Patent Description:
Surgical procedures often involve cutting and connecting bodily tissue including organic materials, musculature, connective tissue and vascular conduits. For centuries, sharpened blades and sutures have been mainstays of cutting and reconnecting procedures. As bodily tissue, especially relatively highly vascularized tissue is cut during a surgical procedure, it tends to bleed. Thus, medical practitioners such as surgeons have long sought surgical instruments and methods that slow or reduce bleeding during surgical procedures.

More recently, electrosurgical instruments have become available that use electrical energy to perform certain surgical tasks. Typically, electrosurgical instruments are hand instruments such as graspers, scissors, tweezers, blades, needles, and other hand instruments that include one or more electrodes that are configured to be supplied with electrical energy from an electrosurgical unit including a power supply. The electrical energy can be used to coagulate, fuse, or cut tissue to which it is applied. Advantageously, unlike typical mechanical blade procedures, application of electrical energy to tissue tends to stop bleeding of the tissue.

Electrosurgical instruments typically fall within two classifications: monopolar and bipolar. In monopolar instruments, electrical energy of a certain polarity is supplied to one or more electrodes on the instrument. A separate return electrode is electrically coupled to a patient. Monopolar electrosurgical instruments can be useful in certain procedures, but can include a risk of certain types of patient injuries such as electrical burns often at least partially attributable to functioning of the return electrode. In bipolar electrosurgical instruments, one or more electrodes is electrically coupled to a source of electrical energy of a first polarity and one or more other electrodes is electrically coupled to a source of electrical energy of a second polarity opposite the first polarity. Thus, bipolar electrosurgical instruments, which operate without separate return electrodes, can deliver electrical signals to a focused tissue area with a reduced risk of patient injuries.

Even with the relatively focused surgical effects of bipolar electrosurgical instruments, however, surgical 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 coagulation 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 instrument. However, even for a highly experienced surgeon, it can be difficult for a surgeon to assess how quickly a mass of combined tissue types grasped in an electrosurgical instrument will be fused a desirable amount.

Attempts have been made to reduce the risk of tissue damage during electrosurgical procedures. For example, previous electrosurgical systems have included generators that monitor an ohmic resistance or tissue temperature during the electrosurgical procedure, and terminated electrical energy once a predetermined point was reached. However, these systems have had shortcomings in that they have not provided consistent results at determining tissue coagulation, fusion, or cutting endpoints for varied tissue types or combined tissue masses. These systems can also fail to provide consistent electrosurgical results among use of different instruments having different instrument and electrode geometries. Typically, even where the change is a relatively minor upgrade to instrument geometry during a product's lifespan, the electrosurgical unit must be recalibrated for each instrument type to be used, a costly, time consuming procedure which can undesirably remove an electrosurgical unit from service. <CIT> discloses an example of a bipolar electrosurgical element having three electrodes for both cutting and sealing tissue.

The present invention provides an electrosurgical system as recited in Claim <NUM>.

The present inventions may be understood by reference to the following description, taken in connection with the accompanying drawings in which the reference numerals designate like parts throughout the figures thereof.

An electrosurgical system includes an electrosurgical unit or generator capable of supplying radio frequency energy to one or more removably coupled electrosurgical instruments or tools. Examples of such instruments and connectors between the instrument and the electrosurgical unit are provided in the drawings. Each instrument is particularly designed to accomplish particular clinical and/or technical operations or procedures. Additionally, the coupling or partnership between the electrosurgical unit and instruments are specifically provided to further enhance the operational capabilities of both the electrosurgical unit and instruments such that clinical and/or technical operations are achieved.

One such electrosurgical instrument of a system in accordance with the invention is shown in <FIG>, which illustrate a fusion and cutting electrosurgical instrument <NUM> connectable to an electrosurgical unit. As illustrated, the instrument includes jaws <NUM> for manipulating tissue and the actuator <NUM> for manipulating the jaws. A shaft <NUM> connects the jaws to the actuator. In one embodiment, the shaft and jaws are sized and arranged to fit through a cannula to perform a laparoscopic procedure. In one embodiment, the actuator includes a barrel connected to a pivotable trigger <NUM> for opening and closing of the jaws and to capture and/or compress tissue between the jaws and a rotatable knob <NUM> and connector providing rotational movement of the jaws. The actuator may also include switches <NUM>, <NUM> to activate cut, coagulate, seal, fuse or other electrosurgical activities and indicators to identify or highlight the activated or deactivated activity.

The jaws <NUM> include a first jaw <NUM> and a second jaw <NUM>. The first jaw is stationary and the second jaw is movable through actuation by the actuator coupled to the second jaw via the shaft and/or components therein. In one embodiment, both jaws may be movable or mobility of the jaws reversed, e.g., the movable jaw is stationary and the stationary jaw is movable. It should also be noted that the first or second jaw being upper or lower jaws is relative as the shaft and the jaws are rotatable and thereby can assume either position. The first jaw includes four electrodes. The first and second electrodes 103a, 103b are substantially hemispherical in shape and cover or occupy a majority of the total surface area of the first jaw. In one embodiment, the hemispherical shape of the electrodes and/or a corresponding mating shape of the second jaw promote tissue after being cut to slide away or otherwise disengage from the jaw. The first and second electrodes are also mirror image of each other and thereby occupy equal halves or side portions along the first jaw <NUM> as the electrodes extend substantially along the length of the second jaw <NUM>. Disposed between the first and second electrodes are third and fourth electrodes 105a, 105b generally rectangular in shape extending substantially perpendicular relative to the first and second electrodes 103a, 103b and also extending along the length of the first jaw. The edges or the upper portions of the third and fourth electrodes can be beveled or otherwise tapered, slanted, rounded or curved to provide an atraumatic edge to assist in a surgical procedure, e.g., grasping tissue, or alternatively a defined edge to assist for example in cutting tissue.

