Abstract:
A catheter assembly, includes a catheter body, a tubular structure and a stabilizing cuff around a longitudinal length of the tubular structure. The tubular structure may be affixed to an exterior surface of the catheter body, and may include a tapered outer surface at a first terminal end of the tubular structure. The tapered outer surface may have a first outer diameter at the first terminal end of the tubular structure and a second outer diameter greater than the first outer diameter at a terminal end of the tapered outer surface opposite the first terminal end. The tubular structure may have a third outer diameter greater than the first outer diameter at a second terminal end of the tubular structure opposite the first terminal end.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 13/355,264, now U.S. Pat. No. 8,636,700, which is a continuation of U.S. patent application Ser. No. 11/368,953, filed Mar. 6, 2006, now U.S. Pat. No. 8,100,863, which claims priority to U.S. Provisional Application No. 60/658,556, filed Mar. 4, 2005, each of which is incorporated by reference in its entirety into this application. 
    
    
     BACKGROUND 
     Over the years, various apparatuses and devices have been developed for the purpose of introducing and removing fluids from bodies, such as the human body. Examples of such devices include catheters, shunts, drainage tubes, and other tubular medical devices as known in the art, broadly referred to hereafter as “catheters.” Such catheters may be positioned in various locations within a body and, once in place, may be anchored by a stabilizing device. 
     One example of a conventional catheter stabilizing device is a tissue-ingrowth cuff. Tissue-ingrowth cuffs are typically made of a biocompatible fabric, such as polyester, and are typically attached to the outer surface of a catheter or cannula by an adhesive. In many conventional catheters, the cuff is positioned on the catheter such that when the distal portion of the catheter is fully inserted into the body, the cuff is located in subcutaneous tissue, such as a subcutaneous tunnel. A subcutaneous tunnel such as this can be formed by a tunneling tool, such as a trocar, either before or after inserting the distal end of the catheter into a bodily cavity, duct, vessel, or the like. The proximal portion of the catheter having the cuff may then be drawn through the tunnel by the tool while the tool passes through the subcutaneous tissue. In many conventional catheters, an adhesive is applied to the cuff fabric to matte the fabric in an attempt to reduce the amount of force needed to tunnel the catheter. The stabilizing cuff is also typically sized such that upon completion of the catheterization procedure, the cuff fits snugly in the tunnel or other area. 
     Upon completion of the catheterization procedure, surrounding tissue in the body grows into the biocompatible fabric of the cuff to further stabilize the catheter in the catheterized location. In addition to stabilizing the catheter, the ingrown tissue helps to seal off the catheterized location and subcutaneous tunnel from foreign bodies, which may also prevent patient infection. Ingrown tissue may also prevent blood from exiting or pooling around the catheter near the exit site. 
     Although conventional fabric cuffs are inexpensive to make and are generally effective at stabilizing a catheter, difficulty remains in inserting and removing such cuffs into/from a patient. Specifically, because adhesive is used to affix conventional cuffs to the catheter, the ultimate size and profile of the cuff structure (and catheter assembly) may be adversely increased based on the amount and thickness of the adhesive used, which may vary. The integrity of conventional cuff structures is also at least partially dependent on, and may be weakened by, the adhesive bond formed between the cuff structure and the catheter. In addition, the adhesive used to matte the cuff fabric may impede tissue ingrowth or result in a rigid, inflexible cuff structure. 
     Accordingly, there is a need for a robust stabilizing device that improves upon the prior art. There is also need for improved methods of manufacturing cuff structures. 
     SUMMARY 
     According to at least one embodiment, a catheter assembly may comprise a catheter including an inner surface defining one or more elongated lumens therein, a tubular structure affixed to an exterior surface of the catheter, and a stabilizing cuff affixed to, and at least partially embedded within, the tubular structure. In certain embodiments, the tubular structure includes at least one tapered surface extending from an end of the tubular structure to an exterior surface of the catheter. The stabilizing cuff may also be positioned substantially within an annular recess defined in the tubular structure. The catheter and tubular structure may comprise at least one thermoplastic polyurethane resin. In addition, at least one of the thermoplastic polyurethane resins utilized in the catheter may be identical to a thermoplastic polyurethane resin utilized in the tubular structure. 
