Patent Description:
There are available electrosurgical devices or instruments that use electrical energy to perform certain surgical tasks. Typically, electrosurgical instruments are surgical instruments such as graspers, scissors, tweezers, blades, and/or needles that include one or more electrodes that are configured to be supplied with electrical energy from an electrosurgical generator. The electrical energy can be used to coagulate, fuse, or cut tissue.

Electrosurgical instruments typically fall within two classifications: monopolar and bipolar. In monopolar instruments, electrical energy is supplied to one or more electrodes on the instrument with high current density while a separate return electrode is electrically coupled to a patient. The separate return electrode is often designed to minimize current density. Monopolar electrosurgical instruments can be useful in certain procedures but can include a risk of certain types of issues such as electrical bums that may be partially attributable to the functioning of the return electrode.

In bipolar electrosurgical instruments, one or more electrodes are electrically coupled to a source of electrical energy of a first polarity. In addition, one or more other electrodes are electrically coupled to a source of electrical energy of a second polarity opposite the first polarity. Bipolar electrosurgical instruments, which operate without separate return electrodes, can deliver electrical signals to a focused tissue area with reduced risks compared to monopolar electrosurgical instruments.

Even with the relatively focused surgical effects of bipolar electrosurgical instruments surgical, however, outcomes are often highly dependent on surgeon skill. For example, thermal tissue damage and necrosis can occur in instances where electrical energy is delivered for a relatively long duration or where a relatively high-powered electrical signal is delivered even for a short duration. The rate at which a tissue will achieve the desired fusing, sealing, or cutting effect upon the application of electrical energy varies based on the tissue type and can also vary based on pressure applied to the tissue by an electrosurgical device. However, it can be difficult for a surgeon to assess how quickly a mass of combined tissue types grasped in an electrosurgical instrument will be sealed a desirable amount.

Examples of electrosurgical systems employing electrosurgical generators in the same field as the present invention are disclosed in <CIT>, <CIT>, <CIT> and <CIT> and <CIT>.

The present invention provides an electrosurgical generator as recited in claim <NUM>.

The present invention will now be described, by way of example only with reference to the accompanying drawings in which the reference numerals designate like parts throughout the figures thereof.

Referring to both <FIG> and <FIG>, an exemplary electrosurgical system is illustrated. The electrosurgical system includes an electrosurgical generator <NUM> (as illustrated in <FIG>) in accordance with the present invention and a removably connectable electrosurgical instrument <NUM> (as illustrated in <FIG>). The electrosurgical instrument <NUM> can be electrically coupled to the electrosurgical generator <NUM> via a cabled connection <NUM> having an adaptor <NUM> configured to connect to a tool or device port <NUM> on the electrosurgical generator <NUM>. The electrosurgical instrument <NUM> may include audio, tactile and/or visual indicators to apprise a user of a particular predetermined status of the electrosurgical instrument <NUM> such as a start and/or end of a fusion or cut operation. In other embodiments, the electrosurgical instrument <NUM> can be reusable and/or connectable to another electrosurgical generator for another surgical procedure. A manual controller such as a hand or foot switch can be connectable to the electrosurgical generator <NUM> and/or electrosurgical instrument <NUM> to allow predetermined selective control of the electrosurgical instrument <NUM> such as to commence a fusion or cut operation.

In accordance with the present invention, the electrosurgical generator <NUM> is configured to generate radio frequency (RF) electrosurgical energy and it may receive data or information from the electrosurgical instrument <NUM> electrically coupled to the electrosurgical generator <NUM>. The electrosurgical generator <NUM>, in one embodiment, outputs RF energy (e.g., 375VA, 150V, 5A at <NUM>) and is configured to measure current and/or voltage of the RF energy and/or to calculate power of the RF energy or a phase angle or difference between RF output voltage and RF output current during activation or supply of the RF energy. The electrosurgical generator <NUM> regulates voltage, current and/or power and monitors the RF energy output (e.g., voltage, current, power and/or phase). The electrosurgical generator <NUM> stops the RF energy output under predefined conditions such as when a time value is met, and/or active phase angle, current, voltage or power and/or changes thereto is greater than, less than or equal to a stop value, threshold or condition and/or changes thereto.

As illustrated in <FIG>, the electrosurgical generator <NUM> comprises at least one advanced bipolar tool port <NUM>, a standard bipolar tool port <NUM>, and an electrical power port <NUM>. In other embodiments, electrosurgical units can comprise different numbers of ports. For example, in some embodiments, an electrosurgical generator <NUM> can comprise more or fewer than two advanced bipolar tool ports, more or fewer than the standard bipolar tool port, and more or fewer than the power port. In one embodiment, the electrosurgical generator <NUM> comprises only two advanced bipolar tool ports.

Each advanced bipolar tool port <NUM> is configured to be coupled to an advanced electrosurgical instrument having an attached or integrated memory module. The standard bipolar tool port <NUM> is configured to receive a non-specialized bipolar electrosurgical tool that differs from the advanced bipolar electrosurgical instrument connectable to the advanced bipolar tool port <NUM>. The electrical power port <NUM> is configured to receive or be connected to a direct current (DC) accessory device that differs from the non-specialized bipolar electrosurgical tool and the advanced electrosurgical instrument. The electrical power port <NUM> is configured to supply direct current voltage. For example, the electrical power port <NUM> can provide approximately <NUM> Volts DC. The electrical power port <NUM> can be configured to power a surgical accessory, such as a respirator, pump, light, or another surgical accessory. Thus, in addition to replacing the electrosurgical generator <NUM> for standard or non-specialized bipolar tools, the electrosurgical generator <NUM> can also replace a surgical accessory power supply. Replacing presently-existing generators and power supplies with the electrosurgical generator <NUM> can reduce the amount of storage space required on storage racks cards or shelves and reduce the number of main power cords required in a surgical workspace.

The electrosurgical generator <NUM> can comprise a display <NUM>. The display <NUM> can be configured to indicate the status of the electrosurgical system including, among other information, the status of the one or more electrosurgical instruments and/or accessories, connectors or connections thereto.

The electrosurgical generator <NUM> can comprise a user interface, such as a plurality of buttons <NUM>. The plurality of buttons <NUM> can allow user interaction (e.g., receiving user input) with the electrosurgical generator <NUM> such as, for example, requesting an increase or decrease in the electrical energy supplied to one or more electrosurgical instruments coupled to the electrosurgical generator <NUM>. The display <NUM> can be a touch screen display thus integrating data display and user interface functionalities. The electrosurgical tool or instrument <NUM> can further comprise of one or more memory modules. The memory may comprise operational data concerning the electrosurgical instrument and/or other instruments. For example, the operational data may include information regarding electrode configuration/reconfiguration, the electrosurgical instrument uses, operational time, voltage, power, phase and/or current settings, and/or particular operational states, conditions, scripts, processes or procedures. The electrosurgical generator <NUM> may be able to initiate reads and/or writes to the memory module.

