Devices and techniques for cutting and coagulating tissue
Various embodiments are directed to a 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. A first response is triggered when the first set of logic conditions is met. A parameter is determined from the at least one electrical signal.
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 against a first set of logic conditions;
triggering a first response of the generator when the first set of logic conditions is met;
determining from the at least one electrical signal a parameter associated with the surgical instrument,
wherein the determined parameter is indicative of a temperature change of the end effector; and
monitoring impedance of a transducer of the ultrasonic drive system in a dwells region during pulsed activation.
2. The method of claim 1 , further comprising:
resetting the generator when the determined parameter crosses a predetermined threshold.
3. The method of claim 1 , wherein the determined parameter is a rate of temperature change of the end effector assessed by calculating a frequency slope, the method further comprising:
comparing the frequency slope against a predetermined threshold.
4. The method of claim 3 , wherein the rate of temperature change is a rate of cooling.
5. The method of claim 3 , wherein the rate of temperature change is a rate of heating.
6. The method of claim 1 , wherein the determined parameter is proportional to a frequency slope, and wherein the determined parameter is a rate of temperature change of the end effector.
7. The method of claim 6 , wherein the rate of temperature change is a rate of cooling.
8. The method of claim 6 , wherein the rate of temperature change is a rate of heating.
9. 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;
determining from the at least one electrical signal a parameter associated with the end effector;
comparing the determined parameter against a predetermined parameter,
wherein the determined parameter is indicative of a temperature change of the end effector; and
monitoring impedance of the end effector of the ultrasonic drive system in a dwells region during pulsed activation.
10. The method of claim 9 , wherein the determined parameter comprises the impedance of the end effector.
11. The method of claim 10 , comprising resetting the generator when the impedance crosses a predetermined threshold.
12. The method of claim 9 , wherein the determined parameter is a rate of temperature change of the end effector.
13. The method of claim 12 , wherein the rate of temperature change is selected from the group consisting of a rate of cooling and a rate of heating.
14. 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 against a first set of logic conditions;
triggering a first response of the generator when the first set of logic conditions is met;
determining a frequency slope of the at least one electrical signal; and
monitoring impedance of the end effector of the ultrasonic drive system in a dwells region during pulsed activation.
15. The method of claim 14 , wherein the frequency slope is proportional to a rate of temperature change of the end effector.
16. The method of claim 15 , wherein the rate of temperature change is a rate of cooling.
17. The method of claim 15 , wherein the rate of temperature change is a rate of heating.
18. The method of claim 14 , comprising comparing the frequency slope against a predetermined threshold.