Independent Control of Dual RF Bipolar Electrosurgery

Abstract

To provide systems and methods for controlling an electrosurgical generator capable of controlling a plurality of bipolar electrosurgical devices that deliver two separate bipolar radio frequency waveforms.SOLUTION: An electrosurgical generator comprises a first radio frequency source including: a first power supply configured to output a first direct current waveform; a first radio frequency inverter coupled to the first power supply and configured to generate a first interrogation waveform and a first radio frequency waveform from the first direct current waveform; and a first controller configured to control the first radio frequency inverter to output the first radio frequency waveform based on a response of the first interrogation waveform.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of and priority to U.S. Provisional Patent Application Nos. 63 / 028,012, 63 / 028,007, 63 / 028,009, and 63 / 028,049, each of which was filed on May 21, 2020. The entire contents of each of the foregoing applications are incorporated herein by reference. [Background technology]

[0002] FIELD OF THE DISCLOSURE The present disclosure relates to systems and methods for controlling an electrosurgical generator, and in particular to controlling a multi-bipolar electrosurgical device that delivers two separate bipolar radio frequency waveforms. Related Technology Background

[0003] Electrosurgery involves the application of high radio frequency electrical current to a surgical site to cut, ablate, desiccate, or coagulate tissue. In monopolar electrosurgery, a source or active electrode delivers radio frequency alternating current from the electrosurgical generator to the target tissue. A patient return electrode is placed remote from the active electrode to carry the current back to the generator.

[0004] In bipolar electrosurgery, a return electrode and an active electrode are placed in close proximity to one another such that an electrical circuit is formed between the two electrodes (e.g., in the case of electrosurgical forceps). In this manner, the applied current is confined to the body tissue positioned between the electrodes. Thus, bipolar electrosurgery generally involves the use of equipment in which it is desired to achieve a focused delivery of electrosurgical energy between the two electrodes.

[0005] The current solution for dual site surgery, i.e. the simultaneous use of two electrosurgical devices, is generally to use two electrosurgical generators. This solution is inherently cumbersome and cost-prohibitive. Therefore, there is a need to independently control multiple ports of a single electrosurgical generator with a common return path. Summary of the Invention [Means for solving the problem]

[0006] The present disclosure provides an electrosurgical system including an electrosurgical generator having two radio frequency (RF) channels generated by two separate RF sources. Each of the sources includes a power supply configured to output DC power and an RF power inverter configured to output an RF waveform. The individual RF waveforms are supplied to a corresponding bipolar device. Each of the sources is controlled by its own controller, each coupled to a common clock source. The electrosurgical generator performs wideband measurements of the discontinuous or continuous signals of each source and simultaneously detects the mutual conductance and crosstalk between the RF sources. As used herein, mutual conductance is the current of an energy channel flowing through the contact impedance of the opposing channel, and crosstalk is the radiated interference between the energy channels in the electrosurgical generator.

[0007] According to one embodiment of the present disclosure, an electrosurgical generator is disclosed. The generator includes a first radio frequency source having a first power source configured to output a first DC waveform, a first radio frequency inverter coupled to the first power source and configured to generate a first interrogation waveform and a first radio frequency waveform from the first DC waveform, and a first controller configured to control the first radio frequency inverter to output the first radio frequency waveform based on a response of the first interrogation waveform. The generator also includes a second radio frequency source having a second power source configured to output a second DC waveform, a second radio frequency inverter coupled to the second power source and configured to generate the second interrogation waveform simultaneously with the first interrogation waveform and generate the second radio frequency waveform simultaneously with the first radio frequency waveform, and a second controller configured to control the second radio frequency inverter to output the second radio frequency waveform based on a response of the second interrogation waveform.

[0008] According to another embodiment of the present disclosure, an electrosurgical generator is disclosed. The system includes a first bipolar electrosurgical instrument and a second bipolar electrosurgical instrument. The system also includes an electrosurgical generator having a first radio frequency source including a first power source configured to output a first DC waveform and a first radio frequency inverter coupled to the first power source and the first bipolar electrosurgical instrument. The first radio frequency inverter is configured to generate a first interrogation waveform and a first radio frequency waveform from the first DC waveform. The first radio frequency source also includes a first controller configured to control the first radio frequency inverter to output the first radio frequency waveform based on a response of the first interrogation waveform. The generator also includes a second radio frequency source including a second power source configured to output a second DC waveform and a second radio frequency inverter coupled to the second power source and the second bipolar electrosurgical instrument. The second radio frequency inverter is configured to generate a second interrogation waveform concurrently with the first interrogation waveform and to generate the second radio frequency waveform concurrently with the first radio frequency waveform. The second radio frequency source also includes a second controller configured to control the second radio frequency inverter to output the second radio frequency waveform based on a response of the second interrogation waveform.

[0009] According to one aspect of any of the above embodiments, each of the first interrogation waveform and the second interrogation waveform is a pulsed radio frequency waveform comprising a plurality of pulses having a duration of about 10 μsec to about 1,000 μsec and a repetition rate of about 10 ms to about 50 ms.

