1. Institute of Anaesthesiology, University Hospital Zurich, 8091 Zurich, Switzerland
2. Departments of Epidemiology and Biostatistics, Epidemiology, Biostatistics and Prevention Institute, University of Zurich, 8001 Zurich, Switzerland
3. Institute of Anaesthesiology and Intensive Care Medicine, Clinic Hirslanden Zurich, 8032 Zurich, Switzerland
4. Department of Anaesthesiology, Intensive Care, Emergency, and Pain Medicine, University Hospital Wuerzburg, University of Wuerzburg, 97080 Wuerzburg, Germany
5. Department of Anaesthesiology, Intensive Care Medicine, and Pain Therapy, University Hospital Frankfurt, Goethe University Frankfurt, 60323 Frankfurt, Germany
6. Department of Anaesthesiology, Intensive Care Medicine, and Pain Therapy, Hospital Clinic of Barcelona, University of Barcelona, 08036 Barcelona, Spain