Table 4. Partial Pressure of Arterial Carbon Dioxide; PCO₂ (mmHg).

Time	Study Group a				P value
	Total (n = 300)	CPAPb(n = 102)	IMVb(n = 95)	Control (n = 103)
Before intubation	32.06 ± 4.5	33.04 ± 4.3	32.86 ± 4.2	30.34 ± 4.3	< 0.001
Before CPBb	29.9 ± 6.04	30.85 ± 5.8	30.31 ± 6.8	28.62 ± 5.3	0.022
After CPB	33.6 ± 6.3	34.93 ± 6.8	33.61 ± 6.3	32.23 ± 5.5	0.037
ICU admission	33.6 ± 6.3	34.23 ± 7.0	33.84 ± 5.4	32.70 ± 6.2	0.198
4 hours afterextubation	34.9 ± 4.6	35.55 ± 4.7	34.78 ± 4.9	34.28 ± 4.0	0.103
12 hours afterextubation	34.9 ± 4.5	36.06 ± 4.6	34.11 ± 4.0	34.46 ± 4.6	0.001
24 hours afterextubation	34.72 ± 4.4	35.43 ± 4.2	34.68 ± 4.5	34.05 ± 4.4	0.079
48 hours afterextubation	34.5 ± 5.1	35.87 ± 6.3	34.46 ± 4.2	33.34 ± 4.2	0.002

^a Values are mean ± SD

^b Abbreviations :CPAP, continuous positive airway pressure; CPB, cardiopulmonary bypass; IMV, intermittent mandatory ventilation