What equipment is used in electrosurgery?

Electrosurgical instruments are high-frequency current surgical systems used in operating rooms, encompassing various surgical devices such as high-frequency electrosurgical units, large vessel sealing systems, ultrasonic scalpels, argon plasma coagulators, endoscopic electrosurgical units, and laser scalpels. These instruments enable surgeons or computer systems to control cutting depth and coagulation speed during procedures, achieving hemostasis and tissue sealing.

Here are several electrical terms to introduce:

Electric Current: The flow of electrons per unit time; unit: Ampere (A).

Electric Circuit: A closed path for the flow of electrons.

Resistance: The opposition to the flow of electric current; unit: ohm.

Voltage: The pressure forcing current through resistance; unit: volt.

Physical characteristic of electric current: It always flows toward the earth, toward the path of least impedance.

Understanding the above fundamental electrical concepts will further aid our explanation of electrically powered surgical instruments. Below, we will introduce various electrosurgical instruments one by one:

(一) Monopolar Electrosurgical Unit

A monopolar electrosurgical unit is an electrosurgical device that utilizes high-frequency current exceeding 200 kHz within a single circuit to generate thermal energy and electrical discharge for tissue cutting and hemostasis. The active electrode is positioned at the device's tip, while the return electrode is located elsewhere. Current flows through the human tissue between these two electrodes.

The typical operating voltage for a monopolar electrosurgical knife: Coagulation: 3000–9000 V; Cutting: 1350–4000 V.

（二) Bipolar Electrosurgical Unit

A bipolar electrotome is a high-frequency current generator. When the bipolar electrocoagulation instrument makes good contact with tissue, the thermal energy generated between the two electrodes of the bipolar forceps is used to electrocoagulate and stop bleeding in human tissue.

The active electrode and loop electrode are integrated into the same instrument, confining the current exclusively to the target tissue between the electrodes. Working voltage for bipolar electrosurgical instruments: 500–1200 V.

（三）Argon Plasma Coagulator (APC)

The argon plasma coagulator (APC) is a type of high-frequency electrosurgical unit that ionizes argon gas to generate argon plasma, which conducts high-frequency electric current. This process produces a thermal effect on the target tissue, achieving hemostasis (stopping bleeding) and tissue inactivation. The argon plasma coagulator is also known as argon plasma coagulation.

（四）Ultrasonic Scalpel

The ultrasonic scalpel is a generator capable of producing ultrasonic energy and mechanical vibrations. It acts on a metal probe (scalpel head) via an ultrasonic frequency generator, causing the scalpel head to undergo mechanical oscillation (with an amplitude of 50-100 μm) at a frequency of 55.5 kHz. This process converts electrical energy into mechanical energy, which in turn leads to vaporization of fluids in tissues, breakage of protein hydrogen bonds, cell disintegration, protein coagulation, and blood vessel closure—ultimately achieving the effects of tissue incision and hemostasis.