Objective measures of lung function are important in the diagnosis and management of asthma, yet most preschoolers cannot perform spirometry.
Impulse oscillometry, which is performed during tidal breathing, is a method by which lung function measures can be obtained in preschool children.
Impulse oscillometry can be useful in determining baseline lung function, demonstrating response to bronchodilator or bronchoprovocation, and predicting asthma exacerbations and loss of disease control.
Fractional exhaled nitric oxide (FeNO) levels reflect eosinophilic inflammation and predict responsiveness to corticosteroids.
Although FeNO has been used to discriminate among wheezing phenotypes, the role of FeNO in preschool wheezing remains unclear.