Surgery – Instruments
Reexamination Certificate
1999-11-29
2002-09-10
Peffley, Michael (Department: 3732)
Surgery
Instruments
C606S041000, C606S046000
Reexamination Certificate
active
06447502
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a protective cap for medical HF instruments.
HF (high-frequency) instruments are commonly known, and are presented, for example, in the catalog of the company styled Karl Storz GmbH & Co., “Endoskopische Chirurgiell” [Endoscopic surgery], Section 6, 2nd ed. 1/94.
HF instruments are used for high-frequency coagulation or for high-frequency cutting.
High-frequency coagulation is used for surgical destruction of tissue areas, for hemostasis, to remove portions of tissue, or for thermal coagulation of tumors.
High-frequency cutting can be performed with HF instruments of the same design as for high-frequency coagulation high-frequency cutting is used, for example, to remove cysts, to cut through vessels, or for similar surgical interventions.
For use in the widely practiced technique of minimally invasive surgery, HF instruments are configured as tubular-shaft instruments.
Tubular-shaft instruments comprise a proximal handle and a shaft, joined immovably or detachably thereto, that is configured as a tubular shaft. Guided through this tubular shaft is a working insert that, at its distal end, projects beyond the shaft and carries the actual working device, for example a needle-shaped electrode or the mouth parts of a cutting or grasping tool.
The current to be applied is delivered via a high-frequency cable from a high-frequency generator arranged remotely from the HF instrument. For electrical connection to the instrument, a connector is provided on it. This connector usually comprises a metal pin mounted on the handle of the instrument and protruding from it.
The connector is in electrical contact with the actual working device, so that the current is guided through it to the distal end.
Whereas the connector for the high-frequency cable is generally immovably joined to the HF instrument, the generator is connected to the HF instrument, via the cable, only as necessary.
A distinction is made between unipolar and bipolar HF instruments, depending on the type of current delivery.
In a unipolar (also called monopolar) HF instrument, a connector for only one pole is provided on the instrument. The patient lies on an electrically conductive mat that constitutes the second pole. The current emerging from the distal end of the unipolar HF instrument flows over a large area through the patient's body to the conductive mat.
In bipolar HF instruments, two connectors are present on the instrument, i.e. the current is fed in at the proximal end, delivered to a tool (e.g. a coagulation loop) at the distal end, then returned back to the proximal end and there discharged.
The term “connector” hereinafter comprises, in the case of mono- or unipolar HF instruments one connector, and in the case of bipolar HF instruments two connectors or connector plugs.
It has been found in practical use that electrical arcs can occur in the region of the connector plug, resulting in jerky reactions on the part of the surgeon. Adverse effects can also result from leakage currents.
A variety of solutions have hitherto been proposed for protecting the surgeon from such adverse effects.
For example the aforementioned catalog of Karl Storz GmbH & Co. shows, in Section 5 on page SCT 5/1 A, a handle for a tubular-shaft instrument having a connector for a unipolar high-frequency cable, in which insulation is achieved by the fact that the handle is made substantially of nonconductive plastic. Only the connector pin is made of metal, and is insert molded into the plastic. The handle has one fixed and one movable handle element, which can be moved relative to one another by way of a hinge joint made of plastic.
This type of insulation has the disadvantage that the handles do not exhibit sufficient mechanical stability.
The plastic hinge that was used could not withstand the mechanical stresses.
The pivot pins were therefore once again made of metal.
Since, however, the joints are located in close proximity to the connector for the high-frequency cable, the risk once again exists of voltage arcing or leakage currents from the connector to the metal hinge pin.
Because of the poor mechanical stability of plastic handle elements for HF instruments, it was alternatively proposed to utilize metal parts and to cover them with an electrically insulating plastic coating.
These coatings have not, however, proven durable over the long term. Handling, especially during cleaning and autoclaving, creates the risk that the coating can become damaged and can detach, and thereby expose metal areas of the instrument. In particular, a coating can exhibit less than complete coverage in areas where moving parts make contact with one another, for example at joints. This can result in arcs or leakage currents during HF use.
The purpose of the handle at the proximal end of the instrument, on which the connector for the high-frequency cable is present, is to control the distal end of the working device, e.g. spreadable mouth parts, extending through the tubular shaft.
For this purpose, an actuation element, usually in the form of a rod, projects proximally beyond the tubular shaft and is joined to a movable handle element of the handle. When the handles are, as is usual, scissor-like, one end of the handle element that is movable (i.e. pivotable) about the hinge axis is mechanically connected to the proximal end of the actuation element projecting beyond the tubular shaft, in order to convert a pivoting movement of the handle element into a linear displacement movement of the rod-shaped actuation element.
Ball-and-socket joints have proven successful as the mechanical connection, especially for instruments that can be disassembled. The usually solid, proximally projecting end of the metal actuation element is located, depending on the design, in the vicinity of the connector for the HF cable, and during HF operation also constitutes an exit point for arcs. Even insulation of this area cannot provide a remedy, since any insulation would soon be rubbed off by the frictional ball-and-socket mechanism.
With bipolar HF instruments, there exists the additional risk of arcing from the connector plug of the one pole to the connector plug of the other pole.
Against this background, it is the object of the present invention to create a reliable insulation system for HF instruments that does not adversely affect the stability and functionality of the other components of the HF instrument.
SUMMARY OF THE INVENTION
According to the present invention, the object is achieved by a protective cap which is configured such that it covers the instrument in insulating fashion at least in the vicinity of an electrical connector for a high-frequency cable.
This object is furthermore achieved by a medical HF instrument that has a protective cap of this kind.
The provision of an insulating protective cap eliminates the absolute necessity either for the HF instrument, or at least those regions of the HF instrument in which the connector for the high-frequency cable is located, to be produced entirely from insulating material; or, in the case of metallic materials, for them to be completely equipped with an insulating covering. For example, the handle including its joint and the connector for the high-frequency cable can be produced from metal, and nevertheless protected, in optimally electrically insulating fashion, against arcing once the protective cap has been attached. The protective cap thus makes it possible to manufacture those components that contain the electrical connector from mechanically stable and resistant material. Since the protective cap covers at least the vicinity of the electrical connector in insulating fashion, the danger of arcing or leakage currents to conductive elements and thus to the surgeon is eliminated. The electrical connector as such is, of course, electrically insulated with respect to the handles.
Depending on whether the instrument is configured as a unipolar or bipolar instrument, one connector plug or two connector plugs and their vicinity are covered in in
Bacher Uwe
Dittrich Horst
Karl Storz GmbH & Co. KG
Peffley Michael
St. Onge Steward Johnston & Reens LLC
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