Table 2

- Comparison of in-group and between-group fraction of expired oxygen values.

TimeGroup 1 n (33)Group 2 n (33)P-value*
Mean±SDMedian (min–max)Mean±SDMedian (min–max)
T191.97±3.592 (81–97)c93.85±4.6795 (82–99)b0.012
T290.33±5.4292 (74–97)c90.24±5.4191 (78–98)b0.908
T358.94±5.5260 (49–69)b57.15±4.3658 (49–64)a0.081
T455.39±4.7758 (46–60)a55.18±4.1857 (46–60)a0.287

Group 1: 3 min at normal tidal volume, Group 2: 30 s with the 4 deep vital capacity technique. SD: standard deviation, Min: minimum, Max: maximum, T1: after preoxygenation, T2: immediately after intubation, T3: at the 3rd min after intubation, T4: at the 7th min after intubation, *P-value: Comparison between groups. P-value: Compared within the group, a-c: There is no difference between times with the same letter in a group.