Over the last several decades, more and more surgeons are abandoning traditional open methods of gaining access to vital organs and body cavities in favor of endoscopes and endoscopic instruments that access organs through small puncture-like incisions. Endoscopic instruments are inserted into the patient through a cannula, or a port that has been made with a trocar. Typical sizes for cannulas range from about three millimeters to about twelve millimeters. Smaller cannulas are usually preferred, and this presents a design challenge to instrument manufacturers who must find ways to make surgical instruments that fit through the cannulas and operate in a safe and effective manner.
Devices for arresting blood loss and coagulating tissue are well known in the art. For example, several prior art instruments employ thermic coagulation (heated probes) to arrest bleeding. However, due to space limitations, surgeons can have difficultly manipulating an instrument to coagulate, desiccate, fulgurate and/or cut tissue. Other instruments direct high frequency electric current through the tissue to stop the bleeding. Eschar adherence may also be a problem with these instruments. In both types of instruments, the depth of the coagulation is difficult to control.
Using these instruments to treat certain more sensitive tissue sites may be impractical since the constant and/or direct emission of ionized gas/plasma at the tissue may cause unintended results. Moreover, simply controlling the pressure of the gas from the source may not be effective or yield a desired result.