1. Institute of Anaesthesiology, University Hospital Zurich, University of Zurich , Zurich , Switzerland
2. Institute of Physiology, University of Zurich , Zurich , Switzerland
3. Department of Surgery, Rush University Medical Centre , Chicago, Illinois , USA
4. Department of Surgery, Cantonal Hospital Winterthur , Winterthur , Switzerland
5. Departments of Epidemiology and Biostatistics, Epidemiology, Biostatistics and Prevention Institute, University of Zurich , Zurich , Switzerland
6. Department of Surgery, Triemli Hospital Zurich , Zurich , Switzerland
7. Institute of Anaesthesiology, Cantonal Hospital Winterthur , Winterthur , Switzerland
8. Department for Anaesthesiology, Intensive, Rescue and Pain Medicine, Cantonal Hospital St Gallen , St Gallen , Switzerland