1. Department of Anaesthesia; Klinikum Bamberg; Bamberg; Germany
2. Department of Anaesthesia; Universitätsklinkum Aachen; Aachen; Germany
3. Department of Anaesthesia; Universitair Zieckenhuis Leuven; Leuven; Belgium
4. Department of Occupational, Social and Environmental Medicine; University Medical Center Göttingen; Göttingen; Germany