Abstract:
A transcutaneous access device includes a subcutaneous skirt, a transcutaneous neck and an extracutaneous extensible sleeve all of which may be made of an inexpensive plastic material. Preferably, the skirt and neck are covered with a porous bed material which encourages the growth of tissue and collagen. The device functions as a conduit for an access catheter and is sized to minimize contact with the catheter and to allow vertical and horizontal motion of the catheter relative to the implanted portions of the access device so that twisting and stretching of the tissue adjacent to the implanted access device caused by normal body motions do not upset the biological seal that forms around the access device.

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of Ser. No. 09/157,977, filed Sep. 21, 1998, now U.S. Pat. No. 6,099,508, which is a continuation of Ser. No. 08/738,011, filed Oct. 25, 1996, now U.S. Pat. No. 5,882,341, which is a continuation-in-part of Ser. No. 08/499,543, filed Jul. 7, 1995, now U.S. Pat. No. 5,662,616. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a transcutaneous access device. It relates more particularly to a device of this type to facilitate access to the body through the skin by catheters and similar percutaneous devices. 
     BACKGROUND OF THE INVENTION 
     There has of late been increasing use of catheters to provide prolonged or repeated access to the internal organs of chronically ill patients. For example, catheters are used to access a patient&#39;s venous system for the administration of intravenous (IV) fluids, antibiotics, and chemotherapy. Catheters are also implanted in patients who require repeated access to the peritoneum for peritoneal dialysis. 
     Other than occlusion, the most common complications arising with long-standing implants are exit-site infection, tunnel infection, local abscesses and even sepsis. Many of these complications arise because the skin adjacent to the catheter does not heal to form a tight barrier to infection. Rather, epidermal cells tend to invaginate or migrate inward along the catheter and never form a tight biological seal around the catheter. Also, tunnels are created through which body fluids may exude thereby creating a site for infection. 
     In an attempt to overcome these problems, a catheter has been devised which includes a button-like skirt with a raised neck and a central hole for accommodating a tube. The tube has a corrugated segment extending above the button neck which allows the external portion of the tube to be flexed so as to absorb shocks. The skirt, including a portion of the neck thereof, is covered with a porous material, such as polyester velour, to allow for cell infiltration. When that device is implanted, the epidermal cells tend to migrate or invaginate downward along the neck to the skirt where they form a biological seal with the collagen and subcutaneous tissue growth on the porous covering of the button; see U.S. Pat. No. 4,886,502. 
     While that concept was relatively successful in animals, it has had limited success in human trials because normal body motions caused stretching of the tissue adjacent to the catheter and exerted torsion on the catheter. Such movements of the tissue relative to the button, which is held stationary by the external segment of the catheter tube, results in disruption of the biological seal between the catheter and the adjacent tissue. Such disruption may also occur when the external segment of the catheter tube is moved accidentally or intentionally when connecting and disconnecting the catheter tube to the infusate source. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention aims to provide a transcutaneous access device for a catheter which should circumvent most of the problems caused by relative movement of the catheter and the tissue surrounding the catheter. 
     Another object of the invention is to provide a transcutaneous access device which, when implanted, provides a tight biological seal between the device and adjacent tissue. 
     A further object of the invention is to provide a device of this type which reduces the risk of infection; 
     Yet another object of the invention is to provide a transcutaneous access device which is relatively easy to manufacture in quantity. 
     Other objects will, in part, be obvious and will, in part, appear hereinafter. The invention accordingly comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in the following detailed description, and the scope of the invention will be indicated in the claims. 
     The transcutaneous access device of this invention comprises a flat button with an opening therethrough and an integral upstanding tubular neck in registration with that opening. Formed as an integral extension of that neck is a flexible, extensible sleeve e.g. elastic tubing or a bellows, whose free end is terminated by a collar which connects to a conventional access catheter whose catheter tube extends all the way through the lumen formed by the sleeve or tube, neck and button of the access device. 
