• Thomas N Robinson, Kelli S Barnes, Henry R Govekar, Greg V Stiegmann, Christina L Dunn, and Francis T McGreevy.
• Department of Surgery, University of Colorado School of Medicine, Aurora, CO, USA. thomas.robinson@ucdenver.edu
• Ann. Surg.. 2012 Aug 1;256(2):213-8.

Objectives(1) To determine if antenna coupling occurs in common operating room scenarios. (2) To define modifiable clinical variables that reduce the magnitude of antenna coupling.BackgroundMechanisms of electrosurgical burns where monitoring devices contact the surgical patient are unclear. Antenna coupling occurs when the "bovie" active electrode (electrically active transmitting antenna) emits energy, which is captured by a nonelectrically active wire (electrically inactive receiving antenna) in close proximity without direct contact.MethodsMonopolar radiofrequency energy was delivered to a laparoscopic instrument (electrically active transmitting antenna), whereas other nonelectrically active wires (electrically inactive receiving antenna) including electrocardiogram (EKG) lead, nonactive "bovie" pencil, and nerve electrode monitor were placed in proximity. Temperature changes of tissue placed adjacent to the electrically inactive receiving antennae were measured.ResultsNonelectrically active wires (receiving antenna) increase tissue temperature when lying parallel to the active electrode cord: EKG pad 2.4°C ± 1.2°C (P = 0.002), "bovie" pencil tip 90°C ± 9°C (P < 0.001), and nerve electrode monitor 106°C ± 12°C (P < 0.001). Factors that reduced the heat generated by antenna coupling included the following: increasing angulation between transmitting and receiving antennae (parallel = 90°C ± 9°C; 45° angle = 53°C ± 10°C; perpendicular = 35°C ± 11°C; P < .001), increasing separation distance between parallel transmitting and receiving antenna (<1 cm = 90°C ± 9°C; 15 cm = 44°C ± 18°C; 30 cm = 39°C ± 2°C; P < .001); and decreasing generator power setting (15 W = 59°C ± 11°C; 30 W = 90°C ± 9°C; 45 W = 98°C ± 8°C; P < .001).ConclusionsAntenna coupling occurs in common operating room scenarios. Simple, practical measures by the surgeon, such as orienting the receiving antenna at a greater angle and with greater separation to the active electrode cord, or lowering the generator power setting reduce antenna coupling.

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