Changes in PaO2/FIO2 (A) and PaCO2 (B). Changes in PaO2/FIO2 (A) and PaCO2 (B). An FIO2 of 1.0 was used to calculate PaO2/FIO2 at the end of the apneic period just before intubation. Pre-ox = after 3 min of preoxygenation; Pre = 1 min after the induction of anesthesia, before intubation; Post = immediately after intubation, before mechanical ventilation; HFNC = high-flow nasal cannula oxygen therapy; BVM = bag-valve-mask ventilation. *, significant change between time points within group (P < .05). Marcel Simon et al. Respir Care 2016;61:1160-1167 (c) 2012 by Daedalus Enterprises, Inc.