Expired nitric oxide and airway reactivity in infants at risk for asthma

Abstract

Background Family histories of atopy, as well as histories of atopic dermatitis and food allergy, are important risk factors for an infant to have asthma. Although atopic sensitization appears to contribute to the development of asthma, it is unclear when the airways become involved with the atopic process and whether airway function relates to the atopic characteristics of the infant. Objective We sought to evaluate whether atopic infants without prior episodes of wheezing have increased expired nitric oxide (eNO) levels and heightened airway reactivity. Methods Infants with eczema were recruited, and atopic status was defined by specific IgE levels to foods or aeroallergens and total IgE levels. eNO, forced expiratory flow at 75% exhaled volume (FEF75), and airway reactivity to inhaled methacholine were measured in sedated infants. Airway reactivity was quantified by using the provocative concentration to decrease FEF75 by 30%. Results Median age for the 114 infants evaluated was 10.7 months (range, 2.6–19.1 months). Infants sensitized to egg or milk compared with infants sensitized to neither egg nor milk had lower flows (FEF75: 336 vs 285 mL/s, P < .003) and lower lnPC30 (mg/mL) provocative concentrations to decrease FEF75 by 30% (−0.6 vs −1.2, P < .02) but no difference in eNO levels. Infants with total serum IgE levels of greater than 20 IU/mL had higher eNO levels compared with infants with IgE levels of 20 IU/mL or less (14.6 vs 11.2 ppb, P < .023) but no difference in forced flows or airway reactivity. Conclusions Our findings suggest that atopic characteristics of the infant might be important determinants of the airway physiology of forced expiratory flows, airway reactivity, and eNO.

Factors associated with elevated exhaled nitric oxide fraction in infants with recurrent respiratory symptoms

“…As well, the maternal history of asthma or atopy has been reported to modify FeNO levels in certain selected cohorts of infants [9,17], that is consistent with our finding on the association between elevated FeNO and a maternal history of asthma. It has been speculated that the milk of asthmatic and/or atopic mothers may differ from the milk of nonasthmatic and/or nonatopic mothers with regard to immunologically active substances and affect the outcome [30].…”

“…As regards online FeNO measurements, there are reports with no correlation between airway responsiveness and FeNO values [23,24], as well as reports on the association between FeNO and increased airway responsiveness to methacholine [3], histamine [2], and acetylcholine chloride [4]. Studies on infants are scarce: in a study on the relationship of FeNO and airway responsiveness in infants with eczema, there was a correlation between FeNO and increased airway responsiveness to methacholine [9].…”

“…However, the role of FeNO in respiratory disorders of early childhood has not been established: wheezing illnesses in infancy are usually not associated with eosinophilic bronchial inflammation [6,7], and although increased airway responsiveness may play a role in recurrent lower respiratory tract symptoms of early childhood [8], studies on the relationship of FeNO and increased airway responsiveness in infants are scarce [9]. In addition, there are several characteristics influencing FeNO values: i.e.…”

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

“…22 Tepper compared the FENO values in children with a history of allergy to eggs or milk in the first 2 years of life and no episodes of previous wheezing with those not sensitized, and there were no significant differences. 23 These data show that a background of atopia and bronchial hyperactivity are related to FENO values. In our study, we cannot demonstrate that patients with a background of atopia present high values of FENO in the acute phase of the first episode.…”

Exhaled Nitric Oxide Predicts Persistence Of Wheezing, Exacerbations, And Decline In Lung Function In Wheezy Infants And Toddlers

“…[19][20][21] In atopic infants at risk for asthma, FE NO was associated with airway reactivity. [22] Furthermore, among adults with chronic respiratory symptoms FE NO has been shown to be a superior predictor of steroid responsiveness than spirometry, BDR, or airway reactivity to methacholine or adenosine. [23] ATS FE NO Clinical Practice Guidelines [24] recommend use of FE NO to diagnose eosinophilic airway inflammation, determine likelihood of steroid responsiveness, and support the diagnosis of asthma when objective evidence is lacking.…”