Abstract:
A multiple tube catheter, such as a hemo-dialysis catheter, has first and second tubes which are attached to each other over a zone by one or more longitudinally extending wires which joins the two tubes over that zone. When a catheter is implanted in the patient, the attached zone is within the patient so that the catheter cannot be removed or advanced. When the catheter is to be removed, the longitudinally extending wire or wires are pulled proximally out of the tubes involved so that the two tubes can be separated and individually removed. A flexible separating prong within the patient and proximal of the zone holds the tubes apart to further assure that the catheter cannot be moved.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates in general to a device and method for retaining a catheter in a patient and more particularly to the retention of a dual tube hemo-dialysis catheter.  
         DESCRIPTION OF PRIOR ART  
         [0002]    Dual tube hemo-dialysis catheters are used to provide long term access to the venous system. The catheter contains two lumens. One lumen for withdrawal, and one lumen for return blood flow. Hemo-dialysis filtration machines are connected to the catheter at regular intervals such as every other day. The patient&#39;s blood is removed, filtered, and returned to the patient. A catheter of this design is described by Ash et al. in U.S. Pat. No. 5,947,953. These catheters must be fixed to the patient to prevent the catheter from pulling out or advancing into the patient. The most common method is to tunnel the catheter from the point of venous access towards a remote location where the catheter is brought out of the skin. This tunnel may be from 5-20 cm long. A Dacron cuff attached to the catheter shaft is located within the tunnel. The cuff provides a porous area, which the patient&#39;s tissue grows into, providing an anchoring means. The cuff method is described by Martin et al. in U.S. Pat. No. 5,053,023. The catheter also may be sutured to the patient at the exit site by a “purse string” suturing technique.  
           [0003]    Another method of fixing a catheter to the patient to prevent pulling out is to provide a bifurcation which is buried in the subcutaneous tissue. The bifurcate is located just outside of the catheters entrance to the vein. This design is described by Schon et al., in U.S. Pat. No. 5,718,692. The Schon catheter contains two tubes brought together to form a bifurcation. The proximal ends of the tube are split apart and are tunneled separately to a remote location where they are brought through the skin surface. The tissue between the proximal tube legs forms an anchor. If the catheter is pulled on, it cannot come out without pulling through the tissue. The catheter cannot advance due to the hub that joins the two tubes. This method provides better catheter retention than the tunneled and cuffed designs.  
         PROBLEMS WITH PRIOR ART  
         [0004]    When it is desired to remove these catheters, which may be after a period of two years in place, both of the above discussed methods have their downfalls. In both cases, it is necessary to perform minor surgery to loosen the catheter. The tunneled and cuffed catheters require the cuff to be transected from the surrounding tissue. The bifurcated design requires the site above the bifurcation to be opened, the tissue carefully picked away from the catheter and the catheter to be removed in the reverse method from its installation. This is time consuming and dangerous. If the catheter is inadvertently cut, it can easily break during removal.  
         OBJECTS  
         [0005]    Accordingly, it is a major object of this invention to provide a multiple tube catheter design, of which a hemo-dialysis catheter is a prominent example, wherein the catheter design provides an enhanced trade-off of effective anchoring in the patient with ease of removal by a doctor.  
           [0006]    It is a related purpose of this invention to provide this ease of removal without requiring surgery to loosen the catheter for the purpose of removing the catheter.  
           [0007]    It is a further related object of this invention to provide this improved multiple tube catheter in a design which readily adapts to currently employed techniques for catheter insertion.  
           [0008]    It is a further related object of this invention to provide the above objects in a fashion that avoids substantial increased costs in product or procedure.  
           [0009]    It is a further related object of this invention to provide the above objects in a device that does not require the cutting or dissection of tissue to remove the catheter and thus reduces the trauma and discomfort to the patient.  
         BRIEF DESCRIPTION  
         [0010]    In brief, a multiple tube catheter is assembled so that in a zone of the catheter near the mid-point of the tubes, the tubes are longitudinally joined together. Along this zone, the sidewall of one tube is connected to the sidewall of the other. The attachment is achieved by a thread which in a preferred form is a wire. The wire attaches the two tubes together by a technique analogous to that of sewing or stapling or otherwise having the wire or thread extend between the sidewalls of the two tubes.  
           [0011]    The proximal end of the thread or wire extends within the sidewall of one of the tubes to a point outside of the patient. Access can be had to the proximal end of the wire by the medical professional who can pull the wire free from the two tubes that are connected together by the wire. After the wire has been pulled free, the two tubes can be individually removed from the patient. This procedure requires little or no surgical removal or cutting of tissue.  
