WO2013139945A1

WO2013139945A1 - Device and method for measuring and regulating thermal effects in high-frequency surgeries

Info

Publication number: WO2013139945A1
Application number: PCT/EP2013/056001
Authority: WO
Inventors: Günter Farin
Original assignee: Farin Guenter
Priority date: 2012-03-21
Filing date: 2013-03-21
Publication date: 2013-09-26
Also published as: DE112013001594A5; DE112013001594B4; WO2013139945A9

Abstract

The invention relates to a device or a method with which the resistance of the zone of effect in a monopolar high-frequency surgery can be determined. In this manner, the thermal effects in high-frequency surgeries can be measured or regulated.

Description

Apparatus and method for measuring and controlling thermal effects in high frequency surgery

Technical area

In high-frequency surgery, high-frequency electrical alternating currents can generate thermal effects in biological tissues of patients. These effects can be used, for example, for cutting, devitalizing and / or closing blood vessels or for hemostasis. The invention relates to methods and devices suitable or even required for this, with which the thermal effects can be better controlled, controlled and / or regulated in monopolar HF surgical methods.

State of the art

Surgically useful thermal effects in target tissues are, in particular, the devitalization effect above about 50 ° C., the coagulation effect above about 60 ° C., the desiccating effect, which takes place especially when the boiling temperature of intracellular and extracellular fluids is reached, and the so-called vaporization effect or the pyrolysis from about 200 ° C. By target tissue is meant tissue on or in which at least one of the above thermal effects is to be generated. The heating of the target tissue to the temperature required to produce the respective intended thermal effects is achieved by endogenous and / or exogenous conversion of electrical energy into thermal energy. With endogenous conversion, the conversion of electrical energy into thermal I mean energy in the tissue. Since, in monopolar methods of HF surgery, HF current flows between an active electrode applied to the target tissue and a neutral electrode applied generally on the skin of the patient, ie both through target tissue and through collateral tissue, the conversion takes place both in the target tissue and in the collateral tissue instead of. With exogenous conversion here is meant the conversion of electrical energy into thermal energy outside of the target tissue, in particular in the directed to the respective target tissue electrical arcs or gas plasmas.

The endogenous conversion of electrical energy E _e i into thermal energy E _t h is a well-known physical phenomenon whose quantitative effect can be briefly described mathematically with the following equations:

2 2

Eth = E _e | = U _e ff ^' Uff ^' Ateff = U eff: RT ^' Ateff = 1 eff ^' RT ^' At _e ff

Where U _H Feff is the rms value of the RF voltage applied to the respective tissue, l _H Feff the rms value of the HF current flowing through the respective tissue, R _T the amount of electrical resistance of the tissue in question (Tissue) and At _e ff the effective duration of the HF current means.

Although the exogenous conversion of electrical energy E _e i into thermal energy E _t h in gas plasmas is likewise a well-known physical phenomenon, its quantitative effect can only be described mathematically with the same equation mentioned above because of the complex and stochastic properties of the gas plasmas described here as the endogenous conversion, where, however, U _{H means} Feff arn gas plasma and l _H Feff in the gas plasma. However, the amplitude U _H F _{P of} the HF voltage plays an important role here insofar as the formation of electrically conductive gas plasma or electric arc between active electrodes and aqueous biological tissues only occurs at voltage amplitudes above approximately 200 V _p . Electric arc However, these are prerequisites for the above-mentioned vaporization effect as well as the HF surgical cutting effect.

In monopolar methods of RF surgery, the RF current is known to be directed through relatively small-area contacts between an active electrode or an electric arc or plasma beam and the respective target tissue in the target tissue, such that the HF current divergent depending on the viewing direction of the small-area contact out into the tissue or convergent flows out of the tissue in the small-area contact. The current density consequently decreases with the distance from the small area contact. Since the heating of the fabric is proportional to the square of the current density, the heating of the fabric takes place more rapidly in the contact-near zone than in the contact-distant zone. Incidentally, this is a requirement of monopolar RF surgical procedures and context of the subject of this invention.

Although the control and reproducibility of both the quality and spatial extent of the intended thermal effects in target tissues are critical to the success of RF surgical procedures, no in vivo applicable method for determining the relevant electrical parameters has heretofore been known. To date, only the HF current flowing through the active electrode and the neutral electrode and the HF voltage present between the active electrode and the neutral electrode can be measured in vivo. In order to be able to control the quality and spatial extent of the thermal effects in or on the target tissue, it would be expedient to generate or generate the electrical resistance of the target tissue or, better, the spatial zone in the target tissue in which the thermal effects are to be generated The following Ef- fektzone called to be able to control or determine in vivo.

In order to enable the reproducibility of surgically relevant thermal effects in biological tissues as a function of the RF voltage has been As early as 1976, M. Schneiderman (US 4,092,986, Constant Output Electrosurgical Unit) proposed to automatically regulate the RF voltage to settable setpoint values in a constant manner. The automatic control of the HF voltage in HF surgery was implemented clinically around 20 years ago, following a suggestion by G. Farin (EP 0 316 469 A1, high-frequency surgical device for cutting and / or coagulating biological tissue). The amplitude or a defined mean value of the HF voltage at the output of the HF generator is automatically regulated here, but not where it would be more important, namely at the target tissue or at the electrical resistance of the respective target tissue. If the electrical resistance of the target tissue can be determined in vivo, then the thermal effects in RF surgery applications can be better controlled and controlled manually and / or automatically, and / or regulated.