     In at least one embodiment, the exterior surface of the tubular structure may be at least partially conical in shape. In addition, the tubular structure may be configured to initially snugly fit around the catheter shaft (i.e., an inner diameter of the tubular structure may be configured to initially snugly fit around an exterior surface of the catheter shaft). The tapered surface of the tubular structure may also be configured to exhibit a length of between about 1 to about 3 centimeters. 
     According to at least one exemplary embodiment, a method of forming a catheter assembly may comprise providing a catheter, positioning a tubular structure about the catheter, positioning a stabilizing cuff near the tubular structure, and shaping the tubular structure to form a tapered surface extending from an exterior surface of the catheter. The method may also comprise affixing the stabilizing cuff to the tubular structure and embedding at least a portion of the stabilizing cuff within the tubular structure. In addition, the tubular structure may be shaped by exceeding a transition temperature (e.g., a melting, softening or glass transition temperature) of the tubular structure. 
     In certain embodiments, the method may comprise radially biasing the stabilizing cuff toward the catheter while exceeding a transition temperature of the tubular structure. The method may also comprise positioning a temporary sleeve about the tubular structure prior to shaping the tubular structure. In addition, the tubular structure may be preformed to include at least one tapered end prior to positioning the tubular structure about the catheter. An adhesion-resistant coating may also be applied to the tubular structure prior to shaping the tubular structure. 
     Features from any of the above-mentioned embodiments may be used in combination with one another in accordance with the general principles described herein. These and other embodiments, features and advantages will be more fully understood upon reading the following detailed description in conjunction with the accompanying drawings and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate a number of exemplary embodiments and are a part of the specification. Together with the following description, these drawings demonstrate and explain the principles of the instant disclosure. 
         FIGS. 1-3  illustrate an exemplary method of manufacturing a catheter assembly; 
         FIG. 4  is a partial schematic cross-sectional view of a catheter assembly according to at least one embodiment; 
         FIG. 5  is a perspective view of an exemplary catheter system comprising a catheter assembly according to at least one embodiment; 
         FIG. 6  is a cross-sectional view of the catheter assembly illustrated in  FIG. 4 , taken along line A-A; 
         FIG. 7  is a cross-sectional view of an additional embodiment of a catheter assembly; 
         FIG. 8  is a cross-sectional view of an additional embodiment of a catheter assembly; 
         FIGS. 9-11  illustrate an additional exemplary method of manufacturing a catheter assembly; 
         FIG. 12  is a partial schematic cross-sectional view of an additional embodiment of a catheter assembly; and 
         FIG. 13  is a partial schematic cross-sectional view of a further embodiment of a catheter assembly. 
     
    
    
     Throughout the drawings, identical reference characters and descriptions indicate similar, but not necessarily identical, elements. While the exemplary embodiments described herein are susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, one of skill in the art will understand that the exemplary embodiments described herein are not intended to be limited to the particular forms disclosed. Rather, the instant disclosure covers all modifications, equivalents, and alternatives falling within the scope defined by the appended claims. 
     DETAILED DESCRIPTION 
       FIGS. 1-3  illustrate, in schematic cross-sectional views, an exemplary method of manufacturing a catheter assembly. As seen in  FIG. 1 , in at least one embodiment a tubular structure  12  is slid over, or positioned generally about, the exterior surface of a catheter  10 . In certain embodiments, catheter  10  defines an elongated lumen  18  ( FIG. 6 ). Catheter  10  generally represents any catheter or cannula capable of introducing or removing fluid from a body, such as a human body. For example, catheter  10  may be a single or multi-lumen catheter, a shunt or drainage tube, or the like intended for permanent, semi-permanent, or temporary placement. Catheter  10  may also comprise any catheter or cannula used in connection with infusion, cardiovascular access, renal treatment, hemodialysis, hemodynamic monitoring, parenteral nutrition, peritoneal dialysis, oncologic treatment, or any other function such as simultaneous aspiration and infusion, without limitation. 
