System and method for closed loop monitoring of monopolar electrosurgical apparatus

• US 7,927,328 B2
• Filed: 01/24/2007
• Issued: 04/19/2011
• Est. Priority Date: 01/24/2006
• Status: Active Grant

• Current Assignee: Covidien AG (Medtronic Plc)
• Original Assignee: Covidien AG (Medtronic Plc)
• Inventors: Orszulak, James H., Wham, Robert H.
• Primary Examiner(s): Dvorak; Linda C
• Assistant Examiner(s): SCOTT, AMANDA L
• Application Number:
  US11/657,174
• Publication Number:
  US 20070173806A1
• Time in Patent Office: 1,546 Days
• Field of Search: 606 32- 35, 606 37- 40
• US Class Current: 606/34
• CPC Class Codes: A61B 18/12 by passing a current through the tissue to be heated, e.g. high-frequency current
• 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 2017/00026 Conductivity or impedance, e.g. of tissue
• CPC Class Codes: A61B 2017/00137 Details of operation mode
• CPC Class Codes: A61B 2018/00589 Coagulation
• CPC Class Codes: A61B 2018/00642 with feedback, i.e. closed loop control
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00726 Duty cycle
• CPC Class Codes: A61B 2018/00773 Sensed parameters
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2018/00827 Current
• CPC Class Codes: A61B 2018/00869 Phase
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/00892 Voltage

Abstract

An electrosurgical system is disclosed comprising a generator configured to electrosurgical coagulation waveforms. The generator includes a closed loop control system for controlling the electrosurgical coagulation waveforms. The closed loop control system includes a sensor configured to sense a tissue property and/or an energy property and to transmit the tissue property and/or the energy property as one or more sensor signals having an amplitude. The control system also includes a gain controller configured to process the at least one sensor signal to reduce the amplitude of the sensor signals and to obtain a signal to noise ratio of the at sensor signals within a predetermine range. A microprocessor coupled to the generator and is configured to adjust the electrosurgical coagulation waveforms as a function of the sensor signals.

Claims

1. An electrosurgical system comprising:

a generator configured to generate at least one electrosurgical coagulation waveform, the generator includes a closed loop control system that controls the at least one electrosurgical coagulation waveform, the closed loop control system including;

a sensor configured to sense at least one of a tissue property and an energy property and transmit the at least one of a tissue property and an energy property to a gain controller as a voltage sensor signal having an amplitude;

the gain controller configured to process the voltage sensor signal to reduce the amplitude of the voltage sensor signal and obtain a signal to noise ratio of the voltage sensor signal within a predetermine range;

the gain controller being a voltage gain controller that includes;

a sensor voltage scaler control configured to scale the amplitude of the voltage sensor signal and to generate a scaled sensor signal;

a gain control configured to process a variable DC level control signal to generate a gain control signal; and

a multiplier coupled to the sensor voltage scaler and the gain control, the multiplier configured to multiply in real-time the scaled sensor signal and the gain control signal to normalize the voltage sensor signal independent of the amplitude thereof; and

a microprocessor coupled to the generator and configured to adjust the at least one electrosurgical coagulation waveform as a function of the voltage sensor signal.

2. An electrosurgical system according to claim 1, wherein the voltage gain controller includes:

an anti-alias filter configured to substantially block a harmonic radio frequency.

3. An electrosurgical system according to claim 1, wherein the microprocessor includes a buffer sized to store an integer multiple of a repetition rate of the voltage sensor signal.

4. An electrosurgical system according to claim 1, wherein the microprocessor is configured to calculate at least one of a RMS value, a peak value, and crest factor of the voltage sensor signal and adjust the at least one electrosurgical coagulation waveform as a function thereof.

5. An electrosurgical system comprising:

a generator configured to generate at least one electrosurgical coagulation waveform, the generator includes a closed loop control system which controls the at least one electrosurgical coagulation waveform, the closed loop control system including;

a sensor configured to sense at least one of a tissue property and an energy property and transmit the at least one of a tissue property and an energy property to a gain controller as a current sensor signal having an amplitude;

the gain controller configured to process the current sensor signal to reduce the amplitude of the current sensor signal and obtain a signal to noise ratio of the current sensor signal within a predetermine range;

the gain controller being a current gain controller that includes;

a sensor current scaler control configured to scale the amplitude of the current sensor signal and to generate a scaled sensor signal;

a gain control configured to process a variable DC level control signal to generate a gain control signal;

a multiplier configured to generate a multiplied signal as a function of the real-time the gain control signal;

a summer configured to generate a difference signal as a function of the multiplied signal and the current sensor signal; and

an operational amplifier configured to amplify the difference signal to normalize the current sensor signal independent of the amplitude thereof; and

a microprocessor coupled to the generator and configured to adjust the at least one electrosurgical coagulation waveform as a function of the current sensor signal.