[0010] According to another aspect of any of the above embodiments, the first radio frequency source further includes at least one first sensor configured to measure a first impedance based on the first interrogation waveform. The first controller is further configured to determine contact between a first electrosurgical device coupled to the first radio frequency source and tissue based on a comparison of the first impedance to an open circuit threshold. The first controller is further configured to control the first radio frequency inverter to output the first radio frequency waveform based on the comparison.

[0011] According to a further aspect of any of the above embodiments, the second radio frequency source further includes at least one second sensor configured to measure a second impedance based on the second interrogation waveform. The second controller is configured to determine contact between a second electrosurgical device coupled to the second radio frequency source and tissue based on a comparison of the second impedance to an open circuit threshold. The second controller is further configured to control the second radio frequency inverter to output the second radio frequency waveform based on the comparison.

[0012] According to yet another aspect of any of the above embodiments, the generator further includes a clock source coupled to the first controller and the second controller and configured to synchronize operation of the first controller and the second controller. For example, the present application provides the following: (Item 1) 1. An electrosurgical generator comprising: a first radio frequency source, a first power supply configured to output a first DC waveform; a first radio frequency inverter coupled to the first power source and configured to generate a first interrogation waveform and a first radio frequency waveform from the first DC waveform; and a first radio frequency source including a first controller configured to control the first radio frequency inverter to output the first radio frequency waveform based on a response of the first interrogation waveform; a second radio frequency source, a second power supply configured to output a second DC waveform; a second radio frequency inverter coupled to the second power source and configured to generate a second interrogation waveform simultaneously with the first interrogation waveform and to generate a second radio frequency waveform simultaneously with the first radio frequency waveform; and a second radio frequency source including a second controller configured to control the second radio frequency inverter to output the second radio frequency waveform based on a response of the second interrogation waveform; and (Item 2) 2. An electrosurgical generator as described in the preceding item, wherein each of the first interrogation waveform and the second interrogation waveform is a pulsed radio frequency waveform. (Item 3) 2. An electrosurgical generator according to any one of the preceding claims, wherein the pulsed radio frequency waveform comprises a plurality of pulses having a duration of about 10 μsec to about 1,000 μsec and a repetition rate of about 10 ms to about 50 ms. (Item 4) 2. The electrosurgical generator of claim 1, wherein the first radio frequency source further includes at least one first sensor configured to measure a first impedance based on the first interrogation waveform. (Item 5) 2. The electrosurgical generator of claim 1, wherein the first controller is further configured to determine contact between a first electrosurgical instrument coupled to the first radio frequency source and tissue based on a comparison of the first impedance to an open circuit threshold. (Item 6) 2. An electrosurgical generator as described in any one of the preceding items, wherein the first controller is further configured to control the first radio frequency inverter to output the first radio frequency waveform based on the comparison. (Item 7) 2. The electrosurgical generator of claim 1, wherein the second radio frequency source further includes at least one second sensor configured to measure a second impedance based on the second interrogation waveform. (Item 8) 2. The electrosurgical generator of claim 1, wherein the second controller is further configured to determine contact between a second electrosurgical instrument coupled to the second radio frequency source and tissue based on a comparison of the second impedance to an open circuit threshold. (Item 9) 2. An electrosurgical generator as described in any one of the preceding items, wherein the second controller is further configured to control the second radio frequency inverter to output the second radio frequency waveform based on the comparison. (Item 10) 2. The electrosurgical generator of claim 1, further comprising a clock source coupled to the first controller and the second controller and configured to synchronize operation of the first controller and the second controller. (Item 11) 1. An electrosurgical system comprising: a first bipolar electrosurgical instrument; a second bipolar electrosurgical instrument; and 1. An electrosurgical generator comprising: a first radio frequency source, a first power supply configured to output a first DC waveform; a first radio frequency inverter coupled to the first power source and to the first bipolar electrosurgical instrument, the first radio frequency inverter configured to generate a first interrogation waveform and a first radio frequency waveform from the first DC waveform; and a first radio frequency source including a first controller configured to control the first radio frequency inverter to output the first radio frequency waveform based on a response of the first interrogation waveform; a second radio frequency source, a second power supply configured to output a second DC waveform; a second radio frequency inverter coupled to the second power source and to the second bipolar electrosurgical instrument, the second radio frequency inverter configured to generate a second interrogation waveform concurrently with the first interrogation waveform and to generate a second radio frequency waveform concurrently with the first radio frequency waveform; an electrosurgical generator including a second radio frequency source including a second controller configured to control the second radio frequency inverter to output the second radio frequency waveform based on a response of the second interrogation waveform; and (Item 12) The electrosurgical system of the preceding item, wherein each of the first interrogation waveform and the second interrogation waveform is a pulsed radio frequency waveform. (Item 13) 2. The electrosurgical system of claim 1, wherein the pulsed radio frequency waveform comprises a plurality of pulses having a duration of about 10 μsec to about 1,000 μsec and a repetition rate of about 10 ms to about 50 ms. (Item 14) The electrosurgical system of any one of the preceding items, wherein the first radio frequency source further includes at least one first sensor configured to measure a first impedance based on the first interrogation waveform. (Item 15) 2. The electrosurgical system of claim 1, wherein the first controller is further configured to determine contact between the first bipolar electrosurgical device coupled to the first radio frequency source and tissue based on a comparison of the first impedance to an open circuit threshold. (Item 16) The electrosurgical system of any one of the preceding items, wherein the first controller is further configured to control the first radio frequency inverter to output the first radio frequency waveform based on the comparison. (Item 17) The electrosurgical system of any one of the preceding items, wherein the second radio frequency source further includes at least one second sensor configured to measure a second impedance based on the second interrogation waveform. (Item 18) The electrosurgical system of any one of the preceding items, wherein the second controller is further configured to determine contact between the second bipolar electrosurgical device coupled to the second radio frequency source and tissue based on a comparison of the second impedance to an open circuit threshold. (Item 19) The electrosurgical system of any one of the preceding items, wherein the second controller is further configured to control the second radio frequency inverter to output the second radio frequency waveform based on the comparison. (Item 20) 2. The electrosurgical system of claim 1, wherein the electrosurgical generator further includes a clock source coupled to the first controller and the second controller and configured to synchronize operation of the first controller and the second controller. (Summary) The electrosurgical generator includes a first radio frequency source having a first power supply configured to output a first DC waveform, a first radio frequency inverter coupled to the first power supply and configured to generate a first interrogation waveform and a first radio frequency waveform from the first DC waveform, and a first controller configured to control the first radio frequency inverter to output the first radio frequency waveform based on a response of the first interrogation waveform. The generator also includes a second radio frequency source having a second power supply configured to output a second DC waveform, a second radio frequency inverter coupled to the second power supply and configured to generate the second interrogation waveform concurrently with the first interrogation waveform and generate the second radio frequency waveform concurrently with the first radio frequency waveform, and a second controller configured to control the second radio frequency inverter to output the second radio frequency waveform based on a response of the second interrogation waveform. [Brief description of the drawings]

