Department of Surgical, Oncological and Oral Science (Di.Chir.On.S.), University of Palermo, Department of Anaesthesia, Intensive Care and Emergency, Policlinico Paolo Giaccone, Italy. Dipartimento di Anestesia, Rianimazione ed Emergenza-Urgenza, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy; Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy. Electronic address: giacomo.grasselli@unimi.it. Department of Cardiovascular Medicine, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milan, Italy. Department of Anesthesia and Critical Care, Azienda-Ospedaliero Universitaria S. Luigi Gonzaga, Orbassano, Italy; Dipartimento di Oncologia, Università degli Studi di Torino, Turin, Italy. ASST Grande Ospedale Metropolitano Niguarda, Anestesia e Rianimazione 1, Milan, Italy. Department of Health Science, University of Florence, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy; Department of Anesthesia and Critical Care, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy. Department of Morphology, Surgery and Experimental Medicine, Azienda Ospedaliera-Universitaria Arcispedale Sant'Anna, University of Ferrara, Ferrara, Italy. Department of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy; Department of Emergency and Intensive Care, San Gerardo Hospital, Monza, Italy. Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy. Dipartimento di Anestesia, Rianimazione ed Emergenza-Urgenza, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy. Department of Cardiovascular Medicine, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milan, Italy; Department of Anesthesia and Critical Care, Azienda-Ospedaliero Universitaria S. Luigi Gonzaga, Orbassano, Italy.