Electrosurgical systems and methods for time domain reflectometer-based tissue sensing

Abstract

A method of sealing tissue according to the present disclosure includes: grasping tissue between a first jaw member and a second jaw member; applying a signal to the grabbed tissue intended for tissue treatment based on a tissue sensing algorithm; receiving reflected signals from the first jaw member and the second jaw member; and determining a tissue characteristic based on the reflected signal. An electrosurgical system configured to implement the method is also provided.

Description

Technical Field

[0001] The present disclosure relates to electrosurgery and, more particularly, to electrosurgical systems and methods for treating tissue. Background Art

[0002] In bipolar electrosurgery, an electrical current is conducted through tissue between electrodes positioned at different polarities to heat and thereby treat the tissue. Bipolar electrosurgery typically involves the use of electrosurgical clamps, a forceps-like instrument that relies on mechanical action between its jaws to grasp, clamp, and constrict tissue. More specifically, electrosurgical clamps utilize mechanical clamping action and electrical energy to treat (e.g., cauterize, coagulate, and / or seal) the clamped tissue.

[0003] Cauterization involves the use of heat to destroy tissue, and coagulation is the process of drying tissue so that tissue cells rupture and dry out, while tissue sealing is the process of liquefying the collagen, elastin, and matrix in the tissue so that they reform into a fused mass with significantly reduced demarcation between opposing tissue structures. In order to produce an effective tissue seal, two main mechanical parameters must be accurately controlled: the pressure applied to the tissue and the gap distance between the electrodes. In addition, electrosurgical energy must be applied to the tissue under controlled conditions (e.g., controlling the intensity, frequency, and duration of application of electrosurgical energy to the tissue) to ensure that an effective tissue seal is produced. Summary of the invention

[0004] As used herein, the term "distal" refers to the portion of the description that is further away from the operator (whether a surgeon or a surgical robot), while the term "proximal" refers to the portion of the description that is closer to the operator. As used herein, terms including "generally," "about," "substantially," etc. are meant to cover up to and include variations of plus or minus 10% (e.g., manufacturing tolerances, material tolerances, usage tolerances, and environmental tolerances, measurement variations, design variations, and / or other variations). In addition, within the scope of consistency, any or all aspects detailed herein may be used in combination with any or all other aspects detailed herein.

[0005] According to the present disclosure, a method for treating tissue includes: grasping tissue between a first jaw member and a second jaw member; applying a signal to the grasped tissue for intended tissue treatment based on a tissue sensing algorithm; receiving reflected signals from the first jaw member and the second jaw member at multiple frequencies; and determining tissue characteristics or conditions at the first jaw member and the second jaw member based on the reflected signals.

[0006] In one aspect of the present disclosure, the method may further include adjusting a tissue sealing algorithm based on the determined tissue characteristics.

[0007] In another aspect of the present disclosure, the method may further include applying energy to the grasped tissue to seal the grasped tissue according to a tissue sealing algorithm, wherein the tissue sealing algorithm is independent of the tissue sensing algorithm.

[0008] In yet another aspect of the present disclosure, a tissue sensing algorithm may be controlled in a first manner and a tissue sealing algorithm controlled in a second, different manner.

[0009] In yet another aspect of the present disclosure, the delay times and / or voltages of the reflected signals at the multiple frequencies can be used to determine tissue characteristics.

[0010] In yet another aspect of the disclosure, the tissue property is impedance at each of the plurality of frequencies.

[0011] In one aspect of the present disclosure, at least a portion of a tissue sealing algorithm can adjust energy output to track the impedance versus time trajectory.

[0012] In another aspect of the present disclosure, the condition at the first jaw member and the second jaw member may be one of an open circuit condition or a short circuit condition.

[0013] In yet another aspect of the present disclosure, determining the tissue characteristic may include determining a frequency component of the reflected signal; and determining the tissue characteristic based on the determined frequency component of the reflected signal.

[0014] In yet another aspect of the present disclosure, the method may further include implementing a delay period in which no energy is applied after applying energy to the grasped tissue according to the tissue sensing algorithm and before applying energy to the grasped tissue according to the tissue sealing algorithm.

[0015] According to the present disclosure, an electrosurgical system for treating tissue includes: an electrosurgical clamp including a first jaw member and a second jaw member; and an electrosurgical generator. The electrosurgical generator includes a processor and a memory. The memory includes instructions stored on the memory that, when executed by the processor, cause the system to: apply a signal based on a tissue sensing algorithm to tissue grasped between the first jaw member and the second jaw member in anticipation of tissue treatment; receive reflected signals from the first jaw member and the second jaw member at multiple frequencies; and determine a tissue characteristic or condition at the first jaw member and the second jaw member based on the reflected signals.

[0016] In one aspect of the present disclosure, the instructions, when executed by the processor, may further cause the system to adjust a tissue sealing algorithm based on the determined tissue characteristics.

[0017] In another aspect of the present disclosure, the instructions, when executed by the processor, may further cause the system to apply energy to the grasped tissue to seal the grasped tissue according to a tissue sealing algorithm, wherein the tissue sealing algorithm is independent of the tissue sensing algorithm.