Presentation of the invention

It is the object of the invention to develop methods and devices suitable for monopolar applications of HF surgery with which the thermal effects in target tissues can be better controlled, controlled and / or regulated. A further object of the invention is to develop devices and methods for detecting, controlling, adjusting, controlling and / or regulating electrical parameters at and / or in the effect zone of target tissues in monopolar applications of HF surgery.

This object is achieved by a method or a device according to one of the independent claims. Advantageous embodiments of the invention are specified in the subclaims. The solution of the problem is based on the knowledge and the consequent postulate that the HF current in monopolar applications of HF surgery intended by a so-called. Active electrode both by the tissue in which the intended thermal effects are to be generated as must also flow through the adjoining tissue to a so-called. Neutral electrode. The tissue in which thermal effects are to be generated, generated or generated is commonly called target tissue (TT / Target Tissue). Target tissue may be, for example, the liver, a tumor or a gut polyp. However, in most cases, the intended thermal effects should not and / or not occur simultaneously at all sites or in all zones of a target tissue and do not actually do so, but generally arise at the site or in the zone of the target tissue, which is contacted by the active electrode and in which the current density for generating the respective intended thermal effects is sufficiently large. The zone of the target tissue in which the intended thermal effects are to be generated or generated is referred to below as the effect zone (EZ Effect Zone). The RF current thus flows successively through the effect zone and through the tissue adjacent to the effect zone, which is referred to below as collateral tissue (CT / collateral tissue), to the neutral electrode.

In the above introduction, this differentiated consideration of the target tissue, namely the postulate of a so-called effect zone in the target tissue, is not considered because this postulate is the basis and actually part of this invention. Accordingly, the inventor defines an electrical resistance R _{EZ of} the effect zone and an electrical resistance R _{CT of} the collateral tissue. With R _EZ is the electrical resistance of the Effekzone between the surface or interface through which the HF current from the active electrode coming into the Ef The term "zone of influence" refers to the interface between the effect zone and the collateral tissue through which the HF current flows out of the effect zone. R _CT is the electrical resistance of the collateral tissue between the interface to the effect zone into which the RF current from the effect zone flows into the collateral tissue and the contact surface between collateral tissue and neutral electrode through which the RF current flows out of the collateral tissue. meant.

The sum of the series resistances R _E z and R _CT corresponds to the so-called load resistance (R _L ), as known in the European Standard EN 60601-2-2 Part 2: Particular requirements for the safety of high-frequency surgical equipment and in International Standards , in particular IEC 601-2-2 is defined. According to these standards, R _L is the electrical resistance that can be measured between the electrical connections of the active electrode and the neutral electrode, that is to say the sum of R _E z and R _CT . However, it is to be taken into account here that the measurements to be made at the beginning or during an operation or at others Way to be determined resistors R _E z and RCT and consequently also R _L do not remain constant during an operation but vary more or less. The magnitude of the effect zone R _{EZ of} the effect zone increases and decreases in particular with the effective magnitude A _eff and shape of the contact area between the active electrode and the effect zone, and also with the temperature of the fabric of the effect zone. The amount of resistance RCT depends in particular on the electrical properties of the skin and the subcutaneous fatty tissue and on the effective contact surface of the neutral electrode with the skin of the patient. The neutral electrode should therefore be applied to the skin of the patient so that as much as possible of the contact surface available on a neutral electrode is electrically conductively contacted with the skin of the patient and remains contacted during the operation. To ensure this are high-frequency surgical devices with Control devices equipped to automatically control the electrical contact between the neutral electrode and the patient. Such a control device is known for example from European Patent EP 0 390 937 Bl. The purpose of these and other known devices for controlling the application of neutral electrodes is not the direct measurement or indirect determination of R _CT - these devices are not provided for this because the above-defined resistance R _CT has not previously been considered, nor readily for this purpose suitable.

Presumably, such a differentiated consideration of the load resistance R _L has not yet been made or has hitherto not made sense, because there was neither a method nor a device for measuring or calculating the serial partial resistances R _CT and in particular R _E z contained in R _L.

Starting from the postulates and definitions of R _EZ , RCT and R _L described above, the resistance R _E z of the effect zone can be calculated as the difference between R _L and R _CT , ie R _E z = RL - RCT.

For this purpose, a device (A) can be used which comprises

• a device for measuring the electrical resistance of biological tissues

• to which at least two separate neutral electrodes, which can be applied to the body and / or extremities of a patient, can be connected, so that the electrical resistance of the at least two neutral electrodes applied to the patient can be measured, and

• to which alternatively a monopolar active electrode and a neutral electrode or several neutral electrodes connected to a neutral electrode can be connected, which relate to a target tissue. can be applied to the body of the patient, so that the electrical resistance of between the applied at the target tissue active electrode and the body applied to the neutral electrode or applied neutral electrodes can be measured, and

A device for switching the connections between the neutral electrodes and / or the active electrode and the device for measuring the electrical resistance of biological tissues, and

An algorithm for calculating the electrical resistance R _E z of an effect zone in the target tissue near the active electrode

This device (A) may be an integral part of a high-frequency surgical device or a separate device for combined use for a high-frequency surgical device.

This device may be applied to or in high frequency surgical devices to control, control, regulate, and / or display electrical parameters at and / or in the effect zone, and / or to derive information about the state of the tissue in the effect zone therefrom.

