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S42 Correlation of measurement of small airways indices in a population of firefighters
  1. J Feary,
  2. T Kabir,
  3. S Schofield,
  4. P Cullinan
  1. London, UK


Background Small airways damage is a plausible response to fire smoke inhalation. In the UK, periodic respiratory health surveillance is carried out using spirometry. Previous studies have suggested the use of impulse oscillometry (IOS) may identify small airways dysfunction in firefighters even in the context of normal spirometry values and it is hypothesised that this may predict future development of asthma or COPD.

Methods We measured pre and post-bronchodilator spirometry and IOS using ERS/ATS guidelines on the first 203 individuals recruited to a cohort study of firefighters (Grenfell Firefighter Study). We defined significant bronchodilator response as 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.

Results The majority of individuals were male, with a mean age of 45 years; 140 (69%) had never smoked and 12 (6%) had a more than 20 pack year history of smoking. Overall, 32 (16%) had a history of asthma (ever), 15 (8%) had evidence of significant bronchodilator reversibility and 3 (2%) were taking asthma treatment. The majority (73%) reported no breathless (Dyspnoea-12 score of zero). The mean percentage 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 -0.22 (-0.35 to -0.08).

Abstract S42 Table 1

Demographics, respiratory symptoms and lung function

Conclusion We have measured high quality lung function on over 200 firefighters. Further work will be carried out on a larger population of firefighters to explore correlations between spirometry and other measures of small airways indices obtained using IOS to determine if small airways abnormalities are associated with age, sex, smoking and the presence of asthma or self-reported breathlessness. In the future, IOS may prove a useful tool to measure response to occupational fire smoke inhalation.

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