[0018] In yet another aspect of the present disclosure, the instructions, when executed by the processor, may further cause the system to control the pre-treatment algorithm in a first manner, and the tissue sealing algorithm is controlled in a second, different manner.

[0019] In yet another aspect of the present disclosure, the delay times and / or voltages of the reflected signals at the multiple frequencies can be used to determine tissue characteristics.

[0020] In one aspect of the disclosure, the tissue characteristic can be impedance at each of the plurality of frequencies.

[0021] In another aspect of the present disclosure, at least a portion of a tissue sealing algorithm can adjust energy output to track the impedance versus time trajectory.

[0022] In yet another aspect of the present disclosure, the condition at the first jaw member and the second jaw member may be one of an open circuit condition or a short circuit condition.

[0023] In yet another aspect of the disclosure, when determining the tissue characteristic, the instructions, when executed by the processor, may further cause the system to determine a frequency content of the reflected signal and determine the tissue characteristic based on the determined frequency content of the reflected signal.

[0024] A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform a computer-implemented method of treating tissue, the method comprising: grasping tissue between a first jaw member and a second jaw member; applying a signal to the grasped tissue in anticipation of tissue treatment based on a tissue sensing algorithm; receiving reflected signals from the first jaw member and the second jaw member at multiple frequencies; and determining tissue characteristics or conditions at the first jaw member and the second jaw member based on the reflected signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other aspects and features of the present disclosure will become more apparent when the following detailed description is considered in conjunction with the accompanying drawings, in which like reference numerals designate similar or identical elements.

[0026] Figure 1 is a perspective view of an electrosurgical system according to the present disclosure, the electrosurgical system including an electrosurgical clamp and an electrosurgical generator;

[0027] Figure 2A and Figure 2B yes Figure 1an enlarged perspective view of a distal end portion of the clamp, wherein the end effector assembly of the clamp is respectively disposed in a spaced apart position and an approximated position;

[0028] Figure 3 is a schematic diagram of a robotic surgical system configured for use in accordance with the present disclosure;

[0029] Figure 4 yes Figure 1 Block diagram of the generator;

[0030] Figure 5 It shows Figure 1 The electrosurgical generator is connected to Figure 1 Schematic diagram of a clamp wherein tissue is grasped by a jaw member of an end effector assembly of the clamp;

[0031] Figure 6 is a flow chart illustrating a method of treating tissue according to the present disclosure;

[0032] Figure 7 Shows from Figure 1 The generator transmits to Figure 1 Results of simulation of a signal of an end effector assembly of the clamp and a measured reflected signal at the generator;

[0033] Figure 8 It shows Figure 1 Graph of oscilloscope traces of transmitted and reflected signals in a system where Figure 1 The jaw member of the end effector assembly of the clamp is in an open position and not grasping tissue;

[0034] Fig. 9 It shows Figure 1 Graph of oscilloscope traces of transmitted and reflected pulses in a system of Figure 1 The impedance between the jaw members of the end effector assembly of the clamp is about 100 ohms;

[0035] Fig.10 is used Figure 1 Simulation of an ideal reflected pulse from a 100 ohm load in the system;

[0036] Fig.11 It is shown Figure 1 Graph of oscilloscope traces of transmitted and reflected signals in a system where Figure 1 The impedance between the jaw members of the end effector assembly of the clamp is about 50 ohms;

[0037] Fig.12 It shows Figure 1 A graph of a frequency spectrum of a clamp having a short circuit between jaw members;

[0038] Fig.13 It shows Figure 1 A graph of a frequency spectrum with an open circuit between the jaw members of a clamp in FIG.

[0039] Fig.14 is shown with Figure 1 a graph of a frequency spectrum of jaw members of a clamp of , wherein the impedance between the jaw members is approximately 50 ohms; and

[0040] Fig.15 It shows the Figure 12 to Figure 14 Table showing the amplitude of the load at different frequencies of the returned signal. DETAILED DESCRIPTION

[0041] The present disclosure enables the use of pulse time domain reflectometry to sense properties of tissue (and / or other material) grasped between the jaw members of an electrosurgical clamp. Determining the properties of tissue (and / or other material) in this manner provides the benefit of being fast and not requiring additional sensing electrodes. A single short pulse contains a wide band (many) frequencies in a single pulse. By looking at the amplitude and phase of these signals, more information can be obtained within a single pulse.

[0042] Sweeping of individual frequencies over the same bandwidth as the frequencies in the pulses takes time. However, a single pulse with all frequency components can be sent and processed much faster than sweeps of individual frequencies covering the same range. Using a single short pulse provides the added benefit of not requiring additional sensing electrodes since reflections are transmitted back from the same electrodes used for energy delivery. In accordance with the present disclosure, these pulses can be applied before, during (randomly, intermittently, in response to user input, in response to sensed feedback, based on the state or stage of tissue treatment, between energy deliveries, etc.), and / or after energy delivery.