The electrosurgical generator <NUM> can be provided with the capability to read the phase difference or phase angle between the voltage and current of the RF energy sent through the connected electrosurgical instrument <NUM> while RF energy is active. While tissue is being fused, phase readings are used to detect different states during the fuse or seal and cut process.

The electrosurgical generator <NUM> can monitor, measure or calculate current, power, impedance or phase of the RF output, but does not control current, power, impedance or phase. The electrosurgical generator <NUM> regulates voltage and can also adjust voltage. Electrosurgical power delivered is a function of applied voltage, current, and tissue impedance. The electrosurgical generator <NUM>, through the regulation of voltage, can affect the electrosurgical power, RF output, or energy being delivered. Power reactions are caused by the power interacting with the tissue or the state of the tissue without any control by a generator other than by the generator supplying power.

Once the electrosurgical generator <NUM> starts to deliver electrosurgical power, the electrosurgical generator <NUM> continues to do so continuously, e.g., for <NUM>, until a fault occurs or until a specific parameter is reached. In one example, the jaws of the electrosurgical instrument can be opened and thus compression relieved at any time before, during, and after the application of electrosurgical power. The electrosurgical generator <NUM>, in one embodiment, also does not pause or wait a particular duration or a predetermined time delay to commence termination of the electrosurgical energy.

With additional reference to <FIG>, a bipolar electrosurgical instrument <NUM> includes an actuator <NUM> coupled to an elongate rotatable shaft <NUM>. The elongate rotatable shaft <NUM> has a proximal end and a distal end defining a central longitudinal axis therebetween. At the distal end of the elongate rotatable shaft <NUM> are jaws <NUM> and at the proximal end is the actuator <NUM>. In one embodiment, the actuator <NUM> is a pistol-grip like handle.

The actuator <NUM> includes a movable handle <NUM> and a stationary handle or housing <NUM>. The movable handle <NUM> is coupled and movable relative to the stationary housing <NUM>. In accordance with various embodiments, the movable handle <NUM> is slidably and pivotally coupled to the stationary housing <NUM>. In operation, the movable handle <NUM> is manipulated by a user, e.g., a surgeon, to actuate the jaws, for example, selectively opening and closing the jaws <NUM>.

The actuator <NUM> includes a latch mechanism to maintain the movable handle <NUM> in a second position with respect to the stationary housing <NUM>. In various embodiments, the movable handle <NUM> comprises a latch arm which engages a matching latch contained within the stationary handle or housing <NUM> for holding the movable handle <NUM> at a second or closed position. The actuator <NUM> also comprises a wire harness that includes insulated individual electrical wires or leads contained within a single sheath. The wire harness can exit the stationary housing <NUM> at a lower surface thereof and form part of the cabled connection <NUM> (as illustrated in <FIG>). The wires within the harness can provide electrical communication between the electrosurgical instrument <NUM> and the electrosurgical generator <NUM> and/or accessories thereof.

A switch is connected to a user manipulated activation button <NUM> and is activated when the activation button <NUM> is depressed. In one aspect, once activated, the switch completes a circuit by electrically coupling at least two leads together. As such, an electrical path is then established from an electrosurgical generator <NUM> to the actuator <NUM> to supply RF energy to the electrosurgical instrument <NUM>. The electrosurgical instrument <NUM> comprises a translatable mechanical cutting blade that can be coupled to a blade actuator such as a blade lever or trigger <NUM> of the actuator <NUM>. The mechanical cutting blade is actuated by the blade trigger <NUM> to divide the tissue between the jaws <NUM>.

The actuator <NUM> includes an elongate rotatable shaft <NUM> assembly that includes a rotation knob <NUM> which is disposed on an outer cover tube of the elongate rotatable shaft <NUM>. The rotation knob <NUM> allows a surgeon to rotate the elongate rotatable shaft <NUM> of the electrosurgical instrument <NUM> while gripping the actuator <NUM>. The elongate rotatable shaft <NUM> comprises an actuation tube coupling the jaws <NUM> with the actuator <NUM>.

Attached to the distal end of the elongate rotatable shaft <NUM> are jaws <NUM> that comprise a first or upper jaw <NUM> and a second or lower jaw <NUM>. A jaw pivot pin pivotally couples the first jaw <NUM> and the second jaw <NUM> and allows the first jaw <NUM> to be movable and pivot relative to the second jaw <NUM>. One jaw is fixed with respect to the elongate rotatable shaft <NUM> such that the opposing jaw pivots with respect to the fixed jaw between an open and a closed position. Alternatively, both the first jaw <NUM> and the second jaw <NUM> can be pivotally coupled to the elongate rotatable shaft <NUM> such that both the first jaw <NUM> and the second jaw <NUM> can pivot with respect to each other.

The first or upper jaw <NUM> includes an electrode plate or pad. Similarly, the second or lower jaw <NUM> also includes an electrode plate or pad. The electrode of the first or upper jaw <NUM> and the electrode of the second or lower jaw <NUM> are electrically coupled to the electrosurgical generator <NUM> via wires and connectors to supply RF energy to tissue grasped between the electrodes of the first jaw <NUM> and the second jaw <NUM>. The electrodes, as such, are arranged to have opposing polarity and to transmit the RF energy therebetween. The first or upper jaw <NUM> in various embodiments also includes an upper jaw support with an assembly spacer positioned between the upper jaw support and the electrode. The first or upper jaw <NUM> also includes an overmold or is overmolded. The second or lower jaw <NUM> can also include a lower jaw support and the electrode. In the illustrated embodiment, the electrode is integrated or incorporated in the lower jaw support and thus the lower jaw support and the electrode form a monolithic structure and electrical connection. A blade channel extends longitudinally along the length of the first or upper jaw <NUM>, the second or lower jaw <NUM>, or both through which the blade operationally traverses. Surrounding a portion of the blade channel are one or more conductive posts. The conductive posts assist in immobilizing the tissue to be cut. The conductive posts also assist in ensuring the tissue being cut adjacent or proximate to the blade channel is fused as the conductive posts also participate in the transmission of RF energy to the tissue grasped between the jaws <NUM>. The second or lower jaw <NUM> can also include an overmold or is overmolded.

The electrodes have a generally planar sealing surface arranged to contact and compress tissue captured between the jaws <NUM>. The electrodes of the first or upper jaw <NUM> and second or lower jaw <NUM> have a seal surface in which the width of the seal surface is uniform, constant, or remains unchanged throughout.

