Which test best demonstrates reversible airway obstruction in suspected asthma?

Which test best demonstrates reversible airway obstruction in suspected asthma?

• A. Chest X-ray showing pneumonia
• B. Spirometry showing reversible airway obstruction
• C. CT scan showing calcifications
• D. MRI

Answer: (B)

Reversible airway obstruction is best demonstrated by a functional lung test that shows improvement after a bronchodilator. Spirometry provides objective measures of airflow, revealing an obstructive pattern with reduced FEV1 and a low FEV1/FVC ratio. When a fast-acting bronchodilator is given and spirometry is repeated, a meaningful improvement in FEV1 confirms reversibility. The standard criterion is an increase in FEV1 of about 12% plus at least 200 mL from baseline. Imaging studies like chest X-ray for pneumonia, CT for calcifications, or MRI do not assess how the airways respond to bronchodilators, so they don’t demonstrate reversibility of obstruction.

Reversible airway obstruction is best demonstrated by a functional lung test that shows improvement after a bronchodilator. Spirometry provides objective measures of airflow, revealing an obstructive pattern with reduced FEV1 and a low FEV1/FVC ratio. When a fast-acting bronchodilator is given and spirometry is repeated, a meaningful improvement in FEV1 confirms reversibility. The standard criterion is an increase in FEV1 of about 12% plus at least 200 mL from baseline. Imaging studies like chest X-ray for pneumonia, CT for calcifications, or MRI do not assess how the airways respond to bronchodilators, so they don’t demonstrate reversibility of obstruction.