Surgical system

Abstract

The present disclosure relates to a surgical system comprising: a control circuit; and an output circuit coupled to the control circuit and configured to deliver energy to an output terminal for delivery to a patient, the output terminal configured to be coupled to an electrosurgical apparatus having two jaws with corresponding electrodes, wherein the control circuit is configured to: deliver a first therapeutic electrosurgical energy pulse to biological tissue in electrical communication with the two electrodes of the electrosurgical apparatus, wherein the first therapeutic electrosurgical energy pulse is followed by a first dwell time; determine an amount of energy delivered to the jaws during the first therapeutic electrosurgical energy pulse; calculate a second dwell time based on the determined amount of energy delivered during the first therapeutic electrosurgical energy pulse, wherein the second dwell time is less than the first dwell time; and deliver a second therapeutic electrosurgical energy to the biological tissue.

Description

[0001] This application is a continuation-in-part of International Patent Application No. PCT / US2020 / 031857, filed May 7, 2020, which claims priority to U.S. Provisional Patent Application No. 62 / 857, 1 12, filed June 10, 2019, and U.S. Provisional Patent Application No. 62 / 857, 1 13, filed June 10, 2019, each of which is incorporated by reference in its entirety.

[0002] CLAIM OF PRIORITY

[0003] This application is related to (1) U.S. Provisional Application No. 62 / 845,647, entitled “ELECTROSURGICALLY SEALING BIOLOGICAL TISSUE BY CONTROLLING POWER PROVIDED THERETO,” by Kester J. Batchelor et al. and filed on May 9, 2019, and to (2) U.S. Provisional Application No. 62 / 905,318, entitled “ELECTROSURGICALLY SEALING BIOLOGICAL TISSUE BY CONTROLLING POWER PROVIDED THERETO,” by Kester J. Batchelor et al. and filed on September 24, 2019, and to (3) U.S. Provisional Application No. 62 / 905,366, entitled “CORRECTING TISSUE RESISTANCE MEASUREMENTS USING TEMPORAL DATA,” by Huisun Wang et al. and filed on September 24, 2019, and to (4) U.S. Provisional Application No. 62 / 905,337, entitled “PREDICTIVE PHASE CONTROL OF AN ELECTROTHERAPEUTIC PROCEDURE,” by Huisun Wang et al. and filed on September 24, 2019, and to (5) U.S. Provisional Application No. 62 / 905,345, entitled “PULSED ELECTRICAL POWER PROVIDED TO SEALED TISSUE TO REDUCE TISSUE STICKING,” by Huisun Wang et al. and filed on September 24, 2019, and to (6) U.S. Provisional Application No. 62 / 905,360, entitled “IMPEDANCE PHASE DETECTION FOR SHORT CIRCUIT PREDICTION,” by Wayne Williams et al. and filed on September 24, 2019, the entire contents of each of which are hereby incorporated by reference in their entireties and priority to each of which is claimed herein. BACKGROUND

[0004] Electrosurgery is the application of electrical signals—electrotreatment signals—to produce changes in biological tissue of a surgical patient in some manner. Various electrosurgical techniques are used to cut, coagulate, desiccate, or cauterize biological tissue. These and other techniques can be performed during various medical procedures, such as laparoscopic surgery. These medical procedures include: appendectomy, cholecystectomy, colectomy, cystectomy, gastric banding, gastric bypass, hernia repair, nephrectomy, Nissen fundoplication, prostatectomy, sleeve gastrectomy, etc. Each of these medical procedures can have one or more electrotreatment phases, such as an interrogation phase, a heating phase, a desiccation phase, a cauterization phase, etc.

[0005] Electrotreatment signals used in such medical procedures can be generated by an electrosurgical generator and then provided to biological tissue via an electrosurgical instrument, which can be electrically connected to the electrosurgical generator. The electrosurgical instrument can be configured to mechanically and electrically engage the biological tissue to which the electrotreatment signals are provided. Various types of such electrosurgical instruments can be employed, including, for example, various types of forceps, conductive spatulas, electrical pads, etc.

[0006] Different medical procedures can implement different electrotreatment signals in order to achieve results specific to these different medical procedures. Various electrical metrics of the electrotreatment signals provided to the engaged biological tissue can be used to characterize these electrotreatment signals. These electrical metrics include: polarity (monopolar, bipolar), AC and / or DC, frequency, signal amplitude, rise and decay curves, etc. The electrosurgical generator that generates these various electrotreatment signals can control one or more of these electrical metrics in order to provide electrotreatment signals that produce effective results in the biological tissue engaged by the electrosurgical instrument. SUMMARY

[0007] Apparatuses and related methods relate to systems for providing controlled electrical power to biological tissue. An electrosurgical system includes forceps having opposable jaw members configured to open and close. The forceps also have a handpiece having a clamping lever configured to cause the opposable jaw members to open and close. The opposable jaw members, when closed, are configured to clamp biological tissue between the opposable jaw members in a manner that provides electrical communication between the opposable jaw members via the clamped biological tissue. The electrosurgical system also includes an electrosurgical generator electrically couplable to the forceps. The electrosurgical generator includes an electrical energy source in electrical communication with the opposable jaw members when the electrosurgical generator is electrically coupled to the forceps. The electrical energy source is configured to generate electrotreatment signals. The electrosurgical generator includes control circuitry configured to cause the electrical energy source to provide the electrotreatment signals to the clamped biological tissue during an electrotreatment phase. The electrical power of the provided electrotreatment signals is controlled in accordance with an electrotreatment protocol.

[0008] According to one aspect of the present application, there is provided a surgical system comprising: a control circuit; and

[0009] an output circuit coupled to the control circuit and configured to deliver energy to an output terminal for delivery to a patient, the output terminal configured to be coupled to an electrosurgical device having two jaws with corresponding electrodes, wherein the control circuit is configured to: deliver a first therapeutic electrosurgical energy pulse to biological tissue in electrical communication with the two electrodes of the electrosurgical device, wherein the first therapeutic electrosurgical energy pulse is followed by a first dwell time; determine an amount of energy delivered to the jaws during the first therapeutic electrosurgical energy pulse; calculate a second dwell time based on the determined amount of energy delivered during the first therapeutic electrosurgical energy pulse, wherein the second dwell time is less than the first dwell time; and deliver a second therapeutic electrosurgical energy pulse to the biological tissue, wherein the second therapeutic electrosurgical energy pulse is followed by the second dwell time.

[0010] According to another aspect of the present application, there is provided a surgical system comprising: a control circuit; and an output circuit coupled to the control circuit and configured to deliver energy to an output terminal for delivery to a patient, the output terminal configured to be coupled to an electrosurgical device having two jaws with corresponding electrodes, wherein the control circuit is configured to: deliver a first therapeutic electrosurgical energy pulse to biological tissue in electrical communication with the two electrodes of the electrosurgical device, wherein the first therapeutic electrosurgical energy pulse is followed by a first dwell time; start a timer upon delivery of the first therapeutic electrosurgical energy pulse; determine that the biological tissue has boiled and stop the timer upon determining that the biological tissue has boiled; compare the timer to one or more values; calculate a second dwell time based on the comparison, wherein the second dwell time is less than the first dwell time; and deliver a second therapeutic electrosurgical energy pulse to the biological tissue, wherein the second therapeutic electrosurgical energy pulse is followed by the second dwell time.

[0011] According to another aspect of the present disclosure, there is provided a surgical system comprising: a control circuit; and an output circuit coupled to the control circuit and configured to deliver energy to an output terminal for delivery to a patient, the output terminal configured to be coupled to an electrosurgical apparatus having two jaws with corresponding electrodes, wherein the control circuit is configured to: deliver a first therapeutic electrosurgical energy pulse to biological tissue in electrical communication with the two electrodes of the electrosurgical apparatus, wherein the first therapeutic electrosurgical energy pulse is followed by a first dwell time; determine an amount of electrosurgical current delivered during the first therapeutic electrosurgical energy pulse; calculate a second dwell time based on the determined amount of electrosurgical current delivered during the first therapeutic electrosurgical energy pulse, wherein the second dwell time is less than the first dwell time; and deliver a second therapeutic electrosurgical energy pulse to the biological tissue, wherein the second therapeutic electrosurgical energy pulse is followed by the second dwell time.

[0012] Some examples relate to an electrosurgical generator for providing controlled electrical power to biological tissue engaged by an electrosurgical instrument. The electrosurgical generator includes an electrical connector configured to electrically couple the electrosurgical instrument to the electrosurgical generator so as to provide electrical communication between the electrosurgical generator and the engaged biological tissue. The electrosurgical generator includes an electrical energy source electrically coupled to the electrical connector and configured to generate an electrical therapy signal. The electrosurgical generator also includes a control circuit configured to cause the electrical energy source to provide the electrical therapy signal to the engaged biological tissue during an electrical therapy phase. The electrical power of the electrical therapy signal provided to the engaged biological tissue is controlled according to an electrical therapy regimen.

[0013] Some examples relate to a method for providing controlled electrical power to biological tissue engaged by an electrosurgical instrument. The method includes the step of engaging the biological tissue via the electrosurgical instrument in a manner that provides electrical communication between the electrosurgical instrument and the engaged biological tissue. The method proceeds to the step of providing an electrical therapy signal to the engaged biological tissue via an electrical energy source in electrical communication with the electrosurgical instrument during an electrical therapy phase. The method also includes the step of controlling the electrical power of the provided electrical therapy signal according to an electrical therapy regimen. BRIEF DESCRIPTION OF DRAWINGS

[0014] FIG. 1 is a perspective view of an electrosurgical system for providing electrical therapy to biological tissue of a surgical patient.

[0015] FIG. 2 is a block diagram of an electrosurgical system for sealing biological tissue engaged by an electrosurgical instrument.

[0016] FIG. 3A-3B is a flowchart of a method for sealing biological tissue engaged by an electrosurgical instrument.

[0017] FIG. 4 is a plot depicting an example of an electrical power regime for controlling electrical power provided to enclosed biological tissue.

[0018] FIG. 5 is a flowchart depicting an example of an open-circuit check technique that can be used in a surgical system.

[0019] FIG. 6 is a flowchart of a biological tissue enclosure method using an electrical power regime corresponding to a size of biological tissue engaged with an electrosurgical instrument.

[0020] FIG. 7A is a plot depicting measured tissue resistance as a function of jaw temperature for forceps.

[0021] FIG. 7B is a plot depicting jaw temperature versus time after termination of power application.

[0022] FIG. 8 is a plot depicting resistance compensation versus time after power application.

[0023] FIG. 9 is a flowchart depicting a method for compensating for measured tissue resistance as a function of time after power application.

[0024] FIG. 10A-10D is a plot of an electrical parameter of an electrotherapy signal of an electrotherapy having an adherent reduction portion that is pulsed.

[0025] FIG. 11 is a flowchart of a method for reducing adherence between biological tissue and an electrosurgical instrument.

[0026] FIG. 12 is a plot depicting an example of an impedance-angle / time relationship for biological tissue with and without a metallic object.

[0027] FIG. 13 is a flowchart of a method for determining whether a metallic object is present in biological tissue engaged by an electrosurgical instrument.

[0028] FIG. 14 is a flowchart depicting an example of a double boundary technique that can be used in a surgical system.

[0029] FIG. 15 is a flowchart depicting an example of an open-circuit check technique that can be used in a surgical system.

[0030] FIG. 16 is a flowchart depicting another example of an open-circuit check technique that can be used in a surgical system.

[0031] FIG. 17is a flowchart depicting an example of a power correction technique that can be used in a surgical system.

[0032] FIG. 18 is a simplified block diagram of an example of a combined ultrasound energy and electrosurgical energy system that can implement various techniques of the present disclosure.

[0033] FIG. 19 is a flowchart depicting an example of a reduced thermal margin technique that can be used in a combined ultrasound energy and electrosurgical energy system.

[0034] FIG. 20 is a flowchart depicting an example of a thermal margin control technique that can be used in an electrosurgical system.

[0035] FIG. 21 is a flowchart depicting another example of a thermal margin control technique that can be used in an electrosurgical system.

[0036] FIG. 22A-22D is a flowchart depicting an example of an energy delivery technique that can use the amount of energy delivered to biological tissue, among other things, in its decision process.

[0037] FIG. 23 is a plot depicting an example of a relationship between a change in a measured value of an electrical parameter and a change in power.

[0038] FIG. 24 is a flowchart depicting another example of a power correction technique that can be used in a surgical system. DETAILED DESCRIPTION

[0039] Devices and related methods relate to the application of electrotreatment signals to biological tissue engaged by an electrosurgical instrument. Control of various electrical metrics of these electrotreatment signals, as well as particular electrosurgical techniques that perform such control, will be disclosed below. This specification is organized into sections entitled: i) Electrical power control of electrotreatment signals ( FIG. 1-4 ); ii) Predictive phase control of electrotreatment signals ( FIG. 5-6 ); iii) Correction of measured resistance of engaged biological tissue ( FIG. 7A-7B and FIG. 9 ); iv) Modification of initial impedance ( FIG. 9 ); v) Reduction of biological tissue adhesion to an electrosurgical instrument by pulsing electrical power of electrotreatment signals ( FIG. 10A-10D and FIG. 11 ); vi) Determination of presence of a conductive foreign object in biological tissue engaged by an electrosurgical instrument ( FIG. 12 and FIG. 13 ); vii) Short circuit error capture using a band between a trigger value and an escape value ( FIG. 14 ); viii) Open circuit check of impedance limit end point waveforms (FIG. 15 and FIG. 16 ); ix) Alternating power correction output in low-accuracy hardware systems ( FIG. 17 x) Reduced heat margin combined energy equipment ( FIG. 18 and FIG. 19 ); xi) is a graded impedance value used to control the thermal margin in systems with slow CPUs. FIG. 20 and FIG. 21 ); xii) Energy consumption monitoring and open circuit assessment ( FIG. 22A-22D (xiii) the dwell time between pulses; and (xiv) the incremental adjustment of control parameters as a function of the monitored variable. The techniques are described in these separate sections for illustrative purposes only. Each of these techniques may be used in combination with one or more of the other techniques described in this disclosure, unless expressly stated otherwise.

[0040] Electrical power control of electrotherapy signals ( FIG. 1-4 )

[0041] Electrosurgical closure or coagulation of biological tissue joined by electrosurgical instruments is an electrosurgical technique used in various medical procedures. Joined biological tissue can be electrosurgically closed by heating it in a controlled manner. In some medical procedures, the biological tissue being closed is a blood vessel. Heating the blood vessel causes the collagen found in the vessel wall to denature. This denatured collagen forms a gel-like substance that acts as a glue between the vessel walls. When forced together and held together while cooling, the opposing walls of the blood vessel form a closure.

[0042] Careful control of vessel heating is crucial, ensuring that neither too little nor too much energy is supplied. Excessive energy can lead to carbonization and / or burns of the vessel wall. Insufficient energy may result in poor vessel closure. One indicator of closure quality is the pressure differential the closed vessel can withstand without rupturing. Poor-quality closures can be compromised if the pressure applied to the closed vessel exceeds a certain threshold.

[0043] The rate at which energy is delivered to the blood vessels can also be carefully controlled to facilitate rapid execution of electrosurgical procedures. Rapid execution of electrosurgical procedures reduces the time and complexity of these processes. However, the heating rate should not be so rapid as to cause uncontrolled boiling of the fluids within the biological tissue. Uncontrolled boiling can cause rupture of the joined or nearby biological tissue and / or compromise the quality of the closure.

[0044] Heating of the joined biological tissue can be controlled by controlling the electrical power of the electrotherapy signal provided to and dissipated by the joined biological tissue. Such electrical power can be controlled according to a closure protocol. For example, the closure protocol can dictate a product of a voltage difference across the joined biological tissue and a current conducted by the joined biological tissue. Thus, the closure protocol is an electrical power protocol. In some examples, the electrotherapy signal can be reduced or terminated in response to satisfying a termination criterion. In some examples, the termination criterion is a current characteristic, such as a reduction in current conducted by the joined biological tissue. In some examples, the termination criterion is a resistance characteristic, such as an increase in electrical resistance of the joined biological tissue. Such an increase in electrical resistance beyond a predetermined incremental resistance value can be used as a termination criterion, for example, where the predetermined incremental resistance value is a difference between a measured electrical resistance (or impedance) and a lowest value of electrical resistance (or impedance) measured in the pulse. In some examples, the termination criterion is a time condition, for example, a predetermined or condition-based computed duration of time.

[0045] Electrical impedance is complex, and thus includes a real component (resistance) and an imaginary component (reactance). This document describes techniques using impedance or resistance. It will be understood that where complex impedance values are available, these values can be used in place of resistance values. Conversely, where complex impedance values are not available, resistance values can be used in place of, unless otherwise noted.

[0046] Furthermore, many of the following techniques describe delivering electrosurgical energy to biological tissue. Unless otherwise noted, each of these techniques can deliver the electrosurgical energy using controlled power or controlled voltage techniques. In implementations of controlled power, a control circuit can control delivery of the electrosurgical energy using a product of a voltage applied across the joined biological tissue and a current, for example, according to a plan or protocol. For example, the control circuit can control delivery of constant power or monotonically increasing power during a particular phase, such as a dry phase.

[0047] This document describes, among other things, one or more techniques for providing electrotreatment, which can be provided according to a treatment or other plan. The plan can include a recipe, prescription, protocol, method, etc. The plan can include one or more temporal aspects, e.g., a protocol, which can include, for example, timing of occurrence or recurrence (or prohibition or inhibition), frequency, type, relative combination (e.g., coagulation vs. cutting), etc. The plan can include electrotreatment waveform information, e.g., which can include pulse width, duty cycle, on-duration, off-duration, repetition rate, amplitude, phase, etc. The plan need not be static or a priori in nature, but can include one or more dynamic aspects, e.g., which can be modified or governed, e.g., using diagnostic, operational, or other information obtained during or between electrotreatment delivery instances, including in a closed loop or other feedback manner. One or more aspects of the plan can be customized, e.g., for a particular patient, a patient subpopulation (e.g., patients sharing one or more specified characteristics), or a patient population, e.g., which can be based on stored patient data, or by user input, e.g., which can be provided by a patient or caregiver. The plan can include one or more conditional aspects, e.g., which can include one or more branch conditions, e.g., which can be determined using patient characteristics, diagnostic measures, efficacy determinations, or operational characteristics of the device or its environment. Such branch conditions can be determined automatically by the device (e.g., without requiring user input), or can involve user input, e.g., which can be provided according to the plan before, during, or after one or more operational portions of the electrotreatment device. The plan can involve communicating with or using another device, e.g., receiving or providing one or any combination of inputs, outputs, or instructions, operational parameters, or measurement data. One or more aspects of the plan can be recorded or encoded onto a medium (e.g., a computer or other machine-readable medium, which can be tangible).

[0048] In implementations in which the controlled voltage is implemented, the control circuit can control the voltage of the delivered electrosurgical energy, e.g., according to a plan, protocol, or regimen. For example, the control circuit can control the delivery of a constant voltage or a monotonically increasing voltage during a particular phase, e.g., a dry phase.

[0049] FIG. 1 is a perspective view of an electrosurgical system providing electrotreatment to biological tissue of a surgical patient. In FIG. 1 The electrosurgical system 10 includes an electrosurgical generator 12 and forceps 14, which are shown engaging biological tissue 16. The electrosurgical generator 12 generates an electrotreatment signal, which is provided to the engaged biological tissue 16 via the forceps 14. While FIG. 1 While the forceps 14 are depicted engaging biological tissue and delivering an electrotreatment signal to the biological tissue 14, various types of electrosurgical instruments (such as those disclosed above) can be used for such purposes.

[0050] Various types of forceps can also be used to deliver the electrotherapy signal to the biological tissue 14. For example, the forceps 14 can be a medical forceps, a cutting forceps, or an electrosurgical forceps (e.g., a monopolar or bipolar forceps). In some examples, the forceps 14 can be used for medical related procedures, such as open and / or laparoscopic medical procedures, to manipulate, engage, grasp, cut, cauterize, seal, or otherwise affect a vessel, biological tissue, vein, artery, or other anatomical feature or object.

[0051] As shown in FIG. 1 , the forceps 14 includes a handpiece 18, a shaft assembly 20, a blade assembly 22, and a clamp assembly 24. In some examples, such as in the example shown in FIG. 1 , the forceps 14 is electrically connected to the electrosurgical generator 12, which generates the electrotherapy signal and provides the generated electrotherapy signal to the forceps 14. The forceps 14 then electrically delivers the electrotherapy signal to the clamp assembly 24 and / or a remote pad, which can be used for various electrosurgical techniques, such as cauterization, sealing, or other such electrosurgical techniques.

[0052] The handpiece 18 includes a handle 26, a clamp bar 28, a blade trigger 30, an electrotherapy actuation button 32, and a rotation wheel 34. The clamp assembly 24 includes a first jaw member 36 and a second jaw member 38. The shaft assembly 20 is connected to the handpiece 18 at a proximal end and connected to the clamp assembly 24 at a distal end. The shaft assembly 20 extends distally from the handpiece 18 to the clamp assembly 24 along a longitudinal direction 40.

[0053] The shaft assembly 20 acts to allow a portion of the forceps 14 (e.g., the clamp assembly 24 and a distal portion of the shaft assembly 20) to be inserted into a patient or other anatomical structure while the remainder of the forceps 14 (e.g., the handpiece 18 and the remaining proximal portion of the shaft assembly 20) is located outside of the patient or other anatomical structure. Although shown as being substantially straight in FIG. 1 , in other examples, the shaft assembly 20 can include one or more angles, curves, and / or arcs. The shaft assembly 20 can be a cylinder having a circular, elliptical, or other cross-sectional profile, or other elongated member extending from the handpiece 18 to the clamp assembly 24. In some examples, the shaft can be bendable, steerable, or deflectable.

[0054] In some examples, such as in the example shown in FIG. 1In the example, shaft assembly 20 may include an elongated hollow member (e.g., a tubular outer shaft) that surrounds blade assembly 22 and a mechanical linkage to couple blade assembly 22 to blade trigger 30. Typically, the shaft assembly can be any elongated member with sufficient stiffness to deliver force in the longitudinal direction 40. Shaft assembly 20 may also include conductive elements (e.g., wires, conductive outer shafts and / or conductive inner shafts, etc.) to provide electrical communication between handpiece 18 and clamping assembly 24, thereby delivering electrotherapy signals.

[0055] The gripping lever 28 of the handheld component 18, the knife trigger 30, the electrotherapy actuation button 32, and the rotating wheel 34 are all configured to cause various actuations of the shaft assembly 20, typically located at its distal end. For example, actuation of the gripping lever 28 is configured to control the operation of the gripping assembly 24 at the distal end of the shaft assembly 20. The gripping lever 28 is available in an open configuration position ( FIG. 1 A clamping actuator (shown) moves between a closed configuration position and a clamping position, wherein the clamping lever 28 moves proximally toward the handle 26. The movement of the clamping lever 28 proximally toward the handle 26 to the closed configuration position causes the clamping assembly 24 to change from an open configuration to a closed configuration. The distal movement of the clamping lever 28 (e.g., release of the clamping lever 28) to the open configuration position causes the clamping assembly 24 to change from a closed configuration to an open configuration.

[0056] By opening the construction ( FIG. 1 The transition between the open and closed configurations of the clamping assembly 24 is achieved by moving one or more of the first jaw member 36 and the second jaw member 38 between the open and closed configurations, in which the first jaw member 36 and the second jaw member 38 are spaced apart, and in the closed configuration, the gap between the first jaw member 36 and the second jaw member 38 is reduced or eliminated. Various electrosurgical instruments engage biological tissue 16 in various ways. In some electrosurgical instruments, for example in… FIG. 1 In the illustrated electrosurgical instrument, the first jaw member 36 and the second jaw member 38 may be opposed to each other. In the depicted example, the first jaw member 36 and the second jaw member 38 are configured to clamp biological tissue 16 therebetween in such a way that electrical communication is provided between the opposing jaw members 36 and 38 via the clamped biological tissue 16. Other electrosurgical instruments may engage biological tissue in other ways.

[0057] The mechanical linkage within the shaft assembly 20 can be configured to move one or more of the first jaw member 36 and the second jaw member 38 between an open and a closed configuration in response to actuation of the clamping lever 28. An example of a mechanism for moving the clamping assembly between the open and closed configurations can be found in U.S. Patent Publication No. 2017 / 0196579, entitled “FORCEPS JAW MECHANISM,” filed January 10, 2017, by Batchelor et al., the entire contents of which are incorporated herein by reference.

[0058] The actuation of the blade trigger 30 is configured to control the operation of the blade assembly 22 located at the distal end of the shaft assembly 20. The blade assembly 22 is configured to cut, remove, or otherwise affect biological tissue or other objects clamped between the first jaw member 36 and the second jaw member 38. The blade trigger 30 is capable of being in a retracted configuration position (…). FIG. 2 A blade actuator (shown) moves between an extended or retracted configuration position, wherein a blade trigger 30 moves proximally toward a handle 26 to cause the blade assembly 22 to cut biological tissue 16 clamped between a first jaw member 36 and a second jaw member 38. Moving the blade trigger 30 proximally toward the handle 26 to the extended configuration position causes the cutting blade of the blade assembly 22 to engage the biological tissue 16, thereby cutting the biological tissue 16. Distal movement of the blade trigger 30 (e.g., release of the blade trigger 30) causes the blade to retract from the clamped biological tissue 16. For example, a mechanical linkage within the shaft assembly 20 may be configured to engage and retract the blade from the engaged biological tissue 16.

[0059] The rotating wheel 34 is configured to control the rotational configuration of one or more of the blade assembly 22 and the clamping assembly 24 at the distal end of the shaft assembly 20, and / or to control the rotational configuration of the shaft assembly 20. Movement (e.g., rotation) of the rotating wheel 34 causes one or more of the shaft assembly 20, the blade assembly 22, and the clamping assembly 24 to rotate about an axis extending in the longitudinal direction 40. This rotational control facilitates the alignment of the clamping assembly and / or the blade assembly with the clamped biological tissue 16.

[0060] The electrotherapy actuation button 32 is configured to control the generation of an electrotherapy signal and / or the delivery of the electrotherapy signal to the engaged biological tissue 16. Actuation of the electrotherapy actuation button 32 causes an electrotherapy signal from, for example, the electrosurgical generator 12 to be applied to one or more of the first jaw member 36, the second jaw member 38, a remote pad (not shown), or other portion of the forceps 14 to cauterize, seal, or otherwise electrically affect a patient or other anatomical structure. One example of a handpiece that utilizes a clamp bar, a knife trigger, a rotary wheel, and an electrotherapy actuation button can be found in U.S. Patent No. 9,681,883 to Windgassen et al., entitled “FORCEPS WITH A ROTATION ASSEMBLY,” filed on June 20, 2017, the entirety of which is incorporated by reference herein.

[0061] FIG. 2 is a block diagram of an electrosurgical system for sealing biological tissue engaged by an electrosurgical instrument. In FIG. 1 , the electrosurgical system 10 includes an electrosurgical generator 12 and an electrosurgical instrument 14’. The electrosurgical instrument 14’ can be any electrosurgical instrument configured to engage biological tissue and deliver an electrotherapy signal to the biological tissue. The electrosurgical generator 12 is configured to generate an electrotherapy signal, such as a high frequency (AC) electrical signal, that the electrosurgical instrument 14’ delivers to the engaged biological tissue 16.

[0062] In some examples, the electrosurgical instrument 14’ is a forceps having a handpiece coupled to relatively opposable jaw members via a shaft assembly, such as the forceps 14 depicted in FIG. 2 . In other examples, the electrosurgical instrument 14’ is a conductive spatula, a conductive pad, or other electrosurgical device. These different types of electrosurgical instruments have a variety of ways of engaging biological tissue (e.g., clamping, contacting, encircling, penetrating, radiating, etc.).

[0063] The electrosurgical generator 12 includes an instrument interface 42, an electrical energy source 44, a measurement circuit 46, a control circuit 48, and a user interface 50. The instrument interface 42 can include, for example, signal drivers, buffers, amplifiers, ESD protection, and electrical connectors 52. The electrical connectors 52 are configured to electrically couple the electrosurgical instrument 14’ to the electrosurgical generator 12 to provide electrical communication between the electrosurgical generator 12 and the electrosurgical instrument 14’. Such electrical communication can be used to transfer operating electrical power and / or electrical signals therebetween. The electrosurgical instrument 14’ in turn can provide electrical communication between the electrical connectors 52 and the biological tissue engaged thereby.

[0064] The electrical energy source 44 is configured to generate an electrotreatment signal that is delivered to the engaged biological tissue via the electrically connected electrosurgical instrument 14'. The generated electrotreatment signal can be controlled to achieve the results desired for a particular electrosurgical procedure. In one example, for example, the electrotreatment signal is configured to resistively heat the engaged biological tissue to affect (e.g., seal) the engaged biological tissue in a surgical manner. Such control of the electrotreatment signal will be disclosed further below.

