval , or of some combination . a cuff 114 may or may not be located at a point along the catheter shaft tc . cuffs are known in the art and provide a surface onto which internal tissue may adhere to stabilize the catheter assembly within the patient . the catheter assembly according to the various embodiments may be secured to patient skin by a fixation device . the catheter assembly according to the various embodiments may incorporate a hub secured or over molded over point 107 . the present invention further includes methods for making the multilumen catheter assemblies described above . the fusion parameter settings allow the catheter tube either to be releasable joined to allow longitudinally split from each other or non releasable joined . the present invention also provides a method for making a multitube catheter assembly , by fusing two or more tubes together by use of heat sensitive tube slides over the tubes while metallic mandrels are passed through each tube lumen to protect the lumens during fusion . the heat sensitive tube will generate pressure once heat is applied . continual heating will melt / re - shape the catheter tubes inside the heat sensitive tube while the letter will not be affected due to its high melting temperature . after cooling the heat shrink tube is removed around the fused catheter tubes , the metallic mandrels pulled back and the tubes , forming the one catheter tube . at fig4 illustrate the catheter tube t 1 , t 2 cross sectional changes during the fusion process . according to c 5 , the first tube t 1 and the second tube t 2 has a general round outer surface and circular lumen 112 , 113 and a wall 115 , 116 . c 4 illustrates the presence of the heat sensitive tube 117 slides over the first and second tube t 1 , t 2 . the heat sensitive tube 117 contract and generates pressure once heat is applied . continual heating will melt / re - shape the catheter tubes t 1 , t 2 inside the heat sensitive tube 117 while the letter will not be affected due to its high melting temperature . at c 3 , continual heating melt the wall 115 , 116 of the first and second tube t 1 , t 2 . at c 2 , the wall 115 , 116 fuse together forming one wall 111 defining the catheter tube tc around the catheter lumen 112 , 113 . catheter lumens 112 , 113 are protected during fusion process by the presence of a round mandrel with definite size inside each of them . at c 1 , after cooling , the heat sensitive tube 117 is removed around the formed tc . the metallic mandrels are to be pulled back the catheter shaft tube tc is formed with the wall 111 around the catheter lumens 112 , 113 .
multitube catheter and method for making the same are provided . the assembly includes two or more tube fused together to form one catheter tube shaft . each tube has at least one lumen extending longitudinally through the catheter from its distal end to its proximal end . the tubes are fused together by use of heat & amp ; pressure . heat and pressure can be generated by heat sensitive tube slides over a segment of catheter tubes while metallic mandrels are passed through each tube lumen to protect the lumens during fusion . the heat sensitive tube will shrink once heat is applied . the heat sensitive tube will shrink and apply the required pressure over the catheter tubes . continual heating will melt and re - shape the catheter tubes inside the heat sensitive tube while the letter will not be affected due to its high melting temperature . after cooling , the heat sensitive tube is to be removed , the metallic mandrels are pulled back and the tubes forming the united catheter tube . distal end of the united catheter tube can be splited to form split tip , stepped tip or can be tapered tipped . the proximal segment will form catheter extension legs . the pressure applied can also be created by silicon or rubber tube stretched over the catheter tubes , in a mould , by coextrusion , by over molding , through adhesions are other possible methods .