In an electrosurgical generator for generating radio frequency power, the generator includes a radio frequency output stage having two or more output connections, and a power supply coupled to the output stage for supplying power to the output stage. A controller is operable to cause the generator to supply a blended output signal alternating constantly between a first output signal across the output connections in which the radio frequency output voltage developed across the output connections is limited to at least a first predetermined threshold value for cutting or vaporisation of tissue, and a second output signal across the output connections in which the radio frequency output voltage developed across the output connections is limited to a second threshold value for coagulation. There is also provided adjustment means, operable by a user of the electrosurgical generator, for changing between various preset settings for the blended signal, the preset settings each having a predetermined duty cycle of the blended signal that is limited to the first threshold value for cutting or vaporisation, and a predetermined duty cycle of the blended signal that is limited to the second threshold value for coagulation.

Electrosurgical generator and system

An electrosurgical generator has an output power control system that causes the impedance of tissue to rise and fall in a cyclic pattern until the tissue is desiccated. The advantage of the power control system is that thermal spread and charring are reduced. In addition, the power control system offers improved performance for electrosurgical vessel sealing and tissue welding. The output power is applied cyclically by a control system with tissue impedance feedback. The impedance of the tissue follows the cyclic pattern of the output power several times, depending on the state of the tissue, until the tissue becomes fully desiccated. High power is applied to cause the tissue to reach a high impedance, and then the power is reduced to allow the impedance to fall. Thermal energy is allowed to dissipate during the low power cycle. The control system is adaptive to tissue in the sense that output power is modulated in response to the impedance of the tissue.

Electrosurgical generator with adaptive power control

A closed-loop control system is disclosed for use with an electrosurgical generator that generates electrosurgical energy. The closed loop control system includes a user interface for allowing a user to select at least one pre-surgical parameter, such as the type of surgical instrument operatively connected to the generator, the type of tissue and the desired surgical effect. A sensor module is also included for continually sensing at least one of electrical and physical properties proximate a surgical site and generating at least one signal relating thereto. The system also includes a control module for continually receiving the at least one selected pre-surgical parameter from the user interface and each of the signals from the sensor module, and processing each of the signals in accordance with the at least one pre-surgical parameter using at least one of a microprocessor, computer algorithm and a mapping. The control module generates at least one corresponding control signal relating to each signal from the sensor module, and relays the control signal to the electrosurgical generator for controlling the same. A method is also disclosed for performing an electrosurgical procedure at a surgical site on a patient. The method includes the steps of: applying at least one electrical pulse to the surgical site; continually sensing electrical and physical properties proximate the surgical site; and varying pulse parameters of individual pulses of the at least one pulse in accordance with the continually-sensed properties.

Method and system for controlling output of RF medical generator

A control circuit of a surgical device is disclosed. The control circuit includes a first circuit portion coupled to at least one switch operable between an open state and a closed state. The first circuit portion communicates with a surgical generator over a conductor pair to receive a control signal to determine a state of the at least one switch.

Surgical generator for ultrasonic and electrosurgical devices

Electrosurgical energy is used in combination with a surgical tool (12) to seal vessels and vascular tissue of a patient (13). One of the important advances of the present system is that is can effectively seal vessels of a patient (13) without leaving any foreign material in the body of the patient (13). The present system is also capable of sealing vessels as large as ten millimeters in diameter. Another advantage of the present system is that the surgeon can visually inspect the integrity of the seal. The invention works with a combination of pressure and controlled application of electrosurgical energy to achieve the desired result. A surgical tool (12) is used to grasp and apply an appropriate amount of closure force to the tissue of the patient (13). The tool is capable of conducting electrosurgical energy to the tissue concurrently with the application of the closure force. A method for sealing vessels and vascular tissue of a patient (13) includes the steps of applying pressure to the vessels and other tissues of the patient (13); applying a first level of electrosurgical power to the vessels and other tissues sufficient to melt proteins in the tissue; applying a second level of electrosurgical power to the vessels and other tissues sufficient to cause desiccation without charring; reducing the electrosurgical power substantially to zero for a length of time sufficient to allow the vessels and other tissues to cool into a new compressed form; and relieving the pressure on the tissue.

Energy delivery system for vessel sealing

A high frequency surgical apparatus for the thermal coagulation of biologic tissues is described, in which for monitoring the fluctuations in amplitude of the high frequency current during each coagulation process a current monitor (25) is provided, which by means of a current-to-voltage coverter generates an electrical voltage proportional to the amplitude fluctuations of the high frequency current, from which voltage, by means of a first detector, a first direct voltage proportional to the amplitude fluctuations is formed and, by means of a second detector acting as a peak value detector, a second direct voltage is formed that rises in proportion to the amplitude of the high frequency current. The first direct voltage (Ua) and the second direct voltage (kUb), which is divided downward by an adjustable factor by means of a voltage divider, are supplied to a voltage comparator, the output signal of which sets a bistable circuit as soon as the first direct voltage (Ua) becomes lower than the downwardly divided second direct voltage (kUb). The output signal of the bistable circuit switches the high frequency current off until the high frequency current is switched back on again by actuation of a manual switch and/or by means of an automatic switch. Instead of or in addition to this current monitor (25), and electric arc monitor (26) for monitoring the generation of anharmonic frequencies of the base frequency of the frequency generator can be connected to the output of the surgical apparatus, the arc monitor including a filter which passes at least one of the anharmonic frequencies, generated by the electric arc, of the base frequency of the high frequency generator. The output signal of the filter is supplied to a voltage comparator, the output signal of which resets a bistable circuit such that its output signal switches off the high frequency current.

High frequency electrosurgical apparatus for thermal coagulation of biologic tissues

A supplementary acoustic warning signal is provided for a high-frequency electrosurgical unit which sounds only after the lapse of an interval set by a first delay circuit shows that one of the high-frequency generators in the unit remains active longer than what, on the average, is normal. A second delay circuit is provided to assure shut-off of the high-frequency generators if at least one of the high-frequency generators remains active without interruption longer by an interval set by a second delay circuit beyond the lapse of an interval of the interval set by the first delay circuit. The supplementary acoustic signal thus sounds before the second delay circuit shuts off the high-frequency generators. The intervals determined by each of the delay circuits are adjustable. The output signal of the second delay circuit which activates the shut-off relays is maintained until a switch is operated to reset the system, so that the malfunction which has led to shut-down will be dealt with before the unit is used again.

Farin Guenter

Papers

High frequency electrosurgical apparatus for thermal coagulation of biologic tissues

High-frequency electrosurgical unit with timed safety shut down interlock

High frequency surgical instrument for thermally coagulating biological tissue