[0013] The present disclosure may be understood by reference to the accompanying drawings when considered in conjunction with the following detailed description.

[0014] [Figure 1] FIG. 1 is a perspective view of an electrosurgical system according to one embodiment of the present disclosure. [Diagram 2] FIG. 2 is a front view of the dual RF source electrosurgical generator of FIG. 1 in accordance with an embodiment of the present disclosure. [Diagram 3] 2 is a schematic diagram of the electrosurgical generator of FIG. 1 according to one embodiment of the present disclosure. [Figure 4] 2 is a schematic diagram of a clock source coupled to a first controller of a first RF source and a second controller of a second control source of the electrosurgical generator of FIG. 1 in accordance with the present disclosure; FIG. [Diagram 5] 2 is a frequency response plot of a continuous RF waveform generated by the electrosurgical generator of FIG. 1 in accordance with the present disclosure. [Figure 6] 2 is a frequency response plot of a discontinuous RF waveform produced by the electrosurgical generator of FIG. 1 in accordance with the present disclosure. [Figure 7] 2 is a flow chart of a method for operating the electrosurgical generator of FIG. 1 to detect tissue contact during auto-bipolar mode, according to one embodiment of the present disclosure. [Figure 8] 2 is a flowchart of a method for operating the electrosurgical generator of FIG. 1 to detect overcurrent and / or transconductance according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Embodiments of the presently disclosed electrosurgical system will now be described in detail with reference to the drawings, in which like reference numerals indicate identical or corresponding elements in each of the several views. As used herein, the term "distal" refers to that portion of an associated surgical instrument that is closer to the patient and the term "proximal" refers to that portion that is further from the patient.

[0016] The term "application" may include a computer program designed to perform a function, task, or activity for the benefit of a user. An application may refer to software that runs locally or remotely, for example, as a standalone program or in a web browser, or other software that would be understood by one of ordinary skill in the art to be an application. An application may run on a controller or on a user device, including, for example, a mobile device, an IOT device, a server system, or any programmable logic device.

[0017] In the following description, well-known functions or configurations are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Those skilled in the art will understand that the present disclosure can be adapted for use with either endoscopic instruments, laparoscopic instruments, or open instruments. It should also be understood that different electrical and mechanical connections and other considerations may apply to each particular type of instrument.

[0018] Electrosurgical generators according to the present disclosure may be used in monopolar and / or bipolar electrosurgical procedures, including, for example, cutting, coagulation, ablation, and vessel sealing procedures. The generator may include multiple outputs for interfacing with a variety of ultrasonic and electrosurgical instruments (e.g., ultrasonic dissectors and hemostats, monopolar instruments, return electrode pads, bipolar electrosurgical forceps, foot switches, etc.). Additionally, the generator may include electronic circuitry configured to generate radio frequency energy particularly suitable for powering ultrasonic instruments and electrosurgical devices operating in a variety of electrosurgical modes (e.g., cutting, mixing, coagulation, division with hemostasis, electrodisruption, spraying, etc.) and procedures (e.g., monopolar, bipolar, vessel sealing).