[0065] The measurement circuit 46 is configured to measure one or more electrical parameters of the engaged biological tissue by the connected electrosurgical instrument 14'. The measurement circuit 46 is in electrical communication with the connected electrosurgical instrument 14' when the electrosurgical generator 12 is electrically connected to the electrosurgical instrument 14' via the electrical connector 52. Various examples of the measurement circuit 46 are configured to measure various electrical parameters. For example, the measurement circuit 46 can be configured to measure a voltage difference delivered across the engaged biological tissue and / or a current conducted by the engaged biological tissue. In some examples, the measurement circuit 46 can be configured to measure a phase angle between the voltage difference delivered across the engaged biological tissue and the current conducted by the engaged biological tissue. In some examples, the measurement circuit 46 is configured to measure DC and / or AC electrical parameters of the engaged biological tissue.

[0066] The measured parameters, such as the measured voltage difference delivered across the engaged biological tissue and / or the current conducted by the engaged biological tissue, can be used to determine other electrical indicators. For example, the measurement of the voltage difference delivered across the engaged biological tissue and / or the current conducted by the engaged biological tissue and the phase angle between the voltage difference and the current can be used to determine the electrical resistance of the engaged biological tissue. The measurement of the voltage difference delivered across the engaged biological tissue and / or the current conducted by the engaged biological tissue and the phase angle between the voltage difference and the current can also be used to determine the complex impedance of the engaged biological tissue. The measurement of the voltage difference delivered across the engaged biological tissue and / or the current conducted by the engaged biological tissue and the phase angle between the voltage difference and the current can also be used to determine the apparent power (VA) and / or the real power (W) provided to the engaged biological tissue.

[0067] Such measurement of the electrical parameters can be used to control the electrotreatment signal during delivery to the engaged biological tissue. For example, the measurement of the voltage difference delivered across the engaged biological tissue and / or the measurement of the current conducted by the engaged biological tissue can be used to determine and / or control the real power provided to the engaged tissue. This determined real power can then be compared to an electrotreatment protocol. Such comparison can be used to generate an error signal. The measurement of the electrical parameters can also be used to determine phase control criteria for controlling the phases of the electrotreatment. The phase control criteria can include criteria for the start and termination of the phases, as well as criteria for control within the phases.

[0068] Control circuit 48 is configured to control the operation of electrical energy source 44 and / or measuring circuit 46. Control circuit 48 is electrically connected to electrical energy source 44 and measuring circuit 46. Control circuit 48 causes electrical energy source 44 to provide electrotherapy signals to biological tissue coupled by electrically connected electrosurgical instruments 14'. Control circuit 48 causes electrical energy source 44 to generate electrotherapy signals according to an electrotherapy protocol, thereby controlling the generated electrotherapy signals for specific electrosurgical procedures.

[0069] Various electrotherapy schemes can be used to achieve various types of electrotherapy. For example, in some examples, the actual power (W) of the electrotherapy signal supplied to the joined biological tissue is controlled according to an electrical power scheme. In other examples, the voltage difference (V) of the electrotherapy signal delivered across the joined biological tissue is controlled according to a voltage scheme. In other examples, the current (A) of the electrotherapy signal conducted by the joined biological tissue is controlled according to a current scheme. In still other examples, the apparent power (VA) of the electrotherapy signal supplied to the joined biological tissue can be controlled according to a voltage-ampere scheme.

[0070] For example, control circuit 48 can supply energy from electrical energy source 44 to the joined biological tissue, thereby controlling the product of the voltage difference across the joined biological tissue and the current conducted by the joined biological tissue according to the electrotherapy protocol. Control circuit 48 can generate an error signal using a comparison of the determined actual power with the electrotherapy protocol. This error signal can be used in a closed-loop feedback system including electrical energy source 44 to generate an electrotherapy signal according to the electrotherapy protocol.

[0071] like FIG. 2 As shown, the control circuit 48 includes a processor 54 and a memory 56. The control circuit 48 may include a timer and / or a clock. In some examples, the timer and / or clock is part of the processor 54. In other examples, the timer and / or clock is separate from the processor 54. In one example, the processor 54 is configured to implement functions and / or processing instructions for execution within the electrosurgical system 10. For example, the processor 54 may be able to receive and / or process instructions stored in the program memory 56P. The processor 54 can then execute the program instructions to cause the electrical energy source 44 to generate an electrotherapy signal according to a predetermined electrotherapy protocol. For example, the predetermined electrotherapy protocol can be retrieved from the data memory 56D. The processor 54 can compare electrical parameters measured by the measuring circuit 46 with the retrieved predetermined electrotherapy protocol. The processor 54 can send commands to the electrical energy source 44 and / or the measuring circuit 46. The processor 54 can also send or receive information from the user interface 50.

[0072] In various examples, it can be used FIG. 3A-3BThe electrosurgical generator 12 can be implemented with the elements shown in the middle or various other elements. For example, the processor 54 can include one or more of a microprocessor, a control circuit, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other equivalent discrete or integrated logic circuitry.

[0073] The memory 56 can be configured to store information within the electrosurgical system 10 during operation. In some examples, the memory 56 is described as a computer-readable storage medium. In some examples, a computer-readable storage medium can include a non-transitory medium. The term “non-transitory” can indicate that the storage medium is not implemented using waveforms, particles, or other propagating phenomena. In some examples, a non-transitory storage medium can store data that can change over time (e.g., RAM or cache). In some examples, the memory 56 is a temporary memory, which means that the primary purpose of the memory 56 is not long-term storage. In some examples, the memory 56 is described as a volatile memory, which means that the memory 56 does not retain stored contents when the power to the electrosurgical system 10 is turned off. Examples of volatile memory can include random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), and other forms of volatile memory. In some examples, the memory 56 is used to store program instructions for execution by the processor 54. In one example, the memory 56 is used by software or applications running on the electrosurgical system 10, such as a software program that implements electrical control of electrical therapy signals provided to biological tissue engaged by an electrosurgical instrument, to temporarily store information during program execution, for example, in a data memory 56D.

[0074] In some examples, the memory 56 can also include one or more computer- readable storage media. The memory 56 can be configured to store larger amounts of information than volatile memory. The memory 56 can further be configured for long-term storage of information. In some examples, the memory 56 includes non-volatile storage elements. Examples of such non-volatile storage elements can include magnetic hard discs, optical discs, floppy discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable (EEPROM) memories.

[0075] The user interface 50 can be used to deliver information between the electrosurgical system 10 and a user (e.g., a surgeon or technician). The user interface 50 can include a communication module. The user interface 50 can include various user input and output devices. For example, the user interface can include various displays, sound signal generators, as well as switches, buttons, touch screens, mice, keyboards, etc.

[0076] In one example, the user interface 50 utilizes the communication module to communicate with external devices via one or more networks, for example, one or more wireless or wired networks, or both. The communication module can include a network interface card, such as an Ethernet card, an optical transceiver, a radio frequency transceiver, or any other type of device that can send and receive information. Other examples of such network interfaces can include Bluetooth, 3G, 4G, and Wi-Fi radio computing devices and Universal Serial Bus (USB) devices.

[0077] FIG. 3A-3B is a flowchart of a non-limiting example of a method for generating an electrot herapy signal for sealing biological tissue joined by an electrosurgical instrument. FIG. 1-2 The method 100 shown in FIG. 1 can be used with an electrosurgical system such as the electrosurgical system 10 depicted in FIG. 2. FIG. 4 The electrosurgical system 10 depicted in FIG. 2 can be used with an electrosurgical system. Using the various techniques described below, the electrosurgical generator can control the energy delivery of a treatment signal provided to a biological tissue during a portion of a treatment phase according to incremental changes in energy delivery as a function of changes in measured electrical parameters of the biological tissue. In some examples, the control circuit can control the electrical power of a treatment signal provided to a biological tissue during a portion of a treatment phase, for example, by controlling the power during a phase in which the tissue is altered, according to a treatment plan.

[0078] For example, the control circuit can modify the power incrementally as a function of the current. In some examples, the function of the current is a function of a change in the current. The change in the current can be a change in the current over the course of a pulse, and thus can appear more like a current value. In some examples, the function of the current is a function of an instantaneous measured change in the current, and thus can appear more like a slope of the current function. The control circuit can modify the power based on either of the current or the instantaneous change in the current. In some examples, the function of the instantaneous measured change in the current is a linear function. In other examples, the control circuit can modify the power incrementally as a function of the resistance (e.g., when using a controlled voltage technique).

[0079] As FIG. 3A seen in

[0080] It should be noted that FIG. 3B and FIG. 4 as well as FIG. 3A are non-limiting specific examples for illustrative purposes.

[0081] In some examples, the method can switch from using a controlled power technique to using a controlled voltage technique. In a controlled voltage technique, the current can be limited, but the current is allowed to move freely according to the response impedance, which can enable variable power delivery. For example, the control circuit can deliver a pulse using a controlled power technique, and as the resistance increases, approaches a boiling state, or reaches a threshold, the system can switch to a controlled voltage technique. In this way, the system can initially utilize a controlled power technique to deliver energy more quickly, but as the system approaches boiling, the system can switch to a controlled voltage technique, which can be more sensitive. In some implementations using a controlled voltage technique, the system can control the electrical power of the treatment signal provided to the biological tissue during a portion of the treatment phase using a predetermined nominal voltage curve. In some examples, the predetermined nominal voltage curve can include two or more linear portions.

[0082] In FIG. 1-2 , the method 100 begins at step 102, where the electrosurgical system 10 (depicted in FIG. 2 ) is powered on. Then, at step 104, an interrogation phase begins, in which the control circuit 48 (depicted in FIG. 2 ) causes the generator 12 (depicted in FIG. 2The electrical energy source 44 (described in the diagram) provides an interrogation signal, such as an interrogation pulse, to the tissue of the joined biological organism. The power (W) of the provided interrogation signal is controlled according to the interrogation protocol. In some examples, the power level provided to the joined biological tissue during the interrogation phase may be very low, resulting in little or no tissue effect. This low power level can be provided to obtain measurements of the electrical properties of the joined biological tissue. Such measurements are sometimes obtained before the application of electrotherapy to obtain pre-electrotherapy measurements. In some examples, the interrogation protocol instructs the provision of constant electrical power during the interrogation phase. This protocol may be referred to as a constant power protocol. In some examples, the control circuit 48 terminates the interrogation phase after a predetermined duration.

[0083] At step 106, controller 48 causes ( FIG. 3B The measurement circuit 46 (described in the diagram) measures a first resistance of the joined biological tissue during the interrogation phase. The resistance measured during the first execution of step 106 is a reference resistance. Then, at step 108, the control circuit 48 compares the measured resistance with a previously measured minimum resistance (if any). At step 108, if the measured resistance is lower than the minimum resistance, the method proceeds to step 110, where the measured resistance is recorded as the new minimum value, and then the method proceeds to step 116 (at which point the first interval of the drying or baking phase begins). However, at step 108, if the measured resistance is greater than the minimum resistance, the method proceeds to step 112, where the control circuit 48 compares the measured resistance with the sum of the minimum resistance and a predetermined resistance increment. At step 112, if the measured resistance is less than the sum of the minimum resistance and the predetermined resistance increment, the method proceeds to step 114, where the measured resistance is ignored. However, at step 112, if the measured resistance is greater than the sum of the minimum resistance and the predetermined resistance increment, the method proceeds to... FIG. 4 Step 146 is shown.

[0084] At step 116, for example at the site of tissue alteration, a first interval of the drying or baking phase begins, wherein control circuitry 48, during the first drying interval of the drying phase, causes electrical energy 44 to deliver a first drying signal, such as a first drying pulse, to the joined biological tissue. The power (W) of the provided first drying signal is controlled according to a first drying scheme or plan, for example using a predetermined power curve with a linear slope. In some examples, the first drying scheme or plan is, for example, in… FIG. 3B The bottom curve shows a power scheme that monotonically increases between time t1 and t2.

[0085] Then, at step 118, the control circuit 48 compares the provided power to a first threshold, e.g., a first predetermined maximum power. If, at step 118, the provided power is greater than the first predetermined maximum power, the method proceeds to step 130 as shown in FIG. 13B, e.g., between times t2 and t3 as shown in the bottom plot of FIG. 13A, which depicts a second drying interval of the drying phase. In some examples including the second drying interval, the control circuit 48 can reduce the slope at block 130, e.g., as shown between times t2 and t3 in the bottom plot of FIG. 13A. In this way, the control circuit 48 can modify the energy delivery during the first pulse, e.g., the first drying pulse, in response to the first electrical parameter of the engaged biological tissue measured (e.g., intermittently) satisfying the first threshold. FIG. 4 FIG. 4 In some examples, the control circuit 48 can modify the energy delivery during the first pulse, e.g., the first drying pulse, in response to the first electrical parameter of the engaged biological tissue measured (e.g., intermittently) satisfying the first threshold. In some examples, the first threshold is a predetermined value. In some examples, the first threshold is a threshold that can change according to a pulse count. In some examples, the first threshold is a change in the first electrical parameter relative to an initial measurement of the first electrical parameter. In some examples, the first threshold is a change in the first electrical parameter relative to a maximum measurement of the first electrical parameter. FIG. 3B

[0086] The system can, for example, intermittently measure the first electrical parameter, e.g., current, and reduce or terminate the energy delivery during the treatment phase in response to the measured current of the engaged biological tissue satisfying a first threshold, e.g., a predetermined value. In some examples, the predetermined value is an absolute current threshold. In some examples, the predetermined value is a threshold that can change according to a pulse count. In some examples, the predetermined value is a change in the current relative to an initial current measurement. In some examples, the predetermined value is a change in the current relative to a maximum current measurement during a pulse of the treatment signal.

[0087] However, if, at step 118, the provided power is less than the first predetermined maximum power, the method proceeds to step 120, at which the control circuit 48 causes the measurement circuit 46 to measure the first electrical parameter, e.g., the impedance or current conducted by the engaged biological tissue.

[0088] At step 122, the control circuit 48 compares the measured current (or impedance), e.g., the first electrical parameter, for the pulse to a previously measured maximum current, e.g., a threshold, if any. If, at step 122, the measured current is greater than the maximum current, the method proceeds to step 124, at which the measured current is recorded as a new maximum, and then the method returns to step 116 to continue the first drying interval of the drying phase by modifying the energy delivery during the first pulse. However, if, at step 122, the measured current is less than the maximum current, the method proceeds to step 126, at which the control circuit 48 compares the measured current to a predetermined fraction of the maximum current.

[0089] ​​At step 126, if the measured current, such as a first measured current, is greater than a predetermined current threshold, such as a second measured current, the method returns to step 116 to continue the first drying interval of the drying phase. In some examples, the predetermined current threshold may be a ratio or fraction of the maximum current, such as 0.9, 0.8, 0.66, 0.5, and 0.4. In other words, control circuit 48 may continue drying signal or pulse in response to the ratio of the measured first current to the measured second current exceeding a predetermined factor indicating the absence of a liquid phase transition in the joined biological tissue. In other examples, the predetermined current threshold may be a difference rather than a ratio.

[0090] However, at step 126, if the measured current is less than a predetermined fraction of the maximum current, the method proceeds to step 128, at which point the first drying pulse of the first drying interval of the drying phase is terminated. The method then returns to step 104 to repeat the interrogation phase, after which the drying phase can be repeated or the closing phase can be initiated. In other words, the system can monitor the current during the treatment phase to determine when the treatment phase should end.

[0091] In some examples, and compared to determining at step 126 whether the measured current is less than a predetermined fraction of the maximum current, control circuit 48 may determine whether the measured current is less than a predetermined fraction (or offset) of the current value measured at a predetermined time interval after pulse initiation. For an impedance monitoring system, control circuit 48 may determine whether the measured impedance is greater than a predetermined fraction (or offset) of the resistance value measured at a predetermined time interval after pulse initiation.

[0092] exist( FIG. 3A At step 130 (as depicted), the second interval of the drying stage begins, during which the control circuit 48 causes the electrical energy 44 to provide a second drying signal, such as a second drying pulse, to the joined biological tissue during the second drying interval of the drying stage. It should be noted that, although... FIG. 3B and FIG. 4 The diagram illustrates a first and second drying interval for the drying phase, but the second drying interval may not be necessary. Instead, in some examples, the drying phase may terminate during the first drying interval. The power (W) of the provided second drying signal (e.g., a second drying pulse) is controlled according to a second drying scheme or plan (e.g., using a predetermined power curve). In controlled power (or controlled voltage or controlled current) techniques, the system can control the setting of the actuation energy level. A power (or voltage or current) constraint refers to an upper limit or threshold that the controlled current cannot cross, otherwise an error state would exist.

[0093] In other examples, the voltage (V) across the joined biological tissue is controlled during the second drying interval. In a controlled voltage technique, the system can control the setting of the actuation energy level. Voltage constraints refer to a controlled voltage that cannot cross an upper limit or threshold that otherwise presents an error state. In a controlled voltage implementation, the control circuit can monitor the voltage of the therapy signal and, when the threshold or upper limit is reached, the control circuit can maintain the voltage at the threshold. In some controlled voltage implementations, the voltage can be limited below the upper limit. In other controlled voltage implementations, the voltage can vary over time.

[0094] In the depicted example, the second drying interval uses a second drying scheme or plan that is a monotonically increasing power scheme. In some examples, for example, the second drying scheme or plan is a linearly increasing power scheme. Then, at step 132, the control circuit 48 compares the provided power to a second predetermined maximum power. If, at step 132, the provided power is greater than the second predetermined maximum power, the method proceeds to step 134, at which the control circuit 48 causes the power source 44 to provide power equal to the second predetermined maximum power (e.g., the power upper limit), and then the method 100 proceeds to step 136. However, if, at step 132, the provided power is less than the second predetermined maximum power, the method proceeds to step 136, at which the control circuit 48 causes the measurement circuit 46 to measure the current conducted by the joined biological tissue.

[0095] At step 138, the control circuit 48 compares the measured current to the previously measured maximum current. If, at step 138, the measured current is greater than the maximum current, the method proceeds to step 140, at which the measured current is recorded as a new maximum, and then the method returns to step 130 to continue the second drying interval of the drying phase. However, if, at step 138, the measured current is less than the maximum current, the method proceeds to step 142, at which the control circuit 48 compares the measured current to a predetermined fraction of the maximum current. If, at step 142, the measured current is greater than the predetermined ratio or fraction of the maximum current, the method returns to step 130 to continue the second drying interval of the drying phase. In other words, the control circuit 48 can decrease the drying signal or pulse in response to a ratio of the measured first current to the measured second current exceeding a predetermined factor that indicates a phase change in the liquid in the joined biological tissue. In other examples, the predetermined current threshold can be a difference. However, if, at step 142, the measured current is less than the predetermined fraction of the maximum current, the method can exit the second interval of the drying phase and return to step 104 to repeat the interrogation phase, after which the drying phase can be repeated or the sealing phase can be initiated. In other words, the system can monitor the current during the therapy phase to determine when the therapy phase should end.

[0096] At step 146, the sealing or solidification stage begins, at which point the control circuit 48 causes the electrical energy 44 to, for example, FIG. 3A During the closure phase between times t7 and t8, as shown in the bottom graph, a closure signal, such as a closure pulse (e.g., a second pulse), is provided to the joined biological tissue. The power (W) of the provided closure signal (e.g., the closure pulse) is controlled according to a closure scheme or plan. In some examples, the closure scheme or plan is a monotonically increasing power scheme. Then, at step 148, the control circuit 48 compares the provided power with a third predetermined maximum power. It should be noted that this is an example of a predetermined power curve with exactly a constant power domain. At step 148, if the provided power is greater than the third predetermined maximum power, the method proceeds to step 150, where the control circuit 48 causes the electrical energy source 44 to provide power equal to the third predetermined maximum power, and then method 100 proceeds to step 152 to measure, for example, intermittently, a second parameter of the joined biological tissue (e.g., tissue resistance). However, at step 148, if the provided power is less than the third predetermined maximum power, the method proceeds to step 152, where the control circuit 48 causes the measuring circuit 46 to measure the resistance of the joined biological tissue.

[0097] At step 154, control circuit 48 compares the measured resistance with a second threshold, such as a calculated termination resistance value. In some examples, the calculated termination resistance value is based on a reference resistance (e.g., a first resistance) measured at step 106. For example, the termination resistance value could be a predetermined coefficient multiplied by the measured reference resistance. In some examples, the termination resistance value could be the sum of a predetermined resistance increment and the measured reference resistance or the minimum resistance measured during this or a previous stage. In some examples, the target resistance is a predetermined incremental resistance, where the predetermined incremental resistance is the change in resistance relative to the minimum resistance measurement during the pulse of the treatment signal.

[0098] At step 154, if the measured resistance is less than the calculated termination resistance, the method returns to step 146 to continue the closing phase. However, at step 154, if the measured resistance is greater than the calculated termination resistance, the closing phase terminates, and the method ends. In other words, in response to, for example, intermittently measured impedance satisfying a second threshold (e.g., changing a predetermined incremental impedance value), the method can, for example, modify the energy delivery of the second pulse by reducing or terminating the energy delivery of the treatment phase (e.g., the closing phase).

[0099] In some non-restrictive examples, FIG. 3B and FIG. 4The methods shown in FIG. 1 1 can be implemented by a system such that the control circuit can monitor a first electrical parameter, e.g., current, in a first treatment phase, e.g., a dry phase, and reduce or terminate the first pulses based on the first electrical parameter, and monitor a second electrical parameter, e.g., impedance, in a second treatment phase, e.g., a sealing phase, and reduce or terminate the second pulses based on the second electrical parameter.

[0100] FIG. 4 is a graph depicting a non-limiting example of an electrotreatment regimen or plan for controlling the electrical power provided to biological tissue being sealed. In FIG. 4 In FIG. 2, the graph 200 has a horizontal axis 202, vertical axes 204A-204C, and functional relationships 206A-206C. The horizontal axis 202 indicates time (seconds). The horizontal axis has times to-t8, which represent the transition times between the interrogation, dry, and sealing phases disclosed in the discussion of the method 100 for generating an electrotreatment signal for treating biological tissue engaged by an electrosurgical instrument. These phases - the interrogation phase, the first dry phase, and the sealing phase - are also noted at different locations of the graph 200. It should be noted that, FIG. 4 The graph of FIG. 2 is for illustrative purposes only. FIG. 3A-3B The graph of FIG. 2 depicts an example of a response, and different tissues can have different reactions.

[0101] The vertical axis 204A indicates the electrical power (W) provided to biological tissue engaged by an electrosurgical instrument. The functional relationship 206A indicates a power / time relationship corresponding to an electrotreatment signal generated by the non-limiting example of the method 100 in FIG. 1 1, which is provided to the engaged biological tissue. FIG. 4 The graph of FIG. 2 depicts an example of a response, and different tissues can have different reactions.

[0102] In some examples, the functional relationship 206A can be a predetermined joule power curve that includes an interrogation phase, a dry phase, and a sealing phase. In FIG. 3AIn the specific non-limiting example shown, the drying phase depicts a first drying interval and a second drying interval. From time t0 to t1, the power / time relationship 206A indicates the interrogation phase. In some examples, the duration of the interrogation phase is as short as required to obtain a reference measurement of the bonded biological tissue. For example, the duration of the interrogation phase can be less than 1.0, 0.5, 0.25, or 0.1 seconds. As shown in graph 200, the interrogation phase is a constant power scheme or program with power P1 (W). From time t0 to t1, the current / time relationship 206B indicates a rapid current rise interrogation of the current conducted by the bonded biological tissue, followed by a current stabilization period, followed by a slight decrease. Because the power is controlled to be constant throughout the interrogation phase, the voltage applied across the bonded biological tissue is inversely proportional to the current / time relationship (in a multiplicative rather than additive sense). As the fluid temperature in the bonded biological tissue increases, the resistance of the tissue initially decreases. Since this is the first interrogation phase, the measured resistance is not less than the previously measured minimum resistance, and the method proceeds to the first drying phase.

[0103] From time t1 to t2, the power / time relationship 206A indicates the first interval of the drying stage. As shown in graph 200, the first drying interval of the drying stage is a power scheme or plan that monotonically increases from power P1 to P2 (W). From time t1 to t2, the current / time relationship 206B indicates the increase in current conducted by the bonded biological tissue throughout the first interval of the drying stage. Because the power is controlled throughout this first interval of the drying stage according to the drying scheme or plan, the product of the voltage applied across the bonded biological tissue and the current / time relationship should generate the power / time relationship 206A. Although not depicted, in some examples, the resistance / time relationship 206C may indicate that the resistance of the bonded biological tissue may initially decrease as the tissue warms up, but may subsequently increase as the tissue begins to dry during the first interval of the drying stage. This increased resistance may indicate the drying of the bonded biological tissue. Because the current does not decrease below a fraction of the previously measured maximum current before the power / time relationship 206A slopes to a predetermined threshold, the method proceeds to the second interval of the drying stage. If the current drops to a fraction below the previously measured maximum current during the first interval of the drying phase, then the second interval of the subsequent drying phase will be unnecessary (e.g., the second interval can be bypassed).

[0104] From time t2 to t3, the power / time relationship 206A indicates the second interval of the drying stage. As shown in graph 200, the second interval of the drying stage represents the electrical power scheme or plan that monotonically increases from power P2 to P3 (W). Using the information above... FIG. 3B and FIG. 2 The described technology, control circuit (e.g.) FIG. 3AThe control circuit 48) can control the energy delivery of the treatment signal provided to the biological tissue during a portion of the treatment phase as a function of the incremental change in energy delivery as a function of the measured change in the electrical parameter of the biological tissue. For example, the control circuit can incrementally modify the power as a function of the current. In some examples, the function of the current is a function of the instantaneous measured change in the current. In some examples, the function of the instantaneous measured change in the current is a linear function. In other examples, the control circuit can incrementally modify the power as a function of the resistance.

[0105] From time t2 to t3, the current / time relationship 206B indicates that the current conducted by the joined biological tissue increases at the beginning of the second interval of the drying phase, but reaches a peak at the end of the second drying phase and then decreases. It should be noted that the second interval of the drying phase can not be required. In some examples, the power can be controlled during the entire second interval of the drying phase such that the product of the voltage applied across the joined biological tissue and the current / time relationship can generate a particular power / time relationship 206A.

[0106] In some examples, the second interval of the drying phase is monotonically increasing, but the rate of increase is slower than the first interval of the drying phase. In other examples, the second interval of the drying phase is linearly increasing until the power provided equals a predetermined maximum level, after which the power provided remains constant. Because of the decrease in current, ΔΙ1 (e.g., the measured change in current (e.g., block 126 in FIG. 1)), the current is less than the predetermined fraction of the measured maximum current, the method returns to the interrogation phase, which is shown at time t3. In other words, the change in current, ΔΙ1, causes the method to enter the interrogation phase at time t3. It should be noted that in the non-limiting example shown, the change in current, ΔΙ1, that causes the method to enter the interrogation phase is after time t2. However, in other examples, the change in current, ΔΙ1, that causes the method to enter the interrogation phase can be after time t1 during the first interval of the drying phase, and the second interval of the drying phase can not be required. However, if the decrease in current, ΔΙ1, is less than the predetermined fraction of the measured maximum current, the method will remain in the drying phase. FIG. 4 FIG. 4 In the non-limiting example shown, the change in current, ΔΙ1, that causes the method to enter the interrogation phase is after time t2. However, in other examples, the change in current, ΔΙ1, that causes the method to enter the interrogation phase can be after time t1 during the first interval of the drying phase, and the second interval of the drying phase can not be required. However, if the decrease in current, ΔΙ1, is less than the predetermined fraction of the measured maximum current, the method will remain in the drying phase.

[0107] As seen in FIG. 1, in some examples, the pre-defined power curve 206A can include two or more linear portions, such as the linear portions shown between t1 and t2 and between t2 and t3. FIG. 3B

[0108] ​​From time t3 to t4, the power / time relationship 206A again depicts the interrogation phase. As shown in the graph 200, the interrogation phase is a constant power regime of power PI (W). Because the power is controlled to be constant throughout the interrogation phase, the voltage applied across the joined biological tissue is inversely proportional (in a multiplicative sense, not additive sense) to the current / time relationship. The resistance / time relationship 206C indicates that the resistance of the joined biological tissue decreases throughout the execution of the interrogation phase. The decrease in resistance can be a result of condensation of fluid in the tissue or migration of fluid into the tissue. Because the measured resistance is not greater than the sum of the reference resistance and the predetermined incremental resistance, the method again proceeds to the first drying phase.

[0109] From time t4 to t5, the power / time relationship 206A indicates another first interval of the drying phase. The power / time relationship from time t4 to t5 is similar to the power / time relationship 206A from time t1 to t2, and for the sake of brevity will not be described in detail.

[0110] From time t5 to t6, the power / time relationship 206A indicates another second interval of the drying phase. The power / time relationship from time t5 to t6 is similar to the power / time relationship 206A from time t2 to t3, and for the sake of brevity will not be described in detail. Because the power is controlled to be constant throughout this second interval of the drying phase, the voltage applied across the joined biological tissue should generate the power / time relationship 206A as a product of the current / time relationship. Because the decrease DI2 (e.g., the change in measured current (e.g., block 142 in FIG. 1)) is less than the predetermined fraction of the measured maximum current, the method returns to the interrogation phase. FIG. 5-6

[0111] From time t6 to t7, the power / time relationship 206A indicates another interrogation phase. The power / time relationship from time t6 to t7 is similar to the power / time relationship 206A from time t3 to t4, and for the sake of brevity will not be described in detail. Because the measured resistance is now greater than the sum of the reference resistance and the predetermined incremental resistance, the method proceeds to the sealing phase.