           [0012]    In a preferred embodiment, the two tubes have adjacent flat surfaces and two threads or wires are used in parallel. In that preferred embodiment, a separating prong, slightly proximal of the attachment zone extends outwardly from the surface of one of the tubes to engage the surface of the other tube to force the tubes to diverge away from one another proximal to said zone. This assures that there is a predetermined bifurcation of the tubes within the patient&#39;s body thereby assuring that the tubes are adequately affixed and anchored in the patient and cannot be accidentally advanced or retracted. Growth of bodily tissues into the space between the tubes and the prong provides further anchoring.  
           [0013]    Definition  
           [0014]    In preferred embodiments, a stainless steel surgical wire having a diameter of approximately 10 mils (0.010 inches) is used. However, elements other than a metallic wire can be used including, for example, a surgical suture.  
           [0015]    Accordingly, it should be understood that in the claims, the term “wire” is used to cover not only the preferred metal wire but also whatever other sutures or threads or the like might be employed in the same or comparable geometric structures to hold the two tubes together in use and by withdrawal to permit parting of the two tubes when use is over.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 schematically illustrates the positioning of a two tube hemo-dialysis catheter in the jugular vein. In FIG. 1, the tubes are brought exterior of the patient at points A. The two tubes are connected at a zone B.  
         [0017]    [0017]FIG. 2 is a perspective illustration of the invention showing the two tubes  10 ,  12  of the catheter which are in full contact with one another at a zone  14 . A separating prong  16  is shown proximal of that zone.  
         [0018]    [0018]FIG. 3 is a perspective illustration of a first embodiment of this invention in which a center segment is shown in longitudinal section. FIG. 3 shows a wire  26  contained in the sidewall of the first tube  22 , the wire being stitched into the sidewall of the second tube  20  in the area  24  where the two tubes are adjacent and stitched back into the sidewall of the first tube. FIG. 3 includes an expanded view of a small proximal segment of the sidewall of the tube  22  to more clearly show where the distal end of the wire  26  terminates within the sidewall; which is at a location exterior of the patient.  
         [0019]    [0019]FIG. 4 illustrates the center segment of the FIG. 3 embodiment on a larger scale. FIG. 4 is a longitudinal sectional view and more clearly shows the wire  26  being stitched between the sidewalls of the two tubes  20 ,  22  and also shows the wire  22  extending through the end of the separating prong  28 .  
         [0020]    [0020]FIG. 4A is a cross-sectional view along the plane A-A of FIG. 4 and shows that two separate parallel wires  26  are employed. FIG. 4A is a cross-section through the separating prong  28  and shows that the wires are passed through the prong.  
         [0021]    [0021]FIG. 4B is a cross-sectional view along the surface B-B of FIG. 2 and illustrates the stitching of the upper tube  20  to the lower tube  22  by the two wires  26 .  
         [0022]    [0022]FIG. 4C is a cross-sectional view of an alternative design separating prong  28  along plane A-A. FIG. 4C shows two wires  29  which reinforce the separating prong.  
         [0023]    [0023]FIG. 5 illustrates a second embodiment of the invention. FIG. 5 is a longitudinal sectional view showing a wire  36  extending through a dove tail juncture  34  of the two tubes  30 ,  32 .  
         [0024]    [0024]FIG. 5A is a cross-sectional view along the plane A-A of FIG. 5 and illustrates an arrangement at that plane which is the same as that of the FIG. 4 embodiment.  
         [0025]    [0025]FIG. 5B is a cross-sectional view along the plane B-B of FIG. 5 illustrating the two wires  36  that extend through the dove tail joining of the two tubes.  
         [0026]    [0026]FIG. 6 is a longitudinal sectional view showing a third embodiment of this invention to which the two tubes  40 ,  42  are joined along a longitudinal lap joint  44 . A single wire  46  is used to stitch the two tubes together.  
         [0027]    [0027]FIG. 6A is a cross-section through the plane A-A of FIG. 6. This cross-section shows the separating prong  48  and illustrates that only one wire  46  is employed in this embodiment.  
         [0028]    [0028]FIG. 6B is a cross-section along the surface B-B of FIG. 6 illustrating how the wire  46  that joins the two tubes together is threaded through the lap joint  44 .  
         [0029]    [0029]FIG. 7 is a longitudinal cross-sectional view of a fourth embodiment in which a suture  56  is used to stitch two tubes  50 ,  52  together at the zone  54  where they are adjacent to one another.  
         [0030]    [0030]FIG. 8 is a longitudinal cross-sectional view of a fifth embodiment, similar to the fourth embodiment, where a suture  66  is employed in a fashion slightly alternate to that of FIG. 5 to stitch the two tubes  60 ,  62  together at the zone  64  where they abut one another.  
