Tissue treatment device

Abstract

To provide an electrosurgical device that provides support to a treating person during positioning of an instrument in a tissue to be treated.SOLUTION: An instrument 14 is suitable for treatment of lung tumors and other tissues and a respective apparatus 15 detects the correct positioning of the instrument and its two electrodes in a suitable target tissue 11 by observation of two parameters and particularly their time-dependent change. If the change of the two parameters exceeds defined thresholds respectively, a contact between the instrument and the tissue to be treated and thus also the positioning of the instrument in a desired position can be derived from the change.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electrosurgical device for electrothermal treatment of living tissue, and further to a method for positioning an instrument that is part of the device within living tissue. [Background technology]

[0002] It is generally known to detect and monitor contact between a treatment electrode and biological tissue by electrical measurements. For this purpose, U.S. Patent Nos. 5,999,929 and 5,999,929 disclose an ablation system and a method for real-time feedback of lesion formation. The degree of electrical coupling between the ablation electrode and the biological tissue is determined. Based on this, the volume of the created lesion can be estimated. To determine the degree of contact, the phase ratio between the applied voltage and the resulting current can be used. For this purpose, a phase measurement circuit is provided.

[0003] Also, Patent Document 3 proposes detecting the phase position of the voltage and current at the treatment electrode of the instrument, utilizing the recognition that the phase relationships before, during, and after contact are characteristically different from one another.

[0004] Patent Document 4 discloses determining the type of tissue in contact with an instrument. For this purpose, alternating voltages with various frequencies are supplied to the instrument and introduced into the tissue, and the resulting current is monitored. This method is also called impedance spectroscopy.

[0005] During the specific coagulation of tissue volumes in a living human or animal patient, it is often important to position the respective instrument, in particular its electrodes, within the tissue to be treated, in particular the tissue to be coagulated, in order to obtain a good treatment result. Therefore, the surgeon's view of the tissue to be treated is usually limited. This is especially true when the tissue to be treated is not exposed but is surrounded or buried by other tissues that must be carefully treated during the procedure. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2009 / 065140 [Patent Document 2] U.S. Patent Application Publication No. 2017 / 0312009 [Patent Document 3] European Patent Application Publication No. 2612612 [Patent Document 4] German Patent Application Publication No. 102019209333 Summary of the Invention [Problem to be solved by the invention]

[0007] This leads to the object of the present invention to provide an electrosurgical device that assists the practitioner during positioning of the instrument within the tissue to be treated.It is a further object of the present invention to provide a respective method. [Means for solving the problem]

[0008] These objects are achieved with an electrosurgical device according to claim 1 and a method for locating a tumor in healthy tissue according to claim 15.

[0009] An instrument, preferably having an elongated needle- or pin-like basic shape, capable of penetrating biological tissue is part of the electrosurgical device according to the invention. The instrument preferably comprises two or more electrodes arranged in the instrument at an axial distance from each other. For example, the instrument is a hose-like instrument that can be inserted into the body, for example through an endoscope, and has a distal end portion on which the electrodes, realized as coil electrodes, cylindrical electrodes, etc., are arranged. The instrument can be cooled from the inside to prevent or limit heating of the electrodes. The electrodes, preferably arranged at an axial distance from each other, preferably serve as treatment electrodes, and for this purpose, a treatment voltage U HF For this purpose, the electrodes are supplied with such a treatment voltage UHF connected to an electrosurgical generator that outputs the treatment voltage U HF is a high frequency alternating voltage, usually having a frequency higher than 100 kHz. Furthermore, the generator generates a treatment voltage U HF (e.g., 10-20 times) lower than the test voltage U and therefore have no or only a slight physiological effect. T is output to the same electrode. Test voltage U T serves to confirm and display the positioning of the instrument in the biological tissue, for example in the target tissue, such as a tumor, which, after accurate positioning of the instrument, is subjected to a treatment voltage U HF and is then thermally destroyed thereby.

