Exhaled nitric oxide during infancy as a risk factor for asthma and airway hyperreactivity

Abstract

Childhood asthma is often characterised by elevated exhaled nitric oxide (eNO), decreased lung function, increased airway reactivity and atopy; however, our understanding of when these phenotypic airway characteristics develop remains unclear. This study evaluated whether eNO, lung function, airway reactivity and immune characteristics during infancy are risk factors of asthma at age 5 years. Infants with eczema, enrolled prior to wheezy illness (n=116), had eNO, spirometry, airway reactivity and allergen sensitisation assessed at entry to the study and repeated at age 5 years (n=90). Increasing eNO at entry was associated with an increased risk of asthma (p=0.037) and increasing airway reactivity (p=0.015) at age 5 years. Children with asthma at 5 years of age had a greater increase in eNO between infancy and age 5 years compared with those without asthma (p=0.002). Egg sensitisation at entry was also associated with an increased risk of asthma (p=0.020), increasing eNO (p=0.002) and lower forced expiratory flows (p=0.029) as a 5 year-old. Our findings suggest that, among infants at high risk for developing asthma, eNO early in life may provide important insights into the subsequent risk of asthma and its airway characteristics.

The Clinical Utility of Fractional Exhaled Nitric Oxide (FeNO) in Asthma Management

“…166 Both single measurements and changes of FeNO (10 ppb, 15 ppb, or an increase of > 60% over baseline) had positive predictive values that ranged from 80 to 90 percent for predicting and diagnosing loss of asthma control after ICS withdrawal. 167 In adult patients with moderate or severe asthma but no clinical symptoms of asthma for at least 6 months in whom ICS dose was reduced by half, FeNO was a statistically independent predictor of success. 168 However, the response of FeNO in adults with moderate persistent asthma undergoing withdrawal of ICS was heterogeneous.…”

NO kidding: exhaled nitric oxide fraction in preschool children

“…One of the strengths of the study by CHANG et al [6] is that it supports the concept that eosinophilic inflammation develops and increases in early childhood, and is a progressive phenomenon. Data from biopsy studies suggest that eosinophilic inflammation, which is a hallmark of asthma in school children, develops between 1 and 3 years of age [15,16].…”

“…By carrying out serial FeNO measurements between 1 and 5 years of age, or even from birth to school age, better insight into when eosinophilic inflammation starts could be obtained. CHANG et al [6] suggest a gradual increase of FeNO during the study period, although this is somewhat speculative as only two measurements were available. It is well known that FeNO increases with age during childhood [17], and it is remarkable that FeNO does not seem to show this increase in the children who did not have asthma at 5 years of age.…”

“…In this issue of the European Respiratory Journal, CHANG et al [6] showed that in infants and toddlers at high risk of developing asthma, prior to the first episode of wheezing, elevated FeNO was associated with a higher risk of asthma and increased airway reactivity at 5 years of age. This study differs from earlier studies on the predictive value of FeNO for asthma later in life as it included children from general paediatric practices before the first episode of wheezing and measured FeNO with an online single breath technique.…”

“…In the current study by CHANG et al [6], FeNO was measured online with a constant expiratory flow during sedation, possibly resulting in minimal dilution with gas from the anatomical dead space and enhancing the sensitivity of the measurement. Although this technique makes comparison with standardised single breath online measurements at 5 years of age possible, only a few, specialised centres will have this technique available.…”