In this regard, research conducted by the inventor has revealed that in monopolar applications of HF surgery in which the active electrode has a direct electrically conductive contact with the target tissue, the amount of resistance R _E z may be less than the amount of resistance R _CT .

For these investigations, a method was developed with which R _EZ can be determined in vitro and sufficiently well by, as shown schematically in FIG. 6, two identical of the respective active electrodes to be used (AE1, AE2) on or in the respective target tissue identical or comparable to specific electrical resistance at normal body temperature tissue comparable (T / Tissue) are applied in this optimal distance from each other and the electrical resistance between these two active electrodes is measured at the terminals (A _AE i, A _AE2 ) and then divided by 2. By optimal distance is here meant a distance at which the configuration of the electric field in the vicinity of the two identical active electrodes corresponds to that in real application on or in the goat tissue and these two near fields touch each other as directly as possible in the median surface (MP). _Measured with this indirect method between the electrical connections (A _AE i, A _AE2 ), the electrical resistance R _EZ i + R _E z2 _{# is,} for example, between a customary polypectomy snare and a polyp with one at the application parts of the polypectomy snare (eg AE1). measured diameter (d) of 1 cm at normal body temperature about 25 ohms. However, it should be noted that the amount of R _EZ becomes smaller than at body temperature due to the intended temperature rise of the tissue in the effect zone, while the magnitude of the electrical resistance R _CT and R _CT p, respectively, is relatively constant due to only low heating of the tissues concerned remains. As is known, the specific electrical resistance of electrolytes decreases reciprocally in proportion to the temperature of the electrolyte-containing tissue. A temperature increase from approx. 35 ° C to approx. 90 ° C reduces the specific electrical resistance of biological tissues by about half, in the above example in the polypectomy the resistance RJJ thus drops from 25 ohms at 35 ° C to approx Ohm at 90 ° C.

Description of the drawings

The invention will now be described by way of example without limitation of the general inventive idea by means of embodiments with reference to the drawings. Show it: FIG. 1 shows the application of simultaneously at least two neutral electrodes to a patient to determine the amount of R _CT or RCT _p and the amount of R _L or R _Lp

FIG. 2 shows an exemplary embodiment of an apparatus for in vivo measurement of RNEI / NE2 and R _L or R _Lp and for calculating R _CT or R _CT P and R _EZ from the measurement results

FIG. 3 shows an exemplary embodiment of a device for controlling the application of neutral electrodes to the patient and for in vivo measurement of RNEI / NE2 and R _L or R _Lp and for calculating R _CT or R _CT p and R _EZ from the measurement results and for checking , Control, and / or display of the electrical parameters on and / or in the effect zone and / or the state of the tissues in the effect zone and / or on and / or Kollatera lgewebe and / or the state of application of the neutral electrodes on patients.

Figure 4, the applicability of the device shown in Figure 3, even for only a single-surface neutral electrode

Figure 5, the applicability of the device shown in Figure 3, even for only a two-layered neutral electrode

Figure 6 is a graph for describing a method for in vitro measurement of R _E z when using certain active electrodes on certain target tissues.

FIG. 7 is a graph describing the postulate listed above and the definitions introduced there.

FIG. 8 shows the applicability of the device shown in FIG. 3 also for two single-surface neutral electrodes. The above-described postulate as well as the above-mentioned definitions which are the basis of this invention can be explained with reference to FIG. In Fig. 7, a patient (P), largely reduced to the essentials, shown. On the skin (H) of the patient P, a neutral electrode (NE) with a connecting cable (K _NE ) is applied. An active electrode (AE) is applied to a target tissue (TT) to produce a thermal effect at that site of the target tissue by introducing an RF current (I _H F). The RF current flows from the active electrode (AE) divergent into the target tissue (TT) and further diverging through the collateral tissue (CT) to the neutral electrode (NE). The surgeon only cares about the intended thermal effect in the target tissue. However, the intended thermal effects do not occur simultaneously in the entire target tissue and are usually not intended to do so. The zone of the target tissue in which the intended thermal effects should and can or may arise or have already developed is called an effect zone (EZ). In order to be able to control, control and or regulate the intended thermal effect in vivo in the effect zone, it is necessary, for example, to determine the electrical resistance (R _E z) of the effect zones EZ, ie the electrical resistance of the tissue between the active electrode AE and the imaginary interface between effect zone EZ and target tissue TT or collateral tissue (CT) to which the target tissue belongs or know in vivo. R _EZ can be determined in vivo as the difference between R _L and R _CT , if the electrical resistance of the tissues between the active electrode and the neutral electrode, which is known as the load resistance R _L and is directly measurable in vivo, and the electrical resistance R _CT collateral tissue CT, dominated by subcutaneous fat tissue (FT) in particular, knows what is rarely the case or identifies what has not been possible so far. How this can now be done in vivo will be described with reference to FIG.

The amount of electrical resistance R _CT or R _CTp can be measured and determined in vivo indirectly and with sufficient accuracy, as shown in FIG shown schematically, at least one neutral electrode (N E1, NE2) as symmetrical, in particular mirror-symmetric and equidistant to the sagittal plane SP (Sagittal Plane) is applied to the patient P, for example, each a neutral electrode on the left and one on the right thigh of the patient th, if the target tissue TT lies in the lower region of the body, or one neutral electrode on the left and one on the right upper arm when the target tissue TT is in the upper region of the body (not shown in FIG. 1), and by the measured amount of electrical resistance R _NE i / NE2 between the electrical connections A _NE i, A _{NE2 of} these two neutral electrodes is measured and divided by 2, which is the electrical resistance (RNE / SP) between each of the two neutral electrodes N E1 or N E2 and the imaginary

Sagittal plane SP and sufficiently well the amount of resistance R _CT i or RCT2 between one of the two neutral electrodes (N E1 or NE2) and the effect zone EZ1 on or in the target tissue TT1 corresponds. If the two neutral electrodes NE1 and NE2 and consequently also the two resistors R _CT i or R _N EI / SP and RCT2 or RNE2 / SP are _{connected in} parallel to a resistor R _CTp , that is to say R _CTp = Ren, then the value of the resistor becomes halved between the two neutral electrodes connected in parallel and the effect zone compared to the space between only one neutral electrode and the effect zone. This amount corresponds to exactly the amount of R _CTp - (Note: it makes no sense to measure RNEI / NE2 to calculate R _CT or R _CTp and then remove one of the two neutral _electrodes from the patient, and thereafter thermal effects in the effect zone, especially since then any changes of RCT are no longer detectable.) Both theoretical and experimental studies have confirmed that the method described above for determining the amount of R _CT p can also be applied in cases where the Target tissue or the effect zone is not exactly in the sagittal plane SP. The different cases in these cases The amounts of the resistors RNEI / SP and RNE2 / SP are largely compensated by their parallel connection.

Measured by the indirect method described above, the electrical resistance R _{CT is} about 30 to 50 ohms for a currently available neutral electrode and only one of which is properly applied to the skin of a patient's thigh and up to 100 ohms for patients with a massive undercut dermal fat layer , If the contact surfaces of both neutral electrodes N El and N E2 are interconnected to form a total neutral electrode N Ei ₊₂ = N El + N E2 or the two resistors RNEI / SP and R _N E2 / SP are connected together to form a parallel resistor (RCTP) R _CT p at normal tissue temperature about 15 to 25 ohms, with massive subcutaneous fat layer about 50 ohms.

For comparison, the electrical resistance of the effect zone, as already mentioned above in the introduction, in the endoscopic polypectomy of a polyp with a diameter of 1 cm at normal body temperature only about 25 ohms and at 100 ° C, ie the temperature the EZ, which is achieved in HF surgical cutting in the effect zone, only about 15 ohms. The method by which these resistances were measured in vitro is shown and described as an intermediate reference with reference to FIG. 6 in the following paragraph. The method shown schematically in FIG. 6 for the in-vitro determination of R _EZ can be used with any resistance or impedance measuring device with which the electrical resistance of electrolyte-containing biological tissue can be measured. For this purpose, two identical active electrodes AE1 and AE2, in this example two polypectomy loops, are applied at a slight distance from each other around a polyp-like and polyp-like tissue, and the amount of electrical resistance of the tissue between these two active electrodes is measured at the respective tissue temperatures of interest. Hereby, There are two identical effect zones EZ1 and EZ2, so that the amount of resistance of one of these two effect zones is equal to half of the measured amount. This in vitro method can, of course, be applied to various types of tissue and with different active electrodes and also at different tissue temperatures and tissue conditions and is also suitable for checking the in vivo method according to the invention.

From the above comparison of the amounts of R _CT and R _E z occurring in practice, it follows that when only one neutral electrode is applied to the patient, only a small fraction of the electrical voltage, power or energy generated by the RF generator is applied to the patient Effect zone arrives. Therefore, it is important that the amount of R _{CT is} as small as possible. Consequently, it is advantageous to simultaneously apply at least two neutral electrodes on the same patient instead of a neutral electrode and to connect them in parallel to a resistor R _CT p. So far, it is state of the art, because the application of two neutral electrodes is already known. The previous purpose was to avoid thermal damage to the skin under the neutral electrode. Since the introduction of neutral electrodes, which are stuck to the skin, this purpose is obsolete.

This representation should i.a. show that the subject matter of claim 2 can be seen not only as an independent invention, but also as a further embodiment of the subject invention of claim 1.

Of course, the neutral electrodes should be properly applied to the patient with regard to the smallest possible amount of the resistance R _CT p and remain during the entire treatment period. Particularly advantageous for this purpose, as shown schematically in Figure 2, the application of two neutral electrodes (NE1, NE2), each with at least two electrically mutually insulated partial contact surfaces (NEla, NElb, NE2a, NE2b), the same the same time applied to the same patient P, and the application by measuring the electrical resistances Ri _a / 2a-Ria / 2b _# Rib / 2a and Rib / 2b between (/) the partial contact surfaces (NEla / NE2a, NEla / NE2b, NElb / NE2a , NElb / NE2b) of these neutral electrodes. In this case, the inventive method takes advantage of the fact that the relative dependence of the resistance change AR _N E / SP of the change AA _eff the effective contact area A _eff on a partial contact surface, eg A _NE i _a , based, ie

AR _N Ela / SP = f (ΔΑ _ef f)> AR _NE 1 / SP = f (AAeff) is greater than the total contact area A _NE i. The more partial contact surfaces the entire contact surface of the neutral electrodes are disassembled, the better the control of the ratio of the effective contact surface to the available contact surface of the neutral electrodes.

