From the Guidelines
Capacitive coupling causes thermal injury by transferring electrical energy through insulation, leading to unintended tissue heating, and the most likely cause of this is electric current transfer to an organ touched by a metal object, such as a trocar, which acts as a conductor. This occurs when an electrical current from an active electrode creates an electrical field that induces current in nearby conductive materials, even without direct contact 1, 2. During surgical procedures using electrosurgical devices, capacitive coupling can develop when the active electrode's insulation creates a capacitor effect, allowing energy to transfer to adjacent tissues or instruments. This transferred energy generates heat in unintended areas, potentially causing burns to tissues outside the surgical field. The risk increases with higher voltage settings, damaged insulation, long thin electrodes, and when metal trocars or instruments are positioned close to the active electrode without proper grounding.
Some key points to consider in preventing such injuries include:
- Using lower voltage settings when possible
- Inspecting instrument insulation regularly
- Avoiding metal-to-metal contact between the active electrode and other instruments
- Ensuring proper grounding of all equipment
- Being aware of the potential for capacitive coupling and taking steps to minimize its occurrence
It's also important to note that the severity of thermal injury depends on the amount of energy transferred, the tissue's resistance, and exposure duration. Therefore, prompt recognition and treatment of thermal injuries are crucial in minimizing their impact on patient outcomes. The most recent guidelines, such as those from 2025, emphasize the importance of evidence-based management of heat-related illnesses, including heat stroke, which can be a consequence of severe thermal injury 3.
From the Research
Capacitive Coupling and Thermal Injury
- Capacitive coupling can cause thermal injury due to the transfer of electrical energy to the body, resulting in burns [(4, 5, 6)].
- This can occur even with intact instrument insulation, and the risk is increased when an open circuit is formed 6.
- The electrical energy can cause damage to tissues, leading to thermal burns, and the extent of the injury can be severe [(4, 7, 6)].
Mechanism of Injury
- Capacitive coupling can release stray currents into neighboring non-targeted tissues, causing indirect electrosurgical damage 5.
- The electrical response can be greater when there is increased contact with the tissue, and the risk of injury is higher with certain types of instruments and procedures [(5, 6)].
Prevention and Management
- Measures to minimize capacitive coupling include thorough staff training, regular safety inspections, and strict procedure performance 5.
- The use of shielded instruments with active electrode monitoring (AEM) can help prevent electrosurgical injuries 4.
- In the event of a thermal burn injury, priorities for emergency resuscitation include stabilization of airway and breathing, intravenous fluid administration, pain control, and local wound care 8.