[0112] From time t7 to t8, the power / time relationship 206A indicates the sealing phase. As shown in the graph 200, the sealing phase is an electrical power regime or schedule that monotonically increases from power PI to power P3 (W). From time t7 to t8, the current / time relationship 206B indicates that the current conducted by the joined biological tissue increases throughout the sealing phase. The resistance / time relationship 206C indicates that the resistance of the joined biological tissue increases during the execution of the sealing phase. The increased resistance can be due to the drying of the joined biological tissue and thus the sealing of the joined biological tissue. Because the measured resistance is now greater than the predetermined termination resistance, the sealing phase terminates and the method ends. ​

[0113] Predictive phase control of electrosurgical signals FIG. 6

[0114] Electrosurgical procedures can have one or more electrosurgical phases. For example, an electrosurgical tissue sealing technique can have an interrogation phase, a desiccation phase, and / or a sealing phase. During each of these electrosurgical phases, a corresponding electrosurgical signal, such as an interrogation signal, a heating signal, a desiccation signal, a cauterization signal, etc., can be provided to biological tissue engaged by an electrosurgical instrument. The electrosurgical signals provided to the engaged biological tissue can be tailored to the technique being performed and / or to the particular tissue. Thus, each electrosurgical signal can be different for different procedures, different tissue types and quantities, and different electrosurgical phases. These differences in different electrosurgical signals can be obtained using different electrosurgical protocols and / or different phase control criteria. Differences between different electrosurgical protocols can stem from differences in controlled electrical parameters and / or differences in phase control criteria. As noted above, differences in controlled electrical parameters include the apparent power (VA), the real power (W), the voltage (V), and / or the current (A) of the electrosurgical signal. Phase control criteria include criteria for phase initiation and phase termination, as well as criteria for intra-phase control. Such phase control criteria include contemporaneous phase control criteria and predictive phase control criteria.

[0115] Contemporaneous phase control is performed by controlling the phase using real-time measurements. Predictive phase control is performed by using reference measurements taken at a reference time to generate future phase control criteria. For example, a measurement of tissue resistance taken prior to or during a desiccation phase can be used to generate a duration of continued desiccation phase. In some examples, the measurement of tissue resistance can be used to select one of a plurality of predetermined electrosurgical protocols. The selected electrosurgical protocol of the plurality of predetermined electrosurgical protocols can be used in a subsequent electrosurgical phase.

[0116] For example, a reference measurement of tissue resistance can be indicative of vessel size. Different electrosurgical protocols or plans and / or different phase control criteria can be used to heat vessels of different sizes. An appropriate electrosurgical protocol or plan tailored to the vessel size can enable safer sealing and reduce trauma to nearby tissue. To ensure proper sealing of an engaged vessel, an electrosurgical protocol can be tailored according to the size of the vessel to be sealed. The vessel size can be estimated based on a reference resistance of the engaged vessel measured. Vessel sealing can then be performed according to the electrosurgical protocol determined based on the reference resistance of the engaged vessel measured.

[0117] Techniques for predicting and delivering energy based on detected size of tissue, etc. are described below with respect to FIG. 2 Techniques for predicting and delivering energy based on detected size of tissue, etc. are described below with respect to FIG. 2 an electrosurgical generator, such as the FIG. 2 ​control circuit 48) and measurement circuit (e.g. FIG. 6 After the initial application of energy to the biological tissue by the measurement circuit 46), the impedance of the tissue at that time can be measured or calculated. The control circuit can then determine the type of tissue (e.g., small vessels or large vessels) in contact with the electrosurgical device, for example, between the jaws of the electrosurgical device, and then deliver energy for the detected type of tissue.

[0118] FIG. 6 is a flowchart of a method of biological vessel sealing that uses an electrical power regime that corresponds to the size of a biological vessel engaged by an electrosurgical instrument. FIG. 1 The method uses three treatment stages: Stage 1 is an interrogation stage, Stage 2 is a drying or desiccation stage, and Stage 3 is a vessel welding stage. In Stage 1, for example FIG. 6 The electrosurgical system of the electrosurgical system 10 can perform error checking and generate and deliver an interrogation signal to the engaged tissue according to an interrogation regime, for example. Although described in FIG. 7A-7B The control circuit can use controlled power techniques or controlled voltage techniques to deliver energy, although described in the context of controlled voltage. In controlled voltage techniques, the current can be limited but allowed to vary according to the response impedance, which can enable variable power delivery.

[0119] Using the techniques of the present disclosure, the method can begin a stage, for example, Stage 2, without the control circuit having determined what criteria will be used to terminate the stage. For example, as described in more detail below, the method begins Stage 2, and the control circuit and measurement circuit can determine an impedance measurement of the tissue. In response, the control circuit can determine whether to terminate Stage 2 based on a time measurement or based on iterative impedance measurements. In this way, the control circuit has two different criteria for how to terminate Stage 2, but without needing to enter Stage 2 having selected which of the two criteria to use.

[0120] At block 1900, Stage 1 begins, and at block 1901, the control circuit and measurement circuit can measure and / or calculate an initial impedance value Ro at time To. At block 1902, the control circuit can set a voltage ramp rate or slope for Stage 2. The voltage setting can be a constant voltage, an increasing voltage, or a decreasing voltage. Likewise, for implementations of controlled power, the control circuit can set a power ramp rate or slope for Stage 2. The power can be a constant power, an increasing power, or a decreasing power. The output of Stage 1 is the initial impedance value Ro.

[0121] At block 1904, stage 2 begins. At block 1906, after a set period of time, the control circuit and measurement circuit can measure or calculate a reference impedance Rl. The impedance of the tissue can change from the initial impedance RO to the impedance Rl. The impedance Rl is measured to determine whether stage 2 is an open loop stage (terminated based on a time criterion, e.g., by expiration of a timer) or a closed loop stage (terminated, e.g., based on an impedance criterion). For drier tissue, it can be desirable to run stage 2 as an open loop, while for wetter tissue, it can be desirable to run stage 2 as a closed loop.

[0122] At block 1908, the control circuit can determine whether the impedance Rl is greater than or equal to a threshold impedance value Ra. In some examples, the impedance Ra can be an absolute impedance. In other examples, the impedance Ra can be a delta value, e.g., a predetermined increase from the initial measured impedance RO. In some examples, the impedance Ra can be approximately 90 ohms.

[0123] In some examples, instead of or in addition to comparing the measured impedance Rl to the threshold impedance Ra, the control circuit can compare some other measured parameter to a threshold parameter. For example, the control circuit can compare the measured phase angle to a threshold phase angle. Examples of other parameters that can be used include, but are not limited to, energy delivered over a period of time, current consumption, tissue temperature, etc.

[0124] If the control circuit determines that the impedance Rl is greater than or equal to the impedance Ra (the “yes” branch of block 1908), the control circuit can run stage 2 as an open loop at block 1910 and continue to deliver power until the timer expires at time T2. At block 1912, stage 2 ends based on the time criterion, e.g., per the time interval.

[0125] However, if the control circuit determines that the impedance Rl is not greater than or equal to the impedance Ra (the “no” branch of block 1908), the control circuit can begin running stage 2 as a closed loop at block 1914. At block 1916, the control circuit can measure the impedance R2N at a set time interval. At block 1918, the control circuit can determine whether the current impedance measurement R2N is greater than or equal to an impedance threshold R2X.

[0126] If the control circuit determines that the impedance R2N is not greater than or equal to the impedance R2X (the “no” branch of block 1918), the method can continue to apply power and return to block 1914. At block 1916, the method can repeat the impedance measurement at the determined time interval and determine at block 1918 whether the new impedance measurement is greater than or equal to the threshold. In this way, the method can continue to apply power and iteratively compare the impedance measurement to the threshold impedance value.

[0127] If the control circuit determines that the impedance R2N (or any subsequent impedance measurement, if needed) is greater than or equal to the impedance R2X (“Yes” branch of block 1918), the control circuit can terminate phase 2 at block 1920 based on the impedance criteria (as opposed to the time criteria described above for open loop processing).

[0128] After the control circuit terminates phase 2, whether phase 2 was terminated based on time or impedance measurement, the control circuit can calculate and store the impedance measurement R3 at block 1922. Next, at block 1924, the control circuit can determine whether the current impedance measurement R3 is less than or equal to the impedance threshold value RX.

[0129] If the control circuit determines that the impedance R3 is greater than or equal to the impedance RX (“Yes” branch of block 1924), the tissue is small vessels, and the method can begin phase 3 at block 1926. At block 1928, the control circuit can run phase 3 as an open loop and continue to deliver electrical power until a timer expires at time T3. Phase 3 ends based on the time interval at block 1930.

[0130] However, if the control circuit determines that the impedance R3 is not greater than or equal to the impedance RX (“No” branch of block 1924), the tissue is large vessels, and the method can begin phase 3 at block 1932, and the control circuit can run phase 3 as a closed loop. At block 1934, the control circuit can measure the impedance R3N at a set time interval. At block 1936, the control circuit can determine whether the current impedance measurement R3N is greater than or equal to the impedance threshold value R3X.

[0131] If the control circuit determines that the impedance R3N is not greater than or equal to the impedance R3X (“No” branch of block 1936), at block 1938, the control circuit can determine whether a maximum time limit has been reached. If the control circuit determines that the maximum time limit has been reached (“Yes” branch of block 1938), the control circuit can terminate phase 3 at block 1940. In some examples, the time limit can be the time elapsed from the beginning of phase 1.

[0132] However, if the control circuit determines that the maximum time limit has not been reached (“No” branch of block 1938), the control circuit can continue to apply power and return to block 1934. The method can repeat the impedance measurement at block 1934 with the time interval, and determine whether the new impedance measurement is greater than or equal to the threshold impedance value R3X at block 1936. In this way, the method can continue to apply power and iteratively compare the impedance measurement to the threshold impedance value R3X.

[0133] If the control circuit determines that impedance R3N is greater than impedance R3X (the "Yes" branch of block 1936), then at block 1942 the control circuit can terminate stage 3 based on the impedance measurement (as opposed to the time criteria for the open loop processing of the stages described above).

[0134] Correction of measured resistance of joined biological tissue FIG. 9 and FIG. 7A )

[0135] The various electrical measurements described above can be used to determine an electrotherapy regimen and / or to determine stage control criteria. Thus, accurate measurements help to generate electrotherapy signals that will successfully achieve their therapeutic purpose. The temperature of an electrosurgical instrument, and of biological tissue joined by the electrosurgical instrument, affects electrical measurements of the joined biological tissue. This temperature / measurement relationship introduces uncertainty and / or complexity when using such electrical measurements to determine an electrotherapy regimen and / or stage control criteria. For example, a comparison of two electrical measurements of joined tissue taken at different temperatures of the joined tissue and / or the electrosurgical instrument can be complex.

[0136] Some example correct electrical measurements of joined tissue to account for the temperature of the electrosurgical instrument and / or the biological tissue. For example, a measured resistance of the biological tissue can be corrected based on an actual temperature measurement of the electrosurgical instrument. In some examples, the electrosurgical instrument will be equipped with a temperature sensor in thermal communication with the distal end that joins the biological tissue. In other examples, a measured resistance of the biological tissue can also be corrected based on a temperature of the tissue and / or the electrosurgical instrument predicted from various indirect measurements. For example, a measured tissue resistance can be corrected based on a time interval between a reference time and a measurement time during which electrical power has been delivered to the biological tissue. In some examples, a measured tissue resistance can be corrected based on a calculation of energy provided to the joined tissue prior to the electrical measurement.

[0137] FIG. 7A is a graph depicting measured tissue resistance as a function of jaw temperature of forceps. In FIG. 1 , graph 400 includes a horizontal axis 402, a vertical axis 404, and a resistance / temperature relationship 406. Horizontal axis 402 indicates jaw temperature of forceps. Vertical axis 404 indicates measured resistance of tissue clamped between opposable jaw members of forceps (e.g., forceps 14 depicted in FIG. 7B ). Resistance / temperature relationship 406 depicts measured values for a particular biological tissue clamped by opposable jaw members that have been heated to various temperatures. Resistance / temperature relationship 406 depicts a monotonically decreasing function in which measured resistance decreases as jaw temperature increases. This variation in measured resistance can be caused by many factors, including dependence of resistance on tissue temperature, tissue-liquid phase, jaw-tissue interface, jaw temperature, etc.

[0138] Such changes in the measured tissue resistance can introduce uncertainty and / or complexity in using such measured resistance to determine electrotherapy regimen and / or phase control criteria. Some resistance dependencies are undesirable because they do not indicate a therapeutic effect on biological tissue. Thus, compensating for these undesirable dependencies can improve the quality of such resistance measurements. Various methods of compensating electrical measurements of biological tissue can be performed to provide measurements that better indicate a therapeutic effect of an electrotherapy treatment.

[0139] FIG. 7B is a plot of jaw temperature versus time after termination of power application. In FIG. 1 , plot 410 includes a horizontal axis 412, a vertical axis 414, and a temperature-time relationship 416. Horizontal axis 412 indicates time after an electrotherapy signal has been provided to biological tissue. During this time after treatment, no power is delivered to the biological tissue. Vertical axis 414 indicates a measured temperature of an opposable jaw member of a jaw used to provide the electrotherapy signal to the tissue. Temperature-time relationship 416 depicts measured values of the jaw temperature at various times after treatment. Temperature-time relationship 416 is a monotonically decreasing function of time that asymptotically approaches room temperature. Such a temperature-time relationship can be characterized by a time constant that indicates a rate of decay.

[0140] The relationships depicted in plots 400 and 410 can be used to model jaw temperature as a function of power application and duration of power application after. For example, power dissipated by biological tissue engaged by an electrosurgical instrument can be used to predict a temperature of that biological tissue, as well as a temperature of an engagement of that electrosurgical instrument (e.g., opposable jaw members 36 and 38 depicted in FIG. 8 , can be determined theoretically (e.g., using a volume of tissue within an engagement of the opposable jaw members) and empirically (e.g., by characterizing the instrument). In some examples, a location of the engaged jaw members can be used to determine a volume of tissue within an engagement of the jaw members, for example. In some examples, a combination of theoretical and empirical characterization can be used to model a relationship between jaw temperature and power application. Jaw temperature versus time after treatment can similarly be characterized empirically and / or theoretically.

[0141] Furthermore, resistance dependencies that are undesirable because they do not indicate a therapeutic effect on biological tissue can be characterized empirically and / or theoretically. These different characterizations or models can then be combined to determine a compensated resistance value based on a measured resistance value. For example, a measurement of tissue resistance made during application of an electrotherapy signal to biological tissue can be compensated using a jaw temperature calculated based on an electrotherapy regimen. After application of an electrotherapy signal to biological tissue, a measurement of tissue resistance can be compensated using a duration of time after treatment.

[0142] FIG. 8 is a graph depicting the relationship of resistance compensation versus time after power application. In FIG. 8 , graph 420 includes a horizontal axis 422, a vertical axis 424, and an incremental resistance / time relationship 426. Horizontal axis 422 indicates time after an electrotreatment signal has been provided to biological tissue. During this time after treatment, no power is delivered to the biological tissue. Vertical axis 424 indicates the incremental resistance needed to compensate for the measured tissue resistance. In some examples, a multiplication factor can be used instead of an incremental resistance correction that is additive. Incremental resistance / time relationship 426 depicts the incremental resistance correction factor needed to compensate for the jaw temperature at various times after treatment. Incremental resistance / time relationship 426 is a monotonically decreasing function of time that asymptotically approaches zero.

[0143] In one example, the measured tissue resistance can be compensated for when the electrosurgical instrument is hotter than a predetermined threshold, but not when the electrosurgical instrument is cooler than the predetermined threshold. FIG. 8 Operation zones 428 and 430 are depicted, demarcating the two compensation mechanisms (e.g., hot and cold instrument mechanisms). Operation zone 428 spans from the time immediately after an electrotreatment signal is applied to biological tissue up to a predetermined time after the electrotreatment signal is applied to the biological tissue. During this hot instrument mechanism, the measured value of tissue resistance is compensated for by adding a predetermined incremental resistance value to the measured tissue resistance value. Operation zone 430 spans from the predetermined time after the electrotreatment signal is applied to the biological tissue up to the time the electrotreatment signal is removed from the biological tissue. During this cold instrument mechanism, no compensation of the measured value of tissue resistance is performed. FIG. 9 In the example depicted in, the time demarcating the transition from the hot instrument mechanism to the cold instrument mechanism is approximately 30 seconds after treatment. No compensation of the measured tissue resistance is performed under the cold instrument mechanism.

[0144] Modification of initial impedance FIG. 2

[0145] The control circuit of an electrosurgical generator (e.g., control circuit 48 of electrosurgical generator 12 of FIG. 1 ) can use a predictive algorithm to generate and deliver an electrotreatment signal to biological tissue between jaws of forceps 14 of, for example, forceps 14 of FIG. 9 engaged with the electrosurgical device. The predictive algorithm can include multiple stages. For example, stage 1 can use low power energy to initially access the vessel impedance and various energy delivery parameters. Based on the initial impedance determined in stage 1, the system can determine the size of the vessel to be sealed, set parameters to dry the vessel tissue in stage 2, and provide the appropriate energy level and duration to seal the vessel in stage 3.

[0146] However, accurately predicting vessel size can be challenging. For example, the initial vessel impedance that can be used to determine vessel size can be affected by the temperature of the jaws of the electrosurgical device. If a user attempts to close a second vessel immediately after closing a first vessel, the jaws can have a high temperature. The high temperature can affect the initial vessel impedance measurement.

[0147] The present inventors have recognized a need to reduce the temperature effects on initial impedance measurements and improve vessel size prediction. As described in more detail below, the present inventors have recognized that, in some examples, a temperature sensor coupled to the jaws can be used to determine the temperature of the jaws, and then a correction factor based on the temperature of the jaws can be used to modify the measured impedance. In other examples, the present inventors have recognized that a correction factor based on one or both of the time elapsed since a previous activation or the electrical characteristics of the previous activation can be used to modify the measured impedance. Using the modified impedance value, the electrosurgical system can more accurately predict the size of the vessel, which can be used to determine the settings of the electrosurgical generator.

[0148] FIG. 2 is a flowchart of a biological vessel closure method that can compensate for measured values of tissue impedance after power application. At block 2000, the control and measurement circuitry, e.g., the control circuitry 48 and the measurement circuitry 46 FIG. 1 , can measure an initial impedance Ro of biological tissue engaged to an electrosurgical device, e.g., the forceps 14 FIG. 10A-10D , in phase 1. At block 2002, the control and measurement circuitry can measure a temperature of the jaws of the electrosurgical device using a temperature sensor coupled to the jaws in phase 1.

[0149] At block 2004, using the measured impedance and the measured temperature of the jaws, the control circuitry can consult a stored data log or data set, e.g., a lookup table, and determine or select an adjusted or corrected impedance, i.e., a modification of the initial impedance Ro that takes into account the temperature of the jaws.

[0150] At block 2006, the control circuitry can use the determined adjusted impedance to determine a vessel size. For example, using an algorithm or another stored data set, the control circuitry can use the adjusted impedance to determine a vessel size.

[0151] Then, at block 2008, the control circuitry can use the determined vessel size to determine various electrical parameters that define an electrosurgical signal that the electrosurgical generator will generate and deliver to the biological tissue of the vessel. In some examples, the vessel size can be determined to be a small vessel or a large vessel, and there can be two electrosurgical signal settings that correspond to these two vessel sizes. In other examples, there can be a continuum of vessel sizes and electrosurgical settings that correspond to those vessel sizes.

[0152] At block 2010, the control circuit can use the determined signal setting to control delivery of the electrosurgical signal to the vessel to perform the seal, and the method can end at block 2012.

[0153] As shown in block 2014, some examples can store the time elapsed since the last activation, rather than using the jaw temperature. The longer the time elapsed, the more the jaw is cooled. In this way, the time elapsed since the last activation can be used as a proxy for the jaw temperature.

[0154] At block 2004, the control circuit can use the measured initial impedance Ro and the time elapsed since the last activation to determine an adjusted impedance. In some examples, the control circuit can compare the elapsed time to a time T, such as 20 seconds, and if the elapsed time is greater than or equal to T, the control circuit can use the initial impedance as the adjusted impedance. However, if the elapsed time is not greater than or equal to T, the control circuit can add a compensation value to the initial impedance Ro to determine the adjusted impedance. For example, the compensation value can be between about 80 ohms and 90 ohms. It should be noted that the compensation value and the time T can depend on the design of the jaw.

[0155] In some examples, rather than adding a compensation value to determine the adjusted impedance, the control circuit can query a stored data log or data set (e.g., a lookup table) and determine or select the adjusted impedance, i.e., a modification to the initial impedance Ro that takes into account the time elapsed since the last activation.

[0156] After the control circuit determines the adjusted impedance, the method can proceed to block 2006 and onwards (as described above) to determine the vessel size, signal setting, and perform the vessel seal.

[0157] At block 2014, in some examples, one or more electrical characteristics from the previous activation can be used in addition to the time elapsed since the last activation. For example, the control circuit can use the amount of energy or current from the previous activation to determine whether the previous activation generated a significant amount of heat on the jaw. If the activation was accidental or terminated quickly, little to no energy or current would have been delivered to the tissue, so the jaw would not have been heated significantly.

[0158] In some examples, the control circuit can determine the amount of energy from the previous activation by integrating the power curve from the previous activation. In other examples, the control circuit can determine the amount of energy from the previous activation by retrieving the applied time and average power delivered from a stored data set and multiplying the time by the average power delivered. Combining elapsed time information with energy or current information from a previous activation can improve the accuracy of the initial impedance Ro measurement and can improve the system's ability to determine vessel dimensions. Elapsed time, temperature, and electrical characteristics (e.g., energy and current) can be collectively referred to as "closure parameters."

[0159] In some examples that use both elapsed time and electrical characteristics, if the electrical characteristic (e.g., energy or current) is below a threshold, the control circuit can use the initial impedance Ro as the adjusted impedance. If the electrical characteristic is not below the threshold, the method can use the elapsed time to determine the adjusted impedance.

[0160] If the elapsed time is greater than a threshold, which would indicate that the jaws have sufficiently cooled, the control circuit can use the initial impedance Ro as the adjusted impedance. However, if the elapsed time is not greater than the threshold, the control circuit can add a compensation value of between about 80 ohms to 90 ohms to the initial impedance Ro to determine the adjusted impedance.

[0161] In some examples, rather than adding a compensation value to determine the adjusted impedance, the control circuit can query a stored data log or data set (e.g., a lookup table) and determine or select the adjusted impedance, i.e., a modification to the initial impedance Ro that takes into account the elapsed time and electrical characteristics (e.g., energy or current) since the last activation.

[0162] After the control circuit determines the adjusted impedance, the method can proceed to the operations of block 2006 and beyond (as described above) to determine vessel dimensions, signal settings, and perform vessel closure.

[0163] In the above examples, if the control system cannot definitively determine the elapsed time (and electrical characteristics such as energy or current, if used), the control circuit can determine an adjusted impedance corresponding to a large vessel. The default to a large vessel setting can enhance the safety of the vessel closure.

[0164] By using the above techniques, the control circuit can deliver an electrotreatment signal to biological tissue engaged with an electrosurgical device, measure an impedance of the engaged biological tissue, measure electrosurgical device closure parameters, and determine an adjusted impedance based on a relationship between the electrosurgical device closure parameters and the measured impedance.

[0165] By pulsing the electrical power of the electrotreatment signal to reduce the adhesion of biological tissue to the electrosurgical instrument FIG. 11 and FIG. 10A-10D )

[0166] FIG. 10A is a plot of an electrical parameter of an electrosurgical signal of an electrosurgical procedure having a pulsed, reduced-adhesion portion. In FIG. 10B the plot 500 includes a horizontal axis 502, a vertical axis 504, and a voltage / time relationship 506. The horizontal axis 502 indicates time. The vertical axis 504 indicates the voltage of an electrosurgical signal provided to tissue engaged by an electrosurgical instrument. The voltage / time relationship 506 depicts a measurement of the voltage differential taken at times indicated by the horizontal axis 502. The voltage differential is applied across tissue engaged by an electrosurgical instrument. As shown in the plot 500, the voltage / time relationship has four phases 508A-508D. The first phase 508A is an interrogation phase during which a modest voltage is provided to the engaged tissue to obtain an initial measurement of the tissue resistance.

[0167] The interrogation phase 508A is followed by a second phase 508B, which is a dry-out phase. During the dry-out phase 508B, the voltage differential provided across the engaged tissue is monotonically increasing. In the depicted example, the voltage differential provided across the engaged tissue is linearly increasing. In some examples, the dry-out phase 508B will have an initial slope that is greater than a final slope. In some examples, rather than controlling the voltage differential applied across the engaged tissue during the dry-out phase, another electrical parameter is controlled. For example, in some examples, the current conducted by the engaged tissue or the power provided to the engaged tissue (real or apparent) is controlled.

[0168] Each of the controlled parameters provides various advantages and disadvantages compared to the others. For example, controlling the voltage differential across the engaged tissue only requires measuring the voltage differential provided across the engaged tissue. However, as the tissue heats, the tissue resistance typically increases, causing the current flowing therethrough to decrease. Thus, when the power provided to the tissue decreases in response to the increase in tissue resistance, the rate of heating slows.

[0169] Controlling the current conducted by the engaged tissue only requires measuring the current conducted by the engaged tissue, which can be easily performed, for example, by measuring the voltage across a small series resistor. As described above, heating of the tissue typically causes an increase in the tissue resistance, causing the voltage differential across the tissue to increase. Thus, when the power provided to the tissue increases in response to the increase in tissue resistance, the rate of heating is accelerated.

[0170] However, controlling the actual power provided to the joining tissue requires measuring both the voltage difference across the joining tissue and the current conducted by the joining tissue. According to the electrotherapy regimen, both the voltage applied across the joining tissue and the current conducted by the joining tissue are adjusted as the tissue heats and the tissue resistance changes to maintain the power. The rate of heating is proportional to the power provided to the joining tissue, and thus controlled, e.g., the actual power (W) or the current (I).

[0171] The drying phase 508B is followed by a third phase 508C, which is a sealing phase. During the sealing phase 508C, the voltage difference provided across the joining tissue is constant. In some examples, the sealing phase 508C will not be constant. In some examples, rather than controlling the voltage difference applied across the joining tissue during the sealing phase, another electrical parameter is controlled.

[0172] The sealing phase 508C is followed by a fourth phase 508D, which is an adhesion reduction phase. During the adhesion reduction phase, the voltage is pulsed between a voltage maximum and a voltage minimum. Such pulsing alternately heats and allows cooling of the joining tissue. The adhesion reduction plan can have alternating electrical power minimums and maximums, where each of the electrical power minimums is below a predetermined threshold configured to allow the temperature of the clamped biological tissue to drop below a liquid / gas phase transition threshold to allow liquid to exist in the clamped biological tissue. In some examples, each of the electrical power minimums of the adhesion reduction plan is maintained for a first predetermined duration. In some examples, the first predetermined duration is greater than or equal to 5 milliseconds. In some examples, the first predetermined duration is greater than or equal to 10 milliseconds. In some examples, the first predetermined duration is greater than or equal to 50 milliseconds.

[0173] During the cooling portion of the pulsed waveform, liquid that has previously been driven out of the joining tissue can be returned to the joining tissue. In the depicted example, the pulsed waveform is periodic, where each cycle is identical to the previous cycle. In some examples, the pulsed waveform is not periodic. For example, each pulse maximum can be less than a previous pulse maximum.

[0174] The adhesion reduction phase 508D can be initiated in various ways. The adhesion reduction phase can begin after the appropriate sealing of the joining tissue has been completed. In some examples, a prediction phase control can be used to initiate or begin the adhesion reduction phase 508D. For example, the tissue resistance can be measured at a reference time during the interrogation phase 508A, the drying phase 508B, or the sealing phase 508C. The duration of the sealing phase can be predicted based on the tissue resistance measured at the reference time. The adhesion reduction phase 508D can be initiated in response to the predicted duration of the sealing phase having elapsed. In some examples, the tissue treatment can continue during the adhesion reduction phase.

[0175] In FIG. 10C the graph 510 includes a horizontal axis 512, a vertical axis 514, and a tissue resistance / time relationship 516. The horizontal axis 512 indicates time. The vertical axis 514 indicates the resistance of tissue engaged by the electrosurgical instrument. The tissue resistance / time relationship 516 depicts measurements of tissue resistance taken at times indicated by the horizontal axis 512. As shown in the graph 510, the tissue resistance is low during the interrogation phase 508A, increases during the drying phase 508B, and remains high throughout the occlusion phase 508C. During the reduced adhesion phase 508D, the tissue resistance alternates between low and high values. The low measurements of tissue resistance obtained during the minima of the pulse waveform indicate a return of liquid to the engaged tissue.

