1. Department of Anesthesiology and Critical Care Medicine, Patras University Hospital, 26500 Rion, Greece
2. Department of Anesthesiology, Washington University School of Medicine, Campus Box 8054, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
3. Department of Anesthesiology and Critical Care Medicine, Patras University School of Medicine, 26500 Rion, Greece
4. Department of Internal Medicine, Patras University School of Medicine, 26500 Rion, Greece