ELECTROSURGICAL SYSTEM AND METHOD HAVING ENHANCED TEMPERATURE MEASUREMENT

• US 20110270242A1
• Filed: 04/30/2010
• Published: 11/03/2011
• Est. Priority Date: 04/30/2010
• Status: Active Grant

• Current Assignee: ArthroCare Corporation (Smith & Nephew PLC)
• Original Assignee: ArthroCare Corporation (Smith & Nephew PLC)
• Inventors: Marion, Duane W.
• Granted Patent: US 8,696,659 B2
• Time in Patent Office: Days
• US Class Current: 606/35
• CPC Class Codes: A61B 18/1233 with circuits for assuring patient safety
• CPC Class Codes: A61B 18/148 having a short, rigid shaft for accessing the inner body transcutaneously, e.g. for neurosurgery or arthroscopy
• CPC Class Codes: A61B 2017/00084 Temperature
• CPC Class Codes: A61B 2017/00088 using thermistors
• CPC Class Codes: A61B 2018/00011 with fluids
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00744 Fluid flow
• CPC Class Codes: A61B 2018/00767 Voltage
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2018/1472 for use with liquid electrolyte, e.g. virtual electrodes
• CPC Class Codes: A61B 2218/007 Aspiration
• CPC Class Codes: A61B 90/06 Measuring instruments not otherwise provided for

Abstract

Electrosurgical systems and methods are described herein in which the temperature of a fluid within a body or joint space is determined and/or monitored despite the energy generated during treatment by an ablation probe. One or more temperature sensors are positioned along the probe proximally of the electrode assembly and measure the temperature of an electrically conductive fluid without being overly influenced by the surgical effect occurring proximate the electrode assembly. A controller automatically suspends energy delivery for one or more periods of time while the temperature is monitored.

Claims

1. An electrosurgical system for treating tissue at a target site with an electrosurgical probe, the probe comprising a shaft having a distal end and a proximal end, an active electrode terminal disposed near the distal end, said system comprising:

a high frequency power supply for delivery of high frequency energy to said active electrode terminal, the high frequency power supply coupled to the active electrode terminal and a return electrode;

a controller for receiving a temperature signal from a temperature sensor positioned in an electrically conductive fluid located at the target site and wherein the electrically conductive fluid provides a current path between the active electrode terminal and the return electrode and wherein the controller is operable to automatically suspend delivery of the high frequency energy to said active electrode terminal for at least one suspension period, and said controller further being operable to monitor the temperature signal during the at least one suspension period and wherein said controller is adapted to determine a measured temperature of said electrically conductive fluid located at the target site based on said temperature signal being monitored.

2. The system of claim 1 wherein said suspension period continues until the change in temperature signal versus time is less than a threshold value.

3. The system of claim 2 wherein said threshold value is 1 degree per 50 ms.

4. The system of claim 1 wherein said at least one suspension period is at least 250 ms.

5. The system of claim 1 wherein said controller is operable to suspend delivery of high frequency energy for a plurality of suspension periods.

6. The system of claim 5 wherein said plurality of suspension periods are determined by the controller according to a suspension frequency (F) equal to the number of suspension periods per second and wherein said suspension frequency (F) is between ⅓

and 2.

7. The system of claim 1 wherein said controller comprises a means to detachably and electrically couple with the electrosurgical probe.

8. The system of claim 6 wherein said controller is adapted to receive an input corresponding to a surgical procedure and said suspension frequency (F) is determined based on said input.

9. The system of claim 6 wherein said controller is adapted to determine said suspension frequency (F) based on a power output.

10. The system of claim 6 wherein said controller is adapted to determine said suspension frequency (F) based on said measured temperature and to increase the suspension frequency (F) when said measured temperature reaches a threshold temperature.

11. The system of claim 10 wherein said threshold temperature is 40 degrees Celsius.

12. The system of claim 1 further comprising:

a microprocessor for controlling the power supply; and

an analog-to-digital converter for converting the temperature signal to a digital signal readable by the microprocessor.

13. The system of claim 1, wherein said system comprises said probe, and said probe further comprises an aspiration lumen for removing fluid from said target site.

14. The system of claim 13, wherein said probe further comprises a fluid delivery element for delivering fluid to said target site and said fluid delivery element being coupled to a pump wherein the pump is operable to control fluid inflow to the target site, and wherein said controller being operable to control said pump and the fluid inflow in order to maintain the temperature of the fluid below a predetermined level.

15. An electrosurgical method for monitoring temperature during an electrosurgical procedure to ablate soft tissue comprising:

delivering high frequency energy to an active electrode terminal located at the distal end of an electrosurgical probe, said active electrode terminal being positioned in electrically conductive fluid during the procedure and wherein a current flow path from the active electrode, through the electrically conductive fluid, to a return electrode is created when the high frequency energy is delivered;

sensing a temperature of the electrically conductive fluid; and

automatically suspending the delivering step for at least one suspension period while sensing said temperature.

16. The method of claim 15 wherein said suspension period is at least 250 ms.

17. The method of claim 15 wherein said step of automatically suspending comprises suspending the delivering step for a plurality of suspension periods.

18. The method of claim 17 wherein the suspending step is performed according to a suspension frequency wherein said suspension frequency (F) is at least 1 period every 3 seconds and less than 2 periods per second.

19. The method of claim 18 wherein said suspension frequency (F) is determined based on power output.

20. The method of claim 18 wherein said suspension frequency (F) is determined based on receiving an input of a type of surgical procedure to be performed.

21. The method of claim 18 wherein said suspension frequency (F) is determined based on sensing the temperature, and said suspension frequency (F) is increased once the temperature reaches a threshold limit.

22. The method of claim 15 further comprising:

circulating fluid to the target site at a flowrate;

comparing the temperature to a desired temperature range; and

adjusting the flowrate based on the temperature.

23. The method of claim 15 wherein said applying step forms a plasma in the vicinity of the active electrode terminal.

24. The method of claim 15 wherein said target site is a joint.

25. The method of claim 15 wherein said automatically suspending step is performed by reducing the voltage difference between the active electrode terminal and the return electrode to less than 100 volts.

26. An electrosurgical system for treating tissue at a target site with an electrosurgical probe, the probe comprising a shaft having a distal end and a proximal end, an active electrode terminal disposed near the distal end, said system comprising:

a high frequency power supply for delivery of high frequency energy to said active electrode terminal, the high frequency power supply coupled to the active electrode terminal and a return electrode;

a controller for receiving a temperature signal from a temperature sensor positioned in an electrically conductive fluid located at the target site and wherein the electrically conductive fluid provides a current path between the active electrode terminal and the return electrode and wherein the controller is operable to automatically modify delivery of the high frequency energy to said active electrode terminal for at least one temperature-monitoring period, and said controller further being operable to monitor the temperature signal during the at least one temperature-monitoring period and wherein said controller is adapted to determine a measured temperature of said electrically conductive fluid located at the target site based on said temperature signal being monitored during said temperature-monitoring period.

27. The system of claim 26, wherein the controller is operable to automatically modify delivery of the high frequency energy for a plurality of temperature-monitoring periods, and wherein said automatic modification comprises substantially reducing the delivery of the high frequency energy.

28. The system of claim 27, wherein reducing the delivery of the high frequency output comprises reducing the high frequency output to less than 100 volts.