Valleylab, Inc.

Sherwood Services Ag

Michael S Klicek

Robert B Stoddard

Louis Delahuerga

Daniel J Becker

Alan Broadwin

Michael Dickson Olichney

William G Paterson

Emery S Rose

David A Zieve

William G Patterson

Alexander S Kreizman

A constant power control circuit for an electrosurgical generator and a method for maintaining the electrical power output of an electrosurgical generator at a generally constant value throughout a given tissue impedance range are disclosed. The constant power control circuit and the method recognize and use the unique and simple linear characteristics associated with certain electrosurgical generator designs to monitor and control the electrical power output without having to calculate or monitor the actual output power. The constant power control circuit includes a current sampling circuit, a linear conversion circuit, and a feedback correction circuit. The constant power control circuit may also include protection circuitry that prevents the electrosurgical generator from being over-driven during high and/or low impedance loading, and reduces the severity of exit sparking by providing a quick response to high impedance indications while nonetheless maintaining increased power levels throughout a preset, nominal impedance range. The constant power control circuit and method may be included as an integral part of the overall electrosurgical generator's circuitry, or may be embodied as a separate unit that connects to, and controls, an electrosurgical generator. The constant power control circuit and method may be embodied through a variety of analog and/or digital circuit components or arrangements, including software running on computational and memory circuitry.

Electrosurgical generator power control circuit and method

An electrosurgical generator control responds to tissue impedance between active and return electrodes during desiccation. Active and return generator leads to supply energy and a user control sets the level of energy desired for electrosurgery. Voltage and current sensing circuits respond to high frequency energy in the leads to signal voltage and current in the leads. A multiplier receives the signals to calculate power. A clock sets units of time during for which power calculation. An integrator calculates the energy supplied through the leads per time unit. The user control sets a reference signal for the energy level desired. A correlation circuit receives the energy calculations from the integrator and the reference signal and provides a feedback signal to indicate when the energy calculation equals the user control setting for altering the generator supply of energy to the leads. A counter assesses the number of packets of energy delivered against a setting of the user control and the total energy delivered is a function of multiple packet sequences containing pulses wherein the time between the pulses is controlled by the user control. The method uses the automatic control in measuring impedance during tissue desiccation and altering the output of an electrosurgical generator.

Automatic control for energy from an electrosurgical generator

A control responds to impedance and temperature between active and return electrodes of the electrosurgical generator during tissue desiccation. Tissue contacts separately and independently provide high frequency power to effect tissue electrosurgically. An instantaneous impedance monitor between each contact and the return electrode signals. A regulator receives the signals and separately and independently controls tissue impedance at each contact in accord with signals to change independently the power to the return electrode. A temperature sensor for each contact transmits its temperature to the generator to regulate power to each contact. A first multiplexer provides high frequency electrosurgical power separately and independently to each contact from the generator. A second multiplexer relays temperature amounts of each contact to the generator. A method of control responds to tissue impedance by supplying high frequency power separately and independently to contacts, monitoring, regulating and controlling impedance between the contacts and the return electrode to set the generator power applied by each contact. Transmitting temperature amounts for each contact with sensors regulates contact power.

Impedance and temperature generator control

An active electrode switches from a monopolar mode extending from a handpiece and a patient return to a bipolar mode with the active and return electrodes extending. An active lead selectively connects the active output and the active electrode. A return lead selectively connects the return electrode and the return output in the monopolar mode or the return terminal when in the bipolar mode. Terminals connect with wiring to the electrodes to complete the circuit for the bipolar mode. One terminal is on the generator and one is in the handpiece to connect to the electrodes and complete the circuit for bipolar. The electrode has a control on the handpiece for the surgeon to change circuitry and to position the electrode for each mode. The return electrode in the monopolar mode is in the handpiece disconnected from its terminal. The return electrode connects to its terminal when extended from the handpiece but for monopolar a pair of patient pads connected to a monitoring circuit test continuity. A method of use has steps of switching the electrode from the monopolar to bipolar, providing the generator with outputs to the electrodes, having terminals for the electrodes when used for bipolar, including an active lead selectively in circuit between the active output and electrode and including a return lead selectively in circuit between the return electrode and output when monopolar or the terminal when bipolar.