The third electrode 105a extends towards the second jaw and the fourth electrode 105b extends away from the second jaw. The third electrode 105a extends or has a height somewhat greater than the height or extension of the fourth electrode 105b extending out of the first jaw. The fourth electrode also includes a distal portion 105b' that extends along the tip of the first jaw <NUM> curving up along the tip. The lengthwise path of the third and fourth electrodes substantially follows the lengthwise shape of the first jaw. Thus, in the illustrated embodiment, the third and fourth electrodes are somewhat curvilinear.

When the first and second jaws <NUM>, <NUM> are closed, e.g., in a proximate relationship with each other, the third electrode 105a is substantially covered by the second jaw <NUM> and thereby leaving the third electrode unexposed. The fourth electrode 105b however remains uncovered regardless of the position of the second jaw. Each of the electrodes on the first jaw are electrically insulated or isolated from each other. Additionally, operationally, each electrode can assume a particular electrical polarity. As such, each electrode can assist in accomplishing a particular surgical functionality, e.g., cut, coagulation, fuse, seal, weld, etc. In one embodiment, the second jaw can also include one or more electrodes, e.g., a fifth or sixth electrode, which in conjunction with the electrodes on the first jaw can also assist in accomplishing the desired surgical functionality.

In one embodiment, when the first and second jaws <NUM>, <NUM> are closed (or not fully opened or partially closed) and a user activates a coagulation operation or condition, the first and second electrodes 103a, 103b assume a particular polarity and a fifth electrode <NUM> assumes an opposite polarity, through which RF energy is transmitted through clamped tissue between the first and second jaws to coagulate the tissue. Likewise, when the user activates a cut operation and the first and second jaws are closed, the first and second electrodes 103a, 103b assume a particular polarity and the third electrode 105a on the first jaw assumes an opposite polarity to first coagulate the tissue and then to cut tissue between the first and second jaws <NUM>, <NUM> and in particular at a point or section where the third electrode 105a contacts the tissue between the jaws. In one particular embodiment, in a cut operation with the first and second jaws are closed, the first and second electrodes 103a, 103b assume opposite polarity to coagulate the tissue up to and/or prior to complete coagulation or a predetermined pre-cut condition. After reaching the pre-cut condition based on a predetermined phase value, in one embodiment, the first and second electrodes 103a, 103b assume a polarity opposite to the polarity of the third electrode 105a. In one embodiment, the actuator <NUM> includes a trigger switch that is inactive or not activated by the position of the trigger positioned away from the switch.

Additionally, when the first and second jaws are not closed (fully opened or partially opened) and a user activates a coagulation operation or condition, the first electrode 103a assumes a particular polarity and the second electrode 103b assumes an opposite polarity, through which RF energy is transmitted through tissue between the first and second electrodes 103a, 103b to coagulate the tissue. Likewise, when the user activates a cut operation and the first and second jaws are not closed, the first and second electrodes assume a particular polarity and the third and fourth electrode 105a, 105b on the first jaw <NUM> assumes an opposite polarity to first coagulate the tissue and then to cut tissue between the electrodes and in particular at a point or section where the third electrode contacts the tissue between the jaws. It should be appreciated that over or completely coagulating tissue increases the difficulty in cutting the tissue as the tissue's conductivity is substantially reduced. This is contrary to the tendency to "over coagulate" tissue to ensure that blood loss is avoided (i.e., the tissue is sealed).

In one embodiment, a trigger switch <NUM> of the actuator <NUM> is activated by the position of the trigger <NUM> causing contact with the switch. The trigger in the illustrated embodiment includes a flexible arm <NUM> connected to or incorporated with the trigger utilized to activate or deactivate a trigger switch in the actuator <NUM>. The trigger switch <NUM> is internal or housed within the actuator and not accessible by a surgeon. The trigger switch however activates or permits the activation or effect of one or more external switches that is accessible by the surgeon. For example, a "cut" button or switch accessible by a surgeon will not operate or cause the application of RF energy to cut tissue even if the button is depressed by the surgeon unless the internal trigger switch is also activated. In one embodiment, the internal trigger switch is only activated depending on the position of the trigger and/or the jaws. The internal trigger switch can also be activated via relays based on commands or programming provided by the electrosurgical unit, the instrument and/or the connector. It should be appreciated that in various embodiments the internal trigger switch does not activate or permit by itself the activation of RF energy and thereby avoids unintended operation of the instrument without active and deliberate participation by the surgeon. Additionally, it should be appreciated that in various embodiments the switches accessible by the surgeon can only activate while the internal trigger switch is also simultaneously active or activated and thereby avoids unintended operation of the instrument without active and deliberate participation by the surgeon and active communication or deliberate programming or commands embedded or provided for the electrosurgical unit, the instrument and/or the connector.

It should thus be appreciated that tissue between the first and second jaws can be cut with the jaws closed or not closed. Additionally, tissue can be cut beneath and/or in front of the first jaw, i.e., tissue not between the first and second jaws, when the first and second jaws are not closed (the cutting occurring to the tissue between the fourth and first electrodes; the fourth and second electrodes; and/or the fourth and first and second electrodes). It should also be appreciated that the electrodes to assume the appropriate polarity or connection for a particular operation, e.g., cut or coagulation, are switched in or connected to the energizing circuitry of the electrosurgical unit to apply the specific RF energy to cut or coagulate tissue. Such switching or control information in one embodiment is provided via script data stored on a memory chip of a plug adapter or coupler connectable to the electrosurgical instrument.

As previously described, in one embodiment, the first jaw <NUM> is stationary or not movable and includes inner and outer vertical electrodes. Such an electrode configuration provides directed energy delivery based on the position of one jaw relative to the other jaw. For example, the electrode configuration provides cutting at the tip of a jaw and/or along the length of both the outer and inner surfaces of the jaw. Also, with the electrode configuration being located on a jaw that is stationary relative to the other jaw operation when the jaws are open can be performed such that a surgeon can manipulate the direction or path of the cut directly through manipulation of the actuator as the jaw is stationary in relation to the shaft and the actuator. In one embodiment, tissue captured between the jaws can also be cut by the electrodes on both jaws operating together.

