Non-Plasma and Plasma Settings

Non-Plasma Settings

At the lower voltages, typically below about 65-125 volts root mean square (rms), the saline solution is merely activated by joule dissipation of the electrolyte ions moving in the solution in response to the imposed electric fields. This heated fluid can interact with nearby tissue. The tissue can also be affected directly by the electrical currents if the tissue is sufficiently electrically conducting (usually through the presence of naturally-occurring ions such as sodium, potassium, chloride, and the like). Blood vessels within the tissue may also be coagulated, thereby stopping their bleeding during the surgical procedure.

With Coblation^® products, coagulation occurs at a much lower temperature than with conventional electrocautery: it is obtained through a shrinkage of the vessel fibers, reducing the diameter of the lumen, and also through a coagulation of the proteins contained in the plasma (blood).

Plasma Settings

Coblation technology works by generating an electric field between a single or cluster of active electrodes located on the tip of a radiofrequency device and a return electrode located more proximally on the same bipolar device. Current flows through an electrically conductive solution, such as saline.

With Coblation settings, a voltage (150-350V) is introduced across the electrodes on a Wand. To learn more about this instrument and its use in Coblation technology, click here. This electrical field interacts with underlying fluid, such as saline, to excite electrolytes and molecules in the fluid and create a high-density energy field called plasma. The plasma field contains energized particles with sufficient energy to break soft tissue organic molecular bonds, thus producing conditions that are effective in dissolving tissue at relatively low temperatures.

The formation of a gas layer is an important process leading to the plasma-forming conditions. Gas formation at the electrode is the result of an electrochemical process at the surface of the electrodes. In addition, when the local joule reaction of the saline induced by the electric field and current density near the energized electrodes exceeds the temperature of vaporization of the fluid (e.g. water) and the rate at which the heat dissipates due to thermal conduction, localized vaporization can develop. As a very thick vapor layer forms (on the order of 100µm) and high impedance of the vapor layer as compared with the saline occurs, the electric field across this area, which is localized in thin regions around the electrode(s), increases dramatically (300V across 100µm is 30,000 V/cm), ionizing and fragmenting the water molecules in the vapor layer and forming the plasma field.