[0019] Referring to FIG. 1 , there is shown an electrosurgical system 10 including one or more bipolar electrosurgical instruments 20′ and 20″, shown as forceps having a pair of electrodes 23a′ and 23b′ and 23a″ and 23b″, respectively, for treating tissue of a patient. In an embodiment, the bipolar electrosurgical instruments 20′ and 20″ may be a pair of forceps. The instruments 20′ and 20″ are coupled to a generator 100 via cables 24′ and 24″. The generator 100 is a dual source RF generator configured to supply separate RF waveforms to each of the instruments 20′ and 20″ from individual RF sources.

[0020] Referring to FIG. 2, a front side 102 of the generator 100 is shown. The generator 100 may include multiple ports 110, 112, 114, 116 for accommodating various types of electrosurgical equipment, and a port 118 for coupling to a return electrode pad. The generator 100 includes a display 120 for providing various output information to a user (e.g., intensity settings, treatment completion indicators, etc.). The display 120 is a touch screen configured to display menus corresponding to the equipment (e.g., bipolar electrosurgical equipment 20′ and 20″, electrosurgical forceps, etc.). Thus, a user adjusts inputs by simply touching a corresponding menu option. The generator 100 also includes suitable input controls 122 (e.g., buttons, activators, switches, touch screen, etc.) for controlling the generator 100.

[0021] The generator 100 is configured to operate in various modes and is configured to output a bipolar waveform based on the selected mode. Each mode operates based on a pre-programmed power curve that determines how much power is output by the generator 100 at various impedance ranges of the load (e.g., tissue). Each of the power curves includes control ranges of power, voltage, and current that are defined by the user selected intensity setting and the minimum impedance of the measured load.

[0022] The first and second RF waveforms may be either continuous or discontinuous and may have a carrier frequency of about 200 kHz to about 500 kHz. As used herein, a continuous waveform is a waveform having a 100% duty cycle. In embodiments, a continuous waveform is used to provide a cutting effect on tissue. Conversely, a discontinuous waveform is a waveform having a non-continuous duty cycle, e.g., less than 100%. In embodiments, a discontinuous waveform is used to provide a coagulation effect on tissue.

[0023] 3, the generator 100 includes a dual source RF architecture in which each RF source is supplied by an individual and separate RF inverter, each powered by an individual and separate DC power source. More specifically, the generator 100 includes a first RF source 202 and a second source 302. Each of the sources 202 and 302 includes a first controller 204 and a second controller 304, a first power source 206 and a second power source 306, and a first RF inverter 208 and a second RF inverter 308. The power sources 206 and 306 may be high voltage DC power sources connected to a common AC power source (e.g., line voltage) and provide high voltage DC power to the respective RF inverters 208 and 308, which then convert the DC power to a first RF waveform and a second RF waveform through the respective active terminals 210 and 310. Energy is returned thereto via first and second return terminals 212 and 312, respectively. In particular, electrosurgical energy for energizing bipolar electrosurgical instruments 20' and 20'' is delivered via ports 114 and 116, each of which is coupled to active and return terminals 210 and 212, and active and return terminals 310 and 312, respectively.

[0024] The active terminal 210 and the return terminal 212 are coupled to the RF inverter 208 through an isolation transformer 214. The isolation transformer 214 includes a primary winding 214a coupled to the RF inverter 208 and a secondary winding 214b coupled to the active terminal 210 and the return terminal 212. Similarly, the active terminal 310 and the return terminal 312 are coupled to the RF inverter 308 through an isolation transformer 314. The isolation transformer 314 includes a primary winding 314a coupled to the RF inverter 308 and a secondary winding 314b coupled to the active terminal 310 and the return terminal 312.

[0025] The RF inverters 208 and 308 are configured to operate in multiple modes during which the generator 100 outputs a corresponding waveform having a particular duty cycle, peak voltage, crest factor, etc. In other embodiments, it is envisioned that the generator 100 may be based on other types of suitable power supply topologies. The RF inverters 208 and 308 may be resonant RF amplifiers as shown or non-resonant RF amplifiers. A non-resonant RF amplifier, as used herein, refers to an amplifier that lacks any conditioning components, i.e., conductors, capacitors, etc., disposed between the RF inverter and a load, e.g., tissue.

[0026] The controllers 204 and 304 may include a processor (not shown) operatively connected to a memory (not shown), which may include one or more of volatile, non-volatile, magnetic, optical, or electrical media, such as read-only memory (ROM), random access memory (RAM), electrically erasable programmable ROM (EEPROM), non-volatile RAM (NVRAM), or flash memory. The processor may be any suitable processor (e.g., control circuitry) adapted to perform the operations, calculations, and / or set of instructions described in this disclosure, including, but not limited to, a hardware processor, a field programmable gate array (FPGA), a digital signal processor (DSP), a central processing unit (CPU), a microprocessor, and combinations thereof. Those skilled in the art will appreciate that the processor may be substituted by using any logical processor (e.g., control circuitry) adapted to perform the calculations and / or set of instructions described herein.

