CQM - The unknown risk in electrosurgery

Abstract

The principle of a CQM system in electrosurgical units (ESU) is shown and various such systems are discussed. Theoretical calculations of the current distribution inside the patient's skin showed the influence of the size and shape of a neutral electrode (NE). Measurements of the temperature increase under a NE on a suitable test device showed the relation between the change of the CQM impedance for a detached NE, the skin properties, and the temperature increase with a reduced contact area of the NE. It could be shown that CQM systems that activate an alarm simply when the CQM impedance exceeds a fixed upper limit are not safe in all circumstances. Systems taking into account the skin properties of the patient by measuring an initial CQM impedance and reacting to a relative impedance increase proved to be safe under all tested circumstances.