Table 1 Patient baseline characteristics^a

Age, yr, median (IQR)

58 (43 to 66)

56 (41 to 64)

0.332

Sex, n (%)

0.372

  Male

50 (52%)

59 (58%)

  Female

47 (48%)

43 (42%)

Ethnicity, n (%)

0.196

  Caucasian

59 (61%)

57 (56%)

  African American

33 (34%)

37 (36%)

  Other

3 (3%)

0 (0%)

  Not documented

2 (2%)

8 (8%)

Weight, kg, median (IQR)

83 (66 to 97)

86 (72 to 102)

0.153

Intensive care unit, n (%)

  Surgical/trauma

67 (69%)

61 (60%)

0.173

  Medical

30 (31%)

41 (40%)

Reason for ICU admission, n (%)

  Surgical

34 (35%)

43 (42%)

0.282

  Medical

36 (37%)

40 (39%)

  Trauma

27 (28%)

19 (19%)

APACHE II score,^b median (IQR)

21 (17–23)

19 (16–24)

0.800

Vasopressor at baseline, n (%)

53 (55%)

49 (48%)

0.352

Reason for mechanical ventilation, n (%)

  Postoperative

24 (25%)

17 (17%)

0.803

  Chest trauma

9 (9%)

6 (6%)

  Pneumonia

11 (11%)

11 (11%)

  Severe sepsis

21 (22%)

18 (18%)

  Cardiogenic pulmonary edema

3 (3%)

5 (5%)

  PE

2 (2%)

3 (3%)

  Asthma

6 (6%)

10 (10%)

  Cardiac arrest

1 (1%)

1 (1%)

  Airway protection

15 (15%)

22 (22%)

  ARDS

3 (3%)

6 (6%)

  Other

2 (2%)

3 (3%)

Past medical history, n (%)

  Hypertension

49 (51%)

54 (53%)

0.732

  Cardiac disease

29 (30%)

31 (30%)

0.939

  DM

20 (21%)

36 (35%)

0.021

  Asthma or COPD

24 (25%)

32 (31%)

0.299

  Malignancy

16 (16%)

17 (17%)

0.974

  End-stage renal disease

5 (5%)

6 (6%)

1.0

  Cirrhosis

2 (2%)

4 (4%)

0.684

Number of spontaneous breathing trials per patient, median (IQR)

3 (1 to 4)

2 (1 to 5)

0.870