Table 2 Baseline variables for both severe and non-severe acidosis

pH

Patients

≤7.25

109

>7.25

131

≤7.25

219

>7.25

322

≤7.25

72

>7.25

117

≤7.25

399

>7.25

570

Age, years, X (SD)

76 (10)

75 (10)

71 (9)

70 (9)

72 (10)

70 (11)

73 (10)

71 (10)^**

Sex, male, %

40

44

88

86

49

29^**

61

46^***

BMI, X (SD)

33 (7)

30 (8)^*

26 (5)

29 (6)^***

37 (8)

40 (8)^**

30 (7)

32 (8)^**

Smoker, %

6.3

4.8

16

36^***

11

19

12

23^**

Drinker, %

3.2

6.5

6

12^*

9

9

5

9^*

Respiratory rate, X (SD)

25.4 (6.6)

25.3 (4.5)

25.8 (3.9)

25.6 (5.1)

24.6 (3.7)

23.5 (4.1)^*

25.5 (3.8)

25.1 (4.8)^*

Systolic BP, mmHg, X (SD)

133 (24)

135 (19)

133 (20)

134 (21)

143 (20)

129 (17)^***

135 (21.1)

133.3 (19.8)

Diastolic BP, mmHg, X (SD)

72 (17)

73 (14)

72 (10)

74 (12)^*

76 (10)

69 (11)^***

72.6 (12.2)

72.5 (12.5)

Charlson index, X (SD)

3.2 (1.3)

2.5 (1)^***

2.2 (1.2)

2.3 (1.1)

2.2 (1.5)

1.9 (0.9)

2.5 (1.4)

2.3 (1.1)^*

Glasgow scale, X (SD)

13.4 (1.6)

13.7 (1.9)^***

13.7 (1.1)

14 (1.1)^***

13.5 (1.9)

14 (1.3)^**

13.6 (1.4)

14 (1.4)^***

APACHE II score, X (SD)

20.7 (7.2)

19.1 (5.8)^*

19.7 (5.7)

18.7 (5.1)^**

18.3 (5.9)

17.4 (4.7)

19.7 (6.2)

18.5 (5.2)^**

PaO₂, mmHg, X (SD)

70 (28)

65 (32)^*

64 (35)

61 (22)

59 (17)

59 (24)

65 (31)

61 (25)

PaO₂/FiO₂, X (SD)

178 (82)

191 (97)

180 (103)

198 (76)^***

164 (62)

186 (80)^*

176 (92)

194 (82)^***

PaCO₂, mmHg, X (SD)

87 (22)

70 (15)^***

87 (21)

76 (14)^***

83 (17)

74 (14)^**

86 (21)

75 (14)^***

PH, X (SD)

7.18 (0.07)

7.30 (0.03)^***

7.19 (0.05)

7.30 (0.25)^***

7.19 (0.05)

7.30 (0.03)^***

7.18 (0.06)

7.30 (0.03)^***

FVC, %, X (SD)

60 (10)

62 (12)^*

FEV1, %, X (SD)

36 (9)

41 (10)^***

RICU type 1, %

78

57^**

62

59

58

43

66

55^**

PS mode, %

67

69

72

88^*

50

69^*

68

81^**

CPAP/NIV, %

11

22

17

24

38

27

19

24

DNI order, %

66

64

75

59^***

56

53

68

59^**