The jaws <NUM> are curved to increase visualization and mobility of the jaws <NUM> at the targeted surgical site and during the surgical procedure. The jaws <NUM> have a proximal elongate portion that is denoted or aligned with straight lines and a curved distal portion denoting or defining a curve that is connected to the straight lines. The proximal most portion of the proximal elongate portion has or delimits a diameter that equals or does not exceed a maximum outer diameter of the jaws <NUM> or elongate rotatable shaft <NUM>. The jaws <NUM> have a maximum outer diameter in which the proximal most portion of the jaw <NUM> and the distal most portion of the jaws <NUM> remains within the maximum outer diameter. The curved distal potion has or delimits a diameter that is smaller than the maximum outer diameter and the diameter of the proximal most portion of the proximal elongate portion. The jaw <NUM> has a deeper inner curve cut-out than the outer curve and the tip of the jaws <NUM> are tapered for blunt dissection. The jaws <NUM> include a blade channel having an proximal elongate channel curving to a distal curved channel in which the proximal elongate channel is parallel and offset to the longitudinal axis of the elongate rotatable shaft <NUM> of the electrosurgical instrument <NUM>. As such, visibility and mobility at the jaws <NUM> are maintained or enhanced without increasing jaw dimensions that may further reduce the surgical working area or require larger access devices or incisions into the patient's body.

Electrode geometry of the conductive pads of the jaw assembly ensures that the sealing area or surface completely encloses the distal portion of the cutting path. The dimensions of the jaw surfaces are such that it is appropriately proportioned with regards to the optimal pressure applied to the tissue between the jaws <NUM> for the potential force the force mechanism can create. Its surface area is also electrically significant with regards to the surface area contacting the tissue. This proportion of the surface area and the thickness of the tissue have been optimized with respect to its relationship to the electrical relative properties of the tissue.

The second or lower jaw <NUM> and an associated conductive pad have an upper outer surface arranged to be in contact with tissue. The upper surfaces are angled or sloped and mirror images of each other with such positioning or orientation facilitating focused current densities and securement of tissue. The second or lower jaw <NUM> is made of stainless steel and is as rigid as or more rigid than the conductive pad. The second or lower jaw <NUM> comprises rigid insulators made of a non-conductive material and are as rigid as or more rigid than the second or lower jaw <NUM> or the conductive pad. Alternatively, the second or lower jaw <NUM> and the conductive pad are made of the same material.

In accordance with the present invention, the generator supplies RF energy and controls the supplied RF energy to seal or fuse tissue. At the beginning of a seal cycle, the generator is arranged to apply RF energy having a quickly increasing voltage. As such, the system provides RF energy having voltage that increases over a minimal time period resulting in the supplied RF energy with a voltage profile having a steep slope or change rate. The generator seeks to continue to increase voltage of the RF energy to identify or determine an RF output peak condition. In accordance with various embodiments, the RF output peak condition is denoted by a maximum current or power value resulting from the increasing voltage of the supplied RF energy. The generator seeks to increase voltage of the supplied RF energy up to and/or equal to this RF output peak condition. However, determining this RF output peak condition or point can vary based on tissue type and/or tissue volume in contact with the electrode or electrodes of the electrosurgical instrument. As such, the high voltage ramp or pulse provided by the system has a duration that is variable based on the tissue in contact with the instrument rather than a static, fixed, or predefined value, as exemplified in <FIG>. Similarly, electrode size and electrode contact relative to the tissue can further cause variations in this RF output peak condition. As such, determination of the RF output peak condition can be difficult.

With the system seeking to reach this varying RF output peak condition, the amount of time the system or electrosurgical generator supplies RF energy can also vary. For example, as shown in <FIG>, the peak conditions <NUM> occur at different times with tissue of different volumes. For example, tissue with smaller volumes may experience their respective peak conditions much earlier within a seal cycle compared to tissue that may have a much larger volume (e.g., as late as <NUM> into a seal cycle). As such, the peak condition in various embodiments generally happens later for thicker tissue, as thicker tissues may take longer to heat up. Furthermore, the height of the peak can be determined by the surface area of the tissue. Tissues with larger surface areas may have higher peak values due to having more tissue being or acting as electrically parallel resistance. However, the amount of time for quickly increasing the voltage of the RF energy being applied to the tissue is limited to a set maximum time threshold or limit and as a result avoids applying the RF energy longer than necessary. Setting a static time without seeking to reach the RF output peak condition however can lead to applying the RF energy longer than necessary, particularly for small tissue volumes. Furthermore, the use of static times can also present the situation where applying RF energy may not be long enough, particularly for large tissue volumes.

Accordingly, in accordance with the present invention, a generator providing a dynamic voltage ramp balances system performance on each end and allows for a close-to-ideal or optimal RF energy dosage initially or early and ultimately resulting in optimal tissue sealing. Rapidly achieving this RF output peak condition optimizes overall sealing of tissue and reduces time to seal without losing or reducing tissue integrity. In accordance with the present invention, the electrosurgical generator initially adjusts the voltage of the RF energy to be relatively high (e.g., <NUM>% or greater than the maximum voltage) and increases the voltage of the RF energy quickly (e.g., at a rate <NUM> volts per millisecond) to provide this dynamic voltage ramp or pulse to achieve the RF output peak condition.

Using a dynamic ramp ensures any tissue, regardless of volume, for example, is brought to the same RF output peak condition or water vaporization point quickly. As such, the likelihood of failing to reach or maintain the water vaporization point of the tissue (under-pulsing) is reduced. By reducing the likelihood of under-pulsing, the average RF delivery after the pulse can be shortened in time or lowered in power without affecting seal quality. Furthermore, the focus or attention of the system can be directed to removing water from the tissue efficiently, rather than variability associated with heating tissue.

As previously noted, determining when the RF output peak condition occurs is difficult, particularly in real-time. Noise or similar fluctuations or imprecision in measurement of the RF output may obscure or delay the determination of the RF output peak condition. Smoothing or filtering out such imprecisions, in various embodiments, can assist in enhancing detection or determination of the RF output peak condition. Delays in filter processing and the like may however also delay the determination of the RF output peak condition. Delays in identifying the determination of the RF output peak condition can cause the system to over-pulse the tissue.

To avoid or reduce this delay in identifying the RF output peak condition or a potential over-pulse of the tissue, the system can provide a break system. The break system utilizes a break value defined based on a predicted maximum value or window representing the RF output peak condition. The break value is as a percentage of the predicted maximum and/or a static threshold or gap, e.g., 400mA or 30W, below or within a predicted maximum value or window. The system monitors the RF output, e.g., the current and/or power, and the break system ensures that the monitored current and/or power reaches this break value before the voltage is adjusted, e.g., dropped, to ensure the RF output peak condition is quickly and accurately identified, thereby balancing both interests. It is however recognized that the lower or greater offset of the break value below the predicted maximum, the longer the specifically high voltage of the RF output is applied, e.g., over-pulse, but the less likely the system is to prematurely halt or drop the voltage of the RF output, e.g., under-pulse, due to for example triggering on noise.

