How Frequency of Electrosurgical Current and Electrode Size Affect the Depth of Electrocoagulation

Many factors affect the depth of electrocoagulation.

To evaluate the effect of current frequency and electrode size on the depth of electrocoagulation.

In this in vitro study, 4 cylindrical electrodes (2, 2.3, 3, and 4 mm) were used to apply 3 electrosurgical currents (0.4, 1.5, and 3 MHz) to bovine liver. Each electrode was placed at different points on the surface of the liver, and energy at various levels and frequencies was delivered to the tissue. Subsequently, cross-sections of the liver were analyzed.

Coagulation started at the periphery of the electrode-tissue contact area. With higher energy levels, coagulation spreads to involve the remainder of the contact area. Neither the frequency nor the electrode size had any effect on this coagulation pattern. The frequency of the current also did not show any relation with depth of coagulation; however, there was a direct correlation between the size of the electrode and the depth of coagulation.

Larger-tip electrodes provided deeper coagulation compared with finer-tip electrodes.