WO2017005665A1

WO2017005665A1 - High-frequency generator for connecting electrosurgical instruments

Info

Publication number: WO2017005665A1
Application number: PCT/EP2016/065615
Authority: WO
Inventors: Uwe Fischer; Lutz Kersten; Stefan Schiddel; Thomas FAEHSING
Original assignee: Olympus Winter & Ibe Gmbh
Priority date: 2015-07-03
Filing date: 2016-07-01
Publication date: 2017-01-12
Also published as: DE102015212546A1

Abstract

The invention relates to a high-frequency generator (12, 12') for connecting a high-frequency electrosurgical instrument (14), which high-frequency generator can be operated in various operating modes. The high-frequency generator (12, 12') has an internal resistance and/or frequency response that can be varied in a controllable manner.

Description

High frequency generator for connecting electrosurgical instruments

The invention relates to a high-frequency generator for connecting a high-frequency electrosurgical instrument. The high-frequency generator can be operated in different operating modes.

High frequency generators for connecting electrosurgical instruments are known in various forms. Examples can be found e.g. in WO 2010/124785, DE 10 2013 222 800, WO 2010/102620 and WO 2010/142438.

A high-frequency generator and a high-frequency electro-surgical instrument connected thereto form a high-frequency surgical system whose characteristics such as output voltage, output current and thus also the output power depend both on the high-frequency generator and on the high-frequency electrosurgical instrument connected thereto. These characteristics may change if another high frequency electrosurgical instrument is connected to a particular radiofrequency generator.

The aim is to expand the scope of a high-frequency surgical system.

According to the invention, this object is achieved by a high-frequency generator which is to be operated in different operating modes and is characterized in that the High frequency generator has a controllable variable internal resistance and / or frequency response.

The invention includes the recognition that conventional high frequency generators in a particular configuration, i. Depending on the particular operating mode of the high-frequency generator and connected to the high-frequency generator high-frequency electrosurgical instrument, a specific frequency response, a certain internal resistance and thus a certain output impedance (the high-frequency generator) have. This has the consequence that the internal resistance of the high-frequency generator and thus also the output impedance of the high-frequency rurie system are fixed for a particular configuration and can not be changed.

With a high-frequency generator according to the invention, this restriction no longer exists. On the contrary, the internal resistance of the high-frequency generator and / or its frequency response can be controlled by appropriately activating, setting, connecting and / or disconnecting electrical components and / or by setting the stimulation frequency such that predetermined output values, such as current, Voltage or power result. Preferably, the driving, adjusting, switching on and / or off electrical components by the high frequency generator itself takes place. According to one embodiment, the high frequency generator has a bandpass at its output, which is variable, wherein the high frequency generator is formed, the bandpass during operation in an operating mode be changed so that for a respective selected operating mode predetermined output values such as current, voltage or power result. Preferably, the bandpass has an inductivity that is variable or its quality is variable, so that by changing the inductance or the quality of the inductance, an adjustment of the predetermined output values by the high-frequency generator during an operating mode can take place.

Alternatively or additionally, the high-frequency generator may have a transformer with a plurality of primary and / or secondary windings and be configured such that the high-frequency generator performs a switching between individual primary and / or secondary windings such that for a respective selected operating mode predetermined output values such as current, Voltage and / or power result. In a Another variant, the high-frequency generator additionally or alternatively be designed so that an internal resistance by adding a parallel or a serial load at the output of the high-frequency generator is adjustable such that the high-frequency generator predetermined by connecting or disconnecting the serial or parallel load for a respective selected operating mode Output values such as current, voltage or power can be set.