The system may record or store a predicted maximum value and looks for the next monitored value to exceed the stored predicted maximum value. When this occurs, the monitored value is stored as the "new" maximum value. The system may monitor or record the RF output at set intervals, such as every <NUM>, and compares the interested value of the RF output against the stored predicted maximum value to determine if a new maximum has occurred.

The system may utilize a series of states with exit conditions set at regular intervals. As RF energy is applied and the value of interest changes, e.g., power and/or current increases, states are progressed through or cascaded. By increasing the number of states, the resolution of the cascade increase. However, depending on the resolution of the cascade, some accuracy can be lost in determining the RF output peak condition. A cascade or similar progression of states however is computationally less intensive and does not require or minimize the use of variables.

The break value or range may be calculated from a predicted maximum value by multiplying the predicted value by a percentage, e.g., <NUM>%. Higher predicted maximums could require a larger drop in the interested value (e.g., current or power) to trigger or to identify the RF output peak condition. A break value or range may be calculated from the predicted maximum value and subtracting a static offset (e.g., 400mA or 30W). Depending on the predicted maximum, this can be result in smaller or larger values than a percentage calculation but can be useful when the amplitude of noise or similar imprecision in the system is known, as the offset can be set to account for the imprecision (e.g., set higher than the amplitude of the noise). To ensure that a peak is detectable, the interested value (e.g., current or power) can be checked against the break value - in some scenarios the interested value (e.g., current or power) must reach at least the break value prior to any adjustments to the voltage to ensure that a peak can be identified. The system may provide a combination of the offset and percentage acting in parallel or serially and/or varying the order to enhance the identification or determination of the RF output peak condition to, for example, account for known imprecisions or when the predicted maximum value reaches a specific threshold where a larger drop in the interested value to trigger is not desired.

The system may monitor a rate of change of the interested value (e.g., current and/or power) to determine or to anticipate the RF output condition. As such, the system monitors the derivative or rate of the interested value and a change (e.g., a reduction in the change or rate) to identify the RF output peak condition or an indication that the RF output peak condition is near or close to occurring.

The system is arranged to adjust the current of the RF output to determine the RF output peak condition. In particular, the system, e.g., the RF amplifier of the generator, gradually ramps up current of the supplied RF energy and the generator is placed in current regulation. When a current regulation value exceeds the tissue's ability to take more current, the system will no longer be current regulated, resulting in a sharp increase in voltage as the system switches regulation. This voltage condition is thus used as an indication or determination of the RF output peak condition. As such, this system regulation can forgo the use of a predicted maximum value of interest being stored or utilized as provided in the percentage or offset systems or processes.

If errors or an unexpected result occurs, the system may terminate the process, e.g., the supplying of the RF energy. In various embodiments, such errors comprise a short detection error or open detection error. In one embodiment, a short detection error is determined by the electrosurgical generator when a measured phase angle of the supplied RF energy by the electrosurgical generator equals or exceeds a predetermined value, e.g., sixty degrees. In one embodiment, an open detection error is determined by the electrosurgical generator when a measured current of the supplied RF energy equals or is below a predetermined value, e.g., <NUM> milliamps, and/or a measured voltage of the supplied RF energy equals or exceeds a predetermined value, e.g., <NUM> volts. Completion of the control process without errors indicates a successful tissue seal. A successful tissue seal is recognized as the tissue seal being able to withstand a predetermined range of burst pressures or a specific threshold pressure.

It has been identified that tissue seal formation is dependent on denaturization and cross linkage of the native collagen present in vasculature extra cellular matrix which starts at about <NUM>. The strength of this matrix is highly dependent on desiccation (or removal of moisture) at the seal site via vaporization of the water present in the sealed tissue. Additionally, at a temperature of at least <NUM>, bonds between the denatured collagen and other living tissues can be created. Furthermore, that collagen degrades in response to duration under elevated temperature rather than the peak temperature of exposure. As such, exposing tissue to high temperature conditions (e.g., <NUM>) for the duration of a relatively short seal cycle does not impact the structure of the collagen but allows for the vaporization of water. The total time to seal tissue, in accordance with various embodiments, is reliant on heating the structure to the high temperature, e.g., <NUM>, to vaporize water such that the denatured collagen crosslinks and bonds to tissue and to limit collagen-water hydrogen bonding. To optimize seal time, it was therefore found to be desirable to achieve <NUM> within the grasped tissue as quickly as possible to begin the desiccation process.

As such, in accordance with the present invention, after RF energy has been initiated and/or various device checks are performed, the electrosurgical generator employs through the supplied RF energy a dynamic voltage ramp. Once the dynamic voltage ramp is complete, the system reduces the voltage to a predetermined level and slowly ramps up the voltage of the supplied RF energy. While the ramp occurs, sufficient amount of power is applied to the tissue to maintain a temperature sufficient for desiccation. This allows for continuous vaporization at a rate that does not cause seal structural failures and enhances vessel sealing performance.

The application of high voltage levels may cause the sealed tissue to adhere to the active electrodes. As such, termination of the voltage ramp at a lower peak voltage and holding that voltage output constant at the end allows for continued energy application while reducing the potential for tissue adherence to the active electrodes. Determination of when to terminate the voltage ramp, in accordance with various embodiments, is conducted by monitoring the phase and current of the supplied RF energy. As the tissue desiccates, the phase will become more capacitive and will draw less current. By terminating the voltage ramp at a fixed current value as it falls and when the phase is capacitive, the desiccation level of the tissue can be categorized. This variable voltage set point allows the seal cycle to adjust the energy application based on electrical and structural differences in tissues being sealed.

In various embodiments, in order to achieve the appropriate tissue effect, the phase angle, current, and/or power of the applied RF energy are measured, calculated, and/or monitored. <FIG> provide graphical representations of exemplary seal cycles in accordance with various embodiments. As illustrated in <FIG>, voltage 111a is shown relative to other RF output readings or indicators such as power 111b, impedance 111c, energy 111d, current 111e, and phase 111f. Additionally, although shown in <FIG>, in various embodiments, the electrosurgical generator can be configured to not measure or not calculate one or more of the indicators or readings (e.g., impedance) to reduce operational and power costs and consumptions, and/or reduce the number of parts of the electrosurgical generator. The additional information or readings are generally provided or shown for contextual purposes. Additionally, in various embodiments, impedance or temperature readings may not be used or may not be measured being that such readings may be imprecise or impractical.

