Abstract:
A method of making a multi-lumen catheter includes forming a catheter body including a first lumen and a second lumen, and forming a catheter tip having a first channel terminating distally in a first opening on a first side of the catheter tip, and a second channel terminating distally in a second opening on a second side of the catheter tip opposite of the first side. The first and second openings of the catheter tip extend through an outer wall of the catheter tip to a dividing section. The catheter tip is affixed to the catheter body such that the first channel is aligned with the first lumen and the second channel is aligned with the second lumen.

Description:
PRIORITY 
     This is a continuation of U.S. patent application Ser. No. 10/886,403, filed Jul. 6, 2004, now U.S. Pat. No. 7,485,107, which is a continuation of U.S. patent application Ser. No. 09/429,857, filed Oct. 29, 1999, now U.S. Pat. No. 6,786,884, each of which is incorporated into this application as if fully set forth herein. 
    
    
     BACKGROUND 
     The present invention relates generally to medical devices, and more particularly to an improved tip design for a multi-lumen catheter. 
     Multi-lumen catheters are used for a variety of applications when it is necessary to have two separate fluid pathways. One such application for a multi-lumen catheter is for use in a hemodialysis process. During hemodialysis, a dual-lumen catheter can be employed to simultaneously accommodate opposing blood flow. More specifically, one lumen carries blood from a patient to a dialysis machine where it is processed for the removal of toxins, while the opposing lumen returns the purified blood to the patient. 
     Multi-lumen catheters are well known in the art. An example of such a catheter used for hemodialysis is shown in U.S. Pat. No. 4,808,155 to Mahurkar, which discloses a double lumen catheter including a return lumen and an inlet lumen. The return lumen extends along the entire length of the catheter to an opening at the distal end of the catheter. The inlet lumen is shorter than the return lumen and terminates at an opening substantially displaced from the return opening. The separation of the two openings is designed to prevent the mixing of treated blood with non-treated blood. Problems may result from this design, however. First, the openings may become partially or totally occluded by the vessel wall or by a build up of blood components. Second, due to the pressure of fluid exiting the return lumen, a whipping action can occur, wherein the sharp edges of the tip of the catheter lashes back and forth within the vein of a patient, causing trauma to the inside wall of the vein. This whipping action can also cause clots to form around the outside surface of the catheter, obstructing blood flow to and from the openings. 
     To overcome the problems of the Mahurkar device, Cruz et al. (U.S. Pat. No. 5,571,093) proposed a multi-lumen catheter with a bolus tip, containing a radial passage that forms a port through the side of the bolus. In one embodiment, a first and second lumen are in fluid communication with the port. In another embodiment, the bolus tip contains two ports in the same side, one port providing an opening for the first lumen while the other port provides an opening for the second lumen. In both embodiments, the port nearest to the distal end of the bolus tip is created by removing a piece of the body around greater than 180° of the circumference of the body. According to Cruz et al., this configuration causes the velocity of the fluid passing over the bolus to decrease, thereby limiting the whipping action. However, because the outlets of the first and second lumen are located on the same side of the bolus, the problem of mixing treated and non-treated blood exists. Accordingly, there is a need for a catheter tip configuration that maintains adequate separation of treated and non-treated blood and that reduces the traumatic effects associated with whipping. In addition, there is a need for a catheter tip that will not easily become occluded. 
     It is therefore an object of this invention to provide an improved bolus tip design for a multi-lumen catheter that provides an optimum separation of fluids to be simultaneously injected into and aspirated from a patient&#39;s body. 
     It is a further object of this invention to provide an improved bolus tip design for a multi-lumen catheter that reduces the trauma to the vein of a patient associated with insertion of the catheter and whipping. 
     It is still a further object of this invention to provide an improved bolus tip design for a multi-lumen catheter that will allow the continuous transfer of fluid to a patient despite the presence of obstructions. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides an improved bolus tip design for use in a multi-lumen catheter for the simultaneous injection and withdrawal of fluids to and from a patient. The bolus tip includes an elongate body preferably made of either silicone or polyurethane, having two channels for fluid flow. The edges of the bolus tip are rounded to prevent unnecessary trauma to the patient&#39;s vein which can occur when the device is initially inserted into the patient, as well as when whipping occurs, which results when fluid being released to the body under pressure causes the device to sway violently back and forth within the vein. An interfacing section at a proximal end of the bolus tip is integrated into the multi-lumen catheter so that the lumens of the catheter match the channels of the bolus tip for uninterrupted flow of fluids therethrough. 
