1. Department of Anesthesiology, Heidelberg University Hospital, 69120 Heidelberg, Germany
2. Department of Anesthesiology and Intensive Care Medicine, University Hospital Essen, University Duisburg-Essen, 45147 Essen, Germany
3. Clinic for Anesthesiology, Intensive Care, Emergency Medicine I and Pain Therapy, Westpfalz Hospital, 67661 Kaiserslautern, Germany