     Catheter  10  and/or tubular structure  12  may comprise any material exhibiting suitable biocompatibility and/or biostability characteristics. In at least one embodiment, catheter  10  and tubular structure  12  comprise a biocompatible plastic or elastomer, such as a medical-grade thermoplastic polyurethane resin (“TPU”). Examples of suitable TPUs include, without limitation, aliphatic polyether-based polyurethanes, aromatic polyether-based polyurethanes, and aliphatic polycarbonate-based polyurethanes. In certain embodiments, catheter  10  may comprise at least one thermoplastic polyurethane resin that is identical to a thermoplastic polyurethane resin utilized in tubular structure  12 . 
     Tubular structure  12  may be formed in any number of shapes and sizes and may be positioned to at least partially surround catheter  10 . In at least one embodiment, tubular structure  12  includes an aliphatic polycarbonate-based polyurethane and is configured to snugly fit around the catheter shaft (i.e., around an exterior surface of the catheter shaft). In certain embodiments, tubular structure  12  may also be configured to exhibit an initial length  11  ( FIG. 1 ) of between about 1 to about 3 centimeters. In addition, as illustrated in  FIG. 2 , tubular structure  12  may be configured to include a leading end  15  and a trailing end  19 , taken with respect to an intended direction of insertion or advancement of catheter  10  within a body. 
     As seen in  FIG. 2 , a stabilizing cuff  14  may be positioned near or proximate to tubular structure  12 . Depending on the intended direction of insertion or advancement of catheter  10 , stabilizing cuff  14  may be positioned near the center of tubular structure  12 , near leading end  15 , or near trailing end  19  (as is the case in  FIG. 2 ). In certain embodiments, stabilizing cuff  14  comprises a fabric cuff for encouraging tissue ingrowth subsequent to positioning stabilizing cuff  14  within a body. Generally speaking, stabilizing cuff  14  may be formed of any number or combination of materials capable of promoting tissue ingrowth, including, for example, polyesters such as polyethylene terephthalate. Stabilizing cuff  14  may also be formed in any number of shapes or sizes. In at least one embodiment, stabilizing cuff  14  comprises a strip or portion of a substantially planar sheet of tissue ingrowth fabric exhibiting a width equal to about 8 millimeters. In other embodiments, the stabilizing cuff  14  can have varying widths, for example, about 6 or about 10 millimeters. 
     As seen in  FIGS. 3 and 6  (discussed in detail below), stabilizing cuff  14  may be wrapped around (i.e., circumferentially surround) tubular structure  12  to cover the entire outer circumference of tubular structure  12 . Further, as discussed in greater detail below in connection with  FIG. 7 , stabilizing cuff segments  114  may be placed about select portions of an outer circumference of tubular structure  112 . After stabilizing cuff  14  has been positioned about tubular structure  12 , heat and/or pressure may then be applied to tubular structure  12  and stabilizing cuff  14  to affix stabilizing cuff  14  to tubular structure  12 . In certain embodiments, heat and pressure are applied using complementary “cuffing jaws,” which comprise heat-conductive molds comprising a selected external shape, as known in the art. According to at least one embodiment, stabilizing cuff  14  is affixed to tubular structure by closing a set of cuffing jaws onto stabilizing cuff  14  and tubular structure  12  at a temperature of about 375-380° Fahrenheit for around 15 to 45 seconds at about 60 psi. 
     After stabilizing cuff  14  is affixed to tubular structure  12 , a temporary sleeve  16  may be positioned about tubular structure  12  and stabilizing cuff  14 , as illustrated in  FIG. 3 . Temporary sleeve  16  may be formed in any number of shapes and sizes. In at least one embodiment, a length of temporary sleeve  16  may be equal to or greater than tubular structure  12 . For example, the length of temporary sleeve  16  may be about 0.5 to about 1 inches longer than length  11  ( FIG. 1 ) of tubular structure  12 . Temporary sleeve  16  may also be centrally positioned about tubular structure  12 , such that the midpoint of temporary sleeve  16  is substantially aligned with the midpoint of tubular structure  12 . 
