Surgery – Instruments – Electrical application
Reexamination Certificate
1999-02-11
2001-01-16
Peffley, Michael (Department: 3739)
Surgery
Instruments
Electrical application
C606S051000, C606S052000
Reexamination Certificate
active
06174309
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to surgery and particularly to electrosurgical devices.
In general when performing any surgery the surgeon must be attentive to the presence of blood vessels in the tissue being cut. Depending on the circumstances, vessels may be tied off at two positions before being severed, or if severed unknowingly, may be stapled, clipped, tied off and/or coagulated after cutting. Several surgical instruments address commonly arising situations, for example by providing dual rows of staples surrounding a cutting blade to simultaneously sever and close a vessel or tubular organ. Furthermore, electrocoagulation has been used to seal vessels and prevent the flow of blood when cut. However coagulation relies upon generation of heat in the tissue by current flowing therein, and the degree of coagulation results from a complex balance of tissue impedance, heat transfer due to contact, perfusion etc., and the area and energy of the applied RF coagulation source, all of which will affect the degree of coagulation and the time required for effective treatment. In addition to RF coagulation, RF scalpels have also come into wide use. These operate by providing a high current over a sharp edge or small area so that the contact electrode acts as a blade and cuts tissue along the blade path. The contact electrode for an RF scalpel may in fact be blade shaped, and also perform physical cutting, although in practice such scalpels have an edge of finite width to present a defined level of electrical power.
One would expect that since an electrosurgical scalpel and a coagulation unit each rely on the provision of RF energy, combined instruments would be readily available. There have in fact been instruments designed for both purposes, for example a spatula-like scalpel which is useful both for small cauterization and for cutting operations. In general however, for larger surgery, suturing or clipping of vessels is still required prior to cutting tissue or vessels. Thus, when operating in the mesentery, each vessel must be hand-tied in two places with sutures before a cut is made e.g., with scissors between the sutures, a tedious and time consuming process. One commercial product known as the “harmonic scalpel” marketed by Ethicon includes a blade and a coagulator arranged to simultaneously seal and cut sections of tissue and small vessels, thus providing an alternative to the suturing approach. However that device, configured for endoscopic use, is most suitable for procedures such as splenectomy, adrenalectomy, and breast biopsy. It operates rather slowly and its body gets quite warm during operation, raising a risk of damaging nearby tissue. Thus caution must be taken during use to avoid unintentional contact, and the practical length of the operating area is limited, making it unsuitable for many surgeries.
It would therefore be desirable to provide an electrosurgical scalpel and coagulator which operates in other tissue areas and which for example may be used to simultaneously cut and seal multiple vessels of the mesentery. It would further be desirable to provide such an instrument which coagulates quickly while producing little heat in the body of the instrument so that it may be used for prolonged periods in operation on major tissue structures such as the colon, small bowel, lungs, stomach or uterus, as well as smaller structures.
SUMMARY OF THE INVENTION
One or more of the foregoing problems are addressed and advantageous results achieved in an electrosurgical instrument having a handle and a body which position and close a jaw about a tissue site. The jaw includes an electrosurgical cutting member which is biased against a cut line, and an electrode-bearing clamping assembly that clamps a region adjacent the cut line so that the tissue next to the cut is immobilized and dependably sealed in coordination with the cutting procedure.
Preferably, the instrument has the shape of a hemostat with a pair of scissor-like arms defining upper and lower gripping jaws. The upper jaw has a longitudinally extending split or channel in which the electrosurgical cutter such as a blade or wire is positioned and the cutter is biased against an intended cut line extending in the plane gripped by the jaws. The lower jaw has two parallel RF common electrode surfaces, one positioned on each side of the cut line. The two arms of the instrument pivot on an insulating sleeve or bushing to maintain electrical separation therebetween, and the RF power for the cutting blade and the coagulation electrodes is provided through one arm so that all active power is exposed only at small regions at the jaw of that arm. The sealing electrodes are formed of an electrically conductive material, preferably of high thermal conductivity, which may be covered by a thinner coating or thermally non-impeding heat transfer cover, so that tissue in contact therewith is heated to sealing temperature without charring or sticking the tissue at an electrode interface. The coating or cover may include or further carry additional material to assure biocompatibility and to prevent charring and sticking. Preferably the cutting blade or wire is fabricated or coated with an electrically insulating dielectric away from its tissue contacting face, so that fluids which wick into the jaw gap or onto the blade do not introduce new current paths between electrodes, and thus cannot alter or reduce the blade's ability to apply a high energy density at a narrow line for cutting tissue.
The jaws of the device may be extended substantially forward of the blade, which is preferably biased in the direction of jaw closing so that it rides on the tissue. The blade may mount, for example at a slight angle, and can move slightly with respect to the jaw under the bias force, for example, of a leaf spring or a flexure at an anchored end thereof. Preferably, the blade and the sealing electrodes each receive a separate supply of RF energy, which is impedance matched to their particular size and energy transfer requirements. This may be provided by a pair of impedance-matching transformers configured for connection to a common RF source. Alternatively, a transformer having a secondary winding with multiple taps, or a transformer having multiple windings for current and voltage outputs may suitably apportion the total energy applied at the primary between the cutting and sealing electrodes so that each operates with a coordinated time interval to perform its intended task. The transformer or transformers may also have a plurality of taps on the primary side to adapt it for use with different electrosurgical console power supplies. Other power sources may include synthesized and switched circuits to provide RF waveforms of suitable characteristics, rather than such matching or apportioning transformers.
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United States Statutory Invention
Allaire Kevin M.
Frey William
Lemire Kevin
Nardella, Sr. Paul C.
Wrublewski Thomas A.
Medical & Scientific, Inc.
Nutter & McClennen & Fish LLP
Peffley Michael
LandOfFree
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