As shown in <FIG>, the voltage of the RF output 111a is increased in the initial moments of the seal cycle and for a period relatively short compared to the total seal time to generate the voltage ramp or pulse of RF energy <NUM> (illustrated in <FIG>). The system seeks to determine or reach the RF output peak condition <NUM>. Subsequently after reaching the RF output peak condition <NUM>, the voltage of the RF energy is reduced and ramped up, slowly, relative to the voltage pulse. The slow voltage ramp <NUM> by the system seeks to maintain the tissue between the jaws close to at least <NUM> and thereby control the boiling rate of water in the tissue. In order to achieve the appropriate tissue effect of sealing the tissue, the phase angle, current, and power of the applied RF energy are monitored. Voltage of the RF energy is then held constant <NUM> to reduce the potential for tissue adherence. At seal completion (e.g., within a predetermined time frame or period according to the system), the RF energy supplied by the system is terminated or the RF energy supply is halted, disrupted, or stopped <NUM>. The voltage ramp of the RF energy is terminated and after a predefined time period according to the system, the RF energy supplied by the system is terminated or the RF energy supply is halted, disrupted, or stopped.

In various embodiments, the system identifies unintended current draw provided, for example, in some tissue bundles that draw the maximum current or power that can be supplied by the generator. While the system is under such a current condition, the supply of RF energy required to seal the tissue may not be sufficient or be efficiently supplied by the system. In various embodiments, to handle such a condition, the system determines if the current of the RF energy output is greater than <NUM>% of the allowable maximum current, e.g., 4500mA. If so, the system waits or delays further to ensure that the current has sufficiently dropped thereby indicating that sufficient desiccation of the tissue has occurred. If, after such a delay, the current has not sufficiently dropped, an error is indicated and/or the RF energy being supplied is halted. In accordance with various embodiments, the system determines or confirms that the current has sufficiently dropped if the current falls below a current threshold, e.g., 4100mA. As such, the system determines that the current condition has ceased and/or the tissue reached a vaporization or peak condition.

Referring now to <FIG>, in one embodiment, the electrosurgical generator <NUM> is connected to AC main input and a power supply <NUM> converts the AC voltage from the AC main input to DC voltages for powering various circuitry of the electrosurgical generator <NUM>. The power supply also supplies DC voltage to an RF amplifier <NUM> that generates RF energy. In one embodiment, the RF amplifier <NUM> converts 100VDC from the power supply to a sinusoidal waveform with a frequency of <NUM> which is delivered through a connected electrosurgical instrument or tool <NUM>. RF sense circuitry <NUM> measures/calculates voltage, current, power, and phase at the output of the electrosurgical generator <NUM> in which RF energy is supplied to the connected electrosurgical instrument or tool <NUM>. The measured/calculated information is supplied to a controller <NUM>.

In one embodiment, the RF sense <NUM> analyzes the measured AC voltage and current from the RF amplifier <NUM> and generates DC signals for control signals including voltage, current, power, and phase that are sent to the controller <NUM> for further processing. In one embodiment, RF sense <NUM> measures the output voltage and current and calculates the root means square (RMS) of the voltage and current, apparent power of the RF output energy, and the phase angle between the voltage and current of the RF energy being supplied through the connected electrosurgical instrument or tool <NUM>. In particular, the voltage and current of the output RF energy are processed by analog circuitry of the RF sense to generate real and imaginary components of both voltage and current. These signals are processed by a field-programmable gate array (FPGA) to give different measurements relating to voltage and current, including the RMS measurements of the AC signals, phase shift between voltage and current, and power. Accordingly, in one embodiment, the output voltage and current are measured in analog, converted to digital, processed by an FPGA to calculate RMS voltage and current, apparent power and phase angle between voltage and current, and then are converted back to analog for the controller <NUM>.

In one embodiment, controller <NUM> controls or signals the RF amplifier <NUM> to affect the output RF energy. For example, the controller <NUM> utilizes the information provided by the RF sense <NUM> to determine if RF energy should be outputted, adjusted or terminated. In one embodiment, the controller <NUM> determines if or when a predetermined current, power, and/or phase threshold has been reached or exceeded to determine when to terminate the output of RF energy. In various embodiments, the controller <NUM> performs a fusion or sealing process described in greater detail herein and in some embodiments the controller <NUM> receives the instructions, settings, or script data to perform the sealing process from data transmitted from the electrosurgical instrument or tool <NUM>.

The RF Amplifier <NUM> generates high power RF energy to be passed through a connected electrosurgical instrument or tool <NUM>. In one example, the electrosurgical instrument or tool <NUM> is used for fusing or sealing tissue. The RF Amplifier <NUM> in accordance with various embodiments is configured to convert a 100VDC power source to a high power sinusoidal waveform with a frequency of <NUM>. The converted power is then delivered to the connected electrosurgical instrument or tool <NUM>. The RF Sense <NUM> interprets the measured AC voltage and current from the RF amplifier <NUM> and generates DC control signals, including voltage, current, power, and phase, that is interpreted by the controller <NUM>.

The electrosurgical generator <NUM> (which includes the controller <NUM> and/or the RF sense <NUM>) monitors and/or measures the RF energy being supplied to determine if it is as expected. In various embodiments, the system (e.g., the controller and/or RF sense), monitors the voltage and/or current of the RF energy to ensure the voltage and the current are above predefined threshold values. The system (e.g., the controller and/or RF sense), also monitors, measures, and/or calculates the phase and/or power of the supplied RF energy. The system (e.g., the controller and/or RF sense) ensures that the voltage, current, phase, and/or power of the supplied RF energy is within a predefined voltage, current, phase, and/or power window or range. In one embodiment, the voltage, current, phase, and/or power window are respectively delimited by a predefined maximum voltage, current, phase, and/or power and a predefined minimum voltage, current, phase, and/or power. If the voltage, current, phase, and/or power of the RF energy moves out of its respective window, an error is indicated. In one embodiment, the respective window slides or is adjusted by the system as RF energy is being supplied to seal the tissue between the jaws of the instrument. The adjustment of the respective window is to ensure that supplied RF energy is as expected. The system, in various embodiments, monitors the phase, and/or current or rate of phase, and/or current of the supplied RF energy to determine if the phase and/or current has reached or crossed a predefined phase and/or current threshold. If the phase and/or current crossing has occurred with respect to the predefined phase and/or current threshold, then the RF energy is supplied for a predefined time period before terminating.

In accordance with various embodiments, an operations engine of controller <NUM> enables the electrosurgical generator <NUM> to be configurable to accommodate different operational scenarios including but not limited to different and numerous electrosurgical instruments or tools, surgical procedures, and preferences. The operations engine receives and interprets data from an external source to specifically configure operation of the electrosurgical generator <NUM> based on the received data.

