Patent Publication Number: US-2020297905-A1

Title: Vacuum assisted skin penetrating appliance with external interface

Description:
RELATED APPLICATIONS 
     This application claims priority benefit of U.S. Provisional Application Ser. No. 62/822,673 filed 22 Mar. 2019, the contents of which are hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention in general relates to medical devices and systems and in particular to a protective external interface for preventing infection at insertion sites of indwelling medical lines. 
     BACKGROUND OF THE INVENTION 
     In patients requiring long-term intravenous (IV) drug therapy, total parenteral nutrition, temporary access for kidney dialysis, or frequent blood testing, repeated access to a vein may be necessary over an extended period of time. Multiple needle sticks into a vein can be difficult, painful, and time-consuming. In such cases, a thin, flexible tube system known as a central venous catheter (also called a central line) may be inserted under the skin and into a large vein. This type of catheter may be safely and comfortably left in place for percutaneous access for days, weeks, or months. Additionally, peripherally inserted central catheters (PICC), skeletal guide wires, cardiac assist device lines, or other instruments may be kept in place for weeks or months with a precutaneous access device (PAD). 
     A common problem associated with implantation of a cutaneous access device (PAD) or other skin penetrating appliance is skin regeneration about the periphery of the appliance to form an immunoprotective seal against infection. New cell growth and maintenance is typically frustrated by the considerable mechanical forces exerted on the interfacial layer of cells. In order to facilitate skin regeneration about the exterior of the appliance, subject cells are often harvested and grown in culture onto appliance surfaces for several days prior to implantation in order to allow an interfacial cell layer to colonize appliance surfaces in advance of implantation. Unfortunately, cell culturing has met with limited acceptance owing to the need for a cell harvesting surgical procedure preceding the implantation procedure. Additionally, maintaining tissue culture integrity is also a complex and time-consuming task. 
     A related context in which cell growth is needed is wound healing, with DACRON® based random felt meshes have been used to promote cell regrowth in the vicinity of a wound, such felts have uncontrolled pore sizes that harbor bacterial growth pockets. 
     U.S. Pat. 7,704,225 to Kantrowitz solves many of these aforementioned problems by providing cell channeling contours, porous biodegradable polymers and the application of vacuum to promote cellular growth towards the surface the neck of a PAD. The facilitating of rapid cellular colonization of a PAD neck allows the subject to act as their own cell culture facility and as such affords more rapid stabilization of the PAD, and lower incidence of separation and infection. 
       FIG. 1A  illustrates existing wound dressing  3  for prevention of infection at skin entry insertion sites of a catheter  1 .  FIG. 1B  is a cutaway side view of the catheter  1  of  FIG. 1A  showing the skin layers and the insertion site  5 . As noted the configuration shown in  FIGS. 1A and 1B  for catheters is prone to infection. Furthermore, as previously noted pulling of the catheter  1  and the considerable mechanical forces exerted on the interfacial layer of cells frustrates the healing process and makes the patient susceptible to infection at the insertion site. 
       FIG. 2  depicts a PAD generally at  100  as shown in U.S. application Ser. No. 13/416,546 to Kantrowitz. A cap  102  is formed of a material such as silicone, a polymer, or a metal and serves to keep debris from entering the device  100 . Preferably, the cap  102  is remote from the surface of the epidermis E. The medical appliance  34  depicted as a catheter and vacuum or hydrodynamic draw tubing  104  pass through complementary openings  106  and  108 , respectively formed in the cap  102 . The tubing  104  provides fluid communication between a vacuum or hydrodynamic draw source  22  and an inner sleeve  12   d.  The inner sleeve  12   d  is characterized by a large and rigid pore matrix  18  in fluid communication to a vacuum source  22  such that the source  22  draws (arrow  22 D) tissue fluid and fibroblasts  21  into the sleeve  12   d.  Sleeve  12   d  has a surface  24  that is optionally nanotextured to promote fibroblast adhesion. The surface  24  is optionally decorated with a pattern of contoured cell-conveying channels. It is appreciated that inner sleeve  12   d  optionally includes matrix  26  thereover, a coating substance  27 , or a combination thereof. The coating  27  is appreciated to need not cover the entire surface  24 . The tissue contacting surface  29  of substance  27  is optionally nanotextured. A flange  112  is provided to stabilize the implanted device  100  within the subcuteanous layer S. A flange  112  is constructed from materials and formed by methods conventional to the art. For example, those detailed in U.S. Pat. Nos. 4,634,422; 4,668,222; 5,059,186; 5,120,313; 5,250,025; 5,814,058; 5,997,524; and 6,503,228. 