6. An electrosurgical system according to claim 5, wherein the current gain controller includes:

an input limiter to provide surge protection for the operational amplifier.

7. An electrosurgical system according to claim 5, wherein the current gain controller includes:

an anti-alias filter configured to substantially block a harmonic radio frequency.

8. An electrosurgical system according to claim 5, wherein the microprocessor includes a buffer sized to store an integer multiple of a repetition rate of the current sensor signal.

9. An electrosurgical system according to claim 5, wherein the microprocessor is configured to calculate at least one of a RMS value, a peak value, and crest factor of the current sensor signal and adjust the at least one electrosurgical coagulation waveform as a function thereof.

10. A closed loop control system for controlling at least one electrosurgical coagulation waveform, the closed loop control system including:

a sensor configured to sense at least one of a tissue property and an energy property and transmit the at least one of a tissue property and an energy property to a gain controller as a voltage sensor signal having an amplitude;

the gain controller configured to process the voltage sensor signal to reduce the amplitude of the sensor signal and to obtain a signal to noise ratio of the voltage sensor signal within a predetermine range;

the gain controller being a voltage gain controller that includes;

a sensor voltage scaler control configured to scale the amplitude of the voltage sensor signal and to generate a scaled sensor signal;

a gain control configured to process a variable DC level control signal to generate a gain control signal; and

a multiplier coupled to the sensor voltage scaler and the gain control, the multiplier configured to multiply in real-time the scaled sensor signal and the gain control signal to normalize the voltage sensor signal independent of the amplitude thereof; and

a microprocessor coupled to the generator configured to adjust the at least one electrosurgical coagulation waveform as a function of the voltage sensor signal.

11. A closed loop control system according to claim 10, wherein the voltage gain controller includes:

an anti-alias filter configured to substantially block a harmonic radio frequency.

12. A closed loop control system for controlling at least one electrosurgical coagulation waveform, the closed loop control system including:

a sensor configured to sense at least one of a tissue property and an energy property and transmit the at least one of a tissue property and an energy property to a gain controller as a current sensor signal having an amplitude;

the gain controller configured to process the sensor signal to reduce the amplitude of the current sensor signal and to obtain a signal to noise ratio of the current sensor signal within a predetermine range;

the gain controller being a current gain controller that includes;

a sensor current scaler control configured to scale the amplitude of the current sensor signal and to generate a scaled sensor signal;

a gain control configured to process a variable DC level control signal to generate a gain control signal;

a multiplier configured to generate a multiplied signal as a function of the real-time the gain control signal;

a summer configured to generate a difference signal as a function of the multiplied signal and the current sensor signal; and

an operational amplifier configured to amplify the difference signal to normalize the current sensor signal independent of the amplitude thereof; and

a microprocessor coupled to the generator configured to adjust the at least one electrosurgical coagulation waveform as a function of the current sensor signal.

13. A closed loop control system according to claim 12, wherein the current gain controller includes:

an input limiter to provide surge protection for operational amplifier.

14. An electrosurgical system according to claim 12, wherein the current gain controller includes:

an anti-alias filter configured to substantially block a harmonic radio frequency.

15. A method for controlling at least one electrosurgical coagulation waveform, the closed loop control system including:

sensing at least one of a tissue property and an energy property and transmitting the at least one of a tissue property and an energy property as a sensor signal having an amplitude;

processing the sensor signal to reduce the amplitude of the sensor signal and to obtain a signal to noise ratio of the sensor signal within a predetermine range; and

adjusting the at least one electrosurgical coagulation waveform as a function of the sensor signal.

16. A method according to claim 15, further comprising the steps of:

scaling the amplitude of the sensor signal to generate a scaled sensor signal;

processing a variable DC level control signal to generate a gain control signal; and

multiplying in real-time the sealed sensor signal and the gain control signal to normalize the sensor signal independent of the amplitude thereof.

17. A method according to claim 16, further comprising the steps of

generating a difference signal as a function of the multiplied signal and the current sensor signal;

and

amplifying the difference signal to normalize the current sensor signal independent of the amplitude thereof.

18. A method according to claim 15, further comprising the step of:

calculating one of a RMS value, a peak value, and crest factor of the sensor signal and adjusting the at least one electrosurgical coagulation waveform as a function thereof.