[0010] The present invention takes advantage of the fact that tumor tissue has a very good blood supply and is therefore electrically differentiated from adjacent healthy tissue. This property of tumors allows the device to be reliably positioned within the tumor tissue, avoiding misplacement.

[0011] The generator generates a test voltage U between the two electrodes of the instrument. T The control device detects the current i generated by the test voltage U T and the current i, two characteristic parameters are determined. One of the two parameters depends on the impedance available between the electrodes. The other of the two parameters depends on the phase angle between the test voltage and the current. For example, the first parameter can be an impedance quantity, and the second parameter is a power factor or another parameter that depends on the phase angle phi between the current and the voltage. The power factor is the quotient of the converted real power available between the electrodes in the tissue to the apparent power.

[0012] The control device monitors changes in the two parameters during insertion of the instrument into the biological tissue and determines whether each of the two changes exceeds a predetermined threshold. The changes in the two parameters can be understood as changes over time, and each change in the parameter is measured as the difference between the parameter occurring between two subsequent points in time within a defined time interval.

[0013] The controller can be configured in a variety of ways.

[0014] In a first variant, the control device can output a signal whenever the change in the two parameters exceeds their two thresholds.

[0015] In another variation, the control device can output a first signal if the change exceeds those two thresholds in a first direction, and subsequently output a second signal if the direction of the change changes.

[0016] In another variation, the control device can set two parameters as reference parameters if both changes exceed a predetermined threshold. The definition of the two reference parameters can be associated with the output of a first signal as an option to indicate to the surgeon that the target tissue has been reached. Furthermore, the control device can output a second signal if the difference between the two parameters and the reference parameter exceeds a predetermined amount. Alternatively, the control device can output a second signal if the direction of change in the reference parameter changes after setting the reference parameter. The first and second signals can be equal or different. Furthermore, a signal can be generated as long as the two parameters do not deviate from the two reference parameters (within a specified or definable tolerance range).

[0017] The output signal may be, for example, an acoustic signal, an optical signal or a combination of both, and the optical signal may be visually displayed on a display of an electrosurgical system that includes the electrosurgical generator.

[0018] According to the concept of the present invention, the operator inserts the instrument into the tissue at a normal speed. A normal insertion speed is approximately 0.5 cm / s. For example, in the case of treating a lung tumor, an impedance Imp greater than 300 ohms and a power factor LF = cos(phi) < 0.75 result in healthy lung tissue. As soon as one of the electrodes, particularly the distal electrode of the instrument, comes into contact with tumor tissue, both parameters, i.e., impedance and power factor, change. Now, as the instrument is further inserted into the target tissue and the distal end of the proximal electrode comes into contact with the target tissue, for a normal insertion speed and a normal instrument size, the impedance drops by approximately at least 60% relative to the previously measured impedance within a certain period of time, e.g., within 2 seconds, while the power factor increases by approximately 20% relative to the previous power factor for a specified period of time (e.g., 2 seconds). This applies particularly to a normal instrument with an axial electrode length of 8 mm to 9 mm and an axial electrode distance of 3 mm to 4 mm. The changes in the two parameters are detected by the control device. The controller can output a signal accordingly, from which the practitioner can conclude that both electrodes are in contact with the tumor tissue. According to an alternative embodiment of the controller described above, instead of or in addition to a direct signal output, the controller can store the value of the parameter as a reference parameter when the parameter changes relative to the stored reference parameter. For example, the position of the tool's electrodes within the target tissue can be shown to the user on a display provided on the device 15.

[0019] During the measurement of two parameters, for example, impedance and power factor, several subsequent values ​​are measured, from which moving average For example, the first parameter is preferably determined as moving average while the second parameter can be the power factor moving average The device according to the present invention can measure the time at different times. moving averagecan be compared and set with each other, and these points in time are related to each other by a defined time interval. The practitioner can then make adjustments to the individual insertion speed. If the practitioner inserts the electrode fairly slowly, they should select a larger time interval, and if they tend to insert the device fairly quickly, they should tend to select a shorter time interval.

