Vessel sealing system

• US 20030004510A1
• Filed: 02/11/2002
• Published: 01/02/2003
• Est. Priority Date: 09/30/1999
• Status: Active Grant

• Current Assignee: Covidien AG (Medtronic Plc)
• Original Assignee: Sherwood Services AG
• Inventors: Buysse, Steven P., Orszulak, James H., Wham, Robert
• Granted Patent: US 6,796,981 B2
• Time in Patent Office: Days
• US Class Current: 606/51
• CPC Class Codes: A61B 18/1442 Probes having pivoting end effectors, e.g. forceps
• 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 2017/2945 Curved jaws
• CPC Class Codes: A61B 2018/00404 Blood vessels other than those in or around the heart
• CPC Class Codes: A61B 2018/00601 Cutting
• CPC Class Codes: A61B 2018/0063 Sealing
• CPC Class Codes: A61B 2018/00726 Duty cycle
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/1432 curved

Abstract

A method for electrosurgically sealing a tissue includes steps of: (A) applying a first pulse of RF energy to the tissue; and (B) applying at least one subsequent RF energy pulse to the tissue and varying RF energy parameters of individual pulses of subsequent RF energy pulses in accordance with at least one characteristic of an electrical transient that occurs during the individual pulses of the subsequent RF energy pulses. The method terminates the generation of subsequent RF pulses upon a determination that the electrical transient has passed a predetermined limit.

Claims

1. A method for electrosurgically sealing tissue, comprising the steps of:

applying a first pulse of RF energy to the tissue; and

applying at least one subsequent RF energy pulse to the tissue and varying RF energy parameters of individual pulses of subsequent RF energy pulses in accordance with at least one characteristic of an electrical transient that occurs during the individual pulses of the subsequent RF energy pulses.

2. A method as in claim 1, wherein the step of applying the first pulse includes a step of selecting characteristics of the first pulse so as not to appreciably heat the tissue.

3. A method as in claim 1, wherein the step of applying the first pulse comprises the steps of:

continuously measuring at least one characteristic of a response of the tissue to the applied first pulse; and

in accordance with the measured characteristic, determining whether to change a set of RF energy parameters to a default set of RF energy parameters.

4. A method as in claim 3, wherein the default set of RF energy parameters comprise a magnitude of a starting power and a magnitude of a starting voltage.

5. A method as in claim 1, wherein the electrical transient is an electric current transient.

6. A method as in claim 5, wherein the at least one characteristic of said electrical transient is a rate of change of the electric current transient.

7. A method as in claim 1, wherein the electrical transient is tissue impedance and the at least one characteristic of said electrical transient is a rate of change of the tissue impedance.

8. A method as in claim 1, wherein the RF energy parameters that are varied for individual pulses of the subsequent RF energy pulses comprise RF power output, current and voltage.

9. A method as in claim 1, further comprising the step of determining if the tissue responded to the first pulse of RF energy prior to the step of applying at least one subsequent RF energy pulse.

10. A method as in claim 9, wherein the step of applying at least one subsequent RF energy pulse includes the step of varying at least one of RF starting power, a magnitude of starting current, and a magnitude of starting voltage for the at least one subsequent RF energy pulse.

11. A method as in claim 1, further comprising the steps of:

measuring the at least one characteristic of the electrical transient that occurs at the end of one of the first pulse and the at least one subsequent RF energy pulse;

in accordance with the measured characteristic, determining whether to terminate the method for electrosurgically sealing tissue, or using the measured characteristic to determine a set of RF energy parameters for a subsequent RF energy pulse and repeating the applying step.

12. A method as in claim 11, wherein the set of RF energy parameters for the subsequent RF energy pulse comprise a magnitude of a starting RF power, a magnitude of a starting current, a magnitude of a starting voltage, and a duty cycle.

13. A method as in claim 11, wherein the electrical transient is an electrical impedance of the tissue.

14. A method as in claim 13, wherein the step of using the measured characteristic to determine the set of RF energy parameters for the subsequent RF energy pulse comprises a step of using the measured impedance value to readout the set of RF energy parameters from an entry in one of a plurality of lookup tables.

15. A method as in claim 10, wherein said one of the plurality of lookup tables is selected manually or automatically, based on a choice of an electrosurgical tool or instrument.

16. A method as in claim 3, further comprising the step of modifying predetermined pulses of the set of RF energy parameters in accordance with a control input from an operator.

17. A method as in claim 16, wherein the predetermined pulses of the set of RF energy parameters that are modified comprise a pulse power and a pulse starting voltage.

18. A method as in claim 1, further comprising the step of terminating a generation of subsequent RF energy pulses upon a determination that the electrical transient is absent.

20. A system as in claim 19, wherein the electrical characteristic is comprised of an electrical impedance.

21. A system as in claim 19, wherein the at least one characteristic of the electrical transient is the rate of change of the electrical transient.

22. A system as in claim 19, wherein said initial set of pulse parameters comprise a magnitude of starting power and a magnitude of a starting voltage.

23. A system as in claim 19, wherein said subsequent RF energy pulses are each varied in amplitude by a controlled amount from a previous RF energy pulse.

24. A system as in claim 19, further comprising one of a plurality of pulse parameter lookup tables that is readably coupled to said controller, and wherein said controller, when determining said initial set of pulse parameters, uses said impedance value to readout said initial set of pulse parameters from said one of the plurality of pulse parameter lookup tables.

25. A system as in claim 19, wherein said one of a plurality of pulse parameter lookup tables is selected manually or automatically, based on a choice of an electrosurgical tool or instrument.

26. A system as in claim 19, wherein said controller is responsive to a control input from an operator for modifying any one of said pulse parameters.

27. A system as in claim 19, wherein said controller is responsive to a determination that said electrical transient is absent for terminating a generation of subsequent RF energy pulses.

19. A system for electrosurgically sealing tissue, comprising an electrosurgical generator comprising an RF energy source and a controller for controlling the operation of an electrosurgical generator, said electrosurgical generator having an output for coupling to a surgical instrument comprising electrodes for coupling RF energy generated by said electrosurgical generator to tissue to be sealed;

said controller being operable for causing said electrosurgical generator to apply an initial pulse of RF energy to the tissue and for measuring a value of an electrical characteristic of the tissue in response to the applied initial pulse, said controller being responsive to the measured electrical characteristic for determining an initial set of pulse parameters for at least one subsequent pulse and for then varying the pulse parameters of individual pulses of further subsequent RF energy pulses in accordance with a change in the electrical characteristic of the tissue as determined from at least one characteristic of an electrical transient that occurs during each individual pulse of the subsequent RF energy pulses.