# US 2014/0155880 A1 · Method and system for adjusting source impedance and maximizing output by rf generator

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- Number: US 2014/0155880 A1
- Document ID: US20140155880A1
- Status: Published application
- Kind: A1
- Application number: 14/156,551
- Filed: 2014-01-16
- Published: 2014-06-05
- Earliest claimed: 2009-03-17
- Assignees: Stryker Corporation
- Inventors: Steffan A. BENAMOU; Andrew J. HAMEL; David HOFFMAN; David I. BRUBAKER
- Web page: https://patentgrep.com/patent/US20140155880A1

## CPC

- A61B 18/1206: {Generators therefor}
- A61B 18/1233: {with circuits for assuring patient safety}
- A61B 18/148: {having a short, rigid shaft for accessing the inner body transcutaneously, e.g. for neurosurgery or arthroscopy}
- A61B 18/18: by applying electromagnetic radiation, e.g. microwaves
- A61B 2017/00477: {Coupling (A61B2017/0046 takes precedence)}
- A61B 2017/00973: {pedal-operated}
- A61B 2018/00589: {Coagulation}
- A61B 2018/00601: {Cutting}
- A61B 2018/00607: {Coagulation and cutting with the same instrument}
- A61B 2018/00702: {Power or energy}
- A61B 2018/00755: {Resistance or impedance}
- A61B 2018/00767: {Voltage}
- A61B 2018/00779: {Power or energy}
- A61B 2018/00988: {Means for storing information, e.g. calibration constants, or for preventing excessive use, e.g. usage, service life counter}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

An electrosurgical system includes an electrosurgical probe connected to a control console, wherein the probe is capable of coagulating and ablating tissue depending on a selected operating mode. Before operating the system, probe-specific data stored in a memory device associated with the probe is read by a processing device in the console. The data includes source impedance values specific to a coagulation or cutting mode of operation. A constant duty cycle value for a modulated cutting mode also is provided. Depending on the operating mode selected, an RF generator adjusted to have a predetermined source impedance value provides a voltage value to the probe. During the duty-cycled mode, the RF generator generates an instantaneous voltage value output for a duty cycle portion that is less than 100% of a time period, which value is no less than a maximum continuous average voltage value for the electrosurgical probe.

## Claims

### Claim 1

Method of controlling source impedance of an RF generator in a control console for an electrosurgical system including an electrosurgical RF probe, the control console being in communication with a memory device associated with the RF probe, the method comprising the steps of:
connecting the electrosurgical RF probe to the control console having the RF generator, the memory device associated with the RF probe providing probe-specific data stored in the memory device to a processing device in the control console, the probe data comprising at least a first source impedance value corresponding to a coagulation operating mode for the RF probe and a second source impedance value corresponding to a cutting operating mode for the RF probe;
selecting the coagulation operating mode or the cutting operating mode, the processing device operating so that the source impedance of the RF generator has a source impedance value corresponding to the first source impedance value when the coagulation operating mode is selected by an operator and so that the source impedance of the RF generator has the second source impedance value when the cutting operating mode is selected by an operator; and
operating the RF probe to coagulate or cut tissue at a surgical site.

### Claim 2 (depends on 1)

The method of claim 1, wherein the RF probe comprises a first RF probe, and wherein at least one of the first and second source impedance values stored in the memory device associated with the first RF probe is different from at least one of corresponding first and second source impedance values stored in a memory device associated with a second RF probe.

### Claim 3 (depends on 1)

The method of claim 1, wherein the probe-specific data provided to the processing device comprises a maximum voltage average value and a constant duty cycle value for the RF probe.

### Claim 4 (depends on 1)

The method of claim 1, wherein the first source impedance value is different than the second source impedance value.

### Claim 5

Method of controlling a cutting operation for an electrosurgical cutting system including a control console, an RF generator, and an electrosurgical RF probe, the method comprising the steps of:
connecting the RF probe associated with a memory device to the control console to provide probe-specific data stored in the memory device to a processing device in the control console, the probe data comprising a maximum continuous average voltage value and a constant duty cycle value of less than 100% and corresponding proportionally to a time period defined by a secondary frequency value, the processing device having a maximum instantaneous voltage value based on the probe data; and
actuating the RF generator to output an instantaneous voltage value in a range that is not less than approximately the maximum average voltage value and that is not greater than approximately the maximum instantaneous voltage value to the RF probe to cut tissue during the constant duty cycle value which comprises a first portion of the time period, and wherein no voltage value is output by the RF generator or applied to the RF probe during a second remaining portion of each said time period.

### Claim 6 (depends on 5)

The method of claim 5, wherein the step of actuating the RF generator includes selecting application of the continuous average voltage value having no duty cycle to the RF probe.

### Claim 7 (depends on 5)

The method of claim 5, wherein the RF probe comprises a first RF probe with a first constant duty cycle value and a second electrosurgical RF probe different from the first RF probe is provided having a second constant duty cycle value that is different from the first duty cycle value of the first probe.

