Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1998-01-07
2001-10-09
Mendez, Manuel (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S500000, C604S093010
Reexamination Certificate
active
06299610
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 disinfecting implanted devices and to modified devices which facilitate such disinfection 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 of surrounding tissue pockets. Subcutaneously implanted ports which are periodically accessed by needles and other percutaneously introduced devices are particularly subject to infections introduced by the access device.
Heretofore, infections of subcutaneously implanted devices have usually been treated by administering antibiotics to the patient after infection has become established. Most 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. 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 for inhibiting infection of subcutaneously and transcutaneously implanted devices. 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 surrounding the device within a pocket of tissue. 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. The agent will usually be 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 1 ml to 50 ml, more often from 2 ml to 25 ml, and typically from 2 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.
In a preferred aspect of the method of the present invention, the subcutaneously implanted device is a port which is connected to a blood vessel, other body lumen or cavity, or solid tissue target site, usually using a cannula. The port has an aperture for receiving a percutaneous access tube, e.g. a needle. The anti-microbial agent is injected directly into the aperture to both flush the aperture and any internal volume surrounding or in fluid communication with the aperture, with excess anti-microbial agent being flushed from the aperture to infuse a region or space surrounding the port within the tissue pocket in which the port has been implanted. Usually, the port will be valved to isolate the access aperture from that portion of the port which is connected to the cannula and/or the blood vessel or body lumen. Thus, flushing of the port with the anti-microbial agent can be performed without introduction of the agent beyond the valve, i.e. into the blood vessel or other target site. The needle used to flush the access port will be introduced in a manner which does not open the valve structure, thus maintaining isolation. The needle used to introduced the anti-microbial agent, however, will usually be introduced through the same site or tissue tract as the primary access tube, thus reducing patient trauma. The disinfecting needle will usually be smaller than the access tube, even further reducing patient trauma.
The methods of the present invention are also useful for disinfecting and inhibiting infection with ports and other subcutaneously implanted devices which do not have open access apertures. In such cases, it will usually be unnecessary to disinfect internal portions of the device, and the disinfecting needle can be contacted directly against an external surface of the device in order to infuse the anti-microbial agent within the tissue pocket surrounding the device. Optionally, the needle may be contacted against a specially configured target site on the device, e.g. a well or other region on the device composed of or lined with a relatively hard material that can withstand repeated contact with the disinfecting needle. The well or other target can be located by the treating professional, e.g. by manually feeling it through the skin, and will be positioned to permit the anti-microbial agent to infuse freely about the exterior of the device at the interface between the device and the tissue. In some cases, it may be desirable to connect the well to channels or other surface features which permit the anti-microbial agent to suffuse freely around the periphery of the device.
In yet another embodiment, the methods may be used to disinfect transcutaneously implanted devices, such as catheters. In such cases, the disinfectant is infused into the tissue pocket formed about the device, usually by inj
Brugger James M.
Burbank Jeffrey H.
Finch Charles D.
Wang John H.
Gring Kent
Mendez Manuel
Townsend and Townsend / and Crew LLP
Vasca, Inc.
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