@article {Ioan3295, author = {Iulia Ioan and Silvia Varechova and Claude Bonabel and Thanh Le Tuan and Cyril Schweitzer and Fran{\c c}ois Marchal}, title = {Reversibility of airway obstruction to diagnose asthma in children using forced oscillations: Inspiration, expiration does it matter?}, volume = {40}, number = {Suppl 56}, elocation-id = {3295}, year = {2012}, publisher = {European Respiratory Society}, abstract = {Estimating reversibility of bronchial obstruction is part of the routine management of asthma. It is still not clear what forced oscillation technique (FOT) parameter response to salbutamol best differentiates asthmatics from controls.The aim of the study was to compare the ability to detect a different response to salbutamol between asthmatic and healthy children for the following parameters: respiratory resistance (Rrs), reactance (Xrs), impedance (Zrs) and admittance (Ars, the reciprocal of Zrs).Methods: 79 asthmatics and 20 controls aged 4 {\textendash} 11 y were included. FOT mesurements were obtained using a single sinusoidal pressure oscillation at 8 Hz. The parameters were computed separately in inspiration (I) and expiration (E). Reversibility was expressed as percentage from the corresponding baseline, except for Xrs {\textendash} frequently close to zero {\textendash} expressed as percentage of the baseline Zrs. The ability for each parameter to separate asthmatics from controls was tested at different decision levels by computing the Youden index (Y), a combination of sensitivity and specificity, that ranges from -1 for a useless test to +1 for maximal diagnostic value.Results. The response to salbutamol showed larger Y in I than E for Rrs (0.31 vs 0.25) and Ars (0.38 vs 0.35). In contrast, Y was equivalent in I and E for Zrs (0.3) and Xrs (0.11). The maximal Y value of 0.38 for Ars in I corresponded to 25\% increase after salbutamol.Conclusion. The diagnostic value of the FOT depends on breathing. Inspiration usually provides better discrimination. The information may be important to improve the diagnostic of asthma based on bronchial reversibility.}, issn = {0903-1936}, URL = {https://erj.ersjournals.com/content/40/Suppl_56/3295}, eprint = {https://erj.ersjournals.com/content/40/Suppl_56/3295.full.pdf}, journal = {European Respiratory Journal} }