It should be appreciated that the addition of multiple electrodes on one or more jaws is not a trivial design choice. Reducing the number electrodes is often desired, especially in the limited confines of laparoscopic procedures, to avoid shorting or undesired thermal spread or modification of tissue, e.g., charring or cutting of tissue, introduced at least by the additional conductive material proximate the active or energized electrodes. Accordingly, the electrodes as provided in various embodiments are specifically arranged, structured and utilized to overcome such challenges.

Wires may be welded onto the electrodes in the first jaw <NUM>. The wires are routed around a rotary connector <NUM> and conductive rings 24a-24d are attached to the rotary connector within the actuator <NUM>. A rotary lock is installed and holds the conductive rings in place. Conductive ring 24a is coupled to the electrode 103a and conductive ring 24d is coupled to the electrode 103b. The conductive ring 24b is coupled to the electrode 105a and conductive ring 24c is coupled to the electrode 105b. The rotary connector <NUM> includes one or more slots through which wires from electrodes are threaded or managed through slots. Conductive rings are secured to the rotary connector such that individual corresponding wires for associated electrodes are electrically connected to associated conductive rings. As such, the conductive rings rotate as the rotary connector rotates along with the associated wires extending from the electrodes of the jaws through the shaft and to the rotary connector and thus the wires do not wind around the shaft as the jaws are rotated.

The actuator <NUM> also includes contact brushes 26a-d are disposed in contact with an associated conductive ring 24a-d. For example, in the illustrated embodiment, contact brush 26a is positioned next conductive ring 24a. Each contact brush is also connected to a wire or similar connections to the connector and ultimately to an electrosurgical unit to provide or communicate RF energy, measurement, diagnostic or similar signals through an associated electrode at the jaws of the electrosurgical instrument. Slots within the handle of the actuator facilitate the wire placement and connection with a contact brush and the electrosurgical unit. As such, the conductive rings provide a conduction or communication surface that is continually in contact with the contact brushes and vice versa regardless of the rotation of the shaft. The contact brushes are slanted or biased to maintain contact with the conductive rings.

A "U" shaped tube clip <NUM> within the actuator <NUM> is welded onto a wire in which the other end of the wire is welded to the second jaw <NUM>. The second jaw <NUM> is held in place by a pull tube. The pull tube serves as an electrical connection for the second jaw <NUM>. The conductive rings and clip provides constant electrical conductivity between the electrodes and the electrosurgical unit while simultaneously allowing or not hindering complete <NUM> degrees of rotation in any direction of the jaws <NUM>, <NUM>. For example, wires coupled to the electrodes to the rings or clip follow the rotational movement of the jaws and the shaft attached thereto and as a result do not get intertwined or tangled within or along the shaft or the actuator thereby limiting rotational movement, disconnecting or dislodging the connections and/or interfering with operation of the actuator.

Individual wires may be welded to individual electrodes of the jaws of the electrosurgical instrument. The wires, e.g., wire <NUM>, are threaded along the shaft connected to the jaws through a rotary knob and into slots in a rotary connector <NUM>. Some of the wires are placed on one side of the connector and other wires on an opposing side of the connector. The wires are staggered along the length of the connector to match the staggered placement of the conductive rings. The staggered placement prevents inadvertent shorting or conduction between rings. Conductive rings are thus slide over the connector and are placed in spaced slots along the connector to mate each conductive ring to an associated staggered wire. Individual wires are also installed into slots in the handle of the actuator and an associated contact brush is installed over the associated wire to mate each wire to an associated contact brush. The rotary connector thus installed into the handle of the actuator mates or sets up an electrical connection or conduction area for each conductive ring with a corresponding contact brush.

Electrosurgical systems and processes may apply monopolar or bipolar highfrequency electrical energy to a patient during surgery. Such systems and processes are particularly adapted for laparoscopic and endoscopic surgeries, where spatially limited access and visibility call for simple handling, and are used to fuse blood vessels and weld other biological tissue and in one aspect to cut, dissect and separate tissue/vessels. The systems and processes may include the application of RF energy to mechanically compressed tissue to thereby fuse, weld, coagulate, seal or cut the tissue. In various embodiments, the determination of the end-point of the electrosurgical process is given by monitoring or identifying the phase shift of voltage and current during the process. Unlike impedance, the phase shift changes are more pronounced at times where the tissue desiccates and the fusion process completes, and hence offers a more sensitive control value than the impedance. Accordingly, the application of RF energy via an electrosurgical unit in conjunction with the measuring or monitoring of phase shift via an electrosurgical controller are provided to fuse, weld, coagulate, seal, cut or otherwise electrically modify or affect vessels and tissue.

Measurement of the dielectric properties of the tissue and control and feedback of the phase difference allows for a precise control and feedback mechanism for various tissue types, regardless of the tissue size. For example, a controller of the electrosurgical unit is configured to determine the product of dielectric constant and conductivity, as well as the phase difference between the applied voltage and current to monitor and control the tissue electrosurgical process. In particular, control and feedback circuitry of the controller determines when the phase difference reaches a phase shift value determined by the results of dielectric and/or conductivity measurements. When such a threshold or derived threshold is reached, the electrosurgical process is terminated or another operation is commenced or condition activated. An indicator, e.g., visual or audible, is provided to signal the termination or state/operation change and in one aspect the controller restricts (completely, nearly completely or to a predetermined minimum) further delivery of electrical energy through the electrodes. In one embodiment, the electrosurgical instrument in conjunction with the controller thereby provides atraumatic contact to the connecting tissue and provides enough burst pressure, tensile strength, or breaking strength within the tissue.

In one arrangement, instead of the tissue quickly reaching a pre-determined phase (e.g., ranging from <NUM> to <NUM> degrees, depending on type of tissue), the measured phase shift approaches the cut-off threshold asymptotically. Such an asymptotic approach can require an extended amount of time to reach a final phase threshold. As such, instead of depending on the phase value to reach a definite value alone, additionally the derivate of the phase can be used to avoid asymptotic approaches to a finalized phase value. Additionally, the determined phase value can be overshot without being detected or before the processor is able to recognize that a final phase stop has been reached. As such, instead of solely relying on the phase value to reach a definite value alone, the derivate of the phase is also used.

