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Table 2 Comparison of traditional pulmonary function tests and pulsed oscillatory resistance determination between the carbon dioxide retention and non-carbon dioxide retention COPD

From: The features of AECOPD with carbon dioxide retention

 

Carbon dioxide retention (n = 86)

Non-carbon dioxide retention (n = 144)

p value

Z5%pred

185.9 (154–216.65)

162.4 (131.35–199.6)

0.004

R5%pred

168 (138.85–197.7)

148 (126.75–182.75)

0.008

R5

0.52 (0.43–0.61)

0.49 (0.39–0.57)

0.057

R20%pred

123.4 (105.75–139.55)

117.2 (104.3–135.6)

0.236

R20

0.32 (0.29–0.375)

0.33 (0.29–0.37)

0.764

R5-R20

0.18 (0.125–0.23)

0.14 (0.09–0.205)

0.009

X5

−0.24 (−0.31--0.16)

−0.19 (− 0.32--0.13)

0.022

Fres

22 (18.26–26.19)

21.2 (17.48–24.61)

0.173

Ax

1.89 (1.27–2.57)

1.54 (0.74–2.44)

0.011

FEV1

0.95 (0.77–1.42)

1.39 (1.06–1.74)

< 0.001

FEV1%pred

34.25 (25.4–47.8)

51.45 (40–61.7)

< 0.001

FEV1/FVC

48.14 (42.08–56.71)

56.26 (46.55–62.79)

< 0.001

MMEF75–25%pred

14.25 (9.7–19.9)

21.5 (16.1–27.75)

< 0.001

DLCO/VA

75.47 ± 24.29

80.13 ± 24.34

0.169

RV/TLC

59.44 ± 10.11

55.98 ± 10.63

0.017

  1. Abbreviations: PFT Pulmonary function test, FEV1 forced expiratory volume in 1 sec, FVC forced vital capacity, FEV1/FVC forced expiratory volume in 1 sec/forced vital capacity, MMEF25–75% maximal mid expiratory flow, RV/TLC residual volume/total lung capacity, DLCO/VA ratio of carbon monoxide diffusion capacity to alveolar ventilation, %Pred, of the predicted value, Z5 Total respiratory impedance, R5 resistance at 5 Hz, R20 resistance at 20 Hz, X5 reactance at 5 Hz, Fres response frequency, Ax reactance area