Studying the Role of Alveolar Exhaled Nitric Oxide in Combination with Bronchial Nitric Oxide to Predict Asthma Control in Children with Asthma: A Real-Life Prospective Study

Background: Fractional Exhaled Nitric Oxide (FENO) is currently used as a biomarker of airway inflammation in patients with asthma. However, the role of alveolar nitric oxide (CANO) in asthmatic children has not been clearly demonstrated. Methods: It was a prospective and descriptive study. The measurement of FENO and CANO, spirometry, blood eosinophil counts (BEC), and total IgE levels were performed for each study subject. Results: This study included 109 uncontrolled asthmatic children without inhaled corticosteroid (ICS) treatment. The exhaled NO level in asthmatic patients was significantly higher than in control subjects: FENO: 22.5 vs. 8.4 ppb; CANO: 5.9 vs. 2.8 ppb; J’awNO (maximum airway nitric oxide flux): 56.9 vs. 18.7 ppb; respectively. The sensitivities and specificities for asthma diagnosis with the cut-off of CANO at 3.5 ppb and 5.0 ppb were 74.3% and 73.3%, and 46.0% and 83.3%, respectively. There were the moderate and the weak correlations between CANO with FENO and CANO with IgE in asthmatic patients (r = 0.465, 95%CI (0.133-0.659), P=0.001; r=0.133, 95%CI (0.068- 0.497), P=0.184; respectively). The percentage of controlled asthma in patients with CANO ≥5 ppb at inclusion was higher than that in CANO <5 ppb group. Conclusion: Exhaled NO is a relevant biomarker of allergic asthma. The level of FENO and CANO might be used to predict asthma control in children.