Abstract:
The invention is of an improved peritoneal dialysis catheter the structure of which permits simultaneous inflow and outflow therapy. The design eliminates angular deviations of conduits to prevent occlusion through biological debris, insures optimal seating and sealing in the abdominal wall, and, to previously proposed designs for similar devices, is possible to manufacture using existing technology and manufacturing techniques.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to medical catheters and to peritoneal dialysis catheters in particular.  
           [0003]    2. Background Information  
           [0004]    The foldable peritoneal dialysis catheter as disclosed in U.S. Pat. No. 5,322,519 (“the Ash catheter”) represented a substantial advance in peritoneal catheter design and technology. However, the design of the ash catheter leaves certain characteristics of the ideal peritoneal dialysis catheter lacking.  
           [0005]    The only feasible embodiments of the Ash catheter invention or those designed for inflow or outflow, but not both. Ash does teach the basic concept of a peritoneal dialysis catheter for continuous use (Column  4 , lines  54  et seq.), in other words, one which includes separate conduits for simultaneous inflow and outflow. However, Ash fails to provide an actual, workable design.  
           [0006]    Ash&#39;s FIG. 4 depicts a proposed design for a continuous use peritoneal catheter, but one which simply cannot be made when existing technology is applied to the silicone material from which such catheters must be made. For example, Ash&#39;s septum  128  must, in order to be operative, form a fluid seal with the inner wall of housing  122 . Even if this were possible to achieve in the manufacturing process (which experts in the silicone extrusion and manufacturing industry indicate it is not), the resulting catheter would be too rigid (because of the added rigidity of such  128 ) to be suitable for implantation. In addition, the T-configuration shown for this embodiment would, in actual application, causes accumulation of biological debris (and ultimately clogging) near the 90 degree bends in the conduits.  
           [0007]    Ash&#39;s alternative continuous dialysis catheter design (shown in Ash&#39;s FIG. 8) is also a non-viable design suggestion. Merely conjoining two parallel conduits (Ash&#39;s “plenum chambers”  146  and  148 ) creates a cross-sectional footprint (other than substantially circular) which is not suitable for passage through, and long-term residence in the abdominal wall because of increased propensity for leakage, bacterial invasion, etc.  
           [0008]    It would well serve those who administer and those who receive peritoneal dialysis to provide a viable design for a continuous use peritoneal dialysis catheter—one which provides all the benefits of the viable embodiments of the Ash single direction flow catheter, but goes farther in satisfying the remaining, unfulfilled objectives for an Ash-like catheter for continuous dialysis use.  
         SUMMARY OF THE INVENTION  
         [0009]    It is an object of the present invention to provide an improved peritoneal dialysis catheter.  
           [0010]    It is another object of the present invention to provide an improved peritoneal dialysis catheter which is suitable for continuous use (allowing simultaneous inflow and outflow).  
           [0011]    It is another object of the present invention to provide an improved peritoneal dialysis catheter which is suitable for continuous use, and which is of a design which can feasiblely be manufactured using available manufacturing technology and methods.  
           [0012]    It is another object of the present invention to provide an improved peritoneal dialysis catheter which is suitable for continuous use, it presents an ideal, circular cross-sectional contour of portions of such catheter as pass through and reside in the abdominal wall of a recipient.  
           [0013]    It is another object of the present invention to provide an improved peritoneal dialysis catheter which is suitable for continuous use, and which is of a design which minimizes the chances of conduit occlusion because of highly angular diversions of the conduits.  
           [0014]    In satisfaction of these and related objects, the present invention provides an improved peritoneal dialysis catheter which, because of seemingly minor, but highly significant modifications from prior art designs, is unique in its manufacturerability and its capacity to serve as continuous use peritoneal dialysis catheter without undue patient complications.  
           [0015]    The peritoneal dialysis catheter design of the present invention, in the preferred embodiments, utilizes linearly mated conduits for that portion of the catheter which passes through the patient&#39;s abdominal wall (the trans-abdominal segment) and which cooperatively defined a substantially circular cross-sectional footprint. This feature provides the optimum cross-sectional footprint for lessening the likelihood of leakage and infection. Also, the present design avoids using a T-joint configuration as the transition from the trans-abdominal wall segment the catheter to the peripheral fluid transport branches which reside within a patient&#39;s abdomen—such a T-joint configuration creating a propensity for clogging near the angular conduit deviations, as well as creating excessive bulk which impedes implantation. Rather, the design of the present invention, because of the nested conduit design which lacks a septum has taught by Ash, is capable of actual manufacture, allows for the aforementioned circular cross-section for the trans-abdominal wall segment, and permits the transition from the trans-abdominal wall segment to the fluid transport branches of the catheter to proceed along a non-angular path. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is an elevational view of a preferred embodiment of the peritoneal dialysis catheter of the present invention.  
         [0017]    [0017]FIG. 2 is an elevational cross-section view of the catheter of FIG. 1 along line C-C of FIG. 1.  
