The study was carried out in the respiratory and emergency
medicine units of Hospital of Lavagna and Sestri
Levante (Liguria, Italy) from September 2011 to December
2012. Each unit has 4 noninvasively monitored beds
and admits patients with severe respiratory failure who
need NIV. The study was carried out according to the
Helsinki Declaration and received the approval of the institutional
review committee; each subject gave written
informed consent.