High fractional exhaled nitric oxide levels in asthma patients: Does size matter?

Abstract

Background: Fractional exhaled nitric oxide (FeNO) is a biomarker for eosinophilic inflammation used for diagnosis and monitoring of asthma. High FeNO indicates significant airway eosinophilia and steroid-responsive airway inflammation. Some children with asthma have extremely high FeNO levels, but whether these levels represent a different asthma phenotype compared with those with mildly elevated FeNO is unclear. The objective of this study is to investigate whether the extent of high FeNO levels correlates with clinical phenotype, asthma control, comorbidity, and pulmonary function test (PFT) findings in children with asthma.Methods: Anthropometric data, daytime and nighttime symptoms, controller treatment, comorbidity, and PFT findings were retrieved from the Pediatric Pulmonology Unit database (2014-2020) and correlated with FeNO levels in pediatric asthma patients with high FeNO levels.Results: Two-hundred children and adolescents with high FeNO levels (range 36-227 ppb) were included. Within this range, higher FeNO levels positively correlated with increased daytime and nighttime symptoms (p = .013 and p = .01, respectively) and poorly controlled asthma (p = .034). A FeNO level of ≥80 ppb was the cutoff for significantly more severe daytime and nighttime symptoms and very poorly controlled asthma compared with levels <80 ppb (p = .004, p = .005, and p = .036, respectively). No correlation was found between FeNO and controller treatment, comorbidity, and PFT performance. Conclusion:In pediatric asthma patients, high FeNO levels correlate with increased symptom severity and poor asthma control. A FeNO level of ≥80 ppb may serve as an objective indicator for severe asthma.

Effects of the salbutamol bronchodilator response on measurements of fractional exhaled nitric oxide in children with asthma: a prospective, observational study

“…However, there was a marked difference in the median baseline FeNO values between these groups (P=0.048), suggesting that FeNO values could be used to assess the level of asthma control. Diamant et al found that high FeNO levels were association with poor asthma control in asthmatic children ( 25 ). Kavitha et al recruited 151 asthmatic patients over 18 months and found that FeNO levels were a useful monitoring tool to assess asthma control ( 26 ).…”

Prediction of Asthma Exacerbations in Children

“…Moreover, the investigators showed that FeNO was the only significant and independent predictor of exacerbations compared to spirometric indices, quality of life scores, and medication usage [88]. On the other hand, similar studies in asthmatic children found that a single FeNO measurement is not useful in assessing the risk of an upcoming exacerbation [89,90]. In the Reducing Asthma Attacks in Children using Exhaled Nitric Oxide trial, a combined approach based on symptom-guided asthma treatment and FeNO levels did not reduce the asthma attacks [91,92].…”

Pediatric pulmonology 2021 year in review: Asthma

“…A study in Israel examined fractional exhaled nitric oxide (FeNO), a commonly use biomarker and tool for asthma diagnosis and disease monitoring. 20 FeNO value of >35 ppb is defined as "high" in children. However, FeNO levels may be significantly higher than the 35 ppb cutoff.…”

“…Once a patient is diagnosed with asthma, close monitoring is essential for maintaining adequate control. A study in Israel examined fractional exhaled nitric oxide (FeNO), a commonly use biomarker and tool for asthma diagnosis and disease monitoring 20 . FeNO value of >35 ppb is defined as “high” in children.…”