Adjustable impedance electrosurgical electrodes

• US 8,777,941 B2
• Filed: 05/10/2007
• Issued: 07/15/2014
• Est. Priority Date: 05/10/2007
• Status: Expired due to Fees

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Carlton, John, Odom, Darren
• Primary Examiner(s): DELLA, JAYMI E
• Application Number:
  US11/801,448
• Publication Number:
  US 20080281316A1
• Time in Patent Office: 2,623 Days
• Field of Search: 606/34, 606 37- 40, 606 50- 52
• US Class Current: 606/38
• CPC Class Codes: A61B 18/1206 Generators therefor
• 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 18/16 Indifferent or passive electrodes for grounding
• CPC Class Codes: A61B 2018/00107 Coatings on the energy applicator
• CPC Class Codes: A61B 2018/128 generating two or more frequencies
• CPC Class Codes: A61B 2018/147 Electrodes transferring energy by capacitive coupling, i.e. with a dielectricum between electrode and target tissue
• CPC Class Codes: A61B 2018/167 Passive electrodes capacitively coupled to the skin

Abstract

An electrosurgical system is disclosed. The electrosurgical system includes at least one electrosurgical electrode having a resistive element and a capacitive element configured in series. The electrosurgical system also including an electrosurgical generator configured to generate electrosurgical energy having a first frequency which generates a first impedance in the at least one electrode due to capacitive reactance of the capacitive element in series. The generator is further configured to adjust the first frequency to at least one other frequency to generate a different impedance in the at least one electrode due to capacitive reactance of the capacitive element in series, thereby adjusting the temperature of at least one electrosurgical electrode.

Claims

1. An electrosurgical system, comprising:

at least one electrosurgical electrode having a resistive element and a capacitive element configured in series; and

an electrosurgical generator configured to generate electrosurgical energy having a low frequency that generates an increase in impedance in the at least two electrosurgical electrodes due to capacitive reactances of each the capacitive elements in series to generate an increase in temperature of a plurality of layers of tissue within a patient, the electrosurgical generator being further configured to adjust the low frequency to a high frequency to generate a decrease in the impedance in the at least two electrosurgical electrodes due to the capacitive reactances of each of the capacitive elements in series that generates a decrease in the temperature of the plurality of layers of tissue, wherein each of the capacitive elements functions as a variable resistor adjustable based on a frequency of the electrosurgical energy applied by the electrosurgical generator and allows approximately a same current to pass through each of the plurality of layers of tissue clasped between the at least two electrosurgical electrodes to provide uniform heating across the plurality of layers of tissue.

2. The electrosurgical system according to claim 1, wherein each of the capacitive elements is a capacitive layer.

3. The electrosurgical system according to claim 2, wherein each of the capacitive layers is disposed on an outer conductive surface of the at least two electrosurgical electrodes.

4. The electrosurgical system according to claim 2, wherein each of the capacitive layers is disposed on an innermost conductive surface of the at least two electrosurgical electrodes.

5. The electrosurgical system according to claim 1, wherein the frequency of the electrosurgical energy is inversely proportional to an amount of heat generated by the at least two electrosurgical electrodes.

6. The electrosurgical system according to claim 1, wherein each of the capacitive elements is selected from the group consisting of aluminum, titanium dioxide, titanium oxide, tantalum oxide, aluminum oxide, and barium titranate.

7. An electrosurgical system, comprising:

an electrosurgical forceps for sealing a plurality of layers of tissue including 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 are configured to grasp the plurality of layers of tissue therebetween, wherein at least two layers of tissue of the plurality of layers of tissue have different individual impedances and each of the jaw members includes a sealing plate that communicates electrosurgical energy through the plurality of layers of tissue held therebetween, each of the sealing plates having a resistive element and a capacitive element configured in series; and

an electrosurgical generator configured to generate electrosurgical energy having a low frequency that generates an increase in impedance in at least one of the sealing plates due to capacitive reactances of each of the capacitive elements in series to generate an increase in temperature of the plurality of layers of tissue within a patient, the electrosurgical generator being further configured to adjust the low frequency to a high frequency to generate a decrease in the impedance in at least one of the sealing plates due to the capacitive reactances of each of capacitive elements in series that generates a decrease in the temperature of the plurality of layers of tissue, wherein each of the capacitive elements functions as a variable resistor adjustable based on a frequency of the electrosurgical energy applied by the electrosurgical generator and allows approximately a same current to pass through each the plurality of layers of tissue to provide uniform heating across the plurality of layers of tissue.

8. The electrosurgical system according to claim 7, wherein each of the capacitive elements is disposed on an outer conductive surface of each sealing plate.

9. The electrosurgical system according to claim 7, wherein each of the capacitive elements is disposed on an innermost conductive surface of each sealing plate.

10. The electrosurgical system according to claim 7, wherein the frequency of the electrosurgical energy is inversely proportional to an amount of heat generated by each sealing plate.

11. The electrosurgical system according to claim 7, wherein each of the capacitive elements is selected from the group consisting of aluminum, titanium dioxide, titanium oxide, tantalum oxide, aluminum oxide, and barium titranate.

12. A method for performing an electrosurgical procedure, comprising the steps of:

providing at least one electrosurgical electrodes having a resistive element and a capacitive element configured in series;

grasping a plurality of layers of tissue between the at least two electrosurgical electrodes, wherein at least two layers of tissue of the plurality of layers of tissue have different individual impedances;

applying electrosurgical energy having a high frequency to the plurality of layers of tissue of a patient to decrease a temperature of the plurality of layers of tissue within the patient; and

applying electrosurgical energy having a low frequency to the plurality of layers of tissue of the patient to increase the temperature of the plurality of layers of tissue, wherein each of the capacitive elements functions as a variable resisitor adjustable based on a frequency of the electrosurgical energy applied and allows approximately a same current to pass through each of the plurality of layers of tissue grasped between the at least two electrosurgical electrodes to provide uniform heating across the plurality of layers of tissue.