         [0031]    [0031]FIG. 9 is a longitudinal cross-sectional view of a sixth embodiment which employs a loop and pin method of coupling the wires  76 ,  78  in the sidewalls of the two tubes  70 ,  72  at the zone of juncture  74 .  
         [0032]    [0032]FIG. 9A is a cross-sectional view along the plane A-A of FIG. 9 and shows the wire  78  passing through an end of the separating prong  80 .  
         [0033]    [0033]FIG. 9B is a cross-sectional view along the surface B-B of FIG. 9 and shows a loop  82  which is attached to the loop wire  76  and loops around the anchor wire  78 .  
         [0034]    [0034]FIG. 10 is a somewhat fanciful transparent perspective view of the FIG. 9 embodiment to more clearly illustrate the loop and pin arrangement of coupling wires  76 ,  78  in the sidewalls of the two tubes  70 ,  72 .  
         [0035]    [0035]FIG. 11 illustrates what happens when the anchor wire  78  in the FIG. 9 embodiment is removed thereby uncoupling the anchor wire  78  from the loops  82  of the loop wire  76  so that the two tubes  70 ,  72  are no longer joined and can be removed from the patient.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0036]    [0036]FIG. 1 shows a first tube  4  and second tube  5  of a dual tube catheter placed in relative position in the jugular vein  6  of a patient. The two tubes  4 ,  5  emerge from the patient at the points A.  
         [0037]    As is known in the art, various fittings  7 ,  8  are shown. The fittings  8  are used to connect the catheter to the rest of the dialysis processing system. Blood flow through the vein  6  is in a downward direction. The lumen in tube  4  is the return lumen and the lumen in tube  5  is the aspiration lumen. The technique of implanting this type of catheter is well known in the art and one technique is described in the Schon U.S. Pat. No. 5,718,692.  
         [0038]    [0038]FIG. 2 illustrates the catheter device of this invention generically in which a first tube  10  and a second tube  12  are joined together at a zone  14  by one of the techniques described herein. A separating prong  16  is positioned proximal of the zone  14  assuring an appropriate separation of the two tubes  10 ,  12 .  
         [0039]    The embodiment shown in FIGS. 3 and 4 illustrates a first tube  20  and a second tube  22  joined together at a zone  24  by wires  26 . FIGS. 3 and 4 show one of the two wires  26 . Both of the wires  26  can be seen in the cross-sectional views of FIG. 4A and FIG. 4B. Each of the wires  26  extends within a proximal portion of the sidewall of the tube  22 . Each wire  26  is threaded into the sidewall of the tube  20  and then back into the sidewall of the tube  22 . In this fashion, the two tubes  20 ,  22  are held together by the two wires  26 . FIG. 4C illustrates an alternative design prong  28  which is reinforced by two wires  29 .  
         [0040]    When the catheter is to be removed, access is had to the wires  26  at the proximal ends of the tubes  20 ,  22 . The tube  22  is cut at the area  27  (see the expanded element in FIG. 3) so that access can be had to the proximal end of each wire  26 . The wires  26  are pulled out of the tubes  20 ,  22  and must be pulled proximal of the opening  22 R in the end of the separator prong  28 . Once that has been done, the two tubes can be separately removed without requiring cutting a patient&#39;s tissue.  
         [0041]    The separator prong  28  is a relatively thin flexible prong which will readily flex during removal without causing significant tissue trauma. It has an end which fits into recess  22 R. The prong may be reinforced with metal to prevent tearing of the polyurethane.  
         [0042]    As may be seen in FIG. 4B, the two tubes  20  and  22  are formed so that at the zone  24 , they have flat surfaces which abut against one another.  
         [0043]    As may be seen in FIGS. 2 and 4, the “bread-loaf” or tunnel like cross-section for the tubes  20  and  22  is maintained some distance proximal of the zone  24 . The tubes  20 ,  22  transition to the usual circular cross-sections distal of the zone  24 .  
         [0044]    The separator prong  28  extends into the wall of the tube  22  at the recess  22 R. The end of the prong  28  has two openings through which the wires  26  pass. This aids in maintaining rigidity for the prong  28  when the catheter is in use. The wires  26  have to be pulled proximally by at least enough to clear the prong  28  in order for the tubes  20 ,  22  to be fully separated.  
         [0045]    [0045]FIG. 5 illustrates a second embodiment of the invention in which the two tubes  30 ,  32  are adjacent to one another along a zone  34  that provides a dove tail engagement between the two tubes. In this embodiment, the joining wires  36  extends through the teeth of both crenellated sections of the dove tail joint  34 . The relatively thin flexible prong  38  extends from the wall of the tube  30  and has an end which fits into a recess in the wall of the tube  32 . As in other embodiments, the joining wires  36  extend through openings in the end of the prong  38 . The removal of the wires  36  and the separation of the tubes  30  and  32  is the same as in the embodiment of FIGS. 3 and 4.  
