1. Department of Anaesthesiology and Intensive Care Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50937 Köln, Germany
2. Department of Cardiothoracic Surgery and Intensive Care Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50937 Köln, Germany
3. Department of Ophthalmology, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50937 Köln, Germany