Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1998-09-25
2002-08-20
Seidel, Richard K. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S502000
Reexamination Certificate
active
06436084
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to medical devices and methods. More particularly, the present invention relates to methods for inhibiting and treating the infection of implanted devices and to modified devices which facilitate such methods.
Subcutaneously and transcutaneously implanted devices are utilized for a wide variety of purposes. Heart pacemakers have become commonplace. Transvascular catheters are used for a variety of purposes, including hemodialysis access, drug infusion, and the like. Of particular interest to the present invention, subcutaneously and transcutaneously implanted ports and catheters have been proposed for both drug infusion and hemodialysis access. All such implanted devices are subject to infection. Subcutaneously implanted ports which are periodically accessed by needles and other percutaneously introduced devices are particularly subject to infections introduced by the access device.
Most infections of subcutaneously implanted ports begin as bacteria from the skin are carried into the tissue tract and port by the needle penetration. An infection can then grow internal to the port or within the tissue “pocket” which surrounds the port. A tissue pocket will form when the exterior surface of the port or other device is impermeable to tissue in-growth, e.g. where the surface is hard and composed of a metal, such as stainless steel, titanium, plastic, or the like. Infection can enter the space between the external surface of the device and the opposed tissue surface and can spread throughout the tissue pocket and sometimes into adjacent spaces, e.g. the space around a cannula attached to the port and leading to a blood vessel or other body lumen. While initially localized, the infection can become systemic and place the patient at significant risk.
Heretofore, infections of subcutaneously implanted devices have usually been treated by the systemic administration of antibiotics to the patient after infection has become established. Often, the implanted device must also be removed and replaced, subjecting the patient to additional trauma and leaving the patient without benefit of the device for the time it takes to clear the infection and replace the device. Moreover, the need to administer antibiotics periodically to patients is expensive and patients who suffer from repeated infections often become resistant to particular antibiotics.
As an alternative to antibiotic treatment and/or device removal, U.S. Pat. No. 5,263,930 proposes to provide a disinfectant reservoir in an implantable vascular access port. The reservoir includes a septum to permit periodic replenishment with a suitable anti-microbial agent. Agent introduced into the reservoir flows into an access lumen through the device. Catheters and other devices inserted into the access lumen become coated with the anti-microbial agent to provide a barrier against infection along the percutaneous access route. In particular, the design is intended to prevent infection of the bloodstream. While potentially beneficial, the provision of a static volume of anti-microbial agent within a reservoir does not provide flushing and active decontamination of the tissue pocket surrounding the implanted port. Thus, should bacteria be introduced into the tissue pocket, it is unlikely that the anti-microbial agent would be effective to inhibit infection.
For these reasons, it would be desirable to provide improved methods and devices for inhibiting bacterial and other infections in subcutaneously implanted devices. It would be particularly desirable to provide methods and devices for active flushing of the implanted device as well as the tissue pockets and regions surrounding the device in order to maximize the disinfection process. It would be particularly useful if such methods and devices were applicable not only to implantable ports but also to other subcutaneously and transcutaneously implanted devices. At least some of these objectives will be met by the present invention as described hereinafter.
2. Description of the Background Art
U.S. Pat. No. 5,263,930 has been described above. A transcutaneous vascular access port sold under the tradename HEMASITE® II by Renal Systems, Inc., Minneapolis, Minn., includes an above-skin reservoir for a bactericide, as described in a brochure entitled Vascular Access System copyrighted by the manufacturer in 1984. Catheters having bacteriocidal coatings and release capabilities are described in U.S. Pat. Nos. 5,599,321; 5,591,145; 5,482,740; 5,261,896; 5,236,422; 5,004,455; 4,959,054; 4,767,411; and 4,579,554.
SUMMARY OF THE INVENTION
The present invention provides methods and improved apparatus systems, and kits for inhibiting and/or treating infection of subcutaneously and transcutaneously implanted devices. As used hereinafter, the phrase “inhibiting infection” will refer to both prophylactic treatment to avoid infection and therapeutic treatment to eliminate an established infection. The methods and apparatus are particularly applicable to disinfection of implanted vascular and other access ports which are at substantial risk of infection through repeated percutaneous access via needles, access cannulas, stylets, and the like. The present invention, however, will also be useful with a variety of other subcutaneously implanted devices, including pacemakers, catheters, prosthetic joints, defibrillators, implantable infusion pumps, and the like.
The present invention relies on percutaneous injection of an anti-microbial agent in an amount sufficient to infuse a region within and/or surrounding the device. For prophylactic treatment, the anti-microbial agent may be any one of a variety of conventional bactericidal, fungicidal, virucidal, or other disinfecting agents, typically being selected from the group consisting of sodium hypochlorite, calcium hypochlorite, sodium oxychlorosone, alcohols, aldehydes, halides, providone iodine, peroxides, and the like. For treatment of established infection, the anti-microbial agent will usually be the same, and the treatment may be supplemented with the systemic administration of an antibiotic, such as penicillin, vancomycin, and the like. The anti-microbial agent will flowable so that it can be percutaneously introduced to the implanted device, usually being in the form of a liquid, although it could also be a flowable gel, and will usually be injected at a volume in the range from about 0.05 ml to 50 ml, often from 0.1 ml to 25 ml, more often from 0.5 ml to 25 ml, and typically from 0.5 ml to 10 ml. Injection will conveniently be effected using a needle which can be penetrated directly through the skin, typically in combination with a conventional syringe.
The extent and nature of the region which is irrigated or flushed will depend greatly on the geometry and type of the implanted device. For implanted devices having internal spaces, such as implanted ports having apertures for receiving percutaneous access tubes, it will usually be desirable to infuse and flush at least the internal space with the anti-microbial agent. Preferably, at least a portion of any tissue pocket surrounding the implanted device will also be infused and flushed with the anti-microbial agent. More preferably, a sufficient amount of the anti-microbial agent will be introduced to flush outwardly through the access tissue tract which is used to introduce the flushing needle and/or to subsequently introduce an access tube. In particular, the present invention is able to disinfect the tissue tract used for subsequently introducing an access tube and to leave a sufficient amount of anti-microbial agent to disinfect any bacteria which are on the access tube when it is later introduced.
For transcutaneously implanted device, i.e. devices which pass through an access site in the patient's skin (such as transcutaneous catheters), the anti-microbial agent is preferably introduced at a site just proximal to an infection barrier, such as an infection-inhibiting cuff on the catheter. In this way, the anti-
Brugger James M.
Burbank Jeffrey H.
Finch Charles David
Wang John H.
Seidel Richard K.
Thissell Jeremy
Townsend and Townsend / and Crew LLP
VASCA, Inc.
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