Exhaled nitric oxide in childhood asthma

Endogenous synthesis of nitric oxide (NO) and its presence in exhaled air was observed in various species including humans. Particularly high levels were found in adults with bronchial asthma, possibly because of the underlying pulmonary inflammatory activity. We studied oral and nasal exhaled NO by chemiluminescence in 47 children aged between 6 and 10 years. Thirty children had bronchial asthma, 17 were healthy controls. In asthmatic children oral exhaled NO was 13.4 +/- 1.4 parts per billion (ppb) (mean +/- SEM), nasal exhaled NO was 21.7 +/- 1.5 ppb. In healthy controls oral exhaled NO was 7.2 +/- 1.0 ppb, nasal exhaled NO was 18.2 +/- 2.2 ppb. Oral exhaled NO was significantly higher in asthmatic children compared to healthy controls (P = 0.0017). Nasal exhaled NO did not differ significantly in the two groups. There was a significant negative correlation between oral exhaled NO and forced expiratory volume in 1 s (FeV1). No significant correlation between oral or nasal exhaled NO and other markers of obstructive lung function impairment, oral minute ventilation, the body mass index and the presence of upper respiratory tract infection could be found. Conclusion Children with bronchial asthma have significantly higher levels of orally exhaled nitric oxide than healthy controls.