ULTRASONIC DEVICE FOR CUTTING AND COAGULATING WITH STEPPED OUTPUT

• US 20100036405A1
• Filed: 07/15/2009
• Published: 02/11/2010
• Est. Priority Date: 08/06/2008
• Status: Active Grant

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: Ethicon Endo-Surgery, Inc. (Johnson & Johnson)
• Inventors: Abbott, Daniel J., Messerly, Jeffrey D., Giordano, James R., Beetel, Robert J., Wiener, Eitan T., DiNardo, Brian
• Granted Patent: US 8,058,771 B2
• Time in Patent Office: Days
• US Class Current: 606/169
• CPC Class Codes: A61B 17/320092 with additional movable means for clamping or cutting tissue, e.g. with a pivoting jaw
• CPC Class Codes: A61B 2017/00026 Conductivity or impedance, e.g. of tissue
• CPC Class Codes: A61B 2017/00146 with multiple frequencies
• CPC Class Codes: A61B 2017/00176 Two pulses, e.g. second pulse having an effect different from the first one
• CPC Class Codes: A61B 2017/320093 additional movable means performing cutting operation
• CPC Class Codes: A61B 2017/320094 additional movable means performing clamping operation
• CPC Class Codes: A61B 2017/320095 with sealing or cauterizing means
• CPC Class Codes: A61B 2018/00303 active, e.g. with a motor creating vibrations
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/6847 mounted on an invasive device
• CPC Class Codes: B06B 1/0284 with consecutive, i.e. sequential generation, e.g. with frequency sweep
• CPC Class Codes: B06B 2201/76 Medical, dental

Abstract

Various embodiments are directed to an apparatus, system, and method for driving an end effector coupled to an ultrasonic transducer in a surgical instrument. The method comprises generating a first ultrasonic drive signal by a generator coupled to an ultrasonic drive system, actuating the ultrasonic transducer with the first ultrasonic drive signal for a first period, generating a second ultrasonic drive signal by the generator, and actuating the ultrasonic transducer with the second ultrasonic drive signal for a second period, subsequent to the first period. The first drive signal is different from the second drive signal over the respective first and second periods. The first and second drive signals define a step function waveform over the first and second periods. The apparatus comprises a generator configured to couple to an ultrasonic instrument. The system comprises a generator coupled to an ultrasonic instrument. The ultrasonic instrument comprises an ultrasonic drive system comprising an ultrasonic transducer coupled to a waveguide and an end effector coupled to the waveguide, and wherein the ultrasonic drive system is configured to resonate at a resonant frequency.

Claims

1. A method for driving an end effector coupled to an ultrasonic drive system of a surgical instrument, the method comprising:

generating a first ultrasonic drive signal by a generator coupled to an ultrasonic drive system, wherein the ultrasonic drive system comprises an ultrasonic transducer coupled to a waveguide and an end effector coupled to the waveguide, and wherein the ultrasonic drive system is configured to resonate at a resonant frequency;

actuating the ultrasonic transducer with the first ultrasonic drive signal for a first period;

generating a second ultrasonic drive signal by the generator; and

actuating the ultrasonic transducer with the second ultrasonic drive signal for a second period, subsequent to the first period;

wherein the first drive signal is different from the second drive signal over the respective first and second periods; and

wherein the first and second drive signals define a step function waveform over the first and second periods.

2. The method of claim 1, comprising:

generating a third ultrasonic drive signal by the generator; and

actuating the ultrasonic transducer with the third ultrasonic drive signal for a third period;

wherein the third drive signal is different from the first second drive signals over the first, second, and third periods; and

wherein the first, second, and third drive signals define a step function waveform over the first, second, and third periods.

3. The method of claim 2, wherein:

generating the first, second, and third ultrasonic drive signals comprises generating a corresponding first, second, and third drive current; and

actuating the ultrasonic transducer comprises;

actuating the ultrasonic transducer with the first drive current for the first period;

actuating the ultrasonic transducer with the second drive current for the second period; and

actuating the ultrasonic transducer with the third drive current for the third period.