     In one exemplary embodiment, temporary sleeve  16  comprises a heat-shrinkable material that contracts or shrinks when heat is applied. Although temporary sleeve  16  may be formed in any number of shapes and sizes, in at least one embodiment temporary sleeve  16  may be configured to include a pre-shrunk inner diameter of about 0.300 inches, and a shrunken or contracted inner diameter (i.e., after sufficient heat has been applied to the sleeve  16  to cause it to contract) substantially equivalent to the outer diameter of the catheter body. 
     In this exemplary embodiment, temporary sleeve  16  may be used both to compress or bias stabilizing cuff  14  and tubular structure  12  and to mold tubular structure  12  into a desired shape. For example, after sliding temporary sleeve  16  over both tubular structure  12  and stabilizing cuff  14 , heat may be applied to both temporary sleeve  16  and tubular structure  12  until a transition point (e.g., a melting/softening temperature or glass transition temperature) of one or both materials is reached and/or exceeded. Heat may be applied to tubular structure  12  and/or stabilizing cuff  14  in any number of ways known in the art, including, for example, by applying hot air using a hot air system. In at least one embodiment, air heated to a temperature of about 380° Fahrenheit is applied to tubular structure  12  and stabilizing cuff  14  until tubular structure  12  begins to softens or melts and temporary sleeve  16  begins to shrink or contract. As tubular structure  12  softens or melts, and as temporary sleeve  16  contracts, the contracting pressure applied by temporary sleeve  16  may bias and force tubular structure  12  into a desired shape. In at least one embodiment, this contracting pressure forces the tubular structure  12  into the tapered shape illustrated in  FIG. 4 . Specifically, the contracting pressure applied by temporary sleeve  16  may create a smooth and tapered transition between the exterior surface of catheter  10  and stabilizing cuff  14 . Temporary sleeve  16  may then be removed to allow the heated elements to cool, resulting in an exemplary catheter assembly  30 . 
     In another embodiment, temporary sleeve  16  may comprise a material (e.g., silicone) that does not shrink or contract in response to the application of heat. In this exemplary embodiment, a secondary set of cuffing jaws or molds may be used to compress or mold tubular structure  12  into a desired shape. For example, a secondary set of cuffing jaws embodying the inverse of the desired shape may be closed onto stabilizing cuff  14  and tubular structure  12  at a temperature of about 275° Fahrenheit at about 30 psi for around 45 seconds. Once a transition point (e.g., a melting/softening temperature or glass transition temperature) of tubular structure  12  is reached and/or exceeded, tubular structure  12  will begin to soften, melt, or even liquefy. As tubular structure  12  softens, the pressure applied by the cuffing jaws or mold may bias or force tubular structure  12  into a desired shape. In at least one embodiment, the heat and pressure applied by the cuffing jaws forces the tubular structure  12  into the tapered shape illustrated in  FIG. 4 , resulting in a smooth and tapered transition between the exterior surface of catheter  10  and stabilizing cuff  14 . The cuffing jaws and temporary sleeve  16  may then be removed to allow the heated elements to cool, resulting in exemplary catheter assembly  30 . 
     In the exemplary embodiment previously described (wherein a secondary set of cuffing jaws is used to shape tubular structure  12  into a desired shape, as opposed to using a heat-shrinkable material to shape the structure), temporary sleeve  16  may comprise an adhesion-resistant material, such as, for example, silicone, to inhibit adhesion between the cuffing jaws or mold and tubular structure  12 . 
     As illustrated in  FIG. 4 , in at least one embodiment, a catheter assembly  30  is created (in accordance with one or more of the processes described herein) comprising a tubular structure  12  including a leading end  15  shaped so as to facilitate advancement of stabilizing cuff  14  within a body. In certain embodiments, leading end  15  of tubular structure  12  is forced into the tapered shape illustrated in  FIG. 4 , resulting in a smooth and tapered transition from the outer diameter of catheter  10  to stabilizing cuff  14 . Such a transition may generally extend radially outwardly from the outer diameter of catheter  10  at a leading end  15  of tubular structure  12  in a tapered fashion toward a trailing end  19  of tubular structure  12 . In at least one embodiment, such a transition results in tubular structure  12  including an exterior surface that is at least partially conical in shape. Shaping tubular structure  12  in this manner effectively reduces the amount of force required to advance catheter  10  in a tunnel insertion direction  25 . 
