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Table 3 Respiratory conditions and outcome according to severity of hypoxemia

From: Hypoxemia in the ICU: prevalence, treatment, and outcome

 

All hypoxemic patients, n = 859

Mild hypoxemia P/F 201–300 mmHg, n = 440

Moderate hypoxemia P/F 101–200 mmHg, n = 345

Severe hypoxemia P/F ≤ 100 mmHg, n = 74

p

Respiratory rate (n = 846/432/340/74)

23 [18–27]

22 [18–26]

24 [20–28]

25 [20–30]

0.001

Arterial blood gases

749 (87.2)

368 (83.6)

311 (90.1)

70 (94.6)

0.004

 pH (n = 745/366/309/70)

7.41 [7.36–7.46]

7.42 [7.38–7.45]

7.41 [7.36–7.46]

7.38 [7.29–7.45]

0.007

 PaCO2 (mmHg) (n = 749/368/311/70)

41 [36–49]

40 [35–46]

43 [38–55]

45 [39–56]

0.001

 PaCO2 > 45 mmHg (n = 749/368/311/70)

260 (34.7)

96 (26.1)

131 (42.1)

33 (47.1)

< 0.001

 PaO2 (mmHg) (n = 749/368/311/70)

78 [66–92]

84 [73–100]

74 [64–88]

65 [56–74]

< 0.001

 FiO2 (%) (n = 749/368/311/70)

0.40 [0.33–0.50]

0.35 [0.30–0.40]

0.50 [0.40–0.60]

1 [0.70–1]

< 0.001

 HCO3-(meq/L) (n = 747/368/309/70)

26 [23–30]

26 [22–29]

27 [23–32]

26 [23–30]

0.03

 Lactates (meq/L) (n = 630/312/257/61)

1.3 [1.0–1.9]

1.2 [0.9–1.7]

1.3 [1.0–1.9]

1.4 [1.1–2.7]

0.02

Oxygenation modalities, N (%)

    

< 0.001

 Ambient air

14 (1.6)

11 (2.5)

3 (0.9)

0 (0)

 

 Low-flow oxygen

191 (22.2)

136 (30.9)

55 (15.9)

0 (0)

 

 High-flow oxygen

45 (5.2)

11 (2.5)

23 (6.7)

11 (14.9)

 

 Non-invasive ventilation

84 (9.8)

43 (9.8)

33 (9.6)

8 (10.8)

 

 Invasive ventilation

525 (61.2)

239 (54.3)

231 (66.9)

55 (74.3)

 

Ventilator settingsa

     

 Tidal volume, mL/kg of ideal body weight; median IQR (n = 509/230/225/54)

6.9 [6.1–7.9]

7.1 [6.2–8.1]

6.8 [6.0–7.6]

6.1 [4.8–6.6]

< 0.001

 TV ≤ 8 mL/kg of ideal body weight (n = 509/230/225/54)

393 (77.2)

165 (71.7)

178 (79.1)

50 (92.6)

0.003

 PEEP (cmH20) (n = 519/236/229/54)

6 [5–10]

5 [5–8]

7 [5–10]

10 [8–12]

< 0.001

 Plateau pressureb (cmH20) (n = 186/66/84/36)

22.5 [19–27]

20 [16–24]

23.5 [20–28]

25.5 [23–29.5]

< 0.001

 Driving pressureb (cmH20) (n = 186/66/84/36)

14 [10–18]

13 [9–17]

14 [11–18]

13 [10–19]

0.31

Adjunctive therapies

     

 Prone positioning (n = 516/232/230/54)

22 (4.3)

3 (1.3)

13 (5.7)

6 (11.1)

0.001

 Inhaled NO (n = 513/233/226/54)

19 (3.7)

3 (1.3)

9 (4.0)

7 (13.0)

0.001

 Continuous intravenous sedation, N (%) (n = 522/237/231/54)

321 (61.5)

121 (51.1)

159 (68.8)

41 (75.9)

< 0.001

 Neuromuscular blocking agents, N (%) (n = 522/237/231/54)

83 (15.9)

11 (4.6)

44 (19.1)

28 (51.9)

< 0.001

 Extracorporeal oxygenation, N (%) (n = 522/237/231/54)

26 (3.0)

5 (1.1)

7 (2.0)

14 (18.9)

< 0.001

 ICU length of stay (days) (n = 840/431/336/73)

16 [7–32]

15 [7–32]

16 [8–31.5]

18 [7–37]

0.89

 ICU length of stay (days) in ICU survivors (n = 625/342/246/37)

15 [7–30]

15 [7–30]

14 [6.5–30]

20.5 [9–46.5]

0.27

 ICU mortality, N (%) (n = 839/431/335/73)

225 (26.7)

92 (21.3)

96 (28.5)

37 (50.7)

< 0.001

  1. aInvasively ventilated patients n = 525
  2. bOnly in patients in whom plateau pressure was measurable (i.e., patients in VAC without spontaneous breathing). n = 186