1. Intensive Care Unit, Hospital General Universitario Gregorio Marañón, 28007 Madrid, Spain
2. Intensive Care Unit, Medicine Department, University of Cádiz, University Hospital of Jerez, INIBiCA, 11407 Jerez, Spain
3. Intensive Care Unit, Hospital Universitari Vall d’Hebron, 08035 Barcelona, Spain
4. Intensive Care Department URV/IISPV/CIBERES, Hospital Universitari Joan XXIII, 43005 Tarragona, Spain
5. Intensive Care Department, Hospital Universitario de Cruces, 48903 Barakaldo, Spain
6. Department of Intensive Care Medicine and Intensive Care Unit, Hospital Ramón y Cajal, 28034 Madrid, Spain
7. Intensive Care Service, Hospital Universitario Marqués de Valdecilla, 39008 Santander, Spain
8. Intensive Care Service, Hospital Universitario Dr. Peset. Fundacion Micellium, C/La Armada Española, L’eliana, 46017 Valencia, Spain