[0027] Each of the controllers 204 and 304 is operatively connected to a respective power source 206 and 306 and / or RF inverter 208 and 308, enabling the processor to control the output of the first RF source 202 and second source 302 of the generator 100 according to either an open and / or closed control loop scheme. A closed loop control scheme is a feedback control loop in which multiple sensors measure various tissue and energy characteristics (e.g., tissue impedance, tissue temperature, output power, current and / or voltage, etc.) and provide feedback to each of the controllers 204 and 304. The controllers 204 and 304 then control the respective power sources 206 and 306 and / or RF inverters 208 and 308, respectively, which adjust the DC and / or RF waveforms.

[0028] The generator 100 according to the present disclosure may also include a number of sensors 216 and 316 that each monitor the output of the first RF source 202 and the second RF source 302 of the generator 100. The sensors 216 and 316 may be any suitable voltage, current, power, and impedance sensors. In the embodiment shown in FIG. 3, the sensor 216 is coupled to the leads 220a and 220b of the RF inverter 208. The leads 220a and 220b couple the RF inverter 208 to the primary winding 214a of the transformer 214. The sensor 316 is coupled to the leads 320a and 320b of the RF inverter 308. The leads 320a and 320b couple the RF inverter 308 to the primary winding 314a of the transformer 314. Thus, the sensors 216 and 316 are configured to sense the voltage, current, and other electrical characteristics of the energy supplied to the active terminals 210 and 310 and the return terminals 212 and 312 .

[0029] In further embodiments, sensors 216 and 316 may be coupled to power sources 206 and 306 and configured to sense characteristics of the DC current supplied to RF inverters 208 and 308. Controllers 204 and 304 also receive input signals from display 120 and input controls 122 of generator 100 and / or equipment 20' and 20". Controllers 204 and 304 adjust the power output by generator 100 and / or perform other control functions for generator 100 in response to the input signals.

[0030] RF inverters 208 and 308 include multiple switching elements 228a-228d and 328a-328d, respectively, arranged in an H-bridge topology. In embodiments, RF inverters 208 and 308 may be configured according to any suitable topology, including but not limited to half-bridge, full-bridge, push-pull, etc. Suitable switching elements include voltage controlled devices such as transistors, field effect transistors (FETs), combinations thereof, etc. In embodiments, the FETs may be formed from gallium nitride, aluminum nitride, boron nitride, silicon carbide, or any other suitable wide bandgap material.

[0031] The controllers 204 and 304 are in communication with the respective RF inverters 208 and 308, particularly the switching elements 228a-228d and 328a-328d. The controllers 204 and 304 are configured to output control signals, which may be pulse width modulated ("PWM") signals, to the switching elements 228a-228d and 328a-328d. In particular, the controller 204 is configured to modulate the control signal d1 provided to the switching elements 228a-228d of the RF inverter 208, and the controller 304 is configured to modulate the control signal d2 provided to the switching elements 328a-328d of the RF inverter 308. The control signals d1 and d2 provide PWM signals that operate the RF inverters 208 and 308 at their respective selected carrier frequencies. Additionally, the controllers 204 and 304 are configured to calculate power characteristics of the output of the first RF source 202 and the second source 302 of the generator 100 and control the output of the first RF source 202 and the second source 302 based at least in part on the measured power characteristics, including but not limited to the voltage, current, and power at the output of the RF inverters 208 and 308.

[0032] 3 and 4, each of the controllers 204 and 304 is coupled to a clock source 340 that acts as a common frequency source for each of the controllers 204 and 304, and thus the controllers 204 and 304 are synchronized. The clock source 340 is an electronic oscillator circuit that generates a clock signal for synchronizing the operation of the controllers 204 and 304. In particular, the sampling operations of the controllers 204 and 304 are synchronized. Each of the controllers 204 and 304 generates an RF waveform based on the clock signal from the clock source 340 and the selected mode. Thus, when a user selects one of the electrosurgical modes, each of the controllers 204 and 304 outputs first and second control signals that are used to control the respective RF inverters 208 and 308 to output first and second RF waveforms corresponding to the selected mode. The selected modes for each of the first RF source 202 and the second source 302, and the corresponding RF waveforms, may be the same or different.

