Adding Oscillometry and Fractional Exhaled Nitric Oxide to Guidelines Potentially Enhances Identification of Exacerbation Risk Factors in Asthmatic Children

ABSTRACT Background A possible explanation for the continued risk of asthma exacerbations while utilizing current asthma guideline‐based management is the failure to consider small airway dysfunction (SAD) and eosinophilic airway inflammation in assuming asthma‐controlled status. Objective To construct a practical algorithm that potentially identifies additional risks of not well‐controlled (NWC) asthma and exacerbations beyond guideline criteria with oscillometry and fractional exhaled nitric oxide (FENO) determination. Methods This was a retrospective, posthoc analysis of 183 children, ages 4–18 years, with moderate‐to‐severe asthma, characterized by demographic factors, National Health Lung and Blood Institute (NHLBI) determined asthma‐controlled status, therapy step, and lung function status. Impulse oscillometry (IOS) and FENO were performed before spirometry. Abnormal lung function values were determined for spirometry, SAD, and FENO based on established thresholds. Statistical analysis included a decision tree and Venn diagram. Results For 53 patients with guideline‐based NWC, 15 (28.3%) had an FEV1 ≤ 80% predicted. An additional 30 patients (56.6%) had abnormal SAD and/or FENO with a preserved FEV1. Of 130 patients, well‐controlled (WC) by guidelines 76 (58.5%) exhibited SAD and/or abnormal FENO. Conclusions These data demonstrate that over 50% of WC patients with moderate‐to‐severe asthma, with few symptoms and preserved FEV1, had SAD and/or abnormal FENO levels, suggesting the potential of early phenotype‐specific therapy to prevent risk of future exacerbations.