[0020] Furthermore, the insertion process can be automated by providing a drive that moves the instrument distally, e.g., at a constant speed and / or in a displacement-controlled manner. This allows the drive to generate position data characterizing the respective position of the instrument relative to its longitudinal direction. Changes can be determined over time or as position-dependent changes. The latter is also possible during manual insertion of the instrument if the instrument is connected to a suitable displacement measuring device. Such a displacement measuring device can provide data indicating, for example, how far the instrument has moved in the distal axial direction. In the simplest case, such a displacement measuring device can be provided in an endoscope or bronchoscope, e.g., with a measuring wheel at its proximal end that contacts and rotates with the instrument body (of the probe) as the probe advances axially.

[0021] Further advantageous details of the invention are the subject matter of the dependent claims and the description and the assigned drawings. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic view of the device according to the invention during treatment of living tissue. [Figure 2] FIG. 2 is a diagram of an instrument that is part of the device according to FIG. 1 during penetration into the tissue that needs to be treated. [Figure 3] FIG. 3 is a schematic partial longitudinal cutaway view of the device according to FIG. [Figure 4] FIG. 4 is a diagram of the voltage and current of the instrument during insertion and treatment. [Figure 5]FIG. 5 shows the time course of different parameters determined from the voltage and current. DETAILED DESCRIPTION OF THE INVENTION

[0023] 1 shows a device 10 useful for treating biological tissue 11, such as lung tissue, which may comprise, for example, healthy lung tissue 12 and an embedded tumor 13. The device 10 comprises at least an instrument 14 and an apparatus 15 for supplying the necessary operating media, such as a cooling medium and electrical current, to the instrument 14. The instrument 14 may be a flexible probe 16 that can be guided to the target tissue 11, for example, through a bronchoscope 17.

[0024] During treatment of other tissues, other instruments may be used, such as endoscopic, laparoscopic or even open surgical instruments.The present invention is not limited to bronchoscopes.

[0025] The device 14 is further shown in Figures 2 and 3. The device 14 comprises an elongated body 18, configured for example as a hose, on which a distal electrode 19 and a second electrode 20 are arranged at a distance in the proximal direction. The electrodes 19, 20 typically have an axial length of 7 mm to 10 mm and are electrically insulated from each other. For this purpose, the electrodes 19, 20 are arranged at an axial distance of, for example, 3 mm to 5 mm. The electrodes 19, 20 are realized for example as cylindrical sleeves, coils, etc., and have a diameter of, for example, 2 mm to 3 mm.

[0026] The electrodes 19, 20 can be supplied with voltage and current via electrical lines which preferably extend through the probe 16 and are connected to the instrument 15. In FIG. 1, the instrument 15 is connected to a test voltage U T or treatment voltage U HF The device includes an RF generator 23 controlled by a controller 24 to supply a radio frequency (RF) signal to the electrodes 19, 20.

[0027] The instrument 14 may enclose a lumen 25 that is supplied with a cooling medium via a capillary tube 26 disposed within the lumen 25. The cooling medium may serve to cool the electrodes 19, 20 to prevent desiccation of tissue in contact with the electrodes 19, 20 during the procedure.

[0028] As shown in FIG. 1 , the bronchoscope 17 can optionally be provided with a displacement measuring device 27, which can determine the current position of the probe 16 during insertion into the bronchoscope 17 and penetration into the tissue 11. For example, a wheel 28 in frictional contact with the probe 16 and a resolver 29 can be part of the displacement measuring device. Alternatively, displacement markings that can be read by the displacement measuring device 27 can be applied to a coating on the probe 16. Furthermore, it is possible to automatically penetrate the tissue 11 with the probe 16. For this purpose, a motor 30 can be provided that is drivingly coupled to the wheel 28. The resolver 29 or other displacement measuring device 27, and the motor 30, if provided, are then connected to the control device 24.

[0029] The control device 24 may include input means 31 such as a keyboard, touch screen, etc., to affect its operation, which may input predetermined values, such as voltages, currents, powers, thresholds, etc. over a period of time, and transmit them to the control device.

