Percutaneous access device

A percutaneous access device includes a body having a horizontal disc-like base flange and a frusto conical projection extending centrally upwardly from one side of the base flange. An elongate flexible tube extends loosely through a bore through the projection and base flange and is sealingly bonded to the body adjacent the bottom of the bore. A coating of a silicone-polycarbonate is applied to the outer surface of the projection and is formed with a multiplicity of microscopic pores to facilitate the bonding of dermal cells to the device upon implantation. The body is of a relatively soft, flexible, biocompatible material so that the device absorbs forces tending to displace the implanted device.

BACKGROUND OF THE INVENTION 
I. Field of the Invention 
The present invention is directed to a percutaneous access device adapted 
to be implanted within a patient on a long-term basis. 
II. Description of the Related Art 
Percutaneous access devices (hereinafter PAD) are employed to provide a 
through-the-skin coupling or connection between an organ or device 
implanted within the human body and some external device as, for example, 
to introduce or withdraw fluids from the patient's body or to establish 
electrical or pneumatic connections to an implanted device, such as a 
dynamic aortic patch of the type disclosed in U.S. Pat. No. 4,630,597. The 
PAD must protrude through the skin and, as set forth in more detail in 
U.S. Pat. No. 4,634,422, a primary concern is that of preventing the 
development of infection which is prone to occur at the opening in the 
skin through which the device projects. U.S. Pat. No. 4,634,422 is 
directed to a PAD and implanting technique which achieves a firm bond 
between the underlying dermal layer of the skin and the projecting portion 
of the PAD to prevent down growth of the epidermal layer of the skin to 
prevent marsupialization of the PAD and to prevent sinus tract formation 
caused by epidermal cell proliferation. The PAD of U.S. Pat. No. 4,634,422 
includes a removable sleeve which, when assembled on the PAD, forms that 
portion of the external surface of the projection which passes through the 
dermal layer. In preparation for implantation, this sleeve is removed from 
the PAD and its external surface is formed, by nuclear bombardment, with a 
plurality of tiny pores. A coating of dermal cells is then cultured on 
this porous surface by techniques described in U.S. Pat. No. 4,634,422, 
this dermal cell coating growing into the pores of the sleeve surface to 
firmly mechanically bond the coating to the sleeve surface. Upon 
reassembly of the sleeve on the PAD and implantation of the PAD into the 
patient, the dermal cells of the patient will bond to those of the dermal 
cell coating on the sleeve within a relatively short time to form a 
barrier layer, preventing down growth of the epidermis along the side of 
the sleeve. 
While the PAD and implantation techniques described in U.S. Pat. No. 
4,634,422 present several major advantages over prior art devices, the 
sleeve employed is of a rigid material. In those applications where the 
PAD was employed as a plug-in connector to external, electrical or 
pneumatic devices, rigidity of the projecting portion of the PAD was, to 
some extent, desirable. However, rigidity of the projecting portion of the 
PAD made it more likely that tearing of the bond between the PAD and 
dermal layer would occur if the projecting portion of the PAD or external 
leads connected to it were inadvertently struck or displaced relative to 
the skin as by an involuntary movement of the patient. 
Forming of the projecting portion of the PAD of a relatively soft, 
resilient material was not thought practical for several reasons. First, 
suitable biocompatible materials of sufficient softness and resiliency, if 
constructed as the sleeve of the PAD of U.S. Pat. No. 4,634,422, would be 
extremely difficult to handle and manipulate after the dermal layer cell 
had been cultured on the sleeve, particularly in the step of assembling 
the sleeve upon the PAD. Second, such materials were found to be very 
poorly adapted to the formation of microscopic pores of the desired 
diameter, depth and density, at least by economically feasible techniques. 
Third, construction of the PAD as a one-piece member, to avoid the first 
problem referred to above, seemed to require the culturing of a dermal 
layer over a far larger area of the PAD than would be necessary. 
The present invention is directed to a PAD especially designed to be 
constructed from a soft, resilient material upon which microscopic pores 
for bonding a layer of dermal cells to the external surface of the PAD may 
be formed over a minimum area no larger than that essentially required. 
The PAD is also constructed to minimize displacement of the PAD relative 
to the patient's skin by movement of external leads or conduits connected 
to or passing through the PAD. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a PAD is constructed from a body 
of a relatively soft, resilient, biocompatible material, such as silicone. 
