Electrosurgical units are medical devices to heat the tissues by using high frequency. They are used as a means to cut, coagulate, desiccate, or fulgurate tissue.
These modes are determined according to power applied.
In cutting mode electrodes touch the tissue, and high power density is applied to vaporize its water content. Since water vapor is not conductive under normal circumstances, electric current cannot flow through the vapor layer. Energy delivery beyond the vaporization threshold can continue if sufficiently high voltage is applied.
Read More
Coagulation is performed using waveforms with lower average power, generating heat insufficient for explosive vaporization. This enables the formation of thermal coagulum instead of vaporization.
Electrosurgical desiccation occurs when the electrode touches the tissue open to air, and the amount of generated heat is lower than that required for cutting. The tissue surface and some of the tissue more deep to the probe dries out and forms a coagulum. This technique may be used for treating nodules under the skin and creates minimal damage to the skin surface.
In fulguration mode, the electrode is held away from the tissue, so that when the air gap between the electrode and the tissue is ionized, an electric arc discharge develops. So that the burning of the tissue is more superficial, because the current is spread over the tissue area larger than the tip of the electrode. Under these conditions, superficial skin charring or carbonization is seen over a wider area than when operating in contact with the probe, and this technique is therefore used for very superficial or protrusive lesions such as skin tags. Ionization of an air gap requires voltage in the kV range.
Electrosurgical units are commonly used in general surgery, gastroenterology, dermatology etc.
How does an electrosurgical unit work ?
Electrical energy which is produced by the electrosurgical unit is converted to the high frequency current. This high frequency current is transmitted to a spot electrode by a cable and handle. Concentrated energy at the electrode is balanced through the patients and electrosurgical effect exists. The importance of the working high frequency interval is that muscles and nerves are not affected. Localized heating allow for the precise process reducing the risk of the bleeding.
What is the advantage of electrosurgery ?
Electrosurgical units minimize bleeding and provide high precision in cutting and coagulation processes.
What is the difference between electrosurgery & electrocautery ?
Electrosurgical units are powered to be used in both cutting and coagulation processes. Electrocautery units are able to perform only the coagulate process. This difference exists because of the working principles of the units. Usually this differentiation is not well defined in daily life and definitions of the units are mentioned interchangeably.
What is monopolar and bipolar in the use of electrosurgical units?
Monopolar and bipolar terms define the traveling way of the current which is induced by the electrosurgical unit. In the monopolar process the patient is attached to the dispersive electrode. It is a metal plate or flexible metalized plastic pad. Activated electrode is the pointed or blade shaped electrode which is used by the surgeon. The electric current flows between these electrodes through the patient body, when the surgeon initiates the process.
In a bipolar unit, current travels between the active electrode and device. Dispersive electrodes are not required. Current travels in a short way and don’t need to take a long way through the patient’s body. Bipolar units provide advantage if the patient has implanted lifesaving devices such as a pacemaker.Monopolar current may affect these kinds of lifesaving devices adversely.
Safety precautions in using electrosurgical units:
Electrosurgical unit should be used carefully. Users should read the operating manual very carefully and follow the directives of the manufacturer. Working principle of the electrosurgical units should be understood clearly to avoid any inconvenient situation. Protection of the patient and end user health as well are important.
Severe burns can occur if the contact with the return electrode is insufficient, or when a patient comes into contact with metal objects serving as an unintended leakage path to Earth/Ground.
To prevent unintended burns, the skin is cleaned and a conductive gel is used to enhance the contact with the return electrode. Proper electrical grounding practices must be followed in the electrical wiring of the building.
If there is any metal in the body of the patient, the return electrode is placed on the opposite side of the body from the metal and be placed between the metal and the operation site.
The use of the bipolar option does not require the placement of a return electrode because the current only passes between tines of the forceps or other bipolar output device.
Electrosurgery should only be performed by a physician who has received specific training in this field and who is familiar with the techniques used to prevent burns.