[0030] The generator 23 generates the treatment voltage U HF Or test voltage U T In the figure, the test voltage U T can only have a magnitude of a few volts, for example 10 volts. T is preferably an AC voltage, in particular a high frequency AC voltage having a frequency above 100 kHz. T is sent to the electrodes 19, 20 via lines 21, 22.

[0031] During penetration of the tissue 11, a current i flows between the electrodes 19, 20. The generator 23 determines the magnitude of the current i as well as the test voltage U T The measuring means may, for example, include a test voltage U T and the resulting current i, or a parameter that depends on the phase angle phi (for example, the power factor).

[0032] The generator 23 further generates a treatment voltage U, which may have a magnitude of, for example, 100 volts or a few hundred volts (but preferably <200 Vp). HF Furthermore, this allows the generator 23 to detect the resulting current, although this is not necessary.

[0033] The control device 24 applies a test voltage to the electrodes 19, 20 via the generator 23 during insertion of the instrument 14 into the tissue 11. This causes the control device 24 to further control the voltage U T and the current i, a first parameter G1 is determined which depends on the impedance Imp available between the electrodes 19, 20. This parameter G1 can be, for example, the complex impedance Imp, its real part R=Re{Imp}, its quantity |Imp|, or another parameter derived therefrom, for example the conductance Imp -1 The first parameter G1 can also be expressed by other parameters derived from the impedance Imp.

[0034] Furthermore, the control device 24 may, for example, determine the current i and the test voltage U T A second parameter G2 is determined, which depends on the phase angle phi between the real power P and the apparent power S. The second parameter G2 can be, for example, the power factor LF = cos(phi). The power factor LF can also be obtained from the quotient of the real power P and the apparent power S delivered to the system 11, LF = P / S.

[0035] Furthermore, the control device 24 determines the change V1 in the first parameter G1 and the change V2 in the second parameter G2. By way of example, these changes can be time-varying. For this purpose, the first parameter G1 is moving average can be generated, and the difference between this average between two time points can be determined. The two time points t1 and t2 can be separated by a fixed, defined time interval Δt. The time interval Δt can be, for example, a time interval that can be input by the input device 31. The time interval Δt can be, for example, 0.1 to 5 seconds, and can be adjusted to, for example, 2 seconds. In this case, the first change V1 is the difference between the first parameter G1 at time points t1 and t2, which are separated from each other by approximately the time interval Δt.

[0036] These situations are illustrated in Figure 5. The second change V2 can also be understood as the difference in the second parameter G2 between two different points in time t1, t2. This difference is then preferably determined between the average values ​​of the second parameter G2. For example, the second parameter G2 can be the power factor moving average In this example, the difference is the power factor LF at time t2. moving average and the power factor LF at time t1 moving average is determined from

[0037] The control device 24 determines two changes V1 and V2 during the insertion of the device 14 into the tissue 11. This is shown in Figure 5. First, at the far left of Figure 5, the two electrodes 19, 20 are located in the lung tissue 12. The impedance or its quantity, and therefore the parameter G1, is relatively high, exceeding 300 ohms. The power factor LF is in the range of cosine phi < 0.75.

[0038] At time t0, electrode 19 comes into contact with tumor 13. While instrument 14 continues to penetrate tumor 13, the impedance starts to decrease gradually. At the same time, power factor LF increases gradually. As soon as second electrode 20 is also penetrated into tumor 13 (time t1), impedance Imp starts to decrease faster and power factor LF starts to increase faster. This is evident from the steeper decrease in the curve of G1 and the steeper increase in the curve of G2 in the time window Δt in part A of FIG. 5 (the progression of parameters G1 and G2 in FIG. 5 is shown as moving average It is shown that the diagram is based on the above, i.e., a series of measurements, for example within an elapsed interval of 1 second, are processed and average values ​​are obtained to determine the parameters G1 and G2, respectively.

