Rupture detection in bipolar electrosurgical instrument sheath

Abstract

The invention relates to rupture detection in a bipolar electrosurgical instrument sheath. The present application provides a system for detecting a rupture of an insulating sheath in a bipolar electrosurgical instrument, the system comprising: a first pulse detection circuit for detecting a first high frequency (HF) signal component of an HF signal conducted on a lead of the bipolar instrument; a second pulse detection circuit for detecting a second HF signal component of the HF signal conducted on the conductive shield surrounding the lead; a magnitude difference sampling logic to generate a sampled value indicative of a magnitude difference between the first HF signal component and the second HF signal component; and current detection logic to detect a current between the shield and the anatomical tissue based on the sampled values.

Description

[0001] This application is a divisional application of Chinese patent application 202080032020.0 (PCT / US2020 / 020413) filed on February 28, 2020 and entitled “Breakage Detection in a Bipolar Electrosurgical Instrument Sheath”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Provisional Patent Application No. 62 / 812,731, filed on March 1, 2019, which is incorporated herein by reference in its entirety. Background Art

[0004] Electrosurgery involves the use of electricity to cause thermal destruction of biological tissue, such as to cut or remove tissue by drying, coagulation or vaporization. Benefits include the ability to make precise cuts with limited blood loss. Electrosurgical instruments are often used during surgical procedures to help prevent blood loss in hospital operating rooms or outpatient surgeries. The two most commonly used electrosurgical procedures are high-frequency electrosurgery and electrocautery. High-frequency electrosurgery involves high-frequency (radio frequency) alternating current, which is converted into heat by resistance as it passes through tissue. Heat accumulation within the tissue causes thermal tissue damage, such as causing incisions or ablation. Electrocautery also involves direct heat transfer to tissue. However, instead of passing an electric current through the tissue, an electric current is used to heat a handheld element, which is then applied to the tissue. Additional modalities of electrosurgery include electrolysis, which uses a chemical reaction produced by direct current to damage tissue; and cryoablation, which uses an electric current to ionize a conductive medium such as isotonic saline, which is then used to transfer heat to the tissue.

[0005] Bipolar and monopolar are examples of two modes of energy delivery during electrosurgery. Monopolar electrosurgery involves passing current from a probe electrode to patient tissue and through the patient tissue to a return pad to complete the current circuit. Bipolar electrosurgery typically involves passing current through only a portion of the patient tissue disposed between the two arms of the forceps electrodes. The conductive leads of a bipolar instrument are surrounded by a conductive safety shield, which is surrounded by a non-conductive outer insulating sheath.

[0006] In electrosurgery, it is common for an active monopolar energy instrument to contact an electrode of a nearby bipolar instrument and transfer energy to the bipolar instrument arm, particularly when the bipolar instrument may also be used for mechanical grasping. Such contact may be accidental or intentional, for example, some surgeons are taught to "buzz" a bipolar grasper with monopolar energy to produce a hemostatic effect. When this occurs, the monopolar energy may travel through the bipolar instrument arm and become capacitively coupled to the shield of the bipolar instrument. If this monopolar energy is coupled to the bipolar instrument and the insulating sheath of the bipolar instrument suffers a rupture, an alternative abnormal current path is created that includes the shield. For example, a typical bipolar instrument operates at a voltage in the range of about 60Vp-500Vp, and a typical monopolar instrument operates at a voltage in the range of about 300Vp-3,000Vp. Therefore, this abnormal current path has the potential to cause unintended patient burns to patient tissue at the location of the sheath rupture. Summary of the invention

[0007] In one aspect, a system detects a rupture of an insulating sheath in a bipolar electrosurgical instrument. The system includes a first pulse detection circuit for detecting a first HF signal component of an HF signal conducted on a lead, and includes a second pulse detection circuit for detecting a second HF signal component of the HF signal conducted on a shield. Phase difference sampling logic generates a sampled value indicating a phase difference between the first HF signal component and the second HF signal component. Current detection logic detects a current between the shield and anatomical tissue based on the sampled value.

[0008] In another aspect, a method for detecting a rupture of an insulating sheath in a bipolar electrosurgical instrument is provided. The method includes detecting pulses of a first HF signal component of an HF signal conducted on a lead, and detecting pulses of a second HF signal component of the HF signal conducted on a shield. Sampled values ​​are generated indicating a phase difference between pulses of the first HF signal component and the second HF signal component. Current between the shield and anatomical tissue is detected based on the sampled values.

[0009] In another aspect, a system detects a rupture of an insulating sheath in a bipolar electrosurgical instrument. The system includes a first pulse detection circuit for detecting a first HF signal component of an HF signal conducted on a lead, and includes a second pulse detection circuit for detecting a second HF signal component of the HF signal conducted on a shield. Magnitude difference sampling logic generates sampled values ​​indicating a magnitude difference between the first HF signal component and the second HF signal component. Current detection logic detects current between the shield and anatomical tissue based on the sampled values.

[0010] In another aspect, a method for detecting a rupture of an insulating sheath in a bipolar electrosurgical instrument is provided. The method includes detecting pulses of a first HF signal component of an HF signal conducted on a lead, and detecting pulses of a second HF signal component of the HF signal conducted on a shield. Sampled values ​​are generated indicating a magnitude difference between the pulses of the first HF signal component and the second HF signal component. Current between the shield and anatomical tissue is detected based on the sampled values.

[0011] The scope of the present invention is defined by the claims, which are incorporated into this section by reference. By considering the following detailed description of one or more examples, those skilled in the art will more completely understand the examples of the present invention and realize their additional advantages. Reference will be made to the accompanying drawings, which are first briefly described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Examples of the present invention and its advantages can be best understood by referring to the detailed description and the accompanying drawings together. It should be understood that similar reference numerals are used to identify similar elements shown in one or more figures. It should also be recognized that these drawings are not necessarily drawn to scale.

[0013] Figure 1 is a schematic diagram illustrating an example bipolar surgical electrosurgical instrument and an example monopolar surgical electrosurgical instrument that are selectively coupled to receive electrosurgical signals from an electrosurgical generator unit.

[0014] Figure 2A is a schematic axial cross-sectional view of a bipolar lead cable.

[0015] Figure 2B is a schematic longitudinal cross-sectional view of a bipolar lead cable with an intact outer sheath.

