Table 1 Characteristics of the 339 patients with severe acute respiratory distress syndrome

Age, mean ± SD

60 ± 14

57 ± 16

0.10

Males, n (%)

79 (81%)

159 (66%)

0.009

Tidal volume (ml/kg predicted body weight), mean ± SD^a

6.34 ± 0.95

6.59 ± 1.1

0.04

Minute ventilation (liters/minute), mean ± SD^a

10.4 ± 2.4

9.9 ± 2.3

0.06

PEEP applied (cm of water), mean ± SD^a

9.2 ± 3.3

9.2 ± 3.4

0.97

Plateau pressure (cm of water), mean ± SD^a

25.4 ± 4.8

24.4 ± 4.8

0.11

Respiratory system compliance (ml/cm of water), mean ± SD^a

30.2 ± 9.7

32.0 ± 11.1

0.15

FiO₂, mean ± SD^a

0.77 ± 0.19

0.79 ± 0.19

0.43

pH, mean ± SD^a

7.31 ± 0.10

7.32 ± 0.10

0.73

PaO₂:FiO₂, mean ± SD^a

106 ± 33

111 ± 40

0.24

PaCO₂ (mm Hg), mean ± SD^a

47 ± 11

47 ± 11

0.66

SAPS II on admission, mean ± SD

50 ± 15

47 ± 15

0.19

SOFA on admission, mean ± SD

9.3 ± 3.8

9.3 ± 3.7

0.99

Glasgow Coma Scale score on admission, mean ± SD

10.9 ± 4.9

11.8 ± 4.2

0.08

Karnofsky score, mean ± SD

86 ± 14

88 ± 16

0.43

McCabe nonfatal, n (%)

74 (76%)

184 (76%)

0.99

Patients with immunodepression, n (%)

No

85 (87%)

192 (80%)

0.13

Chemotherapy

2 (2%)

20 (8%)

Long-term corticosteroids

4 (4%)

18 (7%)

HIV

2 (4%)

0 (0)

Other

3 (3%)

11 (5%)

Main reason for ICU admission, n (%)

Medical

68 (68%)

174 (72%)

0.60

Surgical emergency

18 (18%)

40 (17%)

0.75

Scheduled surgery

12 (12%)

27 (11%)

0.85

Corticosteroids for septic shock, n (%)^a

40 (40%)

103 (43%)

0.81

Four radiologic quadrants involved, n (%)^a

80 (82%)

196 (81%)

0.75

Direct lung injury, n (%)^a

79 (81%)

186 (77%)

0.56

Primary cause of ARDS, n (%)^a

NS

Community-acquired pneumonia

33 (34)

97 (40)

Nosocomial pneumonia

21 (21)

36 (15)

Ventilator-associated pneumonia

6 (6)

8 (3)

Aspiration pneumonia

18 (18)

44 (18)

Lung contusion

2 (2)

2 (1)

Near-drowning

1 (1)

1 (0.5)

Smoke inhalation

0 (0)

1 (0.5)

Intraabdominal sepsis

7 (7)

23 (10)

Sepsis other

3 (3)

10 (4)

Acute pancreatitis

3 (3)

7 (3)

Multiple transfusion

3 (3)

3 (1)

Multiple trauma

2 (2)

2 (1)

Shock

5 (5)

11 (5)

Other

5 (5)

10 (4)