Alveolar nitric oxide and its role in pediatric asthma control assessment

Abstract

BackgroundNitric oxide can be measured at multiple flow rates to determine proximal (maximum airway nitric oxide flux; JawNO) and distal inflammation (alveolar nitric oxide concentration; CANO). The main aim was to study the association among symptoms, lung function, proximal (maximum airway nitric oxide flux) and distal (alveolar nitric oxide concentration) airway inflammation in asthmatic children treated and not treated with inhaled glucocorticoids.MethodsA cross-sectional study with prospective data collection was carried out in a consecutive sample of girls and boys aged between 6 and 16 years with a medical diagnosis of asthma. Maximum airway nitric oxide flux and alveolar nitric oxide concentration were calculated according to the two-compartment model. In asthmatic patients, the asthma control questionnaire (CAN) was completed and forced spirometry was performed. In controls, differences between the sexes in alveolar nitric oxide concentration and maximum airway nitric oxide flux and their correlation with height were studied. The correlation among the fraction of exhaled NO at 50 ml/s (FENO50), CANO, JawNO, forced expiratory volume in 1 second (FEV1) and the CAN questionnaire was measured and the degree of agreement regarding asthma control assessment was studied using Cohen’s kappa.ResultsWe studied 162 children; 49 healthy (group 1), 23 asthmatic participants without treatment (group 2) and 80 asthmatic patients treated with inhaled corticosteroids (group 3). CANO (ppb) was 2.2 (0.1-4.5), 3 (0.2-9.2) and 2.45 (0.1-24), respectively. JawNO (pl/s) was 516 (98.3-1470), 2356.67 (120–6110) and 1426 (156–11805), respectively. There was a strong association (r = 0.97) between FENO50 and JawNO and the degree of agreement was very good in group 2 and was good in group 3. There was no agreement or only slight agreement between the measures used to monitor asthma control (FEV1, CAN questionnaire, CANO and JawNO).ConclusionsThe results for CANO and JawNO in controls were similar to those found in other reports. There was no agreement or only slight agreement among the three measure instruments analyzed to assess asthma control. In our sample, no additional information was provided by CANO and JawNO.

Exhaled NO: Determinants and Clinical Application in Children With Allergic Airway Disease

“…C A NO is typically <5 ppb and has been found to be elevated in severe asthma and potentially reduced by oral prednisone, since it reflects distal airway inflammation. 66 69 Increased C A NO had significantly worse asthma control and morbidity in children with asthma.…”

An Overview of Fractional Exhaled Nitric Oxide and Children with Asthma

“…FeNO levels have been described to be higher in allergic or atopic asthma compared to nonallergic asthma [45], but are also elevated in children who have allergic sensitization as demonstrated by positive skin-prick testing or aeroallergen-specific IgE [32,35,43]. FeNO levels have been shown to be higher in children with allergic sensitization or atopy and no asthma compared to nonallergic asthma [32,35,45], and have been found to be higher in children both with treated and untreated asthma than in healthy nonatopic children [54]. …”

“…This technique can be successfully performed by children, although younger children may have trouble completing the test at all flows [35,54]. C alv may not be affected by ICS as much as FeNO, and has been shown to be elevated both in adults and children with asthma treated with ICS [35,77], although a newer study by Sardon et al showed that there was no difference [54].…”

“…This technique can be successfully performed by children, although younger children may have trouble completing the test at all flows [35,54]. C alv may not be affected by ICS as much as FeNO, and has been shown to be elevated both in adults and children with asthma treated with ICS [35,77], although a newer study by Sardon et al showed that there was no difference [54]. Paraskakis et al showed in their cohort of children, a number of whom had severe asthma, that C alv was elevated in children with asthma, but not in nonasthmatic atopic children [35], suggesting that alveolar NO may be less influenced by atopy compared to conventional FeNO.…”

Exhaled NO: Determinants and Clinical Application in Children With Allergic Airway Disease

“…CANO is typically <5 ppb and has been found to be elevated in severe asthma and potentially reduced by oral prednisone, since it reflects distal airway inflammation. 66,69 Increased CANO had significantly worse asthma control and morbidity in children with asthma.…”