Electrosurgical Unit (Surgical diathermy machine)
Electrosurgical unit (ESU) is a device used for surgical cutting and coagulation of bleeding vessels through surgical diathermy. In surgical diathermy, a high frequency electric current (0.45 – 2 MHz) is used to produce heat to coagulate blood vessels, or to cut and at the same time seal the blood vessel.
The heating is regulated by a variable resistance and the resultant tissue effect is determined by the electrical waveform produced.
Electrosurgical units are of two types – Monopolar and Bipolar.
Monopolar Electrosurgical Unit
Monopolar units produce different waveforms used for several procedures including cutting, blending, desiccation, and fulguration. Using the pencil instrument, an active electrode is placed in the entry site and the current flows through the target tissue (causing tissue cut or hemostasis) to a return electrode and back to the generator.
Cutting is achieved using continuous low voltage waveform, while coagulation is a result of high voltage produced in bursts. It has a wide clinical acceptance due to its effectiveness.
Bipolar Electrosurgical Unit
Bipolar unit possesses a pair of forceps with two tips individually representing the active electrode and return electrode. In bipolar diathermy, the risk of patient burn is significantly reduced since it produces low energy output (1 to 20 watts VS 20 to 400 watts of monopolar), but is less versatile in clinical application.
Coagulation is achieved by closing the forceps around a piece of tissue using lower voltages compared to monopolar electrosurgical unit.
Bipolar surgical diathermy is more ideal for procedures involving small vessels that can easily be held within the circumference of the forceps tips – large blood vessels and bleeding areas should not be operated using bipolar diathermy.
Maintaining an Electrosurgical Unit
The most significant maintenance need for an electrosurgical unit is the electrical safety check carried out using an Electrical Safety Analyzer. Just like it’s counterpart class III device, an ESU requires regular cleaning, and preventive maintenance at least twice a year – check the plate electrodes, the leads, and the forceps tips.
Most other problem you will encounter is that of faulty leads which can be easily repaired. Check the forceps to ascertain its integrity after each sterilization.