Table 2 Characteristics of the studied population: demographic data, diurnal and nocturnal gas exchanges and ventilator settings

Effective

25

29

46

100

 Anthropometric data

  Age (years)

70 [61–77]

71 [60–75]

50 [22–62]*^¶

62 [47–71]

  Gender (male/female)

16/9

12/17

31/15

59/41

  BMI (kg/m²)

39 [32.2–41.5]

40 [27.2–47.7]

22 [18.4–30.5]*

31.0 [21.6–40.4]

 Daytime arterial blood gases

  Daytime PaO₂ (mmHg)

66.5 [61.1–79.3]

65 [60.7–73]

78 [71–93]*^¶

71.3 [62.4–84]

  Daytime PaCO₂ (mmHg)

45 [41.9–49]

42 [39.3–47.8]

41 [38.5–44.2]*

41.9 [39.4–47]

 Nocturnal transcutaneous capnography

  Median SpO₂ (%)

90 [89–92.4]

92 [89.8–93.3]

95 [93.8–96]*

93 [90–95]

  Median TcPCO₂ (mmHg)

49 [44.2–53.2]

48 [43–52.4]

43 [40–47.3]*^¶

45.8 [41.9–50.1]

  Maximal TcPCO₂ (mmHg)

55 [49.5–64]

56 [52.5–59]

48 [44–53.5]*

52 [46–57]

  Recording time spent with TcPCO₂ > 50 mmHg

58 [1.96–89.9]

28 [3.3–81.5]

0 [0–28.2]*

6.7 [0–72.1]

 Ventilator settings

  Inspiratory pressure (cmH₂O)

19 [18–21]

18 [16–19]

16 [14–17]*^¶

17.5 [16–19]

  Expiratory pressure (cmH₂O)

8 [6–9]

9 [5–10]

6 [4–8]*^¶

6 [4–10]

  Interface: nasal/oronasal mask

12/13

13/16

28/18*^¶

53/47

  Compliance (h/day)

8.5 [7.5–10]

7.2 [5.8–9.7]

8 [6–9.4]

7.9 [6.1–9]