Electrosurgical medical system and method

• US 20090088737A1
• Filed: 08/27/2008
• Published: 04/02/2009
• Est. Priority Date: 12/28/2000
• Status: Active Grant

• Current Assignee: Senorx Incorporated (Becton, Dickinson & Co)
• Original Assignee: Senorx Incorporated (Becton, Dickinson & Co)
• Inventors: Daw, Derek, Dabney, James Huntington
• Granted Patent: US 8,882,760 B2
• Time in Patent Office: Days
• US Class Current: 606/33
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/1402 Probes for open surgery
• CPC Class Codes: A61B 18/18 by applying electromagnetic radiation, e.g. microwaves radiation therapy A61N5/00
• CPC Class Codes: A61B 2018/00601 Cutting
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00726 Duty cycle
• CPC Class Codes: A61B 2018/00755 Resistance or impedance
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/00946 slidable
• CPC Class Codes: A61B 2018/1286 having a specific transformer

Abstract

A medical device system and method provide an RF electrosurgical generator coupled to an electrosurgical electrode via a patient box disposed in close proximity to the patient. An RF signal is delivered from the generator to the patient box where signal power is increased and the RF signal delivered to the electrosurgical electrode. The patient box is coupled to the electrosurgical electrode by a short cable capable of carrying an HV, high frequency 5 MHz signal without leakage. An electrical characteristic associated with the electrosurgical electrode is monitored and a desired RF power output and duty cycle maintained by adjusting DC input voltage applied to an RF amplifier, responsive to the monitoring. The system determines when the electrosurgical cutting electrode has started cutting and switches from a start mode to a run mode having a different RF duty cycle and a reduced RF power output controlled by a servo system.

Claims

1. A method for delivering RF power from an electrosurgical generator to an electrosurgical electrode being used on a patient to cut tissue, said method comprising:

providing the RF electrosurgical generator in a generator housing spaced from the patient with the electrosurgical generator having a first RF power level and a second RF power level greater than the first RF power level and a patient box in a patient box housing, said patient box housing disposed in closer proximity to said patient than said generator housing and said patient box coupled to said electrosurgical electrode by a cable not greater than 2 meters long;

delivering an RF signal with the first RF power level from said electrosurgical generator to the electrosurgical electrode coupled to said patient box;

increasing RF power of said RF signal from the first power level to the second power level from the electrosurgical generator to the electrosurgical electrode coupled said patient box; and

delivering said RF signal with second power level to said electrosurgical electrode as an RF output.

2. The method as in claim 1, wherein said RF signal with the second power level has a frequency of about 5 MHz.

3. The method as in claim 1, wherein said RF output includes a power of about 1200 Watts and said electrosurgical generator is disposed more that 10 meters from said patient.

4. The method as in claim 1, wherein said Increasing RF power of said RF signal to the second power level takes place using a transformer of said patient box.

5. The method as in claim 1, further comprising detecting a leakage current by inducing a test signal in said patient box by directing said RF signal through an RF transformer in said patient box, coupling a series of two capacitors between ground and a center tap of a winding in said RF transformer, and inducing said test signal onto RF output leads of said patient box by passing said RF signal through a common mode transformer, said test signal having a frequency of about 500 KHz.

6-42. -42. (canceled)

43. A medical device comprising:

an electrosurgical generator in a generator housing spaced from a patient and having a first RF power level;

a patient box in a patient box housing, said patient box housing disposed in closer proximity to the patient than said generator housing;

an electrosurgical electrode for operating on the patient which is coupled to said patient box by a cable not greater than 2 meters long;

a first transmitting member for delivering an RF signal with a first RF power level from said electrosurgical generator to said patient box;

means for increasing RF power of said first RF signal from the first RF power level to the second RF power level in said patient box; and

a second transmitting member for delivering said RF signal with the first RF power level and the second RF power lever to said electrosurgical electrode.

44. A system for controlling an electrosurgical electrode of a medical device comprising:

an RF generator coupled to an electrosurgical electrode, said RF generator including an RF amplifier and configured to generate a first RF power level and a second RF power level greater than the first RF power level;

transmitting means for delivering an RF signal at a first RF power level and a second RF power level from said RF generator to said electrosurgical electrode;

a sensor for monitoring an electrical characteristic associated with said electrosurgical electrode; and

a controller for maintaining a desired RF power output and a desired RF duty cycle by adjusting DC input voltage applied to an output stage of said RF amplifier based on said monitoring.

45. The system as in claim 44, further comprising

a patient box coupled between said RF generator and said electrosurgical electrode, said patient box and said electrosurgical generator disposed in separate housings;

the transmitting means delivering an RF signal from said RF electrosurgical generator to said electrosurgical electrode by way of said patent box;

a common mode choke in said patient box, said common mode choke including an output winding and a return winding, each wound about a ferrite core, said output winding and said return winding spaced apart and in parallel to maintain a desired impedance, said output winding comprising a wire carrying said RF signal and said return winding comprising a duality of intertwined wires, each winding including adjacent ribs spaced apart; and

means for directing a common mode signal from said RF signal to said common mode choke thereby blocking said common mode signal while allowing said output signal to be applied substantially unaltered to a patient.

48. The system of claim 45 wherein the transmitting means includes a balanced and symmetrical shielded transmission line coupling said electrosurgical generator to a transformer of said patient box.

46-47. -47. (canceled)