Percutaneous Lead Device

Abstract

A percutaneous lead device including an element for preventing bacterial infection caused by implanting the lead through the skin. This element extends below and along the skin surface and includes an antibacterial fluid reservoir coated with a diffusion-controlling layer which maintains the desired fluid release rate. A surface configuration on the reservoir and lead which is highly adherent to and completely permeated by ingrowing tissue provides a particularly effective bacterial seal.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to method and means for preventing bacterial infection caused by implanting a percutaneous lead device in the skin and for achieving good fixation to minimize bacterial penetration and to avoid accidental removal of the lead.

Percutaneous lead devices such as tubes, shunts, cannulae, insulated wire, and various rods or tubular devices have been implanted through the skin for a wide variety of reasons. For example, such devices are used temporarily or over long periods of time to provide access to the circulated blood for blood pressure monitoring, blood sampling, the infusion of various substances, and the like. These lead devices are also used to connect external equipment to implanted devices, such as blood-flow probes, blood pumps, and pace makers. Two particularly widespread uses are as blood vessel connections in hemodialysis and as abdominal cavity access tubes for peritoneal dialysis. Both dialysis techniques are important tools in the treatment of kidney failure.

Although there is a substantial need for chronic, or long-term, use of percutaneous lead devices of the aforementioned type, the presently-available lead devices tend to cause infection by bacteria being transmitted across the skin and along the boundary between such devices and the surrounding skin tissue. Use of topical antibiotics at the skin puncture or the use of systemic antibiotics have been only marginally successful in the control of such infections since surface or systemic bacterial control does not prevent the eventual infection of the internal tissue. The only effective treatment of infections along present leads has been the removal of the lead and infected tissue, necessitating the implantation of a lead in a new site. Such untreated local infections will eventually result in systemic infections.

SUMMARY OF THE INVENTION AND OBJECTS

In accordance with the present invention, method and means are provided at a peripheral portion of a percutaneous lead device for releasing antibacterial fluid into the surrounding tissue at a controlled rate upon implanting the lead device into the skin. The release means includes a fluid reservoir, such as an absorptive material to which the antibacterial fluid is applied carried by a peripheral lead portion. In on embodiment, the coating material contains a plurality of microcavities which are compatible with blood and living tissue and form a tenacious base for anchoring tissue ingrowth which minimizes bacterial penetration along the lead surface.

It is a general object of the present invention to provide a method and means for preventing infection in a percutaneous lead device when implanted in the skin caused by bacteria being transmitted along the surface.

It is another object of the invention to provide a method and means for the controlled release of antibacterial fluid from the surface of a percutaneous lead device.

It is another object of the invention to provide a method and means for obtaining tissue fixation which avoids movement of the lead relative to adjacent tissue or accidental detachment or removal.

The foregoing and other objects will become apparent from the following description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is an enlarged view of a portion of skin and subcutaneous tissue together with a percutaneous lead device according to the invention; and

FIG. 2 is an enlarged view of the portion of FIG. 1 showing the release device of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawing, percutaneous lead line 10 in the form of a hollow tube is illustrated in an implanted position after penetration through skin 11 and subcutaneous tissue 12. Line 10 may also be a solid rod such as an insulated wire for monitoring purposes. Various uses for either type of percutaneous lead line are described hereinbefore. In one embodiment, line 10 includes an outer wall containing a plurality of microcavities 13, such as formed in accordance with the method set forth in the copending application Ser. No. 77,289, filed Oct. 1, 1970. These microcavities allow the skin and subcutaneous tissue to grow around the outside walls and become permanently fixed or anchored to the wall by tissue ingrowth.

As further disclosed in the aforementioned application, the lead wall material may be rigid or flexible, depending upon the particular use of the lead line. A flexible lead line has the desirable property of reducing surface shear forces as caused by body movement or external forces applied to the line.

An additional technique to increase surface area and reduce shear stresses as illustrated in FIG. 1 is the disposition of a subcutaneous portion of the lead line generally parallel to the skin surface. This additional length provides increased fixation as well as other advantages discussed below.

Tissue growth in the microcavities forms a generally sealing interface which effectively blocks the ingress of infection causing bacteria across the skin for prolonged periods of time. However, this tissue seal is not completed until growth of the surrounding tissue into all interstices of the microcavity surface structure takes place. Even though this seal is formed in a relatively short period of time (e.g., several days), it is necessary to prevent bacterial penetration into the tissue along the lead surface during seal formation. This protection is provided by the means described herein.

According to the invention, microcavity-containing lead lines achieve long-term use by antiseptically preventing early bacterial infections below the skin. For this purpose, (e.g., antibacterial fluid reservoir 14 is mounted onto peripheral lead portion 10a. To provide a slow release of the fluid so that it is available for a prolonged period of time, a diffusion-controlling layer in the form of coating 16 is mounted or applied to lead portion 10a over essentially the entire area of reservoir 14 so that the reservoir is sealed at its proximal and distal ends. In one embodiment, reservoir 14 is an antibacterial fluid containing a wick-like absorbant material such as porous cloth (e.g., knitted or woven Dacron) or a fibrous mat e.g., Teflon felt). The antibacterial agent is applied to the material and released at a controlled rate through the diffusion-controlling layer 16 into the skin.

