[1] Univ Messina, Dept Biomed & Dent Sci Morphol & Funct Images BI, Pulmonol Unit, Messina, Italy
[2] Sheffield Teaching Hosp, Dept Crit Care, Sheffield, S Yorkshire, England
[3] Hosp Morales Meseguer, Dept Intens Care & Noninvas Ventilatory Unit, Intens Care Unit, Murcia, Spain