Abstract: An electrosurgical instrument, for the treatment of tissue in the presence of an electrically-conductive fluid medium, comprises an instrument shaft, and an electrode assembly at one end of the shaft. The electrode assembly comprises a tissue treatment electrode and a return electrode which is electrically insulated from the tissue treatment electrode by means of an insulation member. The tissue treatment electrode has an exposed end extending laterally through a cut-out provided in the insulation member at the distal end portion of the instrument. The return electrode has a fluid contact surface which overlies the insulation member in the region of the cut-out. The fluid contact surface is spaced from the tissue treatment electrode in such a manner as to define, in use, a conductive fluid path that completes an electrical circuit between the tissue treatment electrode and the return electrode.

Abstract: An electrosurgical cutting device comprises an instrument body, and first and second cutting blades, at least one of which is pivotally mounted on the body to execute a scissor action with respect to the other blade. Electrical supply conductors associated with the body supply an electrosurgical voltage to the first and second blades. The first blade is a composite blade comprising a conductive outer electrode, an inner conductive layer, sandwiched between the outer electrode and the inner layer, an insulating layer. The supply conductors are connected respectively to the outer electrode and to the inner layer.

Abstract: In electrosurgical apparatus for tissue desiccation and cutting, an electrosurgical generator has a series-connected output inductor which forms a series resonant circuit with the capacitance of the generator load, the load including an electrode unit and a cable coupled to the generator output. The series resonant frequency is typically 1.5 f where f is the operating frequency of the generator. A capacitor may be included, coupled between the conductors which connect bipolar electrodes to the generator, to increase the load capacitance. The effect of these measures is to boost the output voltage available for electrosurgical treatment, especially for tissue cutting.