Abstract: A method and a measurement apparatus are provided for determining the transition impedance between two electrode parts of a subdivided neutral electrode used in high-frequency surgery. These makes it possible for the purely capacitive component of the transition impedance to be measured. For this purpose a resonant-frequency shift is measured, which occurs when a basic resonant circuit is expanded to an expanded resonant circuit by incorporating the two electrode parts into it in parallel. In particular, in order to determine the basic resonant frequency of the basic resonant circuit and/or the sample resonant frequency of the expanded resonant circuit, the phase shift between current and voltage is measured and the frequency is adjusted until current and voltage are in phase.

Abstract: The invention relates to a neutral electrode for HF surgery and to an electrically conductive gel. The neutral electrode comprises at least one electrically conductive section that can be brought into contact with a section of a patient's body. In order to enable the contact resistance to be reduced in a simple and economical manner, in particular in cases of problematic skin and/or tissue conditions, the neutral electrode comprises circulation-promoting means that enhance blood flow through the section of the body that is in contact with this electrode section. The invention also relates to a conductive gel for application of a neutral electrode to a section of a patient's body that contains capsaicin or similar means for promoting circulation.

Abstract: An apparatus for the interstitial coagulation of tissues includes at least one electrode by way of which an HF coagulation current can be conducted into the tissue of a patient. The electrode is constructed as a three-dimensional body that can be expanded to various states of expansion, or is attached to such a body, so that by continuous or stepwise expansion of the body the electrode can be kept in constant electrical contact with the tissue during coagulation. In this way the apparatus enables the tissue treatment to be more uniformly distributed.

Abstract: The invention relates to a method for operating an instrument (30) for use in high-frequency surgery that is connected to at least one device (10) for performing high-frequency surgery. According to the method, operational data of the device (10) is recorded at least during the first use of the instrument (30) that is connected to the device. The operational data is sent to a storage device (33), which is connected to the instrument (30) and in which the operational data is stored. The operational data is sent to a data acquisition device during a resumed or additional use and/or when testing the instrument. The device (10) is set, according to the operational data, during the first use such that the instruments (3) can be operated in the same manner as during the first use and/or the operational data can be evaluated in order to test the instrument (30).