4. The method of claim 1, comprising:

generating the first ultrasonic drive signal at a first frequency different from the resonant frequency;

actuating the ultrasonic transducer with the first ultrasonic drive signal at the first frequency for the first period to provide a first level of mechanical vibration to the end effector suitable for separating a first tissue from a second tissue;

generating the second ultrasonic drive signal at the resonant frequency; and

actuating the ultrasonic transducer with the second ultrasonic drive signal at the resonant frequency for the second period subsequent to the first period to provide a second level of mechanical vibration to the end effector suitable for transecting and sealing the first tissue.

5. The method of claim 4, wherein first frequency is substantially different from the resonant frequency, and wherein the first period is less than one second.

6. The method of claim 5, wherein the first frequency is defined by the following equation:

f₁=2*f_o;

wherein f₁ is the first frequency; and

wherein f_o is the resonant frequency.

7. The method of claim 5, wherein the first frequency is defined by the following equation:

f₁=f_o/2;

wherein f₁ is the first frequency; and

wherein f_o is the resonant frequency.

8. The method of claim 4, comprising automatically generating the second ultrasonic drive signal at the resonant frequency after the first period.

9. The method of claim 1, comprising:

monitoring a measurable characteristic of the ultrasonic drive system; and

generating any one of the first and second drive signals based on a measured characteristic.

10. The method of claim 9, wherein the measurable characteristic is impedance of the ultrasonic transducer.

11. The method of claim 9, wherein the measurable characteristic is impedance of a tissue portion contacting the end effector.

12. The method of claim 11, comprising:

generating a subtherapeutic radio frequency (RF) signal;

applying the RF signal to the tissue portion; and

measuring the impedance of the tissue portion.

13. An apparatus for driving an end effector coupled to an ultrasonic drive system of a surgical instrument, the method comprising:

a generator configured to couple to an ultrasonic drive system of an ultrasonic instrument, the ultrasonic drive system comprising an ultrasonic transducer coupled to a waveguide and an end effector coupled to the waveguide;

wherein the generator is configured to;

generate a first ultrasonic drive signal;

actuate the ultrasonic transducer with the first ultrasonic drive signal for a first period;

generate a second ultrasonic drive signal by the generator; and

actuate the ultrasonic transducer with the second ultrasonic drive signal for a second period, subsequent to the first period;

wherein the first drive signal is different from the second drive signal over the respective first and second periods; and

wherein the first and second drive signals define a step function waveform over the first and second periods.

14. The apparatus of claim 13, comprising a measurement module to monitor a measurable characteristic of the ultrasonic drive system, wherein the generator is configured to generate any one of the first and second drive signals based on a measured characteristic.

15. The apparatus of claim 14, wherein the measurement module comprises:

a radio frequency (RF) generator coupled to the end effector, the radio frequency generator configured to generate a subtherapeutic RF signal; and

a clamp arm assembly coupled to a distal end of the ultrasonic drive system, the clamp arm assembly comprising an electrically conductive portion forming a return electrode coupled to the RF generator, the clamp arm assembly being operatively coupled to the end effector to grasp tissue therebetween.

16. The apparatus of claim 14, wherein the measurement module comprises:

a voltage sense module;

a current sense module;

an analog-to-digital converter (ADC) coupled to the voltage sense module and the current sense module; and

a processor coupled to the ADC, the processor being configured to measure impedance.

17. A system for driving an end effector coupled to an ultrasonic system of a surgical instrument, the method comprising:

a generator; and

an ultrasonic instrument comprising an ultrasonic drive system coupled to the generator, the ultrasonic drive system comprising an ultrasonic transducer coupled to a waveguide and an end effector coupled to the waveguide;

wherein the generator is configured to;

generate a first ultrasonic drive signal;

actuate the ultrasonic transducer with the first ultrasonic drive signal for a first period;

generate a second ultrasonic drive signal by the generator; and

actuate the ultrasonic transducer with the second ultrasonic drive signal for a second period, subsequent to the first period;

wherein the first drive signal is different from the second drive signal over the respective first and second periods; and

wherein the first and second drive signals define a step function waveform over the first and second periods.