[0016] Figure 2C is a schematic longitudinal cross-sectional view of a bipolar lead cable with a ruptured outer sheath.

[0017] Figure 3A is a schematic physical model representing the electrical contact points between an activated monopolar end effector and a bipolar end effector.

[0018] Figure 3B Yes means Figure 3A A schematic circuit model of the physical model of .

[0019] Figure 4A-4B It indicates that during the electrical contact between the activated monopolar end effector and the bipolar end effector, when the insulating sheath is intact ( Figure 4A ) and when the sheath is broken ( Figure 4BSchematic block diagram of an example monitoring system coupled to a bipolar ESI to monitor characteristics of a high frequency (HF) signal component parasitically coupled to a shield conductor.

[0020] Figure 5 is an illustrative schematic diagram showing details of a first example monitoring circuit that detects an RF signal phase shift change event.

[0021] Figure 6 is a schematic flow chart diagram representing a monitoring process for monitoring the phase relationship between a first HF monopolar signal component and a second HF monopolar signal component to detect the presence of a current in a patient's tissue indicative of a breached insulating sheath.

[0022] Figure 7 It is shown in Figure 6 Schematic signal diagram of example signals generated by a first example monitoring circuit during a process of.

[0023] Figure 8 is an illustrative schematic diagram showing details of a second example monitoring and detection circuit for detecting HF signal magnitude or phase change events. DETAILED DESCRIPTION

[0024] Electrosurgical instruments

[0025] Figure 11 is a schematic diagram showing an example bipolar surgical electrosurgical instrument 102 and an example monopolar surgical electrosurgical instrument 104 that are selectively coupled to receive electrosurgical signals from an electrosurgical generator unit (ESU) 106. The electrosurgical signal is typically a high frequency signal (HF), typically in the radio frequency range (RF) whose voltage level is suitable for achieving a desired surgical effect (e.g., desiccation, coagulation, or vaporization of patient tissue 130). The voltage level of the electrosurgical signal is selected based on the desired surgical effect. A first electrosurgical instrument (ESI) 102 includes a first end effector 108, which includes a first jaw member 110 including a first electrode 112 and a second jaw member 114 including a second electrode 116. A second ESI 104 includes a second end effector 118, which includes a single electrode, namely a monopolar electrode 120. A bipolar lead cable 122 includes a first bipolar lead and a second bipolar lead extending between the ESU and the bipolar end effector 108. A first bipolar lead within cable 122 is electrically coupled to a first electrode 112 within a first arm 110 of a bipolar end effector 108. A second bipolar lead within cable 122 is electrically coupled to a second electrode 116 within a second arm 114 of the bipolar end effector 108. A monopolar lead cable 124 extends between the ESU 106 and the monopolar instrument 104. Monopolar current is passed through monopolar electrical lead 124-1 to monopolar electrode 120 and then through patient tissue 130-2 to a return conductor pad 128 placed in contact with patient tissue 130, which provides a return path for the monopolar current to return to the ESU 106 through 126. Commonly assigned U.S. Provisional Patent Application Serial No. 62 / 513,287, entitled “Electrosurgical Output Stage with Integrated DC Regulator,” filed on May 31, 2017, describes an ESU 106 according to some embodiments and is expressly incorporated herein in its entirety by this reference.

[0026] The end effector 108 of the bipolar ESI 102 includes an articulated jaw including a first jaw member 110 and a second jaw member 114 that are articulated relative to each other about a pivot axis 132. At least one of the first jaw member 110 and the second jaw member 114 is mounted to rotationally pivot about the pivot axis 132 between an open position in which the first jaw 110 and the second jaw 114 are spaced apart from each other and a closed position for grasping biological tissue 130-1 therebetween. A first electrode 112 and a second electrode 116 are mounted on the jaw members 110, 114 to electrically contact the biological tissue 130-1 grasped between the first jaw member 110 and the second jaw member 114. For example, during normal operation, when the jaw members 110, 114 grasp tissue 130-1 therebetween, the ESU 106 applies a high-frequency electrosurgical signal between the first electrode 112 and the second electrode 116 to cause current to flow through the tissue portion 130-1 grasped between the jaw members 110, 114 so as to apply heat to the first tissue portion 130-1, thereby applying an electrosurgical effect (e.g., desiccation, coagulation, or vaporization).

[0027] The end effector 118 of the monopolar ESI 104 includes a single third electrode 120 that can be placed in contact with a patient's biological tissue 130-2. During normal operation, the ESU 106 applies a high-frequency electrosurgical signal between the third electrode 120 and the return conductor pad 128 to cause current to flow through a second tissue portion 130-2 disposed between the third electrode 120 and the return conductor pad 128, thereby causing current to flow through the second tissue portion 130-2 to apply an electrosurgical effect to the second tissue portion 130-2. The return conductor pad 128 has a sufficiently large surface area so that the patient tissue in physical contact with the pad has a sufficiently large surface area so that the return current to the ESU 106 spreads over a sufficiently wide patient tissue area 130 to sufficiently limit the current density, thereby avoiding, for example, tissue burns or other trauma caused by the return current.

[0028] The bipolar ESI 102 generally uses a lower voltage and therefore lower energy than the monopolar second ESI 104. Due to the lower energy level, the bipolar ESI 102 may have a more limited ability to cut and coagulate large bleeding areas and is more ideal for use in those procedures where the first biological tissue portion 102 can be easily grasped on both sides by the jaw members 110, 114 including the first electrode 112 and the second electrode 116. Therefore, in bipolar surgery, the electrosurgical current in the patient is limited to the tissue between the jaw electrodes 112, 116, which can provide better control of the target area and help prevent damage to other sensitive tissues.

[0029] Bipolar lead cable 122 and monopolar lead cable 124 span the distance between ESU 106 and respective bipolar ESI 102 and monopolar ESI 104. Bipolar lead cable 122 includes outer insulating sheath 122S, which may include insulating material encapsulating first conductive bipolar lead 122-1 and second conductive bipolar lead 122-2 (commonly referred to as "electrodes") extending therein. Monopolar lead cable 124 includes cable outer sheath 124S, which may include insulating material encapsulating third conductive monopolar lead 124-1 extending therein.