[0176] In FIG. 10D the graph 520 includes a horizontal axis 522, a vertical axis 524, and a current / time relationship 526. The horizontal axis 522 indicates time. The vertical axis 524 indicates the current conducted by the tissue engaged by the electrosurgical instrument. The current / time relationship 526 depicts measurements of current taken at times indicated by the horizontal axis 522. As shown in the graph 520, the current increases at the beginning of the drying phase 508B, but then decreases at the end of the drying phase 508B as the tissue resistance increases. The current then remains low throughout the occlusion phase 508C. During the reduced adhesion phase 508D, the current is substantially periodic with maximum values greater than the current values obtained during the occlusion phase 508C.

[0177] In FIG. 11 the graph 530 includes a horizontal axis 532, a vertical axis 534, and a power / time relationship 516. The horizontal axis 512 indicates time. The vertical axis 514 indicates the actual power of the tissue engaged by the electrosurgical instrument. The power / time relationship 516 depicts measurements of power provided to the engaged tissue taken at times indicated by the horizontal axis 532. As shown in the graph 530, the power increases at the beginning of the drying phase 508B, but then decreases at the end of the drying phase 508B as the tissue resistance increases. During the reduced adhesion phase 508D, the power is substantially periodic with maximum values greater than the power values obtained during the occlusion phase 508C. The power has a peak at the beginning of the maximum. These peaks in the power peak correspond to the current peaks that occur before liquid is expelled from the engaged tissue.

[0178] FIG. 11 is a flowchart of a method for reducing adhesion between biological tissue and an electrosurgical instrument. In FIG. 2 the method 540 begins at step 542 in which biological tissue is engaged by an electrosurgical instrument. Then, at step 544, a control circuit 48 FIG. 2 depicted in FIG. 4) causes an electrical energy source 44 (FIG. 2 interrogation signal to the engaged biological tissue during the interrogation phase. Then, at step 546, the control circuit 48 causes the measurement circuit 46 to measure a reference tissue resistance R FIG. 12 interrogation signal to the engaged biological tissue during the interrogation phase. Then, at step 546, the control circuit 48 causes the measurement circuit 46 to measure a reference tissue resistance R REF . Then, at step 548, a treatment duration T REF is determined based on the measured reference resistance R THERAPY .

[0179] At step 550, the control circuit 48 causes the energy source 44 to provide an electrotreatment signal to the engaged biological tissue during an electrotreatment phase. Then, at step 552, the elapsed treatment time T ELAPSED is compared to the determined treatment duration T THERAPY . At step 552, if the elapsed treatment time T ELAPSED is less than the determined treatment duration T THERAPY , the method returns to step 550, where the electrotreatment signal is provided to the engaged biological tissue. However, at step 552, if the elapsed treatment time T ELAPSED is greater than the determined treatment duration T THERAPY , the method 540 proceeds to step 554, where the control circuit 48 causes the energy source 44 to provide a pulsed adhesion reduction signal to the engaged biological tissue during an adhesion reduction phase. After the adhesion reduction phase, the method ends. The pulsed adhesion reduction signal can be determined according to an adhesion reduction protocol. The adhesion reduction protocol can be configured to reduce adhesion and, in some examples, to provide additional tissue treatment at the same time.

[0180] determining whether an electrically conductive foreign object is present in biological tissue engaged by an electrosurgical instrument FIG. 13 and FIG. 12 )

[0181] During various surgical procedures, artificial devices are implanted into a patient. For example, broken bones can be fixed with screws, bolts, washers, and other mechanical components. Staples can be used to maintain a desired arrangement of tissue that has been treated during a procedure. Pacemakers and other electronic devices can be implanted into a patient for various purposes. Many of these artificial devices are electrically conductive elements or contain electrically conductive elements. If an electrically conductive object is found in tissue engaged by an electrosurgical instrument, the electrically conductive object can interfere with the electrosurgical procedure.

[0182] Determining environmental conditions of an electrosurgical instrument, such as whether a conductive foreign object is present within the tissue to be joined prior to providing an electrotreatment signal to the tissue to be joined, can prevent undesirable tissue modification. Whether a conductive foreign object is present within the biological tissue being joined by an electrosurgical instrument can be determined based on the angle of impedance measurements of the biological tissue being joined. Thus, interrogating the angle of tissue impedance prior to an electrotreatment phase can prevent such undesirable tissue modification.

[0183] FIG. 12 is a graph depicting examples of impedance angle / time relationships of biological tissue with and without a metallic object in the biological tissue. In FIG. 2 , the graph 600 includes a horizontal axis 602, a vertical axis 604, and impedance angle / time relationships 606A-B. The horizontal axis 602 indicates time. The vertical axis 604 indicates the impedance angle of the biological tissue being joined by the electrosurgical instrument. The impedance angle / time relationships 606A-B depict measurements of impedance angle taken at times indicated by the horizontal axis 602 during an electrotreatment phase. The impedance angle of the biological tissue indicates the ratio of the reactance component of the tissue impedance to the resistance component of the tissue impedance. For example, an impedance angle of -90° indicates a purely capacitive tissue impedance, an impedance angle of +90° indicates a purely inductive tissue impedance, and an impedance angle of 0° indicates a purely resistive tissue impedance. In some examples, the measured reference impedance angle substantially equals the angle difference between the voltage measured across the biological tissue being joined by the measurement circuit and the conducted current.

[0184] The impedance angle / time relationship 606A corresponds to tissue in which no conductive foreign object is present. The impedance angle / time relationship 606B corresponds to tissue in which a conductive foreign object is present. As shown by the graph 600, the impedance angle / time relationships 606A and 606B indicate that the impedance angle changes during an initial or transient portion of the electrotreatment phase and then remains substantially constant during a final or steady-state portion of the electrotreatment phase. However, the steady-state values of the impedance angle for the impedance angle / time relationships 606A and 606B differ from one another. The impedance angle / time relationship 606A indicates a steady-state value of the impedance angle θ A that is less than the steady-state value of the impedance angle θ B indicated by the impedance angle / time relationship 606B.

[0185] Such a difference in the impedance angles θ A and θ B may be used to determine whether a conductive foreign object is present within the tissue being joined by the electrosurgical instrument. For example, a predetermined threshold impedance angle θ THRESH may be compared to the measured impedance angle of the biological tissue. If the measured steady-state impedance angle is less than the predetermined angle threshold θ THRESH (as in the impedance angle / time relationship 606A), then it can be determined that no conductive foreign object is present. However, if the measured steady-state impedance angle is greater than the predetermined angle threshold θTHRESH (As in impedance angle / time relationship 606B), then it can be determined that a conductive foreign object is present. In response, the control circuit, such as control circuit 48, can generate an error notification indicating that a conductive foreign object is present in the engaged biological tissue, and reduce or terminate delivery of the therapy signal. However, if a similar impedance is identified in the case where the steady state impedance angle is not greater than the predetermined threshold, the control circuit can continue to allow delivery of the therapy signal. Energy can be applied and increased until boiling is detected. Since the resistance is low in this state, the current will be at the high end of its typical value until boiling begins. FIG. 13 The control circuit of control circuit 48 can generate an error notification indicating that a conductive foreign object is present in the engaged biological tissue, and reduce or terminate delivery of the therapy signal. However, if a similar impedance is identified in the case where the steady state impedance angle is not greater than the predetermined threshold, the control circuit can continue to allow delivery of the therapy signal. Energy can be applied and increased until boiling is detected. Since the resistance is low in this state, the current will be at the high end of its typical value until boiling begins.

[0186] In some examples, the impedance or resistance of the engaged biological tissue is measured during the interrogation phase. If the magnitude of the measured impedance or resistance of the engaged biological tissue is less than a predetermined resistance value, the phase angle of the impedance is determined and compared to a predetermined threshold θ THRESH .

[0187] In some examples, if the measured steady state impedance angle is less than a predetermined angle threshold θ THRESH (As in impedance angle / time relationship 606A), then it can be determined that the circuit is open. In response, the control circuit can generate an error notification indicating that the circuit is open, and can reduce or terminate delivery of the therapy signal. In some examples, in response to the measured reference impedance angle being greater than a first angle (e.g., angle θΑ) and less than a second angle (e.g., angle θΒ), the control circuit can reduce the power level of the therapy signal. In some examples, the first angle can be about 70 degrees, which can be related to the device.

[0188] In this way, the system can compare the measured reference impedance angle to a predetermined angle threshold θ THRESH , and generate a response indicating an environmental condition of the instrument based on the comparison of the measured reference impedance angle to the angle threshold. The response can include a reduction in power and / or generation of a signal indicating the environmental condition. The response can include, for example, a notification signal indicating the condition to a user.

[0189] FIG. 13 is a flowchart of a method for determining whether a metallic object is present in biological tissue engaged by an electrosurgical instrument. In FIG. 2 , the method 620 begins at step 622, in which biological tissue is engaged by an electrosurgical instrument. Then, at step 624, the control circuit 48 (depicted in FIG. 2 ) causes the electrical energy source 44 (depicted in FIG. 2 ) to provide an electrical therapy signal to the engaged biological tissue during an electrical therapy phase. Then, at step 626, the elapsed therapy time T is compared to a predetermined time threshold T MEASUREA comparison is made. In step 626, if the elapsed treatment time T is less than the time threshold T... MEASURE If so, method 620 returns to step 624, and the electrotherapy protocol continues in step 624.

[0190] However, in step 626, if the elapsed treatment time T is greater than the time threshold T MEASURE Then method 620 proceeds to step 628, in which the control circuit 48 causes the measurement circuit 46 ( FIG. 14 The impedance angle θ of the conjoined biological tissues (described in the text) is measured. MEAS Then, in step 630, the measured impedance angle θ of the joined biological tissue is... MEAS With the predetermined reference angle θ REF A comparison is made. In step 630, if the measured impedance angle θ MEAS Greater than the predetermined reference angle θ REF If the error persists, the control circuit can generate an error notification, and method 620 proceeds to step 632, where treatment is terminated. For example, the control circuit can generate an error notification indicating the presence of a conductive foreign body in the joined biological tissue.

[0191] In some examples, a reference angle within a predetermined range (e.g., θ) MIN <θ MEAS <θ MAX This can be used to determine whether a conductive foreign body is engaged by an electrosurgical instrument. However, in step 630, if the measured impedance angle θ MEAS Less than the predetermined reference angle θ REF If so, method 620 proceeds to step 634, where treatment continues.

[0192] The predetermined impedance angle that defines the boundary between the presence and absence of a conductive foreign body can vary depending on the specific electrosurgical instrument, the electrical parameters of the specific electrosurgical signal, the type of biological tissue, etc. For example, the frequency of the electrosurgical signal can be related to the impedance angle that defines the presence / absence threshold.

[0193] Short-circuit error capture using the band between the trigger value and the escape value ( FIG. 2 )

[0194] As described above, electrosurgical generators (e.g., FIG. 2 The electrosurgical generator 12) can coagulate or close blood vessels or otherwise modify tissue by applying electrical energy via an electrotherapy signal. One problem with such energy application is that if the electrodes coupled to or integrated with the electrosurgical device are short-circuited, the electrical energy passes primarily through the short-circuited area rather than through the tissue surrounding it. In such cases, the tissue is largely unaffected by the applied electrical energy.

[0195] In one approach, insulating standoffs can be used to prevent the opposing electrodes from contacting each other and energy from being transferred through the contact points instead of through the tissue. However, conductive elements can be found in surgery that, when grasped by the electrosurgical instrument, can cause similar undesirable energy pathways. Examples of such elements include other surgical tools, metal clips, and staples.

[0196] In some systems, the electrosurgical generator can monitor for a particular (low) electrical impedance (collectively referred to as impedance), and can notify a user (e.g., a surgeon or technician) that such an undesirable energy pathway is currently occurring. If the electrosurgical generator determines that such a low electrical impedance exists, the electrosurgical generator can, for example, start a timer and alert the user of the problem via audible and / or visual notifications.

[0197] The electrosurgical generator can include a delay prior to any notification of a low impedance occurrence to prevent other occurrences of similar low impedances from falsely signaling that a "true short circuit" is occurring. Occurrences of other low impedances can occur due to, for example, added saline at the surgical site, highly conductive secretions (e.g., gall bladder bile), or thin, wet tissue (e.g., the omental web around the kidney), especially when used with large electrical surface area electrodes.

[0198] When such an environment is encountered, the prolonged application of energy can increase their electrical impedance by expelling the fluid or by converting the fluid to a gas through a phase change. This is typically accomplished, for example, for a set period of time, or the user is advised to dry the tip of the electrosurgical instrument and / or grasp the tissue in an alternative area. Thus, when the cause is tissue-derived and not a foreign body, it is preferable to obtain the expected modified tissue by continuing to apply energy during this initial short circuit condition.

[0199] During the application of energy in the tissue-derived initial short circuit condition, impedance fluctuations can occur in which the impedance increases enough to exceed the short circuit trigger value, but is still in a situation where the applied power cannot overcome the low impedance environment. In this case, instead of a fairly quick short circuit error (e.g., about 3 seconds), the energy can be applied until another time such as the absence of tissue effect or the maximum activation time error is met is met. However, this can lengthen the procedure, which can frustrate the user and create a negative user experience. Applying a filter to this situation can only do so much, so a more aggressive indicator of expelling the low impedance environment is more valuable.

[0200] The inventors have recognized the desirability of providing a system with an indication of whether a low impedance environmental short has been overcome or whether a small increase (followed by a decrease) in environmental impedance has been achieved. In some systems, these improvements can be particularly desirable, such as systems where the ability to measure and act on impedance feedback is less accurate. For example, a system can suffer from inaccuracy issues due to low voltage applied during low impedance situations, which can lead to greater difficulty in detecting phase angle shifts caused by the inherent inductive nature of the system as well as inductance created by the material between the device jaws.

[0201] The inventors have recognized that a two-boundary threshold can be used to provide an improved indication of whether a low impedance environmental short has been overcome or whether a small increase (followed by a decrease) in impedance has been achieved. As described in greater detail below, a system can monitor two impedance values: a trigger value and an escape value. The system can use a first impedance value ("trigger" value) to trigger a short, and the system can use a second impedance value ("escape" value) that is greater than the first impedance value to exit an error clock timing routine.

[0202] The inventors have recognized that a clinician can cause a fluid to locally boil, which can create bubbles with impedance. At this point, the impedance is significantly increased, which can push the impedance reading above the first impedance value, but not necessarily out of the shorted state. The inventors have recognized that the second impedance value can be important because it ensures that the system is drying out the tissue during the wait time. By using the two-boundary threshold technique of the present disclosure, the shorted state can be quickly communicated to the user, allowing the process to continue more quickly than using other techniques.

[0203] As described above, FIG. 1 An example of a surgical system that can be used to implement various aspects of the two-boundary threshold technique of the present disclosure is depicted. As FIG. 1 shown, FIG. 1 A surgical system can include an electrosurgical device such as forceps 14. Forceps 14 can include two jaws, such as first jaw member 36 and second jaw member 38. In some examples, one of the two jaws can be movable while the other jaw can be fixed. In other examples, both of the two jaws can be movable.

[0204] It should be noted that the two-boundary threshold technique of the present disclosure is not limited to electrosurgical devices that include jaws. Rather, devices such as shavers and snares can be used to implement the two-boundary threshold technique.

[0205] An electrosurgical device (e.g., forceps 14) can include two or more electrodes that are sized, shaped, and / or otherwise configured to deliver an electrotreatment signal to biological tissue (e.g.,FIG. 1 electrodes can be integral with the jaws (e.g., as in the first jaw member 36 and the second jaw member 38 of the electrosurgical device 10). In other examples, the electrodes can be coupled to the jaws. FIG. 2

[0206] An output circuit (e.g., including the power supply 44 of the electrosurgical device 10) can be configured to generate electrosurgical energy and deliver the electrosurgical energy to an output terminal (e.g., the instrument interface 42 of the electrosurgical device 10) for delivery to a patient. The output terminal can be configured to be coupled to an electrosurgical instrument (e.g., the forceps 14 of the electrosurgical device 10) and deliver the electrosurgical energy (e.g., high frequency such as RF energy) to biological tissue via an electrotherapy signal. FIG. 2 FIG. 1 FIG. 1 A control circuit of the surgical system (e.g., the control circuit 48 of the surgical system 20) can be coupled to the output circuit, and the control circuit can be configured to perform various aspects of the two boundary threshold technique. For example, a user such as a surgeon or clinician can initiate a continuous delivery of electrosurgical energy to biological tissue of a patient (e.g., tissue positioned between two jaws of an electrosurgical instrument). In some examples, a processor (e.g., the processor 54 of the control circuit 48) can control a measurement circuit (e.g., the measurement circuit 46 of the electrosurgical device 10) to measure a first impedance value of tissue in conductive communication with two electrodes of the electrosurgical instrument (e.g., the forceps 14 of the electrosurgical device 10). In some examples, the tissue can be positioned between the two electrodes of the electrosurgical instrument.

[0207] FIG. 2 FIG. 2 FIG. 1 FIG. 2

[0208] The processor can compare the measured first impedance value of the tissue to a first threshold value (e.g., a trigger value). In a non-limiting example for purposes of illustration, the trigger value can be about 5 ohms. When the measured first impedance value is less than or equal to the first threshold value, the processor (e.g., the processor 54 of the control circuit 48) can initiate a short circuit timer, for example, included in the processor. In a non-limiting example for purposes of illustration, the time limit of the timer can be about 3,000 milliseconds (ms) to about 6,000 ms. FIG. 2

[0209] The processor can control the measurement circuit to measure a second impedance value of the tissue positioned between the two electrodes of the electrosurgical instrument. The processor can then compare the second measured impedance value of the tissue to a second threshold value (e.g., an escape value), where the second threshold value (escape value) is greater than the first threshold value (trigger value). In a non-limiting example for purposes of illustration, the escape value can be about 10 ohms.

[0210] ​​​​​​​​​The trigger value and the escape value represent typical values, but are not absolute, and can depend on many factors, such as impedance within the device, exposed contact area, ability of the processor to measure impedance values from feedback, and cable length of the attached device, among other factors. The trigger value and the escape value can be tuned or adjusted for various systems. Additionally, the value of the timer limit can be tuned or adjusted, and can depend on the manufacturer’s understanding of the surgeon’s perception and willingness to wait to see if a short error will be indicated or if power application is preferred for a longer period of time.

[0211] When the second measured impedance value is less than the second threshold and the timer has not satisfied the time limit, the surgical system can continue to deliver the electrosurgical energy. However, when the second measured impedance value is less than the second threshold and the timer has satisfied the time limit, the control circuit can control the output circuit to reduce or terminate the delivery of the electrosurgical energy. In some examples, the control circuit can increase the power or current limit, or both, for a short period of time to continue to deliver energy to overcome a wet environment. In some examples, the surgical system can generate an indication to the user when the timer has satisfied the time limit. For example, a user interface (e.g., user interface 50 of the surgical system of FIG. 1) can generate one or both of an audible indication and a visual indication to the user that the delivery of the electrosurgical energy has been reduced or terminated. FIG. 1

[0212] The delivery of the energy can occur during an interrogation phase, in which the amount of energy delivered is low, but not zero. For example, during the interrogation phase, the energy delivered is not enough to affect the tissue.

[0213] In some examples, the control circuit can be configured to adjust at least one of the first threshold (trigger value), the second threshold (escape value), and the time limit based on at least one characteristic of the electrosurgical device. For example, the current density can affect the amount of power of the delivered electrot herapy signal, which can affect the amount of energy delivered by the system to the biological tissue. For example, the surface area of the electrode of the electrosurgical device can affect the current density. For example, for an electrosurgical device with a large surface area and a low power electrosurgical generator, there can not be enough current to quickly burn off the liquid in the tissue. Thus, it is desirable for the system to wait for a longer period of time before reducing or terminating the delivery of energy to the tissue. To this end, the control circuit can use the surface area of the electrode to adjust at least one of the first threshold (trigger value), the second threshold (escape value), and the time limit. For example, the control circuit can retrieve various one or more parameters of the electrosurgical device stored in a memory device, where the one or more parameters can include the surface area of the electrode associated with the electrosurgical device.

[0214] ​Additionally, the jaw force of the electrosurgical device can affect the current density. For example, a stronger jaw force can increase the amount of tissue in contact with the electrode, which can affect the boiling point of the tissue. As such, the control circuit can adjust at least one of the first threshold (trigger value), the second threshold (escape value), and the time limit of the electrosurgical device having a greater jaw force. The forceps 14 of the electrosurgical device (e.g. FIG. 2 may include a jaw force sensor configured to sense the jaw force, where the jaw force sensor is in communication with the control circuit (e.g. FIG. 14 control circuit 48).

[0215] In addition to the characteristics of the electrosurgical device, at least one of the first threshold (trigger value), the second threshold (escape value), and the time limit can be procedure dependent. For example, some procedures and / or tissues are more wet than others. For example, a liver procedure can involve a large amount of blood from the liver. In some procedures, the clinician can introduce a large amount of fluid to clean the tissue. As such, in some procedures, it can be desirable for the system to wait a longer period of time before terminating the delivery of energy to the tissue. To this end, in some examples, the control circuit can adjust at least one of the first threshold (trigger value), the second threshold (escape value), and the time limit, if needed, to allow the electrosurgical generator additional time to burn off excess fluid.

[0216] Alternatively or additionally, the characteristics of the electrosurgical device can be used to adjust the threshold or time limit. For example, the output current of the electrosurgical generator can affect the amount of power of the delivered electrotreatment signal, which can affect the amount of energy delivered to the biological tissue by the system. In some examples, the control circuit can adjust at least one of the first threshold (trigger value), the second threshold (escape value), and the time limit, if needed, based on the output current to allow the electrosurgical generator additional time to burn off excess fluid.

[0217] In some examples, the two boundary threshold technique of the present disclosure can be used during an initial tissue interrogation phase at the beginning of a procedure. In other examples, the technique can be used in the middle of the entire procedure (e.g., during a heating or drying phase).

[0218] For purposes of explanation, a non-limiting example of a system with and without an escape value will now be described. Initially, the clinician can press the activation button and attempt to deliver energy to the electrosurgical device, e.g., to the jaw. However, due to the high conductivity of the saline and blood irrigation on the electrosurgical device, the electrosurgical generator recognizes an impedance of 4 ohms and the short circuit timer starts.

[0219] For a system without an escape value, the electrosurgical generator can provide energy and at 1,000 ms of applied energy time, a bubble is created at, for example, the device jaws, by the short circuit timer, which can increase the impedance to 6 ohms. The bubble is transient, but because the impedance is now above the 5 ohm threshold, the short circuit timer is reset and the electrosurgical generator starts its 3,000 ms countdown again.

[0220] The transient bubble can occur multiple times, but it can be knocked off the jaws repeatedly, each time resetting the short circuit timer, until, for example, between about 12,000 ms to about 30,000 ms, a final alarm, such as the prolonged start-up time alarm, is triggered. The clinician can become frustrated with this experience and realize that they must draw some of the surrounding saline or grasp the tissue differently to achieve a good seal.

[0221] As described above, for a system without an escape value, the electrosurgical generator can provide energy and at 1,000 ms of applied energy time, a bubble is created at, for example, the device jaws, by the short circuit timer, which can increase the impedance to 6 ohms. However, because an escape value of, for example, 10 ohms is required to exit the short circuit loop, the short circuit timer continues. Another bubble is created, which can again increase the impedance to 6 ohms, which is again ignored by the short circuit timer because the impedance has not met the escape value or upper boundary requirement. At 3,000 ms, a short circuit alarm is presented to the clinician and the clinician now knows that the fluid must be removed or the tissue grasped differently. This reaction is faster due to the upper boundary “escape” value of 10 ohms, allowing the process to continue faster.

[0222] The two boundary threshold techniques described above can also be incorporated into other systems that utilize a short circuit trigger. For example, if the trigger value is met, the system can also interrogate the feedback to determine and interpret the phase angle at that point in time while waiting to see whether the short circuit timer or the escape value will be met first. If the phase angle is above a certain threshold, the system can determine that the frequency of the phase angle coupled with the low impedance indicates that a metal object is being inadvertently (or otherwise) grasped by the electrosurgical device. The system can continue to monitor the phase angle until either the upper escape value is met or the short circuit timer (e.g., 3,000 ms) is met.

[0223] FIG. 2 is a flowchart depicting an example of the two boundary techniques described above. At block 1000, a processor (e.g., processor 54 of control circuit 48 of system 10) FIG. 15 If the short circuit flag is not set (“NO” branch of block 1000), at decision block 1002, the processor can compare the measured impedance to a first impedance threshold (e.g., a 5 ohm threshold).

[0224] If the processor determines that the impedance is less than the first threshold (the "Yes" branch of block 1002), the processor resets the short circuit timer and sets the short circuit flag at block 1004, and can restart occlusion at block 1006. If the processor determines that the impedance is not less than the first threshold (the "No" branch of block 1002), the processor resets the short circuit timer and removes the short circuit flag at block 1008, and can restart occlusion at block 1006.

[0225] However, if the short circuit flag is set (the "Yes" branch of block 1000), at decision block 1010 the processor can compare the measured impedance to a second impedance threshold (e.g., a 7 ohm threshold). If the processor determines that the impedance is not less than the second threshold (the "No" branch of block 1010), the processor resets the short circuit timer and resets the short circuit flag at block 1008, and can restart occlusion at block 1006. If the processor determines that the impedance is less than the second threshold (the "Yes" branch of block 1010), at block 1012 the processor can compare the short circuit timer to a timer limit (e.g., 3000 ms).

[0226] If the processor determines that the short circuit timer is greater than the timer limit (the "Yes" branch of block 1012), the processor can generate a short circuit alert (e.g., an audible and / or visual notification) at block 1014 to notify the user. If the processor determines that the short circuit timer is not greater than the timer limit (the "No" branch of block 1012), occlusion can be restarted at block 1006.

[0227] In this way, if the impedance is less than a first impedance threshold (e.g., 5 ohms) for at least a duration defined by the short circuit timer (e.g., 3000 ms), a short circuit alert can be generated and the electrotherapy signal will be reduced or terminated. There can be a hysteresis between the first impedance threshold and a second impedance threshold (e.g., 5 ohms and 7 ohms) such that the timer will be started (e.g., with a 3000 ms timer limit) when the impedance drops below the first threshold (e.g., 5 ohms) and reset when the measured impedance rises above the second threshold (e.g., 7 ohms).

[0228] Open circuit check for impedance limit end point waveforms FIG. 16 and FIG. 2

[0229] RF vessel sealing devices typically use a fixed maximum impedance value such as to indicate that the tissue is being properly affected or use an impedance delta to detect when the tissue is being properly affected. Impedance can also be used to identify whether the instrument jaw has opened during activation. For example, the system can attempt to detect an impedance above a setpoint to identify an "open circuit" which indicates that the jaw is open. ​

[0230] However, in some cases, opening the jaws during activation can cause a "false positive" in which the generator issues a signal that the closure is good, but in fact, the user has just opened the device jaws. For example, with a system monitoring a "good closure" endpoint (e.g., 350 ohms) and an "open circuit" error value (e.g., 2000 ohms), the system can react to this false positive during activation. The user controls the energy application to the tissue, and the system can monitor both the endpoint and the open circuit. In a correct activation, the energy application can initially decrease the impedance, e.g., from 30 ohms to 15 ohms, and then can increase the impedance of the tissue as the energy desiccates the tissue. The energy increase can meet the 350 ohm endpoint value, and the generator can stop applying power and send a signal to the user indicating that the closure is complete.

[0231] In another example, the user controls the energy application to the tissue, and the energy application can initially decrease the impedance of the tissue, e.g., from 30 ohms to 15 ohms, and then the impedance begins to rise. During this rise, the user slowly (or quickly) opens the jaws. The impedance value can quickly increase, first passing the required 350 ohm boundary, at which time the system turns off the power and reports a good closure. Because the energy is turned off (and if the situation of greater than 350 ohm tissue occurs, continuing to apply energy would create the situation of "adhesion of the tissue to the jaws") and the impedance will not reach the 2000 ohm "open circuit" error value, the system falsely reports a good closure.

[0232] The present inventors have recognized the need for an open circuit check that begins with starting a timer when the user initiates the continuous delivery of electrical surgical energy to biological tissue. When the timer reaches a timer limit (or "timeout"), the system can determine the impedance value and determine whether the impedance value represents an open circuit. If the impedance value does represent an open circuit, the system can reduce or terminate the delivery of energy, and if the impedance value does not represent an open circuit, the system can allow the energy application to continue until the impedance meets an endpoint value.

[0233] Using the proposed timer technique, an electrosurgical generator (e.g., FIG. 1 electrosurgical generator 12 of the GEN300®) can apply energy to the system and biological tissue in contact between the electrosurgical device (e.g., FIG. 2 jaws of forceps 14 of the GEN300®). When the control circuit has determined that the tissue is ready to be driven to a final impedance endpoint value or an impedance delta value, the processor (e.g., FIG. 2 processor 54 of control circuit 48 of the GEN300®) system can set a timer, e.g., 50 ms to 100 ms.