Moveable switchable electrosurgical handpiece

An electrosurgical control for a trocar has a trocar with a cannula with a stylet coaxially fit therein. The stylet is movable relative to the cannula along a common axis. The trocar is shaped for insertion in a direction generally along the axis through tissue in a puncture procedure with its stylet. A distal end and a proximal end on the elongate cannula so the distal end enters the tissue while the proximal end remains outside. A tip on the stylet end, near the distal end of the cannula, normally extends therebeyond in position to puncture the tissue. The stylet has an energy supply passing from the tip to its opposite end and moves reciprocally relative to the cannula so the tip extends or is fully within the cannula. An electrosurgical generator provides energy to the opposite end of the stylet and an electrosurgically active device is a part of the tip and connects to the energy supply. A sampling circuit connected to the electrosurgically active device and responds to changes in energy passing through the energy supply as a function of tissue cut by the electrosurgically active device. The sampling circuit provides a signal relative to the energy supplied and a measuring circuit analyzes the signal to instantly isolate a specific signal therefrom indicative of a significant change in the energy when the tip is not in tissue. A comparator has a settable predetermined threshold amount of energy at which the electrosurgical generator no longer supplies energy. A peak energy level is set by a knob and is compared to the varying signals from the sampling circuit. A switch responds to the comparator to disconnect the energy when the threshold is exceeded.

Electrosurgical control for a trocar

An ultrasonic oscillator drives a tool at a set frequency. An amplitude control runs the oscillator to set the vibration level. A frequency regulator joins the amplitude and the oscillator. A control feedback loop, in the frequency regulator, keeps handpiece linear dynamics. An operational transconductance amplifier, in the oscillator, governs gain of the loop. A circuit connects to the control to retard the rate of current application over time to the amplifier. The circuit has switching to either retard the rate or reset for start up. The amplifier is a current output device with current directly proportional to the bias current and input voltage with bias as gain change for the loop. The circuit limits the bias to the amplifier to modify frequency response and output current. A capacitor delays application of the bias to the amplifier. Replaceable tools of various lengths or shapes positioned along an axis vibrate for surgery at the frequency and a wave length. Tools longer than one wavelength and of configurations tuned to oscillate around the frequency resonate as a function of their material, length and configuration. A flue surrounds the tool and has a hollow elongate semi rigid central body about an axis with a funnel, at one end thereof and a nozzle, at the other to direct annular irrigant/coolant flow therethrough. The funnel and nozzle are resilient. Reinforcing ridges, inside the nozzle, act to maintain concentricity between the flue and nozzle tip and channel irrigant thereabout.

Ultrasonic surgical handpiece and an energy initiator

Apparatus and method find leakage due to tissue load or transients and has active and return electrodes for RF energy sensed by transformers for a circuit that finds leakage at more than two thousand times per second or a frequency dependent on the phase shift between voltage and current. Software and feedback manage V.sub.rms to reduce the voltage or increase the crest factor, which is V.sub.rms divided by peak voltage, by pulse width modulation of the RF drive. Voltage and current phase shift changes, angle .theta., are compared to a threshold, and when greater, the frequency at which the differences between the active and return current signals are examined is increased. The differences between the active and return currents are examined and when greater than maximum leakage while in coagulation mode, the RF drive pulse width is reduced to maintain voltage wave peaks at a preset value and reduce V.sub.rms thereby reducing leakage to the allowable maximum. Reducing the duty cycle or the pulse width of the output wave increases the crest factor. When the differences between active and return currents are greater than a maximum for leakage while in cut or bipolar mode, the V.sub.rms is reduced to limit leakage to a maximum level. When the phase angle .theta. is less than a threshold, the frequency with which leakage is examined is reduced.

Apparatus for leakage control and method for its use

A circuit, for monitoring and controlling parameters of an electrosurgical unit, ESU, relative to load and the RF energy, has a load responsive output sensing circuit that measures the ESU load. A signal modifier, attached to the sensing circuit enhances the signals measured and transmits them to a buffer. An analog to digital converter, A/D, digitize the signals and samples wave pulse train at about eight million samples per second. A data memory stores the digitized signals. A RF drive clock connects to the ESU output; a sample clock uses phase shifting to interrogate the input signals to a processor, DSP, at a greater sampling rate of frequency than without. The DSP receives the stored signals from the data memory and processes them while monitoring and calculating ESU parameters measured, i.e. voltage, current, power, load impedance, leakage current, peak to peak voltage, peak to peak current, spectral content and/or crest factor of the RF wave pulse train energy to use as controlling feedback to the either a high voltage power supply in the ESU, regulating the RF drive pulses or both. A method monitors and controls the ESU relative to load has the steps of collecting parameters with the ESU output sensing circuit responsive to loads; enhancing signals with the signal modifier; transmitting signals to the buffer; converting signals with the A/D converter; storing signals in the data memory; receiving signals in the DSP, and processing, monitoring and controlling signals by repeatedly measuring ESU output parameters.