In accordance with various embodiments, the operations engine may receive configuration data from a database script file that is read from a memory device of the electrosurgical tool or instrument <NUM>. The database script file defines the state logic used by the electrosurgical generator <NUM>. Based on the state determined and measurements made by the electrosurgical generator <NUM>, the database script file can define or set output levels as well as shutoff criteria for the electrosurgical generator <NUM>. The database script file, in one embodiment, includes trigger events that include indications of a short condition, for example, when a measured phase is greater than <NUM> degrees, or an open condition, for example, when a measured current is less than <NUM> mA.

In accordance with various embodiments, after the dynamic voltage ramp, tissue that draws a relatively low amount of current or power is small in volume or may be already highly desiccated as shown, for example, in <FIG>. The highly desiccated tissue can be commonly encountered in a double or repeated seal situation (e.g., when a surgeon activates the instrument to supply RF energy a second time after a first seal cycle or an already completed seal cycle without moving the instrument or positioning the instrument on different portions of the tissue or an entirely different tissue). Double or repeated seals results in an additional application of RF energy including heat and thereby increases potential eschar buildup, thermal spread, and/or adhesion. In various embodiments, the system reduces or prevents RF output with a high voltage when such repeated seals occur.

In accordance with various embodiments, the system identifies or determines a tissue's desiccation level in contact with the instrument. The system employs low levels of current or power, high levels of impedance, low phase angles, low energy delivery, and/or a lack of water vaporization (e.g., steam) during the seal cycle to identify a tissue's desiccation level. Once the desiccation level of the tissue has been identified, the RF output is reduced, such as providing RF energy for a limited time period or power level. In various embodiments, static thresholds can be used for any of these values to trigger conditions (e.g., 500mA) and/or thresholds can be calculated during the seal cycle (e.g., <NUM>% below a predicted maximum).

In various embodiments, the system uses one or more of these threshold values to distinguish already-sealed tissue and triggers early in the seal cycle. At the end of the seal cycle, first activations and subsequent activations can look very similar with the tissue being desiccated in both cases. However, at the beginning of the seal cycle, first activations will draw much more current or power since water is still present in the tissue (compared to subsequent seals which may not). In addition, as tissue seals, the current or power drawn can change substantially. An activation on an already-sealed tissue may have a much lower rate of change and as such, the system utilizes the derivative of measurement value of interest to be used to identify a meaningful change being made to the tissue.

In various embodiments, the system tracks phase of the RF output and in particular, at the beginning of a seal cycle, to identify repetitive seals and/or thin tissue. Double seals tend to have phase values of greater than <NUM> degrees. Once a repeated seal or piece of thin tissue is identified, an alternate RF path for that tissue can be applied.

In various embodiments, the system uses a cascade of phase values which adjusts the RF output depending on the magnitude of the initial phase. For example, if the phase is between <NUM> and <NUM> degrees, a modest reduction of RF energy is applied. However, if the phase is between <NUM> and <NUM> degrees, there is more certainty of the type of tissue in contact with the instrument, and thus RF energy being applied is reduced further or more aggressively. Continuing with this example, a phase angle over <NUM> degrees would provide the largest or most aggressive reduction in RF energy.

Once highly desiccated or thin tissue has been identified, any change in RF output that results in less heat being applied results in a better tissue sealing effects. Additional RF energy or no reduction in RF energy on this type of tissue can result in additional thermal spread, eschar, adhesion, and/or a longer procedure time without providing further benefits to hemostasis.

Exemplary RF energy control process, script, or systems for the electrosurgical generator and associated electrosurgical tools for fusing or sealing tissue are shown in <FIG>. In a first step <NUM>, RF energy is supplied by the electrosurgical generator through the connected electrosurgical tool. The electrosurgical generator sets the voltage of the supplied RF energy in order to generate the RF energy having a steep ramp in step <NUM>. In accordance with various embodiments, the RF energy that is provided or generated is a steep ramp with voltage increasing from a predefined initial value (e.g., 40V) to a maximum value (e.g., 60V) in a predefined time period (e.g., <NUM>) and/or with current increasing from a predefined initial value (e.g., 2500mA) to a predefined maximum value (e.g., 5000mA) in the same predefined time period (e.g., <NUM>). The electrosurgical generator or system determines or identifies an RF output peak condition in step <NUM> while continuing to supply RF energy in the ramping fashion performed in step <NUM>.

In various embodiments, the system monitors or measures the current and/or power of the RF output in order to determine if the current and/or power is decreasing or has reached a predefined threshold. This is performed in order to further determine if a peak condition has been reached. If a peak condition is not identified or reached, the system determines if a double seal condition is present in step <NUM>. In various embodiments, the system monitors or measures the current of the RF output and determines if the current is decreasing or has reached a predefined current threshold to determine if a double seal condition is present or identified. If the peak condition and/or a double or repeated seal is identified, the system alters or adjust to reduce the voltage of the RF output in step <NUM>. In various embodiments, the system causes the RF energy to ramp gradually (in step <NUM>), increasing from a predefined initial value (e.g., 35V) to a maximum value (e.g., 45V) over a predefined time period (e.g., <NUM>).

The electrosurgical generator or system monitors, determines, or identifies a hold condition in step <NUM> while continuing to supply RF energy in the ramping fashion as described in step <NUM> (above). The electrosurgical generator or system measures, calculates, and/or monitors at least the phase, voltage, current, power, and/or change/rate thereof of the supplied RF energy. If the condition (e.g., a phase and current condition) is reached or equals, exceeds or falls below a predetermined threshold or value in step <NUM>, the RF output is adjusted in step <NUM>. The electrosurgical generator causes the ramp to be terminated. If a phase condition or threshold is reached or falls below a predetermined phase threshold value and a current condition or value is reached or falls below a predetermined current threshold value, the electrosurgical generator adjusts the voltage of the supplied RF energy to be constant. If the phase and current condition or threshold is not reached or crossed, the electrosurgical generator waits a predefined time period while continuing to supply RF energy in the ramping fashion (via step <NUM>) and monitoring for the hold condition (via step <NUM>). With constant voltage (via step <NUM>), the electrosurgical generator monitors, identifies, or determines an end condition (via step <NUM>) while continuing to supply and/or adjust the RF energy being supplied (in step <NUM>). If the end condition is determined or identified, the process is characterized as being done. Termination procedures are initiated and/or RF energy supplied by the generator is stopped (in step <NUM>). If the power condition or threshold representing the end condition is reached or equals, exceeds or falls below a predetermined threshold or value, the process is characterized as being done. Termination procedures can then be initiated and/or RF energy supplied by the generator can be stopped. If the end condition or threshold is not reached or crossed, the electrosurgical generator continues to supply RF energy, while monitoring for the power condition.

