Table of Contents
- Procedure Summary
- Authors
- Youtube Video
- What is Electrosurgery?
- What are the Risks of Electrosurgery?
- Video Transcript
Video Description
A foundational review of monopolar electrosurgery, covering key principles, safe usage, waveform types, and clinical applications for gynecologic procedures.
Presented By
Affiliations
University of Manitoba, Rady Faculty of Health Sciences
Watch on YouTube
Click here to watch this video on YouTube.What is Electrosurgery?
Demystifying electrosurgery focuses on understanding the principles and safe application of monopolar energy in surgical procedures. Key points include:
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Core Principle: Monopolar electrosurgery relies on an electrical circuit where alternating current passes from an electrosurgical unit (ESU) through the surgical instrument, across tissue, and back to a dispersive electrode on the patient. Tissue resistance converts electrical energy into heat, allowing for cutting or coagulation.
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Current Types: Cutting current delivers continuous high-frequency energy with low voltage for precise tissue division and minimal thermal spread. Coagulation current alternates between peaks and pauses, creating high voltage and low current for tissue heating and haemostasis. Blended settings combine both for simultaneous cutting and coagulation.
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Tissue Effects: Different applications include vaporisation (cutting current, no tissue contact, creating a scalpel-like effect), fulguration (coagulation current without contact, causing surface charring), and desiccation (direct contact with either current, providing haemostasis).
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Clinical Relevance: Monopolar energy remains a cost-effective and versatile tool despite advances in ultrasonic and bipolar technology. Mastery of settings, technique, and instrument choice enables precise tissue handling while minimising collateral damage.
What are the Risks of Electrosurgery?
Monopolar energy carries significant risks if not applied carefully, largely due to unintended tissue heating and electrical spread. Potential complications include:
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Direct Injury: Accidental activation or excessive energy delivery can cause deep thermal burns or perforation of adjacent organs.
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Direct Coupling: Energy can transfer to nearby instruments or metal objects in contact with the active electrode, causing unintended burns.
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Insulation Failure: Breaks in the instrument’s insulation allow current to escape and damage surrounding tissue without visible contact.
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Capacitive Coupling: Current can pass through intact insulation when instruments are in close proximity, particularly in laparoscopic settings, leading to hidden thermal injury.
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Delayed Complications: Thermal injuries to bowel or bladder may not be apparent intraoperatively and can present postoperatively with leaks, fistulas, or infection.
Careful power selection, instrument inspection, and strict adherence to electrosurgical safety principles are essential to reduce these risks and ensure effective, precise outcomes.
Video Transcript:
Demystifying electrosurgery, reviewing the basics of monopolar energy. The authors have no relevant disclosures. Our objectives are to review the principles of electrosurgery relevant to monopolar energy, outline the different characteristics for cutting, coagulation, and blended settings, and demonstrate the clinical applications of monopolar energy through vaporisation, fulguration, and desiccation.
Although there have been many advances in ultrasonic and bipolar disposable technology, monopolar energy offers a unique, complementary, and cost-effective option for surgeons. The application of monopolar energy can be modified based on different settings and techniques, but there is a high potential for complications through unintended tissue damage from direct injury, direct coupling, insulation failure, or capacitive coupling. An understanding of the principles behind monopolar energy can facilitate safe and effective surgery.
One of the fundamental principles of electricity is that it requires a complete circuit. In monopolar circuits, an alternating current flows between an electrosurgical unit, or ESU, instrument, and tissue. The alternating current often follows a path of least resistance, with a dispersive electrode typically attached to the skin surface over the proximal thigh.
Now, we can zoom in and consider what is happening at the interface between a surgical instrument and the patient’s tissue. When voltage is applied to tissue, a circuit is created between the voltage source and the tissue. Within this circuit, voltage is dependent on the flow of electrons, or current, and the resistance of the circuit, the tissue. This is known as Ohm’s Law. The resistance of tissue causes the electrical energy to be converted into thermal energy, heating the surrounding tissue. As the tissue is heated, the tissue is damaged or destroyed.
The electrical energy delivered at any point in the circuit per unit of time is known as power, measured in joules per second or watts. Power is proportional to the current and voltage of a circuit, and is dependent upon the settings of the ESU. So, for the same power settings, we can produce high current, low voltage circuits, or low current, high voltage circuits.
It is important to distinguish between the different types of currents that can be used in monopolar energy. A cutting current produces a continuous high-frequency flow of electrons without pausing in zero polarity. In simplified terms, the current is on 100% of the time. A coagulation current is characterised by an alternation between peak polarity and zero polarity. One can think of the current only being on 6% of the time, and off the remaining 94%.
