Electrosurgical generator
First Claim
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1. An electrosurgical generator comprising a source of electrosurgical energy;
- means adapted for connecting said source to a patient;
means for measuring the impedance of the patient; and
control means responsive to said patient impedance measuring means for decreasing the output power from said source with increasing patient impedance, the rate of power decrease being substantially greater than that which would result if the output voltage from the source were maintained constant over the range of increasing patient impedance and substantially less than that which would result if the source of electrosurgical energy were disabled.
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Abstract
An electrosurgical generator having a source of electrosurgical energy connected to a patient and including control circuitry for decreasing the output power from the source with increasing patient impedance, the rate of power decrease being substantially greater than that which would result if the output voltage from the source were maintained constant over the range of increasing patient impedance. The control circuitry may, in particular, decrease the output power over the range of increasing patient impedance in accordance with the square of the impedance.
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Citations
21 Claims
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1. An electrosurgical generator comprising a source of electrosurgical energy;
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means adapted for connecting said source to a patient; means for measuring the impedance of the patient; and control means responsive to said patient impedance measuring means for decreasing the output power from said source with increasing patient impedance, the rate of power decrease being substantially greater than that which would result if the output voltage from the source were maintained constant over the range of increasing patient impedance and substantially less than that which would result if the source of electrosurgical energy were disabled. - View Dependent Claims (2)
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3. An electrosurgical generator comprising an adjustable source of a electrosurgical energy;
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means adapted for connecting said source to a load including a patient; and control means for adjusting the actual power delivered to said load from said source including; means for determining the impedance of said load; means responsive to all said impedance above a first predetermined value for computing a correction factor depending on the value of said impedance, said correction factor corresponding to a required load power, said correction factor computing means including means for computing the correction factor so that the power delivered to said load is decreased with increasing patient impedance, the rate of power decrease being substantially greater than that which would result if the output voltage from said source were maintained constant over the range of increasing patient impedance and substantially less than that which would result if said source were disabled; and means responsive to said correction factor for adjusting said source of electrosurgical power so that said actual power follows said required power. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An electrosurgical generator comprising an adjustable source of electrosurgical energy;
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means adapted for connecting said source to a load including a patient; and control means for adjusting the power delivered to said load from said source including; means for measuring the impedance of the patient; means responsive to said patient impedance measuring means for selecting first and second modes of operation of said generator when said load impedance exceeds a predetermined value; means for maintaining the voltage across said load substantially constant for all values of load impedance in excess of said predetermined value in response to said first mode being selected; and means for reducing the power delivered to said load in accordance with the inverse of the square of the load impedance for all values of load impedance in excess of said predetermined value in response to said second mode being selected. - View Dependent Claims (18, 19, 20, 21)
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Specification