[1] Univ Florence, Dept Hlth Sci, Sect Anesthesiol & Intens Care, Largo Brambilla 3, I-50126 Florence, Italy
[2] Careggi Univ Hosp, Dept Anesthesiol, Florence, Italy
[3] Univ Washington, Harborview Med Ctr, Dept Med, Div Pulm & Crit Care, Seattle, WA 98104 USA