Table 1 Baseline characteristics

Age (years)

59.0 [43.0, 71.0]

69.00 [52.0, 76.5]

56.0 [39.0, 67.0]

Male—N (%)

127 (62.9)

38 (60)

89 (64)

APACHE II^a

19.0 [15.0, 23.0]

21.0 [17.0, 24.0]

18.0 [15.0, 23.0]

Non-respiratory SOFA score

8.00 [5.00, 10.0]

8.00 [7.0, 11.0]

7.0 [4.0, 9.5]

Admission source–N (%)

Emergency

145 (71.8)

46 (73)

99 (71)

Elective

11 (5.4)

3 (4.8)

8 (6)

Medical

89 (44.1)

27 (43)

62 (45)

Surgical

71 (35.1)

26 (41)

45 (32)

ARDS severity—N (%)

Mild

78 (38.6)

25 (39.7)

53 (38.1)

Moderate

90 (44.6)

29 (46.0)

61 (43.9)

Severe

34 (16.8)

9 (14.3)

25 (18.0)

ARDS risk factor—N (%)

Trauma

36 (17.8)

8 (13)

28 (20)

Pneumonia

140 (69.3)

44 (70)

96 (69)

Non-pulmonary sepsis

36 (17.8)

14 (22)

22 (16)

Oxygenation parameters

PaO₂ (kPa) {mmHg}

11.1 [9.7, 13.5]

11.6 [10.0, 14.1]

11.0 [9.5, 12.8]

{83.3 [72.8, 101.3]}

{87 [75, 105.8]}

{82.5 [71.3, 96.0]}

FiO₂

0.5 [0.4, 0.8]

0.5 [0.4, 0.7]

0.5 [0.4, 0.8]

P/F ratio (kPa) {mmHg}

23.9 [16.2, 31.0]

24.7 [18.2, 34.2]

23.5 [15.4, 30.0]

{179.3,[121.5, 232.5]}

{185.3 [136.5, 256.5]}

{176.3 [115.5, 225.0]}

SaO₂ (%)^b

97.4 [95.5, 98.5]

97.7 [96.0, 98.8]

97.3 [95.3, 98.2]

Ventilation parameters

Tidal volume (ml/kg PBW)

7.1 [6.3, 8.4]

7.3 [6.4, 8.6]

7.1 [6.3, 8.3]

PEEP (cmH₂O)

8.0 [5.0, 10.0]

7.0 [5.0, 8.0]

8.0 [5.0, 10.0]

Mean airway pressure (cmH₂O)^d

13.0 [9.0, 16.0]

13.0 [9.0, 15.0]

12.0 [10.0, 16.0]

Lactate (mmol/L)

1.2 [0.8, 1.8]

1.4 [1.0, 2.0]

1.1 [0.8, 1.6]

Vasopressor use—N (%)*

114 (56.4)

41 (65)

73 (52)

Adjunctive therapies^#

Neuromuscular blockade—N (%)

62 (30.7)

14 (22)

48 (35)

Nitric oxide—N (%)

25 (12.4)

9 (14)

16 (11)

Prone positioning—N (%)

14 (6.9)

5 (8)

9 (6)