Method and system for controlling output of RF medical generator

• US 20040015163A1
• Filed: 05/01/2003
• Published: 01/22/2004
• Est. Priority Date: 10/23/1998
• Status: Active Grant

• Current Assignee: Covidien AG (Medtronic Plc)
• Original Assignee: Covidien AG (Medtronic Plc)
• Inventors: Schmaltz, Dale F., Heard, David N., Podhajsky, Ronald J., Buysse, Steven P., Shields, Chelsea, Wham, Robert H., Tetzlaff, Philip M., Schechter, David A., Keppel, David, Lawes, Kate R., Meagher, Edward C., Felton, Bret S.
• Granted Patent: US 7,137,980 B2
• Time in Patent Office: Days
• US Class Current: 606/34
• CPC Class Codes: A61B 18/1206 Generators therefor
• 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 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 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00726 Duty cycle
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2018/00827 Current
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/00892 Voltage

Abstract

A closed-loop control system is disclosed for use with an electrosurgical generator that generates electrosurgical energy. The closed loop control system includes a user interface for allowing a user to select at least one pre-surgical parameter, such as the type of surgical instrument operatively connected to the generator, the type of tissue and the desired surgical effect. A sensor module is also included for continually sensing at least one of electrical and physical properties proximate a surgical site and generating at least one signal relating thereto. The system also includes a control module for continually receiving the at least one selected pre-surgical parameter from the user interface and each of the signals from the sensor module, and processing each of the signals in accordance with the at least one pre-surgical parameter using at least one of a microprocessor, computer algorithm and a mapping. The control module generates at least one corresponding control signal relating to each signal from the sensor module, and relays the control signal to the electrosurgical generator for controlling the same. A method is also disclosed for performing an electrosurgical procedure at a surgical site on a patient. The method includes the steps of: applying at least one electrical pulse to the surgical site; continually sensing electrical and physical properties proximate the surgical site; and varying pulse parameters of individual pulses of the at least one pulse in accordance with the continually-sensed properties.

Claims

1. A closed-loop control system for use with an electrosurgical generator that generates electrosurgical energy including at least one pulse, said closed loop control system comprising:

a user interface for allowing a user to select at least one pre-surgical parameter, said at least one pre-surgical parameter including at least one of a type of surgical instrument operatively connected to the generator, type of tissue and desired surgical effect;

a sensor module for continually sensing at least one of electrical and physical properties proximate a surgical site and generating at least one signal relating thereto; and

a control module for continually receiving said selected at least one presurgical parameter from said user interface and each of said signals from said sensor module, and processing each of said signals in accordance with the at least one pre-surgical parameter using at least one of a microprocessor, computer algorithm and a mapping, said control module generating at least one corresponding control signal relating to each signal from said sensor module, and providing the at least one control signal to the electrosurgical generator for controlling the generator.

2. The closed-loop control system according to claim 1, wherein said user interface includes at least one additional sensor for automatically selecting a pre-surgical parameter of the at least one pre-surgical parameter.

3. The closed-loop control system according to claim 1, wherein said at least one control signal controls said generator to adjust at least one parameter of the generated electrosurgical energy in response to the signals received from said control module.

4. The closed-loop control system according to claim 3, wherein said at least one control signal is capable of controlling said generator to adjust voltage, current, pulse width, pulse frequency, amplitude, crest factor, duty cycle, repetition rate, and wave shape.

5. The closed-loop control system according to claim 1, wherein the generator includes a power source, and wherein the at least one control signal includes a power control signal for controlling the power source for adjusting a magnitude of an electrical characteristic of individual pulses of at least one pulse.

6. The closed-loop control system according to claim 1, wherein the at least one control signal adjusts wave shape parameters of individual pulses of the at least one pulse.

7. The electrosurgical generator according to claim 1, wherein the at least one control signal controls at least one of repetition rate and duty cycle of the at least one pulse.

8. The closed-loop control system according to claim 1, wherein the sensor module includes at least one of a voltage sensor, a current sensor, a temperature sensor, an RMS voltage sensor, an RMS current sensor and a leakage current sensor, and the microprocessor processes signals output by the RMS voltage sensor, the RMS current sensor and the leakage current sensor for deriving respective corresponding values for RMS voltage, RMS current and leakage current.

9. The closed-loop control system according to claim 1, wherein the sensor module is capable of sensing voltage, current, temperature, RMS voltage, RMS current and leakage current, and the microprocessor processes signals output by the RMS voltage sensor, the RMS current sensor and the leakage current sensor for deriving respective corresponding values for RMS voltage, RMS current and leakage current.

10. The closed-loop control system according to claim 1, wherein the sensor module further includes a voltage sensor for sensing voltage returned from the surgical site.

11. The closed-loop control system according to claim 1, wherein the sensor module further includes a current sensor for sensing current returned from the surgical site.

12. The closed-loop control system according to claim 1, wherein the sensor module further includes means for measuring electrical impedance.

13. The closed-loop control system according to claim 1, wherein the closed-loop control system further includes means for measuring changes in sensed temperature.

