Patent ID: 7220260

Claim:
A method of cutting tissue at a target site, comprising: i) providing a bipolar cutting blade comprising first and second electrodes and an electrical insulator spacing apart the electrodes, ii) bringing the blade into position with respect to the target site such that one electrode is in contact with tissue at the target site and the other is adjacent thereto, iii) supplying an electrosurgical voltage to the cutting blade such that arcing does not occur in air between the first and second electrodes but that arcing does occur between one of the electrodes and the tissue at the target site, the voltage supplied, capable of vaporising tissue, iv) repeatedly measuring the impedance between the first and second electrodes, v) calculating the difference between successive impedance measurements, vi) summing the calculated difference values for a predetermined number of impedance difference calculations to obtain a total value, and vii) interrupting the electrosurgical voltage when the total value exceeds a predetermined threshold value.