TY - JOUR T1 - Impulse oscillometry for leukotriene D<sub>4</sub> inhalation challenge in asthma JF - Respiratory Care DO - 10.4187/respcare.02417 SP - respcare.02417 AU - Wei-jie Guan AU - Jin-ping Zheng AU - Yi Gao AU - Cai-yu Jiang AU - Xu Shi AU - Yan-qing Xie AU - Qing-xia Liu AU - Mei Jiang AU - Jia-ying An AU - Xin-xin Yu AU - Wen-ting Liu AU - Li-ping Zhong AU - Zhong-ping Wu AU - Nan-shan Zhong Y1 - 2013/05/28 UR - http://rc.rcjournal.com/content/early/2013/05/28/respcare.02417.abstract N2 - BACKGROUND: The significance of impulse oscillometry (IOS) parameters for bronchial provocation tests remains poorly defined. We aimed to investigate the positive threshold derived from the parameters and diagnostic power of IOS to asthma by using leukotriene D4 bronchial provocation test (LTD4-BPT). METHODS: Sixty-two patients with asthma and 21 healthy subjects were enrolled. The IOS was employed to perform LTD4-BPT followed by spirometry. The positive threshold was determined based on the cut-off point in receiver operation characteristic curve, by which the parameters of the highest diagnostic power were obtained. RESULTS: Of all IOS parameters, airway impedance at 5 Hz (Z5), resistance at 5 Hz (R5) and resonant frequency (Fres) were characterized by the highest diagnostic power (area under curve: 0.821, 0.815 and 0.806, respectively), with an increase of 57%, 43% and 63% corresponding to a 20% fall in FEV1, respectively. IOS indices yielded similar assay sensitivity and specificity with spirometry. The positive threshold of IOS, defined as either a 57% increase in Z5 or 63% increase in Fres for bronchial provocation test, yielded an assay accuracy of 0.6 in patients with asthma. CONCLUSIONS: IOS, when employed to conduct LTD4-BPT, is characterized by similar diagnostic power compared with spirometry. Either a 57% increase in Z5 or 63% increase in Fres may be regarded as a surrogate of FEV1 fall to determine airway hyperresponsiveness in asthma. ER -