[0030] The ESU 106 includes a first transformer circuit 140 for selectively coupling electrosurgical signals between a first bipolar lead 122-1 and a second bipolar lead 122-2 (also referred to as an active lead and a return lead). The ESU 106 controllably electrically couples and decouples respective first and second terminals 146, 148 of the first transformer 140 to and from respective first and second bipolar leads 122-1, 122-2. The ESU 106 includes a second transformer circuit 150 for selectively coupling electrosurgical signals between the monopolar lead 124-1 and the third (return) conductor cable 126. More specifically, the ESU 106 is configured to controllably electrically couple and decouple first and second terminals 156, 158 of the second transformer 150 to the third monopolar lead 124-1 and the third (return) conductor cable 126 at the proximal portion 124P of the second cable 124, respectively.

[0031] Parasitic capacitance in bipolar leads

[0032] Figure 2A is a schematic axial cross-sectional view of bipolar lead cable 122 . Figure 2B is a schematic longitudinal cross-sectional view of a bipolar lead cable 122 with an intact outer sheath 124S. Figure 2C2 is a schematic longitudinal cross-sectional view of a bipolar lead cable 122 with a ruptured 210 outer sheath 122S. The bipolar lead cable 122 includes an elongated tubular shield conductor 212 surrounded by a non-conductive tubular outer insulating sheath 122S. The shield 212 surrounds the first and second (active and return) bipolar leads 122-1, 122-2 to provide protection, thereby preventing accidental parasitic capacitive coupling of monopolar electrosurgical energy from the bipolar leads 122-1, 122-2 to the patient. Capacitively coupled energy can potentially cause arcing or conduction to the patient's tissue 130 that may cause thermal damage to the patient. The parasitic capacitance 216 between the shield 212 and the bipolar leads 122-1, 122-2 allows monopolar energy to be accidentally transferred from the ESI 104 to the bipolar leads 122-1, 122-2 and the shield 212. The insulating sheath 122S electrically isolates the capacitively coupled conductor shield 212 from the patient tissue 130. A dielectric material 214 is disposed between the shield 212 and the first bipolar lead 122-1 and the second bipolar lead 122-2 and between the first bipolar lead and the second bipolar lead itself. Figure 2C ) may occur due to accidental or aggressive use during a surgical procedure, such as when another instrument (not shown) physically contacts bipolar lead cable 122 during a surgical procedure.

[0033] Abnormal current flow due to a break in the insulating sheath

[0034] Figure 3A is a schematic physical model representing the electrical contact point 302 between the activated monopolar end effector 118 and the bipolar end effector 108. A high frequency (HF) monopolar current I applied to the bipolar instrument lead M Parasitic coupling to the protective shield. Impedance R including patient tissue impedance total The shield is electrically coupled back to pad 128, which is electrically coupled to the ESU (not shown). M From the monopolar electrode 120 to the bipolar jaw electrode 116 (or 112), to one or both of the bipolar leads 122-1 and 122-2, to the shield 212, to the electrode having an impedance R total Path, to the return lead (not shown). Typically, the unipolar signal components on the two bipolar leads have matching phase and magnitude. As explained more fully below, if the sheath 122S is intact, then R total Including the patient's tissue impedance (R P ) plus the impedance of the insulation sheath resistance (R sh ). However, if the sheath 122S is broken, R total The impedance of the patient's tissue only (R P ).

[0035] Figure 3B Yes means Figure 3A A simplified schematic circuit model of the physical model of the circuit includes a unipolar voltage source (V M ), parasitic coupling capacitance C P and the path impedance Rtotal between the shield and the return pad, which includes the patient tissue. The bipolar lead node 320 is coupled to V m and C p The bipolar shield node 330 is coupled between C p and Rtotal. Unipolar current I M Flow within the circuit model. When the insulating sheath is broken (i.e., there is no sheath resistance), Rtotal is primarily due to the patient resistance, which is primarily resistive and typically measured in the thousands of ohms range. When the insulating sheath is intact, Rtotal is primarily due to the sheath resistance, which is typically measured in the range of about 1 M ohms or greater.

[0036] Z equivalent =R total -j*X C

[0037] Z equivalent is the total impedance of the branch: the impedance resulting from the combination of Xc and RTotal. When the sheath is intact, Rtotal includes the sheath resistance (Rsh) and the patient resistance (Rp) in the total impedance of the branch. In this case, the resistance of the branch is much larger than the reactance because when the sheath is intact, Rtotal>>Xc. Therefore, the resistivity of the branch is much larger than the reactance, and the current through the branch causes the voltage to drive the current through the branch by a small amount. This causes a small phase shift in the voltage between 320 and 330. 320 is the bipolar electrode and 330 is the bipolar shield. These are the electrical points where we measure the phase shift.

[0038] When a sheath breach occurs, meaning that the shaft of the bipolar instrument is in direct contact with the patient, the sheath resistance, Rsh, is not included in the Rtotal of the model. When this occurs, the resistance is on the same order of magnitude as the reactance, and the total impedance of the branch becomes more reactive than when an intact sheath is present. The current through the branch now causes the drive voltage to be a larger amount than when an intact sheath is present. The forward shift of the current through the branch creates a larger voltage phase shift between 320 and 330. These are the electrical points at which we measure the phase shift. We set the phase shift threshold to ensure that if it is crossed, there must be a sheath breach. It should be understood that Rtotal is at the I at the bipolar lead node 320. M The current component is coupled to the parasitic coupling I MWhen Rtotal is large (i.e., a complete sheath), then Rtotal>>Zc, and the phase shift θ between the bipolar node 320 and the sheath node 330 is zequ When Rtotal is small (ie, the sheath is broken), the phase shift θzequu is large, and the phase shift between the nodes 320 and 330 is large.

