The effect of bronchodilation and spirometry on exhaled nitric oxide

Background: Exhaled nitric oxide (NΟ) is usually measured before spirometry, either with or without bronchodilation. Aim: The aim of our study was to investigate the effect of bronchodilation and spirometry on Alveolar NO (Calv), Bronchial NO (JNO) and Fractional Exhaled NO (FeNO) in children and young adults with well-controlled asthma and in healthy volunteers. Methods: Fractional Exhaled NO (FeNO) was measured in 62 controls and 37 patients with asthma. Alveolar NO (Calv) and bronchial NO (JNO) were assessed in 35 and 10 of the healthy and asthmatic subjects respectively. All NO measurements were performed before spirometry (1), right after spirometry (2) 20 minutes after the first spirometry and bronchodilation and before the second spirometry (3) right after the post bronchodilation spirometry (4) and 30 minutes after the last spirometry (5). Results: The mean FeNO measurements (1-5) for the asthmatic and control group were (19.2±21.6, 19.1±21, 18.8±21, 18.2±20.4, 19.2 ±21.9 ppb, p=0.99) and (19.3±14.3, 19.6±14.5, 19.2±13.6, 18.7±13.2, 21.4 ±14.8 ppb, p=0.87) respectively. The mean Calv measurements (1-5) for the asthmatic and control group were (4.8±2.2, 3.4±1.6, 2.8±2.2, 3.3±1.3, 2.1 ±0.8 ppb, p=0.1) and (4.4±2.6, 3.8±2.2, 3.1±2, 3.2±1.6, 3.5 ±1.8 ppb, p=0.12) respectively. The mean JNO (1-5) for the asthmatic and control group was (1984±2008, 1947±1986, 2094±1881, 1888±1695, 2275 ±1796 pl/s, p=0.1) and (2009±2912, 1632±989, 1720±997, 1712±1107, 1665 ±969 pl/s, p=0.98) Conclusion: Spirometry, bronchodilation have an insignificant effect on FENO, JNO and Calv of patients with well-controlled asthma and healthy subjects. Therefore, FENO, JNO and Calv can be also measured after spirometry or bronchodilation.