Imaginary Impedance Process Monitoring and Intelligent Shut-Off

• US 20100179538A1
• Filed: 06/03/2009
• Published: 07/15/2010
• Est. Priority Date: 01/12/2009
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Tyco Healthcare Group LP (Medtronic Plc)
• Inventors: Podhajsky, Ronald J.
• Granted Patent: US 8,262,652 B2
• Time in Patent Office: Days
• US Class Current: 606/35
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/1442 Probes having pivoting end effectors, e.g. forceps
• CPC Class Codes: A61B 2018/00678 upper
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00875 Resistance or impedance

Abstract

An electrosurgical generator for supplying electrosurgical energy to tissue is disclosed. The generator includes sensor circuitry configured to measure an imaginary impedance and/or a rate of change of the imaginary impedance of tissue. The generator also includes a controller configured to regulate output of the electrosurgical generator based on the measured imaginary impedance and/or the rate of change of the imaginary impedance.

Claims

1. An electrosurgical generator for supplying electrosurgical energy to tissue, comprising:

sensor circuitry configured to measure at least one of an imaginary impedance and a rate of change of the imaginary impedance of tissue; and

a controller configured to regulate output of the electrosurgical generator based on the at least one of the imaginary impedance and the rate of change of the imaginary impedance.

2. The electrosurgical generator according to claim 1, wherein the controller includes:

a microprocessor configured to execute at least two recursive filters configured to recursively process the imaginary impedance.

3. The electrosurgical generator according to claim 2, wherein the microprocessor is configured to preload the at least two recursive filters with an initial value of the imaginary impedance.

4. The electrosurgical generator according to claim 1, wherein the controller is configured to regulate the electrosurgical generator based on a rate of change of the imaginary impedance and is configured to control the generator to continue application of the electrosurgical energy when the rate of change of the imaginary impedance is above a first predetermined threshold.

5. The electrosurgical generator according to claim 4, wherein the controller is configured to regulate the electrosurgical generator to discontinue application of the electrosurgical energy when the rate of change of the imaginary impedance is below a second predetermined threshold.

6. The electrosurgical generator according to claim 5, wherein the controller is configured to regulate the electrosurgical generator to commence intelligent shut-off of the electrosurgical energy for a duration of a predetermined time delay when the rate of change of the imaginary impedance is between the first and second predetermined thresholds.

7. The electrosurgical generator according to claim 6, wherein the controller is configured to regulate the electrosurgical generator to restart application of the electrosurgical energy when the rate of change of the imaginary impedance is above the first predetermined threshold during the time delay.

8. A method for supplying electrosurgical energy to tissue, comprising the steps of:

measuring at least one of an imaginary impedance and a rate of change of the imaginary impedance of tissue; and

regulating output of the electrosurgical generator based on the at least one of the imaginary impedance and rate of change of the imaginary impedance.

9. The method according to claim 8, further comprising the step of:

recursively processing the imaginary impedance to obtain an averaged value of the imaginary impedance.

10. The method according to claim 9, wherein the recursively processing step further includes the step of preloading the at least two recursive filters with an initial value of the imaginary impedance.

11. The method according to claim 8, wherein the method further includes a step of measuring a rate of change of the imaginary impedance of tissue and the regulating step further includes the step of continuing application of the electrosurgical energy when the rate of change of the imaginary impedance is above a first predetermined threshold.

12. The method according to claim 11, wherein the regulating step further includes the step of:

discontinuing application of the electrosurgical energy when the rate of change of the imaginary impedance is below a second predetermined threshold.

13. The method according to claim 11, wherein the regulating step further includes comprising the step of:

commencing intelligent shut-off of the electrosurgical energy for a duration of predetermined time delay when the rate of change of the imaginary impedance is between the first and second predetermined thresholds.

14. The method according to claim 12, wherein the regulating step further includes the step of:

restarting application of the electrosurgical energy when the rate of change of the imaginary impedance is above the first predetermined threshold during the time delay.

15. A method for supplying electrosurgical energy to tissue, comprising the steps of:

measuring an imaginary impedance and a rate of change of the imaginary impedance of tissue; and

regulating output of the electrosurgical generator based on at least one of the imaginary impedance and rate of change of the imaginary impedance, wherein the regulating step further includes the step of;

comparing the rate of change of the imaginary impedance with a first predetermined threshold and a second predetermined threshold.

16. The method according to claim 15, further comprising the step of:

recursively processing the imaginary impedance to obtain an averaged value of the imaginary impedance.

17. The method according to claim 16, wherein the recursively processing step further includes a step of preloading the at least two recursive filters with an initial value of the imaginary impedance.

18. The method according to claim 15, wherein the regulating step further includes the step of:

continuing application of the electrosurgical energy when the rate of change of the imaginary impedance is above a first predetermined threshold.

19. The method according to claim 15, wherein the regulating step further includes the step of:

discontinuing application of the electrosurgical energy when the rate of change of the imaginary impedance is below a second predetermined threshold.

20. The method according to claim 15, wherein the regulating step further includes the steps of:

commencing intelligent shut-off of the electrosurgical energy for a duration of a predetermined time delay when the rate of change of the imaginary impedance is between the first and second predetermined thresholds; and

restarting application of the electrosurgical energy when the rate of change of the imaginary impedance is above the first predetermined threshold during the time delay.