1. 1Department of Anesthesiology, Intensive Care and Emergency Medicine, Pain Therapy, Bergmannstrost Hospital Halle, Halle, Germany; Medical Faculty, Martin-Luther University Halle-Wittenberg, Halle, Germany.
2. 2Clinical Trial Centre, University of Leipzig, Leipzig, Germany.
3. 3Department of Anesthesiology, University of Colorado School of Medicine, Aurora, Colorado.