So, for the same power settings, commonly 30 W and 30 W, a cutting current is characterised by high current and low voltage, whereas a coagulation current is characterised by low current and high voltage. Due to these characteristics, cutting current can achieve precise cutting without significant dispersion, while coagulation current achieves exaggerated tissue heating and thermal spread. A blended current has a blended waveform where it is interrupted at different intervals, supplying a current that exhibits both cutting and coagulation properties.
Many laparoscopic instruments can be used to employ monopolar energy, including a monopolar hook, spatula, and Metzenbaum scissors. The desired clinical effects of monopolar energy are primarily dependent on the circuit activated, cutting, or coagulation, and level of contact with tissue. However, other factors, such as the power generated by the ESU, the surface area of the instrument used, tissue tension, and the duration of circuit activation all can be varied as needed.
Here we are going to focus on the dynamic interplay between the current applied and level of contact with tissue in the application of monopolar energy. Vaporisation is achieved with a cutting current and no tissue contact. An instrument hovers over tissue, and when activated, the electrical discharge ionises the air between the electrode and tissue. With the continuous flow of current, a rapid and intense heating of cells occurs, ultimately causing intracellular water to vaporise.
This results in the rapid release of heat from tissue with a contrasting cooling effect. With this, there is limited thermal spread, allowing for precise destruction and division of tissue.
In this video, rectal sigmoid adhesions will be brought down from the bladder peritoneum to gain access to the left IP ligament and adnexa laying posteriorly. Here you can see the Metzenbaum scissors hovering just above the tissue and being activated with a cutting current. This method of vaporisation allows for a scalpel-like effect.
Vaporisation can be effectively applied in the setting of excision of endometriosis. Here we have an endometrial deposit on the right posterior sidewall. The Metzenbaum scissors are again activated just above the tissue, with minimal thermal spread. You can also note there is a small vessel bleed, where the scissors make direct contact with the tissue and are activated. This provides greater thermal spread and tissue damage known as desiccation, which we will review further soon.
Similar to vaporisation, with fulguration an instrument has no contact with tissue, however, the instrument is activated with a coagulation current, which produces intermittent sparks of energy through ionisation of the air in a high voltage circuit. This then causes a spray effect, with broad charge dispersion and superficial coagulation of tissue. Depending on tissue tension, division can also be achieved.
When bleeding is encountered during this bladder flap dissection the Metzenbaum scissors are seen hovering over the tissue and are activated with a coagulation current. If you look closely, you can see sparks as a result of the ionisation of air. This technique essentially allows for painting or charring of the bladder peritoneum and subsequent haemostasis.
In this hysterectomy video, the left lateral aspect of a colpotomy is being performed with a spatula. Coagulation current is used hovering just above the tissue. This results in a greater charge dispersion than what can be achieved with vaporisation. On tension with the colpotomy cut tissue is not only destroyed and coagulated, but also divided. At times, you can note the spatula making direct contact with the tissue desiccating without division.
Here you can see the operator flipping the spatula to have a smaller surface area. This then allows for more precision in their delivery of energy and division of tissue. Desiccation occurs when an electrode is activated while making direct contact with the tissue with either a cutting or coagulation current. This is an effective way to provide haemostasis.
In this video, the operator is about to create their bladder flap with Metzenbaum scissors following the division of the left round ligament, however, there is some bleeding from collateral branches within the broad ligament. The scissors are then placed in direct contact with the tissue and activated, providing the necessary thermal spread for haemostasis. Now, we can see vaporisation, fulguration, and desiccation applied simultaneously in the setting of bladder flap development at the time of hysterectomy.
Here we can see Metzenbaum scissors vaporising the tissue during the initial bladder flap development. Later on, bleeding is noted along the bladder peritoneum. The scissors are again seen hovering just above the tissue, but this time activated with coagulation current, essentially painting the area through fulguration. Now, here we see a larger area of bleeding along the bladder peritoneum. This time, the sisters make direct contact with the tissue, utilising a desiccative technique for haemostasis.
In summary, monopolar energy can be applied by activating different currents to achieve the desired tissue effects of vaporisation, fulguration, and desiccation. Many factors can be further modified. It is critical to be aware of the possible complications of monopolar energy, particularly when activating a coagulation current. By harnessing the complexities of monopolar energy, one will be able to provide safe and effective surgical care. Thank you for joining us and listening.
