Diagnostic Value of Fractional Exhaled Nitric Oxide and Small Airway Function in Differentiating Cough-Variant Asthma from Typical Asthma.

To explore the diagnostic value of fractional exhaled nitric oxide (FeNO), small airway function, and a combined of both in differentiating cough-variant asthma (CVA) from typical asthma (TA). A total of 206 asthma subjects, including 104 CVA and 102 TA, were tested for pulmonary function, bronchial provocation test and FeNO. The correlation between FeNO, small airway function and other pulmonary indicators was analyzed by single correlation and multiple regression analysis. The receiver operating characteristic (ROC) curve was established to evaluate the diagnostic efficiency of FeNO, small airway function, and their combination and to predict the optimal cut-off point. All the respiratory function parameters and small airway function indicators in TA group were significantly different from those in CVA group, and FeNO value was significantly higher than that in CVA group. In addition, the area under the ROC curve (AUC) was estimated to be 0.660 for FeNO, 0.895 for MMEF75%/25%, 0.873 for FEF50%, 0.898 for FEF25%, 0.695 for Fres, 0.650 for R5-R20, and 0.645 for X5. The optimal cut-off points of FeNO, MMEF75%/25%, FEF50%, FEF25%, Fres, R5-R20 and X5, were 48.50 ppb, 60.02%, 63.46%, 45.26%, 16.63 Hz, 0.38 kPa·L-1·s-1, and -1.32, respectively. And the AUC of FeNO combined with small airway function indexes FEF25%, Fres, R5-R20, and X5 were prior than single indicators. FeNO and small airway function indexes might have great diagnostic value for differentiating CVA from TA. The combination of FeNO and FEF25%, Fres, R5-R20, and X5 provided a significantly better prediction than either alone.

Wang Y ，Zhao L ，Chen F ，Guo Y ，Ma H ，Han B ，Yi J ，Kong X ... -  《-》

Validity of fractional exhaled nitric oxide and small airway function indices in diagnosis of cough-variant asthma.

Feng-Jia C ，Xin-Yan H ，Geng-Peng L ，Yang-Li L ，Can-Mao X ... -  《-》

[Evaluating the efficacy of fractional exhaled nitric oxide and impulse oscillometry in screening out cough variant asthma from patients with subacute cough].

Fang S ，Chen SY ，He X ，Shen QX ，Fan HZ ，Wu XP ，Fang ZK ，Yu HP ... -  《-》

Asthma control in preschool children with small airway function as measured by IOS and fractional exhaled nitric oxide.

Zeng J ，Chen Z ，Hu Y ，Hu Q ，Zhong S ，Liao W ... -  《-》

Clinical features in patients of cough variant asthma with normal and high level of exhaled fractional nitric oxide.

Cough variant asthma (CVA) is a subtype of asthma that is characterized by a chronic cough. The clinical characteristics and pulmonary function in patients with CVA who had normal and high exhaled fractional nitric oxide (FeNO) levels were compared. The clinical history and pulmonary function data from 99 patients with newly diagnosed CVA were collected. Newly diagnosed subjects with CVA were divided into a high FeNO group (FeNO value over or equal to 25 ppb, n = 52) and a normal FeNO group (FeNO lower than 25 ppb, n = 47). There were more patients with coexistent allergic rhinitis or with family histories of allergic diseases in the high FeNO group. More patients in the high FeNO group reported that their chronic cough was triggered by allergen exposure. In the high FeNO group, the patients were younger than in the normal FeNO group. It was shown that baseline lung function tests were normal in all subjects, apart from a reduced midexpiratory flow rate (FEF25-75). There was a significant decrease in FEF25-75 in the high FeNO group compared with the normal FeNO group. No difference was found in the PD20 or the maximal FEV1 drop between the two groups. The multi-factor logistic regression analysis showed that concomitant with allergic rhinitis was the high risk factor of a high FeNO in these subjects with CVA (OR = 5.03, 95% CI, 1.88-13.49). CVA patients showed heterogeneity according to FeNO level. Patients with high FeNO level are more likely to experience symptoms associated with allergies.

Tang W ，Zhou J ，Miao L ，Shi G ... -  《-》