[0234] When the timer "times out," the measurement circuit (e.g., FIG. 2The measurement circuit 46) measures the impedance value. The processor can determine whether the measured impedance represents an open circuit and energy delivery should be reduced or terminated, or whether the measured impedance is below the open circuit value and energy delivery can continue until the impedance meets the required endpoint value. By using these techniques, there is a minimum time period in which neither the endpoint value nor the open circuit value can be achieved, but depending on the impedance measured at the end of this time period, the processor can decide whether to flag an "open circuit" error and reduce or terminate the delivery of energy or continue the delivery of energy to the full occlusion cycle endpoint impedance value.

[0235] Several possible scenarios that can occur using the open circuit check technique will now be described. In a first scenario, the user applies energy to tissue, for example between the jaws of an electrosurgical device, and the impedance of the tissue decreases and then increases. The processor can identify that the tissue is being properly affected and can then start a timer. After a time limit (e.g. 50ms), the impedance is below the "open circuit" value (e.g. 2000 ohms absolute or impedance delta value), but also below the target tissue endpoint value (or impedance delta value). As such, the processor continues to control the application of power until the target endpoint value is reached. The processor terminates the application of power and indicates to the user that a good occlusion has been achieved.

[0236] In some examples, the rate of change of impedance can be the trigger variable. For example, if the rate of change of impedance exceeds a pre-set value, the generator can report an open circuit and then modify the energy output (or terminate or significantly reduce).

[0237] In a second scenario, the user applies energy to tissue, for example between the jaws of an electrosurgical device, and the impedance of the tissue decreases and then increases. The processor can identify that the tissue is being properly affected and can start a timer. After a time limit (e.g. 50ms), the impedance is below the "open circuit" value (e.g. 2000 ohms absolute or impedance delta value), but the tissue is at or above the tissue endpoint value (e.g. 350 ohms). The processor terminates the application of power and indicates to the user that a good occlusion has been achieved.

[0238] In a third scenario, the user applies energy to tissue, for example between the jaws of an electrosurgical device, and the impedance of the tissue decreases and then increases.

[0239] The processor can identify that the tissue is being properly affected and can then start a timer. The user prematurely releases the tissue, for example by opening the device jaws, and the impedance rapidly increases through the endpoint value and then through the open circuit value (e.g. 2000 ohms absolute or impedance delta value). For example, after 50ms, the processor can determine that the impedance exceeds the open circuit value, terminate the application of power, and indicate to the user an incomplete occlusion "open circuit" error message.

[0240] The duration of the timer can be important to successfully correctly identify an open circuit and a good seal. If the duration is too long, for example when a user is attempting to affect thin fascial material on the internal wall of the pelvic cavity, a small amount of tissue can quickly reach impedance values greater than the open circuit value. Although such tissue is typically very conductive initially, the fluid contents can quickly boil, and for example a portion of such thin material within the device jaws causes a rapidly increasing impedance. For example, if the timer duration is 200 ms, a good seal or tissue modification of thin fascial material on the internal wall of the pelvic cavity will result in a false message, rather than the appropriate good seal normal state.

[0241] If the timer is too short, false positives can occur. For example, if the timer is set to 10 ms, the following can occur. The user applies energy to the tissue, and the impedance decreases, and then increases. When the impedance increases, the processor determines that the tissue is ready to be driven to the endpoint and starts the timer. If the jaws are opened slowly, the impedance slope of the jaws does not meet the open circuit value within 10 ms, and thus the control circuit continues to apply energy. For example, as the impedance continues towards the open circuit value of 2000 ohms, the impedance value passes the endpoint value of 350 ohms and stops applying power, thus incorrectly giving a good seal normal state at the end.

[0242] The values of the timer, the endpoint impedance, and the open circuit impedance can depend on many factors, for example the following factors (alone or in combination): 1) the amount of power applied to the tissue at the time (and can be the set power or power that is considered and the timer and / or impedance values are adjusted accordingly); 2) the target tissue (previous power feedback can provide an indication of the type of tissue between the jaws, and the likely or expected impedance slope is predicted, and the timer and / or impedance values are adjusted accordingly); and 3) the surface area of the electrodes and / or the force applied by the electrode jaws in their fully closed position.

[0243] Using the open circuit check technique described in more detail below, when ready to drive the tissue to the (sealed) endpoint value, the electrosurgical system (e.g., system 10 in FIG. 15 The system can set a timer, for example 50 ms to 100 ms, when ready to drive the tissue to the (sealed) endpoint value. When the timer reaches the limit and "times out", the system can measure the impedance (or rate of change of impedance over time) and determine whether the value represents an open circuit condition or whether to continue to apply energy until the impedance meets the endpoint value indicating a good seal. In this way, there is a minimum period of time in which neither the endpoint value nor the open circuit value is achieved. However, depending on the impedance determined at the end of the timer, the system can determine whether to proceed to the full seal cycle endpoint value or indicate that there is an open circuit.

[0244] FIG. 1This is a flowchart depicting an example of the above-mentioned open-circuit examination technique that can be used in a surgical system. For example... FIG. 1 As shown, FIG. 1 The surgical system may include an electrosurgical device such as forceps 14. Forceps 14 may include two jaws, such as a first jaw member 36 and a second jaw member 38. In some examples, one of the two jaws may be movable, while the other jaw may be fixed. In other examples, both jaws may be movable.

[0245] It should be noted that the open-circuit inspection techniques described in this disclosure are not limited to electrosurgical devices including clamps. Rather, open-circuit techniques can be achieved using devices such as scrapers and snares.

[0246] Electrosurgical devices (e.g., forceps 14) may include two or more electrodes, which are sized, shaped, and / or otherwise configured to deliver electrotherapy signals to biological tissue (e.g., FIG. 1 (Organization 16). In some examples, the electrodes can be coupled with jaws (e.g., as shown in the image). FIG. 2 The first jaw member 36 and the second jaw member 38 are integrated. In other examples, the electrodes may be coupled to the jaws.

[0247] Output circuit (e.g., including) FIG. 2 The power supply 44) can be configured to generate electrosurgical energy and deliver the electrosurgical energy to the output terminal (e.g., FIG. 1 The instrument interface 42) is used for delivery to the patient. The output terminal can be configured to couple to an electrosurgical device (e.g., FIG. 1 The forceps 14), and deliver electrosurgical energy (e.g., high frequency such as RF energy) to the biological tissue via electrotherapy signals. The control circuitry of the surgical system (e.g., FIG. 15 The control circuit 48) of the surgical system can be coupled to the output circuit, and the control circuit can be configured to perform various aspects of the open-circuit inspection technique.

[0248] Now refer to FIG. 2 At box 1100, for example, when a user, such as a surgeon or clinician, initiates the continuous delivery of electrosurgical energy to biological tissue positioned between two electrodes of an electrosurgical device, the control circuitry may activate a timer. In some examples, the timer may be included in the processor (e.g., FIG. 2 In the processor 54). In some examples, the control circuitry can set a timer when it has determined that the tissue is ready to be driven to the final impedance endpoint value (or impedance increment value). In some examples, the processor (e.g., FIG. 2 The processor 54 of the control circuit 48 can control the measurement circuit (e.g., FIG. 1measurement circuit 46) to measure an impedance value of tissue positioned between two electrodes of an electrosurgical device (e.g., FIG. 2 a forceps 14).

[0249] At block 1102, the processor can determine whether the timer is greater than a timer limit (e.g., 50 ms to 100 ms). If the timer has not exceeded the time limit (“No” branch of block 1102), the system can continue delivery of electrosurgical energy at block 1104. If the timer has satisfied the time limit (“Yes” branch of block 1102), the processor can compare the representation of the measured impedance to a first threshold (endpoint value) (e.g., 250 ohms to 350 ohms) at block 1106. The first threshold can be stored in a memory (e.g., FIG. 2 memory 56) in the surgical system.

[0250] At block 1108, if the processor determines that the representation of the measured impedance is less than the first threshold (“Yes” branch of block 1108) (endpoint value), the processor can continue delivery of electrosurgical energy. If the processor determines that the representation of the measured impedance is not less than the first threshold (“No” branch of block 1108), the processor can compare the representation of the measured impedance to a second threshold (open circuit value) (e.g., 2000 ohms) at block 1110. The second threshold can be stored in a memory (e.g., FIG. 2 memory 56) in the surgical system.

[0251] If the processor determines that the representation of the measured impedance is less than the second threshold (“Yes” branch of block 1110), the processor can reduce or terminate delivery of electrosurgical energy at block 1112. Here, the measured impedance is greater than the first threshold (endpoint value) and less than the second threshold (open circuit value), which indicates that a good seal has been achieved. In some examples, the control circuit can generate a notification to the user to indicate a good seal.

[0252] If the processor determines that the representation of the measured impedance is not less than the second threshold (“No” branch of block 1110), the processor can reduce or terminate delivery of electrosurgical energy at block 1114. Here, the measured impedance is greater than the first threshold (endpoint value) and also equal to or greater than the second threshold (open circuit value), which indicates that an open circuit exists. In some examples, the surgical system can generate an indication to the user to indicate an open circuit. For example, a user interface (e.g., FIG. 2 user interface 50) of the surgical system can generate one or both of an audible indication and a visual indication to the user to indicate that delivery of electrosurgical energy has been reduced or terminated and that an open circuit was detected.

[0253] As described above, in some examples, the processor (e.g., FIG. 2the processor 54 of the control circuit 48) can control the measurement circuit (e.g., FIG. 5 the measurement circuit 46 of the control circuit 48) to measure an impedance value of the tissue, and the processor can determine whether a representation of the measured impedance exceeds a threshold value. In some examples, the representation of the impedance includes a value of the impedance, such as an absolute value of the impedance. In other examples, the representation of the impedance includes a change in the value of the impedance (or "delta") with respect to time, such as a first derivative of the impedance with respect to time.

[0254] FIG. 16 is a flowchart depicting another example of the open circuit check technique described above that can be used in a surgical system. In the method 300, at block 302, the control circuit can start a timer at the beginning of phase 3. At block 304, the control circuit can apply electrosurgical energy to biological tissue positioned between two electrodes of an electrosurgical device. At block 306, the control circuit can determine whether an endpoint is met. If the control circuit determines that the endpoint has not been met (the "No" branch of block 306), the control circuit can return to block 304 and continue to apply electrosurgical energy to the biological tissue. However, if the control circuit determines that the endpoint has been met (the "Yes" branch of block 306), the method proceeds to block 308.

[0255] At block 308, the control circuit can determine whether the elapsed time is less than or equal to a timer limit. If the control circuit determines that the elapsed time is less than or equal to the timer limit (the "Yes" branch of block 308), the control circuit can reduce the delivery of electrosurgical energy and indicate an open circuit at block 310. If the control circuit determines that the elapsed time is not less than or equal to the timer limit (the "No" branch of block 308), the control circuit can reduce the delivery of electrosurgical energy and indicate that a good seal exists at block 312.

[0256] FIG. 16 is a flowchart depicting another example of the open circuit check technique described above that can be used in a surgical system. FIG. 15 Similar to FIG. 16 the difference is that, in FIG. 16 the control circuit can compare a rate of change of the impedance with respect to time of the biological tissue (e.g., 40 kilo-ohms per second) to a threshold value.

[0257] Referring now to FIG. 2 at block 1200, the control circuit can start a timer in response to the delivery of electrosurgical energy to biological tissue positioned between two electrodes of an electrosurgical device. In some examples, the timer can be included in a processor (e.g., the processor 54 of the control circuit 48) in the control circuit. In some examples, the control circuit can set the timer when the control circuit has determined that the tissue is ready to be driven to a final impedance endpoint value (or impedance delta value). In some examples, the processor (e.g., the processor 54 of the control circuit 48) can control the measurement circuit (e.g., the measurement circuit 46 of the control circuit 48) to measure an impedance value of the tissue, and the processor can determine whether a representation of the measured impedance exceeds a threshold value. In some examples, the representation of the impedance includes a value of the impedance, such as an absolute value of the impedance. In other examples, the representation of the impedance includes a change in the value of the impedance (or "delta") with respect to time, such as a first derivative of the impedance with respect to time. FIG. 2 at block 1202, the control circuit can determine whether the elapsed time is less than or equal to a timer limit. If the control circuit determines that the elapsed time is less than or equal to the timer limit (the "Yes" branch of block 1202), the control circuit can reduce the delivery of electrosurgical energy and indicate an open circuit at block 1204. If the control circuit determines that the elapsed time is not less than or equal to the timer limit (the "No" branch of block 1202), the control circuit can reduce the delivery of electrosurgical energy and indicate that a good seal exists at block 1206.FIG. 2 the processor 54 of the control circuit 48) can control the measurement circuit (e.g., the measurement circuit 46 of the electrosurgical device 10) to measure an impedance value of tissue positioned between two electrodes of the electrosurgical device (e.g., the forceps 14 of the electrosurgical device 10). FIG. 1 FIG. 2

[0258] At block 1202, the processor can determine whether the timer is greater than a timer limit (e.g., 50 ms to 100 ms). If the timer has not exceeded the time limit (“No” branch of block 1202), at block 1204, the system can continue delivery of electrosurgical energy. If the timer has satisfied the time limit (“Yes” branch of block 1202), at block 1206, the processor can compare the rate of change of the measured impedance with respect to time to a first threshold (end point value). The first threshold can be stored in a memory (e.g., the memory 56 of the control circuit 48). A non-limiting example of a rate can be 2000 ohms over a 50 ms time period, or 40,000 ohms / second. FIG. 2

[0259] At block 1208, if the processor determines that the rate of change of the measured impedance is less than the first threshold (“Yes” branch of block 1208) (end point value), at block 1204, the processor can continue delivery of electrosurgical energy. If the processor determines that the rate of change of the measured impedance is not less than the first threshold (“No” branch of block 1208), at block 1210, the processor can compare the rate of change of the measured impedance to a second threshold (open circuit value). The second threshold can be stored in a memory (e.g., the memory 56 of the control circuit 48). FIG. 2

[0260] If the processor determines that the rate of change of the measured impedance is less than the second threshold (“Yes” branch of block 1210), at block 1212, the processor can reduce or terminate delivery of electrosurgical energy. Here, the rate of change is greater than the first threshold (end point value) and less than the second threshold (open circuit value), which indicates that a good seal has been achieved. In some examples, the control circuit can generate a notification to the user to indicate a good seal.

[0261] If the processor determines that the rate of change of the measured impedance is not less than the second threshold (“No” branch of block 1210), at block 1214, the processor can reduce or terminate delivery of electrosurgical energy. Here, the rate of change is greater than the first threshold (end point value) and also equal to or greater than the second threshold (open circuit value), which indicates that an open circuit exists. In some examples, the surgical system can generate an indication to the user to indicate an open circuit. For example, a user interface (e.g., the user interface 52 of the control circuit 48) can generate a notification to the user to indicate an open circuit. FIG. 17 ​​​​The user interface 50 of the surgical system of FIG. 1 can generate one or both of an audible indication and a visual indication to the user to indicate that delivery of electrosurgical energy has terminated and an open circuit is detected.

[0262] By using the open circuit check technique described above, the system can provide a good seal indication with fewer errors.

[0263] Alternating power correction output in low-precision hardware systems FIG. 1

[0264] Electrosurgical generators are constantly evolving with new "state-of-the-art" hardware that enables the generators to be more precise and more responsive to feedback from the tissue they are intended to modify. Improvements in hardware architecture can provide a number of benefits over their less advanced or historical counterparts, such as providing higher CPU speed, which can allow for faster response in gathering, analyzing data and reacting to the data, and providing new functionality that allows for phase angle calculations, for example, which can provide more accurate indications of feedback-based derived data such as power delivery, impedance, etc.

[0265] It is generally desirable to take advantage of the performance of new "state-of-the-art" hardware with existing hardware already placed in hospitals, thereby utilizing the older asset devices of such placements to provide the same performance to users without having to update to new asset devices. Such performance improvements can be important in some electrosurgical applications to ensure the best possible tissue modification performance for patients.

[0266] For example, in providing optimal tissue performance in vessel sealing, proper power delivery can be important. Delivering too much energy too quickly can cause tissue damage from steam pockets within the tissue. Slowly applying energy can significantly lengthen the procedure time and cause the patient to be under anesthesia for a longer period of time, which can cause a decrease in the benefits of the procedure results and a higher risk of patient recovery issues. From a competitive standpoint, fast tissue modification with a high level of confidence in the correct tissue effect as a result can be important for having a market-acceptable device.

[0267] Many older electrosurgical systems can not have the ability to precisely measure the phase angle of the RF output. Changes in tissue clamped between the jaws during a sealing procedure and its interaction with the inherent inductance and capacitance in the output circuit can cause a change in the phase angle in the RF waveform. If this phase angle is not accounted for, the calculations of power and load resistance can be inaccurate, and thus measuring this parameter can increase the precision of the system.

[0268] ​When voltage ("E") leads current ("I"), it is helpful to remember with the mnemonic "ELI" that the load is considered inductive. When current ("I") leads voltage ("E"), it is helpful to remember with the mnemonic "ICE" that the load is considered capacitive. In either "ELI" or "ICE" cases, the result of the phase angle shift is a reduction in actual power delivery compared to the apparent power delivery that the electrosurgical generator believes it is providing due to the misalignment of the current and voltage peaks.

[0269] The precision of the applied voltage further complicates the issue. As the voltage decreases, the precision of the voltage application of older systems can become difficult, especially when the voltage has been generated to control a high rate intended for monopolar output (e.g., 4000V or higher) that is then applied to a bipolar output that can be as low as tens of volts or lower. This can cause hardware manufacturers to create "tuned hardware" that is tuned to obtain precision within a specific impedance and voltage range in which the device is typically required to work with the desired phase shift. In lower impedance ranges, the precision of the power delivery calculation can become very difficult due to the voltage levels being so low.

[0270] As an example, to supply a certain power (e.g., 100W), the system supplies a current (I) at a voltage (V) to meet the power requirement. The impedance determines the composition of the voltage and current used to deliver the required power. For example, if the impedance is 5 ohms, the electrosurgical generator can provide a 4.5A output at 22.22V.

[0271] As another example, if the same system attempts to deliver 30W (31.25W) to an impedance of 5 ohms, the electrosurgical generator can provide an output of about 2.5A at 12.5V. Consider this 12.5V output on a system set to provide up to 4000V in some cases. The impedance range in which older electrosurgical systems become less accurate is typically about 0 ohms to 50 ohms. For such impedance ranges, older electrosurgical systems can have difficulty applying enough current to burn off fluids in the tissue to provide a good seal because the power output of the electrosurgical generator is not precise enough.

[0272] The present inventors have recognized a need to improve power control in conventional electrosurgical systems. To address this need, the present inventors have recognized that applying a power correction at lower impedance values can improve power control in conventional electrosurgical systems and overcome deficiencies in their precision.

[0273] As FIG. 1 shown, FIG. 1The surgical system may include an electrosurgical device such as forceps 14. Forceps 14 may include two jaws, such as a first jaw member 36 and a second jaw member 38. In some examples, one of the two jaws may be movable, while the other jaw may be fixed. In other examples, both jaws may be movable.

[0274] It should be noted that the power correction techniques described in this disclosure are not limited to electrosurgical devices including clamps. Rather, power correction techniques can be implemented using devices such as scrapers and ligatures.

[0275] Electrosurgical devices (e.g., forceps 14) may include two or more electrodes, which are sized, shaped, and / or otherwise configured to deliver electrotherapy signals to biological tissue (e.g., FIG. 1 (Organization 16). In some examples, the electrodes can be coupled with jaws (e.g., as shown in the image). FIG. 2 The first jaw member 36 and the second jaw member 38 are integrated. In other examples, the electrodes may be coupled to the jaws.

[0276] Output circuit (e.g., including) FIG. 2 The power supply 44) can be configured to generate electrosurgical energy and deliver the electrosurgical energy to the output terminal (e.g., FIG. 1 The instrument interface 42) is used for delivery to the patient. The output terminal can be configured to couple to an electrosurgical device (e.g., FIG. 1 The forceps 14), and deliver electrosurgical energy (e.g., high frequency such as RF energy) to the biological tissue via electrotherapy signals. The control circuitry of the surgical system (e.g., FIG. 17 The control circuit 48 of the surgical system can be coupled to the output circuit, and the control circuit can be configured to perform various aspects of the power correction technique.

[0277] FIG. 2 This is a flowchart depicting an example of a power correction technique that can be used in a surgical system. At box 1300, the measurement circuit (e.g., FIG. 1 The measurement circuit 46) measures the positioning of the electrosurgical device (e.g., FIG. 2 The impedance of the tissue between the two electrodes of the clamp 14) is represented. In some examples, the control circuit can measure the central tendency (e.g., mean, median, mode, or other central tendency) of the output during a portion of the period (e.g., the last 50ms of the output) and store these values, for example... FIG. 2 In memory 56.

[0278] At block 1302, the control circuit can compare the measured impedance with the data stored in memory (e.g., ...). FIG. 2the first threshold value (e.g., about 50 ohms) in memory 56 of the electrosurgical system. The first threshold value (e.g., 50 ohms) can be based on an impedance value below which the electrosurgical system needs to make a power correction. The first threshold value can be adjusted based on the electrosurgical system.

[0279] If the impedance is not less than the first threshold value (NO branch of block 1302), the impedance is high enough such that the control circuit does not need to impose a power correction to the power control of the electrosurgical generator, as shown in block 1304. The electrosurgical system can impose power via normal operation.

[0280] However, if the impedance is less than the first threshold value (YES branch of block 1302), the control circuit can impose a power correction to the power control of the electrosurgical generator. For example, as shown in block 1306, the control circuit can determine whether the measured impedance is within a first impedance range (e.g., 0 ohms to 100 ohms). If the measured impedance is within the first impedance range (YES branch of block 1306), the control circuit can select a first power correction associated with the first impedance range and impose the selected first power correction at block 1308.

[0281] If the measured impedance is not within the first impedance range (NO branch of block 1306), the control circuit can select a second power correction associated with a second impedance range (e.g., 20 ohms to 100 ohms) when the representation of the impedance is within the second range (e.g., 20 ohms to 100 ohms) and impose the selected second power correction at block 1310. As an example, the “desired power” can be 100 W, but in reality, the system can measure only 50 W. A correction factor can be applied to the measured value to ensure the correct compensation is applied to the output.

[0282] The electrosurgical system can impose the power correction using a linear calculation, such as the following equation:

[0283] Corrected Power = (((Zload x A) + B) x Measured Power) / 1000 Equation (1)

[0284] where Zload is the measured impedance of the tissue, A and B are specific power correction values or parameters that can be selected to provide different possible power correction trajectories, and Measured Power is the power (V x I) that the electrosurgical system believes it is providing to the tissue. The processor (e.g., processor 54 of the electrosurgical system) can retrieve the first threshold value (e.g., 50 ohms) from memory (e.g., memory 56 of the electrosurgical system). FIG. 2 FIG. 17 ​The A and B parameters are retrieved by the control circuit (e.g., from memory 56 of the control circuit 52) and the corrected power setting is calculated using the above equation (1). In a first non-limiting example for purposes of illustration, a first calculation for a power correction of 10 ohms can use a value of 11 for A and a value of 548 for B. In a second non-limiting example for purposes of illustration, a first calculation for a power correction of 50 ohms can use a value of 11 for A and a value of 419 for B.

[0285] Using the corrected power setting, the control circuit can deliver electrosurgical energy via the electrode of the electrosurgical device. In some examples, the control circuit can reduce or terminate the application of the selected power correction to the power setting when the representation of impedance meets or exceeds a threshold value. Continuing the example described above, the control circuit can initially apply a power correction for a measured impedance of 15 ohms (which is below 50 ohms and within a first range of 0 ohms to 20 ohms) and reduce or terminate the application of the power correction when the measured impedance exceeds 20 ohms (which is above the upper limit of the first range). In some examples, the control circuit can begin applying a new power correction based on a change in impedance. Continuing the example described above, for a measured impedance of 21 ohms (which is below 50 ohms and within a second range of 20 ohms to 50 ohms), the control circuit can apply a new power correction to the power setting.

[0286] In some examples, rather than having a single impedance value (e.g., 20 ohms) that is the difference between a first range (e.g., 0 ohms to 20 ohms) and a second range (e.g., 20 ohms to 50 ohms), it can be desirable for the control circuit to use hysteresis to prevent the system from oscillating between two power corrections. When implemented, hysteresis can dynamically change the threshold limits depending on the current “state” of the system, which can prevent inadvertent oscillation between at least two threshold values when the measured parameter is near the threshold value. It can affect one or both of the upper and lower portions of the threshold value. In this way, the control circuit can dynamically adjust at least one of the upper and lower limits of the first range when the representation of impedance is within a predetermined percentage of the upper or lower limit or within the upper or lower limit value.

[0287] For example, a specified percentage can be used at the boundary of the range. As an example, for a measured impedance that is within 20% of the 20 ohm upper limit of the first range, the control circuit can use one or both of the upper and lower limits associated with the first range that can be dynamically adjusted (e.g., increased).

[0288] In another example, rather than using a percentage for hysteresis, the control circuit can use a specified impedance value at the boundary of a range. As an example, for a measured impedance that is within 4 ohms of the 20 ohm upper limit of the first range, the control circuit can dynamically adjust (e.g., increase) one or both of the upper and lower limits associated with the first range.

[0289] It should be noted that while two non-limiting examples of ranges are described with two corresponding power corrections, in some examples, only one range can provide sufficient power correction. In other examples, more than two ranges with corresponding power corrections can be used.

[0290] The power correction techniques described above can significantly improve power control of an electrosurgical system to artificially overcome deficiencies in accuracy. However, in some examples, secondary parameters can be used to provide even higher accuracy. For example, the power correction can be based on output during a "tissue sampling" phase. If the tissue has one characteristic, a first power correction can be used. If the tissue has another characteristic, a second power correction can be used. Examples of characteristics that can be used to determine the power correction include, but are not limited to: energy delivered over a period of time, calculated impedance, current draw, voltage phase angle, tissue temperature, etc. The processor can use these characteristics individually or in combination to select the power correction. For example, the processor can use tissue temperature and calculated impedance to select the power correction.

[0291] In examples that utilize one or more secondary parameters to determine the power correction, the measurement circuit can measure a representation of impedance of tissue positioned between two electrodes of an electrosurgical device, compare the measured representation of impedance to a first threshold, and if the impedance is less than the first threshold (e.g., 50 ohms), as described above with respect to FIG. 24 the first power correction is selected from two or more power corrections. The control circuit can then compare a representation of one or more secondary parameters to one or more thresholds. When the representation of the secondary parameter(s) is less than the threshold(s), the control circuit can select between the previously selected first power correction and one or more other power corrections. The control circuit can determine that the previously selected first power correction is sufficient, or it can determine that a different power correction would be expected to be applied to the power setting based on the secondary parameter (e.g., output current of the power generator), tissue temperature, and voltage phase angle.

[0292] In some examples, if the impedance is less than the first threshold (e.g., 50 ohms), the control circuit can select a secondary power correction. As the impedance increases, the control circuit can then select the first power correction. As the increase continues to increase, the adjusted power setting can utilize standard generator control without any power correction.

[0293] In some examples, power correction can be used for a specific time period (e.g., using tissue feedback). For example, using the corrected power setting, the control circuit can deliver electrosurgical energy via the electrode of the electrosurgical device over a range of impedance values during a period of time or until a certain amount of energy is applied, or a combination of both. Additionally, external metrics such as a time period or user settings can be applied.

[0294] FIG. 24 is a flowchart depicting another example of a power correction technique that can be used in a surgical system. FIG. 18 A dual decision flowchart is described that can use impedance to decide which power correction to apply. Additionally, the flowchart can also use impedance as a decision point for when to apply power correction and when to stop applying power correction.

[0295] At block 2400, stage 1A can be complete and the generator output can be stable. At block 2402, stage IB can begin and the control circuit can determine the average impedance of the tissue during the last 50 ms of stage IB. At block 2404, the control circuit can determine whether the average impedance is between 0 ohms and 20 ohms. If the average impedance is between 0 ohms and 20 ohms (‘YES’ branch of block 2404), then at block 2406, the control circuit can use a first power correction value ‘X’ for stage 2.

[0296] If the average impedance is not between 0 ohms and 20 ohms (‘NO’ branch of block 2404), then at block 2408, the control circuit can determine whether the average impedance is between 20.01 ohms and 50 ohms. If the average impedance is between 20.01 ohms and 50 ohms (‘YES’ branch of block 2408), then at block 2410, the control circuit can use a second power correction value ‘Y’ for stage 2. If the average impedance is not between 20.01 ohms and 50 ohms (‘NO’ branch of block 2408), then at block 2412, the control circuit can determine that stage 2 does not require power correction.