         [0046]    The FIG. 6 embodiment is similar to the other embodiments in that there are two tubes  40 ,  42  having flat surfaces adjacent to one another along a zone  44  and having a separating prong  48 . The key distinction in FIG. 6 is that the adjacent surface  44  is a longitudinal lap joint and there is only a single joining wire  46 . The wire  46  is threaded between the two portions of the lap joint  44 , as shown in FIG. 6B, in a fashion that means the wire  46  is, in this embodiment, not within a single longitudinal plane. The manner in which the wire  46  is threaded from the upper tube  40  into the lower tube  42  along the surface B-B is mirrored by the manner in which it is threaded from the lower tube  42  into the upper tube  40  at a position  49  proximal of the surface B-B.  
         [0047]    [0047]FIGS. 7 and 8 indicate two other embodiments in which suture material capable of being used for surgical stitching is used. In FIG. 7, the suture  56  extends through the sidewall of the lower tube  52  to the zone  54  where the two tubes are adjacent to one another. At point  54 A, the suture is threaded into the sidewall of the upper tube  50  to return proximally within the sidewall of the upper tube  50  until it exits at the point  54 B. It passes within the sidewall of the lower tube  52 , up through the prong  58  and then proximally through the sidewall of the upper tube  50 .  
         [0048]    The FIG. 8 embodiment is very similar to the FIG. 7 embodiment in which the upper tube  60  and lower tube  62  are joined together at the adjacent surface  64  by a suture  62  that doubles back within the wall of the upper tube  60 ; the one having the prong  68 .  
         [0049]    [0049]FIG. 9 illustrates a sixth embodiment in which first and second tubes  70 ,  72  are deployed adjacent to one another along flat faces  74 . A first wire  76 , called herein a loop wire, is contained in the wall of the tube  72 . A second wire  78 , called herein an anchor wire is contained in the wall of the other tube  70 .  
         [0050]    As may best be seen in FIG. 10, when the catheter is in use, the anchor wire  78  extends through two loops  82  which in turn are soldered to the loop wire  76 . This connection holds the two tubes  70 ,  72  together because the wires  76 ,  78  are contained within the sidewalls of the tubes  70 ,  72 .  
         [0051]    When it is desired to remove the tubes from the patient, the two tubes are separated to facilitate such removal. The anchor wire  78 , as illustrated in FIG. 11, is accessed by a medical professional and withdrawn from the tube  70 . This disconnects the anchor wire  78  from the loops  82  and the two tubes  70 ,  72  can be separated and handled individually.  
         [0052]    It might be noted, that the distal portion of the two tubes in each embodiment is circular in cross-section. To assure that the two tubes are adjacent to one another along a flat surface, the two tubes are formed to have a bread-loaf or tunnel-like cross-section in the zone of contact.  
         [0053]    Numerous embodiments of this invention have been disclosed in order to illustrate the scope of the inventive concept. However, one skilled in the art can apply this concept to other embodiments.  
         [0054]    For example, although it is clearly preferred that the tubes be adjacent along a flat surface, the inventive concept can be employed with two tubes in contact along a circular cross section and thus adjacent only along a line. Such an embodiment might require that the coupling wire or thread be exposed when extending from one tube to the adjacent tube.  
         [0055]    In most embodiments, the preferred format is to have two wires or threads connecting the adjacent tubes. However, a single wire or thread can be used, although at the present time, such is not preferred in most embodiments.  
         [0056]    In all embodiments, it is preferred as shown in FIG. 3, that the proximal ends of the wire are sealed into the catheter so that when the tubes are to be removed, the proximal ends of the tubes are cut at an appropriate point and access can be had to the wire to pull the wire free so that the tubes can be separated. This proximal sealing of the wire can be done after the wire has been threaded into the tubes.  
         [0057]    Plastic tubes of the sort depicted in the various embodiments can be readily molded with the lumen depicted and with the longitudinal openings of the sidewalls for receipt of the wire. The wire is typically assembled in the two tubes by being passed through a longitudinal lumen within the sidewall of one tube and threaded into a similar lumen in the other tube. The wire and tubes are flexible enough so that this threading can be readily achieved.  
         [0058]    In one typical embodiment, the following parameters are employed. The tubes are made of a polyurethane material and have a diameter of 120 mils and a sidewall thickness of 20 mils. The wire is spring temper stainless steel, Teflon coated. The wire ends are slightly tapered to create a stiffness transition. The longitudinal sidewall lumens to receive the wire are approximately 15 mils; enough to provide a very easy slip fit relationship with a 10 mil wire. The prong is 50 mils thick, by 70 mils wide and extends for a length of approximately 200 mils.