     As shown in  FIG. 4 , an annular recess  22  may be defined in tubular structure  12 . In at least one embodiment, as illustrated in  FIG. 4 , stabilizing cuff  14  may be positioned substantially within annular recess  22 . In certain embodiments, annular recess  22  may be circumferentially continuous about substantially a selected circumference of tubular structure  12 . For example, as illustrated in  FIG. 6 , annular recess  22  may be defined about a selected circumferential region of tubular structure  12 , such that, when stabilizing cuff  14  is positioned within annular recess  22 , stabilizing cuff  14  extends continuously, circumferentially around tubular structure  12 . In another embodiment, one or more circumferentially separated recesses may be defined along select portions of the outer diameter of tubular structure. For example, as illustrated in  FIG. 7 , a plurality of recesses  122  may be defined along select portions of tubular structure  112 . A plurality of stabilizing cuff portions  114  may then be positioned within recesses  112 , separated by a plurality of protrusions  117 . 
     In addition to shaping tubular structure  12  in the manner illustrated in  FIGS. 1-4 , the application of pressure and heat by cuffing jaws and/or temporary sleeve  16  may flatten or smooth the surface of stabilizing cuff  14 , thereby further reducing the amount of force required to advance catheter  10  within a body. More specifically, the pressure applied to stabilizing cuff  14  helps to flatten the stabilizing cuff&#39;s normally fluffy ingrowth fabric. Flattening or smoothing the ingrowth fabric of stabilizing cuff  14  in this manner may reduce the amount of drag created by the cuff, and may avoid the need for the application of conventional flattening adhesives which can be biodegradable; which, as explained above, may impede tissue ingrowth or result in a rigid, inflexible cuff structure. 
     Moreover, the pressure and heat applied to stabilizing cuff  14  and tubular structure  12  in accordance with one or more of the exemplary embodiments described herein may also force at least a portion of stabilizing cuff  14  to become embedded in the tubular structure  12 . Specifically, as tubular structure  12  begins to soften or melt upon application of sufficient heat, pressure applied by one or more of the apparatuses described herein may force at least a portion of the tubular structure  12  to flow into stabilizing cuff  14 . For example, as illustrated in  FIG. 8 , a stabilizing cuff  214  may become at least partially embedded within the outer surface of tubular structure  212 , as represented by depth of penetration line  223 . As will be appreciated by one of ordinary skill in the art, at least partially embedding stabilizing cuff  214  within tubular structure  212  in this manner may strengthen the adhesion bond between stabilizing cuff  214  and tubular structure  212  to form a robust cuff structure. In addition, at least partially embedding stabilizing cuff  214  in this manner may reduce the outer diameter and profile of the cuff assembly, thereby reducing the amount of force required to advance catheter  210  within a body. 
     Similarly, in certain embodiments the pressure and heat applied to tubular structure  212  and catheter  210  may force at least a portion of tubular structure  212  to become embedded within the outer surface of catheter  210 , as represented by depth of penetration line  221 . In at least one embodiment, catheter  210  comprises a thermoplastic polyurethane resin that is substantially identical to a thermoplastic polyurethane resin utilized in tubular structure  212  to facilitate the embedding of tubular structure  212  within catheter  210 . As with tubular structure  212  and stabilizing cuff  214 , embedding tubular structure  212  within catheter  210  in this manner may strengthen the adhesion bond between tubular structure  212  and catheter  210 , resulting in a robust cuff structure. In addition, at least partially embedding tubular structure  212  in this manner further may reduce the outer diameter and profile of the cuff assembly, thereby reducing the amount of force required to advance catheter  210  within a body. 
       FIG. 5  is a perspective view of an exemplary catheter system  50  comprising a catheter assembly  30  according to certain embodiments. Catheter assembly  30  generally represents each catheter assembly described and/or illustrated herein, including the catheter assembly illustrated in  FIG. 12 . Generally speaking, catheter system  50  represents any system capable of introducing or removing fluid from a body, such as a human body. In any of the embodiments disclosed herein, the catheter can include one or more lumens. For example, catheter system  50  may represent a hemodialysis catheter system, an infusion catheter system, a cardiovascular access catheter system, a renal catheter system, a parenteral nutrition catheter system, a peritoneal dialysis catheter system, or any other catheter system without limitation. 
