1 Department of Anesthesia and Intensive Care, AOU Policlinico Vittorio Emanuele, Catania, Italy. Electronic address: filipposanfi@yahoo.it.
2 Intensive Care Unit, Nepean Hospital, Sydney, Australia.
3 Department of Anesthesia and Intensive Care, AOU Policlinico Vittorio Emanuele, Catania, Italy.
4 Unit of Intensive Care Medicine, Department of Emergency and Urgency-Medicine, Surgery and Neurosciences, University Hospital of Siena, Siena, Italy.