[0039] A monitoring and detection circuit coupled to detect a change in the characteristics of an HF signal coupled to the shield through a parasitic coupling capacitance

[0040] Figure 4A-4B is a schematic block diagram representing an example monitoring and detection system 402 coupled to a bipolar lead 122 - 1 (or 122 - 2 ) to monitor characteristics of an HF signal parasitically coupled to a shield conductor 212 to detect a discharge current between an activated monopolar end effector 118 and a bipolar end effector 108 . Figure 4A The electrical characteristics of the current path between the shield conductor 212 and the monopolar instrument return pad 128 are shown when the insulating jacket 122S is intact. Figure 4B 1 shows the electrical characteristics of the current path between the shield conductor 212 and the monopolar instrument return pad 128 when the insulating sheath 122S is broken. The current path is displaced from the bipolar end effector 108. More specifically, the current path includes a portion of the shield 212 that is normally electrically isolated from the patient tissue 130 by the insulating sheath 122S. As described below, Figure 4A The intact insulating sheath 122S shown in FIG. 1 prevents parasitic capacitive coupling of current from the conductive shield 212 to the patient tissue 130. However, Figure 4B The ruptured insulating sheath 122S shown in FIG. 1 allows parasitic capacitive coupling of current from the conductive shield 212 to the patient tissue 130. The monitoring and detection circuit 402 detects the discharge of potentially hazardous electrical energy to the patient tissue 130 during electrical contact between the activated monopolar end effector 118 and the bipolar end effector 108. More specifically, the following reference Figure 5 The first example monitoring and detection circuit 402 described detects a change in the current phase at the shield 212 caused by a rupture of the sheath 122S, which forms a series impedance divider, where the parasitic coupling capacitance 216 and the patient impedance Z P The two impedance elements of the series impedance divider are included. In addition, the following reference Figure 8The second example monitoring and detection circuit 402 described detects the changing difference in the voltage magnitude between the shield 212 and the bipolar electrical lead 122-1. When the sheath is intact, Rsh exists, and the voltage difference between 122-1 and 212 is small. When the sheath is broken and the shield comes into contact with the patient tissue, only Rp exists, and the voltage difference between 122-1 and 212 is greater than the case of an intact sheath. A threshold is set in the middle of these two differences. If the voltage difference is greater than the set threshold, the monopolar energy is deactivated.

[0041] refer to Figure 4A-4B , parasitic coupling capacitance (C parasitic ) 216 is typically in the range of about 120 pF, which is about 3800 ohms (reactive). The insulation sheath resistance (Rsh) is typically in the range of about 1 M ohms to about 1 G ohms (resistive). The patient resistance (R P ) are typically in the range of tens of ohms to thousands of ohms (resistive). Figure 4A For the complete insulating sheath 122S, due to the parasitic capacitance (C parasitic )216 and patient resistance (R P ) in series with the large sheath resistance (Rsh), very small currents can be parasitically coupled to the patient tissue 130. However, Figure 4B In the case of a broken insulating sheath, due to the parasitic capacitance (C parasitic )216 is directly coupled in series to the patient resistor (R P ), so a larger current can be parasitically coupled to the patient tissue 130. Figure 4A-4B , the ESU 106 generates a HF unipolar signal 404 on a circuit that includes the monopolar lead 124 between the ESU 106 and the monopolar end effector 118 and includes a path within the patient tissue 130 between the monopolar end effector 118 and the return conductor pad 128, and then a path on the conductor line 126 between the return conductor pad 128 and the ESU 106. During normal operation, the unipolar signal 404 conducted within the monopolar instrument 104 is isolated from the bipolar instrument 102. However, when the activated monopolar end effector 118 is in electrical contact with the bipolar end effector 108, the unipolar HF signal 404 is coupled to the bipolar line 122-1 (indicated by the first unipolar signal component 404-1) and to the bipolar line 122-2 (indicated by the other first unipolar signal component 404-2). Therefore, the electrical contact between the activated monopolar instrument and the bipolar instrument causes the unipolar signal current to flow on the bipolar lead.

[0042] Still reference Figure 4A-4B, a first coupling capacitor 422 is coupled to the monitoring and detection circuit 402, and a unipolar signal component 404-1 (or 404-2) is coupled to the bipolar lead 122-1 (or 122-2). A second coupling capacitor 424 is coupled to the monitoring circuit 402, and a second high frequency (HF) unipolar shield signal component 410 is coupled to the conductive shield 212 from one of the bipolar leads 122-1, 122-2 through the parasitic coupling capacitor 216. It should be understood that the coupled unipolar signal components 404-1, 404-2 have matched phases and magnitudes. It will also be understood that the second HF unipolar shield component signal 410 includes a parasitic coupled portion of at least one of the unipolar signal components 404-1, 404-2 coupled to the bipolar leads 122-1, 122-2. The monitoring and detection circuit 402 determines whether the characteristics of the second HF monopolar shield signal component 410 coupled to the conductive shield 212 through the parasitic coupling capacitor 216 indicate an abnormal current I due to a rupture in the protective jacket 210. M The abnormal current flow at the breach location causes a change in the characteristics of a portion of the HF shield signal component 410 coupled to the conductive shield 212 from one or both of the bipolar leads 122 - 1 , 122 - 2 through the parasitic coupling capacitor 216 .

[0043] A monitoring and detection circuit configured to detect changes in the phase shift characteristics of an HF signal coupled to a shield through a parasitic coupling capacitance

[0044] Figure 5 is an illustrative schematic diagram showing details of a first example monitoring and detection circuit 402 for detecting an RF signal phase shift change event. The inventors have recognized that in the presence of an abnormal unipolar current I M The impedance of the flowing patient tissue affects the characteristics of the RF signal coupled to the shield 212 through the parasitic coupling capacitance 216 between the first bipolar lead 122-1 and the second bipolar lead 122-2 and the shield 212. In particular, the phase shift is caused by the parasitic coupling capacitance 216 and the impedance Z P The impedance divider formed by the impedance Z P Includes patient tissue impedance and, if the sheath is intact and not ruptured, the insulating sheath impedance.

[0045] Coupling capacitors 422-1, 422-2 couple first HF monopolar signal components 404-1, 404-2 to first example monitoring and detection circuit 402. Coupling capacitor 424 couples second HF monopolar shield signal component 410 to first example monitoring circuit 402. Coupling capacitors 422-1, 422-2 and 424 each comprise a high impedance PCB embedded parallel plate capacitor.

[0046] The first example circuit 402 includes a pre-processing circuit system 501, which includes an input voltage divider circuit block 502, an input amplifier circuit block 504, a first low pass filter block 506, a comparator circuit block 508, a second low pass filter (LPF) block 510, a Schmitt trigger circuit block 512, and a voltage level shift circuit block 514. The output of the pre-processing circuit system 501 is provided to a first example logic circuit block 516, which determines the change in the phase shift characteristic of the second HF unipolar signal component 410 coupled to the conductive shield 212 relative to the first HF unipolar signal component 404-1, 404-2 coupled to the bipolar leads 122-1, 122-2. In the first example monitoring and detection circuit 402, the first example logic circuit 516 includes a field programmable gate array (FPGA). The processor circuit 518 generates a control signal based on the phase shift characteristic determined by the monitoring and detection circuit 402.

