1 ASL Toscana Centro, PO Santa Maria Nuova, Florence, Italy - pvv@unife.it.
2 Department of Anesthesia, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy.
3 Unit of Anesthesia, Polyvalent Intensive Care and Transplantation, Department of Organ Failure and Transplantation, S. Orsola-Malpighi Hospital, Bologna, Italy.
4 Unit of Anesthesia and Intensive Care, Policlinico Vittorio Emanuele, Catania, Italy.