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Method and apparatus for electrosurgically treating tissue

  • US 5,540,684 A
  • Filed: 07/28/1994
  • Issued: 07/30/1996
  • Est. Priority Date: 07/28/1994
  • Status: Expired due to Term
First Claim
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1. An electrosurgical apparatus for coagulating tissue during a surgical procedure, said apparatus comprising:

  • first and second elements electrically insulated from one another and movable relative to one another for engaging tissue to be coagulated therebetween;

    a power controller responsive to a power control signal for controlling RF energy connected to said first and second elements;

    impedance measurement circuitry coupled to said first and second elements for measuring the impedance of tissue between said first and second elements, said impedance measuring circuitry including;

    a first device for storing an initial maximum impedance value; and

    a second device for storing a minimum impedance value;

    a threshold determining circuit coupled to said first and second devices for determining a threshold impedance value between said initial maximum impedance value and said minimum impedance value; and

    a first comparator operatively associated with said threshold determining circuit for comparing measured impedance values to said threshold impedance value and generating a power control signal to stop said power controller upon said measured impedance value exceeding said threshold impedance value.

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