Childhood asthma: exhaled nitric oxide in relation to clinical symptoms

Bronchial asthma is associated with increased levels of exhaled nitric oxid e which are suppressible by glucocorticosteroid inhalation. Children with b ronchial asthma were studied to elucidate the relation between endogenous N O release and recent symptoms of bronchial obstruction. Twenty-five children with atopic asthma and 11 healthy control subjects wer e enrolled and exhaled NO was studied using chemiluminescence analysis. The subjects breathed purified air (<0.5 parts per billion (ppb) NO) exclusive ly through their mouths. Orally expired NO was measured during continuous nasal aspiration (1.3 L mi n(-1)) to remove nasally produced NO. Nasal NO concentration was determined within the aspirated gas. Orally expired NO concentration was 2.5+/-0.3 pp b (mean+/-SEM) in healthy control subjects, 3.19+/-0.88 ppb (Ns) in symptom -free children, and 8.28+/-0.81 ppb (p less than or equal to 0.01) in child ren with bronchial asthma who had had recent symptoms of bronchial obstruct ion. Similarly, in the subgroup of children treated regularly with inhaled gluco-corticosteroids those with recent symptoms had significantly higher o rally exhaled NO concentrations than healthy control subjects (9.5+/-1.5 pp b, p<0.05). The nasal NO concentration was 152.8+/-12.7 ppb in healthy cont rol subjects and not significantly different in asthmatic children. In this group of asthmatic children, recent symptoms of bronchial obstructi on were linked to significantly higher concentrations of NO in orally exhal ed gas and to increased oral NO excretion rates. If substantiated by furthe r studies, measurement of orally exhaled NO during nasal aspiration may bec ome useful to monitor disease control in asthmatic children.