Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1999-06-15
2001-10-09
Seidel, Richard K. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S506000
Reexamination Certificate
active
06299609
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.
In addition to the procedural shortcomings described above, conventional treatments with antibiotics and other anti-microbial agents are undesirable because of the nature of the antibiotic and anti-microbial agents themselves. Many patients are allergic to antibiotics and other anti-microbial agents. Additionally, the repeated use of antibiotics to treat recurrent infections (of the type which would often be associated with implanted devices) can often lead to antibiotic resistance which, over time, can render further antibiotic treatments ineffective.
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 could use washing solutions which are free from antibiotics and/or other biologically active agents intended for killing the bacteria associated with an infection. It would be still firther desirable 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 bactericidal 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; 4,767,41 1; 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 treatment 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 a washing solution in an amount sufficient to flush a region within and/or surrounding the device. For prophylactic treatment, the washing solution may be any one of a variety of conventional washing solutions used for irrigation, lavage, and the like. Suitable washing solutions include saline, normal saline, and the like. While these solutions may include buffers, preservatives, and other conventional additives for washing solutions, they will generally be free from antibiotics and anti-microbial agents at a level which would have a microbicidal effect when administered to subcutaneous device sites according to the methods of the present invention.
For treatment of established infection, the washing solution will usually be the same, although in some cases the treatment may be supplemented with the systemic administration of an antibiotic, such as penicillin, vancomycin, and the like. The washing solution will be 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 0.5 ml to 1000 ml, often from 1.0 ml to 500 ml, more often from 2.0 ml to 100 and typically from 5.0 ml to 50 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 ability of the present invention to inhibit infection, either prophylactically or in the case of established infections, depends on the ability to flush the subcutaneously implanted device as well as the surrounding tissue, tissue pocket, and other sites where bacteria may accumulate and proliferate. Thus, it will generally be preferred to i
Brugger James M.
Burbank Jeffrey H.
Finch Charles D.
Wang John H.
Seidel Richard K.
Thissell Jeremy
Townsend and Townsend / and Crew LLP
Vasca, Inc.
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