Surgery – Instruments – Electrical application
Reexamination Certificate
2000-03-01
2001-03-27
Cohen, Lee (Department: 3739)
Surgery
Instruments
Electrical application
C606S048000, C606S049000, C606S051000
Reexamination Certificate
active
06206876
ABSTRACT:
BACKGROUND OF THE INVENTION
Electrosurgery is commonly used to cauterize, cut and/or coagulate tissue. In typical electrosurgical devices, RF electrical energy is applied to the tissue being treated. Local heating of the tissue occurs, and, depending upon the waveform of the applied energy, the desired effect is achieved. By varying the power output and the type of electrical waveform, it is possible to control the extent of heating and, thus, the resulting surgical effect. For example, a continuous sinusoidal waveform is best suited for cutting, while a waveform having periodically spaced bursts of a partially rectified signal produces coagulation.
In bipolar electrosurgery, the electrosurgical device includes two electrodes. The tissue being treated is placed between the electrodes, and the electrical energy is applied across the electrodes. In monopolar electrosurgery, the electrical excitation energy is applied to a single electrode at the surgical site, and a grounding pad is placed in contact with the patient. The energy passes from the single monopolar electrode through the tissue to the grounding pad.
While tissue heating is the mechanism by which the various surgical treatments are realized, it can also cause various obstacles to optimum procedure performance. For example, the heat causes tissue fluids to evaporate. As the tissue is desiccated, the electrical resistance of the tissue increases, making it increasingly more difficult to supply adequate power to the tissue. Eventually, the resistance rises to such a high level that it is impossible to continue the procedure. This is such a well-known and common problem in prior electrosurgical devices that surgeons have become accustomed to it and have tailored their procedures to minimize its effects. Typically, surgeons operate prior electrosurgical devices at a very low power level. This prevents the electrode and the adjacent tissue from becoming too hot too fast. Unfortunately, it also requires the surgeon to perform the procedure much more slowly than he would if he could operate the device at full power. As a result, the procedure takes much longer, requiring more operating room time and longer exposure of the patient to dangerous anesthetics.
Heating also causes charring of the tissue. Like desiccated tissue, charred tissue is of very high resistance. Therefore, as the surface of the tissue being treated becomes charred, it becomes difficult, and eventually impossible, to continue delivering power to the tissue as desired. Once again, to avoid the problem, surgeons perform procedures much more slowly than is desirable.
Electrosurgical procedures are also hindered by adherence of tissue to heated electrodes. During electrosurgery, the heated tissue tends to transfer heat to the electrodes. As an electrode becomes hot, tissue tends to stick to it, resulting in various complications. First, the tissue stuck to the electrode can have a high resistance and can therefore hinder delivery of power to the tissue. In prior devices, while performing a procedure, a surgeon must periodically remove the device from the patient and clean it before continuing. In addition, surgeons typically perform the procedure at low power to reduce tissue adherence and thus the frequency of cleanings.
Tissue sticking can also cause unnecessary bleeding. During electrosurgical procedures, the tissue being treated often heats the electrode such that, when the electrode is removed from the tissue, a portion of the tissue sticks to the electrode and is torn away, which likely results in bleeding. Thus, as the surgeon is attempting to cauterize in order to stop bleeding, he is actually causing more bleeding. He must therefore make repeated attempts to cauterize the area, first cauterizing, then tearing away tissue, then recauterizing the torn tissue, etc. Once again, in an attempt to alleviate the problem, surgeons will typically operate at low power, resulting in a procedure requiring much more time to complete than is desirable.
Another problem caused by heated electrodes is the creation of steam and smoke in the proximity of the surgical site. As a result, the surgeon's visibility is reduced, and he must periodically interrupt the procedure to allow the steam or smoke to dissipate.
It has been recognized that cooling the surgical site during electrosurgery would be desirable. In response, systems have been developed which flush the surgical site with fluid during surgery. However, this results in much more steam being created at the surgical site and the associated reduction in visibility. Also, the fluid introduced at the site must be aspirated as the procedure is performed.
SUMMARY OF THE INVENTION
The present invention is directed to an electrosurgical device and system and a method of electrosurgery in which electrosurgical electrodes are cooled. The device of the invention includes at least one electrode for applying the required electrical energy to tissue at a surgical site. During surgery, an internal cavity within the electrode contains a cooling medium such as water. The cooling medium is contained within the electrode at the surgical site such that it does not flow into the site.
The present invention is applicable to monopolar electrosurgery in which the device includes a single electrode and bipolar electrosurgery in which the device includes two electrodes, each of which contains the cooling medium. The invention is also applicable to any of the various electrosurgical procedures, including electrocautery, cutting and coagulation. In one embodiment, the electrosurgical device is an endoscopic device and can be inserted into a patient through a cannula. In another embodiment, the device is used in open surgical procedures.
In a preferred embodiment, the cooling medium is circulated through the cavity within the electrode. In that embodiment, the cavity is open at the proximal end of the device. The cooling medium enters the device through an inlet port, flows within the cavity to the distal end of the device and returns back to the proximal end of the device where it exits the device through an outlet port. In a preferred embodiment, the cooling medium such as water is provided from a fluid source bag or bottle suspended at some height above the device. The fluid flows by gravity out of the source bag through tubing to the inlet port of the electrosurgical device. The fluid exiting the device at the outlet port flows through outlet tubing to a collection bag or bottle. Hence, the electrode is cooled by a closed circulation system including the two bags, the tubing and the cavity or lumen within the electrode.
In another embodiment, the cooling fluid is pumped through the electrode by a circulation pump. In one embodiment, a source bag and collection bag are used as in the gravity-feed embodiment. However, a peristaltic roller pump is added to periodically squeeze a flexible fluid inlet tube to pump the cooling fluid through the electrosurgical device to the collection bag. Alternatively, a circulation pump can pump the fluid from a fluid reservoir into the device. The fluid circulates through the device and returns to the reservoir. The reservoir may be cooled such as by fins and/or blowers to remove heat from the system.
In another embodiment, instead of circulating the cooling medium through the electrodes, each electrode is configured as a heat pipe heat transfer device. That is, the electrode is closed at both its proximal and distal ends. The cavity within each electrode is evacuated and contains a liquid cooling medium such as water. When the distal end of an electrode contacts tissue heated by the electrosurgical procedure, the cooling medium inside the electrode evaporates, filling the internal cavity with vapor. At the proximal end of the electrode, the vapor condenses, and the resulting liquid flows back toward the distal end of the device via a wick. Heat is thus carried away from the distal end to cool the electrode at the surgical site. At the proximal end of the electrode, a heat exchanger in the form of extern
Levine Andy H.
Lichtman Philip R.
Meade John C.
Cohen Lee
Hamilton Brook Smith & Reynolds P.C.
Seedling Enterprises, LLC
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