Abstract
Wheezing and other respiratory symptoms are frequently seen in infants and young children. It has been suggested that there exist some phenotypes of recurrent wheezing in infants and children. Pathophysiology, prognosis and long-term management may differ for each phenotype. Objective assessments of lung function and bronchial hyperresponsiveness help to distinguish between these phenotypes and to diagnose asthma. Spirometry is probably the most frequently performed lung function test. Measuring maximal forced expiratory flow-volume is important for determining the clinical utility of spirometry. Calculation of the parameters; FVC, FEV1, MMF, V'50 and V'25 is recommended to evaluate pulmonary function. Evaluating the shape of the effort-independent portion of the flow-volume curve is especially important because the shape sensitively reflects the condition of small airways. Although most infants and young children are not able to voluntarily perform the physiological maneuvers, commercial devices using impulse oscillation system (IOS) suitable for young children have become available. Using these methods, objective lung function should be evaluated for diagnosis and management of asthma in children.