Electrosurgical processor and method of use

An electrosurgical bipolar treating apparatus comprising a handpiece to which is connected a first active electrode and a second return electrode having exposed distal ends which define a bipolar tip for electrosurgically treating tissue at an operational site on a patient, which tip is structured so that both distal ends simultaneously contact said tissue and wherein the active electrode has a higher tissue to electrode impedance than the return electrode.

Electrosurgical bipolar treating apparatus

Electrosurgical apparatus for performing at least cutting and coagulation of biological tissue, which comprises a hand operated electrosurgical pencil comprising an electrically insulated housing and an electrode with a distal end defining a tip, means for supplying high-frequency, alternating current, electrical energy from a generator through the electrode to the tissue and means for returning electrical energy from the tissue to the generator to complete an electrical circuit, switching means mounted on the housing for selecting the cut mode or the coagulating mode, which switching means is connected to an isolated low voltage, direct current circuit which provides an appropriate signal to control the generator in the cut mode or coagulating mode, respectively, whereby the generator supplies the desired high-frequency, alternating current, electrical energy to the electrode and current leakage is limited.

Electrosurgical apparatus

An electrosurgical tubular trocar system has a hollow tube substantially longer than its diameter. The tube is shaped for insertion in a direction generally along its axis through tissue of a human or animal body. Distal and proximal ends on the tube enter and remain outside the tissue, respectively. A tip on the distal end punctures tissue of a human or animal. An insulating portion of high dielectric material extends along the tube between the distal and proximal ends. An electrode on the insulating portion extends from the proximal end to the tip to transmit radio frequency energy. An energy supply at the electrode proximal end permits the passage of energy to the tip. An electrosurgical generator as part of the energy supply has a control to regulate the amplitude and frequency of the energy. A return path in circuit with the tip and the energy supply cuts and/or coagulates. A tip point at an acute angle to the axis lessens the initial force necessary for entry of the tube. The return path is a conductor on the insulating portion for bipolar cutting across a gap. A passage is made through the tissue. The tube may be conductive. The insulating portion may extend along the tube and be tubular. The electrode may be part of the tube when the conductor is on the insulating portion or the conductor may be part of the tube and the electrode may be on the insulating portion. The tube may be tapered from a smaller diameter at the tip and be smooth. The tip is chamfer and circular. An alternate system may have the return path as a conductive pad in contact with the tissue as a monopolar circuit. The tube may be in fluid communication for flow. A method of placing a trocar aligns an axis normal to the skin, energizes a generator, cuts electrosurgically tissue, drives the tube through the tissue, and disconnects the generator.

Electrosurgical tubular trocar

A device for enhancing the safety and efficiency of a hand-operated electrosurgical pencil having an exposed electrode with a distal end defining a tip for cutting biological tissue, which device comprises a nose piece adapted to be mounted about said electrode and defining at least one pathway for a stream of gas which shrouds the electrode at or near the tip thereof, and electrosurgical apparatus incorporating the device and a method for cutting biological tissue using the apparatus.

Enhanced electrosurgical apparatus

An electrical circuit system which provides electrical energy to a surgical apparatus having ultrasonic fragmentation, aspiration and electrosurgical coagulation capabilities, which system also includes an impedance sensing network and automatic feedback power output control to reduce RF power output as load impedance increases, thereby reducing RF leakage current.

Electrosurgical and ultrasonic surgical system

A device for enhancing the safety and efficiency of a hand-operated electrosurgical pencil having an electrode with a distal end defining a tip for cutting or coagulating biological tissue, which device comprises a nose piece adapted to be mounted about said electrode and containing conduit means defining converging pathways for streams of gas which impinge obliquely on said electrode at or near the tip thereof, and electrosurgical apparatus incorporating said device and a method for coagulating or cutting biological tissue using said apparatus.

Growing community of inventors

Boulder, CO, United States of America

Michael S Klicek