Electrosurgery Devices

There are two main groups of procedures - electrocautery and electrosurgery, which uses high frequency alternating current (HFAC). Electrocautery uses electrical current to heat a metal instrument which is applied to target tissue in order to destroy it. Today, it is rarely performed. In this techniquethe patient is not exposed to the current, which is only used to heat the tool tip.

This group includes Shaw scalpel (low frequency alternating current, LFAC) and battery-powered portable coagulators (direct current, DC).

The second, much more complex group comprises of devices using the HFAC transmission. They are used widely in a variety of electrosurgical procedures, and their performance depends onthe characteristics and intensity of the current. Damped AC is chiefly used for tissue coagulation whereas sine wave current is better for tissue cutting.

Numerous devices use current of complex impulse characteristics, which enables both the coagulation and cutting (e.g. the so-called Bovie waves). The current can be brought into the tissue by means of an independent single electrode (monoterminal), a single electrode (monopolar) which requires a supplementary indifferent electrode to operate or by two electrodes placed on the forceps tines (bipolar electrodes). In the case of the indifferent electrode, which is typically placed on the body part opposite to the surgical site, electrical current passes from the tip of the probe through patient to the indifferent electrode, whereas with the bipolar electrodes (the so-called bicoagulation) –it runs through a small portion of the tissue grasped between the tines of the forceps. There are four basic electrosurgery procedures: electrosection, electrocoagulation, electrodessication and electrofulguration. Electrosection is carried out by means of the needle or blade electrodes with high voltage, high frequency current, which causes only a slight damage to the surrounding tissue. Coagulation is performed with bipolar (forceps) or unipolar electrodes, using high currents and slightly lower voltage (0.2A - 0.7A below 2000V).

The intradermal blood vessels are coagulated with very fine (a fraction of a millimetre in diameter) needle electrodes. The electrodes used for hair follicle coagulation are additionally teflon-coated over the entire length except for the tip. Fine structures within the dermis (hair follicles, blood vessels) are also destroyed by means of the so-called electrolysis, which is a gentle coagulation mode (employing low voltage, low amperage AC) making use of a destructive influence of both thecurrent and temperature. During classic electrolysis a patient holds the indifferent electrode in his hand and the effect is producedslowly – after several seconds at the earliest. Electrodessication (drying, burning out) usesspherical or needle monopolar electrodeswith the amperage of 0.5-0.75A and a voltage of approx. 2000V. Electrofulgurationis a non-contact method in which a monopolar electrode of a 0.5-0.75 Acurrent and a voltage exceeding 2000V does not touch the skin directly but produces electric sparks (arch) that affect the tissue. This causes tissue carbonisation which prevents further thermal damage to the underlying dermis, resulting in superficial defects (down to the papillary layer) which heal well.

The latest generation is composed of the devices using the electromagnetic radio frequency waves (the so-called radiofrequency). The energy delivered to the tissues in this way is used for electrosection or coagulation with less collateral tissue damage as compared to conventional electrosurgical devices. This group also includes a device for the so-called cold ablation, i.e. Coblation® or Thermage®, used for gentle revitalisation or resurfacing. There are no contraindications to usingthe monopolar electrocautery devices in patients with cardiac pacemakersand bipolar coagulation forceps are also relatively safe for use since the current flow is restricted to a small area between two electrodes on the arms of the forceps. In contrast, special attention must be paid when using devices with an indifferent electrode which pass the current through the body. If their use is necessary,the indifferent electrode shall be placed as far from the heart as possible, and the surgeon should use short, few-second pulses and monitor the ECG during the procedure.