RT Journal Article SR Electronic T1 The amount of endogenous particles in exhaled air is correlated to peripheral airway obstruction JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP P2052 VO 44 IS Suppl 58 A1 Emilia Viklund A1 Per Gustafsson A1 Sanna Kjellberg A1 Per Larsson A1 Anna-Carin Olin YR 2014 UL http://erj.ersjournals.com/content/44/Suppl_58/P2052.abstract AB Background: The peripheral airways, referred to as “the silent lung zone” when using spirometry, are involved especially in severe cases of clinical asthma. Obstruction of peripheral airways can be assessed with Inert Gas Washout (IGW)1 . The technique of sampling endogenous particles in exhaled air (PEx-Particles in Exhaled air) is a patient friendly method reflecting the chemical composition of the Respiratory Tract Lining Fluid (RTLF) in the peripheral airways2. The relationship between obstruction of peripheral airways and the amount of PEx has not previously been examined.We hypothesize that the amount of PEx will decrease with increasing peripheral obstruction.Methods: Forty eight subjects with asthma (22 females) performed multiple IGW, PEx, IOS and spirometry, post bronkodilatation.Results: PEx (pg/L) were not normally distributed, hence log transformation were used in statistical analysis. There was a statistically significant correlation between PEx and age (p<0,05), PEx and the small airway obstruction marker Sacin, assessed by IGW (p<0,05). No statistically significant correlation was seen between PEx and FEV1 % pred (p 0,29).Conclusions: The results support our hypothesis that obstruction of peripheral airways is related to the amount of PEx, that is the more peripheral obstruction, the less amount of PEx. Age is also an important variable in terms of amount of PEx. To chemically analyze the compounds in PEx from this study group is yet to be done.