     U.S. application Ser. No. 15/555,952 assigned to the assignee of this application discloses a modular external interface that includes a main body with an aperture configured to form a collar seal about an external neck portion of a skin penetrating appliance, such as the PAD  100  of  FIG. 2 , where a slit extends outward from the aperture. A portal is configured for insertion of a vacuum tube is on the main body, where the portal is in fluid communication with a vacuum channel on a bottom side of the main body. A foam layer is positioned under the main body, and at least one driveline inserted through the aperture and into the appliance. The modular external interface provides additional mechanical stability to an implanted PAD so as to speed healing around a semi-permanent implanted PAD, as well as connection points for vacuum lines and at least one drive line for the insertion of medical devices. 
       FIGS. 3A-3C  illustrate the aforementioned modular external interface housing  200  coupled to the PAD  100  of  FIG. 2 . The modular external interface  200  forms a collar about the neck  110  of the PAD  100  with the main body  216  with a locking feature  218 , such as a male extension that engages a female receptacle or cavity as a mechanical overlap connection. In a specific embodiment the main body  216  is made of silicone. As best shown in  FIG. 4 , the collar seal between the main body  216  and the neck  110  of the PAD  100  forms a hermetic seal with a gasket  230 , which in a specific embodiment is a flexible gasket integrated into the main body  216 . In a specific embodiment the gasket  230  may be a floating gasket. The stabilization of the PAD  100  within the skin to form a germ-free barrier requires subject cells to grow onto the neck surfaces  16  of the PAD  100  adjacent to the subject&#39;s epidermis E. The neck surface region  16  is adapted to promote growth of autologous fibroblast cells thereon. A suitable exterior side surface substrate for fibroblast growth is a nanotextured polycarbonate (LEXAN®). 
     The modular external interface  200  is secured and sealed to an outer layer of a patient&#39;s skin with a medical dressing. In a specific embodiment the medical dressing is a preform patterned and shaped to conform to the exterior of the modular external interface  200 . In a specific embodiment the medical dressing preform may be in two halves ( 212 ,  214 ) that overlap. In a specific embodiment the medical dressing preform may be transparent. In a specific embodiment the medical dressing preform may be made of Tegaderm™ manufactured by Minnesota Mining and Manufacturing Company. 
     The modular external interface  200  has a central opening adapted at least one drive line  220  for insertion into a PAD, and a portal  224  for a vacuum line  222 . As best shown in  FIG. 4  a skin protection layer  228  and a foam disc (not visible) are positioned in the interior of the modular external interface  200 . 
     While there have been many advances in skin penetrating appliance designs for preventing infection at the site of skin access, there continues to be a need for improved external interfaces for implanted appliances. In particular, infection at insertion sites of short and long-term IV lines, chronic central venous access, catheters, peritoneal dialysis lines, heart and total heart assist device drive lines, and orthopedic (prosthetics osseo-integration) related applications continue to require new and innovative solutions for the acceleration of tissue healing at an insertion site. 
     Thus, there exists a need for improved and integrated solutions for accelerated tissue healing to reduce and prevent infection at insertion sites for infusion lines, drive lines, and medical devices. 