         [0018]    [0018]FIG. 3 is an elevational cross-section view of input conduit  12  shown along line A-A of FIG. 1.  
         [0019]    [0019]FIG. 4 is an elevational cross-section view of output conduit  14  shown along line B-B of FIG. 1.  
         [0020]    [0020]FIG. 5 is an elevational cross-section view of fluid transport branch  22  along line E-E of FIG. 1.  
         [0021]    [0021]FIG. 6 is an elevational cross-section view of fluid transport branch  24  along line F-F of FIG. 1.  
         [0022]    [0022]FIG. 7 is an elevational, partially cut away view of the juncture between input conduit  12  and fluid transport branch  22  bounded by juncture sleeve  28 .  
         [0023]    [0023]FIG. 8 is an elevational cross-section view of FIG. 7 along line J-J.  
         [0024]    [0024]FIG. 9 is a cross-section view of FIG. 7 along line K-K. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0025]    Referring to FIG. 1, a peritoneal catheter of the present invention is identified generally by the reference numeral  10 . Peritoneal catheter  10  comprises, generally, an inflow conduit  12  and an outflow conduit  14 .  
         [0026]    At a proximal divergence point  16 , inflow conduit  12  and outflow conduit  14  are not attached and extend to respective sources of fluids to be infused or receptacles for fluids expelled in the peritoneal dialysis process. At a distal divergence point  18 , inflow conduit  12  and outflow conduit  14  again diverge as they respectively extend toward junctures with fluid transport branches  22  and  24 .  
         [0027]    Between proximal divergence point  16  and distal divergence point  18  is a trans-abdominal segment  20  of catheter  10 . The trans-abdominal segment  20  of catheter  10  is a length throughout which inflow conduit  12  and outflow conduit  14  or conjoined.  
         [0028]    Referring principally to FIGS. 2, 3, and  4 , the respective cross-sectional shapes of inflow conduit  12  and outflow conduit  14 , while they may vary from that shown in the preferred embodiment, should, when mated along the length of trans-abdominal segment  20 , cooperatively define a substantially circular cross-section for both conduits  12  and  14  together. As depicted in FIGS. 2, 3 and  4 , this may be achieved by using cross sectional shapes for inflow conduit  12  and outflow conduit  14  whereby the former is nested within an elongate trough  26  which is formed along the length of the latter (or vice versa).  
         [0029]    Using existing technology in the silicon extrusion field, inflow conduit  12  and outflow conduit  14  are separately extruded in their desired cross-sectional shapes and then bonded along their lengths as correspond to the trans-abdominal section  20  of catheter  10 . Lengths of inflow conduit  12  and outflow conduit  14  outside the boundaries of the trans-abdominal segment  20  are simply left not bonded.  
         [0030]    Because inflow conduit  12  and outflow conduit  14  are wholly separate structures which are merely bonded along the length over which they must cooperatively define an acceptable cross-sectional shape for the entire catheter  10 , there is no need whatsoever for a component which corresponds to T-joint as is used in the Ash catheter and which would introduce the aforementioned problems associated with using such a component and create an undesirably angular path to be followed in the transition from a trans-abdominal segment  20  to the converging fluid transport branches  22  and  24 .  
         [0031]    [0031]FIGS. 5 and 6 depict exemplary cross-sectional structures for fluid transport branches  22  and  24  such that fluid transport branches  22  and  24  fall within the definition of fluted catheter segments as are known to be highly beneficial and avoiding omentum occlusion after implantation. While the cross sectional configuration depicted in FIG. 5 for fluid transport branches  22  and  24  is a very good, if not the preferred configuration, such is only one of many fluted catheter segment configurations which may be incorporated into any embodiment of the present invention, the specific configuration of the fluted segments not being a critical element of the present invention.  
         [0032]    Referring principally to FIGS. 1, 7,  8 , and  9 , distally of distal divergence point  18  inflow conduit  12  and outflow conduit  14  each are mated with their respective fluid transport branches  22  and  24  for use of juncture sleeves  28 . Variations of this juncture scheme to accommodate differing geometries for the inflow or outflow conduits, as well as for the fluid transport branches, will be apparent to persons skilled in the art. In any event, however, the juxtaposition of conduits  12  or  14  and fluid transfer branches  22  or  24  will result in substantially a coaxial arrangement whereby no angular deviation from either conduit and its respective fluid transport branch.  
         [0033]    Implantation of catheter  10  of the present invention is ideally achieved through the same methodology taught by Ash beginning in column 5, line 27 and ending at Column 6, line 8, which portion of said patent (U.S. Pat. No. 5,322,519) is incorporated herein by reference.  
         [0034]    Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limited sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the inventions will become apparent to persons skilled in the art upon the reference to the description of the invention. It is, therefore, contemplated that the appended claims will cover such modifications that fall within the scope of the invention.