Method for detecting transverse vibrations in an ultrasonic hand piece

• US 20020052616A1
• Filed: 09/14/2001
• Published: 05/02/2002
• Est. Priority Date: 10/20/2000
• Status: Active Grant

• Current Assignee: Ethicon Endo-Surgery, Inc. (Johnson & Johnson)
• Original Assignee: Ethicon Endo-Surgery, Inc. (Johnson & Johnson)
• Inventors: Donofrio, William T., Wiener, Eitan T.
• Granted Patent: US 6,679,899 B2
• Time in Patent Office: Days
• US Class Current: 606/169
• CPC Class Codes: A61B 17/320068 using mechanical vibrations, e.g. ultrasonic A61B17/22012 takes precedence; dental tooth drilling devices operated by vibration A61C3/03; removing intra-ocular material using mechanical vibrations A61F9/00745
• CPC Class Codes: A61B 2017/00026 Conductivity or impedance, e.g. of tissue
• CPC Class Codes: A61B 2017/0003 of parts of the instruments
• CPC Class Codes: A61B 2017/00119 alarm; indicating an abnormal situation
• CPC Class Codes: A61B 2017/00137 Details of operation mode
• CPC Class Codes: A61B 2017/320069 for ablating tissue
• CPC Class Codes: A61B 2017/320071 with articulating means for working tip
• CPC Class Codes: A61B 2017/320089 node location

Abstract

A method for detecting transverse mode vibrations in an ultrasonic hand piece/blade is achieved by monitoring the power delivered to the hand piece/blade to determine whether it increases as expected when power levels applied to the hand piece/blade are changed. While the blade is being held in midair, the power delivered to the hand piece/blade and /or the impedance of the hand piece/blade is measured at a first power level. Using the value obtained at the first power level, the expected power at a second power level is calculated and used to set a pass/fail threshold level for an actual measured power. Alternatively, the threshold is set for the impedance is set. Next, the actual power delivered to the hand piece/blade and/or the impedance of the hand piece/blade is measured at a level 5 power setting. A determination is made whether the hand piece/blade exhibits transverse mode behavior based on whether the actual measured power exceeds the established pass/fail threshold level. If this is the case, operation of the generator is inhibited, a “Transverse Mode Vibrations Present in Hand Piece/Blade” error code is stored in the generator, and a “Bad Hand Piece” message is displayed on a liquid crystal display on the generator. In addition, a method for detecting transverse mode vibration in an ultrasonic hand piece/blade is achieved by monitoring power delivered to the hand piece/blade to determine if the an extraordinary power increase occurs as the drive frequency is shifted downward and/or upward from a primary intended resonance operating frequency.

Claims

1. A method for detecting transverse vibrations in an ultrasonic hand piece, comprising the steps of:

applying a drive signal to an ultrasonic hand piece using an ultrasonic generator;

measuring power delivered to the hand piece/blade at a first power level while the hand piece/blade is held in midair;

calculating an expected power using the first power level;

setting a pass/fail threshold level for an actual measured power based on the expected power;

measuring the actual power delivered to the hand piece/blade;

comparing the measured actual power to the pass/fail threshold;

if the measured actual power is less than the pass/fail threshold, displaying a first message on a liquid crystal display of the generator; and

if the measured actual power is greater than the pass/fail threshold, displaying a second message on a liquid crystal display of the generator.

2. The method of claim 1, wherein the first message is a “

Hand Piece/Blade Passed”

message.

3. The method of claim 1, wherein the first power level is approximately 100 ma RMS.

4. The method of claim 3, wherein said calculating step comprises the step of:

calculating the expected power for a level five setting.

5. The method of claim 1, wherein said step of displaying a second message comprises the step of:

storing a “

Transverse Mode Vibrations Present in Hand Piece/Blade”

error code in the generator; and

displaying a “

Bad Hand Piece”

message on the liquid crystal display of the generator.

6. The method of claim 1, wherein the drive signal has a frequency of approximately 20 Khz to 70 KHz.

7. The method of claim 1, wherein the pass/fail threshold is approximately 10 percent of the expected power.

8. The method of claim 3, wherein the level 5 setting is approximately 425 ma RMS.

9. A method for detecting transverse vibrations in an ultrasonic hand piece, comprising the steps of:

applying a drive signal at a primary resonance frequency to an ultrasonic hand piece using an ultrasonic generator;

measuring impedance of the hand piece at the primary resonance frequency;

shifting the primary resonance frequency of the drive signal;

measuring the impedance of the hand piece at the shifted resonance frequency;

comparing the measured impedance at the primary resonance frequency to the impedance of the hand piece at the shifted resonance frequency; and

if the measured impedance is greater than a predetermined threshold, displaying a message on a liquid crystal display of the generator.

10. The method of claim 9, wherein the said shifting step comprises the step of:

shifting the drive frequency downward by a first frequency.