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

In accordance with various embodiments, continuous and/or periodically monitoring the phase value of the tissue being contacted can be correlated to a transition from one tissue condition or type to the next or from one tissue condition or type to no contact.

In various embodiments, continuous and/or periodically monitoring of the phase value of the tissue being treated can be correlated to either a change in tissue type or a change in the tissue properties due to delivery of energy. In one embodiment, based on the monitoring of the phase value of tissue, the output current and voltage to the instrument can be modified (e.g., increased or decreased based on the desired tissue effect (Cut, Coag, or Fuse)), electrodes can be activated or deactivated, and delivery of energy to the active accessory can begin or end.

Electrosurgical modality transitions based on the phase value of the tissue for electrosurgical instruments in accordance with various embodiments of the invention can be characterized as:.

In one embodiment, when coming into contact with tissue of specific phase values, the modalities (Cut, Coag, and Fuse) of the active instrument could be rendered active or inactive. In another embodiment, when coming into contact with tissue of specific phase values, an instrument can automatically provide energy to the tissue (cut, coagulate, fuse, weld or any combination thereof and/or the above noted modalities) until a predetermined phase value is reached.

In one embodiment, a visual, audible, and/or tactile indication can be used to indicate a tissue type that the active instrument is in contact with and thereby the electrosurgical instrument can probe for a specific tissue type. When used in combination with multiple electrodes of the active electrosurgical instrument, combinations of tissue type could be indicated visually, audibly, and/or tactilely and specific electrodes can be activated to provide energy to a portion of the device as desired to perform a specific surgical operation and based on the specific tissue.

In one embodiment, in order to cut tissue using bipolar RF energy, the tissue being treated cannot be desiccated or dehydrated to a point in which the collagen seal is all that remains. At this point the "seal" is unable to conduct electricity in the manner necessary or safely cut the tissue utilizing bipolar energy delivery (e.g., tissue resistance is too high). Likewise, at this point, cutting the seal or the tissue around the seal utilizing a mechanical (nonenergized) blade or cutting instrument can also be difficult due to for example the tissue calcifying. Therefore, when utilizing phase values to identify the transitions of "pre-cut" or "partial seal", the tissue can be coagulated to known phase value less than the predetermined phase value indicated for complete tissue coagulation. Subsequently, cutting is performed (either mechanically or electrically). After cutting, energy delivery can be continued until a predetermined phase values indicated for complete tissue sealing is reached.

It should be appreciated that the tissue to be cut should have minimal thermal damage or desiccation to ensure that the tissue is still conductive to be electrically cut. In one embodiment, the electrosurgical instrument provides that about <NUM>-<NUM> of lateral thermal damage outside of the jaws of the device at a phase shift of <NUM>°. The spacing between the coagulating electrodes electrosurgical instrument is about <NUM>" or <NUM> such that at a phase shift beyond <NUM>° the tissue is desiccated too much to be cut effectively. As such, in one embodiment, the larger the spacing between electrodes, the higher a pre-cut transition point or condition can be set and a lower pre-cut transition supports closer electrode spacing. The lower pre-cut transition represents the phase value in which less coagulation occurs versus complete tissue coagulation. Additionally, applying RF energy, e.g., voltage faster or at a high or steep rate, is provided to support closer electrodes as the pre-cut transition is lower than a pre-cut transition with larger spacing between electrodes. Likewise, applying RF energy at a slower or less steep rate can be provided for larger spaced electrodes. Additionally, with the tissue being enclosed in between jaws, tissue within the confines of the jaw subjected to higher temperatures than on the outside edges of the jaw. As such, tissue less confined or subject to lower temperatures can have reduced thermal damage and thereby a higher pre-cut transition point can be used.

Referring to <FIG>, in one embodiment, a pre-cut process is shown which initially starts for example by the receipt of a cut command (<NUM>) from the activation of a button or switch on the actuator. The activation of the cut button is communicated or recognized by the electrosurgical unit coupled to the electrosurgical instrument. In one embodiment, a processor within the electrosurgical unit instructs or initiates the output or supply of RF energy (<NUM>) to the electrosurgical instrument. However, the RF energy supplied is not energy sufficient to cut tissue disposed at the jaws of the electrosurgical instrument. Instead the RF energy supplied is used for coagulation which is lower than the energy sufficient to cut tissue. The processor monitors the phase between the current and voltage of the RF energy being supplied to the tissue (<NUM>). In one embodiment, through current and voltage monitoring circuitry and filters, the phase between the current and voltage of the RF energy is monitored. A comparison is made to a pre-cut phase condition or switch (<NUM>). In one embodiment, the pre-cut phase condition is a predetermined value or range of values that is specific for the particular electrosurgical instrument and the type of tissue indicated to be used or specifically used or to be treated by the instrument. In other embodiments, the pre-cut phase condition is determined dynamically based or relative to initial or periodic determinations about the tissue type via for example tissue permittivity and/or conductivity measurements to identify different predetermined values or range of values for a given tissue type. For example, an initial determination of a tissue type is used to lookup or compare to a table of values, e.g., pre-cut phase values, that are experimentally or otherwise predetermined to be the optimal or specific phase value to identify a pre-cut phase condition.

As previously described, the pre-cut phase condition is identified as a point or condition in which the tissue being applied with RF energy is nearly coagulation but less than or not up to the point of complete coagulation, e.g., near complete desiccated, dehydrated and/or calcification of the tissue. If it is not determined that the pre-cut phase switch is reached or exceeded, the process continues as the RF energy continues to be supplied and the phase monitored. Once it is determined that the pre-cut phase condition has been met, cutting of the tissue then proceeds. In one embodiment, the processor commands or initiates the raising or initiation of the RF energy suitable for cutting tissue at the jaws of the electrosurgical instrument (<NUM>). In one embodiment, the application of RF energy to pre-cut and then cut tissue is quick such that the rate at which the electrosurgical unit reaches or provides the maximum output voltage is accelerated. If there is a long ramp-up cycle or step function for the voltage to follow, the tissue intended to be cut will be only coagulated. As such, by the time the electrosurgical unit reaches the cut voltage levels the tissue will be too dessicated to properly cut.