[0033] The RF waveforms have different carrier frequencies, such that the first RF waveform has a first carrier frequency and the second RF waveform has a second carrier frequency. The two different carrier frequencies are selected so that the controllers 204 and 304 can discriminate or separate the measurement data in the frequency domain. The measurement data is collected by the sensors 216 and 316 that monitor the output of the first RF source 202 and the second source 302. The controllers 204 and 304 analyze the respective first and second RF waveforms using any suitable bandpass technique or any technique that converts the measurement data into the frequency domain, such as a discrete Fourier transform (DFT) and a fast Fourier transform (FFT). In an embodiment, the controllers 204 and 304 may use an array of Goertzel filters for continuous waveforms (e.g., those used during the cutting mode) oriented at the carrier frequency of the RF waveform and its harmonics. For discontinuous waveforms, the Goertzel filters are oriented at the repetition rate and harmonics of the repetition frequency of the waveform being analyzed. The filtering of the measurement data may be performed by an application, such as software instructions, executable by the controllers 204 and 304 .

[0034] The frequencies of the first and second RF waveforms are selected to provide sufficient channel separation between the carrier frequencies of the first and second RF waveforms as determined by a bandpass Goertzel filter. Referring to frequency response plot 350 of Figure 5, the frequency of the opposing RF port of the continuous waveform is selected to be at a null point in the frequency response. This maximizes source-to-source separation.

[0035] Referring to FIG. 6, which shows a frequency response plot 360 of a discontinuous waveform, separate Goertzel filters are directed at the fundamental repetition rate and the even and odd harmonics of the RF waveform being analyzed. Since the fundamental frequencies are not perfectly orthogonal, there is an overlap of certain harmonics. The overlap of the sets of harmonics creates a discontinuity in the Goertzel array plot. This is used to detect if significant transconductance from one RF source occurs at the sensor 216 or 316 of another RF source. If it is desired to separate sources that contain combined information in only one of the harmonics, the unaffected harmonic is used in combination with a certain percentage of the affected harmonic. The separate transconductance information is used as a dose monitor to detect excessive transconductance situations.

[0036] In embodiments where both the first and second RF waveforms are discontinuous, the limited frequency space may be restrictive. The discontinuous waveforms may have a repetition rate of about 20 KHz to about 490 KHz. The repetition rate does not provide a completely orthogonal solution from a signal processing perspective. The technique for determining the power value of each of the first RF source 202 and the second source 302 to be used for independent control depends on the level of transconductance. The transconductance causes the actual power to be stored in the contact impedance. Thus, the power to control is based on the sum of the transconductance power stored in the contact impedance site and the port source power stored in the contact impedance. In embodiments, the non-contact tissue impedance and the power stored in the return electrode pad 26 may also be included in the overall calibration of a particular RF port. If frequency discrimination is used for power control, prior to using the generator 100, the instrument 20' and 20", and return electrode pad 26 are subjected to a calibration procedure that takes into account both the cable compensation of the supply lines 24' and 24", and the return line 28, as well as harmonic overlap and transconductance. Transconductance may also be monitored as a mitigation measure for potential dose errors.

[0037] In an embodiment, where one of the first and second RF waveforms is continuous and the other is discontinuous, the continuous RF waveform may be at a higher Goertzel frequency of approximately 481 KHz and the discontinuous RF waveform may be at a lower frequency of approximately 433 KHz such that little interference occurs between the sources due to the Goertzel frequency response being divisible by 45 (see Figures 5 and 6) and the concentration of discontinuous energy being at or below its carrier frequency of 433 KHz.

[0038] In embodiments where the first and second RF waveforms are continuous, the preselected unique carrier frequencies of 433KHz and 481KHz also follow the coherent sampling rule, which is used to separate the continuous RF sources in conjunction with a Goertzel filter to provide attenuation of constructively or destructively interfering signals from the other source. The bandpass filter provides a signal passband region and lower / upper signal rejection regions. The level of rejection is variable and based on the type of bandpass filter designed. The finite impulse response (FIR) filter provides a sine function (sin x / x) type amplitude vs. frequency response. A computationally efficient Goertzel filter implementation acts like a sampling function, as shown in plots 350 and 360 of Figures 5 and 6.

[0039] The generator 100 is configured to operate in an auto-bipolar mode during which each of the first RF source 202 and the RF second source 302 outputs any suitable bipolar RF waveform upon detection of tissue contact. A user may configure each of the first RF source 202 and the RF second source 302 during this mode to set the power level and set a delay time for initiating RF delivery after confirming that the bipolar electrosurgical devices 20' and 20'' are in contact with tissue. In this mode, the generator outputs a low power interrogation pulse waveform to measure impedance and determine tissue contact. The interrogation waveform may be from about 1 W to about 5 W, may be from about 10 μs to about 1,000 μs in duration, and may be repeated every 10 ms to about 50 ms. Upon detecting impedance indicative of tissue contact, the generator 100 outputs energy via the connected bipolar devices 20' and 20'' after a user-selectable delay time.

[0040] With reference to FIG. 7, a method for controlling the generator 100 is disclosed. The method provides for simultaneous dual actuation of the first RF source 202 and the RF second source 302. Initially, each of the first RF source 202 and the second RF source 302 is configured by selecting an auto-bipolar mode. As described above, each mode is associated with a predefined RF waveform, which may be continuous or discontinuous, and is based on the desired tissue effect. The RF waveform of the auto-bipolar mode may be a discontinuous waveform. The user also individually configured each of the first RF source 202 and the second RF source 302 to include a power level of the RF waveform and a delay for generation of the RF waveform after detection of tissue contact.

