Electrosurgical pencil with drag sensing capability

• US 7,621,909 B2
• Filed: 06/12/2008
• Issued: 11/24/2009
• Est. Priority Date: 07/25/2002
• Status: Expired due to Fees

• Current Assignee: Covidien AG (Medtronic Plc)
• Original Assignee: Covidien AG (Medtronic Plc)
• Inventors: Podhajsky, Ronald J., Reschke, Arlan J., Buchman, Thomas L. II
• Primary Examiner(s): Cohen; Lee S
• Application Number:
  US12/137,717
• Publication Number:
  US 20080243118A1
• Time in Patent Office: 530 Days
• Field of Search: 606/38, 606/42, 606/45, 606/49
• US Class Current: 606/42
• CPC Class Codes: A61B 18/1402 Probes for open surgery
• CPC Class Codes: A61B 2018/00077 high, i.e. electrically conducting
• CPC Class Codes: A61B 2018/00107 Coatings on the energy applicator
• CPC Class Codes: A61B 2018/00148 with metal
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/1412 Blade
• CPC Class Codes: A61B 2090/064 for measuring force, pressure or mechanical tension

Abstract

An electrosurgical pencil configured and adapted to support an electrocautery blade. A strain gauge is affixed to the proximal end of the electrocautery blade and measures the displacement of the blade as a result of resistance and drag acting on the blade. The electrosurgical pencil also includes a meter electrically connected to the strain gauge for monitoring either a change in voltage, a change in electrical current or a change in optical wavelength. The amount of blade displacement as measured by the strain gauge is available for display to the surgeon and/or as sensory input for a control circuit in the electrosurgical generator that modulates the generator output waveform. The electrosurgical pencil further includes a control circuit electrically coupled between the electrocautery blade and the electrosurgical generator. The control circuit is configured and adapted to control power supplied to electrocautery blade based on the displacement measured by the strain gauge.

Claims

1. An electrosurgical instrument adapted for selective connection to an electrosurgical generator, the electrosurgical instrument comprising:

a housing;

an electrocautery blade supported within the housing and extending partially therefrom, the blade adapted to connect to the electrosurgical generator which provides electrosurgical energy to the blade;

an activation switch adapted for selective connection to the generator which permits selective activation of the electrocautery blade;

a strain gauge in communication with the electrocautery blade for measuring a displacement of the electrocautery blade, the strain gauge configured to produce an electrical signal in the form of a measured drag signal; and

a drag evaluation circuit operatively connected to the strain gauge, wherein the drag evaluation circuit receives the measured drag signal from the strain gauge, and compares said measured drag signal against an initial preset drag value, wherein the electrosurgical generator adjusts at least one parameter to compensate for at least one of an increase, a decrease and a non-change in displacement of the electrocautery blade,

wherein the drag evaluation circuit is in operative communication with a feedback correction circuit for transmitting an evaluation signal thereto,

wherein if the compared said measured drag signal is one of higher and lower than the initial preset drag value then the feedback correction circuit resets the initial preset drag value to a value that is one of higher and lower than said initial preset drag value.

2. The electrosurgical instrument according to claim 1, wherein the drag evaluation circuit receives a measured drag signal and at least one of evaluates and compares the measured drag signal against the preset drag value.

3. The electrosurgical instrument according to claim 1, wherein the feedback correction circuit is in operative communication with the electrosurgical generator and when the given drag signal is above the preset drag value the feedback correction circuit increases electrosurgical energy outputted to the electrocautery blade and resets the preset drag value.

4. The electrosurgical instrument according to claim 3, wherein when the given drag signal is below the preset drag value the feedback correction circuit decreases electrosurgical energy outputted to the electrocautery blade and resets the preset drag value.

5. The electrosurgical instrument according to claim 3, wherein the feedback circuit checks the preset drag value at least 100 times per second.

6. The etectrosurgical instrument according to claim 1, wherein the electrosurgical generator includes a cut-off control circuit for monitoring the amount of electrosurgical energy being delivered to the electrocautery blade such that a threshold value is not exceeded.