In one embodiment, the process continues as phase between applied current and voltage is measured and/or monitored to determine or ensure that the tissue is properly cut. Additionally, in one embodiment, after the tissue is cut, complete coagulation of the tissue can be performed or initiated as RF energy for coagulation is supplied again to the tissue and a determination is made that the tissue has been coagulated.

The tissue pre-cut and then cut is the same or nearly the same, but it should be noted that the tissue can refer to surrounding tissue first being coagulated to a pre-cut condition and tissue between the nearly coagulated tissue is then cut. The application of the coagulation RF energy and/or cut RF energy is also dependent on the electrodes supplying the associated RF energy. As such, the tissue affected can also be based on the location or application of the RF energy from the electrode locations to be pre-cut and then a cut using different sets of electrodes. For example, when a cut command is initiated, one or more electrodes can be energized to apply RF energy to coagulate tissue in contact with the one or more electrodes and once a pre-cut condition is reached, one or more different electrodes are energized to apply RF energy to cut tissue in contact with these different electrodes. Thus, in one embodiment, when a cut button is activated on the electrosurgical instrument, tissue in one area may be supplied RF energy for coagulation to a pre-cut condition and a different tissue in a different are may be subsequently supplied RF energy to cut the different tissue. In one embodiment, one or more electrodes are used in transmitting RF energy for coagulation and one or more electrodes different from the other electrode used for coagulation are used in transmitting RF energy for cutting. Additionally, one or more electrodes can be used as a common or shared electrode utilized to accommodate both the transmission of RF energy for coagulation and cutting.

In one embodiment, an electrosurgical unit <NUM> can comprise input/output circuitry <NUM>, RF supply circuitry <NUM>, a phase discriminator <NUM> and a processor <NUM>. One or more circuitry may be incorporated into an associated circuitry. For example, the RF supply circuitry may be included with the input/output circuitry and vice versa. The input/output circuitry receives and transmits RF energy from the RF supply circuitry and out of the electrosurgical unit and to a connected electrosurgical instrument (not shown). The input/output circuitry also receives tool data and/or tissue data from the electrosurgical instrument and/or through a connector therebetween. In one embodiment, the phase discriminator calculates a phase difference between the applied voltage and current from the RF supply circuitry. In one embodiment, the applied voltage and current are rectified and compared or combined, e.g., through an XOR logic gate, to generate a pulse width modulated signal. The duty cycle of the generated signal mirrors or represents the phase difference between the applied voltage and current. The determined phase difference is then supplied to a processor that compares to a predetermined phase threshold based on a particular tissue in contact with the electrosurgical instrument. In one embodiment, the processor provides the above described process of determining a pre-cut condition to completing a cut.

In one embodiment, an electrosurgical generator includes an RF amplifier <NUM>, RF amplifier control and monitor <NUM>, energy monitor <NUM> and relay and tissue measurement <NUM>. The electrosurgical generator is coupled to a <NUM> Voltage main input. The main input is isolated with a low leakage isolation transformer of a power supply <NUM>. The power supply provides operational voltages for the control processor <NUM> and the RF amplifier <NUM>. Additionally, the power supply includes two 50VDC output modules connected in series to provide a total output of 100VDC and <NUM> Amps. RF power is generated by the RF amplifier, e.g., a switched mode low impedance RF generator that produces the RF output voltage. In one embodiment, a <NUM> peak cut voltage for cutting and <NUM> Amp current for coagulation/fusing is generated.

Fusing tissue in one embodiment involves applying RF current to a relatively large piece of tissue. Because of the potentially large tool contact area tissue impedance is very low. Accordingly, to deliver an effective amount of RF power, the current capability of the RF amplifier is large. As such, where a typical generator might be capable of <NUM> to <NUM> amps of current, the RF amplifier of the generator can supply more than <NUM> Amps RMS into low impedance loads. This results in rapid tissue fusion with minimal damage to adjacent tissue.

The RF amplifier circuitry has redundant voltage and current monitoring. One set of voltage and current sensors are connected to the RF amplifier control and monitor and are used for servo control. The voltage and current can also be read by the processor <NUM> using an analog to digital converter (ADC) located on the RF amplifier control and monitor. The RF amplifier control and monitor also has an analog multiplier, which calculates power by computing the product of the voltage and current. The RF amplifier control and monitor uses the average value of voltage and current and does not include a phase angle and thus is actually calculating Volt Amps Reactive (VAR) rather than actual power. A second set of voltage and current sensors are also connected to the energy monitor <NUM>. The signals are connected to an ADC for redundant monitoring of the voltage and current. The processor multiplies the voltage and current readings to verity that power output does not exceed <NUM> Watts. The energy monitor has monitoring circuits that are completely independent of the RF amplifier control and monitor. This includes the ADC, which has an independent voltage reference.

The RF amplifier in one embodiment is a switching class D push pull circuitry. As such, the amplifier can generate large RF voltages into a high tissue impedance, as well as large RF currents into low tissue impedance. The output level of the RF amplifier is controlled by Pulse Width Modulation (PWM). This high voltage PWM output signal is turned into a sine wave by a low pass filter on the RF amplifier. The output of the filter is the coagulation output of the RF amplifier. The output is also stepped up in voltage by an output transformer resulting in the cut output of the RF amplifier. Only one output is connected to the control servo on the RF amplifier control and monitor at a time and only one output is selected for use at a time.

Coupled to the RF amplifier is the RF amplifier control and monitor <NUM>. The RF amplifier control and monitor <NUM> in one embodiment receives voltage and current set points, which are input by the user through a user interface, to set the output level of the RF amplifier. The user sets points are translated into the operating levels by digital to analog converters of the RF amplifier control and monitor. The user sets points are translated into the operating levels by digital to analog converters of the RF amplifier control and monitor. The set points in one embodiment include a maximum voltage output, maximum current output, maximum power output, and a phase stop. The servo circuit of the RF amplifier control and monitor controls the RF output based on the three set points. The servo circuit as such controls the output voltage of the RF amplifier so that the voltage, current, and power set points are not exceeded. For example, the output of the ESG is restricted to be less than <NUM> watts. The individual voltage and current set point can be set to exceed <NUM> watts depending on the tissue impedance. The power servo however limits the power output to less than <NUM> watts.