[0043] refer to Figure 1 , an electrosurgical system according to the present disclosure is shown as generally indicated by the reference numeral 2. The electrosurgical system 2 includes an electrosurgical clamp 10 and an electrosurgical generator 40. The electrosurgical clamp 10 is shown and described herein as a shaft-based, manual device. However, any other suitable electrosurgical clamp, whether shaft-based, hemostatic style, manual, partially electric, fully electric, robotic, etc., may be utilized in accordance with the present disclosure. Obviously, different relationships and considerations apply to each specific type of instrument; however, the aspects and features of the present disclosure regarding the treatment of tissue remain generally consistent with respect to any suitable instrument.

[0044] Continue to refer Figure 1, the clamp 10 includes a shaft 12, a housing 20, a handle assembly 22, a trigger assembly 25, a rotation assembly 28, and an end effector assembly 100. The shaft 12 has a distal portion 16 configured to mechanically engage the end effector assembly 100 and a proximal portion 14 that mechanically engages the housing 20. The cable 34 couples the clamp 10 to the electrosurgical generator 40 for transmitting energy and control signals between the generator 40 and the clamp 10. The cable 34 houses a plurality of wires 56 that are internally separated into wires 56a to 56c within the handle assembly 22 and / or within the shaft 12, which electrically interconnect the end effector assembly 100, the activation switch 30, and / or the generator 40 to each other.

[0045] The handle assembly 22 includes a movable handle 24 and a fixed handle 26. The fixed handle 26 is integrally connected to the housing 20, and the movable handle 24 is movable relative to the fixed handle 26. The movable handle 24 is ultimately connected to the drive assembly 70, and the two mechanically cooperate to move one or both of the jaw members 110, 120 of the end effector assembly 100 relative to the other between a spaced apart position and an approximated position to grasp tissue between these jaw members. Figure 1 As shown, the movable handle 24 is initially spaced apart from the fixed handle 26, and correspondingly, the jaw members 110, 120 are disposed in spaced apart positions (see also Figure 2A ). The movable handle 24 can be moved from this initial position to one or more compressed positions corresponding to one or more approximated positions of the jaw members 110, 120 (see Figure 2B ).

[0046] The drive assembly 70 can be configured to adjust the clamping force applied to tissue grasped between the respective surfaces 112, 122 of the jaw members 110, 120. More specifically, the handle assembly 22 and / or the latch assembly 27 in conjunction with the drive assembly 70 can be configured so that the jaw members 110, 120 apply a specific clamping force or a clamping force within a specific clamping force range to tissue grasped between the respective surfaces 112, 122 of the jaw members 110, 120. This can be achieved manually, for example, by moving the movable handle 24 from an initial position to a specific compressed position (multiple specific compressed positions) (e.g., a fully compressed position); via a mechanical latch, for example, where the latch assembly 27 is configured to latch the movable handle 24 in a specific position (or multiple specific positions); via an electric actuator with feedback-based control, for example, by driving or retracting a motor-controlled actuator to a specific position (or multiple specific positions); and / or via any other suitable structure. The drive assembly 70 in any of the configurations detailed above or any other suitable configuration may include one or more passive adjustment components (eg, springs, resilient features, etc.) and / or active adjustment components (eg, motors, manual drives, etc.).

[0047] Suitable mechanisms for use as drive assembly 70 or in combination with it for clamping force control include mechanisms described in U.S. Patent Nos. 5,776,130, 7,766,910, 7,771,426, and 8,226,650 and / or U.S. Patent Application Publication Nos. 2009 / 0292283, 2012 / 0172873, and 2012 / 0184988, all of which are incorporated herein by reference in their entirety. Other suitable mechanisms for applying a specific clamping force or a clamping force within a specific clamping force range to tissue captured between jaw members 110, 120 may also be provided. In the case where tissue is captured between jaw members 110, 120 at a specific clamping force or a clamping force within a specific clamping force range, energy may be supplied to either or both of the respective tissue contacting surfaces 112, 122 of jaw members 110, 120 to seal tissue, for example, via activation of activation switch 30.

[0048] The jaw clamping force measured at the midpoint along the length of the jaw members 110, 120 can be in the following range (or the jaw force range can be the following range): about 7.0 lbf to about 11.0 lbf; in other aspects, about 8.0 lbf to about 10.0 lbf; and in still other aspects, about 8.5 lbf to about 9.5 lbf.

[0049] A latch assembly 27 may be provided for selectively locking the movable handle 24 relative to the fixed handle 26 at various positions between the initial position and the compressed position to correspondingly lock the jaw members 110, 120 at various positions during pivoting, for example, at one or more approximate positions. The rotation assembly 28 may be rotated in either direction to similarly rotate the shaft 12 and the end effector assembly 100 relative to the housing 20.

