Affiliation: | 1. Department of Anaesthesiology, University Hospital Düsseldorf, Heinrich Heine Universit?t Düsseldorf, Germany;2. St. Elisabeth Hospital, Mayen, Germany;3. Institute of Medical Statistics, Informatics and Epidemiology, University of Cologne, Cologne, Germany;4. Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Brussels, Vrije Universiteit Brussel, Belgium |