Ablation performance indicator for electrosurgical devices
First Claim
1. A method of determining a mode of an electrosurgical instrument, comprising:
- supplying a first high frequency square waveform voltage input to the instrument;
sensing a measured current waveform generated at an electrode of the instrument;
determining a peak amplitude and a time-averaged amplitude of the measured current waveform;
calculating a peak-to-average ratio based upon the peak and the time-averaged amplitudes; and
determining whether the electrode of the instrument is in an ablative mode or non-ablative mode based upon the calculated peak-to-average ratio, wherein while supplying the first high frequency voltage input, the calculated peak-to-average ratio of the measured current waveform increases significantly when the instrument is in the ablative mode as compared to the non-ablative mode and wherein during the ablative mode a plasma is generated at the electrode.
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Abstract
Ablation performance indicator for electrosurgical devices is described where ablation is typically characterized by the generation of a plasma discharge at the electrode assembly of an electrosurgical probe. When the electrode begins firing, the current waveform assumes a distinct appearance characterized by a spike at the leading edge of each half cycle followed by a lower level for the remaining period of the half cycle. A calculation of the waveform'"'"'s Crest Factor can be used to determine the state at the electrode, e.g., whether the ablative energy is causing a desirable ablative effect on the electrode. This provides real-time measurements of the RMS and peak current amplitudes along with the Crest Factor and may also be used as limits or inputs to control algorithms or as inputs to indicate whether the device is in its ablative or non-ablative state.
537 Citations
16 Claims
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1. A method of determining a mode of an electrosurgical instrument, comprising:
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supplying a first high frequency square waveform voltage input to the instrument; sensing a measured current waveform generated at an electrode of the instrument; determining a peak amplitude and a time-averaged amplitude of the measured current waveform; calculating a peak-to-average ratio based upon the peak and the time-averaged amplitudes; and determining whether the electrode of the instrument is in an ablative mode or non-ablative mode based upon the calculated peak-to-average ratio, wherein while supplying the first high frequency voltage input, the calculated peak-to-average ratio of the measured current waveform increases significantly when the instrument is in the ablative mode as compared to the non-ablative mode and wherein during the ablative mode a plasma is generated at the electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of determining a state of an electrosurgical instrument, comprising:
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supplying a fixed high frequency square waveform voltage input to the instrument; sensing a measured current waveform generated at an electrode assembly of the instrument; determining a peak amplitude and a time-averaged amplitude of the measured current waveform; calculating a peak-to-average ratio based upon the peak and the time-averaged amplitudes; and determining whether the electrode assembly is generating a plasma, based upon the calculated peak-to-average ratio, wherein the initiation of the plasma at the electrode assembly causes the calculated peak-to-average ratio to increase significantly compared to when no plasma is present.
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16. A method of determining a tissue effect mode of an electrosurgical instrument, comprising:
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supplying a high frequency square waveform voltage input to the instrument; sensing a measured current waveform generated at an electrode of the instrument; determining a peak amplitude and a time-averaged amplitude of the measured current waveform; calculating a peak-to-average ratio based upon the peak and the time-averaged amplitude; and wherein during the supplying step, the tissue effect mode at the electrode may transition between an ablative mode and non-ablative mode while continuing to maintain the high frequency square waveform voltage input;
the tissue effect mode detected based upon the calculated peak-to-average ratio wherein the calculated peak-to-average ratio is significantly higher when the instrument is in the ablative mode as compared to the non-ablative mode.
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Specification