Electrosurgical Generator With Adaptive Power Control

Abstract

An electrosurgical generator has an output power control system that causes the impedance of tissue to rise and fall in a cyclic pattern until the tissue is desiccated. The advantage of the power control system is that thermal spread and charring are reduced. In addition, the power control system offers improved performance for electrosurgical vessel sealing and tissue welding. The output power is applied cyclically by a control system with tissue impedance feedback. The impedance of the tissue follows the cyclic pattern of the output power several times, depending on the state of the tissue, until the tissue becomes fully desiccated. High power is applied to cause the tissue to reach a high impedance, and then the power is reduced to allow the impedance to fall. Thermal energy is allowed to dissipate during the low power cycle. The control system is adaptive to tissue in the sense that output power is modulated in response to the impedance of the tissue.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 10 / 434,019, filed on May 8, 2003, which is a reissue of U.S. patent application Ser. No. 09 / 209,323, now U.S. Pat. No. 6,228,080, filed on Dec. 11, 1998, which is a continuation of U.S. patent application Ser. No. 08 / 838,548, filed on Apr. 9, 1997, now U.S. Pat. No. 6,033,399, the contents of which are incorporated herein by reference.BACKGROUND[0002]1. Field of the Invention[0003]The present invention relates to an electrosurgical generator with an adaptive power control, and more particularly to an electrosurgical generator that controls the output power in a manner that causes impedance of tissue to rise and fall cyclically until the tissue is completely desiccated.[0004]2. Background of the Disclosure[0005]Electrosurgical generators are used by surgeons to cut and coagulate tissue of a patient. High frequency electrical power is produced by the electrosurgical gene...

AI Technical Summary

Problems solved by technology

One of the problems associated with electrosurgical desiccation is undesirable tissue damage due to thermal effects.

Healthy tissue adjacent to the operative site can become thermally damaged if too much heat is allowed to build up at the operative site.

The heat may conduct to the adjacent tissue and cause a large region of tissue necrosis.

The problem of thermal spread becomes important when electrosurgical tools are used in close proximity to delicate anatomical structures.

Another problem that is associated with electrosurgical desiccation is a buildup of eschar on the surgical tool, Eschar is a deposit on an electrosurgical tool that is created from tissue that is desiccated and then charred by heat.

The surgical tools win often lose effectiveness when they are coated with eschar.

The Bergdahl article also reported that it was not possible to coagulate safely arteries with a diameter larger than 2 to 2.5 millimeters.

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