In one embodiment of a diffusion-controlling layer 16 shown in the drawings, a plurality of elongated passages 17 are provided throughout the layer to promote the desired diffusion rate. Passages 17 may be formed in a similar manner to microcavities 13 or by physically puncturing or perforating the layer. Passages 17 may be supplemented by microcavities 18 of the same type as microcavities 13 throughout the coating in such a manner that they are linked with passages 17 to form paths through the coating of sufficient size and density to accomplish the desired diffusion properties. Microcavities 18 also serve to permit tissue ingrowth and adhesion to prevent bacterial penetration along the surface of the layer. In an example of one such coating, an average of about 100 penetrations per cm.sup.2 of 0.1 mm length and 0.05 mm width are positioned throughout the layer. A typical thickness for such a layer is 0.001 to 0.020 inch.

In another embodiment of a diffusion-controlling element (not shown), microcavity surface material may inherently possess the desired diffusion rate without the need for passages 17, as exemplified by Dacron cloth or a silicone rubber membrane layer.

The antibacterial fluid in reservoir 14 is of a type which is capable of allowing tissue growth on the outer surface of the percutaneous lead device while preventing bacterial infection. Suitable fluids include the following: maphenide acetate, silver nitrate, and silver sulfadiazine, and the like.

Antibiotic treatment is primarily beneficial from the time of implantation until tissue ingrowth occurs creating an effective bacterial seal at the tissue-microcavity surface. Thus, the antibiotic is supplied in amounts to be consumed at approximately that time.

The antibiotic treatment is maintained until complete tissue ingrowth and fixation occur, and may be discontinued at this time because an effective bacterial seal is created at the tissue-microcavity surface. If antibiotic treatment is discontinued, then means for preventing bacterial invasion of reservoir 14 are provided. These means include an impervious coating external to the skin (coating 18) which is either applied prior to implantation or at the time antibacterial treatment is stopped. If the reservoir is wholly beneath the surface of the skin, then no surface coating need be applied. In either case, the reservoir can be filled with an inert substance (curable silicon rubber, silicone grease) to prevent bacterial growth within the reservoir.

In general, it is noted that reservoir 14 may extend to any desired degree above the surface of the skin or therebelow. The reservoir may extend above the skin or may terminate just below the skin in the subcutaneous tissue as shown in FIG. 1.

After depletion of antibiotic, a pathway may be formed for bacteria through the porous coating 16 and empty reservoir 14 into the skin. To prevent this, it is preferred to terminate the reservoir and coating just below the skin in the subcutaneous tissue so that permeable layer 16 is not exposed. If it is desired to extend the reservoir above the skin, then the externally projecting portion of layer 16 should be rendered impermeable as by application of an impermeable coating prior to implantation or after termination of treatment.

Depletion of antibiotic fluid may also provide a site for bacteria growth in body fluids which diffuse through layer 16. This may be avoided by filling the depleted reservoir with an inert substance (e.g., curable silicone rubber or silicone grease) after antibiotic fluid depletion.

To form the antiseptic means for preventing infection according to the invention, the bacterial fluid is first supplied to reservoir 14 either before mounting layer 16 or thereafter as through a hypodermic needle penetrating the coating.

Claims

We claim:

1. A percutaneous device comprising an elongated lead adapted to penetrate the skin, said lead including a portion having an external surface compatible with skin, subcutaneous tissue and other tissue, said surface including pockets extending into said surface for receiving ingrowth of living cells to permanently anchor the lead, antiseptic means including an antibacterial fluid reservoir for providing a controlled release of said fluid adjacent said portion of the lead, said reservoir including a walled chamber attached to said lead, said chamber walls provided with diffusion controlling passage means so that upon penetration of the skin by the device the fluid is released directly from said reservoir into the area around said reservoir portion over a prolonged period of time to prevent bacterial penetration into the tissue along the lead during ingrowth of said cells.

2. A lead device as in claim 1 in which said reservoir comprises an antibacterial fluid-containing absorptive material carried within said chamber of the lead.

3. A percutaneous lead as in claim 2 in which said release means includes a permeable barrier covering said absorptive material.

4. A percutaneous lead device as in claim 3 in which said barrier is a layer extending over essentially the entire surface of the absorptive material.

5. A percutaneous lead device as in claim 4 in which said layer is covered by a material which is compatible with living tissue having a plurality of microcavities of predetermined size and shape.

6. A percutaneous lead device as in claim 4 in which said layer has a thickness of from 0.001 to 0.020 inch.

7. A percutaneous lead as in claim 4 in which said layer is capable of anchoring tissue ingrowth on its outer surface.

8. A percutaneous lead device as in claim 5 including elongated passages through said layer of a size sufficient for permeability.

9. A percutaneous device comprising an elongated hollow lead adapted to penetrate the skin, said lead including a portion having a flexible external surface compatible with skin, subcutaneous tissue and other tissue, said surface portion including a plurality of adjacent substantially discrete pockets having openings which face toward the tissue, the walls of said pocket being of such shape and size as to provide means to accommodate a number of living cells sufficient to provide anchoring but not so large as to prevent essentially normal transfer of nutrients to said living cells in said pockets from said adjacent area of tissue, antiseptic means including an antibacterial fluid reservoir for providing a controlled release of said fluid adjacent said portion of the lead, said reservoir including a walled chamber attached to said lead, said chamber walls provided with diffusion controlling passage means so that upon penetration of the skin by the device the fluid is released directly from said reservoir into the area around said reservoir portion over a prolonged period of time to prevent bacterial penetration into the tissue along the lead during ingrowth of said cells.