### Claim 8

Method of controlling the operation of an RF generator disposed in a control console of an electrosurgical system including an electrosurgical RF probe having a memory device, the method comprising the steps of:
connecting the electrosurgical RE probe having the memory device to the control console, a processing device disposed in the control console for receiving probe-specific data stored in the memory device, the probe-specific data comprising a constant continuous coagulation voltage value, maximum continuous average voltage value and a constant cutting duty cycle value for operating the probe in a cutting operating mode, the processing device provided with a maximum instantaneous voltage value related to the maximum continuous average voltage value and a constant duty cycle value;
selecting a coagulation operating mode or the cutting operating mode, wherein in the cutting operating mode the operator selects a continuous cutting mode or a modulated cutting mode, wherein in the modulated cutting mode the RE generator intermittently outputs to the RF probe an instantaneous voltage value that is no less than the maximum continuous average voltage value and no more than the maximum instantaneous voltage value, the constant cutting duty cycle value being defined as a percent value that is less than 100%, and wherein the instantaneous voltage value is applied to the probe during the constant cutting duty cycle value of a time period that is defined by the inverse of a first secondary frequency value, the intermittent application of the instantaneous voltage value enabling cutting of tissue, and wherein in the coagulation operating mode the RF generator outputs the constant continuous coagulation voltage value for obtaining a desired coagulation effect; and
operating the electrosurgical system to coagulate or cut tissue at a surgical site.

### Claim 9 (depends on 8)

The method of claim 8, wherein the probe specific data further comprises a constant coagulation duty cycle value for a period defined by the inverse of a second secondary frequency value, that is provided to the processing device for operating the RF generator in a modulated coagulation mode.

### Claim 10 (depends on 9)

The method of claim 9, wherein connecting the RF probe to the control console comprises connecting a cable of the RF probe to a single RF cable port on the control console to supply power to the RF probe.

### Claim 11 (depends on 9)

The method of claim 9, wherein the first secondary frequency value and the second secondary frequency value are equal and are stored in the processing device, and wherein the cutting duty cycle value is different than the coagulation duty cycle value.

### Claim 12 (depends on 8)

The method of claim 8, wherein the probe-specific data further comprises the maximum instantaneous voltage value, a coagulation source impedance value for the RF generator in the coagulation operating mode and the probe-specific data further comprises a cutting source impedance value for the RF generator in the cutting operating mode.

### Claim 13 (depends on 12)

The method of claim 12, wherein the step of selecting the coagulation operating mode or the cutting operating mode comprises providing the RF generator with the coagulation source impedance value from the processing device in the control console when the coagulation operating mode is selected by an operator, and providing the RF generator with the cutting source impedance value from the processing device in the control console when the cutting operating mode is selected by an operator, the coagulation source impedance value being different than the cutting source impedance value.

### Claim 14

An electrosurgical system, comprising:
a control console having a processing device disposed therein;
an electrosurgical probe that detachably connects to the control console;
an RF generator for generating a voltage value for energizing the electrosurgical probe; and
a memory device associated with the RF probe, the memory device storing probe-specific operating parameters including a cutting duty cycle value for a cutting mode,
wherein the processing device obtains the probe-specific parameters from the memory device and after selection of the cutting mode, the processing device controls the RF generator to output an instantaneous voltage value for the constant cutting duty cycle portion of each time period defined by the inverse of a secondary frequency, wherein the instantaneous voltage value is intentionally greater than a maximum average voltage value.

### Claim 15 (depends on 14)

The electrosurgical system of claim 14, wherein the instantaneous voltage value is more than the maximum average voltage value/cutting duty cycle value, whereby the instantaneous voltage value applied to the RF probe exceeds the maximum average voltage value.

### Claim 16 (depends on 14)

The electrosurgical system of claim 14, wherein the secondary frequency value is stored in the processing device.

### Claim 17 (depends on 14)

The electrosurgical system of claim 14, wherein the probe-specific operating parameters stored in the memory device include a coagulation duty cycle value for a modulated coagulation mode, the parameters being obtained by the processing device so that in operation, after selection of the coagulation mode having a coagulation duty cycle value instead of no duty cycle, the processing device controls the RF generator to output an instantaneous coagulation voltage value for a constant coagulation duty cycle portion that is less than 100% of each time period defined by the inverse of the secondary frequency.

### Claim 18 (depends on 17)

The electrosurgical system of claim 17, wherein the probe-specific operating parameters stored in the memory device comprise source impedance values including a first source impedance value for the RF generator in the coagulation mode and a second source impedance value for the RF generator in the cutting mode.

### Claim 19 (depends on 14)

The electrosurgical system of claim 14, wherein the probe-specific operating parameters stored in the memory device comprise a first source impedance value for the RF generator in a coagulation mode and a second source impedance value for the RF generator in the cutting mode.

### Claim 20 (depends on 19)

The electrosurgical system according to claim 19, wherein the first source impedance value is different than the second source impedance value.