When the measurement of the electrical resistances (R _{1 a} /? _A , Ri _a / h h Rih / _a and Ri _h 2b) between the partial contact surfaces (NEla / NE2a, NEla / NE2b, NElb / NE2a, NElb / NE2b) of Neutral electrodes (NE1, NE2) show that the amounts of these resistors are sufficiently low, and that, moreover, the amounts of the resistances measured between the partial contact areas of the neutral electrodes (NE1, NE2) applied mirror-symmetrically to the sagittal plane (SP) of the patient P are largely identical (Ri _a / 2a = R ia / 2b = Rib / 2a = Rib / 2b), it can be assumed that all partial contact surfaces (NEla, NElb, NE2a, NE2b) and consequently also the available total contact surfaces (NEla + NElb, NE2a + NE2b) of the neutral electrodes (NE1, NE2) are optimally applied In this state, the respective partial contact areas of the neutral electrodes can be connected together to form an overall contact area (NEla + NE1b, NE2a + NE2b) and thus the electrical resistance (R (i _{a +} ib / 2a + 2b)) between the total contact surfaces (NEla + NElb) of the neutral electrode NE1 and (NE2a + NE2b) of FIG Neutral electrode NE2 are measured in order to calculate the resistances R _CT and R _CT P as follows:

RCT = R (ia + ib / 2a + 2b): 2 = RCTS: 2

RCTP = R (ia + ib / 2a + 2b): 4 = R CTS: 4 provided that, for example, two neutral electrodes (NEl, NE2) are sufficiently mirror-symmetrical to the patient's sagittal plane (SP), for example on the left and right thighs, the left one and right hip, the left and right upper arm, etc. applied.

The amount of resistance R _CT P thus determined is not limited, as shown in FIG. 1, to effect zones which are located precisely in the sagittal plane (SP), but also largely applicable to effect zones located outside the sagittal plane, because the parallel connection resistors RNEI / EZ and RNE2 / EZ sufficiently compensate the unbalanced localization of EZ.

A device suitable for this purpose consists, as shown schematically in FIG. 3, of a measuring device (10) for measuring, for example, the electrical resistances Ri _a / 2a-Ria / 2b _# Rib / 2a and Rib / 2b between the part contact ^surfaces (FIG. NEla / N E2a, N Ela / NE2b, NElb / N E2a, NElb / N E2b) and R ₍ i _{a +} ib / 2a ₊ 2b> between the total contact areas (NEla + N Elb / N E2a + N E2b) of, for example, two Neutral electrodes N El and NE2, leads (11, 12, 13, 14) and switches (a, b, c, d, e) and / or adapters or the like (not shown in Fig. 3) for connecting and / or disconnecting Contact surfaces or partial contact surfaces of the neutral electrodes with or from the measuring device (10) or an RF generator (15).

Since it is known that a resistor can not be measured directly, but must be calculated or derived according to Ohm's law R = U: I from a measured voltage (U) and a measured current (I) a measuring device for measuring the electrical resistances, here between the contact surfaces of neutral electrodes and / or their partial contact surfaces, as known for example from the patent EP 0 390 937, from a voltage source and a current sensor, the one of the amount of the respective resistance or the Control current influenced by it (1 _k ) provides proportional electrical signal. When using a constant voltage source (U _k = const.), The control current I _{k is} directly proportional to the resistance R. If the control voltage (U _k ) is not constant, a voltage sensor is also required and the amount R _{k of} the respectively controlled resistance must be calculated in accordance with Ohm's law R _k = U _k : l _k . Since the resistances to be measured here are formed by biological tissues, it is expedient to carry out the measurement with alternating voltage at a sufficiently high frequency at which no polarization and / or electrolysis effects occur at the electrodes. In an advantageous embodiment, this device is equipped with an electronic processor or computer (CPU) to which the parameters supplied by the current and / or voltage sensors of the measuring device (a = i _m , b = u _m ) for calculating, for example, the resistors Ri _a / 2a-Ria / 2b _# Ri _b / 2a and Ri _b / 2b. In addition, the electronic processor or computer can be operated with software with which an evaluation of the parameters supplied by the measuring device (a = i _m , b = u _m ) and / or the resistances Ri _a / 2a _# Ria / 2b calculated from this _# Rib / 2a and Rib / 2b can be performed, for example, with respect to the criterion Ri _a / 2a = Ria / 2b = Rib / 2a = Rib / 2b, and then, if the evaluation corresponds to the respectively defined criteria, the calculation, in particular, of R _CT or R _CT p, for example, according to the equations listed above, can be performed. Suitable hardware and software for this purpose are known to the person skilled in the art, so that a description thereof appears to be dispensable.

This device can be replaced by additional switch (fl, f2), with which the active electrode (AE) can be connected either to the HF generator (15) or to the measuring device. tion (10) can also be used to measure the so-called load resistance (R _L ) and thus also as follows to calculate R _EZ as a difference of R _L and RCT or R _CT p:

REZ = RL - RCT or R _EZ = R _L - R _CTP · In this way, the amount of R _{EZ can} also be determined in vivo both before activation, as well as in pauses or interruptions of the activation of the RF generator. This results in the possibility of the amount and / or changes in the amount of electrical resistance R _EZ the effect zone of the target tissue before, during interruptions and / or after the activation of the RF generator or before, during interruptions and / or after the application To control electrical energy in the target tissue and to derive conclusions about the state or to changes in the state of the tissue in the effect zone of the target tissue.