The PAD body is formed as a one-piece member having a horizontally 
disposed, disc-like base flange with an integral projection projecting 
upwardly from a central location at the top of the base flange. A vertical 
bore extends downwardly entirely through the projection and base flange, 
and an elongate flexible tube of an outer diameter less than that of the 
inner diameter of the bore through the body passes through and projects 
from both the top and bottom of the bore. The tube is bonded to the body 
at the bottom of the bore so that the portion of the tube which extends 
through the projection is spaced from the side walls of the upper portion 
of the bore. 
The projection is provided with a coating of a copolymer of silicone and 
polycarbonate, this coating being susceptible to the formation of 
microscopic bores by the nuclear bombardment and etching technique 
described in U.S. Pat. No. 4,634,422. 
The flexible tube provides a through-the-skin passage which may be employed 
either as a fluid conducting passage to introduce or withdraw fluids from 
the patient's body or may constitute a passage through which electrical 
leads, wire guided instruments, etc. may be passed. By extending the tube 
for some distance from the projecting portion of the implanted PAD, and 
anchoring the tube end to the patient's body, forces applied during the 
connection or disconnection of external devices may be isolated from the 
PAD. 
The copolymer coating of the PAD provides a base upon which a coating of 
dermal cells may be cultured by the techniques described in U.S. Pat. No. 
4,634,422, using a culture and transport chamber of the type described in 
U.S. application Ser. No. 07/116/311 filed Nov. 4, 1987. 
Other objects and features of the invention will become apparent by 
reference to the following specification and to the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The PAD disclosed in the drawing includes a one-piece molded body 
designated generally 10 of a relatively soft, flexible and resilient 
biocompatible silicone material formed with a disc-like base flange 12. An 
integral, upwardly extending projection 14 is formed at a central location 
on base flange 12 and projects upwardly from flange 12. A vertical central 
passage or bore 16 extends downwardly through body 10 from the upper end 
of projection 14 through the bottom of base flange 12. An elongate 
flexible tube 18, which may also be of a suitable biocompatible silicone, 
extends coaxially entirely through central passage 16 and is permanently 
bonded to body 10 by a suitable bonding material 20 at the lower end of 
passage 16. As best seen in FIG. 2, the outer diameter of tube 18 is 
substantially less than the inner diameter of passage 16 so that a 
clearance exists between the tube and passage throughout substantially the 
entire portion of the tube within projection 14. 
The exterior surfaces of base flange 12 are covered by a layer of Dacron 
velour material, as at 22, 24. Suitable material for this purpose is 
commercially available. When the PAD is implanted in a patient, base 
flange 12 is disposed beneath the skin and the fibrous textured surface of 
the velour provides a surface into which body tissues may grow and 
interlock to stabilize the PAD. 
A coating of a silicone-polycarbonate copolymer is bonded to the outer side 
of projection 14. The polycarbonate component of this copolymer provides a 
surface which can be indented with a multitude of microscopic pores by a 
nuclear bombardment and etching process as described in U.S. Pat. No. 
4,634,422. As described in greater detail in that patent, the microscopic 
pores provide a surface into which dermal cells can grow to form a 
multicell layer of dermal cells mechanically bonded to the PAD. Culture 
and transport devices, such as those disclosed in U.S. patent application 
Ser. No. 07/116,311, permit the culturing of cells on the microporous 
surface of band 26. 
Referring particularly to FIG. 2, when implanted in the patient, the base 
flange 12 of the PAD underlies the patient's skin indicated in broken line 
at S, while the projection 14 of the PAD projects outwardly from the skin. 
That portion of tube 18 which is implanted in the patient is implanted at 
the time of implantation of the PAD. The external portion of tube 18, only 
a portion of which is shown, may be of whatever length is desired. The 
tube forms a conduit for the passage of fluid, electric leads, guide 
wires, etc., dependant upon the application. Couplings or electrical 
connectors may be mounted at the external end of tube 18 at some distance 
from the PAD itself, thereby effectively isolating the PAD from any 
disturbance during the connecting or disconnecting of connectors or 
couplings. As indicated in FIG. 2, the projection 14 is of tapered cross 
section which narrows toward its open outer end to provide a progressively 
decreasing resistance to flexing movement as indicated in broken line in 
FIG. 2 in the event the external portion of the tube might be 
inadvertently laterally displaced. 
While one embodiment of the invention has been described in detail, it will 
be apparent to those skilled in the art the disclosed embodiment may be 
modified. Therefore, the foregoing description is to be considered 
exemplary rather than limiting, and the true scope of the invention is 
that defined in the following claims.