[0047] In the first example monitoring and detection circuit 402, the detected characteristic is the phase relationship between the HF unipolar signal component 404-1, 404-2 on one of the bipolar leads 122-1, 122-2 and the HF unipolar signal component 410 coupled to the conductive shield 212. During activation of the monopolar ESI 104, if the monopolar electrode 118 is in contact with either of the bipolar jaws 110, 114, the first example monitoring and detection circuit 402 measures the phase difference between the HF unipolar signal component 404-1, 404-2 on the bipolar leads 122-1, 122-2 and the HF unipolar signal component 410 capacitively coupled to the bipolar shield 212. If there is no breach in the sheath, the phase difference between the signal components is negligible. However, if the breach 210 occurs in the protective sheath 122S and the protective shield 212 is in contact with the patient tissue 130, the abnormal unipolar current I across the parasitic coupling capacitance 216 is M The flow causes a considerable phase shift between the HF unipolar signal present on the bipolar leads 122-1, 122-2 and the HF unipolar signal present on the shield 212. The first example monitoring and detection circuit 402 measures the phase shift difference. The magnitude and duration of the phase shift are used to determine the occurrence of a rupture. For example, a phase shift difference greater than a specified threshold indicates a tear in the insulating sheath. In the first example monitoring and detection circuit 402, the processor 518 generates a control signal based on the magnitude and duration of the measured phase shift determined. For example, the control signal causes one or more of the following: terminating the unipolar energy delivery to prevent patient delivery, sending a message to a user (e.g., a surgeon), or saving the data to a memory device for later analysis.

[0048] The first example monitoring and detection circuit 402 includes an input signal pulse detection channel for each received HF unipolar signal component. The first pulse detection circuit channel pre-processes the HF unipolar signal component 404-1 on the bipolar lead 122-1 for input to the first example logic circuit 516. The second pulse detection circuit channel pre-processes the HF unipolar signal component 404-2 on the bipolar return lead 122-2 for input to the first example logic circuit 516. The third pulse detection circuit channel pre-processes the HF unipolar signal component 410 coupled to the conductive shield 212 for input to the first example logic circuit 516.

[0049] Referring to the first pulse detection circuit channel, the first coupling capacitor 422-1 couples the HF unipolar signal component 404-1 from the active bipolar lead 122-1 to the input voltage divider block 502, wherein the first voltage divider circuit 502-1 including resistors R1, R2 coupled as shown divides the voltage level of the HF unipolar signal component 404-1 received on the first channel into voltage levels suitable for input to the voltage amplification block 504, which includes the first amplifier circuit 504-1 to amplify the voltage level of the received first channel RF signal. The first low pass filter 506-1 within the first low pass filter block 506 low pass filters the amplified first channel HF signal. The first comparator circuit 502-1 within the comparator block 508 compares the low pass filtered first channel HF signal with the bipolar lead threshold detection signal to convert the first channel HF signal into a square wave signal. The first digital to analog converter (DAC) circuit 542 converts the first digital signal value 552 provided on line 541 to generate a first (bipolar lead) threshold detection signal. A typical received first channel RF signal has a sinusoidal waveform, and each pulse consists of half of the sinusoidal signal period. The first comparator circuit 508-1 converts the received first channel RF signal waveform into a square waveform based on comparison of the rising and falling edges of the sinusoidal signal with the shield threshold detection signal.

[0050] The first low pass filter 510-1 within the second LPF block 510 low pass filters the first channel signal that has been converted to a square wave waveform. It should be understood that the first LPF 506 filters the original input signal and the second LPF 510 filters the noise of the digital signal output from the comparator 508. The first Schmitt trigger circuit 512-1 within the Schmitt trigger block 512 acts as a noise filter to remove noise from the filtered first channel square wave signal. The first level shift circuit 514-2 within the level shift block 514 shifts the voltage level of the smoothed first channel HF square wave signal to a voltage level suitable for input to the first example logic circuit 516. Therefore, it should be understood that the comparator and the Schmitt trigger cooperate to convert the first HF unipolar signal component 404-1 into a substantially noise-free square wave signal.

[0051] The second and third pulse detection circuit channels of the first example monitoring and detection circuit 402 preprocess the corresponding HF unipolar signal components 404-2 on the bipolar lead 122-2 and the HF unipolar signal component 410 on the shield 212 for input to the first example logic circuit 516. The preprocessing of the HF unipolar signal components 404-2, 410 is similar to the preprocessing of the HF unipolar signal component 404-1, except that the third comparator 508-3 compares the HF unipolar shield component signal 410 with the second active / return threshold signal generated by the second DAC 544, which converts the second digital signal value 554 provided on the line 543 to generate the second (shield) threshold detection signal. By referring to the accompanying drawings and the above description of the first channel preprocessing, those of ordinary skill in the art will readily understand the operation of the circuit components in the second and third channels and the preprocessing of the second and third channel RF signals on the second and third channels. Therefore, for the sake of brevity, the second and third channel preprocessing will not be described in detail herein.

