TY - JOUR T1 - The relationship of small airways disease to spirometry and emphysema in α-1 antitrypsin deficiency JF - European Respiratory Journal JO - Eur Respir J VL - 44 IS - Suppl 58 SP - P3971 AU - Asem Ismail AU - James Stockley AU - Robert Stockley Y1 - 2014/09/01 UR - http://erj.ersjournals.com/content/44/Suppl_58/P3971.abstract N2 - 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. ER -