This device shown in FIG. 3 can be further configured as follows. For example, the measured resistances Ri _a / 2a-Ria / 2b _# Rib / 2a and Rib / 2b or R _L, etc., and determined resistances such as R _CT or R _CT P and / or R _EZ or results of the evaluation of these resistors or even To indicate the state or changes in the state of the tissue in the effect zone or the target tissue, the processor (CPU) can also be used to generate display (m), warning (s) and / or condition signals (o), the Display devices (16), warning devices (17) and / or Statea display devices (18) are passed.

Display devices (16) can be, for example, alphanumeric or graphic displays. Warning devices (17) may be, for example, acoustic and / or visual warning signals generating elements. Status indicators (18) may be, for example, graphic displays or monitors.

With appropriate software, the processor (CPU) may also be used to generate control signals (r, s) for controlling, in particular, the rf generator (15) and / or the o.g. Switch (a, b, c, d, e, f) are used when the switches, for example, by relays (A, B, C, D, E, F, not all shown in Figure 3) are realized, in a specialist In the field of electrical engineering known manner and therefore briefly as a block (19) shown assembly are summarized and need not be described in more detail. In addition, this device can additionally be equipped or operated with software programs (20) for controlling, controlling and / or regulating the electrical parameters in or on the effect zone, for automatically controlling the resistance measurements and activations of the HF generator etc.

If the device described with reference to FIG. 3 is integrated into HF surgical devices which are not used exclusively for applications in which the HF voltage U _H FEZ must be automatically regulated or in which the amounts of R _E z are sufficiently large Compared to the amounts of R _CT , then this device, as already considered in Figure 3, can also be designed so that they can also be operated as conventional control devices with only a two-surface neutral electrode or with one or two single-surface neutral electrodes , For this purpose, either the connection sockets (21, 22, 23, 24) are designed such that only one single-surface neutral electrode (FIG. 4) or only one double-surface neutral electrode (FIG. 5) or two single-surface neutral electrodes (FIG. 8) are connected to the connection sockets, for example 22 and 23 are connectable. In addition, this device offers even more connection and / or combination options of neutral electrodes and their connection to this control device. Here it may be appropriate to design and / or to mark and / or to encode the connection sockets and plugs in such a way that only combinations as intended are possible.

A well-known problem of monopolar methods of HF surgery is the unsatisfactory control and reproducibility of each intended in the effect zone of a target tissue, as well as the avoidance of each in the target tissue or in the effect zone and / or in the collateral tissue unintentional thermal effects. After the measurement of the magnitude of the load resistance R _L and the determination of the amounts of the resistances R _CT and R _CT p and hence the amount of R _E z as described above is possible, various known monopolar methods of HF surgery can be improved and as follows new methods are developed, for example, the development of a method and a device suitable for this purpose for setting and / or automatic control or regulation of the setpoint U _E zsoii the RF voltage at the effect zone. The manual adjustment and / or automatic control or regulation of the setpoint value U _EZso n, for example, the amplitude of the HF voltage U _EZ at the effect zone EZ or the time setpoint course U _E zsoii = f (t) at the effect zone can be achieved by manual adjustment and / or automatic control of the RF output voltage (UG) of the HF generator (15), for example, according to the function U _G = U _EZs0 || : (R _L - R _CT p) ^' R _L = U _EZso n: R _EZ ^' R _L or by manual adjustment and / or automatic control of the HF output current (l _G ) of the HF generator, for example, according to the function

IU: (RR) = U _E zsoii: R be carried out in such a way that the HF voltage (U _EZ ) on or in the effect zone manually or automatically to the respectively intended or in each case on the HF Generator preset setpoints U _E zsoii or temporal setpoint course U _EZ- soii = f (t) can be controlled or regulated.

Furthermore, based on a method and a device suitable for this purpose for the controlled application of electrical energy, a target tissue or into an effect zone can also be realized.

Controlled application of the dose or set amount E _E zsoii of electrical energy (E) required to produce beaten thermal effects in a target tissue or an effect zone of a target tissue can be performed, for example, according to the function E _EtsS oll = iGeff ^{2 '} (R | _ ^" RCT). be done ^'Δΐ = l _Ge ff ^2' R _EZ ^'Ät _e ff in such a manner that the effective value l _Eze ff of the RF current I _DC, the resistance R _DC of the effect zone EZ and the effective duration of current flow Ät _e measured ff and in accordance with this function is calculated. the effective value l _Eze ff of the RF current I _DC, which is identical to the effective value l _Ge ff of the RF output current I _G of the RF generator G, and the effective duration of current flow Ät _e ff can as required as a parameter on HF generator or a device provided for this purpose are manually set on or in the HF generator and / or, for example, manually or automatically controlled as a function of other parameters For example, a desired amount E _EZso n of electrical energy E required to produce intentional thermal effects in an effect zone can also correspond to the function

EEZSOII = (U _G eff: L) ^{2 '} REZ ^' At _e ff done in such a way that the effective value U _Ge ff of the RF output voltage U _{G of} the RF generator 15, the resistance R _{EZ of} the effect zone EZ and the effective Current flow time et _e ff et measured and E _EZso n calculated according to this function. The effective value U _Ge ff of the RF output voltage U _G of the RF generator 15 and the effective duration of current flow Ät _e ff can be adjusted manually according to requirements as parameters at the RF generator 15 or use a dedicated device on or in the RF generator and / or For example, be controlled manually or automatically depending on other parameters.

