Source: International Congress 2015 – Lung function: exploring the boundaries of the respiratory system
Disease area: Airway diseases

Abstract

Background: Tracheal forced expiratory (FE) noise time (FET_a) is a promising test of airway obstruction.Objective: To find new FE acoustic indexes for diagnostics.Methods: Spirometry, bodyplethismography and tracheal FE noise recording were performed in the sample of healthy nonsmokers (n=50, age Me;LQ;UQ – 25.0;21.0;30.0), obstructed patients including asthma (n =41, age 37.0;26.0;54.0, FEV₁% 90.5;81.7;96.1, FEV₁/FVC 70.1;65.4;75.8) and COPD (n=35, age 58.0;54.0;62.0, FEV₁% 71.8;50.5;88.1, FEV₁/FVC 58.7;48.7;64.6). FET_a in 200-2000 Hz band and 200-Hz band pass energy, normalized by total energy in 200-2000 Hz band – A_800-1000/A_200-2000, A_400-600/A_200-2000 were calculated.Results: The combination of FET_a > 2.26 s “or” A_800-1000/A_200-2000 > 0.117 provides discrimination of healthy and obstructed patients with efficiency 89%. The decision rule A_400-600/A_200-2000/FET_a = L = 0.075 divides patients into 2 clusters in the scatter plot. There are significant differences between the clusters in FEV₁%, FEV₁/FVC, R_tot%, RV%, RV/TLC%. Asthma subgroups in the clusters – 63.5% (L > 0.075) vs 36.5% (L < 0.075) – differ by FEV₁/FVC, R_tot%, RV/TLC, while COPD subgroups – 26% vs 74% – by FEV₁%, FEV₁/FVC. Lung function indexes under L < 0.075 correspond to increasing degree of airway obstruction. According to the acoustic reasons L < 0.075 condition is interpreted as a shift of FE maximal airway resistance to more distal bronchi. Higher functional indexes of lung hyperinflation support this speculation indirectly.Conclusion: Found acoustic indexes may be useful to characterize bronchial obstruction features.The study is supported by RFBR grant 14-04-0048.


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Irina Pochekutova (Vladivostok, Primorsky Krai, Russian Federation), Irina Pochekutova, Vladimir Korenbaum, Veronika Malaeva, Anatoly Kostiv, Valentina Kudryavtseva. The combination of forced expiratory tracheal noise time and band pass energy divides patients with bronchial obstruction into two clusters. Eur Respir J 2015; 46: Suppl. 59, 955

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