1. Fraunhofer Institute for High Frequency Physics and Radar Techniques, 53343 Wachtberg, Germany
2. Philips Chair of Medical Information Technology, RWTH Aachen University, 52074, Germany
3. Institute for Integrated Systems, Ruhr-University Bochum, 44801, Germany
4. Department of Anaesthesiology, University Hospital RWTH Aachen, 52074, Germany