18. The system of claim 17, wherein the generator comprises a measurement module to monitor a measurable characteristic of the ultrasonic drive system, wherein the generator is configured to generate any one of the first and second drive signals based on a measured characteristic.

19. The system of claim 18, wherein the measurement module comprises:

a radio frequency (RF) generator coupled to the end effector, the radio frequency generator configured to generate a subtherapeutic RF signal; and

a clamp arm assembly coupled to a distal end of the ultrasonic drive system, the clamp arm assembly comprising an electrically conductive portion forming a return electrode coupled to the RF generator, the clamp arm assembly being operatively coupled to the end effector to grasp tissue therebetween.

20. The system of claim 18, wherein the measurement module comprises:

a voltage sense module;

a current sense module;

an analog-to-digital converter (ADC) coupled to the voltage sense module and the current sense module; and

a processor coupled to the ADC, the processor being configured to measure impedance.

21. A method of determining a change in tissue state in an ultrasonic surgical instrument, the method comprising:

sampling, by a processor, one or more drive signals of a generator for driving an ultrasonic transducer;

calculating, by the processor, a first weighted moving average of at least one of the sampled drive signals;

calculating, by the processor, a slope of the calculated first moving average of at least one of the sampled drive signals;

calculating, by the processor, a second weighted moving average for the slope of the sampled drive signal;

calculating, by the processor, a moving average for the slope;

comparing, by the processor, the second weighted moving average for the slope and the moving average for the slope; and

determining, by the processor, the occurrence of a change in tissue state based on the comparison.

22. The method of claim 21, comprising activating by the processor an output indicator when the change in tissue state occurs.

23. The method of claim 22, wherein activating the output indicator comprises activating any one of a visual, audible, and tactile feedback to notify a user of the ultrasonic surgical instrument of the occurrence of a change in tissue state.

24. The method of claim 22 comprising:

in response to the output indicator, disconnecting, by the processor, an output power of the generator.

25. The method of claim 22, comprising:

in response to the output indicator, reducing, by the processor, an output power of the generator.

26. The method of claim 22, comprising:

in response to the output indicator cycling, by the processor, an output power of the generator

27. The method of claim 22, comprising:

in response to the output indicator, pulsing, by the processor, the output power of the generator outputting a high-power momentary surge from the generator.

28. The method of claim 21, wherein calculating, by the processor, the first weighted moving average of at least one of the sampled drive signals comprises calculating, by the processor, an exponentially weighted moving average for the sampled drive signal in accordance with the following formula:

S_t=α

Y_t+(1−

α

)S<sub>t−

1</sub>

wherein,

S_t is a current moving average of the sampled drive signal;

S<sub>t−

1</sub> is a previous moving average of the sampled drive signal;

α

is a smoothing factor; and

Y_t is a current data point of the sampled drive signal.

29. The method of claim 28, wherein calculating, by the processor, the second weighted moving average for the slope of the sampled drive signal comprises calculating, by the processor, the second weighted moving average for the slope of the sampled drive signal in accordance with the following formula:

S′

_t=α

′

Y′

₁+(1−

α

′

)S′

<sub>t−

1</sub>

wherein,

S′

_t is a current moving average of a slope of the sampled drive signal;

S′

<sub>t−

1</sub> is a previous moving average of the slope of the sampled drive signal;

α

′

is a smoothing factor; and

Y′

_t is a current slope data point of the slope of the sampled drive signal.

30. The method of claim 21, wherein the sampled drive signal is a frequency signal and determining, by the processor, the occurrence of a change in tissue state based on the comparison comprises determining, by the processor, a frequency inflection point.

31. The method of claim 21, wherein the sampled drive signal is a voltage signal and determining, by the processor, the occurrence of a change in tissue state based on the comparison comprises determining, by the processor, a voltage drop point over at least two consecutive samples.