Table 3 Long-term variability of spirometry and IOS parameters in degree of airway obstruction of stable COPD

SDbv

 FVC, L

0.25 (0.16–0.35)

0.17 (0.07–0.24) ^b

0.29 (0.17–0.36)

0.30 (0.22–0.45)

 FEV1, L

0.15 (0.09–0.22)

0.12 (0.06–0.17)

0.17 (0.10–0.23)

0.14 (0.10–0.20)

 MEF 50, L/s

0.10 (0.06–0.19)

0.15 (0.07–0.22)

0.11 (0.05–0.19)

0.09 (0.05–0.13)

 MEF 25, L/s

0.04 (0.02–0.08)

0.05 (0.03–0.08)

0.04 (0.02–0.05)

0.04 (0.02–0.06)

 MMEF 75/25, L/s

0.08 (0.05–0.13)

0.11 (0.07–0.13)

0.07 (0.04–0.13)

0.07 (0.05–0.10)

 R5, cmH₂O/(L/s)

0.86 (0.52–1.28)

0.66 (0.45–1.12)

1.18 (0.86–1.49) ^c

0.59 (2.27–0.99)

 R20, cmH₂O/(L/s)

0.40 (0.29–0.61)

0.39 (0.27–0.62)

0.49 (0.37–0.82)

0.33 (0.30–0.48)

 R5-R20, cmH₂O/(L/s)

0.71 (0.45–1.16)

0.58 (0.42–0.92)

0.95 (0.57–1.27)

0.51 (0.42–1.00)

 AX, cmH₂O/L

12.33 (6.88–19.30)

5.72 (3.29–10.29) ^{a b}

16.48 (11.97–24.07)

14.23 (8.31–19.78)

 Freq, 1/s

3.88 (2.33–6.59)

3.13 (1.94–5.07)

8.65 (6.54–14.83)

8.05 (4.18–11.47)

 X5, cmH₂O/(L/s)

1.46 (0.62–2.47)

0.47 (0.36–1.18) ^{a b}

1.93 (0.99–2.81)

1.93 (1.20–2.70)

COV

 FVC, L

11% (6–16%)

6% (3–10%) ^{a b}

12% (9–15%)

15% (10–21%)

 FEV1, L

15% (8–20%)

7% (3–15%) ^{a b}

17% (10–23)

17% (12–26%)

 MEF 50, L/s

20% (10–31%)

17% (8–22%)

24% (11–38%)

24% (16–35%)

 MEF 25, L/s

18% (11–28%)

16% (10–30%)

16% (12–27%)

23% (12–29%)

 MMEF 75/25, L/s

17% (12–25%)

17% (12–19%)

21% (11–32%)

20% (16–34%)

 R5, cmH₂O/(L/s)

15% (10–21%)

17% (10–21%)

17% (12–25%) c

10% (3–18%)

 R20, cmH₂O/(L/s)

13% (10–19%)

12% (10–17%)

16% (11–22%)

13% (9–16%)

 R5-R20, cmH₂O/(L/s)

29% (20–45%)

45% (26–59%)

32% (22–43%) ^{b c}

21% (9–29%)

 AX, cmH₂O/L

37% (24–56%)

39% (24–62%)

41% (24–60%)

32% (18–48%)

 Freq, 1/s

15% (9–23%)

16% (9–25%)

16% (11–25%)

13% (7–18%)

 X5, cmH₂O/(L/s)

37% (22–52%)

23% (17–47%) ^a

43% (27–66%)

31% (27–45%)

ICC

 FVC, L

0.96

0.98

0.92

0.79

 FEV1, L

0.94

0.96

0.79

0.68

 MEF 50, L/s

0.94

0.93

0.76

0.66

 MEF 25, L/s

0.84

0.88

0.34

0.37

 MMEF 75/25, L/s

0.94

0.95

0.75

0.67

 R5, cmH₂O/(L/s)

0.90

0.85

0.90

0.90

 R20, cmH₂O/(L/s)

0.84

0.79

0.83

0.85

 R5-R20, cmH₂O/(L/s)

0.84

0.77

0.80

0.84

 AX, cmH₂O/L

0.85

0.77

0.81

0.73

 Freq, 1/s

0.78

0.71

0.65

0.71

 X5, cmH₂O/(L/s)

0.78

0.80

0.75

0.34

COR

 FVC, L

0.71 (25%)

0.64 (19%)

0.72 (35%)

0.75 (50%)

 FEV1, L

0.45 (23%)

0.44 (21%)

0.49 (43%)

0.38 (49%)

 MEF 50, L/s

0.40 (26%)

0.50 (29%)

0.39 (49%)

0.27 (54%)

 MEF 25, L/s

0.18 (45%)

0.20 (39%)

0.18 (83%)

0.15 (83%)

 MMEF 75/25, L/s

0.31 (28%)

0.37 (29%)

0.31 (51%)

0.21 (58%)

 R5, cmH₂O/(L/s)

2.73 (35%)

2.42 (44%)

3.21 (36%)

2.17 (34%)

 R20, cmH2O/(L/s)

1.62 (47%)

1.38 (50%)

1.97 (50%)

1.13 (42%)

 R5-R20, cmH₂O/(L/s)

2.54 (46%)

2.33 (60%)

2.92 (51%)

2.17 (47%)

 AX, cmH₂O/L

44.35 (42%)

29.76 (63%)

49.94 (45%)

49.16 (53%)

 Freq, 1/s

15.05 (50%)

12.27 (56%)

17.21 (60%)

13.00 (52%)

 X5, cmH₂O/(L/s)

5.08 (47%)

2.78 (56%)

5.59 (46%)

5.89 (74%)