Particularly preferred is a variant in which the internal resistance of the high-frequency generator can be controlled by setting the stimulation frequency such that predetermined output values such as current, voltage or power result for a respective selected operating mode. In this case, the high-frequency generator can in particular be designed so that it adjusts the stimulation frequency, taking into account a frequency response (ie the frequency-dependent internal resistance) of the high-frequency generator and the selected operating mode, that results in a respectively predetermined target internal resistance. In this case, the high-frequency generator can be designed to determine and adjust the control of the stimulation frequency as a function of the frequency response of the entire high-frequency surgical system including the high-frequency generator and the connected high-frequency electrosurgical instrument. According to a particularly preferred embodiment, the high-frequency generator is designed to control the stimulation frequency as a function of a load impedance applied to its output so that the internal resistance of the high-frequency generator increases with decreasing load impedance. Such a falling load impedance occurs, for example, when unwanted sparks or arcs occur during electrosurgical coagulation or cutting, which are to be avoided or erased. In the case of such an arc, the load impedance drops abruptly. If the high-frequency generator then changes the stimulation frequency so that the internal resistance of the high-frequency generator increases, thereby a resulting arc can be deleted.

The embodiment which is designed in accordance with the high-frequency generator to change the stimulation frequency in order to adjust the internal resistance of the high-frequency generator is based on the finding that the frequency response of a high-frequency generator in a respective operating frequency range is not constant and in particular is typically also not linear. Rather, a slight change in the stimulation frequency (output frequency of the high-frequency generator) can lead to a significant change in the internal resistance of the high-frequency generator. This intrinsically undesirable property is in the Hochfre- Frequency generator is used to make specific changes in the Stirn ulationsfrequenz in order to specifically change the internal resistance of the high-frequency generator so that there are desired output values such as current, voltage and / or power. Preferably, the high-frequency generator has at least two operating modes, namely at least one cutting mode for cutting body tissue by means of a high-frequency current and a coagulation mode for coagulating body tissue by means of a high-frequency current.

The high-frequency generator can be designed to determine a respective load impedance (load applied to the high-frequency electrosurgical instrument) and to set the internal resistance as a function of this load impedance. Particularly preferred is a variant in which the high-frequency generator is designed to effect a change in the internal resistance and / or the frequency response by connecting and disconnecting at least one of the electrical components and preferably from at least one of the additional frequency components resulting therefrom in the frequency spectrum of a stimulation frequency. Sidebands) to determine a load impedance. In this regard, it has been recognized that in high frequency generators of the prior art, a load impedance determination has hitherto been carried out exclusively with invariable internal resistance and / or fixed frequency response and thus significant tissue changes such as tissue type or coagulation result based on a few insufficient measurements. By automatically connecting and disconnecting at least one of the electrical components, additional frequency components are introduced into the stimulation frequency as the basis for determining the load impedance. Particularly preferably, the load impedance determination excludes an evaluation of a step response caused by switching on and off of at least one of the electrical components.

Preferably, the change of the internal resistance and / or the frequency response is provided by switching on and off of the at least one of the electrical components exclusively for the determination of the load impedance and / or independently of any provided load matching circuit for adapting the load of the high frequency generator to a high frequency electrosurgical instrument. In a particularly preferred variant, the high frequency generator is free from a load adaptation circuit for adapting the load of the high frequency generator to a high frequency electrosurgical instrument.

The high-frequency generator is preferably designed to generate a stimulation voltage having a stimulation frequency between 200 kHz and 2 MHz and to generate sidebands of preferably +/- 10 kHz by connecting and disconnecting at least one of the electrical components in the frequency spectrum of the stimulation frequency. Particularly preferably, the stimulation frequency remains unchanged by the switching on and off of at least one of the electrical components. In other words, by modulating the stimulation frequency, which is caused by the switching on and off of at least one of the electrical components, sidebands occur in the frequency spectrum of the stimulation frequency.

Preferably, load impedance determination includes measuring the time history of the output values of current and voltage. Preferably, the measurement of the time profile of the output values current and voltage is performed by a measuring module of the high-frequency generator. The measuring module is preferably connected downstream of the at least one of the electrical components. In a particularly preferred variant, the change in the internal resistance and / or the frequency response by switching on and off a serial load at the output of the high-frequency generator takes place for the load impedance determination. The measuring module can be connected downstream of the serial load. More preferably, the high-frequency generator is designed such that the connection and disconnection of the at least one of the electrical components takes place in a clocked manner, wherein the switched-on state corresponds to a pulse duration and the switched-off state corresponds to a pause duration. The pulse-pause ratio is preferably 1: 1. Other pulse-pause ratios are possible. The pulse-pause ratio may be predetermined by a preferably variable pulse width modulation signal, by a maximum length sequence signal (MLS) or a pulse signal.

