From the Guidelines
Capacitive coupling causes thermal injury when electrical current from an active electrode transfers to nearby conductive materials through an insulating barrier, creating an unintended electrical circuit that generates heat. This occurs during electrosurgery when the active electrode's insulation is intact but in close proximity to metal instruments or tissue. The electrical energy creates a capacitor effect, allowing alternating current to flow through the insulation and into adjacent conductive materials. When this energy discharges into tissue, it produces concentrated heat that can cause burns at sites distant from the surgical field. These injuries often occur at points where tissue contacts other metal objects like retractors, creating a path to ground. The risk increases with higher voltage settings, prolonged activation of the electrosurgical unit, and when instruments are positioned parallel to each other. To prevent such injuries, surgeons should avoid parallel placement of instruments, use lower power settings when possible, and ensure proper insulation of all instruments in the surgical field, as supported by the principles outlined in 1 and 1.
Some key points to consider:
- The severity of electric injuries can vary widely, from an unpleasant tingling sensation caused by low-intensity current to thermal burns, cardiopulmonary arrest, and death, as noted in 1.
- Thermal burns may result from burning clothing that is in contact with the skin or from electric current traversing a portion of the body, as explained in 1.
- Cardiopulmonary arrest is the primary cause of immediate death from electrocution, highlighting the importance of prompt and proper treatment, as discussed in 1 and 1.
In terms of the options provided:
- A. Electric current transfer to organ touched by the metal torcher: This option is closest to describing the mechanism by which capacitive coupling can cause thermal injury, as it involves the transfer of electrical current to tissues or organs, potentially through a metal object.
- B. Sandwiching: This option does not directly relate to the mechanism of capacitive coupling causing thermal injury.
- C. Wrong energy: This option is vague and does not accurately describe the cause of thermal injury due to capacitive coupling.
- D. Failure of insulation: While failure of insulation can contribute to electrical injuries, it is not the specific mechanism by which capacitive coupling causes thermal injury, as capacitive coupling can occur even when the insulation is intact but in close proximity to conductive materials.
From the Research
Capacitive Coupling and Thermal Injury
- Capacitive coupling can cause thermal injury by releasing stray currents into neighboring non-targeted tissues, leading to electrothermal injuries 2.
- The tissue damage associated with an electric injury, including those caused by capacitive coupling, occurs when electric energy is converted to thermal energy or heat 3.
- Capacitive coupling can lead to electrical skin burn injury during laparoscopic surgery, even with intact insulation, if an open circuit is formed 4.
Mechanisms of Injury
- Direct contact, electric arc, insulation failure, direct or capacitive coupling are mechanisms of burn injuries during laparoscopy, including those caused by capacitive coupling 5.
- Capacitive coupling around active electrodes may cause serious burns and tissue damage to patients undergoing laparoscopic procedures 6.
Prevention of Injury
- Appropriate measures are available for minimizing capacitive coupling, including thorough staff training, regular safety inspections, and strict procedure performance 2.
- A coordinated team effort between perioperative nurses and surgeons can prevent life-threatening complications from laparoscopic electrosurgical procedures, including those caused by capacitive coupling 6.
- Careful manipulation must be taken to avoid creating an open circuit to prevent capacitive coupling related to electrical skin burn when using electrocautery 4.