[0041] In operation, each of the RF first source 202 and the RF second source 302 continuously outputs a first interrogation waveform and a second interrogation waveform while the mode is active. The first and second interrogation waveforms are separated and used by the sensors 216 and 316 to measure the impedance, if any, of the tissue being contacted by each of the devices 20' and 20''. Each of the processors 204 and 304 continuously compares the impedance responsive to the first and second interrogation waveforms to a predetermined threshold (which may be 1000 Ω) indicative of a resistive load present (e.g., not an open circuit). In a further embodiment, the impedance may be compared to a lower threshold indicative of a short circuit, which may be about 10 ohms (Ω) to about 50 Ω.

[0042] The processors 204 and 304 utilize signal processing and / or time sharing techniques to distinguish between the first and second simultaneously activated interrogation waveforms. The processors 204 and 304 also determine the level of transconductance between the first RF source 202 and the second RF source 302. The carrier frequency of the interrogation waveform is such that the carrier frequency provides coherent sampling under the update rate of the time-critical power calculation, providing effective frequency discrimination combined with transconductance detection. The carrier frequency ratio can be varied between a 45:50 Goertzel ratio and a 49:51 Goertzel ratio to provide different response speeds for tissue contact detection, i.e., distinguishing from an open circuit. Time-cascaded Goertzel calculations can also be used to provide shorter time intervals between the power calculations of the algorithm.

[0043] In an embodiment, the optimal frequencies of the first and second interrogation waveforms may be determined by scanning the frequency response of the first and second RF sources 202 and 302 and identifying noise frequencies. After identifying the noise carrier frequencies, quieter frequencies are selected to avoid corruption of the first and second interrogation waveforms, thereby avoiding false detection of tissue contact.

[0044] In further embodiments, the pulses of the first and second interrogation waveforms may be separated in time such that they do not overlap. The duration of each pulse of the first and second interrogation waveforms (e.g., about 10 μsec to about 1,000 μsec) is shorter than the off time between pulses (e.g., every about 10 ms to about 50 ms), so that the pulses may be synchronized to any time slot within the off period of the other waveform such that the pulses do not occur at the same time.

[0045] Referring to FIG. 8, a method of monitoring the output of the first RF source 202 and the RF second source 302, including an interrogation waveform and an RF bipolar waveform for overcurrent and transconductance. When the processors 204 and 304 determine that the devices 20′ and 20″ are in contact with tissue, the processors 204 and 304 signal the first RF source 202 and / or the RF second source 302 to output first and second bipolar RF waveforms to treat the tissue depending on which of the devices 20′ or 20″ has contacted the tissue. Thus, if only one of the devices 20′ or 20″ is determined to have contacted tissue based on the detection method of FIG. 7, only the corresponding first or second RF source 202 or 302 is energized to output a bipolar waveform to treat the tissue. The other one of the first or second RF sources 202 or 302 remains in an interrogation mode until the user exits the auto bipolar mode or tissue contact is detected.

[0046] If both interrogation waveforms confirm tissue contact, the first and second bipolar RF waveforms may be delivered simultaneously. During the simultaneous bipolar RF waveform transmission, the sensors 216 and 316 measure characteristics of the first and second RF waveforms. The bipolar RF waveform carrier frequency and coagulation repetition rate may be selected to provide coherent sampling under time-critical power calculation update rates.

[0047] The sensors 216 and 316 in conjunction with the respective controllers 204 and 304 perform wideband measurements of each of the first and second RF waveforms and simultaneously detect the transconductance between the first RF source 202 and the second RF source 302 .

[0048] Each of the controllers 204 and 304 also utilizes signal processing techniques, i.e., the Goertzel array plot described above, to discriminate between the simultaneously activated first RF source 202 and second RF source 302. The controllers 204 and 304 are also configured to determine the level of transconductance, if any, between the first RF source 202 and the second RF source 302 using signal processing discrimination techniques. After the level of transconductance is determined, the level of transconductance is used as a safety mitigation measure during simultaneous bipolar RF operation, i.e., as a dose error monitor. In particular, upon detection of transconductance by either the controller 204 or 304, each of the controllers 204 and 304 is configured to warn and / or shut down both the first RF source 202 and the second RF source 302 in response to a dose error in transconductance.

[0049] Although several embodiments of the present disclosure have been shown in the drawings and / or described herein, the present disclosure is not intended to be limited to these embodiments, since the present disclosure is broad enough to be tolerated by the art, and the specification is intended to be read in the same manner. Therefore, the above description should not be interpreted as limiting, but merely as exemplification of certain embodiments. Those skilled in the art will envision other modifications within the scope of the claims appended hereto.

