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

Patent metadata

Field	Value
Publication number	US-9289254-B2
Application number	US-200913126846-A
Country	US
Kind code	B2
Filing date	Oct 28, 2009
Priority date	Oct 30, 2008
Publication date	Mar 22, 2016
Grant date	Mar 22, 2016

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.

First claim

The invention claimed is:

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:

Δ
⁢

⁢
T

=

R
⁡

(
T
)

-

R
⁡

(

T
0

)

α
*

R
⁡

(

T
0

)

wherein:
α is a specific temperature coefficient,
T 0 is a starting temperature,
R(T 0 ) is an impedance at the starting temperature T 0 ,
R(T) is the measured impedance.

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 lim

Assignees

• Selig Peter
• Erbe Elektromedizin

Inventors

• Selig Peter

Classifications

• A61B2018/00797

  measured by multiple temperature sensors · CPC title

• A61B2018/00791

  Temperature · CPC title

• A61B18/1206 Primary

  Generators therefor · CPC title

• A61B5/053

  Measuring electrical impedance or conductance of a portion of the body · CPC title

• A61B2018/00875

  Resistance or impedance · CPC title