1. Department of Anaesthesia and Critical Care; University Hospital of Würzburg; Würzburg Germany
2. Department of Cardioanaesthesia; University Hospital of Ulm; Ulm Germany
3. Department of Mathematics; University of Würzburg; Würzburg Germany
4. Department of Anaesthesia and Critical Care; Ortenau Klinikum Lahr-Ettenheim; Lahr Germany
5. Department of Neurosurgery; University Hospital of Würzburg; Würzburg Germany
6. Department of Anaesthesia and Critical Care; Mathias-Spital-Rheine; Rheine Germany