Exhaled Nitric Oxide in Acute Phase of Bronchiolitis and Its Relation with Episodes of Subsequent Wheezing in Children of Preschool Age

Abstract

Background: Fractional exhaled nitric oxide (FENO) levels are increased in children with asthma and in infants with recurrent wheezing, but the role of FENO in the acute phase of bronchiolitis is still not defined. Objective: The aim of this study is to evaluate FENO values in the acute phase of bronchiolitis, compare them with healthy infants, and relate those values with the appearance of other wheezing episodes. Methods: FENO values were determined in infants between 2 months and 2 years affected with RVS bronchiolitis by offline method. The FENO values collected in the acute phase were related with the respiratory clinical symptoms presented in the 2 years following the episode. Results: A total of 30 patients were recruited: 15 in the bronchiolitis group and 15 in the control group. The average of the FENO values in the acute phase was 18.74 ppb (range 2-88) in the bronchiolitis group, and 8.75 ppb (range 2-24) in the control group. However, these results showed no significant statistical differences ( p = 0.176). Nevertheless, we found a positive correlation between the FENO values and the clinical score (Downes) of the bronchiolitis episode ( p = 0.023). In infants that presented other wheezing episodes in the 2 years after, the average of FENO in the acute phase of the first episode was 23.1 ppb (average of 10.25 ppb) versus 8.4 ppb (average 5.4 ppb) in the group of patients with no other episodes. The comparison of averages has no statistical significance. Conclusion: We found no differences in FENO between infants with bronchiolitis and healthy ones. The FENO values in the acute phase seems to be related to the severity of the disease but do not predict the appearance of wheezing episodes in the following 2 years.

Feasibility of multiple breath washout measurements in infants with bronchiolitis: A pilot study

“…Exhaled NO is raised in asthma, but findings are controversial regarding acute bronchiolitis. Levels were unchanged in one study, but were decreased in another compared to healthy controls or infants with recurrent wheezing, normalizing during convalescence . Our findings support the latter study.…”

“…Low eNO was found in infants with acute wheezy bronchitis, returning to normal following convalescence . However, in a subgroup of infants with subsequent wheezing illnesses, eNO was higher, possibly suggestive of future asthma …”

Fractional Exhaled Nitric Oxide: Indications and Interpretation

“…These findings suggest possible downregulation of NO production, impaired NO diffusion into the airway due to epithelial damage and increased airway secretions, and an inflammatory reaction mostly related to neutrophils. However, a more recent study in children with respiratory syncytial virus bronchiolitis shows FE NO higher (but without statistical significance) than healthy control during the acute phase of illness, and a positive correlation between FE NO and the clinical score (Downes) of bronchiolitis is noted with higher FE NO in children with more distress [132]. The inconsistency of the effect of viral infection on FE NO level is not fully explained but the differences in method, sample size, gender, atopy, allergy, asthma of study subjects, maternal smoking as well as possible virus-specific disease process can be speculated.…”

“…The inconsistency of the effect of viral infection on FE NO level is not fully explained but the differences in method, sample size, gender, atopy, allergy, asthma of study subjects, maternal smoking as well as possible virus-specific disease process can be speculated. The infants with future wheezing episodes in 2 years [132], and young children <4 years of age with clinical index for predicting asthma at school age [133] already present elevated level of FE NO . FE NO in young children with history of recurrent wheezing is also higher than healthy control and children with other pulmonary diseases [134], and atopic wheezers show higher FE NO than nonatopic wheezers [134].…”

Highlights from This Issue

“…In this small study, the FeNO values between cases and controls were quite similar, although there were two outliers in the bronchiolitis with wheezing group who appeared to have substantially higher FeNO values than the others. 9 This study is important in that it documents the lack of value of FeNO in assessment of the acute phase of bronchiolitis. The findings are also provocative-does FeNO measurement of infants presenting with RSV bronchiolitis identify a subgroup at increased risk for later wheezing?…”