In various embodiments, prior to the start of the process, impedance is measured to determine a short condition or open condition through a low voltage measurement signal delivered to a connected electrosurgical tool. In one embodiment, passive impedance is measured to determine if the tissue grasped is within the operating range of the electrosurgical tool (e.g., <NUM>-200Ω). If the initial impedance check is passed, the RF energy is supplied to the electrosurgical tool, after which impedance/resistance is not measured again or ignored.

In various embodiments, the maximum current or power value is static or predetermined, stored in memory, or is provided or set through external inputs. In accordance with various embodiments, the maximum current or power value is determined by the system through the application of the RF energy and monitoring the current and/or power of the supplied RF energy to determine a current or power peak. In various embodiments, the maximum current or power value represents a vaporization point for the tissue in contact with the electrosurgical instrument. In various embodiments, the generator provides a high voltage steep ramp to bring the tissue to a water vaporization point quickly.

In accordance with various embodiments, a maximum phase value is determined by the system through the application of the RF energy and monitoring the phase to determine a phase peak representing an RF output peak condition. In various embodiments, a thermocouple or similar temperature sensor or detection system is provided with the instrument, such as a thermocouple embedded on the surface of a jaw, to monitor tissue temperature and potentially identify a rapid rise of temperature occurring until water vaporization begins, at which point a state change would stop the rise in temperature due to additional heat creating steam and thus an RF output peak condition can be identified. In accordance with various embodiments, a minimum impedance is determined by the system through the application of the RF energy and monitoring the tissue impedance to determine an impedance floor representing an RF output peak floor. As such, the process or system is somewhat inverted with a minimum value or window being determined rather than a maximum.

The electrosurgical generator provides a high voltage ramp or pulse to bring the tissue to a RF output peak point or condition quickly. In various embodiments, the RF output peak condition represents or corresponds to a water vaporization point or condition, e.g., when the fluid in the tissue begins to change state and vaporize. This can be observed when steam starts being generated from the tissue being sealed. This point or condition is defined or identified when the power or current output of the RF energy being applied or supplied is at its greatest or reaches its peak. If the vaporization or peak point is not reached during the pulse (e.g., under-pulsing), then the subsequent drop in voltage and gradual ramp-up is delayed in this seal cycle. Tissue that is under-pulsed starts its effective seal cycle or removal of water much later than anticipated, resulting in less total water being removed in the same time period.

In accordance with various embodiments, the electrosurgical generator is configured to provide additional regulation of various parameters or functions related to the output of the RF energy, voltage, current, power, and/or phase and the operations engine is configured to utilize the various parameters or functions to adjust the output of the RF energy. In one exemplary embodiment, the control circuitry provides additional regulation controls for direct regulation of phase in which voltage, current, and/or power output would be adjusted to satisfy specified phase regulation set points provided by the operations engine.

In accordance with various embodiments, the generator utilizes the monitored, measured and/or calculated values of voltage, power, current, and/or phase (e.g., control indicators) to recognize and act/perform operation conditions. In various embodiments, additional measurements or calculations based on the measured values related to RF output regulation circuitry are provided by the script or operations engine to recognize and act upon additional or different events related to or trigger by the additional measurements or calculations relative to other measurements or thresholds. The additional measurements in one embodiment include error signals in combination with a pulse width modulation (PWM) duty cycle used to regulate the output of voltage, current and/or power or other similar regulation parameters. Different or additional events or indicators that could be identified and triggered in various embodiments could be transitions from one regulation control to another regulation control (e.g., current regulation to power regulation). In various embodiments, subsequent impedance or temperature checks or measurements may not be performed as such checks or measurements may be imprecise and/or impractical.

In various embodiments, the generator utilizes many states, control points, or checks to identify a phase, current, or power value and respectively for a positive or negative trend. An error is signaled if the electrosurgical generator does not identify an expected trend. The multistate checks increase or enhance the electrosurgical generator resolution in identifying an expected RF output trend over different types of tissue.

In various embodiments, the electrosurgical generator also monitors the phase or current and/or rate of phase or current to determine if the connected electrosurgical tool has experienced an electrical open condition or short condition. In one example, the electrosurgical generator identifies an electrical short condition of the connected electrosurgical instrument by monitoring the phase of the applied or supplied RF energy. If the monitored phase is greater than a predefined maximum phase value, an electrical short condition is identified. Similarly, in one example, the electrosurgical generator identifies an electrical open condition of the connected electrosurgical instrument by monitoring the current of the applied or supplied RF energy. If the monitored current is less than a predefined minimum current, an electrical open condition is identified. In either or both cases, the electrosurgical generator upon discovery of the open condition and/or short condition indicates an error and the RF energy being supplied is halted.

In various embodiments, the predefined process as described throughout the application is loaded into a memory module embedded into a connector removably connected to a plug and/or cable connection to an electrosurgical instrument. In various embodiments, the device script or process is programmed onto an adapter PCBA (Printed Circuit Board Assembly) contained within the device connector or hardwired into circuitry within the device connector or controller during manufacture/assembly. The script source file is written in a custom text-based language and is then compiled by a script compiler into a script database file that is only readable by the generator. The script file contains parameters specifically chosen to configure the generator to output a specific voltage (e.g., 100v (RMS)), current (e.g., 5000mA (RMS)), and power level (e.g., 300VA). In various embodiments, a device key programmer device reads and then programs the script database file into the memory of the adapter PCBA.

Turning now to some of the operational aspects of the electrosurgical tool or instrument described herein in accordance with various embodiments, once a vessel or tissue bundle has been identified for fusing, the first jaw <NUM> and the second jaw <NUM> are placed around the tissue. The movable handle <NUM> is squeezed and thereby pivots the first jaw <NUM> and the second jaw <NUM> together to effectively grasp the tissue. The actuator <NUM> has a first or initial position in which the jaws <NUM> are in an open position with the movable handle <NUM> positioned away or spaced from the stationary housing <NUM>.

The depression of the activation button <NUM> by the surgeon causes the application of the radio frequency energy to the tissue between the jaws <NUM>. Once the tissue has been fused, the actuator <NUM> can be reopened by the movable handle <NUM> being released and moved away from stationary housing <NUM>. To cut tissue between the jaws <NUM>, the user can actuate the blade trigger <NUM>. When the blade trigger is moved proximally, a cutting blade moves distally to divide the tissue between the jaws <NUM>. When the surgeon releases the blade trigger <NUM>, the blade spring resets the cutting blade to its original position. In accordance with various embodiments, the actuator <NUM> has a cut position in which the jaws <NUM> are in a closed position, the movable handle <NUM> is closed and latched and the blade trigger <NUM> has been depressed advancing the cutting blade to its distal most position.

