FO2 insp. and FO2 pre-insp. measurements
For all experimental conditions, the actual oxygen concentrations of FO2 insp. and FO2 pre-insp. with different lung conditions from our spontaneous breathing lung model are shown in Table 1. The data indicate that FO2 pre-insp. was higher than FO2 insp. under different conditions. With the same VT as normal lung mechanics, the measured FO2 insp. and FO2 pre-insp. decreased as the f increased. However, at the same f, a smaller FO2 insp. and FO2pre-insp. were recorded when a larger VT was present. The same outcomes were reported in the restricted and obstructed lung models.