Devices and techniques for cutting and coagulating tissue
View Patent ↗Various embodiments are directed to an apparatus and method of driving an end effector coupled to an ultrasonic drive system of a surgical instrument. The method comprises generating at least one electrical signal. The at least one electrical signal is monitored against a first set of logic conditions.
1. A method of driving an end effector coupled to an ultrasonic drive system of a surgical instrument, the method comprising:
generating by a generator at least one electrical signal;
monitoring the at least one electrical signal;
comparing the monitored at least one electrical signal against a first set of logic conditions;
triggering a first response of the generator when the first set of logic conditions is met; and
determining from the at least one electrical signal a parameter associated with the surgical instrument;
wherein the determined at least one electrical signal parameter is a rate of temperature change of the end effector, the method comprising assessing the rate of temperature change of the end effector by calculating a frequency slope and comparing the frequency slope against a predetermined threshold.
2. The method of claim 1 , wherein the determined at least one electrical signal parameter is an impedance of the end effector, the method comprising resetting the generator when the impedance crosses a predetermined threshold.
3. The method of claim 1 , wherein the rate of temperature change is a rate of cooling.
4. The method of claim 1 , wherein the rate of temperature change is a rate of heating.
5. The method of claim 1 , comprising monitoring impedance of a transducer of the ultrasonic drive system in a dwell period while the frequency slope is substantially zero during pulsed activation.
6. The method of claim 1 , wherein monitoring the at least one electrical signal comprises sampling the at least one electrical signal with an analog-to-digital converter.
7. An ultrasonic drive system for driving an end effector of a surgical instrument, the ultrasonic drive system comprising:
a generator to generate at least one electrical signal; and
a circuit coupled to the generator, wherein the circuit is operative to:
monitor the at least one electrical signal;
compare the monitored at least one electrical signal against a first set of logic conditions;
trigger a first response of the generator when the first set of logic conditions is met; and
determine from the at least one electrical signal a parameter associated with the surgical instrument;
wherein the determined at least one electrical signal parameter is a rate of temperature change of the end effector and the circuit is operative to assess the rate of temperature change of the end effector by calculating a frequency slope and comparing the frequency slope against a predetermined threshold.
8. The ultrasonic drive system of claim 7 , wherein the determined at least one electrical signal parameter is an impedance of the end effector and the circuit is operative to reset the generator when the impedance crosses a predetermined threshold.
9. The ultrasonic drive system of claim 7 , wherein the rate of temperature change is a rate of cooling.
10. The ultrasonic drive system of claim 7 , wherein the rate of temperature change is a rate of heating.
11. The ultrasonic drive system of claim 7 , wherein the circuit is operative to monitor impedance of a transducer of the ultrasonic drive system in a dwell period while the frequency slope is substantially zero during pulsed activation.
12. The ultrasonic drive system of claim 7 , wherein the circuit comprises an analog-to-digital converter to sample the at least one electrical signal.
13. The ultrasonic drive system of claim 7 , wherein the circuit comprises a processor.
14. A surgical instrument, comprising:
an end effector; and
an ultrasonic drive system coupled to the end effector for driving the end effector, the ultrasonic drive system comprising:
a generator to generate at least one electrical signal; and
a circuit coupled to the generator, wherein the circuit is operative to:
monitor the at least one electrical signal;
compare the monitored at least one electrical signal against a first set of logic conditions;
trigger a first response of the generator when the first set of logic conditions is met; and
determine from the at least one electrical signal a parameter associated with the surgical instrument;
wherein the determined at least one electrical signal parameter is a rate of temperature change of the end effector and the circuit is operative to assess the rate of temperature change of the end effector by calculating a frequency slope and comparing the frequency slope against a predetermined threshold.
15. The surgical instrument of claim 14 , wherein the determined at least one electrical signal parameter is an impedance of the end effector and the circuit is operative to reset the generator when the impedance crosses a predetermined threshold.
16. The surgical instrument of claim 14 , wherein the rate of temperature change is a rate of cooling.
17. The surgical instrument of claim 14 , wherein the rate of temperature change is a rate of heating.
18. The surgical instrument of claim 14 , wherein the circuit is operative to monitor impedance of a transducer of the ultrasonic drive system in a dwell period while the frequency slope is substantially zero during pulsed activation.
19. The surgical instrument of claim 14 , wherein the circuit comprises an analog-to-digital converter to sample the at least one electrical signal.
20. The surgical instrument of claim 14 , wherein the circuit comprises a processor.