Electrosurgical generator method
First Claim
1. A method of operating an electrosurgical system which has a generator with an output coupled to an electrode assembly having an electrode for operation in a conductive liquid, wherein the method comprises:
- applying radio frequency power to the electrode, and automatically adjusting the radio frequency power applied to the electrode to maintain the conductive liquid adjacent the electrode at its boiling point for tissue desiccation, so that vapour bubbles form on the electrode'"'"'s surface without forming a vapor pocket surrounding the electrode.
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Abstract
An electrosurgical system including an electrode assembly having two electrodes for use immersed in an electrically conductive fluid has a generator with control circuitry for rapidly reducing the delivered radio frequency output power by at least 50% within at most a few cycles of the peak radio frequency output voltage reaching a predetermined threshold limit. In this way, tissue coagulation can be performed in, for example, saline without significant steam generation. The same peak voltage limitation technique is used in a tissue vaporization or cutting mode to limit the size of the steam pocket at the electrodes and to avoid electrode burning.
2035 Citations
17 Claims
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1. A method of operating an electrosurgical system which has a generator with an output coupled to an electrode assembly having an electrode for operation in a conductive liquid, wherein the method comprises:
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applying radio frequency power to the electrode, and automatically adjusting the radio frequency power applied to the electrode to maintain the conductive liquid adjacent the electrode at its boiling point for tissue desiccation, so that vapour bubbles form on the electrode'"'"'s surface without forming a vapor pocket surrounding the electrode. - View Dependent Claims (2, 3, 4, 5)
selecting one of the said modes;
when the desiccation mode is selected, automatically adjusting the radio frequency power supplied to the electrode assembly to maintain the conductive liquid adjacent the electrode at its boiling point for tissue desiccation without creating a vapour pocket surrounding the electrode; and
when the cutting or vaporization mode is selected, automatically adjusting the radio frequency power supplied to the electrode to maintain a vapor pocket surrounding the electrode.
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3. A method according to claim 2, wherein, in the cutting or vaporisation mode, the radio frequency power supplied to the electrode is automatically limited to prevent overheating of the electrode.
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4. A method according to claim 3, wherein the radio frequency power supplied to the electrode is automatically adjusted by limiting the output voltage applied to the electrode to predetermined first and second voltage values, the first voltage value being used in the desiccation mode, and the second voltage value, which is higher than the first voltage value, being used in the cutting or vaporisation mode.
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5. A method according to claim 4, wherein the first and second voltage values are in the ranges of from 150V to 200V and from 250V to 600V respectively, the voltages being peak voltages.
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6. A method of operating an electrosurgical system which has a generator with an output coupled to an electrode assembly having an electrode for operation in a conductive liquid, wherein the method comprises:
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applying radio frequency power to the electrode, monitoring an electrical signal related to the voltage developed at the output of the generator, and reducing the applied power when said signal reaches a predetermined threshold value associated with an increased load impedance, whereby only sufficient radio frequency power is applied to the electrode to maintain the conductive liquid adjacent the electrode at its boiling point for tissue desiccation, so that vapour bubbles are formed on the electrode'"'"'s surface without forming a vapour pocket surrounding the electrode. - View Dependent Claims (7, 8, 9, 10, 11)
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12. An electrosurgical tissue desiccation method comprising:
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providing an electrosurgical system comprising an electrosurgical radio frequency generator coupled to an electrode assembly having a treatment electrode;
introducing the electrode assembly into a selected operation site with the treatment electrode contacting the tissue to be treated and with the tissue and the treatment electrode immersed in a conductive liquid;
actuating the generator to apply radio frequency power to the treatment electrode; and
automatically adjusting the radio frequency power during its application to the treatment electrode by the generator to maintain the conductive liquid adjacent the treatment electrode at its boiling point, so that vapour bubbles are formed on the electrode'"'"' surface without creating a vapour pocket surrounding the electrode. - View Dependent Claims (13, 14)
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15. An electrosurgical tissue desiccation method comprising:
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providing an electrosurgical system comprising an electrosurgical radio frequency generator coupled to an electrode assembly having an active electrode and a return electrode, introducing the electrode assembly into a selected operation site with the tissue and said electrodes immersed in a conductive liquid;
actuating the generator to apply electrosurgical power to the active electrode and thereby to locally apply heat to the tissue; and
while the generator is actuated, automatically adjusting the radio frequency power applied to the active electrode by the generator to maintain the conductive liquid adjacent the active electrode at its boiling point so that vapour bubbles are formed on the electrode'"'"'s surface without forming a vapour pocket surrounding the active electrode. - View Dependent Claims (16, 17)
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Specification