Abstract: Surgical apparatus for bipolar diathermy has a radio frequency generator connectible to a cutting assembly which includes a support structure having a pair of electrical supply conductors and, mounted at the distal end of the support assembly, a tissue cutting head. The cutting head comprises a loop of material which is electrically conducting and has a negative temperature coefficient (NTC) of resistance, such as silicon carbide. In operation, radio frequency power from the generator causes heating of the loop to a temperature at which its resistivity rises to level which exceeds that of living tissue with the result that diathermy currents pass through the tissue. Also disclosed is a pair of forceps with electrodes made of NTC material, for cauterization.

Abstract: Electrosurgical cauterizing apparatus has a radio frequency generator with a power oscillator which generates a bipolar cauterizing output signal for application to a pair of cauterizing electrodes. The oscillator carrier frequency varies according to the load resistance represented by tissue being cauterized and this variation is used to monitor the tissue resistance as cauterization progresses. The apparatus generates a cauterisation termination signal according to progress of the tissue resistance on a resistance versus time curve characteristic of the tissue cauterization process.