The exhaled breath nitric oxide meter, which can identify the cause of chronic cough by measuring the level of nitric oxide in the patient’s exhaled breath, is a simple and reliable method that has relieved a large number of patients suffering from chronic cough since the introduction of this technology. Chronic cough: It is a cough that has been present for more than 8 weeks and no abnormalities are found on chest x-ray or CT examination. Causes of chronic cough: In China chronic cough causes are common: cough variant asthma croup acid bronchitis upper airway cough syndrome gastroesophageal reflux cough. Significance of monitoring exhaled breath nitric oxide: The instrument can measure the value of nitric oxide in the patient’s exhaled breath within a few tens of seconds, which can quickly determine whether the patient’s cough is cough variant asthma or eosinophilic bronchitis. Treatment options are provided.