[0297] Reduced thermal margin combination energy device FIG. 19 and FIG. 18 )

[0298] There are surgical systems that can deliver two types of energy - ultrasonic energy and electrosurgical energy, e.g., high frequency energy. The ultrasonic energy can provide fast and precise tissue cutting and the electrosurgical energy can provide reliable vessel sealing. The system can deliver both types of energy simultaneously or the system can control the delivery such that the two types of energy are delivered separately.

[0299] FIG. 2This is a simplified block diagram of an example of a combined ultrasonic energy and electrosurgical energy system that can implement various techniques of the present disclosure. System 1400 may include a surgical device 1402 coupled to an ultrasonic drive unit 1404 and an electrosurgical drive unit 1406. Additional information regarding such a combined ultrasonic energy and electrosurgical energy system can be found in US 8,574,228, co-transmitted by Okada et al., entitled “ULTRASOUND TREATMENT SYSTEM,” the entire contents of which are incorporated herein by reference. Surgical device 1400 may include an ultrasonic transducer 1408 and a probe 1410. Ultrasonic drive unit 1404 may include a first output circuit 1412 configured to generate a drive signal applied to ultrasonic transducer 1408 to generate ultrasonic vibrations delivered to biological tissue via probe 1402.

[0300] System 1400 may include control circuitry configured to control various aspects of the operation of the ultrasound drive unit 1404 and the electrosurgical drive unit 1406. For example, control circuitry 1414 may be configured to generate and apply signals to a first output circuit 1412 of the ultrasound drive unit 1404, and to generate and apply signals to a second output circuit 1416 of the electrosurgical drive unit 1406. In some example configurations, control circuitry 1414 may include... FIG. 2 The control circuit 48 is similar to the component, and is related to FIG. 2 The control circuit 48 operates similarly. In some example configurations, the electrosurgical drive unit 1406 may include... FIG. 2 Similar components to the electrosurgical generator 12, and with FIG. 1 The electrosurgical generator 12 operates similarly. The second output circuit 1416 can generate a high-frequency electrotherapy signal to be delivered to biological tissue via probe 1410. The first output circuit 1412 and the second output circuit 1416 are coupled to control circuitry 1414 and configured to generate energy and deliver it to the system's output terminals for delivery to the patient. In some examples, the system may include a speaker 1418 and / or a display 1422 to provide the user with alarms or other auditory and / or visual notifications.

[0301] In some examples, the surgical device 1402 may be similar to U.S. Patent Application Publication No. US20120010539, co-assigned by Yachi et al. and entitled “OPERATION DEVICE AND SURGICAL APPARATUS”. FIG. 1 Surgical devices, the entire contents of which are incorporated herein by reference. U.S. Patent Application Publication No. US20120010539FIG. 2 Surgical equipment can perform procedures such as cutting and removing living tissue by using ultrasound combined with the application of high-frequency waves. Additionally, ultrasound can be used to coagulate living tissue.

[0302] In some examples, the electrosurgical drive unit 1406 may include measurement circuitry 1420. Measurement circuitry 1420 may be similar to... FIG. 18 The measurement circuit 46 can be configured to measure one or more electrical parameters of biological tissue coupled to the surgical device 1402.

[0303] Appropriate power delivery is a crucial factor in achieving optimal tissue efficacy during vascular occlusion. Too much energy, too fast, can create a vapor pocket within the tissue, potentially causing damage to the tissue surrounding the surgical instrument. This phenomenon is commonly referred to as "thermal margin." Combined ultrasound and electrosurgical energy systems often use waveforms with slack-rate outputs, such as constant pulse rates or high-frequency energy (e.g., RF energy), along with ultrasound energy, and layer them on top of each other. This can lead to undesirable consequences such as heating of the surgical instrument tip and increased thermal margin.

[0304] The inventors have recognized the need to monitor feedback from the tissue in combined ultrasound and electrosurgical energy systems to determine whether a desired vapor bag has been generated. Using various techniques described below, combined ultrasound and electrosurgical energy systems can monitor feedback from the tissue, such as changes in the drawn current, changes in impedance, or changes in impedance over time, to provide an indication that a desired vapor bag has been generated. Instead of continuing to apply energy to the tissue, one or both of the high-frequency energy (e.g., RF energy) and ultrasound energy can be reduced or stopped.

[0305] The use of combined ultrasound energy and electrosurgical energy systems (e.g., FIG. 18 System 1400) is a non-limiting, specific example of modifying biological tissue using various techniques described herein. The combined ultrasound and electrosurgical energy system can deliver energy in at least two modes: a first mode comprising ultrasound energy and a second mode comprising bipolar energy. Control circuitry (e.g., FIG. 18 The control circuit 1414 can control the measurement circuit (e.g., FIG. 18 The measurement circuit 1420 measures a representation of tissue impedance to monitor feedback from tissue in contact with the surgical device. For example, the control circuit can monitor changes in the impedance value, which may indicate that a maximum preferred amount of vapor has been generated in the tissue, and that additional vapor generation may cause excessive heat margin. In other example implementations, the control circuit may monitor changes in the drawn current and / or impedance value (e.g., absolute impedance value).

[0306] Once the change in impedance value reaches or exceeds the threshold, the control circuit can control the ultrasonic drive unit (e.g., FIG. 18 ultrasonic drive unit 1404) to stop ultrasonic output. Additionally, the control circuit can control the electrosurgical drive unit (e.g., FIG. 18 electrosurgical drive unit 1406) to reduce the output of the high frequency therapeutic signal generated by the second output circuit 1416 of the electrosurgical drive unit 1406. For example, the high frequency output can be reduced to a level at which the steam generated in the tissue can partially or fully revert to a liquid. Once this liquid state is achieved, as determined by the control circuit using a set time, feedback control, or both, the system 1400 can again apply power until such time that the steam generation limit is met, or the end of the energy application period is met, e.g., by user decision or by feedback control.

[0307] FIG. 18 is a flowchart depicting an example of a reduced thermal margin technique that can be used in a combined ultrasonic and electrosurgical energy system. At block 1500, a control circuit can control delivery of energy to biological tissue positioned between two electrodes of an electrosurgical device, where the delivered energy includes at least some ultrasonic energy. For example, FIG. 18 the control circuit 1414 of the ultrasonic device 1402 can control the first output circuit 1412 to deliver ultrasonic energy to tissue in contact with the FIG. 18 electrosurgical device 1402, and control the second output circuit 1416 to deliver high frequency energy (e.g., RF energy) to tissue in contact with the FIG. 18 electrosurgical device 1402. For example, the electrosurgical device can include an ultrasonic forceps having an HF electrode on its jaws.

[0308] At block 1502, a measurement circuit can measure a representation of a tissue parameter (e.g., impedance) of the biological tissue. For example, FIG. 20 the measurement circuit 1420 of the ultrasonic device 1402 measures a change in the drawn current and / or an impedance value (e.g., an absolute impedance value or a change in impedance (relative value)).

[0309] At block 1504, the control circuit can reduce the level of energy delivery or terminate energy delivery based on a characteristic of the measured representation of the tissue parameter of the biological tissue. Example characteristics can include, but are not limited to, the following: electrical resistance, impedance, current, phase angle, current drawn, and / or voltage required, as well as a change (delta) in one or more of these characteristics, as well as combinations of these characteristics. For example, FIG. 21 the control circuit 1420 of the ultrasonic device 1402 can control FIG. 2 the first output circuit 1412 to reduce the level of ultrasonic energy. In some examples, the control circuit 1420 can control the first output circuit 1412 to terminate or reduce delivery of ultrasonic energy. Termination is an example of a reduction in the delivery of ultrasonic energy.

[0310] In some examples, the delivered energy can be modified, for example by increasing the energy or by temporarily reducing the energy but allowing it to return to its previous level after a short time interval. Temporarily reducing the energy can mean temporarily reducing to or near to no energy delivery, for example suspension.

[0311] In some examples, in contrast to pausing energy as an activated endpoint, the control circuit can pause delivery of energy to allow condensation of vapor. By pausing delivery of energy, the system can establish a fluid condensation dwell time. The system need not monitor tissue parameters to identify an endpoint for a coagulation high frequency / ultrasound therapy pulse.

[0312] In other examples, the control circuit 1420 can control the first output circuit 1412 to reduce a level of electrosurgical energy. In some examples, the control circuit 1420 can control the first output circuit 1412 to terminate delivery of electrosurgical energy.

[0313] For example, as described above, the electrosurgical energy can be power-controlled or voltage-controlled. In a power-controlled implementation, the control circuit 1420 can control the second output circuit 1416 to deliver electrosurgical energy using a product of a voltage applied across the engaged biological tissue and a current output by the second output circuit 1416, for example according to a plan, protocol, or schedule. For example, the control circuit can control the second output circuit 1416 to deliver a constant power or a monotonically increasing power during a particular phase (e.g., a dry phase).

[0314] In a voltage-controlled implementation, the control circuit can control a voltage of the electrosurgical energy delivered by the second output circuit 1416, for example according to a plan, protocol, or schedule. For example, the control circuit can control the second output circuit 1416 to deliver a constant voltage or a monotonically increasing voltage during a particular phase (e.g., a dry phase).

[0315] As described above, the control circuit can reduce a level of energy delivery or terminate energy delivery based on a characteristic of a representation of measured biological tissue impedance. In some examples, the characteristic of the representation of measured impedance is an impedance value, for example an absolute value or a relative value of impedance. In some such examples, the control circuit can be configured to compare the measured impedance value to a threshold value and reduce a level of energy delivery or terminate energy delivery based on the comparison. For example, the control circuit can reduce a level of delivery of one or both of the ultrasonic energy and the electrosurgical energy, periodically reduce a level of delivery of one or both of the ultrasonic energy and the electrosurgical energy, or terminate delivery of one or both of the ultrasonic energy and the electrosurgical energy based on the comparison. By periodically reducing the level, the system can reduce power at various phases during a single output, where the output is during a process of full activation.

[0316] In other examples, the characteristic of the representation of the measured impedance is a change in impedance value. In some such examples, the control circuit can be configured to compare the change in impedance value to a threshold value, and based on the comparison, reduce the level of energy delivery or terminate energy delivery. For example, the control circuit can reduce the level of delivery or terminate delivery of one or both of the ultrasonic energy and the electrosurgical energy based on the comparison.

[0317] In the case of using the above-described techniques for a combined ultrasonic energy and electrosurgical energy system, the total power output of the system can be reduced when a steam pocket is created, which can reduce the undesirable thermal margin.

[0318] Hierarchical impedance values for controlling thermal margin in systems with slow CPUs FIG. 1 and FIG. 1 )

[0319] It is generally desirable to obtain high performance without increasing the processing burden of a system. If the processing remains low, it can be better to perform with a slower system that can be less expensive to purchase or maintain.

[0320] Generally, steam control and thermal margin control for a device for vessel closure can be achieved by monitoring one or more feedback systems. The feedback system can be a single true feedback element or multiple feedback elements that are interdependent, for example, through a decision tree type structure or a calculation based on one or more events.

[0321] An example of such a system can monitor the difference (or delta) between the lowest encountered calculated impedance and the rolling upper impedance. In other examples, the rate of rise of impedance over time, the change in phase angle, the change in current drawn, and the change in voltage can be used as an indication of steam generation within the tissue.

[0322] In monitoring the difference (or delta) between the lowest encountered calculated impedance and the rolling upper impedance, for example, newer, fast reacting hardware can use specific boundaries or decision points to determine whether a steam pocket has been created and, if so, whether the size of the pocket is such that power should be reduced, briefly stopped, or stopped completely. In older, slower reacting systems, the speed at which a steam pocket is created is the same, but the reaction time to reduce or stop power is slower, which can cause a "steam pocket overshoot" that can cause greater thermal margin.

[0323] As an example, if the impedance threshold is set at 55 ohms, older, slower systems may exceed the 55-ohm threshold and stop at 70 ohms. In contrast, newer electrosurgical systems may include faster analog-to-digital converters, processors, and other hardware that allows sampling at millions of samples per second. In such systems, if the impedance threshold is set at 55 ohms, the newer system may stop at the desired level of approximately 55 ohms.

[0324] The inventors have recognized the need to improve thermal margin control in conventional electrosurgical systems. Through extensive observation of tissue effects, the inventors have realized that overshoot typically occurs in the early pulse phase of the electrosurgical waveform, and the rate of vapor generation decreases throughout the waveform as tissue dries through fluid drainage. Therefore, to address the overshoot problem and improve thermal margin control, the inventors have recognized the desire to incorporate intelligence into the output. In particular, the inventors have realized that electrosurgical systems can count the pulses of the electrosurgical signal and can assign different values ​​of triggers or thresholds, such as impedance values ​​or impedance increments, based on the number of pulses. In this way, the threshold of one or more initial electrosurgical energy pulses can be reduced, which can allow overshoot and thus reduce the thermal margin of conventional electrosurgical systems.

[0325] As mentioned above, FIG. 1 Examples of surgical systems that can be used to implement various aspects of the thermal margin control techniques of this disclosure are described. For example... FIG. 1 As shown, FIG. 2 The surgical system may include an electrosurgical device such as forceps 14. Forceps 14 may include two jaws, such as a first jaw member 36 and a second jaw member 38. In some examples, one of the two jaws may be movable, while the other jaw may be fixed. In other examples, both jaws may be movable.

[0326] It should be noted that the thermal margin control techniques disclosed herein are not limited to electrosurgical devices including clamps. Rather, thermal margin control techniques can be implemented using devices such as scrapers and ligatures.

[0327] Electrosurgical devices (e.g., forceps 14) may include two or more electrodes, which are sized, shaped, and / or otherwise configured to deliver electrotherapy signals to biological tissue (e.g., FIG. 2 (Organization 16). In some examples, the electrodes can be coupled with jaws (e.g., as shown in the image). FIG. 1 The first jaw member 36 and the second jaw member 38 are integrated. In other examples, the electrodes may be coupled to the jaws.

[0328] Output circuit (e.g., including) FIG. 1Power supply 44) can be configured to generate and deliver electrosurgical energy to output terminals (e.g., FIG. 20 Instrument interface 42) of electrosurgical system 10 to be delivered to a patient. The output terminals can be configured to be coupled to an electrosurgical device (e.g., FIG. 2 Forceps 14) and deliver electrosurgical energy (e.g., high frequency such as RF energy) to biological tissue via the electrotreatment signal. Control circuitry (e.g., FIG. 2 Control circuitry 48 of the electrosurgical system can be coupled to the output circuitry, and the control circuitry can be configured to perform various aspects of a thermal margin control technique.

[0329] FIG. 2 is a flowchart depicting an example of a thermal margin control technique that can be used in an electrosurgical system. At block 1600, a user such as a surgeon or clinician can initiate delivery of electrosurgical energy to biological tissue of a patient (e.g., tissue positioned between two forceps of an electrosurgical device). At block 1602, control circuitry (e.g., FIG. 2 Control circuitry 48 of system 10) can count a number of delivered electrosurgical pulses.

[0330] At block 1604, the control circuitry can compare a parameter to a threshold value. In some examples, the parameter can be an impedance of the biological tissue, a change (or delta) in impedance of the biological tissue, a rate of change of the impedance of the biological tissue, a change in current of the delivered electrosurgical energy pulses, a change in output voltage of the delivered electrosurgical energy pulses, or a change in a phase angle (e.g., a phase angle between a voltage difference delivered across the biological tissue and a current conducted by the biological tissue). In some examples, a measurement circuit (e.g., FIG. 2 Measurement circuit 46) of system 10 measures the parameter or electrical characteristics that can be used by the control unit (e.g., FIG. 2 Processor 54) to calculate the parameter. In some examples, the control circuitry can reduce delivery of a plurality of electrosurgical energy pulses when a representation of the measured impedance meets or exceeds an endpoint value (e.g., an endpoint value of about 100 ohms to 600 ohms).

[0331] At block 1606, the control circuitry can adjust the threshold value based on the count of electrosurgical energy pulses. That is, the threshold value can change from pulse to pulse. For example, for a second pulse, the control circuitry can adjust the impedance delta upward from, for example, 40 ohms to 45 ohms. In this way, the control circuitry can set the threshold value or boundary based on the count of pulses. Customizing the threshold value for one or more initial electrosurgical pulses based on the count of pulses can help address any overshoot caused by delays in older, slower reacting electrosurgical generator systems.

[0332] As a non-limiting example, it can be desirable to deliver an energy pulse that produces an impedance change (or impedance delta) of about 55 ohms in biological tissue. When a user initiates delivery of a first pulse of electrosurgical energy, the control circuit (e.g., control circuit 48 of FIG. 2 ) can reset a counter (e.g., within processor 54 of FIG. 21 ) and set a threshold value for a parameter (e.g., change in impedance) to a first value. For example, the control circuit can retrieve data representing the threshold value for the first pulse from a memory device (e.g., memory 56 of FIG. 2 ) and set the threshold value for the impedance delta of the first pulse to the retrieved data (e.g., representing 40 ohms).

[0333] The system can deliver the first pulse of energy and the control circuit can compare the measured parameter (e.g., impedance delta) to the threshold value of 40 ohms. Once the measured parameter reaches 40 ohms, the control circuit can stop delivery of the first pulse. Due to delays in older electrosurgical generator systems that react more slowly, the system can exceed the threshold value of 40 ohms and actually stop once the impedance delta reaches about 55 ohms. The lowered threshold value for the first pulse can allow for a fast rise of the first pulse that provides an actual impedance of 55 ohms due to the system reacting slowly in the event of an overshoot. As mentioned above, in some examples, the impedance delta of 55 ohms can be desirable.

[0334] Next, in preparation for delivering a second pulse, the control circuit can adjust the threshold value based on the count of electrosurgical pulses. Here, the count is two and the control circuit can retrieve data representing the threshold value for the second pulse from the memory device and set the threshold value for the impedance delta of the second pulse to the retrieved data (e.g., representing 45 ohms).

[0335] The system can deliver the second pulse of energy and the control circuit can compare the measured parameter to the adjusted threshold value of 45 ohms. Once the measured parameter reaches 45 ohms, the control circuit can stop delivery of the second pulse. Due to delays, the system can exceed the threshold value of 45 ohms and actually stop once the impedance delta reaches about 55 ohms. The adjusted threshold value for the second pulse can allow for a slightly slower ramp rate of the second pulse that provides an actual impedance of 55 ohms due to the system reacting slowly.

[0336] Next, in preparation for delivering a third pulse, the control circuit can adjust the threshold value based on the count of electrosurgical pulses. Here, the count is three and the control circuit can retrieve data representing the threshold value for the third pulse from the memory device (or use the previously retrieved data) and set the threshold value for the impedance delta of the third pulse to the retrieved data (e.g., representing 55 ohms).

[0337] The system can deliver a third pulse of energy, and the control circuit can compare the measured parameter to an adjusted threshold of 55 ohms. Once the measured parameter reaches 55 ohms, the control circuit can stop the delivery of the third pulse. With the third pulse, the ramp rate can be slow enough that once the impedance delta reaches 55 ohms, the system can react in time and stop.

[0338] In this way, the threshold of one or more of the initial electrosurgical energy pulses can be artificially lowered, as the desired threshold of, for example, 55 ohms remains the same despite the adjustments of 40 ohms, 45 ohms, etc. This artificial lowering of the threshold can allow for overshoot, and thus reduce the thermal margin of traditional electrosurgical systems. The thresholds of additional pulses such as the fourth pulse, the fifth pulse, and higher can not need to be adjusted. For example, the fourth pulse, the fifth pulse, and higher can be set at, for example, 55 ohms. In other examples, the third pulse, the fourth pulse, the fifth pulse, and higher can be adjusted.

[0339] In addition to the tiered pulse capabilities described above, the control circuit can use a predictor to determine or select a set of pulse ratios to use. For example, the ratios can be between each of the adjusted thresholds and the desired threshold. As a non-limiting example for illustrative purposes only, if the desired threshold is 55 ohms and the first pulse threshold, the second pulse threshold, and the third pulse threshold are 40, 45, 50, respectively, the ratios can be 40 / 55, 45 / 50, and 50 / 55.

[0340] The predictor can identify the likelihood of an impedance rise and account for the impedance rise in the calculation of the adjusted thresholds. For example, tissue with a high initial impedance that drops to a low impedance in the first pulse can indicate a rapid rise, and thus a reduced percentage of impedance delta being searched for. This can be because tissue with a higher initial impedance that drops suddenly can indicate tissue with a large amount of fluid and thus a rapid vapor rise. However, tissue that starts with a lower impedance delta and drops lower can have a different ratio selector or set of thresholds.

[0341] Various parameters that can be used as predictors can include: the impedance of the biological tissue, the change (or delta) in impedance of the biological tissue, the rate of change of the impedance of the biological tissue, the change in current of the delivered electrosurgical energy pulse, the change in output voltage of the delivered electrosurgical energy pulse, or the change in phase angle (e.g., the phase angle between the voltage difference delivered across the biological tissue and the current conducted by the biological tissue).

[0342] In some examples, the control circuit (e.g., FIG. 2The control circuit 48) can compare the first measured parameter to the second measured parameter and adjust the threshold based on a difference between the first measured parameter and the second measured parameter. For example, the measurement circuit (e.g. FIG. 2 The measurement circuit 46) can measure, for example, a first impedance increment prior to delivering the first pulse and a second impedance increment, for example, after delivering the first pulse. Based on a difference between the first impedance increment and the second impedance increment, the control circuit can select a particular set of adjusted impedance increments.

[0343] As a non-limiting example, the control circuit can have an initial selected first set of adjusted impedance increment thresholds for the first, second, and third pulses, for example, 40 ohms, 45 ohms, and 55 ohms, respectively. However, based on a difference between the first impedance increment and the second impedance increment, the control circuit can select a second set of adjusted impedance increment thresholds for the first, second, and third pulses, for example, 45 ohms, 50 ohms, and 55 ohms, respectively.

[0344] In some examples, the control circuit can adjust the threshold based on the first measured parameter being greater than the second measured parameter. In other examples, the control circuit can adjust the threshold based on the first measured parameter being less than the second measured parameter. In some examples, the control circuit can adjust the threshold based on a rate of change between the first measured parameter and the second measured parameter.

[0345] Other factors can also be used to predict the correct ratio to use. For example, the rate of decrease of the initial impedance over time can be used to indicate the rate of rise, and thus the correct threshold or trigger. Additionally, the initial impedance or even a previous tissue activation can be used as a predictor. The previous tissue activation can be, for example, the last time the surgeon grabbed the tissue and pressed the activation button.

[0346] FIG. 2 is a flowchart depicting another example of a thermal margin control technique that can be used in an electrosurgical system. The control circuit (e.g., FIG. 2 The control circuit 48) of the system 10 can count the number of electrosurgical pulses delivered. In some examples, the control circuit can retrieve data representing the first (and more) threshold(s) from a memory device (e.g., FIG. 20 The memory 56) of the system 10. At block 1700, a user, such as a surgeon or clinician, can initiate delivery of a first electrosurgical energy pulse to biological tissue of a patient, for example, tissue positioned between two jaws of an electrosurgical device.

[0347] At block 1702, the control circuit can compare a first measured impedance representation (e.g., impedance delta) of the biological tissue to a first threshold (e.g., 40 ohms). In some examples, the measured representation of impedance can be: an impedance of the biological tissue, a change (or delta) in impedance of the biological tissue, a rate of change of impedance of the biological tissue, or a current change of the delivered electrosurgical energy pulse. In some examples, the measurement circuit (e.g., measurement circuit 46 of FIG. 2 the control unit (e.g., processor 54 of the control unit 52) uses to calculate the impedance representation. In some examples, the control circuit can reduce the delivery of the plurality of electrosurgical energy pulses when the measured impedance representation meets or exceeds an endpoint value (e.g., an endpoint value of about 250 ohms to 350 ohms). FIG. 2

[0348] At block 1704, the control circuit can reduce or terminate the delivery of the first electrosurgical energy pulse when the first measured impedance representation meets or exceeds the first threshold. For example, the control circuit can reduce or terminate the delivery of the first pulse when the measured impedance delta meets or exceeds the threshold of 40 ohms associated with the first pulse.

[0349] At block 1706, the control circuit can increase the first threshold to a second threshold based on the count of the pulses. For example, based on the count being two, the control circuit can increase the impedance delta threshold of 40 ohms associated with the first pulse to an impedance delta threshold of 45 ohms associated with the second pulse.

[0350] At block 1708, the control circuit can control the electrosurgical generator (e.g., electrosurgical generator 12 of FIG. 20 ) to deliver a second electrosurgical energy pulse to the tissue. At block 1710, the control circuit can compare a second measured impedance representation (e.g., impedance delta) of the biological tissue to a second threshold (e.g., 45 ohms).

[0351] At block 1712, the control circuit can reduce or terminate the delivery of the second electrosurgical energy pulse when the second measured impedance representation meets or exceeds the second threshold. For example, the control circuit can reduce or terminate the delivery of the second pulse when the measured impedance delta meets or exceeds the adjusted threshold of 45 ohms for the second pulse.

[0352] In some examples, the control circuit can adjust the threshold based on the count of the electrosurgical pulses in preparation for delivering a third pulse. Here, the count is three, and the control circuit can retrieve data representing the threshold for the third pulse from the memory device (or use previously retrieved data), and set the threshold for the impedance delta of the third pulse to the retrieved data (e.g., representing 55 ohms).

[0353] As described above with reference to​FIG. 21 The set of pulse ratios to be used can be determined or selected using a predictor. For example, the control circuit (e.g., control circuit 48 of FIG. 22A-22D ) can compare the first measured parameter to the second measured parameter and adjust the threshold based on a difference between the first measured parameter and the second measured parameter. For example, the measurement circuit (e.g., measurement circuit 46 of FIG. 22A-22D ) can measure a first impedance increment, e.g., prior to delivery of a first pulse, and a second impedance increment, e.g., after delivery of the first pulse. Based on a difference between the first impedance increment and the second impedance increment, the control circuit can select a particular set of adjusted impedances.

[0354] By using the thermal margin control techniques described above, e.g., with respect to FIG. 22A-22D and FIG. 22A-22D , the threshold of one or more of the initial electrosurgical energy pulses can be artificially lowered. This artificial lowering of the threshold can allow for overshoot and, thus, lower the thermal margin of conventional electrosurgical systems.

[0355] Although described separately, the above-described double boundary thresholding techniques, open circuit check techniques, power correction techniques, reduced thermal margin techniques for combined ultrasonic energy and electrosurgical energy systems, and thermal margin control techniques can be implemented individually or in combination of two or more techniques described in the present disclosure, as desired.

[0356] For example, a system implementing the double boundary thresholding techniques can also implement one or more of the above-described power correction techniques, reduced thermal margin techniques for combined ultrasonic energy and electrosurgical energy systems, and thermal margin control techniques. As a non-limiting example, for illustrative purposes only, a system implementing the double boundary thresholding techniques can also implement the thermal margin control techniques that can artificially lower the threshold.

[0357] In another non-limiting example, for illustrative purposes only, a combined ultrasonic energy and electrosurgical energy system implementing the reduced thermal margin techniques by lowering a level of delivery of energy or terminating delivery of energy based on a measured characteristic of the impedance of the biological tissue can also implement the power correction techniques that can apply a power correction to the power control of the electrosurgical generator based on whether the measured impedance is within an impedance range, e.g., 0 ohms to 20 ohms.

[0358] Consumption energy monitoring and open circuit assessment FIG. 2

[0359] ​To help determine whether to continue with an additional tissue drying phase, the inventors have recognized that at the end of the drying phase, the amount of energy (and / or charge) delivered to the tissue during the just-completed drying phase (or the just-completed interrogation and drying phases) can be assessed, as described in detail below. If the amount of energy (and / or charge) applied is below an energy (and / or charge) threshold and a sufficient impedance increment has been generated, the tissue is sufficiently dry, and processing can proceed to the next phase. However, if the amount of energy (and / or charge) applied is above an energy (and / or charge) threshold and a sufficient impedance increment has been generated, the tissue is too wet and requires another drying phase.

[0360] FIG. 2 A flowchart depicts an example of an energy delivery technology that can utilize the amount of energy delivered to biological tissues, among other things, during its decision-making process. Although... FIG. 2 The technology depicted in the flowchart is described as power-controlled, but in some examples, the technology can be voltage-controlled.

[0361] exist FIG. 22A-22D The flowchart depicts three steps, which are described in detail below. The portion of the flowchart labeled Step 1 (which could be an interrogation phase or other low-energy phase) could be a power-controlled step (or, in other examples, a voltage-controlled step), in which an electrosurgical generator (e.g., FIG. 22A The electrosurgical generator 12) can control the delivery of low-power electrotherapy signals (e.g., 10W) ​​to biological tissue. In some examples, step 1 can be considered a vapor dissipation stage, in which the vapor generated in the tissue during step 2 is allowed to dissipate to prevent thermal margin.

[0362] In some examples, step 1 can be set to run for a specific duration, such as 250 ms, during which the electrosurgical generator can control the power as tightly as possible to ensure a consistent delivery level. During step 1, the control circuitry (e.g., FIG. 2 Control circuit 48) and measurement circuit (e.g. FIG. 22B The measurement circuit 46) combination can track various parameters. For example, the control circuit and measurement circuit can initiate measurements and store the maximum and minimum impedances associated with a specific delivery pulse (pulse RMax and pulse RMin) (also tracked in step 2). Additionally, during the application of power in steps 1 and 2, the control circuit and measurement circuit can store the value of the amount of energy (and / or charge) delivered to the tissue.

