Power supply and methods for limiting power in electrosurgery

• US 6,296,636 B1
• Filed: 07/21/1999
• Issued: 10/02/2001
• Est. Priority Date: 05/10/1994
• Status: Expired due to Fees

• Current Assignee: ArthroCare Corporation (Smith & Nephew PLC)
• Original Assignee: ArthroCare Corporation (Smith & Nephew PLC)
• Inventors: Eggers, Philip E., Thapliyal, Hira V., Cheng, Andrew M. L.
• Primary Examiner(s): COHEN, LEE S
• Application Number:
  US09/357,774
• Time in Patent Office: 804 Days
• Field of Search: 606/32, 606/34, 606/37-42, 606/46, 606/49, 607/99, 607/105, 607/113, 604/114
• US Class Current: 606/32
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/1402 Probes for open surgery
• CPC Class Codes: A61B 18/148 having a short, rigid shaft for accessing the inner body transcutaneously, e.g. for neurosurgery or arthroscopy
• CPC Class Codes: A61B 18/1482 having a long rigid shaft for accessing the inner body transcutaneously in minimal invasive surgery, e.g. laparoscopy
• CPC Class Codes: A61B 18/1485 having a short rigid shaft for accessing the inner body through natural openings
• CPC Class Codes: A61B 18/149 bow shaped or with rotatable body at cantilever end, e.g. for resectoscopes, or coagulating rollers
• CPC Class Codes: A61B 18/1492 having a flexible, catheter-like structure, e.g. for heart ablation A61B18/1477 takes precedence
• CPC Class Codes: A61B 2017/00026 Conductivity or impedance, e.g. of tissue
• CPC Class Codes: A61B 2017/00084 Temperature
• CPC Class Codes: A61B 2017/00101 using an array of thermosensors
• CPC Class Codes: A61B 2017/00247 Making holes in the wall of the heart, e.g. laser Myocardial revascularization
• CPC Class Codes: A61B 2018/00029 open
• CPC Class Codes: A61B 2018/00083 low, i.e. electrically insulating
• CPC Class Codes: A61B 2018/00119 with metal oxide nitride
• CPC Class Codes: A61B 2018/0016 Energy applicators arranged in a two- or three dimensional array
• CPC Class Codes: A61B 2018/00178 Electrical connectors
• CPC Class Codes: A61B 2018/00327 Ear, nose or throat
• CPC Class Codes: A61B 2018/00392 Transmyocardial revascularisation
• CPC Class Codes: A61B 2018/00505 Urinary tract
• CPC Class Codes: A61B 2018/00577 Ablation
• CPC Class Codes: A61B 2018/00583 : Coblation, i.e. ablation using a cold plasma
• CPC Class Codes: A61B 2018/00666 : using a threshold value
• CPC Class Codes: A61B 2018/00678 : upper
• CPC Class Codes: A61B 2018/00702 : Power or energy
• CPC Class Codes: A61B 2018/0072 : Current
• CPC Class Codes: A61B 2018/00726 : Duty cycle
• CPC Class Codes: A61B 2018/00779 : Power or energy
• CPC Class Codes: A61B 2018/00791 : Temperature
• CPC Class Codes: A61B 2018/00827 : Current
• CPC Class Codes: A61B 2018/00875 : Resistance or impedance
• CPC Class Codes: A61B 2018/00982 : combined with or comprising means for visual or photographic inspections inside the body, e.g. endoscopes
• CPC Class Codes: A61B 2018/1213 : creating an arc
• CPC Class Codes: A61B 2018/124 : switching the output to different electrodes, e.g. sequentially
• CPC Class Codes: A61B 2018/1253 : monopolar
• CPC Class Codes: A61B 2018/126 : bipolar
• CPC Class Codes: A61B 2018/1273 : including multiple generators in one device
• CPC Class Codes: A61B 2018/1467 : using more than two electrodes on a single probe
• CPC Class Codes: A61B 2018/1472 : for use with liquid electrolyte, e.g. virtual electrodes
• CPC Class Codes: A61B 2018/162 : located on the probe body
• CPC Class Codes: A61B 2018/165 : Multiple indifferent electrodes
• CPC Class Codes: A61B 2218/002 : Irrigation
• CPC Class Codes: A61B 2218/007 : Aspiration
• CPC Class Codes: A61F 2/2493 : Transmyocardial revascularisation [TMR] devices
• CPC Class Codes: A61M 3/0283 : with at least two inner passageways, a first one for irrigating and a second for evacuating suction-irrigation systems A61M1/77; aspiration tips with fluid supply means A61M1/85; for negative pressure wound therapy A61M1/92

Abstract

A high frequency power supply for applying electrical energy to a target site on or within a patient'"'"'s body includes an electrical output driver, an output current sensor detecting the current output from the driver, and a power limiting device coupled to the current sensor during normal conditions, the power limiting device operates on a continuous basis. When current output exceeds a predetermined threshold level, the power limiting device is adapted to reduce power on the output driver to a standby mode. The power limiting device operates on a periodic detection or duty cycle when in the standby mode. The power limiting device switches into the stand-by mode to prevent excessive power drains. The power supply operates at a low power, pulsatile manner when an attached probe is in conductive or isotonic fluid but is not engaging body tissue or near a high impedance source. In this pulsatile mode, the power supply operates in a cyclical manner, typically at a predetermined duty cycle.

Claims

1. A method for applying electrical energy to a target site on or within a patient'"'"'s body, the method comprising:

introducing an electrically conductive fluid to a target site on or with a patient'"'"'s body;

positioning an electrode terminal within the electrically conductive fluid in contact with or close proximity to tissue at the target site on or within a patient'"'"'s body, the electrode terminal being coupled to a high frequency power supply;

positioning a return electrode within the electrically conductive fluid such that the return electrode is not in contact with the tissue;

applying high frequency voltage to the electrode terminal to at least modify the tissue; and

detecting the current output from the power supply; and

reducing power applied to the electrode terminal when the current output exceeds a predetermined threshold current.

2. The method of claim 1 further comprising interrupting current output when the electrode terminal is brought adjacent to a metal object within the patient'"'"'s body and introducing a predetermined delay after power is disrupted.

3. The method of claim 1 wherein the detecting step further comprises:

conditioning a signal from a current sensor; and

comparing a value of said signal to a value of a predetermined threshold current.

4. A method of claim 1 wherein the predetermined threshold current is about 1.0 to 3.0 amperes for spark limiting.

5. A method of claim 1 further comprising positioning the electrode terminal within the synovial sac of the knee to remove soft tissue.

6. A method of claim 1 further comprising passing the electrode terminal through the synovial sac of the knee to remove soft tissue around a fastener.