American Board of Internal Medicine (ABIM) Certification Practice Exam

In asthma diagnosis via spirometry, what is the significant bronchodilator response criteria?

1. 100 mL and 10% increase in FEV1

2. 200 mL and 12% increase in FEV1

3. 300 mL and 15% increase in FEV1

4. 400 mL and 20% increase in FEV1

The correct answer is: 200 mL and 12% increase in FEV1

In the context of asthma diagnosis using spirometry, a significant bronchodilator response is defined by specific criteria that indicate a considerable improvement in lung function following the administration of a bronchodilator. The established criteria for a significant bronchodilator response typically include an increase of at least 200 mL in forced expiratory volume in one second (FEV1) and a 12% increase relative to the baseline FEV1. Choosing a 200 mL increase in FEV1 alongside a 12% rise is crucial because it aligns with clinical standards set by guidelines and expert consensus. This dual criterion helps to ensure that the observed improvements are not only clinically relevant but also statistically significant, ruling out minor fluctuations in lung function that might occur due to factors unrelated to bronchodilator efficacy. In contrast, thresholds that either set the volume gain too low, like 100 mL, or those that demand a higher volume increase or percentage than established norms, such as 300 mL or 400 mL combined with higher percentage increases, would not be appropriate for confirming significant bronchodilator reversibility in diagnosing asthma. By using the 200 mL and 12% increase criteria, healthcare professionals can better differentiate asthma from other respiratory conditions