System for closed loop monitoring of monopolar electrosurgical apparatus

ES 2 327 005 T3

DESCRIPTION

System for closed-circuit surveillance of a monopolar electrosurgical device.

Priority claim

This application claims the priority of US Provisional Application No. 60 / 761,440, entitled “System and method for closed-circuit surveillance of a monopolar electrosurgical device,” presented by Robert Wham et al. On January 24, 2006.

Background

1. Field

The present disclosure relates generally to an electrosurgical method and system, more specifically, to a system for closed-loop surveillance of a monopolar electrosurgical apparatus to perceive energy and tissue properties and control energy delivery based on on perceived properties.

2. Description of Related Art

Electrosurgery involves the application of high radio frequency electrical currents to a surgical site to cut, destroy, or coagulate tissue. In monopolar electrosurgery, a source or active electrode delivers radio frequency energy from the electrosurgical generator to the tissue and a return electrode transmits the current back to the generator. In monopolar electrosurgery, the source electrode is typically part of the surgical instrument held by the surgeon and applied to the tissue to be treated. A patient return electrode is located remote from the active electrode, to transmit current back to the generator.

In bipolar electrosurgery, one of the electrodes of the handled instrument functions as an active electrode and the other as a return electrode. The return electrode is located very close to the active electrode (power supply), in such a way that an electrical circuit is formed between both electrodes. Commonly, the electrodes, in bipolar electrosurgical systems, are arranged within electrosurgical forceps which, by themselves, lend themselves particularly well to closing vessels. In this way, the applied electrical current is limited to the body tissue between the electrodes. When the electrodes are separated far enough from each other, the electrical circuit is opened and thus inadvertent contact of body tissue with either of the separated electrodes does not cause current to flow.

Electrosurgical generators are capable of producing a variety of electrical waveforms. Certain waveforms are more suitable for specific electrosurgical procedures. A continuous waveform with a 100% duty cycle is more suitable for cutting tissue, as the energy generates heat very quickly, thereby vaporizing the tissue. An intermittent waveform, with a duty cycle of approximately 10%, is more suitable for coagulating tissue, since the amount of heat generated is small.

The parameters that commonly affect the coagulation waveform are set manually by the surgeon. This tuning process is complicated as it may be necessary to continually adjust the coagulation waveform during delivery. However, no systems are available that can automatically adjust the coagulation waveform.

US 5,370,645 describes an electrosurgical processor cited as relevant to the present invention during the granting of this patent.

Summary

The present disclosure provides an electrosurgical system equipped with closed-loop surveillance. The system includes an electrosurgical generator having an RF output stage to generate electrosurgical waveforms suitable to achieve coagulation, and a microprocessor to control the RF output stage. Closed-loop surveillance includes a sensor to sense one or more properties of the tissue, such as voltage, intensity, temperature. The sensor transmits data regarding the properties of the tissue to the microprocessor, which adjusts the output of the generator. More specifically, the generator adjusts the electrosurgical waveforms in response to the data to correspond to predetermined waveform parameters.

Also described is an electrosurgical system configured to provide automatic closed-loop control of RF energy in direct response to sensed changes in tissue until a desired clinical effect of hemostasis is achieved. The system includes a generator that has a high-speed, high-voltage power supply (“HVPS”) to power a direct current (“DC”) output. The HVPS is configured to adjust the DC output quickly and dynamically. The generator includes an RF output stage that is configured to generate radio frequency ("RF") energy, comprising one or more waveforms for electrosurgical coagulation, suitable for coagulating tissue. The system also includes an RF sensor for sensing properties of RF energy and generating an RF signal indicative of RF energy. Regimes

ES 2 327 005 T3 perception sampling are sufficient to allow the generator to model the waveforms for electrosurgical coagulation in real time based on the signal from the RF sensor in order to match the waveforms for the RF stage. The system further includes a closed-loop control system that controls the waveform for electrosurgical coagulation. In addition, the system includes one or more gain controllers configured to amplify the RF sensor signal to maintain a predetermined signal-to-noise ratio and to provide RF voltage and intensity correction of the RF sensor signal that It is then transmitted to the controller to allow the modification, in real time, of the RF energy.

In accordance with one aspect of the present invention, there is provided an electrosurgical system according to claim 8, including a generator configured to generate waveforms for electrosurgical coagulation. The generator includes a closed-loop control system that controls waveforms for electrosurgical coagulation. The closed loop control system includes a sensor configured to sense a tissue property or energy property and to transmit the tissue property or energy property as one or more sensor signals having an amplitude. The control system also includes a gain controller configured to process the sensor signals to reduce their amplitude and obtain a signal-to-noise ratio of the sensor signals within a predetermined range. The microprocessor is coupled to the generator and is configured to adjust the waveforms for electrosurgical coagulation based on the sensor signals.

