Table 2 Blood gases, respiratory pattern and systemic hemodynamic data

Blood gases

 PaO₂ (mmHg)

94 ± 21

94 ± 21

97 ± 21

94 ± 25

91 ± 25

94 ± 24

0.325

0.495

0.864

 PaCO₂ (mmHg)

38 ± 9

37 ± 8

36 ± 8

39 ± 10

39 ± 11

38 ± 9

<0.001

0.202

0.102

 SaO₂ (%)

97 ± 2

97 ± 1

98 ± 2

97 ± 2

97 ± 2

97 ± 2

0.174

0.309

0.782

 pH

7.41 ± 0.1

7.43 ± 0.1

7.45 ± 0.1

7.42 ± 0.1

7.43 ± 0.1

7.43 ± 0.1

<0.001

0.464

0.164

Base excess

0.2 ± 3.6

0.3 ± 3.6

0.1 ± 3.6

0.4 ± 3.5

0.5 ± 3.5

0.5 ± 3.5

0.194

0.244

0.592

Respiratory pattern

 Respiratory rate (breaths/minute)

21 ± 5

18 ± 4

13 ± 3

20 ± 5

21 ± 5

20 ± 6

<0.001

0.041

<0.001

 Tidal volume (ml/kg PBW)

6.3 ± 1.1

8.2 ± 1.8

11.4 ± 3.0

6.7 ± 1.2

7.0 ± 1.2

7.6 ± 1.2

<0.001

0.018

0.001

 Minute ventilation (l/minute)

7.7 ± 2.0

8.6 ± 2.5

8.7 ± 2.1

8.1 ± 2.7

8.6 ± 2.5

8.7 ± 3.0

<0.001

0.619

0.361

 Electrical activity of the diaphragm (% EAdi max)

61 ± 16

32 ± 11

17 ± 9

90 ± 33

71 ± 19

29 ± 25

<0.001

0.002

0.3

 Mean inspiratory transpulmonary pressure (cmH₂O)

3 ± 4

5 ± 4

10 ± 4

3 ± 3

3 ± 4

7 ± 5

<0.001

0.158

<0.001

 Mean esophageal pressure deflection (cmH₂O)

−0.7 ± 1.5

2.1 ± 1.9

4 ± 2.3

−1.5 ± 2.4

−1.5 ± 1.7

0 ± 1

0.001

<0.001

<0.001

Systemic hemodynamic data

 Pulmonary artery occlusion pressure (mmHg)

16 ± 7

14 ± 4

15 ± 7

15 ± 7

15 ± 5

16 ± 6

0.516

0.424

0.241

 Mean systemic arterial pressure (mmHg)

65 ± 8

61 ± 9

65 ± 9

65 ± 9

63 ± 9

63 ± 9

0.065

0.922

0.256

 Heart rate (beats/minute)

90 ± 9

90 ± 9

89 ± 9

89 ± 10

90 ± 10

88 ± 10

0.3

0.831

0.567

 Cardiac output (l/minute)

4.7 ± 0.9

4.8 ± 0.7

4.8 ± 0.7

5.2 ± 1.2

5.1 ± 1.1

5.1 ± 1.2

0.964

0.082

0.284

 Mixed venous oxygen saturation (%)

66 ± 7

64 ± 5

66 ± 9

63 ± 5

65 ± 7

62 ± 5

0.469

0.059

0.211