Ultrasonic surgical instrument with features for forming bubbles to enhance cavitation

1. A method of providing cavitation in a tissue or other anatomical structure at a surgical site in a patient, the method comprising:

(a) activating an ultrasonic element at a first vibrational profile to generate microbubbles in a fluid at a surgical site in a patient; and

(b) activating the ultrasonic element at a second vibrational profile to grow the microbubbles and burst the microbubbles, to thereby induce erosion by cavitation in the tissue or other anatomical structure at the surgical site;

wherein the first vibrational profile includes ultrasonic vibrations at a first amplitude;

wherein the second vibrational profile includes ultrasonic vibrations at a second amplitude;

wherein the first amplitude is greater than the second amplitude.

2. The method of claim 1 , further comprising introducing the fluid to the surgical site from an external fluid source.

3. The method of claim 2 , wherein the fluid is introduced to the surgical site from an external fluid source via the ultrasonic element.

4. The method of claim 1 , further comprising maintaining the first vibrational profile for a first activation duration.

5. The method of claim 4 , wherein the ultrasonic element is vibrated substantially consistently at the first amplitude throughout the first activation duration.

6. The method of claim 4 , further comprising maintaining the second vibrational profile for a second activation duration.

7. The method of claim 6 , wherein the second activation duration is longer than the first activation duration such that the second vibrational profile is activated for a longer duration than the first vibrational profile.

8. The method of claim 4 , further comprising ceasing activation of the ultrasonic element for a first pause duration after the first activation duration.

9. The method of claim 8 , wherein the first pause duration allows the microbubbles generated by the first vibrational profile to stabilize.

10. The method of claim 9 , further comprising ceasing activation of the ultrasonic element for a second pause duration after activating the ultrasonic element at the second vibrational profile.

11. The method of claim 10 , wherein ceasing activation of the ultrasonic element for the second pause duration decreases the circulation of the fluid which prevents the microbubbles from being swept away from the surgical site.

12. The method of claim 10 , wherein the second pause duration is longer than the first pause duration.

13. The method of claim 10 , wherein the second pause duration is the same duration as the first pause duration.

14. The method of claim 10 , wherein the second pause duration is shorter than the first pause duration.

15. The method of claim 10 , further comprising adjusting the first and second pause durations to reduce thermal effects.

16. The method of claim 10 , further comprising activating a third vibrational profile to further grow the microbubbles after the second pause duration, wherein the third vibrational profile has a third amplitude that is equivalent to the second amplitude.

17. The method of claim 16 , further comprising:

(a) maintaining the second vibrational profile for a second activation duration; and

(b) maintaining the third vibrational profile for a third activation duration, wherein the third activation duration is longer than the second activation duration of time.

18. A method of providing cavitation in a tissue or other anatomical structure at a surgical site in a patient, the method comprising:

(a) activating an ultrasonic element at a high amplitude to generate microbubbles in a fluid at a surgical site in a patient;

(b) transitioning the ultrasonic element from the high amplitude to a low amplitude to grow and burst the microbubbles in the fluid at the surgical site, wherein transitioning the ultrasonic element from the high amplitude to the low amplitude is gradual, wherein activating the ultrasonic element at the low amplitude induces erosion by cavitation in the tissue or other anatomical structure at the surgical site;

(c) transitioning the ultrasonic element from the low amplitude to a zero amplitude; and

(d) maintaining an inactivity period at the zero amplitude to decrease gross circulation in the fluid to prevent the microbubbles from being swept away from the surgical site.

19. The method of claim 18 , wherein the ultrasonic element is activated at the high amplitude for a shorter duration than at the low amplitude.

20. A method of providing cavitation in a tissue or other anatomical structure at a surgical site in a patient, the method comprising:

(a) initiating a first vibration period, wherein the first vibration period comprises:

(i) activating an ultrasonic element at a high amplitude to generate microbubbles in a fluid at a surgical site in a patient,

(ii) transitioning the ultrasonic element from the high amplitude to a low amplitude to grow and burst the microbubbles in the fluid at the surgical site, wherein transitioning the ultrasonic element from the high amplitude to the low amplitude is gradual, wherein activating the ultrasonic element at the low amplitude induces erosion by cavitation in the tissue or other anatomical structure at the surgical site, and

(iii) transitioning the ultrasonic element from the low amplitude to a zero amplitude;

(b) initiating an inactivity period after reaching the zero amplitude to decrease gross circulation in the fluid to prevent the microbubbles from being swept away from the surgical site; and

(c) initiating a second vibration period, wherein the second vibration period comprises:

(i) activating the ultrasonic element at the low amplitude to further grow the microbubbles, and

(ii) transitioning the ultrasonic element from the low amplitude to the zero amplitude,

wherein the second vibration period is longer than the first vibration period.