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|Title:||Airway impedance entropy and exacerbations in severe asthma.|
E Brightling C
|Citation:||EUR RESPIR J, 2012|
|Abstract:||Variability of peak flow measurements has been related to clinical outcomes in asthma. We hypothesized that the entropy, or information content, of airway impedance over short time scales may predict asthma exacerbation frequency.Sixty-six patients with severe asthma and thirty healthy control subjects underwent impulse oscillometry at baseline, following a deep exhalation manoeuvre, and following bronchodilator administration. On each occasion, airway impedance parameters were measured at 0.2 second intervals for 150 seconds, yielding a time series, which was then subjected to Sample Entropy analysis.Airway impedance, and Sample Entropy of impedance, was increased in asthmatic patients compared to healthy controls. In a logistic regression model, Sample Entropy of R5-R20, a marker of the fluctuation of the heterogeneity of airway constriction over time, was the variable most strongly associated with the frequent exacerbation phenotype (odds ratio of 3.23 for every 0.1 increase in Sample Entropy).Increased airway impedance and Sample Entropy of impedance is associated with the frequent exacerbation phenotype. Prospective studies are required to assess their predictive value.|
|Appears in Collections:||Published Articles, Dept. of Infection, Immunity and Inflammation|
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