Abstract:
Disclosed is a double lumen continuous flow dialysis catheter having contiguous lumens of different lengths, the shorter lumen acting as a blood intake lumen and the longer as a blood return lumen. The catheter is designed to ease insertion into the body without the use of a tearaway sheath and to minimize recirculation flow from the blood return lumen to the blood intake lumen and/or prevent the blood intake lumen from becoming compressed against a vessel or body wall during dialysis.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of International Application No. PCT/US2004/027203, filed on Aug. 20, 2004, and incorporates by reference and claims priority to International Application No. PCT/US2004/027203, filed on Aug. 20, 2004, and U.S. Provisional Patent Application No. 60/496,410, filed on Aug. 20, 2003. 
     
    
     BACKGROUND  
       [0002]     This invention relates to a catheter primarily for use in dialysis and more specifically, to a dialysis catheter having a double lumen, a diverting structure and a temporary stiffener.  
         [0003]     Dialysis is currently performed in two basic ways. First, the conventional way employing two needles, one for removing the blood from the vein or body for processing in a dialysis unit and the other needle for returning processed blood back into the vein or body. In this conventional technique for dialysis, the two needles must be spaced apart a sufficient distance so as to prevent the cleansed blood from re-entering the blood outlet needle and returning to the dialysis unit but must be sufficiently close to each other to prevent the vein from collapsing.  
         [0004]     A second known manner of performing dialysis utilizes a single needle in which blood is both extracted and returned through the same needle. However, single needle dialysis requires an intermittent occlusion machine which is capable of the cyclical operation necessitated by the single lumen needle with bi-directional flow. In addition, single needle dialysis can only operate within limited flow rates and accordingly is not suitable for all patients.  
         [0005]     For repeated dialysis requirements, a method utilizing two long tubes of almost unequal length attached side by side is also known. In general, the tubes are introduced into the jugular vein and remain there for several days, weeks or even months, during which hemodialysis is performed.  
         [0006]     Also known in the art as shown in U.S. Pat. No. 4,134,402 is to provide a double lumen catheter for dialysis capable of achieving blood flow rates comparable to the conventional two needle system while requiring only one puncture.  
         [0007]     Further known in the art are multiple lumen catheters capable of use with a conventional dialysis unit as disclosed in U.S. Pat. Nos. 5,221,255, 5,221,256 and 5,486,159.  
       SUMMARY  
       [0008]     Briefly stated, the present invention consists of a single catheter having two contiguous lumens or conduits, one slightly longer than the other, containing a temporary stiffening member, designed to ease insertion of the catheter into the body without the use of a tearaway sheath. The catheter is generally inserted into the vein or body in the direction of blood flow. The shorter lumen then serves as a blood intake lumen and the longer lumen, the end of which is positioned away from the end of the shorter lumen in the direction of blood flow, serves as a blood return lumen. A distally located diverting structure is also provided to ensure that cleansed blood returning to the vein or body will not re-enter the intake lumen, but rather will be carried “downstream”. The diverting structure also functions to prevent the blood intake lumen from becoming compressed against the vessel or body wall during dialysis. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is an illustration of a double lumen catheter of the present invention;  
         [0010]      FIG. 2  is a cross section of the double lumen catheter of  FIG. 1 ;  
         [0011]      FIG. 3  is an illustration of the front distal section of the double lumen catheter of  FIG. 1 ;  
         [0012]      FIG. 4  is an illustration of the rear proximal section of the double lumen catheter of  FIG. 1 ;  
         [0013]      FIG. 5  is an illustration of another embodiment of the front distal section of a double lumen catheter of the present invention;  
         [0014]      FIG. 6  is an illustration of a further embodiment of the front distal section of a double lumen catheter of the present invention;  
         [0015]      FIG. 7  is an illustration of still another embodiment of the front distal section of a double lumen catheter of the present invention;  
         [0016]      FIG. 8  is an illustration of another embodiment of the distal tip section of a double lumen catheter of the present invention;  
         [0017]      FIG. 9  is an illustration of still another embodiment of the distal tip section of a double lumen catheter of the present invention; and  
         [0018]      FIG. 10  is a schematic showing blood flow during dialysis. 
     
    
     DETAILED DESCRIPTION  
       [0019]     Referring to  FIGS. 1 and 2 , it can be seen that the present invention consists of a single catheter  1  having intake lumen  2  and return lumen  3  terminating in blood intake aperture  8  and blood return aperture  9 , respectively. The term “catheter” as used in this specification includes rigid metal devices such as needles as well as flexible plastic devices such as cannula. As illustrated in  FIGS. 1, 3 ,  5  and  7 , blood return aperture  9  at the end of return lumen  3  extends distally beyond blood intake aperture  8  at the end of intake lumen  2  a sufficient distance to prevent mixing of the blood during the hemodialysis operation. The precise distance by which return lumen  3  extends distally beyond intake lumen  2  is determined by the rate of blood flow, the angle of entrance of the double lumen, and the size of the vein or vessel in which the blood is flowing. Strictly by way of example, for an average vessel, (e.g., a surgically constructed blood vessel with rapid blood flow rates) having a diameter of ½ inch and processing blood at approximately 500 cubic centimeters per minute, the separation distance “d” (see  FIG. 3 ) between return lumen  3  and intake lumen  2  would be approximately ¼ inch. This separation could be as large as ¾ inch or even larger in some circumstances. In a preferred embodiment, the distal end of each lumen may be provided with beveled edges  4  and  5  sloping outwardly and away from the distal catheter tip to promote ease of insertion of catheter  1 .  
