System and method for measuring initial tissue impedance

• US 20080039831A1
• Filed: 08/08/2006
• Published: 02/14/2008
• Est. Priority Date: 08/08/2006
• Status: Active Grant

• Current Assignee: Covidien AG (Medtronic Plc)
• Original Assignee: Sherwood Services AG
• Inventors: Weinberg, Craig, Denham, Amy, Odom, Darren
• Granted Patent: US 8,034,049 B2
• Time in Patent Office: Days
• US Class Current: 606/34
• CPC Class Codes: A61B 18/1445 at the distal end of a shaft, e.g. forceps or scissors at the end of a rigid rod
• CPC Class Codes: A61B 2018/0063 Sealing
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00875 Resistance or impedance

Abstract

An electrosurgical system and method are disclosed. The system includes an electrosurgical generator adapted to supply electrosurgical energy to tissue. The generator is further adapted to supply an electrical signal having at least one substantially constant value to tissue to determine initial tissue impedance response. The generator includes sensor circuitry adapted to continuously monitor initial tissue impedance response, wherein the initial tissue impedance response includes one of an initial impedance, an impedance drop, an impedance minimum and a first impedance rise. The generator also includes a microprocessor adapted to generate at least one tissue parameter based as a function of the initial impedance, the impedance drop, the impedance minimum and the first impedance rise. The system also includes an electrosurgical instrument including at least one active electrode adapted to apply electrosurgical energy to tissue for treatment.

Claims

1. An electrosurgical system comprising:

an electrosurgical generator adapted to supply electrosurgical energy to tissue, the generator further adapted to supply an electrical signal having at least one substantially constant value to tissue to determine initial tissue impedance response, the generator including;

sensor circuitry adapted to continuously monitor initial tissue impedance response, wherein the initial tissue impedance response includes an initial impedance, an impedance drop, an impedance minimum and a first impedance rise; and

a microprocessor adapted to generate at least one tissue treatment parameter as a function of the at least one initial impedance, the impedance drop, the impedance minimum and the first impedance rise; and

an electrosurgical instrument including at least one active electrode adapted to apply electrosurgical energy to tissue for treatment.

2. An electrosurgical system as in claim 1, wherein the microprocessor is further adapted to adjust output of the electrosurgical generator based on the at least one tissue parameter.

3. An electrosurgical system as in claim 1, wherein the at least one tissue parameter is selected from the group consisting of pressure to be applied to tissue, duration of energy application, amount of energy to be supplied and target impedance trajectory.

4. An electrosurgical system as in claim 1, wherein the electrosurgical instrument is an electrosurgical forceps for sealing tissue, the forceps comprising:

at least one shaft member having an end effector assembly disposed at a distal end thereof, the end effector assembly including jaw members movable from a first position in spaced relation relative to one another to at least one subsequent position wherein the jaw members cooperate to grasp tissue therebetween; and

a sealing plate attached to each of the jaw members in apposing relation thereto, said sealing plates adapted to connect to the electrosurgical generator such that said sealing plates communicate electrosurgical energy through tissue held therebetween.

5. An electrosurgical system as in claim 1, wherein the constant value of the electrical signal is selected from the group consisting of constant voltage, constant current, constant power and constant energy.

6. A method for performing electrosurgical procedures:

supplying an electrical signal having at least one substantially constant value to tissue to determine an initial tissue impedance response, said initial tissue response including at least one of an initial impedance, an impedance drop, an impedance minimum and a first impedance rise

continuously monitoring said initial tissue impedance response; and

generating at least one tissue treatment parameter as a function of at least one of the initial impedance, the impedance drop, the impedance minimum and the first impedance rise.

7. A method as in claim 6, further comprising the step of:

adjusting the output of the electrosurgical generator based on the at least one tissue parameter.

8. A method as in claim 7, wherein the at least one tissue parameter is selected from the group consisting of pressure to be applied to tissue, duration of energy application, amount of energy to be supplied and target impedance trajectory.

9. A method as in claim 6, further comprising the step of:

1

providing an electrosurgical instrument including at least one active electrode adapted to apply electrosurgical energy to tissue.

10. A method as in claim 9, wherein the step of providing an electrosurgical instrument further includes providing an electrosurgical forceps for sealing tissue, the forceps comprising:

at least one shaft member having an end effector assembly disposed at a distal end thereof, the end effector assembly including jaw members movable from a first position in spaced relation relative to one another to at least one subsequent position wherein the jaw members cooperate to grasp tissue therebetween; and

a sealing plate attached to each of the jaw members in apposing relation thereto, said sealing plates adapted to connect to the electrosurgical generator such that said sealing plates communicate electrosurgical energy through tissue held therebetween.

11. A method as in claim 6, wherein the constant value of the electrical signal is selected from the group consisting of constant voltage, constant current, constant power and constant energy.

12. An electrosurgical generator adapted to supply electrosurgical energy to tissue comprising:

an RF output stage adapted to supply electrosurgical energy to tissue and further adapted to supply an electrical signal having at least one substantially constant value to tissue to determine an initial tissue impedance response;

sensor circuitry adapted to continuously monitor initial tissue impedance response, wherein the initial tissue impedance response includes at least one of an initial impedance, an impedance drop, an impedance minimum and a first impedance rise; and

a microprocessor adapted to generate at least one tissue treatment parameter as a function of at least one of the initial impedance, the impedance drop, the impedance minimum and the first impedance rise.

13. An electrosurgical generator as in claim 12, wherein the microprocessor is further adapted to adjust output of the electrosurgical generator based on the at least one tissue parameter.

14. An electrosurgical generator as in claim 12, wherein the at least one tissue parameter is selected from the group consisting of pressure to be applied to tissue, duration of energy application, amount of energy to be supplied and target impedance trajectory.

15. An electrosurgical generator as in claim 12, wherein the electrosurgical generator is connected an electrosurgical instrument including at least one active electrode adapted to apply electrosurgical energy to tissue.

16. An electrosurgical generator as in claim 15, wherein the electrosurgical instrument is an electrosurgical forceps for sealing tissue, the forceps comprising:

at least one shaft member having an end effector assembly disposed at a distal end thereof, the end effector assembly including jaw members movable from a first position in spaced relation relative to one another to at least one subsequent position wherein the jaw members cooperate to grasp tissue therebetween; and

a sealing plate attached to each of the jaw members in apposing relation thereto, said sealing plates adapted to connect to the electrosurgical generator such that said sealing plates communicate electrosurgical energy through tissue held therebetween.

17. An electrosurgical generator as in claim 12, wherein the constant value of the electrical signal is selected from the group consisting of constant voltage, constant current, constant power and constant energy.