14. The closed-loop control system according to claim 1, wherein the closed-loop control system further includes means for processing information from the sensor module for determining electrical impedance at the surgical site.

15. The closed-loop control system according to claim 14, wherein the processing means measures changes in the electrical impedance.

16. The closed-loop control system according to claim 1, wherein the user interface further allows a user to enter commands for processing by the control module for controlling the electrosurgical generator to generate the energy having at least one of a target electrical parameter including at least one of voltage, current, power, frequency and amplitude;

pulse parameter including at least one of pulse width, duty cycle, crest factor and repetition rate; and

electrical parameter change in response to changes in at least one of sensed physical and electrical properties.

17. A method for performing an electrosurgical procedure at a surgical site on a patient, the method including the steps of:

applying at least one electrical pulse to the surgical site;

continually sensing electrical and physical properties proximate the surgical site; and

varying pulse parameters of individual pulses of the at least one pulse in accordance with the continually-sensed properties.

18. The method of claim 17, further comprising the step of continually processing the sensed properties;

and wherein the varying step includes varying the pulse parameters in accordance with the processed sensed properties.

19. The method of claim 17, wherein the varying step includes continually generating power supply control signals for controlling a magnitude of individual pulses of the at least one pulse in accordance with the continually-sensed properties.

20. The method of claim 17, wherein the varying step includes continually generating output stage control signals for controlling pulse parameters of pulses of the at least one pulse in accordance with the continually-sensed properties.

21. The method of claim 17, the method further comprising the steps of:

receiving operator initialization input settings;

processing the operator input settings; and

generating initial power supply control signals and output stage control signals in accordance with the processed input settings.

22. The method of claim 17, wherein the continually sensing step comprises the step of continually sensing at least one of voltage and current returned from the surgical site.

23. The method of claim 17, further comprising the step of varying the pulse parameters of individual pulses of the at least one pulse to maintain at least one of a selected voltage, electric current and electric power at the surgical site in response to the respective pulse.

24. 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 electric 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 a 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;

wherein the controller is further operable for measuring an electrical and a physical characteristic of the tissue in response to the individual pulses and for then varying the pulse parameters of subsequent individual pulses in accordance with the electrical and physical characteristics of the tissue.

25. A control system for use with an electrosurgical generator that generates electrosurgical energy including at least one pulse, the control system comprising:

a sensor module for sensing at least one of electrical and physical properties proximate a surgical site, and generating at least one signal relating thereto, said electrical and physical properties proximate the surgical site including at least one of power, current and voltage;

a first control module for controlling an inner control loop responsive to the at least one signal relating to said sensed properties, said first control module for controlling at least one electrical characteristic of the electrosurgical energy generated by the electrosurgical generator; and

a second control module for controlling an outer control loop responsive to the at least one signal from said sensor module relating to said electrical and physical properties said electrical and physical properties for controlling said second control module including at least one of temperature, impedance and energy.

26. A control system for use with an electrosurgical generator that generates electrosurgical energy including at least one pulse, the control system comprising:

a sensor module for sensing at least one property associated with a surgical site as one of a pre-surgical condition, concurrent surgical condition or a postsurgical condition and generating at least one signal relating thereto; and

a control module executable on a processor for receiving said at least one signal from said sensor module and processing each of said signals using at least one of a computer algorithm and a mapping and generating at least one control signal in accordance with the processing, said control module providing the at least one control signal to the electrosurgical generator for controlling the generator.

27. The control system according to claim 26, wherein the sensor module senses the at least one property during at least two of the pre-surgical condition, the concurrent surgical condition and the post-surgical condition.

28. The control system according to claim 26, wherein the at least one property sensed during the pre-surgical condition includes at least one of:

degree of opaqueness of tissue proximate the surgical site;

moisture content level of tissue; and

thickness of tissue.

29. The control system according to claim 26, wherein the processing includes determining type of tissue.

30. The control system according to claim 26, wherein the at least one property sensed during the concurrent surgical condition includes at least one of:

degree of opaqueness of tissue proximate the surgical site;

moisture content level of tissue;

thickness of tissue;

temperature of tissue, impedance of tissue;

current across tissue;

voltage across tissue;

power across tissue;

changes in degree of opaqueness of tissue;

changes in moisture content level of tissue;

changes in thickness of tissue;

changes in temperature of tissue;

changes in impedance of tissue;

changes in current across tissue;

changes in voltage across tissue; and

changes in power across tissue.

31. The control system according to claim 26, wherein the at least one property sensed during the post-surgical condition includes at least one of:

degree of opaqueness of tissue proximate the surgical site;

moisture content level of tissue;

thickness of tissue;

temperature of tissue; and

impedance of tissue.

32. The control system according to claim 26, wherein the at least one property sensed during the post-surgical condition is indicative of resulting quality of a tissue seal formed during the surgical procedure.

33. The control system according to claim 26, wherein the sensor module includes at least one of a light detector for detecting light generated by a light source and transmitted through tissue proximate the surgical site and a proximity sensor having sensing elements placed at opposite surfaces of tissue for sensing distance between the elements.