Eucapnic voluntary hyperventilation test decreases exhaled nitric oxide level in children.

Abstract

Exhaled nitric oxide (FeNO) measurements and eucapnic voluntary hyperventilation (EVH) tests have been used as diagnostic tools for asthma. Data on the impact of hyperventilation on the level of FeNO are limited. We aimed to evaluate whether EVH tests affect the level of FeNO in children aged 10-16years. A total of 234 children aged 10-16years had a 6-min EVH test performed. In total, FeNO values for 153 of 234 children were measured before the test and within 15min after the test. According to a baseline FeNO level of 20ppb, children were divided into two groups: those with low values (FeNO<20ppb) and those with high values (FeNO≥20ppb). The median age of the children was 13.4years (interquartile range 12.3-15.3years); 58% were boys and 42% were girls. Of these children, 51% were sensitized to aeroallergens. In 101 of 153 children (66%), the FeNO values decreased after the EVH test. In children with low and high baseline levels, the median level of FeNO decreased after the EVH test: 10.5ppb before versus 9.5ppb after (p<.011), and 31.0ppb before versus 28.0ppb after (p<.011), respectively. The decrease in FeNO after EVH test was not associated with induced bronchoconstriction expressed as a change in FEV1 (Rs =.19). The EVH test decreases FeNO levels. Therefore, FeNO should be measured before an EVH test is performed.