[0052] Figure 6 is a schematic flow chart showing a monitoring process 600 for monitoring the phase relationship between the HF monopolar signal components 404-1, 404-2 and the HF monopolar shield signal component 410 to detect an abnormal monopolar current I in the patient tissue 130 indicating a breached insulating sheath 122S M The first example logic circuit 516 is configured to execute Figure 6The first monitoring process of the present invention. The user provides an input command to the first input logic module 602 to select an algorithm from a storage memory device 604 to configure the logic circuit 516. The storage memory device 604 stores a plurality of different selectable program instructions to configure the logic device 516 to implement a plurality of different selectable algorithms (described below) to detect the occurrence of abnormal current. The user provides an input command to the second input logic module 606 to input the parameters of the selected algorithm. Example input parameters include the length of the sampling window and the phase threshold. The user provides an input command to the third input logic module 608 to configure the logic circuit 516 to select the comparator threshold. More specifically, the user provides an input command to cause the first digital signal 552 to be provided to the first DAC 542, thereby setting the shield signal threshold detection level of the first comparator 508-1 and the second comparator 508-2. The user provides an input command to cause the second logic signal 554 to be provided to the second DAC 544 to set the threshold detection signal of the third comparator 508-3. The comparator threshold signal is set to cause the comparator to generate a digital output in response to the sinusoidal input signal crossing the selected threshold. Different comparator threshold settings can be used for the HF unipolar signal components 404-1, 404-2 on the one hand and the HF unipolar shield signal component 410 on the other hand, because there may be differences in voltage amplitude introduced due to parasitic coupling capacitance. The fourth phase difference sampling logic module 610 monitors the phase relationship between the HF signals 404-1, 404-2 coupled from the bipolar leads 122-1, 122-2 and the HF unipolar signal component 410 coupled from the shield 212. The fifth phase-shifted abnormal current detection logic 612 configures the first example logic circuit 516 to evaluate the phase relationship between the coupled unipolar signal components 404-1, 404-2 and the coupled HF shield signal component 410 based on the selected algorithm and the selected comparator threshold, thereby determining whether an abnormal unipolar current 1M caused by contact between two ESIs associated with a rupture in the insulating sheath has occurred within the patient anatomical structure 130. The control loop including the fourth logic module 610 and the fifth logic module 612 continues to operate when the bipolar instrument 102 and the monopolar instrument 104 are active unless the fifth module 612 detects an abnormal current. The sixth warning logic module 614 configures the first example logic circuit 516 to send a control signal to the processor 518 in response to detecting the abnormal current. As described above, in response to receiving a signal indicating the presence of an abnormal current, the processor 518 provides one or more control signals to alert the processor 518, for example, resulting in one or more of the following: terminating monopolar energy delivery to prevent patient delivery, sending a message to a user (e.g., a surgeon), or saving data to a storage device for later analysis.

[0053] Figure 7 It is shown in Figure 6 Schematic signal diagram of example signals generated by the first example monitoring circuit during the process of . The RF bipolar square wave signal and the HF shield square wave signal generated by the first, second and third pulse detection circuit channels are received as inputs at the logic circuit 516 . Figure 7 HF bipolar square wave signal 702 shown in the figure represents a pre-processed version of one of the HF unipolar signal components 404-1, 404-2 coupled from the bipolar leads 122-1, 122-2 that has been conditioned by one of the first and second pulse detection circuit channels of the pre-processing circuit 501. HF shield square wave signal 704 represents a version of the HF unipolar shield signal component 410 coupled from the shield 212 that has been conditioned by the third pulse detection circuit channel of the pre-processing circuit 501. Pulse sampling window signal 706 is generated by the internal logic of logic circuit 516 and represents a sequence of sampling time intervals, wherein logic circuit 516 determines a sequence of phase relationships between pulses of the HF square wave signal 702 and pulses of the HF shield square wave signal 704. During successive sampling windows, logic circuit 516 generates a good phase event sampling pulse signal 708 in response to determining that the HF bipolar lead and HF shield square wave signals have substantially matched phases, and logic circuit 516 generates a bad phase event sampling pulse signal 710 in response to determining that the RF bipolar and RF shield square wave signals have mismatched phases.

[0054] refer to Figure 6-Figure 7 , Figure 6The fourth phase difference sampling logic module 610 shown in Figure 5 configures the logic circuit 516 to identify the occurrence time of the center of the consecutive pulses of the HF bipolar square wave 702 by identifying the occurrence time of their corresponding rising edges and falling edges. Similarly, the fourth phase difference sampling logic module 610 configures the logic circuit 516 to identify the occurrence time of the center of the consecutive pulses of the HF shield square wave 704 by identifying the occurrence time of their corresponding rising edges and falling edges. The fourth phase difference sampling logic module 610 configures the logic circuit 516 to evaluate the phase relationship of the HF unipolar signal components 404-1, 404-2 on the bipolar leads 122-1, 122-2 and the HF unipolar shield signal component on the shield 212 during the consecutive sampling time windows based on the measurement of the difference in the occurrence time of the square wave pulses corresponding to the unipolar signal components on the bipolar leads 122-1, 122-2 and the square wave pulses corresponding to the unipolar signal components on the shield 212 during the consecutive sampling time windows. For example, during each time window, the logic circuit 516 determines the difference in the time of occurrence of the center of the pulse corresponding to the unipolar signal components 404-1, 404-2 on the bipolar leads 122-1, 122-2 and the time of occurrence of the center of the pulse corresponding to the unipolar shield signal component 410 on the shield 212 during the time window. The fourth phase difference sampling logic module 610 configures the logic circuit 516 to generate a good phase event signal pulse 708 for each sampling time interval in which the time difference between the centers of the pulses is less than the threshold time difference, indicating that an abnormal current event has not occurred. The fourth phase difference sampling logic module 610 configures the logic circuit 516 to generate a bad phase event signal pulse 710 for each sampling time interval in which the time difference between the centers of the pulses is greater than or equal to the threshold time difference, indicating that an abnormal current event may have occurred. It should be noted that since the width of the square wave pulse depends on the amplitude of the sine wave input, which varies with the signal amplitude, the center point of the pulse is used for phase shift determination.

[0055] More specifically, for example, Figure 7The schematic signal diagram of includes five sampling windows: (A)-(E). The example fourth phase difference sampling logic module 610 configures the logic circuit 516 to open the pulse sampling time window when the leading edge of either the HF bipolar square wave pulse 702 and the HF shield square wave pulse 704 appears. During the first example sampling window (A), the HF bipolar square wave pulse 702 and the HF shield square wave pulse 704 both appear within the threshold time difference, thereby generating a good phase event signal pulse 708. Similarly, during the second example sampling window (B), the HF bipolar square wave pulse 702 and the HF shield square wave pulse 704 both appear within the threshold time difference, thereby generating a good phase event signal pulse 708. In the illustrative example signal diagram, the second sampling window (B) is closed in advance after the falling edge of both pulse 702 and pulse 704 appears. As shown in the third example sampling window (C), if a sampling window is opened when a pulse 702 or a pulse 704 is received (e.g., a high level), the time when the sampling window is opened is considered to be the leading edge of the pulse. During the third example sampling window (C), pulse 702 and pulse 704 are separated in time by an amount greater than the threshold time difference, thus generating a bad phase event signal pulse 710. The example fourth phase difference sampling logic module 610 is configured to handle situations where, for example, multiple pulses 702 or multiple pulses 704 occur during a sampling window, as shown in the fourth example sampling window (D). The example sampling logic module 610 can be configured to make a good / bad determination based on, for example, the first pulse, the last pulse, or the largest pulse, or based on the midpoint of the first rising edge and the last falling edge. For the fourth example sampling window (D), it is determined that both pulse 702 and pulse 704 occur within the phase difference threshold, thus generating a good phase event sampling pulse signal 708. The example sampling logic module 610 can be configured such that when only one of the two pulses 702, 704 occurs during the sampling window, neither a good pulse nor a bad pulse is generated. For example, during the fifth example sampling window (E), there is an occurrence of pulse 702, but there is no occurrence of pulse 704, thus no good / bad pulse is generated.

