Vessel Sealing System Using Capacitive RF Dielectric Heating

• US 20100312235A1
• Filed: 07/29/2010
• Published: 12/09/2010
• Est. Priority Date: 03/02/2004
• Status: Active Grant

• Current Assignee: Covidien AG (Medtronic Plc)
• Original Assignee: Covidien AG (Medtronic Plc)
• Inventors: Bahney, Timothy J.
• Granted Patent: US 8,348,948 B2
• Time in Patent Office: Days
• US Class Current: 606/33
• 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 2018/00136 with polymer
• CPC Class Codes: A61B 2018/00345 Vascular system
• CPC Class Codes: A61B 2018/00404 Blood vessels other than those in or around the heart
• CPC Class Codes: A61B 2018/00619 Welding
• CPC Class Codes: A61B 2018/1432 curved
• CPC Class Codes: A61B 2018/147 Electrodes transferring energy by capacitive coupling, i.e. with a dielectricum between electrode and target tissue

Abstract

An electrosurgical system for sealing vessels using capacitive (RF) dielectric heating and a method thereof are provided. The system includes an electrosurgical instrument having an end effector with parallel plate electrodes that will clamp onto a vessel and maintain a specified gap distance; however, the electrodes will be coated with a non-conductive dielectric material. Such an end effector will ensure that direct conduction between the electrodes does not occur through tissue or fluids and effectively creates a parallel plate capacitor with a dielectric, e.g., tissue and coating, in between the plates. The electrosurgical instrument will be activated with an AC signal at a specified RF frequency, e.g., a Debye resonance frequency, via an electrosurgical generator. An effective AC current will flow through the tissue and cause heating due to fictional losses from rotating polar molecules in the tissue.

Claims

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

determining a type of tissue to be sealed; and

applying RF energy to the tissue at a predetermined frequency based on the type of tissue.

2. The method according to claim 1, wherein the predetermined frequency is a Debye resonance frequency of the tissue to be sealed.

3. The method according to claim 1, further comprising the steps of:

measuring a temperature of the tissue;

determining a shifted Debye resonance frequency based on the measured temperature; and

applying subsequent RF energy at the shifted Debye resonance frequency.

4. The method according to claim 2, further comprising the steps of:

determining a shifted Debye resonance frequency based on time of the applied RF energy; and

applying subsequent RF energy at the shifted Debye resonance frequency.

5. The method according to claim 1, wherein the applying step includes generating an AC electric field that causes energy to flow at the predetermined frequency through the tissue to be sealed.

6. The method according to claim 5, further comprising the steps of:

sensing a strength of the AC electric field; and

controlling the application of RF energy to the tissue based on the sensed strength of the AC electric field.

7. The method according to claim 1, wherein the determining step includes referencing a look-up table including a plurality of predetermined frequencies, each predetermined frequency being correlated to a tissue type.

8. The method according to claim 1, wherein the determining step further comprises the steps of

referencing a look-up table including a plurality of predetermined frequencies versus temperature curves;

generating a signal based on a sensed temperature of tissue; and

selecting the predetermined frequency from the look-up table based on the signal.

9. The method according to claim 1, wherein the applying step includes applying RF energy to the tissue via an end effector having opposing jaw members adapted to connect to a source of electrosurgical energy.

10. The method according to claim 9, wherein each jaw member includes an electrode having a dielectric coating, wherein the dielectric coating has a predetermined frequency different than the predetermined frequency of the tissue.

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

determining a type of tissue to be sealed;

applying RF energy to the tissue, the RF energy being applied at a Debye resonance frequency of the tissue being sealed based on the determined tissue type;

determining a shift in the Debye resonance frequency of the tissue being sealed; and

regulating the application of RF energy to the tissue to cause energy to flow through the tissue being sealed at the shifted Debye resonance frequency based on the determined shift.

12. A method according to claim 11, wherein the applying step includes generating an AC electric field that causes energy to flow at the Debye resonance frequency through the tissue to be sealed.

13. A method according to claim 11, further comprising the step of:

referencing a look-up table including a plurality of Debye resonance frequencies prior to the applying step, each Debye resonance frequency being correlated to a tissue type.

14. The method according to claim 11, further comprising the steps of:

referencing a look-up table including a plurality of Debye resonance frequencies versus temperature curves prior to the applying step;

generating a signal based on a sensed temperature of tissue; and

selecting the Debye resonance frequency from the look-up table based on the signal.

15. The method according to claim 11, further comprising the step of:

providing an electrosurgical instrument for sealing tissue, the electrosurgical instrument comprising;

an end effector having opposing jaw members, at least one of the jaw members movable relative to one another from a first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members cooperate to grasp tissue therebetween, at least one jaw member adapted to connect to a source of electrosurgical energy;

grasping tissue between the jaw members; and

applying RF energy to the grasped tissue at the Debye resonance frequency of the tissue.

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

providing an electrosurgical instrument for sealing tissue, the electrosurgical instrument comprising:

an end effector having opposing jaw members, at least one of the jaw members movable relative to one another from a first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members cooperate to grasp tissue therebetween, at least one jaw member adapted to connect to a source of electrosurgical energy;

determining a type of tissue to be sealed;

applying RF energy from the source of electrosurgical energy to the tissue via the jaw members, the RF energy applied at a predetermined frequency based on the type of tissue;

determining a shift in the predetermined frequency of the tissue being sealed; and

regulating the application of RF energy from the electrosurgical energy source to the tissue to cause energy to flow through the tissue being sealed at the shifted predetermined frequency based on the determined shift.

17. The method according to claim 16, wherein the predetermined frequency is a Debye resonance frequency of the tissue to be sealed.

18. The method according to claim 16, further comprising the steps of:

measuring a temperature of the tissue; and

determining the shift in the predetermined frequency based on the measured temperature.

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

determining the shift in the predetermined frequency based on the amount of time the RF energy is applied.

20. The method according to claim 16, wherein the determining a type of tissue to be sealed step includes referencing a look-up table including a plurality of predetermined frequencies, each predetermined frequency being correlated to a tissue type.