Combination ultrasonic and electrosurgical instrument with adjustable energy modalities and method for limiting blade temperature

A method of determining an ultrasonic blade temperature of a surgical instrument having an ultrasonic blade configured to be driven by an ultrasonic energy, the method comprising:

• (a) measuring a first ultrasonic frequency of the ultrasonic blade;
• (b) measuring a second ultrasonic frequency of the ultrasonic blade after measuring the first ultrasonic frequency;
• (c) calculating a frequency parameter change between the measured first and second ultrasonic frequencies of the ultrasonic blade;
• (d) correlating the frequency parameter change of the ultrasonic blade to the temperature of the ultrasonic blade to thereby determine the temperature of the ultrasonic blade;
• (e) in response to determining that the temperature of the ultrasonic blade has reached a predetermined temperature limit, setting a predetermined frequency parameter change threshold;
• and
• (f) adjusting at least one power parameter of the ultrasonic energy based on the determined temperature of the ultrasonic blade to limit the ultrasonic energy to the predetermined frequency parameter change threshold.

A method of limiting an ultrasonic blade temperature of a surgical instrument with an ultrasonic blade configured to apply ultrasonic energy to tissue, the method comprising:

• (a) activating the ultrasonic energy to initiate sealing of the tissue;
• (b) measuring an initial ultrasonic frequency of the ultrasonic blade;
• (c) measuring a first interrogation ultrasonic frequency of the ultrasonic blade;
• (d) calculating a frequency parameter change based on the measured initial ultrasonic frequency and the measured first interrogation ultrasonic frequency;
• (e) correlating the calculated frequency parameter change to a current temperature of the ultrasonic blade based on a plurality of predetermined data correlations of blade temperature to frequency parameter change;
• (f) determining whether the current temperature of the ultrasonic blade has reached a predetermined temperature limit;
• (g) in response to determining that the current temperature of the ultrasonic blade has reached the predetermined temperature limit, setting a predetermined frequency parameter change threshold;
• and
• (h) adjusting at least one power parameter of the ultrasonic energy to limit the ultrasonic energy to the predetermined frequency parameter change threshold.