1. Department of Health Sciences, Section of Anesthesia, Intensive Care and Pain Medicine, University of Florence, Florence, Italy
2. Department of Anesthesia and Intensive Care, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy
3. Division of Pulmonary Critical Care & Sleep, Department of Medicine, Brown University, Providence, RI, USA
4. Department of Neurosciences, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy