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Annals of Intensive Care

Table 1 Baseline patient characteristics according to the oxygenation strategy used after extubation

From: Non-invasive ventilation alternating with high-flow nasal oxygen versus high-flow nasal oxygen alone after extubation in COPD patients: a post hoc analysis of a randomized controlled trial

 

High-flow nasal oxygen alone (n = 64)

Non-invasive ventilation (n = 86)

p value

Characteristics of the patients at admission

 Age, years

66 ± 9

66 ± 9

0.900

 Male sex, n (%)

48 (75%)

61 (71%)

0.580

 Body mass index (BMI), kg/m2

27 ± 6

27 ± 7

0.875

 Obesity (BMI ≥ 30 kg/m2), n (%)

14 (22%)

25 (29%)

0.326

 COPD confirmed by spirometry, n (%)

43 (67%)

53 (62%)

0.483

 FEV1, % of predicted value

58 ± 18

57 ± 17

0.834

 Underlying chronic cardiac disease, n (%)

14 (22%)

28 (33%)

0.149

  Ischemic heart disease

9 (14%)

15 (17%)

0.577

  Atrial fibrillation

4 (6%)

9 (10%)

0.364

  Left ventricular dysfunction

5 (8%)

7 (8%)

0.942

 SAPS II at admission, points

53 ± 17

52 ± 18

0.874

 Main reason for intubation, n (%)

  Acute respiratory failure

43 (67%)

59 (69%)

0.099

  Coma

6 (9%)

10 (12%)

  Shock

9 (14%)

3 (3%)

  Cardiac arrest

4 (6%)

4 (5%)

  Surgery

2 (3%)

9 (10%)

  Other reasons

0 (0%)

1 (1%)

Characteristics of the patients on the day of extubation

 SOFA score, points

4.0 ± 2.5

3.8 ± 2.0

0.639

 Median duration of mechanical ventilation, days

5.5 [3.0–10.5]

6.5 [3.0–13.0]

0.504

 Difficult or prolonged weaning#, n (%)

20 (33%)

28 (32%)

0.865

 Ineffective cough, n/n total (%)

7/59 (12%)

26/82 (32%)

0.006

 Abundant secretions, n/n total (%)

31/60 (52%)

37/83 (45%)

0.402

 Administration of steroids before extubation, n (%)

12 (19%)

20 (23%)

0.505

Ventilator settings before the spontaneous breathing trial (SBT)

 Pressure support ventilation, n (%)

58 (91%)

75 (87%)

0.514

 Pressure support level, cm H2O

9.6 ± 2.5

9.6 ± 3.0

0.997

 Positive end-expiratory pressure, cm H2O

5.6 ± 1.7

6.0 ± 1.7

0.225

 Tidal volume, ml/kg

7.8 ± 2.2

7.9 ± 2.4

0.687

 Respiratory rate, breaths/min

23 ± 7

22 ± 6

0.767

 FiO2, %

34 ± 8

37 ± 13

0.228

 PaO2/FiO2, mm Hg

248 ± 70

247 ± 87

0.916

 pH, units

7.45 ± 0.05

7.44 ± 0.05

0.529

 PaCO2, mm Hg

44 ± 9

43 ± 8

0.373

 PaCO2 > 45 mm Hg, n (%)

26 (41%)

30 (35%)

0.542

Characteristics of the spontaneous breathing trial (SBT)

 Type of SBT, n (%)

  

0.807

 T-piece, n (%)

37 (58%)

48 (56%)

–

 Low level of pressure-support ventilation, n (%)

27 (42%)

38 (44%)

–

 Median duration of the SBT, min

60 [30–62]

60 [30–60]

0.432

 Respiratory rate at the end of SBT, breaths/min

24 ± 7

24 ± 6

0.782

 PaO2 at the end of SBT, mm Hg (n = 109)

78 ± 18

79 ± 22

0.735

 pH at the end of SBT, units (n = 109)

7.45 ± 0.05

7.46 ± 0.05

0.586

 PaCO2 at the end of SBT, mm Hg (n = 109)

44 ± 10

42 ± 9

0.398

 Hypercapnia at time of extubation‡, n (%)

22 (34%)

31 (36%)

0.832

  1. Italic means that there is a significant difference (p < 0.05)
  2. Continuous variables are given in mean ± standard deviation or median [interquartile range, IQR 25–75th percentiles] according to their distribution
  3. COPD chronic obstructive pulmonary disease, FEV1 forced expiratory volume during the first second (expressed in % of predicted value according to sex and age), SAPS Simplified Acute Physiology Score, SOFA Sepsis-Related Organ Failure Assessment, SBT Spontaneous Breathing Trial
  4. #Difficult or prolonged weaning refer to patient who failed the first spontaneous breathing trial and were not extubated the day of the first trial
  5. ‡Hypercapnia (defined as PaCO2 > 45 mm Hg) was assessed according to the PaCO2 level measured at the end of the spontaneous breathing trial (109 patients) or at the end of or under mechanical ventilation before the trial if this latter was not measured (41 patients)
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