It is particularly preferable for the at least one of the electrical components to be switched on and off as soon as and as long as the high-frequency generator outputs a stimulation voltage. The high-frequency generator can be configured to determine a respective load impedance both in the switched-on state and in the switched-off state. The high-frequency generator is preferably designed to connect a bipolar high-frequency electrosurgical instrument. In bipolar radiofrequency electrosurgical instruments, both electrodes are located on the instrument for electrosurgical therapy (anode and cathode). In contrast, monopolar instruments have only one electrode pole (anode or cathode) while the counter electrode is typically a large-area neutral electrode.

Furthermore, the high-frequency generator is preferably designed to output a high-frequency output voltage having a stimulation frequency within a frequency range from 200 kHz to 2 MHz. With regard to this embodiment variant, it is advantageous if the high-frequency generator is designed to vary the stimulation frequency within a mode of operation by a maximum of +/- 10 kHz or even +/- 50 kHz in order to set a predetermined internal resistance in this manner.

The invention will now be explained in more detail using an exemplary embodiment with reference to the figure. These show in

Figure 1: a high-frequency surgery system in a schematic representation;

FIG. 2 shows components of a high-frequency generator for the controllable influencing of its internal resistance and / or frequency response;

Figure 3: an example of a frequency response of a high-frequency generator for

Explanation of setting the internal resistance by changing the stimulation frequency; and

Figure 4: Components of a high-frequency generator for controllable influence on its internal resistance and / or frequency response and for load impedance determination.

1 shows a schematic illustration of a high-frequency surgical system 10 having a high-frequency generator 12 and a bipolar high-frequency electrosurgical instrument 14 connected thereto.

The high frequency generator 12 comprises a high voltage supply unit 16 and a high frequency high voltage output stage 18, which is formed by a resonant circuit 20 having at least one inductor 22 and a capacitor 24, and an output transformer 26. The output transformer 26 has a primary winding 28 and a secondary winding 30. The primary winding 28 may also act as the sole inductance of the resonant circuit 20, so that the inductance 22 may be omitted under certain circumstances. A drive unit 32 feeds a DC voltage supplied by the high-voltage supply unit 16 clocked into the resonant circuit 20. The clock frequency corresponds to the desired stimulation frequency.

The output transformer 26 effects a galvanic isolation of the high-frequency resonant circuit from the connections for the high-frequency electrosurgical instrument 14.

FIG. 2 shows some of the components of the high-frequency generator from FIG. 1 as well as possible additional components of the high-frequency generator with which the internal resistance and / or the frequency response of the generator can change during operation in an operating mode and thus can be controlled.

Shown are the high voltage supply unit 16 and a resonance unit 34 and a secondary winding 30 'of a Ausgangsstransforma- not shown. The resonance unit 34 includes the resonance circuit 20 and the output transformer 26.

As another optional component, a variable band-pass 36 is shown as well as a switchable resistor network 38. Both the variable band-pass 36 and the switchable resistor network 38 are optional components that are connected downstream of the secondary winding 30 'of the output transformer but are components of the high frequency generator 12' and of This can be controlled or switched.

The schematic representation of the variable bandpass 36 and the switchable resistor network 38 are each exemplary. For example, the switchable resistor network 38 may also contain only a single resistor 40.1 or 40.2 and also only a single switch 42.1 or 41.2 associated with the resistor.

Both with the variable bandpass 36 and with the switchable resistor network 38, the internal resistance of the high-frequency generator 12 'can be changed in each case. With respect to the band-pass 36, this can be done, for example, by changing an inductance 36.1 of the band-pass 36 in a controlled manner or by changing the quality of the inductance 36.1 goodness.

With respect to the switchable resistor network 38, a change in the internal resistance of the high-frequency generator 12 'is possible because one or more of the resistors 40.1 and 40.2 are switched by means of the switches 42.1 and 42.2 as a parallel or serial load.

Not shown in FIG. 2 is the high-frequency electrosurgical instrument. Instead, an equivalent circuit 44 is shown, which schematically represents the electrical properties of the high-frequency electrosurgical instrument in connection with the respective body tissue.

