Method for detecting blade breakage using rate and/or impedance information

• US 6,633,234 B2
• Filed: 05/24/2001
• Issued: 10/14/2003
• Est. Priority Date: 10/20/2000
• Status: Expired due to Term

• Current Assignee: Ethicon Endo-Surgery, Inc. (Johnson & Johnson)
• Original Assignee: Ethicon Endo-Surgery, Inc. (Johnson & Johnson)
• Inventors: Stulen, Foster B., Wiener, Eitan T., Friedman, Allan L.
• Primary Examiner(s): POPE, DARYL C
• Application Number:
  US09/864,089
• Publication Number:
  US 20020049427A1
• Time in Patent Office: 873 Days
• Field of Search: 340/680, 340/679, 340/683, 340/506, 340/3.1, 702/106, 702/66, 702/107, 702/171, 702/65, 702/64, 702/74, 702/75, 702/81, 702/82, 606/169, 606/41
• US Class Current: 340/680
• 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 2017/00119 alarm; indicating an abnormal situation
• CPC Class Codes: A61B 2017/00199 with a console, e.g. a control panel with a display
• CPC Class Codes: A61B 2017/00973 pedal-operated
• 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
• CPC Class Codes: A61B 90/98 using electromagnetic means, e.g. transponders

Abstract

Failures associate with bad hand pieces and blade failures in an ultrasonic surgical system are distinguished by monitoring the rate of change of the resonance frequency and the rate of change of the resonance impedance of the hand piece/blade as the drive frequency is changed. As the system reaches resonance, the control system locks onto the resonance frequency. When a loss of lock occurs with no recovery, the rate of change of the frequency and rate of change of the impedance are compared to obtain the fastest rate of change which is stored in non-volatile memory of the ultrasonic generator. If the rates of change are higher than normal rates of change due to temperature changes with the longest blades, a “Bad Blade” message is displayed on an LCD.

Claims

1. A method for distinguishing between bad hand pieces and blade failures in an ultrasonic surgical system, comprising the steps of:

applying a drive signal to an ultrasonic hand piece/blade at a predetermined drive frequency;

monitoring and storing a rate of change of a resonance frequency and a rate of change of a resonance impedance of the hand piece/blade as the drive frequency is changed in memory of the generator;

performing a diagnostic self test in an ultrasonic generator located in the ultrasonic surgical system;

monitoring the ultrasonic generator in the ultrasonic surgical system to determine whether lock is present;

if lock is not present, retrieving the rate of change of the resonance frequency and the rate of change of the resonance impedance from memory of the generator;

comparing the rate of change of the resonance frequency and the rate of change of the resonance impedance to obtain a fastest rate of change which is stored in the memory of the generator; and

if the rates of change are higher than normal rates of change due to temperature changes associated with longer blades, displaying a message on a liquid crystal display of the generator.

2. The method of claims 1, wherein the step of applying the drive signal comprises exciting the hand piece/blade with an ultrasonic signal at the predetermined drive frequency.

3. The method of claim 2, wherein the predetermined drive frequency is in a range of 50 kHz to 56 kHz.

4. The method of claim 1, wherein the step of monitoring the rate of change of the resonance frequency and the rate of change of the resonance impedance is performed continuously at start up.

5. The method of claim 1, wherein, if the diagnostic self test fails, all tests are terminated.

6. The method of claim 1, wherein the step of monitoring the ultrasonic generator is performed during use of the hand piece/blade.

7. The method of claim 6, wherein use of the hand piece/blade comprises at least one of running the hand piece/blade in mid-air, cutting tissue, cauterizing tissue and coagulating tissue.

8. The method of claim 1, wherein the step of displaying the message comprises the steps of:

displaying a “

Bad Blade”

message on the liquid crystal display, if the rates of change are higher than the normal rates of change due to the temperature changes associated with the longer blades; and

displaying a “

Bad Hand Piece”

message on the liquid crystal display, if the fastest rates of change are lower than the normally expected rates of change due to the temperature changes associated with the blades having the longest physical length and the generator passed the diagnostic self test.

9. The method of claim 8, wherein the normally expected rates of change are constant values which are stored in the memory of the generator.