Evaluation Background: Active Laparoscopic Electrode Shielding Systems

Here's background for our Evaluation of an active laparoscopic electrode shielding system, outlining the key considerations for making wise purchasing decisions. Learn how the technology is used, which specs are important, and what factors we test for.

Active laparoscopic electrode shielding systems conduct potentially dangerous leakage current away from the patient in the event of insulation failure or capacitive coupling. These systems consist of a small (cell-phone-size) hardware component that plugs into an electrosurgical unit (ESU) and is used in conjunction with proprietary laparoscopic instruments in procedures involving laparoscopic monopolar electrosurgery.

Monopolar electrosurgery involves the generation of a circuit through a patient's body. When a surgeon activates an ESU, it generates a high-frequency current. This current enters a patient at the point of application of an active electrode at the operative site, passes through the patient, then leaves the patient and returns to the generator via an electrode with a much larger surface area, called the return electrode.

The patient's tissues act as a resistive element in this circuit and, as a result, are heated by the current. When the current is forced through a small cross-section of tissue at the site of the active electrode application, the heat generated effectively either vaporizes or coagulates tissue, depending on the selected waveform. This heating effect is limited to the tissue immediately around the active electrode, because the current rapidly disperses via the return electrode, where it leaves the body, without significantly heating the tissues in contact with the return electrode.

Electrosurgery is used in both open and laparoscopic surgical procedures. Laparoscopic surgery introduces a different, potentially fatal set of risks to patients, caused by high-frequency leakage current. 1These risks result from the use of a monopolar electrode with a long (generally 35 to 45 cm 13.8 to 17.8 in), insulated shaft that accesses the surgical site via a cannula. There are a couple of scenarios in which high-frequency leakage current can injure a patient during monopolar electrosurgery:

1. Electrode shaft insulation failure outside of the cannula. Stray electrical leakage current passes from the active electrode shaft (e.g., through a crack in the insulation) into nontarget tissue, resulting in a lesion that might lie outside the surgeon's field of view via the endoscope. Literature indicates that one in five reusable and one in 33 disposable monopolar laparoscopic instruments could have an...