High frequency electrosurgery

Introduction
Among surgical equipment the electrosurgical devices are probably the most commonly used and also most useful. High frequency electrosurgery is a surgical technique related to Diathermy, which is a clinical method that uses high frequency electromagnetic currents for clinical therapy and has surgical applications. Electrocauterization is a different concept from electrosurgery, but is still an important medical application of diathermy. The two are often mistakenly confused because of the use of the electrocoagulation (electrosurgical method). Electrosurgery uses alternating current to directly heat the tissue itself. Unlike electrocauterization that uses direct current to heat a probe to a glowing temperature to cauterize the tissue through heat conduction.

Biophysics in High Frequency Electrosurgery


Figure 1 - Applications of different current frequencies

Electrosurgery has been described as high-frequency electrical current passed through tissue to create a specific clinical effect. The frequency used must be sufficient to cross the tissues but without activating the muscles, such case would cause muscles contraction preventing the surgeon to work and it is likely to cause the patient's heart to stop. Electrical current in biological tissues is due to connectivity of ionic interstitial fluids. To have an electric current there must be an electric circuit, which is an uninterrupted pathways of flowing electrons.Transition between the electronic and ionic conduction is governed by electrochemical processes at the electrode–electrolyte interface. Ohm’s Law describes the actions of a given circuit:

V = I x R

Where I is the intensity of the current, V is the Voltage (force driving the current against the resistence) and R is the resistence of the circuit. -This unities are measured in volt, ampere and ohm respectively.- In electrosurgery, voltage is provided by a generator (which can be monopolar or bipolar – see instruments and it’s aplications) and current is delivered to the tissues through the electrode tip of the instrument. Resistance to the current is inherent to all human tissues, if the inherent resistence is higher, than the given voltage also needs to be higher for the current to pass. The current goes thro the patient’s body to a returnelectrode, which is connected to the generator, completing the circuit.

Monopolar Instrument
The monopolar instrument has three parts: the active electrode, the conductive adhesive grounding pad and the generator. The current leaves the generator and is conducted to the active electrode. Then the active electrode conducts it to the body. The conductive adhesive grounding pad is attached to the patient's body and will conduct the current back to the generator. The monopolar instrument doesn't work in a liquid medium, like blood, because this way the current is dispersed. For that reason, this instrument was enhanced with the incorporation of a argon beam, this way, when the gas becomes ionized by the energy of the electrosurgical device, it wipes away the blood. Since argon is a noble gas it makes possible for the current to arc, following the way of the gas column, creating a superficial coagulation, ideal for using in large surface areas.

Bipolar Instrument
The bipolar instrument has three parts aswell: the active electrode and the return electrode, which are located in a device similar to surgical forceps, and the generator. After leaving the generator the current goes to the active electrode (in one tip of the tweeser-like device), goes to the patient's body and comes back for the other tip of the device, to the return electrode. The return electrode leads the current back to the generator. This instrument was initially used for coagulation of tissue, but evolved to be used in complete fusion of intimal layers of tissue, like vascular structures. This creates the opportunity for the surgeon to seal vessels without suture, staples or traditional clips.

Applications of the method

 * Cut - to make an incision
 * Coagulate - which is a way for the surgeon to facilitate the formation of clots in blood, therefor stop the bleeding in some damaged blood vessels;
 * Dessicate - extraction of water of tissues or incisions;
 * Fulgration - method that aloows the surgeon to destroy tissue, like malignant tumor, hemangiomas or even warts:
 * Sealing - to fuse together layers of tissue (as referred above).

Advantages
Some studies say that this type of surgery allows less operating time and limited bleeding.

The low cost (comparing to laser surgery) is also evident, and also the less post-operative time for recovery.

This is a field in medicine which is always evolving, as emphasized by the following article: "Instead of the classic scalpel, surgeons can also operate with an electroscalpel. A significant advantage to this technique is that while a cut is being made, blood vessels are closed off and hemorrhaging eliminated. Now another advantage may be added as well: a German-Hungarian research team has developed a mass-spectrometry-based technique by which tissues can be analyzed during a surgical procedure."