Claims

1. 1. An electrosurgical generator comprising: a first radio frequency source, a first power supply configured to output a first DC waveform; a first radio frequency inverter coupled to the first power source and configured to generate a first interrogation waveform and a first radio frequency waveform from the first DC waveform; and a first controller configured to control the first radio frequency inverter to output the first radio frequency waveform based on a response of the first interrogation waveform; a first radio frequency source including: a second radio frequency source, a second power supply configured to output a second DC waveform; a second radio frequency inverter coupled to the second power source and configured to generate a second interrogation waveform concurrently with the first interrogation waveform and to generate a second radio frequency waveform concurrently with the first radio frequency waveform; and a second controller configured to control the second radio frequency inverter to output the second radio frequency waveform based on a response of the second interrogation waveform. a second radio frequency source including 1. An electrosurgical generator including:

2. An electrosurgical generator according to claim 1 , wherein each of the first interrogation waveform and the second interrogation waveform is a pulsed radio frequency waveform.

3. 3. An electrosurgical generator according to claim 2, wherein the pulsed radio frequency waveform comprises a plurality of pulses having a duration between 10 μsec and 1,000 μsec and repeated every 10 milliseconds to 50 milliseconds.

4. An electrosurgical generator according to claim 1 , wherein the first radio frequency source further includes at least one first sensor configured to measure a first impedance based on the first interrogation waveform.

5. 5. The electrosurgical generator of claim 4, wherein the first controller is further configured to determine contact between a first electrosurgical instrument coupled to the first radio frequency source and tissue based on a comparison of the first impedance to an open circuit threshold.

6. An electrosurgical generator according to claim 5, wherein the first controller is further configured to control the first radio frequency inverter to output the first radio frequency waveform based on the comparison.

7. An electrosurgical generator according to claim 6, wherein the second radio frequency source further includes at least one second sensor configured to measure a second impedance based on the second interrogation waveform.

8. 8. The electrosurgical generator of claim 7, wherein the second controller is further configured to determine contact between a second electrosurgical instrument coupled to the second radio frequency source and tissue based on a comparison of the second impedance to an open circuit threshold.

9. An electrosurgical generator according to claim 8, wherein the second controller is further configured to control the second radio frequency inverter to output the second radio frequency waveform based on the comparison.

10. 10. An electrosurgical generator according to claim 1, further comprising a clock source coupled to the first controller and the second controller and configured to synchronize operation of the first controller and the second controller.

11. 1. An electrosurgical system comprising: a first bipolar electrosurgical instrument; a second bipolar electrosurgical instrument; and 1. An electrosurgical generator comprising: a first radio frequency source, a first power supply configured to output a first DC waveform; a first radio frequency inverter coupled to the first power source and to the first bipolar electrosurgical instrument, the first radio frequency inverter configured to generate a first interrogation waveform and a first radio frequency waveform from the first DC waveform; and a first controller configured to control the first radio frequency inverter to output the first radio frequency waveform based on a response of the first interrogation waveform; a first radio frequency source including: a second radio frequency source, a second power supply configured to output a second DC waveform; a second radio frequency inverter coupled to the second power source and to the second bipolar electrosurgical instrument, the second radio frequency inverter configured to generate a second interrogation waveform concurrently with the first interrogation waveform and to generate a second radio frequency waveform concurrently with the first radio frequency waveform; a second controller configured to control the second radio frequency inverter to output the second radio frequency waveform based on a response of the second interrogation waveform. a second radio frequency source including an electrosurgical generator including 1. An electrosurgical system comprising:

12. The electrosurgical system of claim 11 , wherein each of the first interrogation waveform and the second interrogation waveform is a pulsed radio frequency waveform.

13. The electrosurgical system of claim 12, wherein the pulsed radio frequency waveform comprises a plurality of pulses having a duration between 10 μsec and 1,000 μsec and repeated every 10 ms to 50 ms.

14. The electrosurgical system of claim 11 , wherein the first radio frequency source further includes at least one first sensor configured to measure a first impedance based on the first interrogation waveform.

15. 15. The electrosurgical system of claim 14, wherein the first controller is further configured to determine contact between the first bipolar electrosurgical device coupled to the first radio frequency source and tissue based on a comparison of the first impedance to an open circuit threshold.

16. The electrosurgical system of claim 15 , wherein the first controller is further configured to control the first radio frequency inverter to output the first radio frequency waveform based on the comparison.

17. The electrosurgical system of claim 16, wherein the second radio frequency source further includes at least one second sensor configured to measure a second impedance based on the second interrogation waveform.

18. 18. The electrosurgical system of claim 17, wherein the second controller is further configured to determine contact between the second bipolar electrosurgical device coupled to the second radio frequency source and tissue based on a comparison of the second impedance to an open circuit threshold.

19. The electrosurgical system of claim 18 , wherein the second controller is further configured to control the second radio frequency inverter to output the second radio frequency waveform based on the comparison.

20. 12. The electrosurgical system of claim 11, wherein the electrosurgical generator further includes a clock source coupled to the first controller and the second controller and configured to synchronize operation of the first controller and the second controller.

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