[0363] The amount of energy delivered to the tissue can be measured in joules and is the integral of the amount of power delivered in watts. The amount of charge delivered to the tissue can be measured in coulombs and is the integral of the amount of current in amperes. Although the following is generally shown and described with respect to the amount of energy delivered to the tissue, the techniques of FIG. 4 can additionally or alternatively use the amount of charge delivered to the tissue.

[0364] FIG. 22A The illustrated method begins at block 1800, where the electrosurgical generator (e.g., the electrosurgical generator 12 of FIG. 2 is powered on. At block 1802, the method enters step 1, and the electrosurgical generator can deliver a constant power output “A” during a duration “B.” At block 1804, the measurement and control circuitry can read or calculate impedance values of the tissue, and then the control circuitry can average these values. In some examples, the average impedance determined during step 1 can have an impact on the selection of the ramp rate for applying energy in step 2 (the next power control phase).

[0365] At block 1806 of FIG. 22C , the method enters step 2, which can be a dry phase. At block 1806, the control circuitry can automatically select a power ramp rate based on the impedance values determined in step 1. Different segments or ranges of impedance values can result in different output power ramp rates. For example, for a lower impedance range, e.g., 1 ohm to 15 ohms, the control circuitry can select a slope “E” (block 1808) (e.g., 0.05 W / ms), while for a medium impedance range, e.g., 15 ohms to 75 ohms, the control circuitry can select a slope “D” (block 1810) (e.g., 0.035 W / ms), and for a high impedance range, e.g., 75 ohms to 400 ohms, the control circuitry can select a power slope “F” (block 1812) (e.g., 0.035 W / ms). In some examples, there can be only two slopes, e.g., a fast first slope and a slower second slope, as shown in t1 to t2 and t2 to t3 in FIG. 22D At block 1814, after the power slope is selected, the control circuitry can set the cumulative pulse energy (and / or charge) value to 0, and at block 1816, power is applied to the tissue via the electrotreatment signal.

[0366] Next, the method can perform activities in parallel, including the control circuitry reading or calculating the impedance of the tissue at block 1818 and reading or calculating the energy (and / or charge) applied during that particular phase at block 1820. In some examples, rather than running in parallel, the activities can be mixed in a single process.

[0367] At box 1820, the control circuit can read and calculate the energy (e.g., in joules) (and / or charge, e.g., in coulombs) applied to the biological tissue during this phase. Then, at box 1822, the control circuit can add the energy (and / or charge) applied during this phase to the pulse energy (and / or charge) value to generate a cumulative applied energy (and / or charge) value.

[0368] exist FIG. 1 In the example shown, and in parallel with the calculation of the applied energy, after calculating the impedance in box 1818, at box 1824... FIG. 22A-2 The control circuit 48 can determine whether the impedance is less than the previous impedance Rmin. In some examples, the control circuit can start with a default initial impedance (e.g., 1000 ohms) when determining the minimum impedance Rmin. For example, if the next measured or calculated impedance is 20 ohms, then 20 ohms is the new minimum impedance Rmin. Similarly, if the subsequent measured or calculated impedance is 15 ohms, then 15 ohms is the new minimum impedance Rmin. The minimum impedance Rmin can come from step 1 or from the current impedance reading.

[0369] If the current impedance reading is lower than the previous impedance Rmin (the "Yes" branch of box 1824), then at box 1826, the control circuit can store the current impedance reading as the new minimum resistance value Rmin. Then, at box 1828, the control circuit can increase the power, for example, along a specific power slope trajectory (power increases over time).

[0370] At block 1830, the control circuitry can determine whether the power is greater than the maximum power level (power "H") of step 2. If the power is not greater than the maximum power level (the "No" branch of block 1830), the process returns to block 1816 and begins another stage. However, if the power is greater than the maximum power level (the "Yes" branch of block 1830), at block 1832 the control circuitry can adjust or change the power slope to a second slope. In some examples, the second slope is slower than the first slope.

[0371] At block 1834, the control circuit can determine whether the applied power is greater than the maximum power level. If the power is not greater than the maximum power level (the "No" branch of block 1834), the process returns to block 1816 and begins another stage. However, if the power is greater than the maximum power level (the "Yes" branch of block 1834), at block 1836 the control circuit can change the power slope to the maximum power level setting, and then the process returns to block 1816 and begins another stage.

[0372] Referring back to decision block 1824, if the current impedance reading is not less than the minimum impedance Rmin (the "No" branch of block 1824), the control circuit can determine at block 1838 whether the current impedance reading is greater than the minimum impedance Rmin plus an impedance increment. If the current impedance reading is not greater than the minimum impedance Rmin plus the impedance increment (the "No" branch of block 1838), the control circuit can move to block 1828, and the method can continue as described above.

[0373] In some examples, rather than determining at step 1824 whether the measured current is less than a predetermined fraction of the maximum current, the control circuit 48 can determine whether the measured current is less than a predetermined fraction (or offset) of the current value measured at a predetermined time interval after the initiation of the pulse. For impedance monitoring systems, the control circuit 48 can determine whether the measured impedance is greater than a predetermined fraction (or offset) of the impedance value measured at a predetermined time interval after the initiation of the pulse.

[0374] However, if the current impedance reading is greater than the minimum impedance Rmin plus the impedance increment (the "Yes" branch of block 1838), the control circuit can move to decision block 1840. As a non-limiting example, the impedance increment can be 55 ohms, the current impedance reading can be 75 ohms, and the minimum impedance Rmin can be 15 ohms. In this non-limiting example, the current impedance reading (e.g., 75 ohms) is greater than the minimum impedance Rmin (e.g., 15 ohms) plus the impedance increment (e.g., 55 ohms) (the "Yes" branch of block 1838), the control circuit can move to decision block 1840.

[0375] As described above, the control circuit determines whether there is a set difference between the current impedance reading and the minimum impedance Rmin. If the difference is greater than the set amount, e.g., 55 ohms, the control circuit can now check how much energy has been delivered during the previous step 1 and the current step 2 phase at this point in time. At block 1840, the control circuit can determine whether the amount of energy (or charge) applied is less than an energy threshold (or charge threshold), e.g., 20 Joules (or 2 Coulombs of charge). If the amount of energy applied is not less than the energy threshold (the "No" branch of block 1840), the control circuit can reset the minimum impedance Rmin at block 1842 and return to step 1. Eventually, the system will return to the second dry period in step 2. In this way, if the amount of energy delivered exceeds the energy threshold, the control circuit can control the energy delivery of the therapy signal provided to the joined biological tissue during the second dry phase.

[0376] However, if the amount of energy applied (or the amount of charge applied) is less than the energy threshold (or the charge threshold) (the "Yes" branch of block 1840), the control circuit can end the pulse and proceed to Step 3, as shown in block 1844. In this way, if the amount of energy delivered is less than the threshold energy value, the control circuit can control the energy delivery of the treatment signal provided to the engaged biological tissue during the completion phase.

[0377] Step 3, which can be the completion phase, begins at block 1846 in FIG. 18B. At block 1846, the control circuit can store or record a target final impedance. In some examples, the target final impedance can be a set final number. In some examples, the target final impedance can be an incremental calculation from the lowest impedance value read or calculated in this step plus a predetermined percentage or incremental value. For example, if the minimum impedance Rmin for this step is measured to be 20 ohms, a predetermined incremental value of 280 ohms can be added to the final target impedance to set the value of the target final impedance to 300 ohms. In some examples, the target final impedance can be an incremental calculation from an impedance measurement taken after a predetermined time interval after the start of the pulse plus a predetermined percentage or incremental value. 250 ms

[0378] In some examples, the target final impedance can depend on the number of pulses (e.g., dry pulses). For example, if the endpoint depends on the number of pulses and if two pulses are delivered to the tissue, the final impedance value can be 320 ohms. However, if five pulses are delivered to the tissue, the final impedance can be 280 ohms. If the endpoint is not reached within a predetermined amount of time (e.g., 2 seconds), the method can return to Step 1 to attempt to further express fluid from the tissue and reach a satisfactory endpoint impedance.

[0379] At block 1848, the control circuit can reset and start a timer, for example, in response to the delivery of electrosurgical energy to the biological tissue (e.g., biological tissue positioned between two jaws of an electrosurgical device or in contact with one or more electrodes). If the predetermined impedance increment between the current impedance reading and the minimum impedance Rmin for this pulse is not met before the time interval is reached, the output returns to the first step because this can indicate that the tissue still contains too much water.

[0380] At block 1850, the control circuit can set the power output to a power level "I". In some examples, the control circuit can control the delivery of the therapeutic signal to the tissue using a constant power ramp. In some examples, the constant power ramp of Step 3 can be slower than the previous ramp, such as in Step 2. The control circuit can continue to deliver using the constant power ramp until a final impedance value is reached, for example, 320 ohms in a non-limiting example.

[0381] ​At block 1852, the control circuit can begin monitoring the impedance of the tissue. As described below, for example at blocks 1862 and 1872, the control circuit can compare the impedance representation of the biological tissue to a threshold, for example intermittently, and continue to deliver the electrosurgical energy until the threshold is met. At block 1854, the control circuit can increase the power to the constant power ramp "J". In some examples, prior to delivering the electrosurgical energy at the constant power ramp, the control circuit can deliver the electrosurgical energy at a constant power.

[0382] At block 1856, the control circuit can determine whether the power is greater than the step 3 maximum power level. If the power is greater than the step 3 maximum power level ("YES" branch of block 1856), at block 1858 in the method the control circuit can set the power to the step 3 maximum power level. After setting the power to the step 3 maximum power level at block 1858, or if the power is not greater than the step 3 maximum power level ("NO" branch of block 1856), at decision block 1860 the control circuit can compare the timer value to the time interval "R". 0.035 W / ms

[0383] If the timer value is not greater than or equal to the time interval "R" ("NO" branch of block 1860), the method can return to block 1854 and the control circuit can increase the power. However, if the timer value is greater than or equal to the time interval "R" ("YES" branch of block 1860), at block 1862 the control circuit can determine whether the impedance is greater than the minimum value within the pulse plus a predetermined delta impedance, where the predetermined delta impedance is the difference between the measured impedance and the lowest value of impedance measured in the pulse.

[0384] If the control circuit determines that the impedance is not greater than the target impedance minus the predetermined delta impedance ("NO" branch of block 1862), the method can return to step 1 as shown in block 1864. In this way, the control circuit can change the predetermined delta impedance value in response to the measured (e.g., intermittently measured) impedance and reduce or terminate energy delivery during the treatment phase.

[0385] However, if the control circuit determines that the impedance is greater than the target impedance minus the predetermined delta impedance ("YES" branch of block 1862), the method can move to block 1866 and increase the power to the power ramp "J".

[0386] At decision block 1868, the control circuit can determine whether the current power is greater than the maximum step 3 power level. If the current power is greater than the maximum step 3 power level ("YES" branch of block 1868), at block 1870 the control circuit can reset the power to the maximum step 3 power level "Q".

[0387] ​After setting the power to the step 3 maximum power level at block 1870, or if the power is not greater than the step 3 maximum power level (the "No" branch of block 1868), the control circuit can determine whether the impedance is greater than the target final impedance "P" at block 1872. If the control circuit determines that the impedance is greater than the target final impedance (the "Yes" branch of block 1872), the closure is complete at block 1874, and the control circuit can turn off the electrosurgical generator. However, if the control circuit determines that the impedance is not greater than the target final impedance (the "No" branch of block 1872), the control circuit can determine whether the timer is greater than the maximum step 3 output timer at block 1876.

[0388] If the timer is greater than the maximum step 3 output timer (the "Yes" branch of block 1876), the method can return to step 1 as shown at block 1878. For example, if the timer times out, this can indicate that the tissue was not sufficiently dried during the previous step. However, if the timer is not greater than the maximum step 3 output timer (the "No" branch of block 1876), the method can return to block 1866 to increase the power ramp.

[0389] In some examples, the timer at block 1860 can be used to detect a potential open circuit condition. For example, if the jaws of an electrosurgical device such as the forceps 14 are opened during the closure process, the electrosurgical generator can falsely determine that the accompanying impedance rise is the result of tissue drying. 0.05 W / ms

[0390] 0.035 W / ms Non-limiting values for the parameters A-S in Equation 2 are shown in Table 1 below:

[0391] Table 1:

[0392] A 10W B 0.035 W / ms D 320 ohms E 100 ms F 20 ohms H 60W I 15W J FIG. 2 P FIG. 2 Q 100W R FIG. 2 S FIG. 2

[0393] In accordance with this disclosure, the timer at block 1860 can be started during step 3. When the target final impedance (or threshold) is reached, the control circuit can record the elapsed time. If the target final impedance (or threshold) is reached within a very short time period, for example, before the threshold time limit, the control circuit can determine that an open circuit has occurred instead of a complete closure, and declare an error state. In other words, if the elapsed time is less than the time limit, the control circuit can declare an error state. The time limit can be 50 ms, 100 ms, or another time period.

[0394] ​For example, the control circuit can determine a difference between the minimum measured impedance Rmin and the current or maximum measured impedance, and compare the determined difference to a predetermined incremental impedance value. In some examples, the control circuit can increase the power ramp of the electrosurgical energy in response to the comparison. The control circuit can continue to increase the power ramp (e.g., at block 1854) until the determined difference meets or exceeds the predetermined incremental impedance value (e.g., at block 1862) or a power limit is reached (e.g., at block 1858).

[0395] However, in some examples, if the determined difference is equal to or greater than the predetermined incremental impedance value and the timer is greater than the threshold time limit, the control circuit can declare an error state and generate an error signal. In some examples, the open circuit error signal can cause the control circuit to communicate an error message to a user, for example, using the user interface 50 of the generator 10 and quickly terminate power to the electrosurgical device. FIG. 2

[0396] In some examples, the control circuit does not terminate power at the time stamp. Rather, power can continue until the final impedance is reached. At this point, the control circuit can evaluate the time interval to see if mitigation action is required. For example, the time interval or threshold can be set too long and produce a false negative, e.g., a good seal is formed but the system has determined that an open circuit exists, especially on thin tissue that seals quickly. The time interval or threshold can be set too short and produce a false positive, e.g., a good seal is not formed but the system does not detect an error, which can occur when, for example, the user is opening the jaws slowly.

[0397] Dwell time between pulses

[0398] It can be desirable to use a pulsed waveform to deliver the electrotreatment signal. With pulsing of the electrosurgical signal, the tissue between the device jaws can heat up. Without pulsing, the tissue can heat up and as the tissue passes through different temperature ranges, generally increasing with more and more energy applied, the fluid within the tissue can reach a boiling point. The boiling point can depend on the composition of the fluid being boiled and also on the pressure at which the jaws are clamping the tissue (changing the pressure changes the boiling point). This causes the generation of steam.

[0399] The steam that is generated can increase the tissue impedance, so less heating current flows through the tissue and more voltage is driven into the tissue. The steam bubble grows and because the steam changes phase as it evaporates, the volume of the bubble is now larger. This new larger volume further increases the impedance, so more voltage is needed to achieve the same power input. At the same time, the steam now moves from its previous location between the jaws and extends into the surrounding tissue.

[0400] ​The higher voltages required to power these steam pockets increase the adhesion of the tissue to the energy application surface (e.g., the jaws), while the outflow of steam from the application site into the surrounding tissue is negative (referred to as thermal margin). Thermal margin can damage structures not intended to be modified by the tissue, and can ultimately result in post-operative tissue necrosis and perforation of vital organs or organ structures. To overcome the propagation of steam pockets into surrounding tissue and the higher required drive voltages, the control method currently used is pulsing.

[0401] Pulsing refers to the presence of a pause in the application of energy delivered to the tissue with a level that can effect a change to the tissue. In some examples, the energy delivery is stopped for a period of time. In other examples, the energy level can be reduced to a level where the energy does not have a significant tissue effect. It can be desirable to apply at least some energy to the tissue rather than stopping delivery completely to allow continuous or near-instantaneous feedback of tissue state to the control circuitry.

[0402] In some approaches, a fixed period of 250 ms can be used as the pause period or "dwell time," which can ensure that the tissue steam pocket has substantially condensed before reapplying energy. The dwell time is the time interval after the first pulse and before the second pulse. If a dwell time less than 250 ms is used, the steam pocket can not be sufficiently depleted, and the subsequent application of energy can quickly restore the steam pocket.

[0403] While a pause shorter than 250 ms for the first pulse is generally correct, it is less clear for subsequent pulses. For the second pulse, a dwell time such as 200 ms can be appropriate, depending on the volume of tissue present between the jaws and its associated water content. Subsequent pulses can require even less time (e.g., the fifth pulse can require 50 ms or less) to allow recondensation of the now greatly reduced fluid content between the device jaws.

[0404] During these "dwell times," fluid can migrate back into the target tissue. During the dwell time, the generator can provide a low power signal to the tissue that is low enough not to trigger a tissue effect. Small reductions in tissue thickness are often the result of vessel occlusion, with the squeezed tissue containing fluid. Fluid can also be expelled by the steam with high pressure and pushing more mobile elements from the area between the device application plates, such as extracellular fluid.

[0405] Unfortunately, not all tissue has the same fluid level or tissue fluid mobility, and even the same amount of tissue thickness or width is not clamped between the device jaws for each occlusion. As such, a fixed standard for the pause period between pulses can not provide an effective or accurate pause time controller.

[0406] Furthermore, there can be a pressure to shorten the full activation as much as possible. Estimating long dwell times and applying them even to conservative choices that do not require such long times for the dwell period can unnecessarily prolong full activation. Unnecessary prolongation of full activation can lengthen the procedure time and can increase user fatigue, among other things.

[0407] To overcome the above-mentioned problems, the inventors have recognized that the control circuit can utilize known characteristics about the tissue between the jaws to accurately predict the most appropriate reduced pause period. For example, the control circuit can query a stored dataset (e.g., a lookup table) and using one or more known characteristics about the tissue can determine a reduced pause period or “dwell time.” The reduced dwell time can reduce the full activation time of the sealing cycle without impacting the low thermal margin and while still providing reliable sealing with high confidence.

[0408] In some examples, the control circuit (e.g., control circuit 48 of the surgical device 10 FIG. 2 may deliver first and second electrosurgical energy pulses to biological tissue in electrical communication with (e.g., physically engaged to, positioned between, or otherwise coupled to) two electrodes of a surgical device, where the first and second electrosurgical energy pulses are separated from each other by a respective dwell time. The control circuit can then determine a dwell time corresponding to at least one of the electrosurgical energy pulses following the first electrosurgical energy pulse.

[0409] In some examples, the control circuit (e.g., control circuit 48 of the surgical device 10 FIG. 23 may determine and use the amount of energy applied to the tissue to determine an optimized dwell time. The amount of fluid between the device jaws requires a certain amount of energy in order to boil at a known rate of energy application. The control circuit can estimate how much fluid is present by determining how much energy is delivered to the jaws to create a thermodynamic change in the tissue. The control circuit can use the determined amount of delivered energy to query a stored dataset to identify an appropriate corresponding dwell time. The control circuit can provide a longer dwell time for condensation for large vapor generation pulse cycles that use a large amount of energy and a shorter dwell time for condensation for smaller vapor generation pulse cycles that use a smaller amount of energy.

[0410] In other examples, the control circuit does not use a stored data set (e.g., a lookup table), but can determine the dwell time as a ratio of the determined energy applied to the jaws. In other examples, the control circuit can determine the dwell time as a multiple of the determined energy applied to the jaws. As a non-limiting example, if the energy applied to the jaws is 20 Joules, the wait time can be 200 ms (X*10 ms). Thus, 30 Joules can correspond to 300 ms. The formula X*10 is an example and not a limitation. It can also be part of a logarithmic scale or other mathematically based ratio term.

[0411] Additionally, the period of time required to boil the tissue between the jaws (at a set or known variable power) is another way to determine a dwell time that is long enough to ensure that sufficient condensation mechanisms have occurred before applying the next level of energy modification to the tissue. In some examples, the control circuit can attempt to turn off the power without boiling or with as little boiling as possible. If a longer period of time is required to boil the tissue as more energy is delivered to the tissue, the control circuit can determine that a longer dwell time is required. For example, the control circuit can start a timer when delivering a pulse, determine whether the tissue has boiled or is close to boiling, and if so, stop the timer, compare the timer to one or more values associated with respective dwell times, and determine or select a dwell time based on the comparison. The dwell time can be increased as the timer value increases. As a non-limiting example for purposes of illustration only, if it takes 30 Joules to boil or nearly boil the tissue, a dwell of 250 ms can be used, while if it takes 18 Joules to boil or nearly boil the tissue, a dwell of 150 ms can be used. These values can depend on the surface area of the jaws of the device being used or other factors.

[0412] While the energy applied to the tissue can be a strong indicator of the amount of steam produced, the impedance of the tissue can also affect the accuracy of the setting. For example, if the tissue has a higher electrical impedance (e.g., fat), more voltage and less current is required to boil the tissue, while if the tissue has good conductivity, the current does the work and a large steam pocket is produced with the same amount of energy. Thus, it is desirable for such a system to determine the dwell time using the energy application, thereby also determining and using the tissue impedance for the energy to produce the boiling effect.

[0413] The control circuit can use other electrical features to determine the dwell time, to check or refine the signal, including one or more of the following: current, reactance, inductance, impedance, resistance, power, phase angle, and energy.

[0414] Steam is a result of the current delivered, which excites molecules within the tissue and causes heating. When more current is needed to heat the tissue, it is an indication that more fluid resides within the tissue, given the understanding that the resistivity of the tissue structure itself is much higher than the fluid content. Thus, depending on the function of the electrotherapy signal, e.g., how the signal applies energy, the control circuit determines the peak current applied in the previous pulse, or the current delivered as a function of time, or the total amount of current delivered in the previous pulse. The control circuit uses the determined current and queries a stored data set, e.g., a lookup table, and determines or selects a dwell time based on the comparison.

[0415] For example, the control circuit (e.g., the control circuit 48 of the FIG. 23 ) can control and apply power to the tissue, where the current and voltage are allowed to float according to the tissue impedance (this is a simplification for general understanding). The control circuit can determine the total amount of current applied in the previous pulse, e.g., by integrating the amount of current delivered, which can help to understand how much steam can be generated during the energy application. Current (I) is equal to the rate of change of charge (Q) with respect to time (I = dQ / dt). Thus, the integral of the current I over a period of time is equal to the total amount of charge (Q) during that period of time.

[0416] Instead of using the total amount of energy delivered to the tissue, the inventors have determined that the total amount of charge delivered can be used to determine the dwell time. In some examples, the control circuit can determine the dwell time as a ratio of the total amount of charge or a multiple of the total amount of charge. In other examples, the control circuit can use the total amount of charge to determine the dwell time by using a stored data set, e.g., a lookup table, or by using some other mathematical derivation to provide an appropriate dwell time that does not need to be the same for all energy pulses.

[0417] The dwell time can be further refined by including other factors or exclusions as described above. An example of such an exclusion can be if current is delivered over a period of time greater than 300 ms, the control circuit can reduce the dwell time, as the amount of tissue within the jaws can have a significant impact. As such, the control circuit can start a timer, compare the timer to a threshold, e.g., 300 ms, and determine the dwell time based on the comparison. Alternatively, one or more feedback signals, e.g., phase angle, can be used to predict the composition of the tissue between the energy conducting elements. The control circuit can then take these feedback signals into account as an indication to determine an appropriate dwell time.

[0418] Incremental adjustment of control parameter as a function of monitored variable

[0419] The initial transition of collagen occurs at about 58 (±10) degrees Celsius (C), at which point the collagen fibers undergo a conformational change. The primary transition can occur at about 65 (±10) C, which corresponds to the gelation process of collagen in a water-containing environment and is caused by the breaking of internal crosslinks. Other important and significant temperature constraints tissue modification. At the general tissue temperature of between about 90 degrees Celsius to 100 degrees Celsius, additional phase changes begin to occur within the tissue, most notably the conversion of water to steam. This change is undesirable because steam is resistive, and while it will wrest energy away from the fluid to expel it from the tissue, it can also damage surrounding tissue via its migration into adjacent structures. This is undesirable because such damage can be uncontrolled and can affect tissue beyond the jaw footprint.

[0420] From a clinical standpoint, this means that when a surgeon is using the device and activating it near sensitive adjacent structures, care should be taken of any potential "thermal run-off." This is undesirable and can lead to unintended tissue damage, such as perforation and necrosis. Both of these can be immediate, or worse, occur many days after the application of energy.

[0421] Tissue containing steam also has a higher resistance than the same tissue with liquid water. This means that more energy is converted from current to voltage to drive the tissue state change. Because current is typically heated via molecular excitation, it is advantageous to limit the time of the vapor phase for good vessel sealing.

[0422] The present inventors have recognized the need for improved power control (or voltage control) techniques that seek to maintain the power output in a favorable state of collagen transition for a longer period of time before losing control and generating a bubble field. Using various techniques described in detail below, an electrosurgical generator (e.g., the electrosurgical generator 12 of FIG. 23 The electrosurgical generator 12 of the present disclosure can control the energy delivery of a treatment signal provided to biological tissue during a portion of a treatment phase as a function of incremental changes in energy delivery as a function of changes in measured electrical parameters of the biological tissue.

[0423] Applying energy to tissue can generate steam. As the amount of steam increases, the impedance increases. The increase in impedance can be an indication of steam generation. When the impedance increases, for the same amount of power delivered, the current decreases and the voltage increases (P = V*I). If the control circuit continues to apply the same amount of power after the control circuit determines that steam is being generated, the steam generation can undesirably increase and can adversely affect adjacent tissue. However, by using various techniques of the present disclosure, the control circuit can monitor changes in electrical parameters (e.g., current or impedance) and reduce the power, for example, to keep the tissue in a state where steam is just beginning to be generated but not being generated in large amounts, which can be desirable to affect collagen without undesirably creating a thermal margin.

[0424] The control circuit and measurement circuit (e.g. FIG. 2 The control circuit 48 and measurement circuit 46 of the generator 10 can monitor the current output of the generator and can convert an increase or decrease in current to a corresponding increase or decrease in output power. In some examples, the correlation between an increase in current or a decrease in current and subsequent control for increasing power or decreasing power can be directly proportional.

[0425] In some examples, the control circuit can adjust the power application to provide different power according to changes in the measured electrical parameter (e.g., current or impedance). The adjustment can be a function of the changes in the measured electrical parameter of the biological tissue. In some examples, the function can define a curve. In other examples, the function can be a linear equation, such as a linear transformation of the changes in the value of the measured electrical parameter (e.g., current or impedance) to changes in power or voltage (e.g., in watts or volts per second). The power (or voltage) can increase or decrease with changes in current. In some examples, the linear equation can be monotonic. In some examples, one or both of a minimum and a maximum can be defined, such that the control circuit can limit the changes in power or voltage.

[0426] FIG. 2 is a graph depicting an example of a relationship between changes in the value of a measured electrical parameter and changes in power. Although specifically depicted as changes in current per unit time versus changes in power per unit time in watts, the described techniques are not limited to current or power. In Aspects In the example shown, the y-axis of the graph 2100 can represent watts / second, and the x-axis can represent current change / second.

[0427] In examples, the linear equation defining the line 2102 can include an offset, such that the line does not pass through the origin, such that the change in power is positive when the change in current or incremental current value is zero. For example, in a graph 2100 of power change versus current change, the line 2102 can have a positive slope and can extend through quadrants I, II, and III. As another example, in a graph of voltage change versus current change, the line can have a negative slope and can extend through quadrants I, II, and IV. In Note In the example shown, one or both of a maximum slope 2104 and a minimum slope 2106 can be defined, such that the control circuit can limit the rate of change in power, for example.

[0428] In examples, the relationship between changes in the measured electrical parameter and incremental changes in energy can be stored in a dataset (e.g., a lookup table). The control circuit can query the stored dataset, compare the changes in the measured electrical parameter of the biological tissue to the stored dataset, and determine an incremental change in energy delivery based on the comparison.

[0429] Whether using a function such as a linear function or using a stored data set, the control circuit can monitor an electrical parameter such as a current change, such that the control circuit can make adjustments to a control parameter such as power or voltage in real-time (or "on-the-fly") to control the energy delivery of the treatment signal provided to the biological tissue during a portion of the treatment phase. In this way, the control circuit can control the electrical power or voltage of the treatment signal provided to the biological tissue according to changes in the measured electrical parameter of the biological tissue. For example, the control circuit can incrementally modify the electrical power or voltage according to the current increase.

[0430] As a non-limiting example, a small positive current rate change can result in a moderate power rate change. As another example, a zero current rate change can result in a negative power rate change. As another example, a negative current rate change can result in a high negative power rate change. As another example, a high current rate change can result in a high power rate change. By monitoring the current delta (also referred to as current change), different power controls can be applied, which can drive different tissue outcomes or be modified to accommodate different application devices.