The controlled application of an EZ required to produce the intended effect of thermal effects in a zone energy E M or the _EZSO be provided by the RF generator of this electrical energy E _G can examples play, also in accordance with the functions

E = E R R respectively

E _G = U _Ge ff. _Ge ff. Et _e ff = E ^' RR be carried out in such a way that R _L and R _EZ are measured or calculated according to the above-mentioned method and that the to be provided by the RF generator 15 or provided energy E _G by measuring, displaying and manual adjustment and / or by automatic control or regulation of the parameters U _Ge ff, _Ge ff and / or Et _e ff _e can be controlled or controlled. Furthermore, based on the above-mentioned findings, a method and a device suitable therefor for controlling R _E z and in particular for automatically switching off the HF current or the HF generator upon reaching a desired value or a defined state or a defined change of R _E z are derived. The control of the electrical resistance R _E z or the control of changes in this resistance due to thermal effects in the respective effect zone EZ, for example in the monopolar thermal hemostasis, for example, according to the function R _EZ = RL - RCT or AR _EZ = AR _L - Ra ^¬ done in such a way that R _L and R _CT are measured or calculated according to the above method and that R _EZ and / or _{EZ EZ} are displayed and / or the HF current or the RF generator can be switched off or switched off when a setpoint R _E zsoii or a defined limit value or setpoint or limit value range of R _{EZ is} reached or exceeded or fallen below.

A further embodiment of the invention relates to the use of the device described above according to FIG. 3 for a method and device suitable therefor for setting and / or automatically controlling or regulating the setpoint value UEZsetpoint of the HF voltage at the effect zone.

The manual setting and / or automatic control or regulation of the setpoint U _EZso n, for example, the amplitude of the RF voltage U _EZ at the effect zone EZ or the time setpoint course U _EZSO II = f (t) at the effect zone can be by manual adjustment and / or automatic control of the RF output voltage (UG) of the RF generator (15) eg according to the function

UG = U _EZS0 || : (R _L - RCT _p ) ^' RL = U _E z _S oii: REZ ^' RL or by manual adjustment and / or automatic control of the RF output current (l _G ) of the HF generator, for example, according to the function I _G = UEZSOII: (RL - RCT) = U EZSOII: REZ be done in such a way that the RF voltage (U _E z) on or in the effect zone manually or automatically to the respective intended or respectively preset at the RF generator setpoints U _E zsoii or temporal setpoint course U _EZ- soii = f ( t) can be controlled or regulated. Another aspect of the invention relates to the use of the device described above according to FIG. 3 for a method and a device suitable for this purpose for the controlled application of electrical energy, a target tissue or an effect zone.

Controlled application of the dose or desired quantity E _EZSO II of electrical energy (E) required to produce beaten thermal effects in a target tissue or an effect zone of a target tissue can be carried out, for example, according to the function

E = Iceff ^{2 '} (RR) ^' At = 1 _Ge ff ^{2 '} R _E z ^' At _e ff in such a way that the effective value l _E zeff of the HF current l _E z, the resistance R _{EZ of} the effect zone EZ and the effective current flow time _e ff et measured and calculated according to this function. The effective value of l _Eze ff of the RF current I _DC, which is identical to the effective value l _Ge ff of the RF output current I _G of the RF generator G, and the effective duration of current flow At _eff can as needed as a parameter to the HF-generator or A device provided for this purpose can be set manually on or in the HF generator and / or manually or automatically controlled, for example, depending on other parameters.

The controlled application of a desired amount E _EZS oii of electrical energy E required for the production of intended thermal effects in an effect zone can, for example, also correspond to the function

E - (Uceff ^: R) ^{2 '} R ^' At _e ff in such a way that the effective value U _Ge ff of the HF output voltage U _{G of} the HF generator 15, the resistance R _{EZ of} the effect zone EZ and the effective current flow time Et _e ff measured and E _EZso n is calculated according to this function. The effective value U _Ge ff of the RF output voltage U _G of the RF generator 15 and the effective duration of current flow Ät _e ff can be adjusted manually according to requirements as parameters at the RF generator 15 or use a dedicated device on or in the RF generator and / or For example, be controlled manually or automatically depending on other parameters.

The controlled application of a fect intended for generating thermal ef- effect in a zone EZ required energy E M or the _EZSO be provided by the RF generator of this electrical energy E _G can for example also according to the functions

E = E ERR or _G = U ff _Ge · l · _G eff Ät _e ff = E _E Zsoll ^'R | _: RIT done in such a way that R _L and R _EZ be measured according to the above method and calculated that the energy E _{G to} be provided or provided by the HF generator 15 can be controlled or checked by measuring, displaying and manually setting and / or by automatically controlling or regulating the parameters U _Ge ff, _Ge ff and / or Et _e ff ,

A further aspect of the invention relates to the use of the device described above according to FIG. 3 for a method and a device suitable therefor for checking REZ and, in particular, for the automatic disconnection of the HF current or the HF generator upon reaching a setpoint value or one defined state or a defined change of REZ. The control of the electrical resistance R _E z or the control of changes in this resistance due to thermal effects in the respective effect zone EZ, for example in the monopolar thermal hemostasis, for example, according to the function R _EZ = RL - RCT or AR _EZ = AR _L - Ra ^¬ done in such a way that R _L and R _CT are measured or calculated according to the above method and that R _EZ and / or _{EZ EZ} are displayed and / or the HF current or the RF generator can be switched off or switched off when a setpoint R _E zsoii or a defined limit value or setpoint or limit value range of R _{EZ is} reached or exceeded or fallen below.