As a further possibility for influencing the internal resistance of the high-frequency generator 12 ', it is indicated in FIG. 2 that the secondary winding 30' of the output transformer can have several taps, so that the effective inductance of the secondary winding 30 'of the output transformer can be influenced in this way in turn, the resistance and frequency response of the high frequency generator 12 'are controllably variable.

A particularly preferred variant for adjusting the internal resistance of the high-frequency generator 12 'is to specifically change the stimulation frequency of the high-frequency generator for setting a desired internal resistance. The pacing frequency is understood here to mean the frequency with which the resonance circuit 20 is excited by the high-voltage supply unit 16 with voltage pulses, that is, stimulated.

How the internal resistance - or more precisely the output impedance Z - of the high-frequency generator 12 'can be influenced by deliberately changing the stimulation frequency is shown schematically in FIG. Fig. 3 shows a possible frequency response of a high-frequency generator. As can be seen, the frequency response of the high frequency generator is neither linear nor constant. This opens up the possibility of operating the high-frequency generator at a target stimulation frequency f _z between 200 kHz and 2 MHz, for example, and changing this target stimulation frequency f _z by a maximum of +/- Af, eg +/- 10 kHz. In this way, the output impedance Z of the high-frequency generator can be adjusted in the region ΔΖ by varying the stimulation frequency alone. be presented. This possibility of selectively influencing the internal resistance of the high-frequency generator can also be implemented without such components as a variable band-pass filter 36 or a switchable resistor network 38 and also without a secondary winding 30 'with multiple taps. FIG. 4 shows a high-frequency generator 12 'which corresponds to the high-frequency generator described with reference to FIG. The high-frequency generator 12 'is followed by a resistor 40.1, which forms a serial load. By means of a switch 42.1, the resistor 40.1 can be switched on and off.

It should be noted that in the exemplary embodiment illustrated in FIG. 4, the desired sidebands are generated by connecting and disconnecting the resistor 40. 1 as an electrical component. In another embodiment, alternatively or additionally, other electrical components or other electrical components may be used, such as inductors, capacitors, nonlinear components (diodes), etc. The switching on and off is done automatically by the high frequency generator 12 'by means of the clock signal T. , which has a pulse-pause ratio of 1: 1 by way of example. The high-frequency generator 12 'is designed to generate a stimulation voltage with a target stimulation frequency f _z between 200 kHz and 2 MHz and to change this target stimulation frequency f _z by a maximum of 10 kHz by switching the resistance 40.1 on and off. A measuring module 50, which serves to measure the time profile of the output values current and voltage and, as a result, the determination of the load impedance (equivalent circuit 44), is connected downstream of the resistor 40.1.

Indicated on the left of the resistor 40.1 is a frequency spectrum S (0) of a stimulation frequency fz, as would occur without the connection and disconnection of the resistor 40.1. The only significant peak occurs at the pacing rate fz. Indicated on the right of the resistor 40.1 is a frequency spectrum S (+) of a stimulation frequency fz, as occurs with the connection and disconnection of the resistor 40.1. In addition to the significant peak occurring at the pacing rate fz, two smaller peaks occur at the pacing rate fz and fz +, which also serve to determine the load impedance. LIST OF REFERENCE NUMBERS

10 high frequency surgery system

12, 12 'high frequency generator

14 high frequency electrosurgical instrument

16 high voltage supply unit

18 high frequency high voltage output stage

20 resonant circuit

22 inductance

24 capacity

26 output transformer

28 primary winding

30, 30 'secondary winding

32 control unit

34 resonance unit

36 band pass

36.1 Inductance of the bandpass

38 resistor network

40.1, 40.2 resistance

42.1, 42.2 switch

44 equivalent circuit

Z internal resistance / output impedance

Claims

claims

A high-frequency generator for connecting a high-frequency electrosurgical instrument (14), wherein the high-frequency generator (12, 12 ') is to be operated in different operating modes, characterized in that the high-frequency generator (12, 12') has a controllably variable internal resistance and / or Has frequency response.