[0050] Also refer to Figure 2A and Figure 2B , end effector assembly 100 is shown attached at distal end portion 16 of shaft 12 and includes opposing jaw members 110 and 120. Each jaw member 110, 120 includes conductive tissue contacting surfaces 112, 122, respectively, that cooperate to grasp tissue between the conductive tissue contacting surfaces, for example, in one or more approximated positions of jaw members 110, 120, and facilitate sealing of grasped tissue via conduction of energy from generator 40 between the conductive tissue contacting surfaces. More specifically, tissue contacting surfaces 112, 122 are electrically coupled to generator 40, for example, via wires 56a, 56b, and are configured to be energized to different electrical potentials so that radio frequency (RF) electrosurgical energy provided by generator 40 can be conducted between tissue contacting surfaces 112, 122 and via tissue grasped therebetween to seal the tissue. Tissue contacting surfaces 112, 122 may be defined by conductive plates secured to jaw members 110, 120, may be defined by surfaces of jaw members 110, 120 themselves, may be formed via deposition of material onto jaw members 110, 120, or may be defined and / or formed in any other suitable manner.

[0051] Either or both of the jaw members 110, 120 may further include one or more stop members 124 ( Figure 2A), the one or more stop members are disposed on or otherwise connected to either or both of the tissue contacting surfaces 112, 122 to maintain a minimum gap distance between the tissue contacting surfaces 112, 122 when the jaw members 110, 120 are disposed in a fully approximated position, thereby inhibiting electrical shorting. The stop member 124 can be insulated, partially insulated, and / or electrically isolated from either or both of the tissue contacting surfaces 112, 122. In various aspects, in the approximated position of the jaw members 110, 120, it is desirable to maintain the gap distance within a suitable gap distance range to ensure consistent and effective tissue sealing. The gap distance can be controlled by the stop member 124, the movable handle 24, the latch assembly 27, and / or the drive assembly 70, and in various aspects, can be about 0.001 inches to about 0.010 inches; in other aspects, about 0.001 inches to about 0.008 inches; and, in still other aspects, about 0.001 inches to about 0.006 inches. Other suitable gap distance ranges are also contemplated. The gap distance may be determined as the maximum gap distance between the tissue contacting surfaces 112, 122 at any point along the tissue contacting surfaces.

[0052] The activation switch 30 is disposed on the housing 20 and is coupled between the generator 40 and the tissue contact surfaces 112, 122 via the wire 56c or otherwise coupled to the generator and / or the tissue contact surface. The activation switch 30 can be selectively activated to start supplying energy from the generator 40 to the respective tissue contact surfaces 112, 122 of the jaw members 110, 120 of the end effector assembly 100. More specifically, the pressing of the activation switch 30 is recognized by the generator 40 (e.g., recognized as a decrease in resistance) to signal the generator 40 to start tissue sealing, such as supplying energy to the jaw members 110, 120.

[0053] The end effector assembly 100 is designed as a double-sided assembly, for example, wherein both the jaw member 110 and the jaw member 120 are movable relative to each other and relative to the shaft 12 about the pivot 19. However, the end effector assembly 100 may alternatively be configured as a single-sided assembly, for example, wherein one of the jaw members 110, 120 is fixed relative to the shaft 12 and the other jaw member 110, 120 is movable relative to the shaft 12 and the fixed jaw member about the pivot 19.

[0054] In some configurations, a knife assembly (not shown) is disposed within the shaft 12, and a knife channel 115 is defined within one or both jaw members 110, 120 to allow a blade (not shown) to reciprocate through the knife channel, for example, via actuation of the trigger assembly 25, to mechanically cut tissue captured between the jaw members 110, 120. In various aspects, the blade is energizable to achieve dynamic energy-based tissue cutting. Alternatively, the end effector assembly 100 may include, for example, a static energy-based tissue cutter (not shown) disposed in one or in one of the jaw members 110, 120. The energy-based cutter (whether static or dynamic) can be configured to supply any suitable energy to the tissue, such as RF, microwave, infrared, light, ultrasound, heat, etc., for energy-based tissue cutting. Energy activation for tissue cutting can be initiated via the trigger assembly 25, automatically after tissue sealing, via different (or another) activation of the switch 30, via an independent actuation button, via a foot switch (not shown), or in any other suitable manner.

[0055] Go to Figure 3 , a robotic surgical instrument provided in accordance with the present disclosure is shown, generally indicated by reference numeral 1000. Aspects and features of the robotic surgical instrument 1000 that are not germane to an understanding of the present disclosure are omitted to avoid obscuring aspects and features of the present disclosure with unnecessary detail.

[0056] The robotic surgical instrument 1000 comprises: a plurality of robotic arms 1002, 1003; a control device 1004; and an operating console 1005, which is coupled to the control device 1004. The operating console 1005 may comprise: a display device 1006, which may be arranged to display a three-dimensional image in particular; and manual input devices 1007, 1008, by means of which a surgeon can remotely manipulate the robotic arms 1002, 1003 in an operating mode. The robotic surgical instrument 1000 may be configured for a patient 1013 lying on a patient table 1012 to be treated in a minimally invasive manner. The robotic surgical instrument 1000 may further comprise a database 1014, in particular coupled to the control device 1004, or capable of accessing the database, in which, for example, preoperative data and / or anatomical maps of the patient 1013 are stored.

