1. Department of Anaesthesiology, Johannes-Gutenberg Universität Mainz, Mainz, Rhineland-Palatinate, Germany
2. Department of Anaesthesiology and Critical Care Medicine, Central hospital of the German armed forces, Koblenz, Rhineland-Palatinate, Germany
3. Institute of Medical Biostatistics, Epidemiology and Informatics, University Medical Centre of the Johannes Gutenberg-University Mainz, Mainz, Rhineland-Palatinate, Germany