Associations of AMP and adenosine induced dyspnea sensation to large and small airways dysfunction in asthma.

BACKGROUND: Bronchial provocation is often used to confirm asthma. Dyspnea sensation, however, associates poorly with the evoked drop in FEV1. Provocation tests only use the large airways parameter FEV1, although dyspnea is associated with both large- and small airways dysfunction. Aim of this study was to explore if adenosine 5'-monophosphate (AMP) and adenosine evoke an equal dyspnea sensation and if dyspnea associates better with large or small airways dysfunction. METHODS: We targeted large airways with AMP and small airways with dry powder adenosine in 59 asthmatic (ex)-smokers with ≥5 packyears, 14 ± 7 days apart. All subjects performed spirometry, impulse oscillometry (IOS), and Borg dyspnea score. In 36 subjects multiple breath nitrogen washout (MBNW) was additionally performed. We analyzed the association of the change (Δ) in Borg score with the change in large and small airways parameters, using univariate and multivariate linear regression analyses. MBNW was analyzed separately. RESULTS: Provocation with AMP and adenosine evoked similar levels of dyspnea. ΔFEV1 was not significantly associated with ΔBorg after either AMP or adenosine provocation, in both univariate and multivariate analyses. In multivariate linear regression, a decrease in FEF25-75 during adenosine provocation was independently associated with an increase in Borg. In the multivariate analyses for AMP provocation, no significant associations were found between ΔBorg and any large or small airways parameters. CONCLUSION: AMP and adenosine induce equally severe dyspnea sensations. Our results suggest that dyspnea induced with dry powder adenosine is related to small airways involvement, while neither large nor small airways dysfunction was associated with AMP-induced dyspnea. TRAIL REGISTRATION: NCT01741285 at www.clinicaltrials.gov , first registered Dec 4th, 2012.

Extrafine compared to non-extrafine particle inhaled corticosteroids in smokers and ex-smokers with asthma.

BACKGROUND: Smoking is as prevalent in asthmatics as in the general population. Asthmatic smokers benefit less from inhaled corticosteroids (ICS) than non-smoking asthmatics, possibly due to more smoking-induced small airways disease. Thus targeting small airways may be important in treating asthmatic (ex-)smokers. We hypothesized that extrafine particle ICS improve small airways function more than non-extrafine particle ICS in asthmatic (ex-)smokers. METHODS: We performed an open-label, randomized, three-way cross-over study comparing extrafine beclomethasone (HFA-QVAR) to non-extrafine beclomethasone (HFA-Clenil) and fluticasone (HFA-Flixotide) in 22 smokers and 21 ex-smokers with asthma (?5 packyears). RESULTS: Improvement from baseline in PD20 adenosine after using QVAR, Clenil or Flixotide was 1.04 ± 1.71, 1.09 ± 2.12 and 0.94 ± 1.97 doubling doses, mean ± standard deviation (SD), respectively. The change from baseline in R5-R20 at PD20 adenosine after using QVAR, Clenil or Flixotide was ?0.02 ± 0.27, 0.02 ± 0.21, and ?0.02 ± 0.31 kPa sL?1, mean ± SD, respectively. The change in PD20 adenosine and R5-R20 at PD20 adenosine were neither statistically significant different between QVAR and Clenil (p = 0.86 and p = 0.82) nor between QVAR and Flixotide (p = 0.50 and p = 0.96). CONCLUSION: Similar effectiveness in improving small airways function was found for extrafine and non-extrafine particle ICS treatment for asthmatic smokers and ex-smokers.