[0057] Each of the robotic arms 1002, 1003 may include a plurality of members connected by joints and attachment devices 1009, 1011 that may be attached to, for example, end effector assemblies 1100, 1200, respectively. For example, the end effector assembly 1100 may be similar to the end effector assembly 100 ( Figures 1 to 2B) and including any features thereof, and together with the robotic arm 1002, functions similarly to that detailed above with respect to the clamp 10, except that it functions in a robotically actuated and controlled manner. Other suitable end effector assemblies for coupling to the attachment device 1009 are also contemplated. The end effector assembly 1200 can be any end effector assembly, such as a surgical camera, other surgical tools, etc. The robotic arms 1002, 1003 and the end effector assemblies 1100, 1200 can be driven by an electric drive (e.g., a motor) connected to the control device 1004. The control device 1004 (e.g., a computer) can be configured to enable the motor, in particular by means of a computer program, in such a way that the robotic arms 1002, 1003, their attachment devices 1009, 1011, and the end effector assemblies 1100, 1200 perform the desired movement and / or function, respectively, according to the corresponding input from the manual input devices 1007, 1008. The control device 1004 may also be configured in such a way that it regulates the movement of the robotic arms 1002 , 1003 and / or the motors.

[0058] refer to Figure 4 , the generator 40 may be configured for use with the clamp 10 ( Figure 1 )、Robotic Surgery System 1000( Figure 3 ) and / or any other suitable surgical instrument or system. Generator 40 includes sensor circuitry 42, controller 44, high voltage direct current DC power supply ("HVPS") 47, and RF output stage 48. HVPS 47 provides high voltage DC power to RF output stage 48, which converts the high voltage DC power into RF energy for delivery to an end effector assembly, such as respective tissue contacting surfaces 112, 122 ( Figures 1 to 2B ). In particular, the RF output stage 48 generates a sinusoidal waveform of high frequency RF energy. The RF output stage 48 is configured to generate a plurality of waveforms having various duty cycles, peak voltages, crest factors, and other parameters depending on the particular mode of operation.

[0059] The controller 44 includes a microprocessor 45 operably connected to a memory 46, which may be a volatile memory (e.g., RAM) and / or a non-volatile memory (e.g., flash media, disk media, etc.). The microprocessor 45 is operably connected to the HVPS 47 and / or the RF output stage 48, thereby allowing the microprocessor 45 to control the output of the generator 40, for example, based on feedback received from the sensor circuit system 42. The sensor circuit system 42 is operably coupled to the wires 56a, 56b that transmit signals to / from the tissue contacting surfaces 112, 122 ( Figures 1 to 2B) supply energy. Sensor circuit system 42 can determine one or more parameters from wires 56a, 56b and more specifically the signals transmitted along them, such as tissue impedance, output current and / or voltage, etc. Sensor circuit system 42 provides feedback based on the sensed parameters, for example, to controller 44, which in turn selects an energy delivery algorithm, modifies the energy delivery algorithm, and / or adjusts the energy delivery parameters based on the feedback. Sensor circuit system 42 or controller 44 can also monitor wire 56c to determine whether switch 30 ( Figure 1 ) is activated (and / or deactivated), thereby starting (or terminating) energy supply based thereon in response thereto.

[0060] refer to Figure 5 , System 2 ( Figure 1 ) shows the generator 40 connected to the jaw members 110, 120 by the cable 34. A signal, such as a pulse 502, is transmitted on the cable 34. The signal travels at a speed that is a function of the characteristic impedance of the cable 34. For example, the characteristic impedance of the cable can be 50 ohms. However, any suitable characteristic impedance can be used. The time it takes for the signal to travel the length of the cable (e.g., about 150 nS for a 10 foot cable) is the speed per unit length divided by the physical length of the cable. The time to travel the length of the cable is referred to as the electrical length "L". If the duration of the signal (i.e., the pulse 502) is shorter than the electrical length "L" of the cable, then after the generator 40 completes the transmission, a reflection will be transmitted back to the generator 40. This implements a time discrimination scheme, wherein the receiver at the generator output is turned off during the time the signal is being transmitted (i.e., the pulse width), and turned on during the time required for the signal to travel the length of the cable 34 and back.

[0061] To measure properties of the tissue (and / or other material) between jaw members 110, 120, such as impedance, a short duration pulse may be transmitted down instrument cable 34 and the reflected signal returned measured. While impedance is used as an example, other properties are also contemplated.

[0062] The difference between the characteristic impedance of the grasped tissue (and / or other material) and the characteristic impedance of the cable 34 and the generator 40 will cause reflections of the signal (i.e., pulse 502). The impedance between the jaw members 110, 120 will reflect some of the signal (i.e., reflected pulse 506) back to the generator 40. The amount of reflection is a function of the impedance between the jaw members 110, 120 and the characteristic impedance of the cable 34. The characteristic impedance of the cable 34 is relatively constant, so changes in the amplitude of the reflected signal are directly related to the impedance between the jaw members 110, 120. In various aspects, the voltage standing wave ratio (VSWR) mismatch between the grasped tissue and the characteristic impedance of the system (e.g., 50 ohms) can be determined from the amplitude of the reflected signal. The resulting VSWR can be used to determine tissue impedance in and around the jaw members 110, 120 (and thereby determine tissue type, tissue thickness, tissue moisture, etc.) and / or other conditions, such as whether the jaw members 110, 120 are immersed in saline, whether conductive materials are nearby, whether an open circuit or short circuit condition exists, etc.

