Control system for neurosurgery

A method for controlling a system for neurosurgical bipolar electrodes for application to tissue and bodily fluids of a patient, the tissue and bodily fluids having a tissue impedance, the method comprising the steps of:

• providing a source of high frequency energy having an output stage and an operating frequency;
• connecting bipolar electrodes to the source of high frequency energy, the bipolar electrodes having contact surfaces of highly electrically conductive material having resistance per unit area substantially less than the tissue impedance;
• contacting the tissue and bodily fluids with the contact surfaces;
• connecting a tank network to the output stage of the source of high frequency energy, the tank network including at least a tank capacitor and at least a tank inductor, the at least tank capacitor and the at least tank inductor tuned to the operating frequency;
• inductively coupling a first current transducer to the bipolar electrodes:
• responding with the first current transducer to the tissue impedance at the particular instant of treatment of the tissue and bodily fluids;
• providing with the first current transducer a measure relative to the instantaneous values of current through the tissue and bodily fluids;
• inductively coupling a second current transducer to the source of high frequency energy to respond to current through a second capacitor applied across the contact surfaces;
• generating a signal with the second current transducer, the signal generated in response to the tissue impedance;
• the signal correlated to an instantaneous value of voltage between the contact surfaces;
• connecting a control to the source of high frequency energy for initially regulating current applied through the tissue and bodily fluids by the contact surfaces;
• responding with the control to the tissue impedance until the signal divided by the measure reaches a predetermined value;
• connecting the control for then regulating power applied to the tissue and bodily fluids by the contact surfaces in accord with the tissue impedance until the signal divided by the measure reaches a predefined value;
• responding thereafter with the control to the signal divided by the measure so that voltage between the contact surfaces is regulated while monitored until the signal divided by the measure is a prescribed value, so that the tissue and bodily fluids being treated are moist but coagulated at the surface and not completely dry and carbonized.

A control system for neurosurgical bipolar electrodes for application by a surgeon to tissue and bodily fluids of a patient, the tissue and bodily fluids having a tissue impedance, the control system comprising:

• a source of high frequency energy having an output and an operating frequency;
• a tank network in the source of high frequency energy, the tank network having at least a tank capacitor and at least a tank inductor, the at least tank capacitor and the at least tank inductor tuned to the operating frequency of the source of high frequency energy, the tank network as the output of the source of high frequency energy for generating an output power and an output voltage;
• bipolar electrodes connected to the output of the source of high frequency energy;
• contact surfaces on the bipolar electrodes, the contact surfaces comprised of highly electrically conductive material with resistance per unit area substantially less than the tissue impedance;
• a first current transducer inductively coupled to the bipolar electrodes the first current transducer responsive to the tissue impedance, the first current transducer providing a measure relative to a first current through the tissue and bodily fluids;
• a second current transducer attached to the source of high frequency energy to respond to a second current through a second capacitor applied across the contact surfaces, the second current transducer providing a signal of changes in the second current, the signal representative of the output voltage;
• a control connected to the source of high frequency energy for regulating the first current, the output power and the output voltage and for responding to the tissue impedance, the control connected for receiving the measure and the signal in real time;
• a microprocessor in the control, the microprocessor for receiving from the control and thereafter relating the measure to the signal, the microprocessor having memory for a predetermined value and for assessing when the signal divided by the measure equals the predetermined value, the microprocessor having memory for predefined value and for assessing when the signal divided by the measure equals the predefined value, the microprocessor having memory for a prescribed value and for assessing when the signal divided by the measure equals the prescribed value, and
• the control connected to the source of high frequency energy for regulating the first current applied to the tissue and bodily fluids by the contact surfaces in accord with the tissue impedance until the signal divided by the measure is the predetermined value, the control for thereafter responding to the signal divided by the measure so that the output power is regulated while monitored until the signal divided by the measure is the value, the control connected for finally regulating the output voltage by changing the output voltage to a percentage of that applied to the tissue and bodily fluid until the prescribed value is obtained so that the tissue and bodily fluids being treated are moist but coagulated at the surface and not completely dry and carbonized.