Variables and measurements
The main outcome variable of this study was FIO2, prior
to beginning the experiment, the oxygen analyzer was calibrated
according to the manufacturer’s instructions using 50 psi wall
oxygen and air source. Oxygen concentrations were recorded as
FO2 insp. and FO2 pre-insp., which are
defined as the peak inspiratory and pre-inspiratory phase, respectively
(Fig. 3). Oxygen concentrations measurements were obtained at
equilibrium, which was assumed to occur when the reading was steady over
the 3-min period. FO2 insp. and FO2pre-insp. were recorded for 10breaths and triplicate in each
experimental condition.