[0063] Impedance (and / or other properties) can be derived from time domain voltage measurements of the amplitude of the reflected pulse. Impedance can also be derived from changes in the frequency spectrum and / or frequency domain measurements. In various aspects, the impedance, phase, and / or amplitude at more than one frequency of the returned signal can be measured and used to determine tissue properties. More specifically, measuring the impedance, phase, and / or amplitude at multiple frequencies of the returned signal provides a feedback spectrum of, for example, impedance, thereby allowing tissue properties to be determined based not only on singular impedance measurements but also on relative impedance measurements at different frequencies. This can be achieved with phase, amplitude, and / or time.

[0064] Figure 6 A flow chart of an exemplary computer-implemented method for sealing tissue is shown. Figure 6 The steps of the present invention are shown in a specific order, but these steps need not all be performed in the specified order, and some steps can be performed in another order. In various aspects, Figure 6 The operation can be performed in whole or in part by Figure 4 The controller 44 of the generator 40 performs. In various aspects, Figure 6 The operations of may be performed in whole or in part by another device (eg, a mobile device and / or a client computer system). Such variations are considered to be within the scope of the present disclosure.

[0065] First, in step 602, the tissue is grasped between the first jaw member 110 and the second jaw member 120 ( Figure 5 )between.

[0066] Next, at step 604, the controller 44 applies a signal to the grasped tissue in anticipation of tissue treatment. The signal is based on a tissue sensing algorithm. For example, the signal may include a short pulse having an amplitude of about 500 mV and a pulse duration of about 100 nS. The signal is configured to be reflected back from the first jaw member 110 and the second jaw member 120 via the cable 34. The tissue sensing algorithm may include the amplitude of the signal, the duration of the signal, and / or the repetition rate of the signal.

[0067] Next, at step 606, the controller 44 receives reflected signals from the first jaw member 110 and the second jaw member 120. For example, the reflected signals may have an amplitude of approximately 30 mV.

[0068] Next, at step 608, the controller 44 determines tissue characteristics and / or other conditions based on the reflected signal. For example, the controller 44 can determine that the tissue is a specific type of tissue, such as a blood vessel, muscle, organ, etc., based on the reflected signal. The determined tissue type can be used to select and / or adjust a tissue sealing algorithm or to allow or prevent subsequent application of energy. The impedance of the tissue (or the impedance spectrum of the tissue at multiple frequencies of the reflected signal) can be used to determine the tissue type.

[0069] The delay time and / or voltage of the reflected signal can additionally or alternatively facilitate determining tissue characteristics, such as tissue type. In various aspects, other tissue characteristics, such as tissue thickness, tissue moisture content, tissue conductivity, etc., can be determined based on the impedance of the tissue (or the impedance spectrum of the tissue at multiple frequencies of the reflected signal).

[0070] The controller 44 may determine the tissue characteristics based on determining the frequency content of the reflected signal, and then determine the tissue characteristics based on the determined frequency content of the reflected signal. A fast Fourier transform (FFT) may be performed on the reflected signal (e.g., a reflected pulse). An ideal short pulse has an infinite series of harmonics of equal amplitude. In practice, due to the rising edge of the generated pulse and due to various parasitic capacitances and / or inductances, the harmonic series is not infinite and decays as its frequency rises. For a known short pulse with a known duration, an FFT may be performed to determine an initial frequency domain response. The controller 44 may perform an FFT on the received reflected signal to determine the frequency domain response of the reflected pulse. The controller 44 may compare the initial frequency domain response with the reflected frequency domain response and determine the tissue characteristics based on the comparison.

[0071] In various aspects, the controller 44 can adjust the tissue sealing algorithm based on the determined tissue characteristics. More detailed tissue sealing algorithms suitable for use in accordance with the present disclosure can be found, for example, in U.S. Patent No. 8,920,421, entitled "SYSTEM AND METHOD FOR TISSUE SEALING," filed on November 29, 2010 as U.S. Patent Application No. 12 / 995,042, the entire contents of which are hereby incorporated herein by reference; and U.S. Patent No. 8,147,485, entitled "SYSTEM AND METHOD FOR TISSUE SEALING," filed on February 23, 2009 as U.S. Patent Application No. 12 / 391,036, the entire contents of which are hereby incorporated herein by reference.

[0072] In yet other aspects, a tissue sensing algorithm may additionally or alternatively be performed during and / or after a tissue sealing algorithm.

[0073] In various aspects, the controller 44 can apply energy to the grasped tissue to seal the grasped tissue according to a tissue sealing algorithm. The tissue sealing algorithm can be independent of the tissue sensing algorithm, or the tissue sensing algorithm can be integrated into the tissue sealing algorithm. In various aspects, the tissue sensing algorithm is controlled in a first manner and the tissue sealing algorithm is controlled in a different second manner.