The RF output voltage and current are regulated by a feedback control system. The output voltage and current are compared to set point values and the output voltage is adjusted to maintain the commanded output. The RF output is limited to <NUM> Watts. Two tool connections are supported by using relays <NUM> to multiplex the RF output and control signals. The EMI line filter <NUM> limits the RF leakage current by the use of an RF isolation transformer and coupling capacitors.

The cut and coagulation output voltages of the RF amplifier are connected to the relay and tissue measurement circuitry <NUM>. The relay and tissue measurement circuitry in one embodiment contains a relay matrix, which steers the RF amplifiers output to one of the three output ports of the electrosurgical unit. The relay matrix also selects the configuration of the tool electrodes. The RF output is always switched off before relays are switched to prevent damage to the relay contacts. To mitigate against stuck relays steering RF to an idle output port each output port has a leakage current sensor. The sensor looks for unbalanced RF currents, such as a current leaving one tool port and returning through another tool port. The current sensors on are located on the Relay PCB, and the detectors and ADC are on the energy monitor PCB. The CPU monitors the ADC for leakage currents. Any fault detected results in an alarm condition that turns off RF power.

The relay and tissue measurement circuitry also contains a low voltage network analyzer circuit used to measure tool impedance before RF power is turned on. The circuit measures impedance and tissue phase angle and in one embodiment using a 10V signal operating at <NUM>. The processor <NUM> uses the impedance measurement to see if the tool is shortcircuited. If a Tool A or B output is shorted the system warns the user and will not turn on RF power. The RF amplifier is fully protected against short circuits. Depending on the servo settings the system can operate normally into a short circuit, and not cause a fault condition. In one embodiment, initial impedance and/or phase measurements can determine if the jaws are open and/or having no tissue in contact with the jaws and/or the jaws are dirty, e.g., excessive or interfering eschar build-up.

Voltage and current feedback is provided using isolation transformers to insure low leakage current. The processor <NUM> computes the power output of the RF amplifier and compares it to the power set point, which in one embodiment is input by the user. The processor also monitors the phase lag or difference between current and voltage. Additionally, in one embodiment, the processor matches the different phase settings, which depend on tissue types to the monitored phase difference. The processor as such measures a phase shift of tissue prior to any application of RF energy. As will be described in greater detail below, the phase measurement is proportional to tissue permeability and conductivity that uniquely identifies the tissue type. Once the tissue type is identified, the phase angle associated with an end point determination of that tissue type can be determined. The generator in one embodiment has three RF output ports (Tool A, Tool B and generic bipolar). The tool A and B ports <NUM> are used to connect smart tools, while the generic bipolar port <NUM> supports standard electro surgical tools. Audible tones are produced when the RF output is active or an alarm condition exists.

The hand and foot controls are also isolated to limit leakage current. The control processor checks the inputs for valid selections before enabling the RF output. When two control inputs from the switches are simultaneously activated the RF output is turned off and an alarm is generated. Digital to analog converters are used to translate control outputs into signals useable by the Analog Servo Control. The control set points are output voltage and current. The analog to digital converter is used to process the analog phase angle measurement. Voltage RMS, current RMS, and power RMS information from the controller is also converted into a form usable for presentation to the user. The digital I/O bus interface <NUM> provides digital communication between the user, controller and hand/foot switches. Isolation circuitry is used to eliminate a possible leakage path from the electrosurgical generator. It also provides communication between the user and the generator though a data channel protocol.

In one embodiment, there are four tool Interface circuits in the unit. These circuits are used to electrically isolate the user input switches from mains power inside the system. The four tool interface circuits are identical and have an on board microprocessor to read the user switch inputs as well as the tool crypto memory and script memories. The switch closure resistance is measured with an ADC to eliminate a contaminated switch contact being read as a closure. Switch closures below <NUM> Ohms are valid, while any reading above <NUM> Ohms is open. Readings between <NUM> and <NUM> Ohms are considered to be faulty inputs.

The four tool interface circuits communicate with the processor using an RS485 network. Each tool interface circuit has jumpers to select its address and location in the unit. The RS485 interface is isolated to eliminate any potential leakage current paths. One tool interface circuit is connected to each of the Tool A and B ports. A third tool interface circuit is connected to the DC output port, and the fourth circuit is connected to the rear panel foot switch inputs. The processor is the network master and each of the four circuits is a network slave. The processor polls each circuit for input. The tool interface circuitry can only reply to commands. This makes the network deterministic and prevents any kind of dead lock. Each Tool Interface circuit is connected to a System OK logic signal. If a system error is detected by a Tool Interface circuit, this signal is asserted. The processor monitors this signal and indicates a fault. This signal also has a hardware connection to the RF amplifier control and monitor and will disable the RF amplifier when asserted. A system error could be two input switches activated at the same time, or a loss of communication with the processor. The Tool A & B ports as well as the DC port have a micro switch that detects when a tool is plugged into the receptacle. Until this switch is depressed the Tool Interface circuit front panel connections are configured off to prevent any leakage current flowing from front panel connections. Once the switch is depressed the Tool Interface allows the processor to initiate reads and writes to the tool crypto memory and script memory. Once a tool is detected a window opens in the user interface display showing the type of tool connected and status. The generic bipolar port supports legacy tools, which do not have any configuration memory. The tissue measurement circuitry is used to monitor the bipolar connection contacts. When a bipolar tool is connected the tool capacitance is detected and the processor opens the bipolar tool window on the user interface display and shows status for the bipolar tool. The DC port is used to interface with <NUM> Volt DC powered custom surgical tools. When a tool is plugged into this port a window opens in the user interface display showing the type of tool connected and status. When the DC tool script commands power on, the processor closes a relay on the Power Control and Isolation circuitry <NUM> turning on the isolated <NUM> Volt tool power.