[0056] Figure 6 The fifth abnormal current detection logic 612 configures the logic circuit 516 to use the selected phase difference based algorithm configured according to the selected algorithm parameters to detect abnormal current based on an evaluation of the HF phase difference between the unipolar signal component on the bipolar lead and the unipolar signal component on the shield, as indicated by a series of good pulses and / or bad pulses.

[0057] Algorithm for detecting abnormal current based on comparison of the component of the HF signal conducted on the lead with the component of the HF signal conducted on the shield

[0058] A first exemplary selectable phase difference based algorithm configures the logic circuit 516 to detect the presence of abnormal current in response to a continuous sequence of bad phase event sampling pulses of at least a specified duration. Selectable parameters of the first exemplary phase difference based algorithm include a phase difference threshold and a specified duration. Example durations are typically in the range of one-half to three-quarters of an ESU cycle.

[0059] A second exemplary selectable phase difference based algorithm configures the logic circuit 516 to detect the presence of abnormal current in response to at least a specified number (pulse count) of bad phase event sampling pulses during a specified duration. Selectable parameters for the second exemplary phase difference based algorithm include a typical phase difference threshold of 30-60 degrees of phase shift and a specified bad phase event pulse count and a specified duration. Example durations are typically in the range of five hundred microseconds to two milliseconds.

[0060] A third exemplary selectable phase difference based algorithm configures the logic circuit 516 to detect the presence of abnormal current in response to at least a specified number (count) of consecutive bad phase event sampling pulses. Selectable parameters of the third exemplary phase difference based algorithm include a phase difference threshold and a predetermined consecutive count of bad phase event sampling pulses. An example number of consecutive bad phase event sampling pulses is generally in the range of three to seven.

[0061] A fourth exemplary selectable phase difference based algorithm configures the logic circuit 516 to detect the presence of abnormal current in response to at least a specified number (count) of consecutive bad phase event sampling pulses within a specified duration. Selectable parameters of the fourth exemplary phase difference based algorithm include a phase difference threshold, a specified number of bad phase event pulses, and a specified duration.

[0062] A fifth exemplary selectable phase difference based algorithm configures the logic circuit 516 to detect the presence of abnormal current in response to observing a specified ratio of bad phase event sampling pulses to good phase event sampling pulses within a specified duration. Selectable parameters for the fifth exemplary phase difference based algorithm include a phase difference threshold and a specified number ratio and a specified duration.

[0063] The ESU 106 generates different modes of bipolar lead signals for different surgical procedures. For example, the ESU 106 generates a cutting mode signal to cut tissue. The cutting mode signal typically includes a continuous (non-pulsed) output. The ESU 106 generates a coagulation mode signal to coagulate tissue. The coagulation mode signal is typically pulsed with a very low duty cycle. The ESU 106 generates a mixed mode signal to mix tissue. The duty cycle of the mixed mode signal is typically between continuous and a low duty cycle for coagulation.

[0064] The algorithm type may be selected using the first input module 602 based on the unipolar output setting and the ESU mode. For example, the algorithm type may be selected based on the power or effect setting and mode (which means duty cycle). Similarly, the parameters may be selected using the second input module 604 based on the unipolar output setting and the ESU mode such as the power or effect setting and mode (which means duty cycle). The comparator threshold may be selected using the third input module based on the unipolar output setting and the ESU mode. For example, the comparator threshold may be selected based on the expected amplitude of the HF output signal.

[0065] Monitoring and detection circuitry configured to detect changes in magnitude characteristics of an RF signal coupled to a shield through parasitic coupling capacitance

[0066] Figure 8 is an illustrative schematic diagram showing details of a second example monitoring and detection circuit 402-2 for detecting an RF signal magnitude change event. As described above, the inventors have recognized that in the presence of an abnormal unipolar current I M The impedance Z of the patient's tissue during the flow p The characteristics of the HF unipolar signal component coupled to the shield through the parasitic coupling capacitance 216 between the first bipolar lead 122-1 and the second bipolar lead 122-2 and the shield 212 are affected. In particular, during abnormal unipolar current flow, the magnitude of the unipolar signal component on the shield varies with the series impedance divider Z p The series impedance divider Z p Including the sheath resistance (R sh ) in series with the patient's tissue resistance (R p ). Refer to the equation, for example, as Z p Approaching infinity, the unipolar shield voltage approaches the unipolar voltage on the bipolar lead. Therefore, if the shield is intact, Z p is actually infinite, no current flows through the patient tissue 130, and the magnitude of the unipolar signal shield voltage matches the magnitude of the unipolar signal bipolar lead voltage. However, if the shield is breached, then Z PWith a lower voltage magnitude, a certain unipolar signal component current flows through the patient tissue 130, and the magnitude of the unipolar signal shield voltage is less than the magnitude of the voltage of the unipolar signal component on the bipolar lead. The second monitoring and detection circuit 402-2 is configured to compare the magnitude of at least one of the HF unipolar signal components 404-1, 404-2 with the magnitude of the HF unipolar shield signal component 410 to determine whether a potentially harmful unipolar current flows through the patient tissue. If the magnitudes match, it is determined that no hazardous current exists. If the magnitudes differ by a certain specified magnitude, it is determined that a hazardous current exists. The second example monitoring and detection circuit 402 includes a pre-processing circuit system 801, which includes an input voltage divider circuit block 802, an input amplifier circuit block 804, and an analog-to-digital converter circuit block 806, which detects signal pulses. The output of the pre-processing circuit system 801 is provided to the logic circuit 516, which determines the change in the signal magnitude characteristic of the HF monopolar shield signal component 410 relative to the HF monopolar signal components 404-1, 404-2. In the second example monitoring circuit, the logic circuit 516 includes an FPGA. The processor circuit 518 generates a control signal based on the change in the RF shield signal magnitude characteristic determined by the second example monitoring and detection circuit 402.