[0074] In various aspects, controller 44 can apply signals to determine changes in tissue properties during treatment of tissue.At least a portion of a tissue sealing algorithm can adjust energy output to track impedance versus time trajectory.

[0075] In various aspects, controller 44 may determine whether the tissue sensing algorithm is complete before applying energy to the grasped tissue according to the tissue sealing algorithm.

[0076] After applying energy to the grasped tissue according to the tissue sensing algorithm and before applying energy to the grasped tissue according to the tissue sealing algorithm, the controller 44 may implement a delay period in which no energy is applied.

[0077] Figure 7 A simulation of a signal (i.e., pulse 502) having a duration of 150 nS and a 150 nS delay between reflection and measured reflected pulse 506 is shown. The impedance of the load that the pulse is reflected off of is varied from 1 ohm to 1000 ohms. The simulation demonstrates how the amplitude of the returned pulse changes as the impedance changes.

[0078] refer to Figure 8, provides an oscilloscope trace showing a transmitted signal (ie, pulse 502) and a reflected signal (ie, reflected pulse 506), wherein Figure 5 The first jaw member 110 and the second jaw member 120 are in the open position and not grasping tissue. As can be seen in the oscilloscope trace, the applied signal is a pulse of about 60 nS duration and about 400 mV peak amplitude. The length of the cable provides a delay of about 10 nS. In the case of an "ideal" open circuit, the amplitude of the reflected pulse 506 would be equal to the amplitude of the transmitted pulse 502. The observed reflected pulse 506 shows Figure 5 The first jaw member 110 and the second jaw member 120 have an impedance other than the characteristic impedance of 50 ohms. Therefore, in addition to detecting tissue characteristics, other conditions associated with the first jaw member 110 and the second jaw member 120 can also be detected, such as an open circuit condition. Similarly, it can be determined whether a sufficient volume of tissue is captured between the first jaw member 110 and the second jaw member 120, or whether a very small volume of tissue is captured that is insufficient to establish a proper tissue seal. Further, the presence of other materials (e.g., bone, staples, other instruments, etc.) can also be detected.

[0079] Fig. 9 Oscilloscope traces showing a transmitted pulse 502 and a reflected pulse 506 entering an impedance of approximately 100 ohms are shown. Fig.10 A simulation of an ideal reflected pulse from a 100 ohm load is shown. Fig. 9 As can be seen from the oscilloscope trace, the amplitude of the reflected pulse 506 is close to Fig.10 The simulated theoretical amplitude is about 138 mV peak.

[0080] Fig.11 An oscilloscope trace showing a transmitted pulse 502 and a reflected pulse 506 is shown, where Figure 5 The first and second jaw members 110, 120 of the embodiment of FIG. 1 are gripping a load of approximately 50 ohms. Based on the oscilloscope trace, the amplitude of the reflected pulse 506 is close to the theoretical amplitude of approximately zero volts peak for a 50 ohm system. The characteristic impedance of the coaxial cable is 50 ohms, so there should be almost zero reflected signal. The actual reflected pulse 506 trace shows that due to Figure 5 The voltage is close to zero volts at the end of the pulse due to the parasitic capacitance and inductance of the first jaw member 110 and the second jaw member 120.

[0081] refer to Figure 12 to Figure 14 , showing a short circuit between the first jaw member 110 and the second jaw member 120 ( Fig.12 ),open circuit( Fig.13 ) and 50 ohm impedance ( Fig.14) are frequency domain graphs of the frequency domain responses of the transmitted pulse 502 and the reflected pulse 504 for three exemplary impedance conditions. Figure 5 The first and second jaw members 110, 120 apply a short pulse 502 having a duration of about 60 nS and a very low amplitude of about 40 mV peak, and the frequency spectrum is shown.

[0082] These results show that the spectrum is different for different conditions. Two frequencies were selected to show the changes. The markers were placed at about 6.19 MHz and about 10.19 MHz. The amplitude changes at these two frequencies can be seen, as summarized in the table below.

[0083] The results show that the spectrum does change with impedance, showing that the frequency domain or frequency response to a short pulse can be used to determine impedance changes and distinguish tissue types and / or other tissue characteristics.

[0084] Fig.12 It shows Figure 5 The frequency spectrum of a short circuit between the first clamping jaw member 110 and the second clamping jaw member 120 is depicted. Fig.13 is a trace showing a frequency spectrum with an open circuit between the first jaw member 110 and the second jaw member 120 . Fig.14 is a trace of a frequency spectrum showing the first jaw member 110 and the second jaw member 120 grasping a load of approximately 50 ohms.

[0085] Fig.15 It shows the Figure 12 to Figure 14 Table of impedance versus amplitude for different frequencies of the return pulse for the load conditions shown. Fig.12 With the short circuit load shown, an amplitude of approximately -56 dBm was measured at approximately 6.19 MHz. An amplitude of approximately -74 dBm was measured at approximately 10.19 MHz. Fig.13 With an open load, at about 6.19 MHz, an amplitude of about -78 dBm was measured. At about 10.19 MHz, an amplitude of about -58 dBm was measured. Fig.14 With a 50 ohm load, at about 6.19 MHz, an amplitude of about -58 dBm was measured. At about 10.19 MHz, an amplitude of about -64 dBm was measured.

