S42 Correlation of measurement of small airways indices in a population of firefighters

the use of impulse oscillometry (IOS) in of may on the first 203 individuals cohort of We significant bronchodilator response an improvement in forced expiratory volume in one second (FEV1) of 12% and 200mls following administration of inhaled bronchodilator. We also collected information on smoking and self-reported breathlessness using the Dyspnoea-12 questionnaire (maximum score of 36) and explored correlations between different measurements of small airways function. and year of Overall, 32 (16%) had a of asthma (ever), 15 (8%) had evi-dence of significant bronchodilator reversibility and 3 (2%) were taking asthma treatment. The majority (73%) reported no breathless (Dyspnoea-12 score of zero). The mean percent-age predicted pre-bronchodilator FEV1, forced vital capacity (FVC) and forced expiratory flow at 25 – 75% of FVC (FEF25 – 75) were 98%, 102% and 92% respectively using GLI reference equations. The correlation between FEF25 – 75 and frequency dependence of resistance (R5-R20) was (-0.35