Monitoring unit and high frequency surgery system having such a monitoring unit

A monitoring unit configured to monitor a patient during an operation of a high-frequency surgery device, wherein the high-frequency surgery device is configured to separate and/or coagulate biological tissue by means of high-frequency electrical energy, the monitoring unit comprising:

• measuring electrodes, separate from and not a part of the high frequency surgery device, adapted to be disposed in a periphery of the patient;
• and
• an evaluation and control unit configured to impress a predetermined measuring alternating voltage or a predetermined measuring alternating current on the measuring electrodes, and to monitor an impedance decreasing between the measuring electrodes, to monitor (a) a time curve of the impedance, (b) a temporal change thereof or (c) both the time curve of the impedance and the temporal change thereof and wherein;
• (1) the evaluation and control unit is further configured to generate a warning signal if a relative change in impedance in the time curve of the impedance undercuts or exceeds a predetermined first limit value and/or the impedance undercuts a predetermined second limit value;
• (2) the measuring electrodes are disposed on several components in the periphery of the patient, such that the evaluation and control unit is configured to determine a spatial impedance distribution in the periphery of the patient;
• and
• (3) the monitoring unit further has a display and wherein the evaluation and control unit is configured to display the warning signal in the form of a spatial position and location of a place in the periphery of the patient at which the first limit value is exceeded or undercut and/or the second limit value is undercut on the display.