[Research progress in relationship between fractional exhaled nitric oxide and asthma in children].

Bronchial asthma is a heterogeneous disease that is characterized by airway hyperresponsiveness and chronic inflammation. It is often accompanied by reversible airflow obstruction. Current laboratory testing methods for the diagnosis of asthma in children mainly include lung ventilation function test. Due to the non-cooperation of children, it is very challenging to conduct lung ventilation function test for preschoolers. Lung function testing is an instantaneous indicator, which is influenced by the children's understanding ability and mental factors. In addition, it could not assess the severity of airway inflammation. Fractional exhaled nitric oxide (FeNO) is a noninvasive, simple, and objective indicator of airway inflammation and has gradually gained increased use in children in recent years. This review article introduces the source of FeNO, the reference value of FeNO in laboratory testing, and the progress in the application of FeNO in the diagnosis, prediction, and treatment of asthma in children of various ages.