Relationship between Exhaled Nitric Oxide Concentration and Pulmonary Function/Airway Hyperresponsiveness in Asthmatic Children

Purpose: Exhaled nitric oxide (eNO) has been proposed as a non-invasive marker for airway inflammation in asthma. Pulmonary function tests have been widely used in the diagnosis and management of asthma. Airway hyperresponsiveness (AHR) is one of the major features in asthma and usually assessed by the methacholine challenge test. The purpose of the present study was to assess the possible relationship between eNO and pulmonary function/AHR in asthmatic children. Methods: There were 121 asthmatic children and 81 controls in the study. The eNO level was measured, the methacholline challenge test, spirometry, impulse oscillometry (IOS) and assessment of their bronchodilator responses were performed on all subjects. Results: The asthma group had a higher eNO value than the control group [28.3 (15-55.75) vs. 20 (12.35-39.7) ppb, P=0.015]. The eNO level correlated positively with dFEV1 (r=0.230, P=0.001). It correlate inversely with dR5 (r=-0.149, P=0.036), eNO with PC20 (r=-0.318, P