Surgery – Instruments – Electrical application
Reexamination Certificate
1998-10-23
2001-08-21
Dvorak, Linda C. M. (Department: 3739)
Surgery
Instruments
Electrical application
C606S051000, C606S052000
Reexamination Certificate
active
06277117
ABSTRACT:
BACKGROUND
The present disclosure relates to electrosurgical forceps used for open surgical procedures. More particularly, the present disclosure relates to a bipolar forceps having a disposable electrode assembly for sealing, cauterizing, coagulating/desiccating and/or cutting vessels and vascular tissue.
TECHNICAL FIELD
A hemostat or forceps is a simple plier-like tool which uses mechanical action between its jaws to constrict tissue and is commonly used in open surgical procedures to grasp, dissect and/or clamp tissue. Electrosurgical forceps utilize both mechanical clamping action and electrical energy to effect hemostasis by heating the tissue and blood vessels to coagulate, cauterize, cut and/or seal tissue.
By utilizing an electrosurgical forceps, a surgeon can either cauterize, coagulate/desiccate and/or cut tissue and/or simply reduce or slow bleeding, by controlling the intensity, frequency and duration of the electrosurgical energy applied to the tissue. Generally, the electrical configuration of electrosurgical forceps can be categorized in two classifications: 1) monopolar electrosurgical forceps; and 2) bipolar electrosurgical forceps.
Monopolar forceps utilize one active electrode associated with the clamping end effector and a remote patient return electrode or pad which is attached externally to the patient. When the electrosurgical energy is applied, the energy travels from the active electrode, to the surgical site, through the patient and to the return electrode.
Bipolar electrosurgical forceps utilize two generally opposing electrodes which are disposed on the inner opposing surfaces of end effectors and which are both electrically coupled to an electrosurgical generator. Each electrode is charged to a different electric potential. Since tissue is a conductor of electrical energy, when the effectors are utilized to clamp or grasp tissue therebetween, the electrical energy can be selectively transferred through the tissue.
The process of coagulating small vessels is fundamentally different than vessel sealing. For the purposes herein the term coagulation is defined as a process of desiccating tissue wherein the tissue cells are ruptured and dried. Vessel sealing is defined as the process of liquefying the collagen in the tissue so that it crosslinks and reforms into a fused mass. Thus, coagulation of small vessels is sufficient to close them, however, larger vessels need to be sealed to assure permanent closure.
In order to effect a proper seal with larger vessels, two predominant mechanical parameters must be accurately controlled—the pressure applied to the vessel and the gap between the electrodes both of which affect thickness of the sealed vessel. More particularly, accurate application of the pressure is important to oppose the walls of the vessel, to reduce the tissue impedance to a low enough value that allows enough electrosurgical energy through the tissue, to overcome the forces of expansion during tissue heating and to contribute to the end tissue thickness which is an indication of a good seal. In some instances a fused vessel wall is optimum between 0.001 and 0.006 inches. Below this range, the seal may shred or tear and above this range the lumens may not be properly or effectively sealed.
Numerous bipolar electrosurgical forceps have been proposed in the past for various open surgical procedures. However, some of these designs may not provide uniformly reproducible pressure to the blood vessel and may result in an ineffective or non-uniform seal. For example, U.S. Pat. No. 2,176,479 to Willis, U.S. Pat. No. 4,005,714 to Hiltebrandt, U.S. Pat. Nos. 4,370,980, 4,552,143, 5,026,370 and 5,116,332 to Lottick, U.S. Pat. No. 5,443,463 to Stern et al., U.S. Pat. No. 5,484,436 to Eggers et al., all relate to electrosurgical instruments for coagulating, cutting and/or sealing vessels or tissue.
These instruments rely on clamping pressure alone to procure proper sealing thickness and are not designed to take into account gap tolerances and/or parallelism and flatness requirements which are parameters which, if properly controlled, can assure a consistent and effective tissue seal. For example, it is known that it is difficult to adequately control thickness of the resulting sealed tissue by controlling clamping pressure alone for either of two reasons: 1) if too much force is applied, there is a possibility that the two poles will touch and energy will not be transferred through the tissue resulting in an ineffective seal; or 2) if too low a force is applied, a thicker less reliable seal is created.
It has also been found that cleaning and sterilizing many of the prior art bipolar instruments is often impractical as electrodes and/or insulation can be damaged. More particularly, it is known that electrically insulative materials, such as plastics, can be damaged or compromised by repeated sterilization cycles.
Thus, a need exists to develop a bipolar forceps which can seal vessels and tissue consistently and effectively and which will not be damaged by continued use and cleaning.
SUMMARY
The present disclosure relates to a removable electrode assembly for use in combination with a mechanical forceps having opposed end effectors and a handle for controlling movement of the end effectors relative to one another. The electrode assembly includes a housing which is removably engageable with the mechanical forceps and a pair of electrodes which are attachable to a distal end of the housing. The electrodes are removably engageable with the end effectors of the mechanical forceps such that the electrodes reside in opposing relation relative to one another.
Preferably, the distal end of the housing is bifurcated forming two prongs and each of the electrodes is attached to each of the prongs. In one embodiment, the prongs are movable relative to one another to facilitate engagement of the electrodes with the end effectors of the mechanical forceps.
Each electrode preferably includes an electrically conductive sealing surface and an insulating substrate. The substrate includes at least one mechanical interface for engaging a complimentary mechanical interface disposed on the corresponding end effector of the mechanical forceps. In one embodiment the electrodes include at least one guide pin and the corresponding end effector includes a complimentary aperture for receiving the guide pin.
Preferably, the electrode assembly includes at least one stop member for controlling the distance between the opposing electrodes. In another embodiment of the present disclosure, the mechanical forceps includes at least one stop member for controlling the distance between the end effectors which, in turn, control the distance between the attached opposing electrodes.
Another embodiment of the present disclosure includes a cover plate which is removably engageable with the housing member and the mechanical forceps are disposed between the housing and the cover plate when the bipolar forceps is assembled.
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Buysse Steven Paul
Lawes Kate Ryland
Schmaltz Dale Francis
Tetzlaff Philip Mark
Dvorak Linda C. M.
Kearney R.
Sherwood Services AG
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