1 Department of Cardiovascular, Respiratory, Nephrological, Anesthesiological and Geriatric Sciences, University of Rome, "La Sapienza," Policlinico Umberto Primo, Rome, Italy Department of Anesthesia and Intensive Care, AUO Policlinico Vitorrio Emanuele, Catania, Italy Department of Anesthesiology, Intensive Care, Emergency Medicine, Transfusion Medicine and Pain Therapy, Protestant Hospital of the Bethel Foundation, Bielefeld, Germany Department of Anesthesiology, Intensive Care and Pain Medicine, University Hospital of Muenster, Albert-Schweitzer-Campus 1, Muenster, Germany.