Table 1 Characteristics of the study population of N = 312 mechanically ventilated children. Data are presented as median (25–75 interquartile range) or percentage (%) of total. Ventilator-free days (VFD) through day 28 were defined as the number of days within 28 days that a patient was alive and free of mechanical ventilation [16]. Patients were assigned 0 VFD if they remained intubated or died prior to day 28 without remaining extubated for more than 24 h. *Denotes p < 0.005 (Kruskal Wallis test). PRISM Pediatric Risk of Mortality; OI oxygenation index

 Age (months) *

49.3 (9.4–122.0)

23.1 (8.0–46.0)

2.0 (1.2–8.5)

2.2 (0.5–6.7)

  ≤ 12 months (%)

29.78

39.1

84.6

84.0

  13–60 months (%)

20.2

34.8

11.5

6.2

  > 60 months (%)

50.0

26.1

3.8

9.9

 Male gender (%)

61.9

58.0

62.8

63.0

 Weight (kg) *

16.5 (8.0–29.5)

12.4 (8.5–17.5)

5.0 (4.0–6.7)

4.2 (3.6–6.9)

 PRISM III 24 h score

8.5 (5.0–14.0)

10.0 (6.0–15.0)

11.0 (8.0–15.0)

12.0 (7.0–15.5)

 PARDS (%)

0.0

5.8

24.4

1.2

 Cstat (cmH₂O/L/kg) *

0.59 (0.43–0.78)

0.55 (0.39–0.73)

0.34 (0.28–0.44)

0.5 (0.32–0.6)

 PIP (cmH₂O) *

18 (16–22)

20 (17–23)

27 (24–29)

20 (18–23)

 Pplat (cmH₂O) *

16 (14–19)

17 (15–21)

24 (21–26)

18 (16–21)

 PEEP (cmH₂O) *

5 (5–6)

5 (5–6)

6 (5–7)

5 (5–6)

 Vt-exp (mL/kg) *

7.6 (6.6–8.6)

7.6 (6.5–8.5)

6.6 (6.1–7.7)

7.5 (6.8–8.3)

 Inspiratory time (s) *

0.75 (0.62–0.9)

0.7 (0.6–0.75)

0.55 (0.5–0.6)

0.55 (0.5–0.6)

 Mandatory breath rate (/min) *

22 (17–30)

23 (20–30)

40 (32–40)

35 (29–40)

 Ventilation time (h) *

88.3 (42.5–163.4)

69.8 (25.3–179.3)

107.5 (78.0–152.2)

91.5 (32.6–163.1)

 VFD day 28

24 (20–26)

24 (19–26)

23 (21–24)

24 (21–26)

PICU mortality (%)

6.0

4.3

2.6

3.7