The power control and isolation circuitry <NUM> has two other features. It controls the <NUM> Volt power supply that drives the RF amplifier. This power supply is turned on by a relay controlled from the RF amplifier control and monitor. The processor commands this power supply on via the RF amplifier control and monitor. If the RF amplifier control and monitor is reset or detects a fault condition, the relay will not operate leaving the <NUM> Volt power supply off. Also located on the power control and isolation circuitry is a RS485 isolation circuit that adds an extra layer of isolation.

The front panel interface circuitry <NUM> is used to connect the front panel control switches and LCD display to the processor. The front panel interface circuitry also contains a microprocessor, which is powered by an isolated standby power supply, which is on whenever the main power switch is on. When the front panel power switch is pressed, the microprocessor uses a relay on the Power Control and Isolation circuitry to turn on the main logic power supply. When the button is pressed to turn power off, the microprocessor signals a power off request to the processor. When the processor is ready for power to be turned off it signals the microprocessor to turn off power. The power control relay is then opened, turning off the main power supply.

In one embodiment, the generator accepts only single switch input commands. With no RF active, e.g., RF energy applied, multiple switch closures, either from a footswitch, tool, or a combination of footswitch and tool are ignored. With RF active, dual closures shall cause an alarm and RF shall be terminated. The footswitch in one embodiment includes momentary switches providing activation of the application of RF energy. The switches for example when manipulated initiates activation of the RF energy for coagulation, for cutting and/or sequenced coagulation or cutting. A two-position pushbutton on the foot pedal switch allows toggling between different tools. The active port is indicated on the display of the generator and an LED on the hand tool.

In one embodiment, all RF activation results in a RF ON Tone. Activation tone volume is adjustable, between 40dBA (minimum) and 65dB (maximum) with a rear panel mounted control knob. The volume control however does not affect audio volume for alarms. Also, in one embodiment, a universal input power supply is coupled to the generator and operates over the input voltage and frequency range without the use of switches or settings. A programming port in one embodiment is used to download code to the generator and is used to upload operational data.

The generator in one embodiment provides output power has a 12V DC at <NUM> Amps. Examples of such tools that use DC power are, but are not limited to, a suction/irrigation pump, stapler, and a morcellator (tool for dividing into small pieces and removing, such as a tumor, etc.). The DC connector has intuitive one-way connection. Similar to the other tool receptacles, a non-sterile electronic chip module is imparted into the connector of the appropriate DC-powered hand tool by a one-time, one-way locking mechanism. Tool-specific engravings on both the connector and chip module ensure that the chip module fits only to the type of tool for which it has been programmed. The chip connector allows tool recognition and the storage of data on tool utilization. The DC connector is also configured to prevent improper insertion. The generator is also configured to recognize the attached DC-powered tool. The generator reads configuration data from the tool connector, allowing tool recognition and the storage of tool utilization data.

In one embodiment, phase measurement is a relative measurement between two sinusoidal signals. One signal is used as a reference, and the phase shift is measured relative to that reference. Since the signals are time varying, the measurement cannot be done instantaneously. The signals must be monitored long enough so that difference between them can be determined. Typically the time difference between two know points (sine wave cross through zero) are measured to determine the phase angle. In the case of the phase controller, the device makes the output sine wave with a precise crystal controlled clock. That exact same clock is use to read the input samples with the analog to digital converter. In this way the output of the phased controller is exactly in phase with the input of the phase controller. The phase controller in one embodiment compares the input sine wave signal to a reference sine wave to determine the amount of phase shift.

The phase controller does this comparison using a mathematical process known as a Discreet Fourier Transform (DFT). In this particular case <NUM> samples of the input signal are correlated point by point with both a sine function, and a cosine function. By convention the cosine part is called real, and the sine part is called imaginary. If the input signal has no phase shift the result of the DFT is <NUM>% real. If the input signal has a <NUM>-degree phase shift the result of the DFT is <NUM>% imaginary. If the result of the DFT has both a real and imaginary component, the phase angle can be calculated as the arctangent of ratio of the imaginary and real values.

It should be appreciated that the phase angle calculation is independent of units of the real and imaginary numbers. Only the ratio matters. The phase results of the phase controller are also independent of gain and no calculation of impedance is made in the process of calculating the phase angle. By performing a DFT, the phase controller encodes the phase measurement as a pair of numbers.

Precise knowledge of the phase endpoint prior to energy delivery allows for tighter control, and for delivery of more current than other electrosurgical units (7A, 400W). In accordance with various embodiments, the memory capability of the instrument key portion of each instrument connector allows the reading and writing of information between the electrosurgical unit and the instrument key or connector. The information can include recording treatment data (energy profile, tissue types, etc.) or data to prevent device reuse. In one embodiment, the use-before-date (UBD), number of uses, device serial number and expiration after first use values are encrypted to prevent reprocessing and reuse of the instrument key. In one example, to assist in managing inventory, the information may include the serial number of the electrosurgical unit that can be retrieved and stored into the memory upon connection of the instrument to the unit. The serial number or similar information is then used in parallel with lot and sales data to locate the electrosurgical unit and/or track electrosurgical unit's movements. Likewise, locators or trackers using GPS, RFID, IP addresses, Cellular Triangulation can be incorporated in the instruments and/or electrosurgical unit to locate and track electrosurgical units or instruments.

In one embodiment, the information may include metrics such as recording tissue types encountered during a procedure and/or tracking performance of an instrument or electrosurgical unit (how often used, number of procedures, and so on). Pre-customized surgeon settings can also be included in which the device output parameters (e.g., voltage, current, and power) stored in the connector or instrument key and read into the electrosurgical unit when connected. The specific settings can be programmed or stored prior to shipment of the instrument/connector. Diagnostic information on instrument/electrosurgical unit can also be included. For example, calibration and output verification information can be stored on the electrosurgical unit and then downloaded to the instrument key when connected. In one embodiment, software upgrades can also be delivered via the memory and the instrument ports on the electrosurgical unit.

