Impedance feedback monitor for electrosurgical instrument
First Claim
1. An electrosurgical device for treating tissue during a surgical procedure, said device comprising:
- a surgical instrument having a tissue treating portion including an end effector adapted to engage tissue to be treated;
electrically isolated first and second poles comprised of tissue contacting first and second electrodes adapted to receive electrosurgical energy from an energy source connected to said electrodes, said first and second electrodes being capable of conducting electrical energy therebetween, at least one of said first and second electrodes being connected to said tissue treating portion of said instrument;
an energy control signal generated by an energy control signal generator for controlling RF energy supplied from said energy source to said electrodes;
impedance measurement circuitry coupled to said electrodes for measuring the impedance of tissue engaged by said end effector, wherein said impedance measuring circuitry is adapted to determine a minimum impedance value, to determine a target impedance value as a function of said minimum impedance value and to compare measured impedance values to said target impedance value and alter said control signal when said measured impedance value exceeds said target impedance value.
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Accused Products
Abstract
An impedance monitoring device is provided for monitoring the electrical impedance of tissue as it is treated with electrosurgical energy. Based on a predicted model of tissue impedance and a number of initial impedance readings, the impedance at which tissue treatment is completed is predicted. More particularly, a minimum impedance level is measured and a function of the minimum impedance is used to determine impedance at which coagulation is completed. A control device is provided for bringing the output of the generator within an optimum range based on a system load curve. In one embodiment the impedance monitoring device is used in conjunction with a bipolar electrosurgical instrument. Preferably, the instrument comprises electrically opposite electrodes located on one or more tissue engaging surfaces for engaging tissue to be treated.
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Citations
11 Claims
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1. An electrosurgical device for treating tissue during a surgical procedure, said device comprising:
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a surgical instrument having a tissue treating portion including an end effector adapted to engage tissue to be treated; electrically isolated first and second poles comprised of tissue contacting first and second electrodes adapted to receive electrosurgical energy from an energy source connected to said electrodes, said first and second electrodes being capable of conducting electrical energy therebetween, at least one of said first and second electrodes being connected to said tissue treating portion of said instrument; an energy control signal generated by an energy control signal generator for controlling RF energy supplied from said energy source to said electrodes; impedance measurement circuitry coupled to said electrodes for measuring the impedance of tissue engaged by said end effector, wherein said impedance measuring circuitry is adapted to determine a minimum impedance value, to determine a target impedance value as a function of said minimum impedance value and to compare measured impedance values to said target impedance value and alter said control signal when said measured impedance value exceeds said target impedance value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of operating a device for electrosurgically treating tissue during a surgical procedure, said method comprising the steps of:
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applying RF energy to tissue to be electrosurgically treated by means of an electrosurgical instrument; measuring the impedance of the tissue treated by said electrosurgical instrument; generating an impedance signal representative of the measured impedance value of said tissue; determining a representative minimum impedance value; determining a representative target impedance value as a function of said minimum impedance value; comparing measured impedance values to said target impedance value; and generating a control signal to control the RF energy to said electrosurgical instrument in response to said measured impedance value exceeding said target impedance value. - View Dependent Claims (10)
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11. An electrosurgical impedance feedback control device, said device comprising:
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impedance measurement circuitry adapted to be coupled to tissue contacting electrodes connected to a tissue treating portion of a surgical instrument and to an energy source arranged to supply therapeutic electrosurgical energy to said electrodes, wherein said impedance measurement circuitry is adapted to measure the impedance of tissue engaged by the tissue treating portion of the surgical instrument; said impedance measuring circuitry comprising; a first device for determining a minimum impedance value; a target determining device coupled to said first device, for determining the target impedance value as a function of said minimum impedance value; and a first comparison device for comparing measured impedance values to said target impedance value and generating a signal indicating whether said measured impedance value exceeds said target impedance value.
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Specification