2. High-frequency generator according to claim 1, characterized in that the internal resistance and / or frequency response is controllably variable independently of a selected operating mode.

3. High-frequency generator according to claim 1 or 2, characterized in that the internal resistance and / or frequency response by appropriate driving, setting, and / or switching off electrical components (30, 30 ', 36, 38) is controllably variable, wherein the driving , Setting, switching on and / or off electrical components (30, 30 ', 36, 38) preferably by the high frequency generator itself.

4. High-frequency generator according to claim 3, characterized in that the high-frequency generator (12, 12 ') is designed for a load impedance determination, a change in the internal resistance and / or the frequency response by switching on and off at least one of the electrical components (40.1) to effect and off at least one of the additional frequency components (fz-fz +) resulting therefrom in the frequency spectrum of a stimulation frequency (f _z ) to determine a load impedance.

5. High-frequency generator according to claim 4, characterized in that the connection and disconnection of at least one of the electrical components (30, 30 '; 36; 38; 40.1) is clocked, the switched-on state of a pulse duration and the switched-off state of a pause duration and wherein the switching on and off of the at least one of the electrical components as soon as and as long as the high-frequency generator outputs a stimulation voltage. 6th

High-frequency generator according to at least one of Claims 1 to 5, characterized in that the operating modes of the high-frequency generator (12, 12 ') have at least one starting mode during which the high-frequency generator generator (12, 12 ') carries out a determination of an impedance present at the output.

High-frequency generator according to at least one of Claims 1 to 6, characterized in that the internal resistance (Z) of the high-frequency generator (12, 12 ') can be controlled by setting the stimulation frequency (f _z ) in such a way that predetermined output values such as current for a respective selected operating mode , Voltage or power result.

High-frequency generator according to claim 7, characterized in that the high-frequency generator (12, 12 ') is adapted to set the stimulation frequency (f _z ) taking into account a frequency response of the high-frequency generator (12, 12') and the operating mode so that a respective predetermined destination - Internal resistance results.

9. High-frequency generator according to claim 7 or 8, characterized in that the high-frequency generator (12, 12 ') is designed to control the stimulation frequency (f _z ) in response to a voltage applied to its output load impedance so that the internal resistance (Z) of the high-frequency generator (12, 12 ') increases with decreasing load impedance.

High-frequency generator according to at least one of Claims 1 to 9, characterized in that the high-frequency generator (12, 12 ') has a bandpass filter (36) at the output of the high-frequency generator (12, 12') which can be varied, the high-frequency generator (12, 12 ') is configured to change the bandpass (36) during operation in an operating mode so as to give predetermined output values such as current, voltage or power for a respective selected operating mode.

High-frequency generator according to claim 10, characterized in that the band-pass (36) has an inductance (36.1) which is variable or whose quality is variable.

High-frequency generator according to at least one of claims 1 to 1 1, characterized in that the high-frequency generator (12, 12 ') has a transformer (26) with a plurality of primary and / or secondary windings (28, 30, 30'), wherein the high-frequency generator ( 12, 12 ') is formed, a switching between individual primary and / or secondary windings (28, 30, 30 ') to be carried out so that predetermined output values such as current, voltage or power result for a respective selected operating mode.

13. High-frequency generator according to at least one of claims 1 to 12, characterized in that the internal resistance and / or frequency response of the high-frequency generator (12, 12 ') by adding a parallel or serial load (40.1, 40.2) at the output of the high-frequency generator (12, 12 ') is adjustable by the high frequency generator (12, 12') depending on a respective operating mode, the serial or parallel load so on or off, that result for a respective selected operating mode predetermined output values such as current, voltage or power.

14. High-frequency generator according to at least one of claims 1 to 13, characterized in that the high-frequency generator (12, 12 ') is adapted to output a high-frequency output voltage with a stimulation frequency (f _z ) within a frequency range of 200 kHz to 2 MHz.

15. High-frequency generator according to claim 14 and at least one of claims 6 to 8, characterized in that the high-frequency generator (12, 12 ') is adapted to vary the stimulation frequency by a maximum of +/- 10 kHz to (Af) to a predetermined internal resistance adjust.