Electrosurgical system and method

• US 20060041251A1
• Filed: 08/12/2005
• Published: 02/23/2006
• Est. Priority Date: 08/17/2004
• Status: Active Grant

• Current Assignee: Encision Inc.
• Original Assignee: Encision Inc.
• Inventors: Newton, David W., Odell, Roger C.
• Granted Patent: US 7,465,302 B2
• Time in Patent Office: Days
• US Class Current: 606/32
• CPC Class Codes: A61B 18/1233 with circuits for assuring patient safety

Abstract

A system and method for performing an electrosurgical procedure are disclosed. The method includes applying an active electrode to a patient and placing a return electrode on the patient so as to create a current path in tissue of the patient between the active electrode and the return electrode. A conductive element, which is operatively coupled to the active electrode, is coupled to a reference voltage with a low impedance path and a voltage is imparted to the active electrode so as to generate current in the current path. Any undesirable current flow that would otherwise flow from the active electrode to the reference voltage through the patient is limited to reduce a risk of harm to the patient.

Claims

1. A method for performing an electrosurgical procedure comprising:

applying an active electrode to a patient, the active electrode being operatively coupled to a conductive body of a surgical instrument;

placing a return electrode on the patient so as to create a current path in tissue of the patient between the active electrode and the return electrode;

placing a reference electrode on the patient a distance from the return electrode so as to substantially isolate the reference electrode from the return electrode;

coupling the conductive body to the reference electrode with a low impedance path so as to limit a difference between a voltage of the patient and a voltage of the working element; and

imparting a voltage to the active electrode so as to generate current in the current path, wherein the current in the current path alters tissue of the patient.

2. A method for performing an electrosurgical procedure comprising:

applying an active electrode to a patient, the active electrode being operatively coupled to a conductive body of a surgical instrument;

placing a return electrode on the patient so as to create a current path in tissue of the patient between the active electrode and the return electrode;

coupling the conductive body to the return electrode with a low impedance path;

imparting a voltage to the active electrode so as to generate current in the current path, wherein the current in the current path alters some tissue of the patient; and

limiting any undesirable current flow that would otherwise flow, absent the limiting, from the active electrode to the reference voltage through the patient, conductive body and the low impedance path.

3. A system for performing an electrosurgical procedure comprising:

an electrosurgical instrument comprising an active electrode and a conductive body, wherein the active electrode is operatively coupled to the conductive body, wherein the active electrode is configured to impart, when coupled with an electrosurgical generator, a voltage to a region of a patient so as to alter tissue in the region of the patient;

a return electrode coupled between the patient and the electrosurgical generator;

a low impedance current path between the conductive body and a reference voltage;

current limiting means for limiting current flow from the active electrode to the reference voltage through the patient, conductive body and the low impedance path; and

a monitor configured to provide a control signal to the electrosurgical generator that is indicative of conduction between the conductive body and the active electrode, and wherein the monitor is configured to provide the control signal at a first selected level that permits the electrosurgical generator to continue to impart the voltage to the active electrode at a non-zero level in response to a non-zero level of undesirable, yet tolerable, conduction between the conductive body and the active electrode.

4. The system of claim 3, wherein the monitor is configured to provide the control signal at a second selected level that prompts the electrosurgical generator to alter the voltage to the active electrode in response to an intolerable non-zero level of conduction between the conductive body and the active electrode.

5. The system of claim 4, wherein the first selected level includes an absence of a voltage and the second selected level includes the presence of a voltage.

6. The system of claim 4, wherein the monitor is configured to provide the control signal at the second selected level to the electrosurgical generator in response to the non-zero level of conduction substantially matching at least one undesired conduction characteristic.

7. The system of claim 6 wherein the at least one undesired conduction characteristic includes a conduction characteristic selected from the group consisting of a power level sustained for a predetermined period of time, a current level sustained for a predetermined period of time, a current surge and a power surge.

8. The system of claim 6, wherein the at least one undesired conduction characteristic includes a plurality of current levels, wherein each of the plurality of current levels is associated with a corresponding one of a plurality of durations of time.

9. The system of claim 6, wherein the at least one undesired conduction characteristic includes a plurality of power levels, wherein each of the plurality of power levels is associated with a corresponding one of a plurality of durations of time.

10. The system of claim 3, wherein the monitor includes a first channel configured to monitor the conduction between the conductive body and the active electrode by measuring current in the low impedance current path.

11. The system of claim 3, wherein the low impedance current path is less than 100 ohms.

12. The system of claim 11, wherein the low impedance current path is greater than or equal to 15 ohms and less than or equal to 50 ohms.

13. The system of claim 3, wherein reference voltage is a voltage of the return electrode.

14. The system of claim 13, wherein the current limiting means includes an insulating sheath interposed between the conductive body and the patient.

15. The system of claim 10, wherein the current limiting means includes means for limiting a difference between a voltage of the conductive element and a voltage of the patient.

16. The system of claim 15, wherein the means for limiting the difference between the voltage of the conductive element and the voltage of the patient includes means for providing the reference voltage at a voltage that is substantially the same as a portion of the patient.

17. The system of claim 16, wherein the means for providing the reference voltage at a voltage that is substantially the same as a portion of the patient includes a reference electrode configured to be coupled to another region of the patient.

18. The system of claim 16 wherein the means for limiting the difference between the voltage of the conductive element and the voltage of the patient includes:

a second return electrode coupled between the patient and the electrosurgical generator, and wherein the monitor is configured to monitor;

an impedance of the patient between the two return electrodes; and

a return current in at least one of the two return electrodes, wherein the reference voltage is derived, at least in part, from the impedance of the patient and the return current.

19. The system of claim 3, wherein the electrosurgical instrument includes an electrode assembly operatively coupled to the conductive element, the electrode assembly including:

the active electrode;

an insulating layer surrounding a substantial portion of the active electrode;

a

a shield surrounding a substantial portion of the insulating layer so as to protect the insulating layer; and

and an outer insulating layer disposed so as to substantially insulate the shield from the conductive body.

20. The system of claim 19 wherein the monitor includes a second channel configured to couple the shield and the return electrode via another low impedance path, wherein the monitor is configured to monitor a level of conduction between the shield and the return electrode, and wherein the monitor is configured to send the control signal at a level that prompts the electrosurgical generator to alter the voltage to the active electrode in response to the level of conduction between the shield and the return electrode substantially matching at least one other undesired conduction characteristic.

21. A system for performing an electrosurgical procedure comprising:

an electrosurgical generator configured to provide a range of surgical-level voltages that are sufficient to alter tissue of a patient;

an electrosurgical instrument comprising an active electrode and a conductive body, wherein the active electrode is operatively coupled to the conductive body and the active electrode is configured to conductively couple to the electrosurgical generator so as to be capable of altering tissue of the patient with the surgical-level voltages;

a return electrode configured to be coupled between the patient and the electrosurgical generator;

a reference electrode coupled to a reference voltage, wherein the reference voltage is electrically isolated from the return electrode and is selected so as to be substantially the same as a patient voltage; and

a low impedance monitor coupled between the conductive body of the electrosurgical instrument and the reference electrode, wherein the low impedance monitor is configured to detect undesirable current between the active electrode and the working element and to provide a control signal to the electrosurgical generator that allows the electrosurgical generator to continue to provide a voltage within the range of the surgical-level voltages while there are tolerable non-zero levels of the undesirable current between the active electrode and the working element.