In accordance with another aspect of the present invention, there is provided a closed-loop control system for controlling waveforms for electrosurgical coagulation in accordance with claims 1 and 2. The closed-loop control system includes a sensor configured to sense a property. of a tissue or energy property and to transmit the tissue property and energy property as one or more sensor signals having an amplitude. This control system also includes a gain controller configured to process the sensor signals to reduce their amplitude and obtain a signal-to-noise ratio of the sensor signals within a predetermined range. The microprocessor is coupled to the generator and is configured to adjust the waveforms for electrosurgical coagulation based on the sensor signals.

Also contemplated in the present disclosure is a method of controlling waveforms for electrosurgical coagulation. The method includes the steps of perceiving a property of a tissue or a property of energy and transmitting the property of a tissue or a property of energy as sensor signals having an amplitude, and treating the sensor signals to reduce their amplitude and obtaining a signal-to-noise ratio of the sensor signals within a predetermined range. The method also includes the step of adjusting the waveforms for electrosurgical coagulation based on the signals from the sensor.

Brief description of the drawings

The foregoing and other aspects, features, and advantages of the present invention will become more apparent in light of the following detailed description when taken in conjunction with the accompanying drawings, in which:

fig. 1 is a schematic block diagram of an electrosurgical system;

fig. 2 is a schematic block diagram of a generator in accordance with the present disclosure; and figs. 3A-B are schematic block diagrams of the closed-loop coagulation control in accordance with the present invention.

Detailed description

In the following, particular embodiments of the present invention will be described with reference to the accompanying drawings. In the description that follows, well-known functions and constructions are not described in detail in order to avoid complicating the present disclosure with unnecessary detail.

The present invention provides an electrosurgical system with precision closed-loop monitoring of tissue and energy properties. The system includes a generator that is configured as a high-speed radio frequency (RF) power source. The control circuit includes a plurality of sensors to sense energy and tissue properties and a gain control to modify the output of the generator. Sensors monitor tissue properties in real time to allow a built-in controller to provide corrective adjustment of delivered RF energy. The closed loop control automatically corrects the applied RF energy, based on energy and tissue properties, according to a prescribed algorithm, determined by clinical procedure. The generator receives the corrective setting from the controller and dynamically modifies the delivered energy in direct response to changes in tissue properties, until a desired clinical effect is achieved.

Fig. 1 is a schematic illustration of an electrosurgical system 1 configured for a monopolar procedure. System 1 includes an active electrode 14 and a return electrode 16 for treating tissue from a patient P. Electrosurgical RF energy is fed to the active electrode 14 by a generator 10 through a lead 18, allowing the active electrode 14 destroy, cut, or coagulate tissue. Return electrode 16 is arranged on patient P to return energy from patient P to generator 10 through lead 19.

ES 2 327 005 T3

Generator 10 includes input controls (eg, pushbuttons, triggers, switches, etc.) to control generator 10. The controls allow the surgeon to regulate the RF energy power, waveform, and other parameters, to in order to achieve the desired waveform, suitable for a particular task (for example, cutting, coagulating, etc.). Disposed between the generator 10 and the active electrode 14 on the lead 18, is a handle piece 21, which includes a plurality of input controls that can be redundant with certain input controls of the generator 10. Placing the input controls on The handle piece 12 allows for an easier and faster modification of the RF energy parameters during the surgical procedure, without returning to the generator 10. It is also contemplated that a foot switch may be connected to generator 10 to control power delivery during monopolar procedures. It is further contemplated that the handle piece 12 and electrode 14 may be incorporated into a single instrument, for example a surgical pencil, with the electrode 14 being disposed at the distal end of the handle piece 12.

Fig. 2 shows a schematic block diagram of generator 10 having a microprocessor 22, a high voltage direct current power supply ("HVPS") 28, an RF output stage 30, at least one RF sensor 32 configured to measuring one or more tissue and / or energy properties, and a gain controller 34. The microprocessor 22 includes a controller 26 and an output port that is electrically connected to the HVPS 28 configured to feed a direct current voltage, from about 0 V to about 2000 V to the RF output stage 30. The microprocessor 22 receives input signals from the generator 10, the handle piece 12 or the foot switch and the controller 26 and, in turn, adjusts the output parameters of the generator 10, more specifically the HVPS 28 and / or performs other control functions over it. It is also contemplated that the controller 26 is configured to receive control signals from the gain controller 34 to dynamically regulate the RF energy that is being delivered to the tissue.

The RF output stage 30 converts direct current power into RF energy and delivers the RF energy, at about 470 kHz, to the active electrode 14 or other electrosurgical devices connected to the generator 10. In addition, the RF output stage 30 RF also receives RF energy from return electrode 16. RF sensor 32 is connected to the input and output (e.g., connections to active electrode 14 and return electrode 16) of RF output stage 30 to sense tissue and energy properties (e.g. , impedance, voltage, current, temperature, phase, voltage peaks, crest factor, current peaks, real and reactive power, voltage regime change with time [dv / dt], phase regime change with time [d ^ / dt], change of current regime with time [dI / dt], change of temperature regime with time [dT / dt], change of impedance regime with time [dz / dt], higher order harmonics of the 472 kHz fundamental wave, etc.).