         [0020]     A diverting structure  30  extending outward from septum wall  6  and located distally of blood intake aperture  8  as shown in  FIG. 3  can also be provided to function as a flow diverter to reduce access recirculation and to raise fluid pressure in the vicinity of blood intake aperture  8 . Diverting structure  30  can also function to prevent intake lumen  2  from becoming compressed against the vessel or body wall during dialysis. Diverting structure  30  can be any shape or form so long as it diverts recirculation flow from blood return aperture  9  away from blood intake aperture  8  and/or prevents intake intake lumen  2  from becoming compressed against the vessel or body wall during dialysis. As shown in  FIGS. 1 and 3 , diverting structure  30  is in the form of a frustum and completes a phantom outline of intake lumen  2  projected in a proximal direction from blood intake aperture  8 . Further, as depicted in  FIGS. 1, 3 ,  5  and  7 , diverting structure  30  has a slanted face opposed to recirculation flow to minimize catheter insertion trauma. Preferably, diverting structure  30  is made from a material of heavier construction than that which forms outer wall  7  of catheter  1 , such that it also functions as a tissue dilator to ease insertion of catheter  1 . Alternatively, diverting structure  30  can be made of the same material as outer wall  7 .  
         [0021]     Referring to  FIG. 2 , it can be seen that in the region where the lumens are contiguous, the lumens are separated by septum wall  6  such that intake lumen  2  and return lumen  3  are each of “D” shaped cross section. At least a portion of return lumen  3  that extends distally beyond intake lumen  2  is preferably of circular cross section ( FIG. 9 ). Septum wall  6  can be relatively thin construction inasmuch as its only function is to separate the blood return conduit  8  from the blood intake conduit  9 . Outer wall  7 , in contrast, must serve as a supporting wall and accordingly may be thicker than septum wall  6 .  
         [0022]     Referring to  FIG. 10 , the actual operation will be described with reference to a double lumen catheter constructed in accordance with the present invention. The double lumen catheter  1  is inserted into the vein or body  10  in the direction of blood flow. The noninserted ends of the lumens are connected to a dialysis unit  11 . This connection can be accomplished by separating contiguous lumens  2  and  3  into two noncontiguous connector tubes  12  and  13  ( FIG. 1 ) of circular cross section with standard luer ends so that conventional coupling members may be utilized. The point of separation can be included in a housing  21  to form a conventional hub (see  FIGS. 1 and 4 ). With dialysis unit  11  in operation, blood flows from the vein or body into intake lumen  2  through connector tube  12  to dialysis unit  11  where blood is processed. The blood is then returned to the vein or body through connector tube  13  and out of return lumen  3 . The distal tip of catheter  1  can also include one or more side openings or ports  27  formed through outer wall  7  in fluid communication with return lumen  3  ( FIG. 3 ), also functioning to return blood to the patient&#39;s body. The returning blood enters the vein or body at a point displaced some distance away from the point where blood enters intake lumen and in the direction of blood flow in the vein or body. The blood flow through the body or vein then carries this processed blood away from intake lumen  2 . As shown in  FIGS. 1 and 4 , catheter  1  can be provided with standard hardware such as rotatable suture ring  22  and fabric (e.g., polyester felt) cuff  23 , while connector tubes  12  and  13  can be provided with standard hardware such as tube clamps  2 - 4 , printed (e.g., product name, priming volume, etc.) ID tags on hubs  25  and luer caps  26 , the use of such hardware being known in the art.  
         [0023]     In order to aid in insertion of catheter  1 , usually by the Seldinger technique, and navigation through small vessels, a stiffening member  20  ( FIGS. 1 and 3 ) may be provided in conjunction with beveled edges  4  and  5  and diverting structure  30 . Stiffening member  20  is preferably inserted into the proximal end of connector tube  13  connected to return lumen  3 . Once positioned, the distal end of stiffening member  20  extends distally of blood return aperture  8  at the distal tip of catheter  1 . A luer lock  27  is provided at the proximal end of stiffening member  20  to secure it to threads  28  at the proximal end of connector tube  13  during insertion of catheter  1 . Stiffening member  20  preferably has an internal lumen  31  extending therethrough for receiving a guidewire for proper placement of catheter  1 . Prior to operation of dialysis unit  11 , luer lock  27  is unscrewed from proximal threads  28  of connector tube  14 , allowing removal of stiffening member  20  from catheter  1 .  
         [0024]     From the foregoing, the present invention has been sufficiently described to enable others skilled in the art, by applying current knowledge, to adapt the same for varying conditions of use without departing from the essential items of novelty involved, which are intended to be defined and secured by claims to this application. Some of those adaptions are shown in the additional embodiments depicted in  FIGS. 5, 6 ,  7 ,  8  and  9 .