In various embodiments, an intermediate or unlatched position is provided in which the jaws <NUM> are in a closed or proximate position but the movable handle <NUM> is unlatched. As such, if the movable handle <NUM> is released, the movable handle <NUM> will return to its original or initial position. In one embodiment, the blade trigger <NUM> may not be activated to cut tissue between the jaws <NUM> but the activation button or switch <NUM> may be activated to fuse tissue between the jaws <NUM>. In various embodiments, a latched position is provided in which the jaws <NUM> are in a closed or proximate position and the movable handle <NUM> is latched. As such, if the movable handle <NUM> is released, the movable handle <NUM> will not return to its original or initial position. In one embodiment, the activation button or switch <NUM> may be activated to fuse tissue between the closed jaws <NUM> and/or the blade trigger <NUM> may be activated to cut tissue between the jaws <NUM>.

As described, in accordance with various embodiments, the electrosurgical instrument has a first (open) state in which the jaws <NUM> are spaced from each other and thus the movable handle <NUM> is also spaced from the stationary housing <NUM>. The electrosurgical instrument is thus positioned to grasp tissue between the jaws <NUM>. In the second (intermediate) state of the instrument, the jaws <NUM> are proximate to each other to grasp tissue between the jaws <NUM> and likewise the movable handle <NUM> and the stationary housing <NUM> are proximate to each other. The surgeon can revert back from the second state to the first state by opening the jaws <NUM> and thus positioning the jaws <NUM> again to grasp the tissue or other tissue. In the third (closed) state of the electrosurgical instrument, the movable handle <NUM> is moved further closer to the stationary housing <NUM>. In some embodiments, the movable handle <NUM> may latch to the stationary housing <NUM>. Movement to the third state, tissue grasped between the jaws <NUM> can be cut through the activation of the blade trigger <NUM>. Movement to the third state, in which the movable handle <NUM> is latched to the stationary housing <NUM>, reduces the potential situations whereby the tissue is unintentionally released. Also, inadvertent cutting of tissue or cutting of tissue along the wrong tissue lines can be better avoided. Additionally, the third (closed) state allows the application of constant and continuous predefined compression or range of compression on the tissue between the jaws <NUM> before, during, and after the activation of the RF energy, thereby enhancing the sealing or fusion of the tissue between the jaws <NUM>. In accordance with various embodiments, application of the RF energy can occur once the mobile handle <NUM> and jaws <NUM> are in at least the second state and once the activation button <NUM> is activated by the surgeon. In some embodiments, the application of the RF energy can occur when the mobile handle <NUM> and jaws <NUM> are in the third state and once the activation button <NUM> is activated by the surgeon.

It is noted that in various embodiments to avoid false readings, the electrosurgical generator does not measure resistance or impedance of the tissue during the supply of the RF energy to the tissue. In accordance with various embodiments, an electrosurgical system is provided that decreases thermal spread and provides efficient power delivery for sealing vessels or tissue in contact with a bipolar electrosurgical instrument through the controlled and efficient supply of RF energy.

As described throughout the application, the electrosurgical generator supplies RF energy to a connected electrosurgical instrument. The electrosurgical generator ensures that the supplied RF energy does not exceed specified parameters and detects faults or error conditions. In various embodiments, an electrosurgical instrument provides the commands or logic used to appropriately apply RF energy for a surgical procedure. An electrosurgical instrument for example includes memory having commands and parameters that dictate the operation of the instrument in conjunction with the electrosurgical generator. For example, the electrosurgical generator can supply the RF energy but the connected electrosurgical instrument decides how much or how long the RF energy is applied. The electrosurgical generator, however, does not allow the supply of RF energy to exceed a set threshold even if directed to by the connected electrosurgical instrument thereby providing a check or assurance against a faulty instrument command.

As described generally above and described in further detail below, various electrosurgical instruments, tools, or devices can be used in the electrosurgical systems described herein. For example, electrosurgical graspers, scissors, tweezers, probes, needles, and other instruments incorporating one, some, or all of the aspects discussed herein can provide various advantages in an electrosurgical system. Various electrosurgical instruments and generator embodiments and combinations thereof are discussed throughout the application. It is contemplated that one, some, or all of the features discussed generally throughout the application can be included in any of the embodiments of the instruments, generators and combinations thereof discussed herein. For example, it can be desirable that each of the instruments described include a memory for interaction with the generator as previously described and vice versa. However, in other embodiments, the instruments and/or generators described can be configured to interact with a standard bipolar radio frequency power source without interaction of an instrument memory. Further, although various embodiments may be described in terms of modules and/or blocks to facilitate description, such modules and/or blocks may be implemented by one or more hardware components, e.g., processors, Digital Signal Processors (DSPs), Programmable Logic Devices (PLDs), Application Specific Integrated Circuits (ASICs), circuits, registers and/or software components, e.g., programs, subroutines, logic and/or combinations of hardware and software components. Likewise, such software components may be interchanged with hardware components or a combination thereof and vice versa.

Further examples of the electrosurgical unit, instruments and connections there between and operations and/or functionalities thereof are described in <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT> Certain aspects of these electrosurgical generators, tools and systems are discussed herein, and additional details and examples with respect to various embodiments are described in <CIT>; <CIT>; <CIT> and<CIT>.

Claim 1:
An electrosurgical generator (<NUM>) for use in fusing or sealing tissue comprising:
a controller (<NUM>) and an RF amplifier (<NUM>) that is arranged to be connected to and to generate an electrical output for an electrosurgical instrument in accordance with signals received from the controller (<NUM>), wherein the controller (<NUM>) is arranged to:
signal the RF amplifier (<NUM>) to, in a first stage, apply RF energy to an area of tissue and to increase the applied voltage in accordance with a dynamic first voltage ramp,
determine a peak condition of the area of tissue affected by the applying of the first stage RF energy, wherein the determined peak condition corresponds to a boiling point of fluid in the area of tissue,
once the peak condition is determined,
signal the RF amplifier (<NUM>) to, in a second stage, reduce the voltage of the RF energy being applied to the area of tissue from a first to a second voltage,
signal the RF amplifier (<NUM>) to, in a third stage, increase the applied voltage in accordance with a second voltage ramp to a third voltage, and wherein the third voltage is between the first voltage and the second voltage,
signal the RF amplifier (<NUM>) to, in a fourth stage, maintain the applied voltage constant at the third voltage for a predetermined period of time, and
signal the RF amplifier (<NUM>) to terminate the application of the RF energy to the area of the tissue after the pre-determined period of time has elapsed.