     SUMMARY OF THE INVENTION 
     An external protective interface is provided for percutaneous access. The external protective interface includes a cover defining a volume that encloses an insertion site of a percutaneous access device or tube, the cover having a lip about the perimeter of the cover, and a portal with a set of ports for insertion of a vacuum line and at least one driveline, the cover having an opening adapted to fit over the portal. A skin protection layer fits around the percutaneous access device and positions the portal against a subject&#39;s skin and helps to maintain a negative pressure against the surface of the patient&#39;s skin as supplied by the vacuum line, the lip resting on the skin protection layer. The external protective interface further includes a gasket that is adapted to conform to the shape of the lip and of the portal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1A  illustrates existing wound dressing for prevention of infection at skin entry insertion sites of catheters; 
         FIG. 1B  is a cutaway side view of the catheter of  FIG. 1A ; 
         FIG. 2  is a prior art, partial cutaway view of a flanged percutaneous access device (PAD) with relative dimensions of aspect exaggerated for visual clarity; 
         FIGS. 3A-3C  are prior art perspective views of a modular external interface seal for a PAD appliance; 
         FIG. 4  illustrates a side cross sectional view of  FIG. 3C ; 
         FIG. 5  is an exploded view of an external protective interface showing a dressing, cover, an implanted tube for an infusion or insertion line, and a vacuum line according to an embodiment of the invention; and 
         FIG. 6  illustrates the dressing applied to the external protective interface according to an embodiment of the invention. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     The present invention is an external protective interface for intravenous infusion lines, drive lines, vacuum lines, and monitoring lines for percutaneous access. The external protective interface acts as an airtight seal in concert with a vacuum line to promote accelerated tissue healing to reduce and prevent infection at insertion sites for infusion lines, drive lines, and medical devices. Embodiments of the protective external interface provide additional mechanical stability to an implanted tube or PAD or so as to speed healing around a semi-permanent implanted tube or PAD, as well as connection points for vacuum lines and at least one drive line for the insertion of medical devices. The dense fibroblast ingrowth encouraged by embodiments of the invention acts to strengthen barriers to infection at the insertion site. Embodiments of the inventive external protective interface may be illustratively used for chronic central venous access, peritoneal dialysis, heart assist and total heart drivelines, prosthetics (osseo-integration—limb replacement), and short and long term IV access (reduction of bio-burden adjacent to non-adhering catheters). 
     While embodiments of the external protective interface is shown with a percutaneous tube, it is appreciated that it is applicable to a variety of such implant appliances including an embedded percutaneous access device (PAD), a catheter, a PICC line, an IV, a Steinman pin, and a Kirschner wire. Embodiments of the external protective interface provide for the hermaticity in the vicinity of the insertion site of the skin-appliance (PAD) interface with fluid exudate or transudate egressing from the vicinity of the skin-PAD interface via a vacuum or low pressure tube. 
     Referring now to the figures,  FIG. 5  illustrates an exploded view of an inventive embodiment of an external protective interface  300  with a cover  302  that fits over a portal  324 , the portal having ports for insertion of a vacuum line  222  and at least one driveline  220  that is shown inserted into a percutaneous tube  312 . The percutaneous tube  312  as disclosed in U.S. application Ser. No. 15/125,273 assigned to the assignee of this application has an exterior wall that is adapted to promote growth of autologous fibroblast cells thereon. A suitable exterior side surface substrate for fibroblast growth is a nanotextured polycarbonate (LEXAN®). In certain embodiments the exterior surface of the percutaneous tube  312  are etched by a laser or by a chemical treatment to obtain a surface finish or roughness to promote cell growth attachment to the exterior surface of the percutaneous tube  312 . A skin protection layer  328  fits around the percutaneous tube  312  and positions the portal  324  against the skin and helps to maintain a negative pressure against the surface of the skin as supplied by the vacuum line  222 . The portal  324  also supports the driveline  220  until the driveline  220  is inserted into the percutaneous tube  312 . The modular external interface  300  and cover  302  is secured and sealed to an outer layer of a patient&#39;s skin with a medical dressing  304 . In a specific embodiment the medical dressing is a preform  304  patterned and shaped to conform to a flexible gasket  308  and an exterior lip  310  of the cover  302  of the modular external interface  300 . In a specific embodiment the medical dressing preform  304  may be transparent. In a specific embodiment the medical dressing preform  304  may be made of Tegaderm™ manufactured by Minnesota Mining and Manufacturing Company. Removable clip  306  seals the flexible gasket  308  to the portal  324  that provides a hermetic seal. 
       FIG. 6  illustrates the dressing applied to the external protective interface  300  according to an embodiment of the invention with the vacuum line  222  and driveline  220  inserted to the portal  324 . 
     The present invention is further detailed in the application appendix, the contents of which are hereby incorporated by reference. 
     Patent documents and publications mentioned in the specification are indicative of the levels of those skilled in the art to which the invention pertains. These documents and publications are incorporated herein by reference to the same extent as if each individual document or publication was specifically and individually incorporated herein by reference. 
     The foregoing description is illustrative of particular embodiments of the invention, but is not meant to be a limitation upon the practice thereof. The following claims, including all equivalents thereof, are intended to define the scope of the invention.