[0086] Although several aspects of the disclosure have been shown in the accompanying drawings, it is not intended to limit the disclosure thereto, as it is intended that the scope of the disclosure be as wide as the art will allow, and the specification should be read in the same manner. Therefore, the above description should not be construed as limiting, but merely as an illustration of a particular configuration. Those skilled in the art will envision other modifications within the scope and spirit of the appended claims.

Claims

1. A method for treating tissue, the method comprising: grasping tissue between the first jaw member and the second jaw member; applying a signal to the grasped tissue in anticipation of tissue treatment based on a tissue sensing algorithm; receiving reflected signals from the first jaw member and the second jaw member at a plurality of frequencies; as well as A tissue characteristic or condition at the first jaw member and the second jaw member is determined based on the reflected signal. 2 . The method of claim 1 , further comprising adjusting a tissue sealing algorithm based on the determined tissue characteristics.

3. The method of claim 1, further comprising applying energy to the grasped tissue to seal the grasped tissue according to a tissue sealing algorithm, wherein The tissue sealing algorithm is independent of the tissue sensing algorithm.

4. The method according to claim 1, wherein: The tissue sensing algorithm is controlled in a first manner and the tissue sealing algorithm is controlled in a second, different manner.

5. The method according to claim 1, wherein: The delay times and / or voltages of the reflected signals at the multiple frequencies are used to determine the tissue characteristics.

6. The method according to claim 5, wherein: The tissue characteristic is impedance at each of the plurality of frequencies.

7. The method according to claim 1, wherein: At least a portion of the tissue sealing algorithm adjusts energy output to track the impedance versus time trajectory.

8. The method according to claim 1, wherein: The condition at the first jaw member and the second jaw member is one of an open circuit condition or a short circuit condition.

9. The method according to claim 1, wherein: Determining the tissue characteristics includes: determining a frequency content of the reflected signal; and A tissue property is determined based on the determined frequency content of the reflection signal.

10. The method according to claim 1, further comprising: After applying energy to the grasped tissue according to the tissue sensing algorithm and before applying the energy to the grasped tissue according to the tissue sealing algorithm, a delay period in which no energy is applied is implemented.

11. An electrosurgical system for treating tissue, the electrosurgical system comprising: an electrosurgical clamp comprising a first jaw member and a second jaw member; as well as An electrosurgical generator, the electrosurgical generator comprising: Processor; and a memory comprising instructions stored on the memory that, when executed by the processor, cause the system to: applying a signal based on a tissue sensing algorithm to tissue grasped between the first jaw member and the second jaw member in anticipation of tissue treatment; receiving reflected signals from the first jaw member and the second jaw member at a plurality of frequencies; and A tissue characteristic or condition at the first jaw member and the second jaw member is determined based on the reflected signal.

12. An electrosurgical system according to claim 11, wherein: The instructions, when executed by the processor, further cause the system to adjust a tissue sealing algorithm based on the determined tissue characteristics.

13. The electrosurgical system of claim 11, wherein: The instructions, when executed by the processor, further cause the system to apply energy to the pre-treatment grasped tissue to seal the pre-treatment grasped tissue according to a tissue sealing algorithm, wherein the tissue sealing algorithm is independent of the pre-treatment algorithm.

14. The electrosurgical system of claim 11, wherein: The instructions, when executed by the processor, further cause the system to control the tissue sensing algorithm in a first manner, and the tissue sealing algorithm to be controlled in a second, different manner.

15. The electrosurgical system of claim 11, wherein: The delay times and / or voltages of the reflected signals at the multiple frequencies are used to determine the tissue characteristics.

16. An electrosurgical system according to claim 15, wherein: The tissue characteristic is impedance at each of the plurality of frequencies.

17. The electrosurgical system of claim 11, wherein: At least a portion of the tissue sealing algorithm adjusts energy output to track the impedance versus time trajectory.

18. The electrosurgical system of claim 11, wherein: The condition at the first jaw member and the second jaw member is one of an open circuit condition or a short circuit condition.

19. The electrosurgical system of claim 11, wherein: When determining the tissue characteristic, the instructions, when executed by the processor, further cause the system to: determining a frequency content of the reflected signal; and A tissue property is determined based on the determined frequency content of the reflection signal.

20. A non-transitory computer readable medium storing instructions that, when executed by a processor, cause the processor to perform a computer-implemented method of treating tissue, the method comprising: grasping tissue between the first jaw member and the second jaw member; applying a signal to the grasped tissue in anticipation of tissue treatment based on a tissue sensing algorithm; receiving reflected signals from the first jaw member and the second jaw member at a plurality of frequencies; as well as A tissue characteristic or condition at the first jaw member and the second jaw member is determined based on the reflected signal.

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