[0039] of G1 in interval A moving average The amount of difference between the two, i.e., change V1, is greater than 60% and change V2 (i.e., the difference between G2 and G3 in interval A) is greater than 60%. moving average If the difference between V1 and V2 exceeds 20%, the control device 24 can take different actions depending on the configuration. The first option is to immediately output a signal indicating to the operator that both electrodes 19, 20 are sufficiently positioned inside the tumor 13. The tumor treatment is then released. The second option is to output the signal after a fixed or adjustable waiting period. This allows for situations where, in most cases, the changes V1 and V2 already meet the above requirements before the proximal electrode is fully inserted into the tumor. During the waiting period, e.g., 1 second, the user moves the probe somewhat deeper into the tumor. The operator can now switch the generator from test mode to treatment mode, thereby applying the treatment voltage to the electrodes 19, 20. This can be done manually or automatically by a variant of the control device 24.

[0040] In another variant, the control device 24 can also store the parameters G1 and G2 at the end of phase A as reference parameters G1B, G2B, and can output a signal only if both parameters G1, G2 change in opposite directions as shown in part B of Figure 5.

[0041] The device 10 thus far described operates as follows.

[0042] After the instrument 14 is connected to the equipment 15, it is guided through the bronchoscope 17 to the tissue 11 to be treated. The instrument 14 is then moved distally out of the bronchoscope 17 and inserted into the tissue 11. As soon as the electrodes 19, 20 of the instrument 14 are no longer visible to the user, the practitioner applies a test voltage U to the electrodes 19, 20 of the instrument 14. T The generator 23 is activated in test mode to output a test voltage U, which causes the generator 23 to apply to the instrument 14 a low sinusoidal AC voltage, for example less than 10 Vp (Volts Peak), having a frequency of 350 kHz, for example with a power limit of 1 watt. T and the resulting current i have no thermal effect on the tissue 11 because the power is low.

[0043] In test mode, the instrument 14 is further sent into the tissue 11, whereby the impedance Imp and phase angle phi, or parameters G1, G2 derived therefrom, such as the power factor LF, are determined and stored at defined time intervals (e.g., at intervals of 0.1 milliseconds). As long as the instrument 14 is located within the lung tissue 12, the impedance Imp is in the range higher than 300 ohms and the power factor LF is typically less than 0.75.

[0044] As soon as the distal electrode 19 of the instrument 14 comes into contact with the tumor tissue 13, the impedance Imp and power factor LF begin to change characteristically, thereby causing the ablation instrument 14 to penetrate further into the tumor tissue 13.

[0045] If the change V1 in the current value of the impedance Imp relative to the previous impedance Imp a defined time interval (e.g., Δt=2 seconds) exceeds a threshold S1 (e.g., 60%), and at the same time the change V2 in the current power factor LF relative to the power factor LF 2 seconds ago exceeds a threshold S2 (e.g., 20%), then these instantaneous values ​​of the impedance Imp and the power factor LF are defined as onset values. The control device can store the current values ​​G1 and G2 as reference values ​​G1B and G2B.

[0046] Depending on the operator, the time interval Δt may be adjusted to another time interval other than 2 seconds. This change in the time interval Δt can be made using the input device 31.

[0047] The user now moves the instrument 14 further through the tumor 13. The controller 24 then calculates the impedance values. moving average The currently calculated average increase in power factor moving average As soon as the device detects a decrease in V1 and V2 (Fig. 5, part B), it sends a signal to the user indicating that the device is now in contact with the lung tissue again. This means that the device 14 with the electrodes 19, 20 is either asymmetrically positioned inside the tumor 13 or has completely penetrated the tumor 13. The user can recognize this situation, for example, based on a signal displayed on a display unit arranged on the device 15, and retract the ablation device. In this way, the user finds a suitable position for treatment. If the changes V1 and V2 exceed the respective thresholds, a signal can be output in part B. The thresholds may be the same as the thresholds S1 and S2, or may be different from them.

[0048] In a variant, the controller outputs a first signal at part A (FIG. 5) and a second signal at part B to allow the user to find the correct position of the instrument 14 between parts A and B.

