Helmut Wurzer

A spark counter as a control unit of a radio frequency surgery device

A new approach in radio frequency (rf) electrosurgery, used for tissue treatment, is achieved by using a new process control method. An external control unit allows a commonly available rf-generator to automatically supply the appropriate power for differing tissue types, thus ensuring best cutting quality. The sparks, generated during the scalpel electrode interaction with the tissue, appear statistically distributed. The spark rate depends on various factors and is monotonic with the supplied electrical power. This allows it to be used as the controlled variable in the cutting process. The ac current passing through the tissue is evaluated by an external control unit using an analyzation algorithm to determine the number of sparks. The external unit is comprised of a system, which measures the spark rate, and a subsequent proportional integral (P.I.) controller. The functionality of the control method as well as the electrical circuitry is verified through cuts with different degrees of carbonization and cuts through tissue heterojunctions.

Optimization of tissue interaction in electrosurgery

The number of sparks per time window between a scalpel electrode and tissue is a measure of the electrosurgical cutting ability with a strong dependency on the electrical power dissipation. This parameter used as controlled variable in an appropriate circuit allows controlling electrosurgical treatments with best cutting quality at any kind of tissue. It is presented the effect of this control unit with regard to therapeutic aspects and smoke emission. Histological investigations of porcine muscular tissue reveal drastically reduced boiled zones and zones of oedema formation at controlled cuts in comparison to common uncontrolled treatments. A further comparison of the harmful components in the electrosurgical smoke shows the great advantage of the new system.

Process controlling of a high-frequency cauter during tissue treatment

We present the process controlling of a high-frequency surgery generator during tissue treatment. Hereby, the temporal behavior of the voltage and the current are measured and then the finger print of the generated light arc in the electrical characteristic is analyzed by the control unit. This unit forces the high-frequency generator to supply an appropriate electrical power for different kinds of tissue. The functional ability is verified by cuts with different set points of the controlled variable, therefore, different degrees of slough, and cuts through tissue heterojunctions.