1. Department of Anesthesia and Intensive Care, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy
2. Department of Health Science, University of Florence , Florence, Italy,
3. Department of Anesthesiology, Center of Anesthesiology and Intensive Care Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
4. Cambridge University Hospitals, Trauma and Critical Care Unit, Cambridge, UK, Masimo International, Irvine, California