     In accordance with the invention, the lumen of the present device is large enough to provide appreciable clearance between the walls of the lumen and the access catheter so as to minimize contact between the access device and the access catheter. Thus, when the device is implanted, the collar and upper end segment of the catheter tube are free to move relative to the button and surrounding tissue. 
     In one preferred embodiment of the invention, the access device is permanently connected, via the free end of the sleeve, to the catheter. In another embodiment, two similar access devices are positioned back to back on the catheter with the free ends of their sleeves connected to the catheter, preferably such that the sleeves are in a collapsed condition. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which: 
     FIG. 1 is an isometric view with parts broken away of a transcutaneous access device incorporating the invention; 
     FIG. 2 is a sectional view with parts in elevation showing the FIG. 1 access device implanted in the body and ready for use; 
     FIG. 3 is a view similar to FIG. 1 of another embodiment of the access device; 
     FIG. 4 is a sectional view with parts in elevation showing yet another embodiment of the invention, and 
     FIG. 5 is a view in elevation of a further invention embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 and 2 of the drawing, one embodiment of my access device comprises a flat, button-like main body or skirt  10  having a central opening  12  and an array of three to six through-holes  14  distributed around opening  12 . Extending out from one side of skirt  10  in registration with opening  12  is an integral, tubular neck  16  whose lumen is in registration with opening  12 . Skirt  10  and neck  16  should be stiff enough to maintain their shapes but be somewhat flexible and compliant so that when implanted they flex and “give” with the patient&#39;s dermis. In the illustrated device, the neck  16  extends out from skirt  10  at an angle; however, the neck could just as well be perpendicular to the skirt  10 . 
     The device also includes a highly flexible, extensible tubular sleeve  22  extending from the free end of neck  16 . In the FIGS. 1 and 2 device, sleeve  22  is a pleated accordion-like tube which forms a bellows and which is terminated at its free end by a cylindrical collar  24 . Thus, the sleeve  22  allows the collar  24  to be moved toward and away from neck  16  in the order of 2-5 cm, as well as in all directions about the longitudinal axis of neck  16 . The skirt  10 , neck  16 , sleeve  22  and collar  24  define a continuous, uniformly sized lumen  25  which extends through the entire device. 
     As best seen in FIG. 2, the collar  24  is formed with an internal lip  24   a  to provide a mechanical connection to an associated access catheter as will be described later. 
     The access device, including the skirt  10 , neck  16 , sleeve  22  and collar  24  are preferably formed of a flexible, thermally stable, biocompatible material such as flexible, medical grade polyurethane. The accordion-like sleeve  22  may be configured by placing a tubular extension of the neck  16  in a heated female mold and applying gas pressure inside the tube to force the tube walls to conform to the mold. The neck may then be secured to the button-like skirt  10  by welding. Alternatively, the device may be molded as a unitary part. 
     Preferably, the entire surface of the body or skirt  10  is covered by a porous covering or bed  26  of a material such as medical grade polyester (Dacron) velour. Such a covered skirt  10  is available as Part No. 600K61121, from the U.S Catheter and Instrument Company of Glenfalls, N.Y. The covering encourages cell infiltration and the formation of subcutaneous tissue and collagen and thus obtains a better bond than the PTFE material used in the above patent. 
     Typically, when the access device is used for peritoneal dialysis, the skirt  10  is in the order of 2.5 cm in diameter, the neck  16  is about 0.5 cm long, the sleeve  22  is about 2 to 24 cm long and the diameter of the device&#39;s lumen  25  is in the order of 0.4 to 0.8 cm. On the other hand, when the device is used for vascular access, skirt  10  may be smaller, e.g., 1 cm in diameter, with the lengths of the neck and sleeve being 0.5 cm and 4 cm, respectively. In that event, the lumen  25  diameter may be in the order of 0.3 to 0.5 cm. 
     Referring to FIG. 2, the access device is implanted so that the skirt  10  is anchored in the subcutaneous tissue  32  and the covered neck  16  extends out through the dermal layer  34  and epidermal layer  36  of the skin S through an opening O. In time, tissue growth penetrates the through-holes  14  to help anchor the access device. Those same holes also allow for fluid drainage and for sutures to anchor the device to tissue  32 . As noted previously, the covering  26  provides a porous bed to encourage the growth of tissue and collagen around the body  10  to provide a biological seal with the epidermal cells which migrate or invaginate down around neck  16  until they reach the covering  26 . 
     The access device is designed to be used in conjunction with an access catheter or catheter tube such as the one shown generally at  42  in FIG.  2 . The illustrated catheter is a vascular access catheter. However, the catheter could just as well be a peritoneal access catheter. Suffice it to say that the catheter  42  includes a tube  44  which has an internal segment  44   a  which extends from the skin line along neck  16  and through body  10  to a selected infusion site such as the subclavian vein. The catheter tube also includes an external segment  44   b  which extends from the skin line through sleeve  22  and collar  24  to a Y-fitting  46  to which is connected a pair of fluid inlet tubes  48   a  and  48   b  so as to allow fluid from two different sources to be flowed to the catheter tube  44 . 
     When the catheter  42  is properly seated in the access device, the lip  24   a  of the device&#39;s collar  24  is arranged to releasably engage over a radial flange  46   a  usually present at the lower end of the catheter fitting  46  to mechanically connect the catheter to the access device at the free end of the device&#39;s flexible sleeve  22 . However, as noted previously, the device&#39;s lumen  25  is sized to minimize contact with the catheter tube  44  and so as not to inhibit motion of the catheter tube. Therefore, any motion of the internal catheter tube segment  44   a  caused by movements of the patient&#39;s body is substantially decoupled from the implanted portions of the access device, i.e., skirt  10  and neck  16 . By the same token, if the external segment  44   b  of the catheter tube  44  should be moved accidentally or intentionally when connecting or disconnecting the catheter, the accordion-like sleeve  22  is able to flex, extend and contract as needed to accommodate such movement so that essentially no motion is coupled to the implanted portions of the access device. Resultantly, a tight biological seal is maintained between the access device and the surrounding tissue. 
     Indeed, actual experiments with prototype devices have shown that there are no signs of infection at the implantation sites even after the devices have been in place for prolonged periods. 
     Refer now to FIG. 3 which shows a second embodiment of my transcutaneous access device. It is similar to the FIG. 1 embodiment, except that its button-like skirt  50 , tubular neck  52  and extensible sleeve  54  are formed as a unitary part. An annular connector member  56  which may be similar to member  24  is provided at the free end of the sleeve  54 . Thus, the device has an axial passage or lumen  58  which extends the entire length of the device for accommodating a catheter tube  44  shown in phantom in FIG. 3. A suitable material for the button-neck-sleeve unit is medical grade polyurethane sold under the designation Tecoflex EG 80A by Thermedics, Inc., Woburn, Mass. 
     In this case, the extensible sleeve  52  is not accordion-like. Rather, it is a thin-walled (e.g., 0.030 in.), elastic tube which can readily flex and extend lengthwise by the required amount, i.e., a few centimeters. 
     For most applications, sleeve  54  is more flexible and extensible than skirt  50  and neck  52 . To achieve this result, the device is formed so that the skirt and neck have a greater wall thickness than the sleeve. 
     As in the FIG. 1 device, porous bed material is applied to exterior surfaces of the skirt  50  and neck  52 . This material may be the same as or similar to the material used for bed  26  described above. Here, however, the material is applied in two parts. An annular piece  60   a  of bed material is slid onto the sleeve  54  and neck  52  and folded as shown in FIG. 3 so that it covers the upper surface of the skirt and encircles the neck  52 . It may be secured there by any suitable adhesive. To assure placement of the material piece  60   a  at the correct elevation on the neck  52  indicium  62  may be molded into or inscribed around neck  52 . 
     Another annular piece  60   b  of bed material is adhered to the undersurface of skirt  50 , the opening through piece  60   b  being substantially the same size as lumen  58 . 