[0067] More specifically, the second example monitoring circuit 402 includes a first channel for preprocessing one of the HF monopolar signal components 404-1, 404-2, and includes a second channel for preprocessing the HF monopolar shield signal component 410. In most cases, the voltage magnitude is the same on both bipolar leads, and therefore it is not necessary to measure the voltage on both leads.

[0068] Referring to the first channel, the first coupling capacitor 422 couples the HF unipolar signal component 404-1 (or 404-2) to the input voltage divider block, wherein the first voltage divider circuit 802-1 including resistors R1, R2 coupled as shown divides the voltage level of the HF unipolar signal component received on the first channel into a voltage level suitable for input to the voltage amplification block 804, which includes a first amplifier circuit (not shown) to amplify the voltage level of the received HF unipolar signal component. A first analog-to-digital converter (ADC) converts the amplified HF unipolar signal component and provides an amplified RF bipolar lead signal as an input to the logic circuit 516.

[0069] The second channel of the preprocessing circuit 801 preprocesses the HF monopole shield signal component 410. The preprocessing of the HF monopole shield signal component 410 coupled from the second coupling capacitor 424 is similar to the preprocessing of the HF monopole signal component 404-1. By referring to the accompanying drawings and the above description of the first channel preprocessing, those of ordinary skill in the art will readily understand the operation of the circuit components in the second channel. Therefore, for the sake of brevity, the second channel preprocessing will not be described in detail herein.

[0070] The monitoring process performed using the second example monitoring and detection circuit 402-2 is similar to that described above with reference to Figure 6 The monitoring process described, but the comparator block 608 is not selected. In addition, in the second monitoring and detection circuit 402-2, the logic circuit 516 compares the voltage magnitude of the first unipolar signal component 404-1, 404-2 on at least one of the bipolar leads 122-1 or 122-2 with the voltage magnitude 410 of the second unipolar signal component on the shield 212 to detect potentially dangerous abnormal unipolar currents. In addition, the logic circuit 516 of the second monitoring and detection circuit 402-2 can be configured to execute the first to sixth example algorithms modified to compare signal component magnitude differences instead of signal component phase differences. More specifically, the example logic circuit 516 determines whether the magnitude of the difference between the voltage magnitude of the first unipolar signal component 404-1, 404-2 on at least one of the bipolar leads 122-1 or 122-2 and the voltage magnitude 410 of the second unipolar signal component on the shield 212 exceeds a threshold magnitude difference. The logic circuit 516 of the example circuit 402-2 generates a good magnitude event sampling pulse signal (not shown) in response to determining that the HF bipolar lead and HF shield signals have substantially matched magnitudes; that is, the magnitude difference does not exceed the magnitude difference threshold. The logic circuit 516 of the example circuit 402-2 generates a bad magnitude event sampling pulse signal (not shown) in response to determining that the HF bipolar lead and HF shield signals have mismatched magnitudes; that is, the magnitude difference exceeds the magnitude difference threshold.

[0071] The above description is presented to enable any person skilled in the art to create and use a system and method for detecting a rupture in an insulating sheath of a bipolar electrosurgical instrument. Various modifications to the embodiments will be clear to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the scope of the invention. In the foregoing description, many details are presented for explanation. However, one of ordinary skill in the art will recognize that the circuit may be practiced without using these specific details. In other examples, well-known circuits and processes are shown in block diagram form so as not to obscure the description of the invention with unnecessary details. In different drawings and specifications, the same figure numerals may be used to represent different views of the same or similar items. Therefore, the above description and drawings according to the examples of the present invention are merely illustrative of the principles of the present invention. Therefore, it should be understood that one skilled in the art may make various modifications to the examples without departing from the scope of the invention defined in the appended claims.

Claims

1. A system for detecting a rupture of an insulating sheath in a bipolar electrosurgical instrument, the bipolar electrosurgical instrument comprising: End effector; conductive leads for electrically coupling the end effector to an electrosurgical generator unit; and a conductive shield surrounding the leads; wherein the insulating sheath surrounds the conductive shield, the system comprising: a first pulse detection circuit for detecting a first HF signal component of a high frequency signal, ie, an HF signal, conducted on the lead; a second pulse detection circuit for detecting a second HF signal component of the HF signal conducted on the shield; phase difference sampling logic for generating a series of sampled values ​​indicative of a phase difference between the first HF signal component and the second HF signal component over a time interval; Current detection logic is used to detect current between the shield and anatomical tissue based on the series of sampled values.

2. The system according to claim 1, wherein the first pulse detection circuit comprises a first comparator circuit for comparing the first HF signal component with a first threshold value; and The second pulse detection circuit comprises a second comparator circuit, which is used to compare the second HF signal component with a second threshold value.

3. The system according to claim 2, Wherein the first threshold matches the second threshold.

4. The system according to claim 2, further comprising: A first threshold level setting circuit, which is used to set the first threshold; as well as The second threshold setting circuit is used to set the second threshold.

5. The system according to claim 2, wherein the first pulse detection circuit further comprises at least one first low-pass filter; and The second pulse detection circuit further includes at least one second low-pass filter.

6. The system according to claim 2, wherein the first pulse detection circuit further comprises at least one first noise filter; and The second pulse detection circuit further includes at least one second noise filter.

7. The system of claim 1, further comprising: a first coupling capacitor for coupling the first HF signal component to the first pulse detection circuit; as well as A second coupling capacitor is used to couple the second HF signal component to the second pulse detection circuit.

8. The system according to claim 1, The current detection logic detects current based on a count of high phase angle event samples.

9. The system according to claim 1, The current detection logic detects current based on a comparison of a count of high phase angle event sampling pulses with a count of low phase angle event sampling pulses.

10. The system according to claim 1, The current detection logic detects current in response to a continuous sequence of high phase angle event samples within a predetermined duration.

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