     The integrating of the bolus tip and multi-lumen catheter can be accomplished by one of two procedures. In a first integrating procedure, the bolus tip and catheter are glued together. The outer diameter of the bolus tip at the interfacing point is made slightly greater than that of the multi-lumen catheter so that the catheter can slidably be received by the bolus tip. The bolus tip has a restraining ledge near the bottom of the interfacing section for preventing the further advancement of the catheter during integration. In a second integrating procedure, the bolus tip and catheter are joined through an injection molding process, in which the distal end of a formed catheter is inserted into the bolus tip mold and polyurethane is injected to form the bolus tip with the catheter, resulting in common outer diameters and fluid flow channels. 
     The two channels, a first channel and a second channel, of the bolus tip run parallel to each other from the catheter to respective outlets, separated by a dividing section. The two channels are generally used for fluid flow, but in certain embodiments, the second channel can be used to house a guidewire for introduction of the catheter into the patient. This is a preferred method of introduction of the catheter over the use of a sheath because of ease, efficiency, and reduced trauma to the patient. The dividing section, in addition to separating the channels, acts as a stabilizing force for the bolus tip by connecting the interfacing section to the nose section. Moreover, in a preferred embodiment, the dividing section also provides a central channel to house the guidewire. 
     The first channel terminates in a first bolus cavity, which is formed into one side of the bolus tip at a point between the interfacing section and the nose section of the bolus tip. The first bolus cavity extends down to the dividing section in a U-shaped notch, allowing the first channel to be in fluid communication with the surrounding area. The configuration of the first bolus cavity promotes ease of fluid transfer between the bolus tip and the patient, thereby reducing problems associated with the fluid exchange, including whipping and occlusion. Whipping tendency is decreased because the U-shaped configuration effectively slows down the fluid flow. Total occlusion is avoided because even if the surface area of the cavity along the outer diameter of the bolus tip is covered, fluids are still able to enter or exit through the sides of the cavity. 
     The second channel extends beyond the first channel in the direction of the distal end of the bolus tip. The ending point for the second channel can be configured in one of two ways. In one configuration, the second channel stretches from the interfacing section to the nose section of the catheter. An opening is formed in the end of the catheter which is slightly wider than the second channel itself, facilitating the inlet and outlet of fluids. In another configuration, a second bolus cavity is formed in the side directly opposite the first bolus cavity, located longitudinally between the first bolus cavity and the tip of the nose section. This second bolus cavity also extends to the dividing section in a U-shaped notch, allowing the second channel to be in fluid communication with the surrounding area. 
     These and other features and advantages of the present invention will become more apparent to those skilled in the art when taken with reference to the following more detailed description of the preferred embodiments of the invention in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a first embodiment of the present invention. 
         FIG. 2  is a longitudinal sectional view of  FIG. 1 . 
         FIG. 3  is a longitudinal sectional view of a second embodiment of the present invention. 
         FIG. 4  is a transverse sectional view taken along line  4 - 4  of  FIG. 1 . 
         FIG. 5  is a transverse sectional view taken along line  5 - 5  of  FIG. 1 . 
         FIG. 6  is a side view of a third embodiment of the present invention. 
         FIG. 7  is a longitudinal sectional view of  FIG. 6 . 
         FIG. 8  is a transverse sectional view taken along line  8 - 8  of  FIG. 6 . 
         FIG. 9  is a transverse sectional view taken along line  9 - 9  of  FIG. 6 . 
         FIG. 10  is transverse sectional view of an alternate configuration for the third embodiment shown in  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention satisfies the need for an improved bolus tip design for use with multi-lumen catheters. More particularly, the present invention provides an atraumatic tip design that is efficient and effective in transporting fluids to and from a patient. In the detailed description that follows, it should be appreciated that like reference numerals are used to describe like elements illustrated in one or more of the figures. 