       FIGS. 9-11  illustrate, in schematic cross-sectional views, an additional exemplary method of manufacturing a catheter assembly. Similar to  FIGS. 1-3 , these figures illustrate a tubular structure  312  slid over, or positioned generally about, the exterior surface of a catheter  310 . However, in contrast to the tubular structure illustrated in  FIGS. 1-3 , tubular structure  312  may be preformed (i.e, shaped prior to positioning the tubular structure about the exterior surface of the catheter) to include at least one tapered end, such as the exemplary tapered surface extending generally from leading end  315  in  FIGS. 9 and 10 . More specifically, at least one end of tubular structure  312  may be preformed to taper down and away from an outer surface of stabilizing cuff  314  towards the outer diameter of catheter  310 . 
     In at least one embodiment, the preformed tapered end is provided on an end of tubular structure  312  facing a direction of insertion, such as leading end  315  in  FIGS. 9 and 10 . Tubular structure  312  may also, however, be preformed such that both of its ends taper towards the outer surface of catheter  310 . As illustrated in  FIGS. 9-11 , after preformed tubular structure  312  is positioned about catheter  310 , a stabilizing cuff  314  may be affixed to tubular structure  312  and tubular structure  312  may be molded into a desired shape, in accordance with one or more of the embodiments discussed or illustrated herein. In at least one embodiment, catheter assembly  30  illustrated in  FIG. 4  results from this process. 
     Preforming one or more of the ends of tubular structure  312  to include a tapered surface in this manner may reduce the amount of heat and pressure required to form the resulting catheter assembly. Specifically, the tapered shape of the ends of preformed tubular structure  312  may reduce the distance portions of tubular structure  312  must travel to form the desired shape illustrated in  FIG. 4 . Preformed tubular structure  312  may also reduce the amount of time required to mold tubular structure  312  into the desired shape, resulting in greater manufacturing efficiencies. In addition, preformed tubular structure  312  may help increase the yield of the manufacturing process. 
     The preceding description has been provided to enable others skilled in the art to best utilize various aspects of the exemplary embodiments described herein. This exemplary description is not intended to be exhaustive or to be limited to any precise form disclosed. Many modifications and variations are possible without departing from the spirit and scope of the instant disclosure. For example, as illustrated in  FIG. 12 , a catheter assembly may be formed to facilitate advancement of a stabilizing cuff  414  within a body in either an antigrade direction  425  or a retrograde direction  427 . Specifically, ends  415  and  419  of tubular structure  412  may be molded into the tapered shape illustrated in  FIG. 12 , resulting in a smooth and tapered transition from the outer diameter of a catheter  410  to stabilizing cuff  414  on either side of stabilizing cuff  414 . Similarly, tubular structure  12  in  FIG. 4  may shaped to include a tapered surface on either side of stabilizing cuff  14 , as required. 
     In addition, the length of the tapered surfaces provided in the catheter assemblies illustrated in  FIGS. 4 and 12 , represented by element numbers  13  and  413 , respectively, may be modified or adjusted as necessary. For example, a longer, more gradual taper may be provided to further reduce the transition angle between the outer surface of catheters  10 ,  410  and stabilizing cuffs  14 ,  414 , respectively. Similarly, a shorter, steeper taper may be provided in order to reduce the amount of time and heat required to form the tapered shape and to control the quality and finish of the tapered surface. In at least one embodiment, the lengths  13  and  413  of the catheter assemblies illustrated in  FIGS. 4 and 12  are equal to about 1 to 3 centimeters. 
     In another embodiment, a catheter assembly  500  includes a catheter body  502 , a tapered member  504 , a tubular member  506 , and a stabilizing cuff  508  that can be at least partially embedded or affixed to the tubular member  506 . In particular embodiments, the tapered member  504  can be spaced away from the tubular member  506 . 
     For ease of use, the words “including” and “having,” as used in the specification and claims, are interchangeable with and have the same meaning as the word “comprising.” It is intended that the scope of the instant disclosure be defined by the following claims.