PT  - JOURNAL ARTICLE
AU  - Asem Ismail
AU  - James Stockley
AU  - Robert Stockley
TI  - The relationship of small airways disease to spirometry and emphysema in α-1 antitrypsin deficiency
DP  - 2014 Sep 01
TA  - European Respiratory Journal
PG  - P3971
VI  - 44
IP  - Suppl 58
4099  - http://erj.ersjournals.com/content/44/Suppl_58/P3971.short
4100  - http://erj.ersjournals.com/content/44/Suppl_58/P3971.full
SO  - Eur Respir J2014 Sep 01; 44
AB  - BackgroundIt has been suggested that small airways disease precedes the development of basal emphysema in α-1 antitrypsin deficiency (AATD) 1. The present study assessed measures of small airway function, namely mean mid-expiratory flow between 25% and 75% of vital capacity (MMEF) in never smokers with AATD to determine the relationship to spirometry and CT densitometry.MethodsWe analysed percentage predicted values for MMEF and FEV1 as well as the FEV1:FVC ratio from 198 never smokers with ZZ AATD. The relationship of MMEF to lung densitometry was also assessed using a cut off of -910 HU to separate normal from emphysematous lungResultsCurvilinear relationships were observed between MMEF and FEV1, FEV1:FVC ratio (figure) and CT density. 20.2% of patients had a normal FEV1 (>80% predicted) and reduced MMEF (<80% predicted) whereas 33.8% of patients had normal FEV1:FVC (>70%) with reduced MMEF (Box-a). 10% of the patients had an abnormal MMEF when CT density was in the normal range.ConclusionThe results demonstrate that a reduced MMEF is often present in subjects whose spirometry is in the normal range and before demonstrable emphysema is present on CT scan. This supports the concept that small airways disease precedes the development of emphysema and MMEF is more sensitive to the presence of early disease than traditional spirometric measurements.1 Hogg JC et al. NEJM 350.26 (2004): 2645-653.