Thermal profiles of electrocauteries, the Nd:YAG laser, and the electromagnetic-field focusing system

Electromagnetic-field focusing (EFF) is a method of converging induced eddy current onto a pointed tip of a tuned length return circuit in the near field of a resonator, which results in the production of high temperature. Previously reported applications of this method include various devices for local hyperthermia and a precision surgical device. The latter is currently being used in human clinical trials under two investigational device exemptions from the Food and Drug Administration. In the present work, the thermal profile produced in a uniform, tissue-simulating phantom by the hand-held probe of the surgical EFF system is compared with those produced by mono- and bipolar electrocauteries and by a contact Nd:YAG laser. At the equivalent power setting and 2-cm insertion depth, the EFF probe was shown to have a tighter thermal profile than the monopolar electrocautery or the contact Nd:YAG laser. This finding is consistent with earlier histologic evidence that brain cortical tissue cut by the surgical EFF probe had minimal thermal damage in the tissue surrounding the incision.