Small Airway Dysfunction Measured by Impulse Oscillometry and Fractional Exhaled Nitric Oxide Is Associated With Asthma Control in Children

Abstract

BackgroundImpulse oscillometry (IOS) and fractional exhaled nitric oxide (FeNO) are sensitive and non-invasive methods to measure airway resistance and inflammation, although there are limited population-based studies using IOS and FeNO to predict asthma control.ObjectiveThis study aimed to investigate the utility of IOS and FeNO for assessing childhood asthma control in terms of small airway dysfunction and airway inflammation.MethodsThis prospective observational cohort study enrolled 5,018 school children (aged 6–12 years), including 560 asthmatic children and 140 normal participants. FeNO, spirometry, IOS, bronchial dilation test, total IgE, and childhood asthma control test (C-ACT) were measured. FeNO, IOS, spirometry, and C-ACT results were correlated with childhood asthma with and without control.ResultsUncontrolled asthmatic children had abnormal FeNO, IOS, and spirometric values compared with control subjects (P < 0.05). IOS parameters with R5, R5-R20, X5, Ax, △R5, and FeNO can predict lower C-ACT scales by the areas under receiver operating characteristic curves (AUCs) (0.616, 0.625, 0.609, 0.622, 0.625, and 0.714). A combination of FeNO (>20 ppb) with IOS measure significantly increased the specificity for predicting uncontrolled asthma patients compared with FeNO alone (P < 0.01). A multiple regression model showed that small airway parameter (R5-R20) was the strongest risk factor [OR (95% CI): 87.26 (7.67–993.31)] for uncontrolled asthma patients. Poor control with lower C-ACT scales correlated with high FeNO (r = −0.394), R5 (r = −0.106), and R5-R20 (r = −0.129) in asthmatic children (P < 0.05).ConclusionA combined use of FeNO and IOS measurements strongly predicts childhood asthma with or without control.

Asthma control associated with anxiety and depression in asthmatic children following post‐acute COVID‐19

“…34 Monitoring FENO levels can offer information on airway inflammation levels and help in treatment decisions. 35 We have shown a correlation between FENO levels and asthma control. 34,36 Elevated FENO levels observed during hospitalization were associated with pulmonary parenchymal involvement and cytokine storm in patients with COVID-19.…”

“…Using FENO assessment provides a convenient and non-invasive approach that could aid in monitoring parenchymal infiltration in these patients. 37 35,38 Due to strict lockdown policies and a lack of approval from public health authorities, it was not feasible to include post-COVID-19 asthmatic children with spirometry from the national survey. The clinical diagnosis of asthma with recurrent wheezing during the previous year was established according to the GINA criteria by a pediatric respiratory specialist.…”

Effect of Obesity on Lung Function in the Pediatric and Adult Populations with Asthma: A Review

“…This is useful in patients with alterations in thoracoabdominal compliance, obstructive pulmonary symptoms with normal spirometry, or in obese patients for whom it is not clear whether they have an obstructive or restrictive pulmonary pattern [ 69 , 70 ]. Previous studies have shown a strong correlation between an increase in resistance at 5 Hertz (Hz) minus 20 Hz (R5 − R20) in patients with small airway dysfunction and uncontrolled asthma [ 71 , 72 ]. In addition, the distal obstruction pattern can be identified by the R5 Hz value, which is higher than the upper limit of normality or greater than 1.64 standard deviations (SD) of the predicted value with normal R20 and AX values.…”

Impulse oscillometry for the evaluation and management of pediatric asthma

“…Observational studies have shown that the measurement of SAD through IOS parameters and FeNO can increase the accuracy of identifying uncontrolled asthma in pediatric patients [54,55]. In a study of 79 preschool children (ages 3-6 years), those with uncontrolled asthma had greater evidence of SAD, as measured by IOS parameters X5, AX, R5-R20, and FeNO levels, compared to children with controlled asthma [54]. The combination of IOS and FeNO improved the accuracy of the test in distinguishing controlled versus uncontrolled patients.…”

“…The combination of IOS and FeNO improved the accuracy of the test in distinguishing controlled versus uncontrolled patients. The area under the curves in the receiver operating characteristic (ROC) analysis was 0.786 for FeNO alone, 0.751 for the IOS X5 parameter alone, and 0.866 for X5 combined with FeNO (cut-off value: 27 ppb) [54]. Similarly, in a large cohort of 560 school-age children (ages 6-12 years), the IOS parameter R5-R20 was the strongest predictor of uncontrolled asthma among lung function tests, including spirometry and FeNO [55].…”