Fractional Exhaled Nitric Oxide (FeNo) in Different Asthma Phenotypes

Abstract

Fractioned exhaled nitric oxide (FeNO) is a noninvasive marker of inflammation in asthmatic patients. FeNO can be used to monitor airway inflammation, but individual responses make tailored interventions based on FeNO difficult. The correlation between the asthma control test (ACT), FEV1, and FeNO was evaluated in this study to ascertain the correct usage of FeNO with different asthma phenotypes regarding their control, allergy, comorbidity, obesity, age, smoking status, and severity. ACT, pulmonary function, and FeNO in 416 asthmatic patients on combined therapy were retrospective evaluated. Correlations between these parameters and the FeNO levels in different asthma phenotypes were calculated. In the study population, FeNO was 31.8 ± 28.5 parts per billion (ppb), FEV1 was 83.4 ± 19% and ACT was 19 ± 5.2. ACT scores were negatively correlated with FeNO (r = −0.31; p = 0.002). FeNO was different in patients with positive and negative skin-prick test (p < 0.05), with and without allergic rhinitis (p < 0.01), and with and without allergic conjunctivitis (p < 0.01). Significantly higher FeNO levels were found with logistic regression analysis only in patients with a history of emergency room visits (ERVs) (p = 0.024). The rate of the ERV of the patients with an ACT score more than or equal to 20 and with a FeNO value of more than 35 ppb was 22.9%, but with a FeNO value of less than 35 ppb was 6.5% (p = 0.004). Allergy and allergic comorbidities may lead to an increase in FeNO levels. Patients with a history of ERV have markedly higher FeNO levels, although they have an ACT score more than or equal to 20.

Determinants of fractional exhaled nitric oxide in healthy men and women from the European Community Respiratory Health Survey III

“…Taylor et al studied 895 healthy adults at age 32 years and found that men had approximately 25% higher F E NO levels than women (15.5 vs 11.6 ppb). A similar size of the sex difference has also been reported in asthmatic subjectsfor example, Al‐shamkhi et al reported that in 557 subjects with asthma from the Swedish GA2LEN study, men had 32% higher F E NO levels than women (24.0 vs 16.4 ppb). However, not all studies have been able to detect sex differences in F E NO .…”

Acute Effects of Air Pollution and Noise from Road Traffic in a Panel of Young Healthy Subjects

“…Exhaled NO originates from different sources [44][45][46]. It is secreted by epithelial cells, inducing relaxation of the smooth muscle cells in the bronchial walls.…”

A simple prediction tool for inhaled corticosteroid response in asthmatic children

“…In a prior study, Cowan DC et al used the data from 46 asthmatic patients and found that the odds ratio of having a steroid response versus having no steroid response for high eNO value (>35 ppm) was 6.0. [ 19 ] In addition, we assumed the prevalence of ICS non-responders was 40% (22–60% from literature review) and that low eNO prevalence was 0.63 [ 20 ]. Thus, for one variable of odds ratio that equals to 6.0, a sample size of 51 total patients would be needed to provide 80% power with a 5% two-sided type I error.…”