[0431] As power is applied, the current can increase because the tissue has not yet boiled, and as the tissue is heated, the tissue becomes more conductive. Thus, more current is needed to increase the power. Using various techniques of the present disclosure, the control circuit (e.g., control circuit 48 of the ​ As power is applied, the current can increase because the tissue has not yet boiled, and as the tissue is heated, the tissue becomes more conductive. Thus, more current is needed to increase the power. Using various techniques of the present disclosure, the control circuit (e.g., control circuit 48 of the

[0432] As the amount of steam increases, the impedance increases. As the impedance increases, for the same amount of power delivered, the current decreases and the voltage increases (P = V*I). If the control circuit determines that steam is being generated, the control circuit can quickly reduce the power, but not so quickly that the generation of steam is stopped. As the impedance continues to increase, the control circuit can determine the amount of energy delivered according to the change in impedance. Using the determined amount of energy delivered, the control circuit can stop applying power and temporarily pause to allow the steam to collapse.

[0433] The biological tissue includes salt, and when energy is applied to the tissue, the sodium can burn. The burning sodium can become highly conductive, which can affect the accuracy of the measurements used to determine whether to increase or decrease the power or voltage. To avoid making real-time decisions based on small, rapid changes such as burning sodium, the electrosurgical generator (e.g., electrosurgical generator 10 of FIG. 1) can use a combination of techniques to determine whether to increase or decrease the power or voltage. ​The electrosurgical generator 12) can include or implement various filters. As an example, filters can be added to the current samples to smooth the generator output when considering changes in current delta. The frequency of filtering can depend on the processing speed of the generator control CPU.

[0434] In some examples, the control circuit can also determine whether a suggested power (or voltage) increase or decrease should occur. For example, the control circuit can sample recent increases or decreases in power (or voltage) and determine whether a continuing increase (or decrease) should continue, or whether the latest change in power ramp (or voltage ramp) is noise or within expected limits. For example, if the past two (or more) power ramp values (or voltage ramp values) were positive and large, but the latest value indicates a significant negative (decrease) in power, the control circuit can ignore the decision to decrease power (or voltage) until a subsequent current delta calculation is evaluated.

[0435] In some examples, the control circuit can include boundaries for maximum allowable change and / or maximum allowable output or ramp rate, preventing the generator from applying energy to tissue only by its hardware limits or too quickly. This can be accomplished by limiting the maximum power during the phase, limiting the maximum power change (e.g., limiting the maximum wattage ramp rate per second), etc.

[0436] These power (or voltage) control techniques can be used in single-ramp waveform outputs, or in pulsed waveform outputs that can control the energy delivery of a treatment signal provided to biological tissue during a portion of a treatment phase as a function of incremental changes in energy delivery as a function of measured changes in electrical parameters of the biological tissue. The pulsed waveform output has the advantage that power can be rapidly increased if needed. For example, power can be significantly reduced (or temporarily stopped) under certain conditions to allow steam to condense and to allow power to be reapplied in a ramping manner again until a desired tissue effect “end point” is reached.

[0437] ​

[0438] To further illustrate the above-described electrosurgical techniques, a non-limiting list of various aspects is described below. Each of the non-limiting aspects can exist independently, or can be combined with one or more of the other aspects in various permutations or combinations.

[0439] A. Short circuit error capture with band between trigger value and escape value

[0440] Aspect Al can include or use the following subject matter (e.g., a system, an apparatus, a method, an article, etc.), which can include or use a surgical system including: control circuitry; and output circuitry coupled to the control circuitry and configured to deliver electrosurgical energy to an output terminal for delivery to a patient, the output terminal configured to be coupled to an electrosurgical device having two electrodes, wherein the control circuitry is configured to: compare a first measured impedance value of biological tissue in electrical communication with the two electrodes of the electrosurgical device to a first threshold value; initiate a timer when the first measured impedance value is less than or equal to the first threshold value; compare a second measured impedance value of tissue between the two electrodes to a second threshold value, wherein the second threshold value is greater than the first threshold value; and continue to deliver the electrosurgical energy when the second measured impedance value is less than the second threshold value and the timer has not satisfied a time limit.

[0441] Aspect A2 can include or use, or can optionally be combined with at least some features of Aspect Al to include or use: the control circuitry is configured to: reduce the delivery of the electrosurgical energy when the second measured impedance value is less than the second threshold value and the timer has satisfied the time limit.

[0442] Aspect A3 can include or use, or can optionally be combined with at least some features of any one or more of Aspects Al or A2 to include or use: the control circuitry is configured to: generate an indication when the timer has satisfied the time limit.

[0443] Aspect A4 can include or use, or can optionally be combined with at least some features of any one or more of Aspects Al to A3 to include or use: the timer is less than 6 seconds.

[0444] Aspect A5 can include or use, or can optionally be combined with at least some features of any one or more of Aspects Al to A4 to include or use: the control circuitry is configured to adjust at least one of the first threshold value, the second threshold value, and the time limit based on at least one characteristic of the electrosurgical device or based on at least one characteristic of an electrosurgical generator configured to be coupled to the electrosurgical device.

[0445] Aspect A6 can include or use, or can optionally be combined with at least some features of any one or more of Aspects Al to A5 to include or use: the at least one characteristic includes a surface area of at least one electrode.

[0446] Aspect A7 can include or use, or can optionally be combined with at least some features of any one or more of Aspects A1 to A6 to include or use: the electrode is positioned on a jaw of the electrosurgical device, and wherein the at least one characteristic comprises: a jaw force of the electrosurgical device.

[0447] Aspect A8 can include or use, or can optionally be combined with at least some features of any one or more of Aspects A1 to A7 to include or use: the at least one characteristic comprises an output current of the electrosurgical generator.

[0448] Aspect A9 can include or use, or can optionally be combined with at least some features of any one or more of Aspects A1 to A8 to include or use: the electrode is positioned on a jaw of the electrosurgical device, and the biological tissue is positioned between the two electrodes of the electrosurgical device.

[0449] Aspect A10 can include or use a method of delivering electrical energy to an electrosurgical device, the method comprising: initiating a continuous delivery of electrosurgical energy to biological tissue in electrical communication with two electrodes of the electrosurgical device; comparing a first measured impedance value of the tissue to a first threshold value; initiating a timer when the first measured impedance value is less than or equal to the first threshold value; comparing a second measured impedance value of the tissue to a second threshold value, wherein the second threshold value is greater than the first threshold value; and continuing the delivery of the electrosurgical energy when the second measured impedance value is less than the second threshold value and the timer has not satisfied a time limit.

[0450] Aspect A11 can include or use, or can optionally be combined with at least some features of Aspect A10 to include or use: reducing the delivery of the electrosurgical energy when the second measured impedance value is less than the second threshold value and the timer has satisfied the time limit.

[0451] Aspect A12 can include or use, or can optionally be combined with at least some features of any one or more of Aspect A10 or Aspect A11 to include or use: generating an indication when the timer has satisfied the time limit.

[0452] Aspect A13 can include or use, or can optionally be combined with at least some features of any one or more of Aspects A10 to A12 to include or use: the electrode is positioned on a jaw of the electrosurgical device, and the biological tissue is positioned between the two electrodes of the electrosurgical device.

[0453] Aspect A14 can include or use, or can optionally be combined with at least some features of any one or more of Aspects A10 to A13 to include or use the timer being less than 6 seconds.

[0454] Aspect A15 can include or use, or can optionally be combined with at least some features of any one or more of Aspects A10 to A14 to include or use adjusting at least one of the first threshold, the second threshold, and the time limit based on at least one characteristic of the electrosurgical device or based on at least one characteristic of an electrosurgical generator configured to be coupled to the electrosurgical device.

[0455] Aspect A16 can include or use, or can optionally be combined with at least some features of any one or more of Aspects A10 to A15 to include or use the at least one characteristic of the electrosurgical device including a surface area of at least one electrode.

[0456] Aspect A17 can include or use, or can optionally be combined with at least some features of any one or more of Aspects A10 to A16 to include or use the electrode being positioned on a jaw of the electrosurgical device and the at least one characteristic of the electrosurgical device including a jaw force of the electrosurgical device.

[0457] Aspect A18 can include or use, or can optionally be combined with at least some features of any one or more of Aspects A10 to A17 to include or use the at least one characteristic of the electrosurgical generator including an output current of the electrosurgical generator.

[0458] B. Open circuit check of resistance limited end point RF waveform and evaluation of open circuit time in end phase

[0459] Aspect B1 can include or use a subject matter (e.g., a system, an apparatus, a method, an article of manufacture, etc.) that can include or use a surgical system comprising: a control circuit; and an output circuit coupled to the control circuit and configured to deliver electrosurgical energy to an output terminal for delivery to a patient, the output terminal configured to be coupled to an electrosurgical device having two jaws with respective electrodes, wherein the control circuit is configured to: initiate a timer in response to delivery of the electrosurgical energy to biological tissue in electrical communication with the two electrodes of the electrosurgical device; compare an impedance representation to a first threshold after the timer has satisfied a time limit; and continue delivery of the electrosurgical energy when the impedance representation is less than the first threshold.

[0460] Aspect B2 can include or use, or can optionally be combined with at least some features of Aspect B1 to include or use: the control circuit is configured to: reduce delivery of the electrosurgical energy when the impedance representation is greater than or equal to the first threshold and less than a second threshold.

[0461] Aspect B3 can include or use, or can optionally be combined with at least some features of Aspect B1 or B2 to include or use: the control circuit is configured to: reduce delivery of the electrosurgical energy when the impedance representation is greater than or equal to the second threshold.

[0462] Aspect B4 can include or use, or can optionally be combined with at least some features of any one or more of Aspects B1-B3 to include or use: the control circuit is configured to: generate an indication when the impedance representation is greater than or equal to the second threshold.

[0463] Aspect B5 can include or use, or can optionally be combined with at least some features of any one or more of Aspects B1-B4 to include or use: the control circuit is configured to generate the indication when the impedance representation is greater than or equal to the second threshold, the control circuit being configured to generate an audible indication.

[0464] Aspect B6 can include or use, or can optionally be combined with at least some features of any one or more of Aspects B1-B5 to include or use: the control circuit is configured to generate the indication when the impedance representation is greater than or equal to the second threshold, the control circuit being configured to generate a visual indication.

[0465] Aspect B7 can include or use, or can optionally be combined with at least some features of any one or more of Aspects B1 to B6 to include or use: the impedance representation comprises a value of the impedance.

[0466] Aspect B8 can include or use, or can optionally be combined with at least some features of any one or more of Aspects B1 to B7 to include or use: the impedance representation comprises a change in a value of the impedance.

[0467] Aspect B9 can include or use a subject matter (for example, a system, an apparatus, a method, an article of manufacture, etc.) that can include or use a surgical system comprising: control circuitry; and output circuitry coupled to the control circuitry and configured to deliver electrosurgical energy to an output terminal for delivery to a patient, the output terminal configured to be coupled to an electrosurgical device having two jaws with respective electrodes, wherein the control circuitry is configured to: initiate a timer in response to delivery of the electrosurgical energy to biological tissue in electrical communication with the two electrodes of the electrosurgical device; compare a rate of change of impedance of the biological tissue to a first threshold after the timer has satisfied a time limit; and continue delivery of the electrosurgical energy when the rate of change of the impedance is less than the first threshold.

[0468] Aspect B10 can include or use, or can optionally be combined with at least some features of Aspect B9 to include or use: the control circuitry is configured to: decrease the delivery of energy when the rate of change of the impedance is greater than or equal to the first threshold.

[0469] Aspect B11 can include or use, or can optionally be combined with at least some features of any one or more of Aspects B9 or B10 to include or use: the control circuitry is configured to: generate an indication when the rate of change of the impedance is greater than or equal to the first threshold.

[0470] Aspect B12 can include or use, or can optionally be combined with at least some features of any one or more of Aspects B9 to B11 to include or use: the control circuitry is configured to generate an indication when the rate of change of the impedance is greater than or equal to the first threshold, the control circuitry configured to generate the indication.

[0471] Aspect B13 can include or use subject matter (e.g., a system, a device, a method, an article of manufacture, etc.) that can include or use a method of delivering electrical energy to an electrosurgical device, the method comprising: starting a timer in response to delivery of electrosurgical energy to biological tissue in electrical communication with two electrodes of the electrosurgical device; comparing an impedance representation of the biological tissue to a threshold; continuing to deliver the electrosurgical energy until the threshold is met; recording an elapsed time when the threshold is reached; and declaring an error state if the elapsed time is less than a time limit.

[0472] Aspect B14 can include or use, or can optionally be combined with, at least some features of Aspect B13 to include or use: determining a difference between the first measured impedance and the second measured impedance and comparing the determined difference to a predetermined incremental impedance value; and generating an error signal in response to the determined difference being equal to or greater than the predetermined incremental impedance value and the timer being less than a threshold time limit.

[0473] Aspect B15 can include or use, or can optionally be combined with, at least some features of any one or more of Aspects B13 or B14 to include or use: determining a difference between the first measured impedance and the second measured impedance and comparing the determined difference to a predetermined incremental impedance value; and increasing a power ramp of the electrosurgical energy in response to the comparison.

[0474] Aspect B16 can include or use, or can optionally be combined with, at least some features of any one or more of Aspects B13-B15 to include or use: continuing to increase the power ramp until the determined difference meets or exceeds the predetermined incremental impedance value or a power limit is reached.

[0475] Aspect B17 can include or use, or can optionally be combined with, at least some features of any one or more of Aspects B13-B16 to include or use: the power ramp is a first power ramp, and in response to the power limit being reached, adjusting the power ramp from the first power ramp to a second power ramp, wherein the second power ramp is slower than the first ramp.

[0476] Aspect B18 can include or use, or can optionally be combined with at least some features of any one or more of Aspects B13 to B17 to include or use: the threshold is a first threshold, and during the completion phase: comparing the representation of impedance of the biological tissue to a second threshold; and delivering the electrosurgical energy at a constant power slope until the representation of impedance meets or exceeds the second threshold.

[0477] Aspect B19 can include or use, or can optionally be combined with at least some features of any one or more of Aspects B13 to B18 to include or use: delivering the electrosurgical energy at a constant power prior to delivering the electrosurgical energy at the constant power slope.

[0478] C. Alternating power correction output in low-precision hardware systems

[0479] Aspect C1 can include or use a subject matter (e.g., a system, an apparatus, a method, an article of manufacture, etc.) that can include or use a surgical system comprising: a control circuit; and an output circuit coupled to the control circuit and configured to deliver electrosurgical energy to an output terminal for delivery to a patient, the output terminal configured to be coupled to an electrosurgical device having two jaws with respective electrodes, wherein the control circuit is configured to: compare a representation of impedance of biological tissue in electrical communication with the two electrodes of the electrosurgical device to a first threshold; select a first power correction from at least two power corrections when the representation of impedance is within a first range; and apply the selected first power correction to a power setting of a power generator coupled to the electrosurgical device.

[0480] Aspect C2 can include or use, or can optionally be combined with at least some features of Aspect C1 to include or use: the control circuit is configured to select a second power correction from the at least two power corrections when the representation of impedance is within a second range.

[0481] Aspect C3 can include or use, or can optionally be combined with at least some features of any one or more of Aspects C1 or C2 to include or use: the control circuit is configured to compare a representation of at least one auxiliary parameter to at least one threshold; and select a third power correction from the at least two power corrections when the representation of the at least one auxiliary parameter is less than the at least one threshold.

[0482] Aspect C4 can include or use, or can optionally be combined with any one or more of Aspects C1 to C3 to include or use at least some of the features thereof, to include or use: the at least one secondary parameter includes one or more of an output current of the power generator, a tissue temperature, and a phase angle.

[0483] Aspect C5 can include or use, or can optionally be combined with any one or more of Aspects C1 to C4 to include or use at least some of the features thereof, to include or use: the control circuit is configured to deliver electrosurgical energy via the electrode of the electrosurgical device using the corrected power setting during the period of time.

[0484] Aspect C6 can include or use, or can optionally be combined with any one or more of Aspects C1 to C5 to include or use at least some of the features thereof, to include or use: the period of time is based at least on a range of impedance values.

[0485] Aspect C7 can include or use, or can optionally be combined with any one or more of Aspects C1 to C6 to include or use at least some of the features thereof, to include or use: the period of time is based at least on an amount of electrosurgical energy delivered.

[0486] Aspect C8 can include or use, or can optionally be combined with any one or more of Aspects C1 to C7 to include or use at least some of the features thereof, to include or use: the control circuit is configured to deliver electrosurgical energy via the electrode of the electrosurgical device using the corrected power setting; and to reduce application of the selected first power correction to the power setting when the representation of impedance meets or exceeds a second threshold.

[0487] Aspect C9 can include or use, or can optionally be combined with any one or more of Aspects C1 to C8 to include or use at least some of the features thereof, to include or use: the electrosurgical energy is delivered via the electrode of the electrosurgical device using the corrected power setting; and at least one of the upper and lower limits of the first range is dynamically adjusted when the representation of impedance is within a predetermined percentage or value of the upper or lower limit.

[0488] Aspect C10 can include or use subject matter (e.g., a system, apparatus, method, article of manufacture, etc.) that can include or use a method of delivering electrical energy to an electrosurgical device, the method comprising: comparing a representation of impedance of biological tissue in electrical communication with two electrodes of the electrosurgical device to a first threshold; selecting a first power correction from at least two power corrections when the representation of impedance is within a first range; and applying the selected first power correction to a power setting of a power generator coupled with the electrosurgical device.

[0489] Aspect C11 can include or use, or can optionally be combined with at least some features of Aspect C10 to include or use: selecting a second power correction from the at least two power corrections when the representation of impedance is within a second range.

[0490] Aspect C12 can include or use, or can optionally be combined with at least some features of any one or more of Aspects C10 or C11 to include or use: comparing a representation of at least one auxiliary parameter to at least one threshold; and selecting a third power correction from the at least two power corrections when the representation of the at least one auxiliary parameter is less than the at least one threshold.

[0491] Aspect C13 can include or use, or can optionally be combined with at least some features of any one or more of Aspects C10 to C12 to include or use: the at least one auxiliary parameter comprises one or more of an output current of the power generator, a tissue temperature, and a phase angle.

[0492] Aspect C14 can include or use, or can optionally be combined with at least some features of any one or more of Aspects C10 to C13 to include or use: delivering electrosurgical energy via the electrodes of the electrosurgical device during a period of time using the corrected power setting.

[0493] Aspect C15 can include or use, or can optionally be combined with at least some features of any one or more of Aspects C10 to C14 to include or use: the period of time is based at least on a range of the impedance value.

[0494] Aspect C16 can include or use, or can optionally be combined with at least some features of any one or more of Aspects C10 to C15 to include or use: the period of time is based at least on an amount of the electrosurgical energy delivered.

[0495] Aspect C17 can include or use, or can optionally be combined with at least some features of any one or more of Aspects C10 to C16 to include or use: delivering the electrosurgical energy via the electrode of the electrosurgical device using the corrected power setting; and reducing application of the selected first power correction to the power setting when the representation of the impedance meets or exceeds a second threshold.

[0496] Aspect C18 can include or use, or can optionally be combined with at least some features of any one or more of Aspects C10 to C17 to include or use: delivering the electrosurgical energy via the electrode of the electrosurgical device using the corrected power setting; and applying a second power correction to the power setting when the representation of the impedance is a specified percentage above an upper limit of a first range.

[0497] D. Reducing thermal margin combined energy devices

[0498] Aspect D1 can include or use a subject matter (e.g., a system, an apparatus, a method, an article of manufacture, etc.) that can include or use a combined ultrasonic energy and electrosurgical energy system, the system comprising: control circuitry; and output circuitry coupled to the control circuitry and configured to deliver energy to an output terminal for delivery to a patient, the output terminal configured to be coupled to an electrosurgical device having two jaws with respective electrodes, wherein the energy delivered comprises at least some ultrasonic energy, wherein the control circuitry is configured to: control delivery of the energy to biological tissue in electrical communication with the two electrodes of the electrosurgical device; measure a representation of a tissue parameter of the biological tissue; and reduce a level of the energy delivery or terminate the energy delivery based on a characteristic of the measured representation of the tissue parameter of the biological tissue, wherein the energy delivered is a combination of the electrosurgical energy and the ultrasonic energy, and wherein the control circuitry configured to reduce the level of the energy delivery or terminate the energy delivery is configured to: reduce a level of the ultrasonic energy.

[0499] Aspect D2 can include or use, or can optionally be combined with at least some features of Aspect D1 to include or use: the control circuitry configured to reduce the level of the ultrasonic energy is configured to: terminate delivery of the ultrasonic energy.

[0500] Aspect D3 can include or use, or can optionally be combined with at least some features of any one or more of Aspects D1 or D2 to include or use the control circuit configured to reduce the level of electrosurgical energy.

[0501] Aspect D4 can include or use, or can optionally be combined with at least some features of any one or more of Aspects D1-D3 to include or use the control circuit configured to reduce the level of electrosurgical energy is further configured to terminate delivery of the electrosurgical energy.

[0502] Aspect D5 can include or use, or can optionally be combined with at least some features of any one or more of Aspects D1-D4 to include or use the delivered energy is a combination of electrosurgical energy and ultrasonic energy, and the electrosurgical energy is power-controlled.

[0503] Aspect D6 can include or use, or can optionally be combined with at least some features of any one or more of Aspects D1-D5 to include or use the delivered energy is a combination of electrosurgical energy and ultrasonic energy, and the electrosurgical energy is voltage-controlled.

[0504] Aspect D7 can include or use, or can optionally be combined with at least some features of any one or more of Aspects D1-D6 to include or use the representation of the measured tissue parameter is an impedance value, and the control circuit is configured to compare the impedance value to a threshold value; and reduce the level of ultrasonic energy based on the comparison.

[0505] Aspect D8 can include or use, or can optionally be combined with at least some features of any one or more of Aspects D1-D7 to include or use the representation of the measured tissue parameter is a change in impedance, the method comprising: comparing the change in impedance to a threshold value; and reducing the level of ultrasonic energy based on the comparison.

[0506] Aspect D9 can include or use subject matter (e.g., a system, apparatus, method, article of manufacture, etc.) that can include or use a method of delivering energy to a combined ultrasonic energy and electrosurgical energy device, the method comprising: delivering energy to biological tissue in electrical communication with two electrodes of an electrosurgical device, wherein the delivered energy includes at least some ultrasonic energy; measuring a representation of a tissue parameter of the biological tissue; and reducing a level of delivery of the energy or terminating delivery of the energy based on a characteristic of the measured representation of the tissue parameter, wherein the delivered energy is a combination of electrosurgical energy and ultrasonic energy, and wherein reducing the level of delivery of the energy or terminating delivery of the energy includes reducing a level of the ultrasonic energy.

[0507] Aspect D10 can include or use, or can optionally be combined with at least some features of Aspect D9 to include or use: reducing the level of the ultrasonic energy includes terminating delivery of the ultrasonic energy.

[0508] Aspect D11 can include or use, or can optionally be combined with at least some features of any one or more of Aspects D9 or D10 to include or use reducing a level of the electrosurgical energy.

[0509] Aspect D12 can include or use, or can optionally be combined with at least some features of any one or more of Aspects D9-D11 to include or use: reducing the level of the electrosurgical energy includes terminating delivery of the electrosurgical energy.

[0510] Aspect D13 can include or use, or can optionally be combined with at least some features of any one or more of Aspects D9-D12 to include or use: the delivered energy is a combination of electrosurgical energy and ultrasonic energy, and the electrosurgical energy is power-controlled.

[0511] Aspect D14 can include or use, or can optionally be combined with at least some features of any one or more of Aspects D9-D13 to include or use: the delivered energy is a combination of electrosurgical energy and ultrasonic energy, and the electrosurgical energy is voltage-controlled.

[0512] Aspect D15 can include or use, or can optionally be combined with at least some features of any one or more of Aspects D9 to D14 to include or use: the representation of the measured tissue parameter is an impedance value, the method includes: comparing the impedance value to a threshold value; and reducing the level of the ultrasonic energy based on the comparison.

[0513] Aspect D16 can include or use, or can optionally be combined with at least some features of any one or more of Aspects D9 to D15 to include or use: the representation of the measured tissue parameter is a change in impedance, the method includes: comparing the change in impedance to a threshold value; and reducing the level of the ultrasonic energy based on the comparison.

[0514] E. Hierarchical resistance values for controlling thermal margin in systems with slow CPUs

[0515] Aspect El can include or use a subject matter (e.g., a system, an apparatus, a method, an article of manufacture, etc.) that can include or use a surgical system comprising: control circuitry; and output circuitry coupled to the control circuitry and configured to deliver energy to an output terminal for delivery to a patient, the output terminal configured to be coupled to electrosurgical equipment having at least one electrode, wherein the control circuitry is configured to: count electrosurgical energy pulses and deliver the electrosurgical energy pulses to biological tissue in communication with the at least one electrode; and for a plurality of electrosurgical energy pulses: compare a parameter to a threshold value; and adjust the threshold value based on the count of electrosurgical energy pulses.

[0516] Aspect E2 can include or use, or can optionally be combined with at least some features of Aspect El to include or use: the parameter is selected from the group consisting of: ...

Claims

1. A surgical system comprising: a control circuit; and an output circuit coupled to the control circuit and configured to deliver energy to an output terminal for delivery to a patient, the output terminal configured to be coupled to an electrosurgical device having two jaws with corresponding electrodes, wherein the control circuit is configured to: deliver a first therapeutic electrosurgical energy pulse to biological tissue in electrical communication with the two electrodes of the electrosurgical device, wherein the first therapeutic electrosurgical energy pulse is followed by a first dwell time; determine an amount of energy delivered to the jaws during the first therapeutic electrosurgical energy pulse; calculate a second dwell time based on the determined amount of energy delivered during the first therapeutic electrosurgical energy pulse, wherein the second dwell time is less than the first dwell time; and deliver a second therapeutic electrosurgical energy pulse to the biological tissue, wherein the second therapeutic electrosurgical energy pulse is followed by the second dwell time.

2. The surgical system of claim 1, wherein, the control circuit configured to determine the second dwell time is configured to: determine an electrical characteristic of the tissue; and calculate the second dwell time based on the determined amount of energy and the determined electrical characteristic.

3. The surgical system of claim 2, wherein, the determined electrical characteristic is impedance.

4. The surgical system of claim 2, wherein, the determined electrical characteristic is a phase angle.

5. The surgical system of claim 1, wherein, the control circuit configured to determine the second dwell time is configured to: start a timer upon delivery of a current of the first therapeutic electrosurgical energy pulse and stop the timer upon delivery of the current; compare the timer to one or more values; and determine the dwell time based on the comparison.

6. A surgical system comprising: a control circuit; and an output circuit coupled to the control circuit and configured to deliver energy to an output terminal for delivery to a patient, the output terminal configured to be coupled to an electrosurgical device having two jaws with corresponding electrodes, wherein the control circuit is configured to: deliver a first therapeutic electrosurgical energy pulse to biological tissue in electrical communication with the two electrodes of the electrosurgical device, wherein the first therapeutic electrosurgical energy pulse is followed by a first dwell time; start a timer upon delivery of the first therapeutic electrosurgical energy pulse; determine that the biological tissue has boiled and stop the timer upon determining that the biological tissue has boiled; compare the timer to one or more values; calculate a second dwell time based on the comparison, wherein the second dwell time is less than the first dwell time; and deliver a second therapeutic electrosurgical energy pulse to the biological tissue, wherein the second therapeutic electrosurgical energy pulse is followed by the second dwell time.

7. A surgical system comprising: a control circuit; and an output circuit coupled to the control circuit and configured to deliver energy to an output terminal for delivery to a patient, the output terminal configured to be coupled to an electrosurgical device having two jaws with corresponding electrodes, wherein the control circuit is configured to: delivering a first therapeutic electrosurgical energy pulse to biological tissue in electrical communication with two electrodes of the electrosurgical device, wherein the first therapeutic electrosurgical energy pulse is followed by a first dwell time; determining an amount of electrosurgical current delivered during the first therapeutic electrosurgical energy pulse; calculating a second dwell time based on the determined amount of electrosurgical current delivered during the first therapeutic electrosurgical energy pulse, wherein the second dwell time is less than the first dwell time; and delivering a second therapeutic electrosurgical energy pulse to the biological tissue, wherein the second therapeutic electrosurgical energy pulse is followed by the second dwell time.

8. The surgical system of claim 7, wherein, the control circuit is configured to: determine an amount of charge delivered during the first therapeutic electrosurgical energy pulse, wherein the control circuit configured to calculate the second dwell time based on the determined amount of electrosurgical current is configured to: calculate the second dwell time based on the determined amount of charge.

9. The surgical system of claim 7, wherein, The amount of electrosurgical current delivered during the first therapeutic electrosurgical energy pulse is a peak current.

10. The surgical system of claim 7, wherein, The amount of electrosurgical current delivered during the first therapeutic electrosurgical energy pulse is a current delivered as a function of time.

11. The surgical system of claim 7, wherein, The amount of electrosurgical current delivered during the first therapeutic electrosurgical energy pulse is a total current.

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