11. The method of claim 10, wherein the first frequency is approximately 200 Hz.

12. The method of claim 9, wherein the primary resonance is approximately 55 kHz.

13. The method of claim 9, wherein said comparing step comprises the step of:

determining whether the impedance of the hand piece at the primary resonance is no more than twenty percent lower than the impedance of the hand piece at the shifted resonance frequency; and

initiating an alarm to indicate a transverse malfunction exists, if the impedance of the hand piece at the primary resonance is more than twenty percent lower than the impedance of the hand piece at the shifted resonance frequency.

14. The method of claim 9, further comprising the step of:

shifting the drive frequency upward.

15. The method of claim 14, wherein said shifting step comprises the step of:

shifting the drive frequency a predetermined frequency above the primary resonance; and

measuring the impedance of the hand piece at the predetermined frequency.

16. The method of claim 14, wherein the predetermined frequency is approximately 200 Hz.

17. The method of claim 15, further comprising the step of:

comparing the measured impedance at the primary frequency to the measured impedance at the predetermined frequency above the primary frequency.

18. The method of claim 17, wherein said comparing step comprises the step of:

determining whether the impedance of the hand piece at the primary resonance is no more than twenty percent lower than the impedance of the hand piece at the predetermined frequency above the primary frequency.

19. The method of claim 18, wherein the predetermined frequency is approximately 200 Hz.

20. The method of claim 18, further comprising the step of:

initiating a pause, if the impedance the hand piece at the primary resonance is no more than twenty percent lower than the impedance of the hand piece at the predetermined frequency above the primary frequency; and

returning to the step of applying the drive signal at the primary resonance frequency to the ultrasonic hand piece using the ultrasonic generator.

21. The method of claim 20, wherein the pause is at least 10 seconds.

22. The method of claim 18, further comprising the step of:

returning to said step of initiating an alarm, if the impedance of the hand piece at the primary resonance is more than twenty percent lower than the impedance of the hand piece at the predetermined frequency above the primary frequency.

23. The method of claim 9, wherein the drive signal has a constant current level.

25. The method of claim 24, wherein the message is a “

Hand Piece/Blade Contains Transverse Mode Vibrations”

message.

27. The method of claim 26, wherein the minimum drive current level is approximately 100 ma RMS and the maximum drive current level is approximately 425 ma RMS.

28. The method of claim 24, wherein the response curves are at least one of a Power-Delivered vs. Drive Current Level curve and a Hand Piece/Blade impedance vs. Drive Current level curve.

29. The method of claim 24, wherein the extrapolation comprises the step of:

checking the generated response curves to determine whether any curve represents at least one of a straight line and a relationship which is quadratic.

24. A method for detecting transverse vibrations in an ultrasonic hand piece, comprising the steps of:

sweeping a drive signal having a voltage and current applied to an ultrasonic hand piece/blade using an ultrasonic generator;

monitoring and storing voltages and currents applied to the hand piece/blade in non-volatile memory located in the ultrasonic generator;

calculating power delivered to the hand piece based on the stored voltages and stored currents;

generating response curves based on the stored voltages and stored currents;

performing an extrapolation using the response curve to determine whether the hand piece/blade exhibits transverse modes;

if the hand piece/blade exhibits transverse modes, displaying a message on a liquid crystal display of the generator.

26. The method of claims 24, wherein said applying step comprises the step of:

applying the drive signal from a minimum drive current level to a maximum drive current level.

30. A method for detecting transverse vibrations in an ultrasonic hand piece, comprising the steps of:

applying a drive signal to an ultrasonic hand piece using an ultrasonic generator;

measuring impedance of the hand piece/blade at a first power level while the hand piece/blade is held in midair;

calculating an expected impedance at a second power level using the first power level;

setting a pass/fail threshold for an increase in impedance of the hand piece/blade based on the calculated expected impedance;

measuring the impedance of the hand piece/blade at the second power level;

comparing the measured impedance at the second power level to the pass/fail threshold;

if the measured impedance of the hand piece/blade is less than the pass/fail threshold, displaying a first message on a liquid crystal display of the generator; and

if the measured impedance of the hand piece/blade is greater than the pass/fail threshold, displaying a second message on a liquid crystal display of the generator.

31. The method of claim 30, wherein the first message is a “

Hand Piece/Blade Passed”

message.

32. The method of claim 30, wherein the first power level is approximately 100 ma RMS.

33. The method of claim 32, wherein said calculating step comprises the step of:

calculating the expected impedance for a level five power setting.

34. The method of claim 30, wherein said step of displaying a second message comprises the step of:

storing a “

Transverse Mode Vibrations Present in Hand Piece/Blade”

error code in the generator; and

displaying a “

Bad Hand Piece”

message on the liquid crystal display of the generator.

35. The method of claim 30, wherein the drive signal has a frequency of approximately 20 Khz to 70 KHz.

36. The method of claim 30, wherein the pass/fail threshold is approximately 10 percent of the expected impedance.

37. The method of claim 32, wherein the level 5 setting is approximately 425 ma RMS.