The technical implementation of the above developments of monopolar RF surgical procedures are certainly unproblematic for a person skilled in the art with knowledge of the necessary and disclosed above devices and algorithms. Of course, the methods and devices of this invention may also be used for other purposes.

Claims

claims

1. A method for determining the electrical resistance (R _EZ ) of an effect zone (EZ) in a biological target tissue (TT) of a patient (P) in which thermal effects are to be generated, generated or generated when monopolar high-frequency surgical procedures are used, comprising the steps:

Application of at least one neutral electrode (N E1, N E2) in mirror symmetry to the sagittal plane (SP) of the patient;

- Measurement of the electrical resistance (R _N EI / NE2) between the neutral electrodes (NE1, NE2) applied mirror-symmetrically to the sagittal plane (SP) of the patient on the patient;

- Parallel or interconnecting the neutral electrodes (N E1, N E2) to a total neutral electrode (N Eg);

- Compute the electrical resistance (R _CT ) between the total neutral electrode (NEg) and the sagittal plane (SP) accordingly

RCT = 0.25 (RN E1 / NE2);

- Application of at least one monopolar active electrode (AE) at or in the effect zone (EZ);

- Measurement of the electrical resistance (RL) between the at least one active electrode and the total neutral electrode (N Eg);

- Determining the electrical resistance (R _EZ ) from the difference of (R _L ) and (R _CT ) accordingly

2. Method for controlling the application of at least two separate neutral electrodes (N E1, N E2) to a patent (P) for the application monopolar high-frequency surgical method, wherein the neutral electrodes (NE1, NE2) each have at least two mutually electrically isolated contact surfaces (NEla, NElb, NE2a, NE2b), comprising the method steps:

Measuring at least the electrical resistances between the contact surfaces NEla and NE2a and between the contact surfaces NElb and NE2b and / or between the contact surfaces NEla and NE2b and between the contact surfaces NElb and NE2a;

- Compare the measured electrical resistances.

3. The method according to claim 2, characterized in that the amounts of the measured resistances are displayed visually.

4. The method according to claim 2, characterized in that at a defined deviation of the amounts of the measured resistances visual and / or audible warning signals are generated and / or the activation of an RF generator is disabled.

5. A method for determining the resistance R _EZ according to claim 1 comprising the steps according to claim 2.

6. Apparatus for carrying out the method according to one of claims 1 or 3 to 5 comprising:

- A measuring device for or in a high-frequency surgical device with at least one high-frequency generator for measuring electrical resistance;

- A switching device for or in a high-frequency surgery device for selectively electrically conductive connection of the contact surfaces of neutral electrodes and / or with the measuring device or for parallel connection of all contact surfaces of the neutral electrodes to an overall neutral electrode (NEg) and / or to the electrically conductive connection of at least one active electrode and the total neutral electrode (NEg) with the measuring device or with the high-frequency generator.

Apparatus for carrying out the method according to claim 2 comprising:

- A switching device for or in a high-frequency surgical device for selectively electrically conductive connection of the contact surfaces of neutral electrodes with the measuring device or with the high-frequency generator.

Apparatus according to claim 7 with a measuring device for measuring electrical resistances and a switching device for selectively viewing individual segments (1a, 1b, 2a, 2b) to the measuring device.

Apparatus according to claim 7 or claim 8, characterized in that the switching device switches several or all segments electrically parallel.

Device for displaying R _CT , R _L and / or R _EZ or the electrical energy applied in an effect zone according to one of Claims 7 to 9.

Apparatus according to any one of claims 7 to 10, including an HF surgical generator.

12. The apparatus of claim 11 with automatic control / regulation of the RF voltage at the effect zone

13. The apparatus of claim 11 or 12 with automatic dosing

electrical energy in the effect zone.

14. Device according to one of claims 11 to 13 with automatic termination of a so-called soft coagulation in response to the change of R _EZ .

A method of controlling, controlling or regulating the desired RF voltage (U EZ _SO II) at an effect zone (EZ) in a target tissue (TT) in monopolar RF surgical procedures comprising:

- A method according to claim 1 for determining the electrical resistance (R _E z) of the effect zone (EZ);

a device 25 for measuring the HF output voltage U _{G of} the HF generator 15

a CPU for calculating the required HF output voltage U _G for controlling, controlling or regulating the desired HF voltage UEZ _SO II at an effect zone EZ according to an algorithm

UG = UEZSOII: (RL-RCT) x RL = U _E zsoii: RZE X RL

or

a CPU for calculating the required RF Ausga ngsstroms l _G for controlling, controlling or regulating the RF target voltage U _E zsoii at an effect zone EZ according to an algorithm

IG = U EZSOII: (RL-RCT) = U _E zsoii: RZE A method of controlling, controlling or metering the electrical energy to be applied to an effect zone, or has been, comprising:

a method according to claim 1 for determining the electrical resistance REZ of the effect zone EZ;

- means for measuring the rms value of the rf current through the effect zone;

a CPU for calculating the required electrical energy E _G which must be applied to the load resistor RL in order to apply the electrical energy E _E zsoii to the effect zone, according to an algorithm

E _G = Ug _e ff xl _Ge ff Delta t _eff ;