Ventilation inhomogeneity in alpha1-antitrypsin-deficient emphysema.
The slope of phase III of the single-breath nitrogen wash-out test (sbN2-test) measures ventilation inhomogeneity and, in smokers, is strongly associated with small airways pathology. The present authors aimed to study ventilation inhomogeneity in emphysema related to type Z alpha1-antitrypsin (AAT) and to assess its relationship with indices of parenchymal damage and airways obstruction. A total of 18 subjects, consisting of ex-smokers with type Z AAT and emphysema (confirmed by computed tomography scan), were studied in a cross-sectional design. Post-bronchodilation flow-volume curves and gas transfer parameters were measured; sbN2-test curves were obtained and the slope of phase III was determined. The mean value of the slope (4.6+/-1.3% N2 x L(-1)) was higher than reference values +2sd; it was significantly correlated with the transfer factor of the lung for carbon monoxide (R = -0.75) and the transfer coefficient of the lung for carbon monoxide (R = -0.58), but not with airways obstruction. There was no correlation between phase III slope values and cumulative smoking. In patients with type Z alpha1-antitrypsin emphysema, the increased ventilation inhomogeneity predominantly reflects parenchymal abnormalities, demonstrating that measurement of airways obstruction is not sufficient to characterise the disease. Determination of the sensitivity of the single-breath nitrogen wash-out test slope in detecting disease progression may give complementary information to spirometry.
Lung Function Laboratory, Dept of Pulmonology (C3-P), Leiden University Medical Centre, P.O. Box 9600, 2300 RC Leiden, The Netherlands. l.fregonese@lumc.nl
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L
Fregonese
H P A A
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van Veen
P J
PJ
Sterk
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J
Stolk
D000328:Adult; D001944:Breath Tests / Q000379:methods; D003430:Cross-Sectional Studies; D005260:Female; D030342:Genetic Diseases, Inborn / Q000235:genetics / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008168:Lung / Q000473:pathology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009584:Nitrogen / Q000032:analysis; D011656:Pulmonary Emphysema / Q000235:genetics / Q000473:pathology / Q000503:physiopathology*; D000515:alpha 1-Antitrypsin / Q000235:genetics*
D000515:alpha 1-Antitrypsin; D009584:Nitrogen