1. Department of Anaesthesiology and Intensive Care Medicine; University Hospital of Cologne; Kerpener Str. 62 50937 Cologne Germany
2. Department of Anaesthesiology, Intensive Care Medicine, Emergency Medicine, Pain Medicine; Düren Hospital; Roonstr. 30 52351 Düren Germany
3. Faculty of Medicine; University of Latvia; Raina Blvd. 19 LV 1586 Riga Latvia
4. Department of Radiology; Düren Hospital; Roonstr. 30 52351 Düren Germany
5. Department of Anaesthesiology; HELIOS University Hospital Wuppertal; University of Witten/Herdecke; Heusnerstr. 40 42283 Wuppertal Germany