Basic Study on Transurethral Electrosurgical Vaporization of the Prostate

Summary

To clarify the best conditions for the most effective prostate vaporization, the electrode pressure on the tissue surface, the depths of the vaporization cavity and the desiccated layer of tissue, the formation of bubbles, the electrical voltage, and the resistance of the tissue were examined employing different types of electrodes.

When vaporizing a plate of porcine muscle on a balance, three different operators each manipulated grooved roller electrodes. The mean pressures applied by the operators were 20, 24, and 26 g, respectively. When the electrode pressure was changed from 10 to 40 g, the depth of the vaporization cavity increased.

A 200 W current yields a deeper desiccated layer than a 250 W or 300 W current given the same pressure.

The voltage value may also affect vaporization characteristics. Electrical resistance seemed to be determined by the resistance of the tissue before vaporization, but during vaporization the electrical resistance differed according to the electrode, and was also influenced by the contact area between the electrode and the tissue.

In an ideal electrosurgical generator, the output power increases above the setting power when the electrode is initially brought into contact with tissue, and returns to the preset level when the resistance increases at the start of vaporization.