A method of using a surgical instrument to deliver electrosurgical energy according to a target impedance rise rate, wherein the surgical instrument comprises:
- an end effector comprising:
- an ultrasonic blade configured to ultrasonically oscillate against tissue;
- and a clamp arm configured to pivot relative to the ultrasonic blade;
- a generator configured to deliver electrosurgical energy to the end effector based on generating a drive signal;
- an electrode configured to deliver the electrosurgical energy to the end effector;
- an ultrasonic transducer acoustically coupled to the ultrasonic blade, the ultrasonic transducer configured to ultrasonically oscillate the ultrasonic blade in response to a drive signal generated by the generator;
- and a control circuit coupled to the end effector and wherein the method comprises:
- controlling, by the control circuit, the generator to apply power according to a tissue impedance algorithm comprising the steps of:
- applying, by the generator, a first power level to reach a first tissue impedance point;
- terminating, by the generator, application of the first power level for a first dwell time;
- determining, by the control circuit, a second tissue impedance point;
- applying, by the generator, a second power level to reach the second tissue impedance point;
- terminating, by the generator, application of the second power level for a second dwell time;
- determining, by the control circuit, a third tissue impedance point;
- applying, by the generator, a third power level to reach the third tissue impedance point to achieve the target impedance rise rate.