     Turning now to  FIG. 1 , a first embodiment of the present invention is illustrated. A side view of bolus tip  100  is shown coupled to catheter  10  at point  20 . A bolus cavity  114  is located in a side of the bolus tip  100  for the entrance or exit of fluids therefrom.  FIG. 2  more elaborately illustrates the inventive concepts of the first embodiment. The bolus tip  100  is oblong and rounded, with a U-shaped portion removed from the bolus tip  100 , creating the bolus cavity  114 . This U-shaped design is beneficial in that it prevents occlusions by providing both top and side access to the channel and limits the tendency of whipping by acting to slow down the passage of fluids. The bolus tip  100  is made of either silicone or polyurethane in the preferred embodiment, but many other materials are possible. 
     In the sectional view shown in  FIG. 2 , the bolus tip  100  includes two basic sections, an interfacing section  105  and a nose section  140 . The interfacing section  105  further consists of a first section  110 , a dividing section  130  and a second section  120 . The first section  110  includes a first body section  116 , which connects the bolus tip  100  to the catheter  10  and defines the outer wall boundary of a first channel  112  from the edge of the catheter  10  to the bolus cavity  114 . The first channel  112  connects to a first lumen  12  of the catheter  10  to form a single contiguous tunnel for uninterrupted flow of fluids therethrough. The first channel  112  terminates at the bolus cavity  114 , which provides an access point for the ingress or egress of fluids. The bolus cavity  114  is created by the absence of a significant portion of the first section  110  down to the dividing section  130 , forming a U-shape when viewed from the side. 
     The dividing section  130  separates the first channel  112  from the second channel  122 , functioning as a stabilizer for bolus tip  100  by preventing internal collapse of the channels and by connecting the interfacing section  105  to the nose section  140 . The second section  120  includes a second body section  126  that has a built-in ledge  128  for adeptly receiving catheter  10 . The second body section  126  defines an outer wall boundary for a second channel  122  from the edge of catheter  10  to a nose tip opening  124  located in a tip portion  142  of the nose section  140 . The tip portion  142  is rounded to lessen the trauma associated with insertion of the catheter and the whipping action of the catheter. The second channel  122  connects with a second lumen  14  of the catheter  10  to provide a smooth transition between the members. The second channel  122  terminates at the nose tip opening  124 , which is in fluid communication with the patient. The nose tip opening  124  provides an access point for ingress or egress of fluids into the second channel  122 . The second channel  122  can also be used to house a guidewire for introduction of the catheter  10  into the patient. While introduction of the catheter  10  is possible through the use of a sheath, guidewire use is preferred because less trauma to the patient occurs and it is a faster more efficient way to introduce the catheter  10 . 
     The bolus tip  100  and catheter  10  are separately extruded and are affixed to one another through a gluing and/or press fit process at point  20 . As seen in  FIGS. 1 and 2 , the gluing process necessitates a slightly larger diameter for the bolus tip  100  to accommodate the catheter  10  at a point  20  where both the first section  110  and the second section  120  of the bolus tip  100  meet the catheter  10 . The first body section  116  incrementally decreases in diameter to match the diameter of the catheter  10  at the bolus cavity  114 . Similarly, the diameter of second body section  126  incrementally decreases to match the diameter of the catheter  10 . The catheter  10  consists of the first lumen  12 , the second lumen  14  and a septum  16 . As described above, both passages flow continuously into their counterparts in bolus tip  100  to form an uninterrupted channel for fluid flow to and from the patient. 
     Turning to  FIG. 3 , a second embodiment of the bolus tip design is shown. A bolus tip  200  is coupled to the catheter  10  at a point  30 , in the same way as explained above with reference to  FIG. 2 . The catheter  10  is fastened to bolus tip  200 , the two being pressed together until the point that the catheter  10  is stopped by a ledge  228 . As in the first embodiment, the diameter of the bolus tip  200  is slightly larger than the catheter  10  at the joining point  30 , but gradually decreases over the length of the bolus tip  200  so that a nose section  240  is the same diameter as the catheter  10 . The bolus tip  200  includes an interfacing section  205  and the nose section  240 . The interfacing section  205  further consists of a first section  210 , a dividing section  230  and a second section  220 . The first section  210  and the dividing section  230  are similar in form and function to the first embodiment, defining a first channel  212  which terminates at a first bolus cavity  214 . As in the first embodiment, the first bolus cavity  214  is an access point for the ingress and egress of fluids to and from the catheter  10 . The second section  220  differs from the first embodiment in that a second interfacing section  226 , together with the dividing section  230  define a second channel  222  which opens into a second bolus cavity  224 , located longitudinally between first bolus cavity  214  and a tip portion  242  of the nose section  240 . As in the first embodiment, the tip portion  242  is rounded for preventing unnecessary trauma to the vein of the patient. The second bolus cavity  224  is created in the same manner as the first bolus cavity  214 , namely by removing a U-shaped portion from the bolus tip  200 . 
