[Exhaled and nasal nitric oxide in normal and asthmatic children]

Our aim was to study the concentration of nitric oxide in the exhaled (ENO) and nasal (NNO) air of normal children and asthmatic children who are clinically and functionally stable.

Using a nitric oxide chemiluminescence analyze and a register for CO2, pressure and flow, we studied 73 schoolchildren (6-17 years of age). This included 37 controls and 36 asthmatic children, 21 with mild asthma without antiinflammatory treatment and 15 treated with inhaled corticosteroids. We used the technique of slow exhalation against resistance for (ENO) determination and aspiration with stable flow in nasal cavity while holding the breath for (NNO) determination.

The mean ENO was 3.1 ppb (1-6) in the control group, 8.3 ppb (1.7-29.3) in the mild asthma group and 7.7 ppb (2-18.3) in the asthmatics treated with corticosteroids. There were significant differences (p = 0.0001) between the controls and both asthmatic groups. The mean NNO in the controls was 898 ppb and differences between this group and the asthmatic children were found. The ENO and NNO did not change in relation to age or sex. We did not find any relationship between ENO and lung function. There is a significant correlation between ENO and NNO in both asthmatic groups, but not in the control group.

The ENO was higher in asthmatics than in control children. The slow exhalation against resistance technique prevents the contamination of exhaled air with nasal air and this technique can be applied to children over 6 years of age. The NNO was similar in the asthmatic groups and the control group.