Obstructive defect on spirometry in a 9-year-old child

Note the reduced FEV₁/FVC and FEV₁ (red circles) and the scooped curve shape of the dotted green expiratory flow loop (arrow, above X-axis), consistent with an obstructive defect. The airflow obstruction is reversible.

After treatment with a bronchodilator, there is significant improvement (>10%) in FEV₁, and the FEV₁/FVC ratio also increases (orange boxes). The expiratory flow volume loop (above X-axis) shown in solid blue is now nearly normal.