Unipolar electrosurgery in operative laparoscopy. Capacitance as a potential source of injury

Abstract

Objective: To determine whether capacitive "stray" currents that can be generated during unipolar laparoscopic electrosurgery are likely to cause unintentional organ injury.

Study design: In a controlled laboratory setting, the passage of capacitive current across the insulated portion of unipolar, 5-mm laparoscopic instruments was assessed for its ability to cause damage to biologic tissues.

Results: Modulated (coagulating) current output at power settings as low as 20-25 W led to apparent passage of current across the insulated portion of some laparoscopic instruments with thin insulation. This was accompanied by thermal damage to biologic tissues and instrument insulation.

Conclusion: Our findings can explain unintentional injury during unipolar electrosurgery. The risk of such injury can be reduced by surgeon awareness, low generator output power and use of instruments with ample insulation. Thin insulation is more likely to be encountered with disposable than with multiuse instruments.