[0049] The instruments 14 are suitable for treating lung tumors and other tissues, and each device 15 detects the correct positioning of the instrument 14 and its two electrodes 19, 20 in the appropriate target tissue by observing two parameters G1, G2, particularly their variations over time. If the variations V1, V2 in the two parameters G1, G2 exceed defined thresholds S1, S2, respectively, contact between the instrument and the tissue to be treated, and thus the positioning of the instrument in the desired location, can be deduced from the variations V1, V2. The present invention therefore significantly contributes to improving procedural safety. [Explanation of symbols]

[0050] 10 equipment 11 Biological tissue 12 Healthy lung tissue 13 Tumor 14 Equipment 15 Equipment 16 probes 17 Bronchoscope 18 Base 19 1st electrode 20 2nd electrode 21 and 22 lines 23 Generator 24 Control device 25 lumen 26 Capillary 27 Displacement measuring device 28 wheels 29 Resolver 30 motor 31 Input Method

Claims

1. An electrosurgical device (10) for electrothermal treatment of living tissue (11), comprising: The device includes a body (18) having a first electrode (19) and at least one second electrode (20) arranged at a proximal distance from the first electrode (19), and is capable of being inserted into biological tissue, and a high frequency test voltage (U) is applied to the first electrode (19) and the at least one second electrode (20). Ｔ ) and high frequency treatment voltage (U ＨＦ ) and an instrument (14) capable of supplying The test voltage (U Ｔ an instrument (15) including an electrosurgical generator (23) for supplying a current (i) and detecting the resulting current (i); The test voltage (U Ｔ ) and the current (i), a first parameter (G1) depending on the effective impedance (Imp) between the first electrode (19) and the at least one second electrode (20), and the test voltage (U Ｔ a control device (24) for determining a second parameter (G2) that depends on a phase angle (phi) between the current (i) and the The control device (24) further comprises: a) whether the magnitude of the first change (V1) in the first parameter (G1) exceeds a first threshold (S1); and b) whether the magnitude of the second change (V2) in the second parameter (G2) exceeds a second threshold (S2); Determine Electrosurgical equipment.

2. The first change (V1) and the second change (V2) are changes in the parameters (G1, G2) measured at different times, respectively.

10. The apparatus of claim 1.

3. The control device determines the first change (V1) from the first parameter (G1) determined at different times (t1, t2) defined relative to each other by a time interval (Δt), and the first change (V1) is determined from the difference between the first parameter (G1) determined at the different times (t1, t2).

3. The apparatus of claim 2.

4. The control device determines the parameters (G1, G2) as moving averages.

10. The apparatus of claim 1.

5. The control device (24) is connected to an input means (31) by which the time interval (Δt) can be adjusted.

4. The apparatus of claim 3.

6. The control device defines the values ​​of the first parameter (G1) and the second parameter (G2) as reference parameters (G1B, G2B) when both changes (V1, V2) exceed the defined thresholds (S1, S2) in the respective first directions.

10. The apparatus of claim 1.

7. The control device (24) outputs a signal when the first parameter (G1) and the second parameter (G2) change in a respective second direction opposite to the respective first direction, starting from the reference parameters (G1B, G2B).

7. The apparatus of claim 6.

8. A displacement measuring device (27) is assigned to the instrument, and the control device (24) detects the changes (V1, V2) depending on the displacement, and the control device (24) determines the changes (V1, V2) by the difference between the parameters (G1, G2) determined at different instrument positions.

10. The apparatus of claim 1.

9. The different instrument positions are different positions of the instrument (14) during insertion.

9. The apparatus of claim 8.

10. The first parameter (G1) is the impedance (Imp) and the second parameter (G2) is the power factor (LF).

10. The apparatus of claim 1.

11. The first change (V1) is a decrease in the impedance (Imp) by a predetermined first value.

11. The apparatus of claim 10.

12. The predetermined first value is 60%.

12. The apparatus of claim 11.

13. The second change (V2) is an increase in the power factor (LF) by a predetermined second value.

12. Apparatus according to claim 10 or 11.

14. The predetermined second value is 20%.

14. The apparatus of claim 13.

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