       FIG. 4  is a cross-sectional view of the bolus tip  100  taken along line  4 - 4  in  FIG. 1 . The interfacing section  105  is seen encompassing the catheter  10 . The first lumen  12  and the second lumen  14  of the catheter  10  are shown separated by the septum  16 , both lumens being D-shaped in the preferred embodiment. It is possible, however, for these lumens, as well as their accompanying channels of the bolus tip  100 , to take on a variety of different shapes.  FIG. 5  is a cross-sectional view of the bolus tip  100  taken along line  5 - 5  in  FIG. 1 , through the bolus cavity  114 . This view illustrates the D-shape of the second channel  122  defined by the second section  120  and the dividing section  130 . 
     Turning now to  FIG. 6 , a third embodiment of the present invention is shown of a bolus tip  300  attached to a catheter  40 . This embodiment differs from the previous two embodiments in two aspects. First, the bolus tip  300  has a central channel  332  extending through a dividing section  330  for the passage of a guidewire, as shown in  FIG. 7 ; a septum (not shown) of catheter  40  has a central lumen (not shown) that is directly linked to the central channel  332 . Second, the connection between the bolus tip  300  and the catheter  40  is different in that, instead of gluing the catheter  10  into the bolus tip  300 , the two are completely joined through an injection molding process, wherein the distal end of the already formed catheter  40  is placed into the mold for the bolus tip  300  prior to injection. This results in common outer diameters and fluid flow channels for catheter  40  and bolus tip  300 .  FIG. 7  illustrates the bolus tip  300  by showing a longitudinal cross-sectional view of the third embodiment. Like the first two embodiments, the bolus tip  300  includes an interfacing section  305  and a nose section  340 . The interfacing section  305  further consists of a first section  310 , a second section  320  and a dividing section  330 . Similar to the second embodiment shown in  FIG. 3 , a first body section  316  and a second body section  326  define the first and second portions of channels  312  and  322  respectively. The first channel  312  terminates in a first bolus cavity  314 , while the second channel  322  terminates in a second bolus cavity  324  in a configuration similar to that of the second embodiment. The dividing section  330  includes the central channel  332  running throughout the length of the bolus tip  300 , through the rounded nose section  340 . The central channel  332  is sized to accommodate a guidewire for easy insertion of catheter  40  and bolus tip  300  into a targeted area of the patient&#39;s body. 
       FIGS. 8 and 9  show cross-sectional views along lines  8 - 8  and  9 - 9  in  FIG. 6  respectively. The first channel  312  and the second channel  322  are shown with trapezoidal-like shapes, the bases of each trapezoidal channel being partially carved out by the intersection of the dividing section  330 .  FIG. 10  shows an alternate embodiment for a cross section along the line  8 - 8 , wherein channels  412  and  422  are D-shaped, with no alteration to the shape of the channels coming from the dividing section  430 . 
     Many alterations and modifications may be made by those having ordinary skill in the art without departing from the spirit and scope of the present invention. For example, the second bolus cavity is disclosed as being located directly opposite the first bolus cavity. It should be apparent, however, that the inventive concepts described above would be equally applicable to a configuration where the second bolus cavity is located on a side adjacent to the first bolus cavity. Moreover, the words used in this specification to describe the invention and its various embodiments are to be understood not only in the sense of their commonly defined meanings, but to include by special definition in this specification structure, material or acts beyond the scope of the commonly defined meanings. Thus, if an element can be understood in the context of this specification as including more than one meaning, then its use in a claim must be understood as being generic to all possible meanings supported by the specification and by the word itself. The definitions of the words or elements of the following claims are, therefore, defined in this specification to include not only the combination of elements which are literally set forth, but all equivalent structure, material or acts for performing substantially the same function in substantially the same way to obtain substantially the same result.