In one embodiment, the electrosurgical generator or unit can automatically sense or identify a standard bipolar instrument insertion/connection. In one embodiment, the electrosurgical unit can compensate for or enhance a standard bipolar instrument to phase monitor and/or identify tissue or its condition. For example, a tissue measurement circuitry could be included in the electrosurgical unit or as an intermediate connector between the instrument and electrosurgical unit. The circuitry and/or program could include phase monitoring and/or tissue type or condition identification functionality. The tissue measurement circuitry in one embodiment can include a phase measurement adjustment circuit or program to account for impedance in the circuitry and cables that run between the tissue and the tool port. The circuitry may also include temperature correction as an actual change in phase value due to the instrument may be less than potential changes due to temperature fluctuations.

Using the phase difference between voltage and current as a control value in a fusion or welding process, instead of the impedance, can be further shown when characterizing the tissue electrically. When considering vessels and tissue to be a time-dependant ohmic resistor R and capacitor C in parallel (both of which depend on the tissue size and type) the phase difference can be obtained with.

The phase difference ϕ can then be expressed as <MAT>, where ρ is equal to (<NUM> / conductivity).

As such, the difference between monitoring the phase difference ϕ as opposed to the (ohmic) resistance R is that ϕ depends on the applied frequency ω and material properties only (namely, the dielectric constant ε and the conductivity), but not on tissue dimensions (namely the compressed tissue area A and tissue thickness d). Furthermore, the relative change in phase difference is much larger at the end of the fusion process than the change in tissue resistance, allowing for easier and more precise measurement.

In addition, with measurement of the initial dielectric properties of the tissue (dielectric constant ε and conductivity) at a certain frequency, the type of tissue can be determined. The dielectric properties for various types of biological tissue, arranged by increasing values of the product of dielectric constant ε and conductivity) are given in Figure <NUM> at a frequency of <NUM> (which is in the frequency range of a typical electrosurgical generator). By measurement of the product of dielectric constant ε and conductivity of the tissue (which are material characteristics and independent of tissue dimensions) before the actual tissue fusion or welding process, the phase shift required to adequately fuse or seal the specific biological tissue can be determined. The phase shift required to reliably fuse or seal the respective type of tissue is measured as function of the product of dielectric constant ε and conductivity of the tissue. Additionally, endpoint determination can be represented as a function of an initial phase reading of the tissue determination and likewise end point determination can be represented as a function of tissue properties (conductivity times relative permittivity).

As a result, (a) measurement of the dielectric properties of the tissue and (b) control and feedback of the phase difference allows for a precise control and feedback mechanism for various tissue types, regardless of the tissue size and allows employing standard electrosurgical power supplies (which individually run in a very close range of frequencies). It should be noted that however that specific frequency of the tissue properties measurement is performed can be the same or different from the specific frequency of the phase If the tissue measurement is based on the driving frequency of the generator, and various generators are used (all of which run in a close range of frequencies) though, the end points will be different. Hence, for such a case, it can be desirable to (<NUM>) use an external measurement signal (which is at the same frequency), or (b) utilize a stand-alone generator.

As such, the controller is configured to determine the product of dielectric constant and conductivity, as well as the phase difference between the applied voltage and current to monitor and control the tissue fusion or welding process. In particular, control and feedback circuitry of the controller determines when the phase difference reaches the phase shift value determined by the result of the dielectric and conductivity measurements. When this threshold is reached, the fusion or welding process is terminated. An indicator, e.g., visual or audible, is provided to signal the termination and in one aspect the controller restricts (completely, nearly completely or to a predetermined minimum) further delivery of electrical energy through the electrodes. As such, the tool generating the seal, weld or connection of the tissue provides atraumatic contact to the connecting tissue and provides enough burst pressure, tensile strength, or breaking strength within the tissue.

In one embodiment, a bipolar/monopolar single connector plug is provided to allow the connection of monopolar instruments to the electrosurgical unit. In one embodiment, the connector includes a grounding pad port <NUM> that acts as another electrode (e.g., a <NUM>th electrode (F)) that the electrosurgical unit <NUM> turns on and off through internal relays in the electrosurgical unit (FIGS. <NUM> - <NUM>). Based on the programming of the relay/electrode configuration or pattern on the instruments (e.g., stored in memory of the connector), an electrosurgical instrument <NUM> can cut and coagulate in either a bipolar manner, monopolar manner of both. In one embodiment, in bipolar mode, the electrosurgical unit <NUM> utilizes two or more electrodes, e.g., electrodes designated "B" and "C", to create active and return paths and in monopolar mode, the electrosurgical unit utilizes one or more of the electrodes as active, e.g., electrodes designated "A" through "E", and only an electrode where the grounding pad <NUM> would be designated or used as the return only electrode <NUM>, e.g., electrode designated "F". In one embodiment, switches internally or externally on the electrosurgical instrument, the connector and/or the port can be used to identify or notify the electrosurgical unit that a monopolar operation is being used. Additionally, in one embodiment phase measurements of applied RF energy can be used to identify if the monopolar pad is removed, not providing sufficient contact with the patient and/or electrical conductivity to the electrosurgical instrument.

Claim 1:
An electrosurgical system comprising:
an electrosurgical instrument comprising a first jaw (<NUM>) and a second jaw (<NUM>) arranged to open and close relative to each other, the first jaw (<NUM>) comprising:
a first electrode (103a) and a second electrode (103b) which curve over and extend along respective opposed sides of the first jaw (<NUM>), to cover or occupy a majority of the total surface area of the first jaw; and
a third electrode (105a) extending along the length of the first jaw (<NUM>) between and substantially perpendicular to the first and second electrodes (103a, 103b), which third electrode (105a) is generally rectangular in shape and extends out of the first jaw towards the second jaw (<NUM>); and
an electrosurgical generator arranged to supply radiofrequency (RF) energy to the electrosurgical instrument removably coupled to the electrosurgical generator, the generator being arranged to supply RF energy between the first electrode (103a) and the second electrode (103b) to coagulate tissue therebetween, to determine a pre-cut condition based on a phase difference between an applied voltage and an applied current of the supplied RF energy during the supply of RF energy to coagulate tissue; and the generator, after determining the pre-cut condition has been met, is arranged to supply RF energy between the first, second and third electrodes (103a, 103b, 105a) to cut tissue therebetween.