Electrosurgery is a simple surgery technique that is sometimes difficult to explain. It involves using radio frequencies to cut and coagulate a patient’s tissue during a surgery, allowing for a high level of bleeding control. It’s an integral part of OR procedures, and it’s been used successfully for nearly 100 years. Odds are, if you’ve had a major surgery, you’ve been treated with electrosurgery.
Electrosurgery vs. Electrocautery
Electrosurgery is often confused with electrocautery, partially because there’s some overlap in function. Electrosurgery can coagulate and cauterize tissue, and it’s frequently used for that. The difference is in how this is achieved.
Electrocautery is when a rod or other metal instrument is heated with an electrical current. That heated metal, like the cautering irons of old, is then applied to the target area to seal tissue and staunch bleeding. This is its only purpose.
Electrosurgical units (ESUs) function by energizing an active electrode with a high-frequency electrical charge. That charge (which doesn’t heat the electrode) is then applied to the tissue of the patient, where the frequency of the charge heats the tissue, causing either coagulation or fulguration via desiccation (depending on how steadily the current is applied).
In other words, in electrocautery, it is the object that heats the tissue, while electrosurgical equipment uses radiofrequency ablation, and it’s the electrical current that does the heating, not the metal instrument.
Circuits
While original designs were connected to ground, modern ESUs use a safer, ground-insulated design, where a circuit is created between the ESU and the patient. In a monopolar design, this involves the generator to create the current, the active electrode to provide the cutting and coagulation on the patient, the patient’s body, and then the return electrode (or “dispersive electrode”) that completes the circuit. Bipolar designs use to active electrodes, and the current only passes through the tissue that passes between the two (often, these are forcep or clamp designs).
On major concern is the current density at the site of the return electrode which, if too high, can cause burns. There are several new developments designed to assist in avoiding this risk, among them Return Electrode Contact Quality Monitor (RECQM) generators, and reusable return electrodes.
Cutting vs. Coagulation
There are two primary settings on an ESU. The first is a “pure cut” setting, and the other is a coagulation setting, or “coag.”
Pure Cut
Cutting is done using continuous current. It’s a high current, low voltage waveform that produces a very high temperature, and cells are blown apart via explosive dehydration. The thermal damage profile (i.e. the collateral damage on either side of the incision) of the pure cut mode is very narrow, but there is no hemostasis on this setting, meaning that bleeding is not controlled.
Coag
On this setting, energy is pulsed, with an active current only 6% of the time. This interrupted delivery of current is high voltage with a low current, resulting in lower temperatures than the pure cut setting. The resulting effect is that cells clump together, forming eschar and coagulum, and preventing bleeding. This does, however, result in a wider thermal damage profile.
Blends
Typically, neither the pure cut setting nor the coag setting are used in the OR. Instead, there are three standard “blends,” where the two are combined to pulse at a certain rate and frequency. This provides the benefits of coagulation during incisions, though at the cost of slightly wider thermal damage profile than pure cut.
If you are expecting a surgery, and the surgeon’s plan to use electrosurgery, know that you are in good hands. Modern electrosurgery equipment is very safe, and medical professionals are very familiar with its use. Recovering from electrosurgery is no different than from scalpel incisions. Following doctor’s orders and plenty of rest goes a long way.
Stephen Dangerfield
Latest posts by Stephen Dangerfield (see all)
- Electrosurgery: What It Is and How It Works – August 2, 2017