     After being secured to skirt  50 , the bed material pieces  60   a  and  60   b  may be trimmed so that their outer edges are even with the periphery of skirt  50 . 
     The FIG. 3 embodiment of the device has all of the attributes of the FIG. 1 embodiment and functions in the same way described above in connection with the FIG. 1 embodiment. 
     In many applications it is desirable to minimize the length of the annular space between the access device and the catheter tube extending through that device. FIG. 4 illustrates an access device  70  which accomplishes this objective. The device is connected to a catheter tube  72  having a standard connector  74 , e.g., a Luer, at its outer end. 
     This access device  70  includes an annular flexible skirt  78  having a central opening  82  and an upstanding neck  78   a  both of which are appreciably larger than the outer diameter of tube  72 . Neck  78   a  is permanently bonded to a flange  86   a  formed at the lower end of a flexible extensible sleeve or extension  86 , e.g., a bellows (FIG. 4) or elastic tube (FIG.  3 ), having a collar  86   b  at its opposite or upper end. As with the other device embodiments, means are provided for connecting the collar  86   b  to the catheter tube. In this case, however, the connecting means are constituted by a bonding  87  of collar  86   b  to the tube. If desired, an adapter sleeve may be present between tube  72  and collar  86   b  to improve the bond. The sleeve  86 , including its flange  86   a  and collar  86   b,  has an inside diameter that is appreciably larger than that of tube  72  so that the neck  78   a,  skirt opening  82 , sleeve  86 , flange  86   a  and collar  86   b  define a continuous lumen which extends through the entire device  70 . This allows the collar  86   b  to be moved toward and away from skirt  78  as well as in all directions about the longitudinal axis of the skirt. 
     As with the other access device embodiments, preferably skirt  78  is made of or covered by a porous material, e.g. polyester, velour, which encourages cell in growth. Also, suture holes may be provided in the skirt. 
     As is apparent from FIG. 4, only a single tube extends from collar  86   b  to connector  74 . Therefore, there is no annular space around that segment of the tubing which could be a site for unwanted bacterial growth. 
     Refer now to FIG. 5 which illustrates yet another embodiment of my invention consisting essentially of two of the access devices depicted in FIG. 4 positioned back to back on catheter tube  72 . The two mirror image access devices are shown generally at  70  and  70 ′ and their corresponding parts carry the same identifying numerals (unprimed and primed) which are the same as in FIG.  4 . The skirts  78  and  78 ′ of the two access devices are connected together by adhesive bond  92  or the like and the collars  86   b  , and  86   b ′ of the two devices are bonded or otherwise secured to tubing  72 . Thus, the two skirts  78 ,  78 ′ are free to float relative to the catheter tube  72  and the collars. 
     Preferably, the collars  86   b,    86   b ′ are connected to tube  72  such that the two sleeves  86 ,  86 ′ are under some compression, e.g., the bellows (FIG. 4) are collapsed to some extent. This assures that when the access device is implanted so that the skirts  78 ,  78 ′ are anchored in subcutaneous tissue, any tension on the internal catheter tube segment  72   a  caused by movements of the patient&#39;s body is substantially decoupled from the implanted portions of the device, i.e., the skirts  78 ,  78 ′ and necks  78   a,    78   a ′. Likewise, if the external segment  72   b  of the catheter tube  72  should be moved accidentally or intentionally when connecting or disconnecting the catheter, the external sleeve  86  is able to flex, extend and contract as needed to accommodate such movement. Resultantly, no motion is coupled to the implanted portions of the access device which could upset the biological seal maintained between skirts  78 ,  78  ′ and the surrounding tissue. 
     Of course, in the FIG. 5 device, the two layers  78 ,  78  ′ could be combined into a single skirt with necks projecting from opposite faces of that skirt. 
     As seen from the foregoing, my transcutaneous access device is, for the most part, composed of plastic parts which can be made in quantity relatively easily and inexpensively. Therefore, it should find wide application wherever it is necessary to maintain catheters in situ for a long period of time. 
     It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 
     It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention described herein.