Effects of 30% vs. 60% inspired oxygen fraction during mechanical ventilation on postoperative atelectasis: a randomised controlled trial

Table 4 Secondary outcomes

Variables	30% FiO₂ group (n = 55)	60% FiO₂ group (n = 58)	P value
Over-aeration volume, %	9.40 (4.00, 14.30)	9.35 (3.95, 16.80)	0.629^b
Normal-aeration volume, %	78.00 (72.40, 85.50)	76.30 (69.88, 86.68)	0.389^b
Poor-aeration volume, %	6.50 (4.70, 9.00)	6.70 (4.55, 9.28)	0.966^b
Clinically significant atelectasis, n (%)	47 (85.5)	47 (81.0)	0.530^c
Oxygenation index, mmHg	414.92 ± 81.84	401.50 ± 99.16	0.423^a

Values are presented as mean ± SD, median (IQR), or n (%). P value refers to group comparison of the 30% FiO₂ group vs. 60% FiO₂ group by ^a two-sample t-test; ^b Mann-Whitney U test; ^c Chi-square test. FiO₂, inspired oxygen fraction

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