Table 3. Oxygenation index ($\overline{x}\pm s$) (mmHg).

Time	Group A (n=22)	Group C (n=31)	t	P
T1	189.0±65.4	366.3±56.8	−10.413	<0.001
T2	193.2±62.0	361.5±46.2	−10.992	<0.001
T3	130.8±40.5a	299.6±48.4a	−13.818	<0.001
T4	104.6±31.7b	248.7±48.0b	−10.924	<0.001

^a, oxygenation index at T₃ compared with T₁, P<0.001; ^b, oxygenation index at T₄ compared with T₁, P<0.001.