1. HELIOS Klinikum Krefeld; Department of Anaesthesiology, Intensive Care Medicine, and Pain Therapy; Lutherplatz 40 Krefeld Germany 47805
2. Witten/Herdecke University; IFOM - The Institute for Research in Operative Medicine, Faculty of Health, Department of Medicine; Ostmerheimer Str. 200 Cologne Germany 51109
3. University of Cologne; Institute of Medical Statistics, Informatics and Epidemiology; Kerpener Str. 62 Cologne NRW Germany 50937
4. Marien-Hospital Erftstadt; Department of Anaesthesiology and Intensive Care; Münchweg 3 Erftstadt Germany
5. Operatives Zentrum Medicenter; Abteilung für Chirurgie; Arnoldsweiler Str. 23 Dueren Germany 52351
6. Jagiellonian University, Medical College; Department of Interdisciplinary Intensive Care; Krakow Poland