How does capacitive coupling cause thermal injury due to electric current transfer to an organ touched by a metal object, such as a (Laparoscopic Linear Cutter, LL)?

From the Guidelines

Capacitive coupling causes thermal injury through electric current transfer to organs touched by the metal trocar (option A). This occurs when electrical energy from an active electrode creates an electrical field that induces current in nearby conductive objects without direct contact 1. During procedures, the insulation on instruments creates a capacitor-like effect where energy can transfer to metal trocars or instruments. If these metal objects contact patient tissue, the transferred energy can cause unintended burns at sites distant from the surgical field. This happens because the electrical circuit completes through the patient's tissue, with the current seeking the path of least resistance to the return electrode. The risk increases with higher voltage settings, prolonged activation times, and when instruments are placed close to metal trocars. Unlike insulation failure which involves direct leakage through damaged insulation, capacitive coupling can occur even with intact insulation, making it particularly dangerous as these injuries may occur outside the surgeon's field of view.

Key points to consider:

• Electric current can cause thermal burns, cardiopulmonary arrest, and death 1
• The severity of electric injuries can vary widely, from an unpleasant tingling sensation to thermal burns and death 1
• It is essential to turn off the power at its source before assessing the victim of an electric shock 1
• All victims of electric shock require medical assessment because the extent of injury may not be apparent 1
• The use of electrocautery is a risk factor for postpolypectomy bleeding and mural injury 1
• The choice of electrocautery settings relies on the endoscopist’s preference and experience, and insufficient data exist to make a specific recommendation for electrocautery settings 1

From the Research

Capacitive Coupling and Thermal Injury

• Capacitive coupling can cause thermal injury due to the transfer of electrical energy to non-targeted tissues 2
• This can occur even with intact instrument insulation, and is a rarely mentioned electrosurgical complication in monopolar laparoscopy 2
• The risk of capacitive coupling can be increased by factors such as increased contact with the cystic wall, particularly with cysts less than 3 cm in diameter 2

Causes of Thermal Injury

• Electric current transfer to organs touched by the metal torcher (A) is a possible cause of thermal injury, but is not directly related to capacitive coupling
• Failure of insulation (D) is a known cause of thermal injury, and can be detected through routine testing of electrosurgical instruments 3
• Wrong energy (C) and sandwiching (B) are not directly related to capacitive coupling or thermal injury

Prevention of Thermal Injury

• Thorough staff training, regular safety inspections, and strict procedure performance can help minimize the risks of capacitive coupling and thermal injury 2
• Standardizing processes, preoperatively assessing the risks for electrosurgical injuries, and participating in education activities on electrosurgical safety can also help prevent injuries from occurring 4