Electrosurgical device having a temperature measurement device, method for determining a temperature and/or a temperature change at a neutral electrode

• US 9,289,254 B2
• Filed: 10/28/2009
• Issued: 03/22/2016
• Est. Priority Date: 10/30/2008
• Status: Active Grant

• Current Assignee: Erbe Elektromedizin GmbH (C. Erbe GmbH)
• Original Assignee: Erbe Elektromedizin GmbH (C. Erbe GmbH)
• Inventors: Selig, Peter
• Primary Examiner(s): Peffley, Michael
• Application Number:
  US13/126,846
• Publication Number:
  US 20110202055A1
• Time in Patent Office: 2,337 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/1233 with circuits for assuring patient safety
• CPC Class Codes: A61B 18/16 Indifferent or passive electrodes for grounding
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2018/00797 measured by multiple temperature sensors
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2562/08 Sensors provided with means for identification, e.g. barcodes or memory chips
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body

Abstract

A method for determining a temperature and/or a temperature change at a neutral electrode having a contacting agent layer. The method comprises determining at least one impedance value of the contacting agent layer and calculating a temperature change and/or a temperature at the neutral electrode, at least on the basis of the impedance value. The contacting agent layers may be made from hydrogel and the method uses a correlation that exists between the temperature change and the impedance change.

Claims

1. An electrosurgical device, comprising:

a high frequency (HF) generator for generating an HF current, which can be conducted into a biological tissue via an instrument; and

a neutral electrode having a contacting agent layer, wherein the contacting agent layer has material properties such that the impedance thereof decreases with increasing temperature,

wherein the HF generator comprises a temperature measurement device for determining a temperature and/or a temperature change at the neutral electrode, the temperature measurement device comprising;

an impedance measurement device, for determining the temperature and/or the temperature change, configured to detect an impedance of the contacting agent layer, the impedance measurement device comprises a measurement current generator, configured to provide a measurement current to a first electrode section and a second electrode section,

wherein the temperature measurement device comprises a device configured to sum up impedance change values over a time period to make a thermal balance estimation, and

wherein the time period comprises a plurality of activation and deactivation phases of the HF generator.

2. The electrosurgical device of claim 1, wherein the measurement current generator is configured to provide the measurement current with an alternating voltage having a frequency less than or equal to 300 kHz.

3. The electrosurgical device of claim 2, wherein the frequency is less than or equal to 150 kHz.

4. The electrosurgical device of claim 2, wherein the frequency is less than or equal to 100 kHz.

5. The electrosurgical device of claim 1, wherein the electrode sections are arranged electrically insulated from one another on the contacting agent layer.

6. The electrosurgical device of claim 1, wherein the HF generator is configured to provide an HF current with an alternating voltage at a frequency greater than or equal to 300 kHz.

7. The electrosurgical device of claim 6, wherein the HF generator is configured to provide an HF current with an alternating voltage at a frequency greater than or equal to 1000 kHz.

8. The electrosurgical device of claim 1, wherein the contacting agent layer has an electrical impedance having a temperature dependence having a relative impedance change of greater than or equal to 1% per degree Celsius.

9. The electrosurgical device of claim 8, wherein the contacting agent layer has an electrical impedance having a temperature dependence having a relative impedance change of greater than or equal to 2% per degree Celsius.

10. The electrosurgical device of claim 1, wherein the contacting agent layer comprises hydrogel.

11. The electrosurgical device of claim 1, wherein the temperature measurement device comprises an impedance integration device configured to integrate impedance changes over a pre-determined time period to make a thermal balance estimation.

12. The electrosurgical device of claim 1, further comprising a recognition device for determining parameters of at least one electrode area of the neutral electrode and/or of a temperature coefficient.

13. The electrosurgical device of claim 12, wherein the recognition device comprises a database with a plurality of parameters and a plurality of neutral electrode types and the recognition device is configured to detect the connection of a particular neutral electrode type and to read out the parameters from the database.

14. The electrosurgical device of claim 1, further comprising an interruption device configured to interrupt or limit the HF current on exceeding a pre-determined impedance change.

15. The electrosurgical device of claim 1, wherein the temperature measurement device accounts for the effective value of the HF current to determine the temperature and/or the temperature change.

16. The electrosurgical device of claim 1, further comprising:

a current integration device, configured to total up a value relating to the HF current over time, and to put said value in relation to an impedance change to determine the temperature and/or the temperature change.

17. The electrosurgical device of claim 16, wherein the current integration device is configured to total up the effective value of the HF current over time.

18. A method for determining a temperature and/or a temperature change at a neutral electrode having a contacting agent layer, wherein the contacting agent layer has material properties such that the impedance thereof decreases with increasing temperature, the method comprising:

determining a plurality of impedance values of the contacting agent layer, thereby detecting at least a first impedance change value during an activation phase and at least a second impedance change value during a deactivation phase; and

calculating a temperature change and/or a temperature at the neutral electrode at least on the basis of the determined impedance change values.

19. The method of claim 18, wherein the determining step takes place at a plurality of times during a plurality of activation and deactivation phases to determine a plurality of impedance values.

20. The method of claim 19, wherein the calculating step accounts for the duration of the activation and/or deactivation phases.

21. The method of claim 19, wherein the calculating step comprises integrating a plurality of impedance values over time.

22. The method of claim 18, wherein the calculating step comprises calculating at least one quotient between impedance change and activation time or deactivation time.

23. The method of claim 22, wherein the calculating of the temperature change comprises a linear estimation using the formula:

24. The method of claim 23, further comprising:

detecting a particular type of connected neutral electrode; and

selecting a pre-determined temperature coefficient depending on the detected neutral electrode type.

25. The method of claim 18, further comprising outputting of a warning signal if a measured impedance change exceeds a pre-determined limit value.

26. The method of claim 18, further comprising switching off the HF current if a measured impedance change exceeds a pre-determined limit value.

27. The method of claim 18, further comprising reducing the HF current if a measured impedance change exceeds a pre-determined limit value.

28. A method for determining a temperature and/or a temperature change at a neutral electrode having a contacting agent layer, wherein the contacting agent layer has material properties such that the impedance thereof decreases with increasing temperature, the method comprising:

detecting a particular type of connected neutral electrode;

selecting a pre-determined temperature coefficient depending on the neutral electrode types;

determining a plurality of impedance value of the contacting agent layer to determine impedance change values; and

calculating a temperature change and/or a temperature at the neutral electrode at least on the basis of the impedance change values and the selected pre-determined temperature coefficient.