Generator 10 includes a closed-loop control system 50 having microprocessor 22, controller 26, RF sensor 32, and gain controller 34 along with components thereof shown in FIGS. 3A-B and described in more detail below. RF sensor 32 transmits signals representing energy and / or tissue properties through gain control 34 to adjust the RF energy output accordingly. The perceived properties are transmitted to the microprocessor 22 and the controller 26 to perform calculations to determine the adjustments to be made to the RF energy output. Microprocessor 22 compares impedance, voltage, and other measurements with desired values ​​and sends signals to RF output stage 30 to make any adjustments necessary to achieve the desired values.

In addition to impedance and voltage, the microprocessor 22 also measures the voltage at a peak of the waveform (Vpk) and the effective voltage (Vrms). Calculations of the peak and rms values ​​are also performed using the intensity value (I). To calculate the RMS values, the sampling rates of the voltage and current signals must correspond to the size of the sensor buffer 32. More specifically, the microprocessor 22 includes a buffer dimensioned to contain an integer number of complete cycles of the waveform at a specific sampling rate to avoid modulation errors within the RMS values. This allows sensor 32 to prepare data acquisition for the various waveforms associated with RF coagulation energy.

The microprocessor 22 calculates the crest factor (Vpk / Vrms or Ipk / Irms) and the peak values ​​of V and I in real time and controls the timing of the output waveform and the RF amplitude as a function of the themselves. It is contemplated that the real-time calculation of the crest factor can be used to adjust the RF energy or adjust the waveform to maintain a crest factor profile. More specifically, the real-time calculation of the crest factor allows the coagulation modes to be controlled by regulating the RF energy output to maintain a predetermined crest factor. The crest factor or peak values ​​of V and I can be kept constant and the timing of the output waveform and RF amplitude adjusted accordingly.

Gain controller 34 processes the perceived intensity and voltage signals received from RF sensor 32. More specifically, the gain controller 34 reduces the high amplitudes of the coagulation intensity and voltage signals, allowing the signals to be transmitted to the microprocessor 22 for processing. Gain control 34 provides both amplification and attenuation of voltage and current signals to obtain good signal-to-noise ratios to minimize binary quantization error. The resolution and precision of the perceived RF allows precise control of the energy dosage to the patient.

ES 2 327 005 T3

With reference to figs. 3A-B, the gain control process is illustrated by two embodiments. Fig. 3A shows the gain controller 34, which includes the RF sensor voltage scaling control 35 and a gain control 37 connected to an analog multiplier 36 which is then connected to an anti-overlap filter 38. In this embodiment , the gain controller 34 adjusts the perceived voltage of the RF energy. The scaling control 35 receives RF signals (eg, signals representative of the RF energy being outputted by the generator 10) from the RF sensor 32 and dynamically and automatically scales the RF signal. to adjust the high amplitude values ​​of the RF intensity and voltage signals for coagulation. The gain control 37 provides the real-time gain modification of the RF energy by treating a variable control signal of the DC value received from the controller 26. The analog multiplier 36 performs a real-time multiplication of the inputs of Signal received from the outputs of voltage scaling control 35 and gain control 37. The analog multiplier 36 normalizes the RF sensor signals independent of the high amplitude values ​​of the RF output 30 to achieve maximum precision of the delivered RF energy.

Anti-overlap filter 38 blocks the fundamental RF frequency and harmonics preventing them from contributing errors to the computational processing performed by controller 26. Filter 38 treats RF energy to reduce RF noise components and increase accuracy of RF energy delivered to the patient. It is also contemplated that the RF sensor 32 also includes an amplitude reduction circuit (not shown) to protect the front end of the multiplier 44.

Fig. 3B shows another embodiment of gain controller 34 that includes RF sensor intensity scaling control 39. In this embodiment, the gain controller 34 adjusts the perceived intensity of the RF energy. Gain control 37 is connected to analog multiplier 36 and anti-overlap components, similar to that depicted in FIG. 3A and described above. The output of the anti-overlap filter 38 is fed to the output line (eg, leading to the controller 26). In fig. 3B, the output of the analog multiplier 36 is matched in intensity 1: 1 with the intensity input of the RF sensor received from the RF sensor 32. The adder 40 processes the difference signals between the analog multiplier 36 and the intensity input of the RF sensor in conjunction with an operational amplifier ("OPamp") to create an equivalent, normalized RF output signal independent of the values ​​of high amplitude of the RF output stage 30. The input limiter 42 provides impulse protection for the input of the op amp 44 to increase the reliability of the gain controller 34.

The generator 10 is capable of making small adjustments to the high resolution RF waveform (eg, 10 ns). This allows the crest factor and peak outputs to be controlled, as well as tuning the waveforms so that the output frequency can be adjusted to match the resonant frequency of the RF output stage 30. The generator 10 is configured to model the output curves to one degree using a linear interpolation method that allows any described curve within a predetermined number of points (eg, 15), when the curves represent current, power, voltage, etc. .

The embodiments described in the present disclosure are intended to be illustrative and not restrictive and are not intended to represent all embodiments of the present invention. Various modifications and variations may be made without departing from the scope of the invention as set forth in the following claims.