Surgery – Instruments – Electrical application
Reexamination Certificate
1999-09-20
2001-11-06
Cohen, Lee (Department: 3739)
Surgery
Instruments
Electrical application
C606S046000, C606S048000, C606S051000, C606S170000, C606S174000
Reexamination Certificate
active
06312430
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to endoscopic surgical instruments, and more particularly to instruments known as end effectors which may include cutters or scissors, graspers and dissectors which are useful in laparoscopic or endoscopic procedures. The surgical instruments made according to the present invention are bipolar to permit safe and effective dissection, incising and cauterization of blood vessels, bleeding tissues, or non-bleeding tissues.
The use of heat for the cauterization of bleeding wounds dates back for centuries. More recently, the use of radio frequency (RF) electrical current traveling through a portion of the body has been widely used to stop bleeding. The RF energy cauterizes the blood by heating the blood proteins to a temperature where those proteins congeal similarly to the process involved in the cooking of egg whites. RF energy is preferred because its frequency is above that which could otherwise cause neuromuscular stimulation. The most frequently used modes of RF cauterization are monopolar and bipolar coagulation.
In monopolar coagulation, an active electrode is applied to a bleeding site and the electrical current flows from the electrode through the patient's body to a return electrode which may be a conductive plate in electrical contact with a large surface area of the patient's body such as the buttocks or thigh. One technique in which the monopolar mode may be employed involves fulguration which is the use of a spark or arc from the active electrode to the tissue.
Bipolar devices include both the active and return electrodes. Thus the electrical current flows down the surgical instrument to the active electrode and typically crosses a space on the order of millimeters, or shorter, to the return electrode and returns through the surgical device. Because no external return electrode is required, bipolar electrical surgical devices have the inherent advantage of containing the RF energy in a defined area. This prevents potential patient complications related to monopolar RF energy traveling through the patient's body, such as the burning of nearby tissue or affecting the neurological function. The reduction of patient complications is also accomplished because bipolar devices typically require less RF energy than equivalent monopolar devices.
Endoscopic surgical instruments, such as the bipolar electrosurgical end effectors are often used in laparoscopic surgery, which is most commonly employed for cholecystectomies (gall bladder surgeries), hysterectomies, appendectomies, and hernia repair. These surgeries are generally initiated with the introduction of a Veress needle into the patient's abdominal cavity. The Veress needle has a stylet which permits the introduction of gas into the abdominal cavity. After the Veress needle is properly inserted, it is connected to a gas source and the abdominal cavity is insufflated to an approximate abdominal pressure of 15 mm Hg. By insufflating the abdominal cavity, a pneumoperitoneum is created separating the wall of the body cavity from the internal organs. A surgical trocar is then used to puncture the body cavity. The piercing tip or obturator of the trocar is inserted through the cannula or sheath and the cannula partially enters the body cavity through the incision made by the trocar. The obturator can then be removed from the cannula and an elongated endoscope or camera may be inserted through the cannula to view the body cavity, or surgical instruments such as bipolar electrosurgical end effectors according to the present invention, may be inserted to perform the desired procedure.
Frequently an operation using trocars will require three or four punctures so that separate cannula are available for the variety of surgical instruments which may be required to complete a particular procedure. As described in U.S. Pat. No. 5,258,006 for bipolar electrosurgical forceps, the alternatives to bipolar cauterization or coagulation have been unacceptable. Monopolar instruments, using RF energy, often require greater current and provide unpredictabilities in current flow which may have a destructive effect on tissues surrounding the area to be cauterized.
While non-contact positioning of a laser may overcome this shortcoming, the laser has no way of holding a bleeding vessel and is not used on large bleeders. Laser based cauterization instruments remain expensive and unsuitable for tissue dissection techniques other than cauterization, such as blunt dissection or sharp dissection. Laser cauterization instruments suffer from the additional shortcomings that it is difficult to control the depth of penetration of the laser energy and that non-contact positioning of a laser can permit the laser beam to reflect off of other instruments and cause damage to surrounding tissue.
Furthermore, as described in U.S. Pat. No. 5,472,443 for an electrosurgical apparatus, there have been difficulties in bipolar instruments in two primary areas. The first is the difficulty in preventing excessive trauma or charring to the tissue being cauterized. Such charring or tissue damage can impede healing and regrowth of tissue. In addition, bipolar instruments suffer from a buildup of coagulated blood or severed tissue. In prior art instruments, such buildup impeded the effectiveness of the cauterization action of the instrument, and also tended to cause recently cauterized tissue to adhere to the coagulated blood and tissue on the instrument resulting in tears and reopening of blood flows along the cut or incision. The invention described herein overcomes these shortcomings and may effectively reduce the number of surgical instruments required for a given procedure.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide an improved surgical instrument with bipolar end effectors.
A further object of the invention is to provide an embodiment having two metal end effectors which are insulated except along portions for intended current travel.
Another object of the invention is to provide an embodiment having insulation on the back of at least one or both blades to prevent, or at least reduce current flow outside an intended current path.
It is a further object of at least one embodiment to pass current through the conducting strip of one end effector so that the coagulation caused by the RF energy tends to be very slightly in advance of or at the cutting point between the second and first end effectors, rather than rearward of the cutting point.
It is yet a further object of the invention to provide a bipolar instrument which utilizes RF energy more efficiently to cauterize tissue and thereby minimize charring of tissue.
Still, another object of the invention is to provide at least one notched blade which is believed to assist in providing tampon pressure at or near the intended severance path and assist in the defining of a more precise current travel path.
It is still a further object to provide an embodiment with two blades with corresponding notched portions which is believed to assist in providing tampon pressure and assist in the defining of a more precise current travel path.
Another object of the invention is to utilize electrodes in notched areas of the blades to focus the flow of current in the locale of the incision. This construction has been found to result in a greater current density in the incision by allowing RF current to flow directly through the incision instead of indirectly such that a stray current which may otherwise damage collateral tissue is significantly reduced.
These and other objects of the invention are accomplished by the utilization of one blade having a current conduit proceeding toward the distal end of the blade and therein connecting a conductive strip which proceeds rearward adjacent to the cutting surface of the blade. This blade is utilized to cut tissue in conjunction with a second blade. The second blade may, or may not, be similar in construction to the first blade, but the second blade will have a conducting strip capable
Danks John K.
Wilson Jeffrey A.
Young Jim
Cohen Lee
Endoscopic Concepts, Inc.
Johnson Douglas T.
Miller & Martin LLP
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