Electrosurgical generator and system
AssigneeGyrus Medical Limited
InventorsNigel Mark Goble, Colin Charles Owen Goble
Life of this patent
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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 vaporisation or cutting mode to limit the size of the steam pocket at the electrodes and to avoid electrode burning.
Claims25
An electrosurgical generator for supplying radio frequency power to an electrical instrument, the generator comprising:
- a radio frequency output stage having at least a pair of electrosurgical output connections for the delivery of radio frequency power to the instrument, said output stage further comprising a resonant output circuit coupled to the output connections and a switching device coupled to the resonant output circuit;
- a power supply coupled to the output stage for supplying power to the output stage;
- and
- control circuitry including a sensing circuit for deriving a sensing signal representative of the radio frequency peak output voltage developed across the output connections, said control circuitry operable to actuate the switching device to reduce the delivered radio frequency power when the peak output voltage reaches a predetermined threshold limit.
An electrosurgical generator for supplying radio frequency power to an electrosurgical instrument, the generator comprising:
- a radio frequency output stage having at least a pair of electrosurgical output connections for delivery of radio frequency power to the instrument, said output stage further comprising an output circuit coupled to the output connections and a switching device coupled to the resonant output circuit;
- a power supply coupled to the output stage for supplying power to the output stage;
- and
- control circuitry including sensing means for deriving a sensing signal representative of the radio frequency peak output voltage developed across the output connections, said control circuitry operable to actuate the switching device to reduce the delivered radio frequency power,
- wherein the switching device is connected between the resonant output circuit and one of a pair of supply rails of the power supply means, and connected so as to switch current repeatedly through the resonant output circuit at its resonant frequency, and wherein the control circuitry is so arranged and coupled to the switching device as to reduce the “on” time of the switching device during individual radio frequency switching cycles sufficiently rapidly to cause a 50% reduction in delivered output power within 100 μs of the predetermined threshold having been reached.
An electrosurgical generator for supplying power to an electrosurgical instrument, the generator comprising:
- a radio frequency output stage including a radio frequency oscillator and a radio frequency power device coupled to the oscillator and having at least a pair of electrosurgical output connections for delivery of radio frequency power to the instrument,
- a power supply which is coupled to the output stage and supplies power thereto,
- control circuitry including sensing means for deriving a sensing signal representative of peak voltage across the output connections, the control circuitry having a first output coupled to the power device to reduce the radio frequency duty cycle thereof and a second output coupled to the power supply to effect a reduction in the average power supply voltage supplied to the output stage, said reductions occurring in response to the sensing signal reaching a predetermined threshold to thereby reduce the radio frequency power delivered to the instrument.
An electrosurgical generator for supplying radio frequency power to an electrosurgical instrument, the generator comprising:
- a radio frequency output stage having at least a pair of electrosurgical output connections for the delivery of radio frequency power to the instrument,
- means coupled to the output stage for supplying power to the output stage, and
- control circuitry including sensing means for deriving a sensing signal representative of the peak radio frequency output voltage developed across the output connections and means responsive to the sensing signal for causing a reduction in delivered output power independently of supply voltage or in addition to supply voltage reduction when the sensing signal is indicative of a predetermined threshold having been reached by said peak radio frequency output voltage.
An electrosurgical generator for supplying power to an electrosurgical instrument, the generator comprising:
- a radio frequency output stage having at least a pair of electrosurgical output connections for delivery of radio frequency power to the instrument,
- means coupled to the output stage for supplying power to the output stage;
- and
- control circuitry including sensing means for deriving a sensing signal representative of the radio frequency peak output voltage developed across the output connections, and means responsive to the sensing signal for causing a reduction in delivered output power independently of supply voltage or in addition to supply voltage reduction when the sensing signal is indicative of a predetermined threshold having been reached,
- wherein the means for causing a reduction in delivered output power is operable to cause at least a 50% reduction in delivered output power when the sensing signal is indicative of said threshold having been reached, said reduction being effected within a period of 20 μs or less, and
- wherein the means for causing a reduction in output power include a first control line coupled to the radio frequency output stage for feeding a first power reduction control signal to said output stage.
Dependencies are inferred from the claim text.