American Board of Family Medicine (ABFM) Practice Exam

What condition should be considered in a patient with chronic shortness of breath and a low DLCO?

1. Chronic pulmonary thromboembolism

2. Emphysema

3. Interstitial lung disease

4. Asthma

The correct answer is: Chronic pulmonary thromboembolism

In a patient experiencing chronic shortness of breath accompanied by a low diffusing capacity for carbon monoxide (DLCO), the condition that should be considered is chronic pulmonary thromboembolism. A low DLCO typically indicates issues with gas exchange, which can occur due to various lung diseases. Chronic pulmonary thromboembolism can lead to increased resistance in the pulmonary vasculature, resulting in pulmonary hypertension and impaired gas exchange. Over time, this condition can significantly impact the patient’s ability to breathe and participate in physical activities, correlating with the chronic shortness of breath. While other conditions, such as emphysema and interstitial lung disease, can also present with a low DLCO, they generally present with distinct features in terms of lung function and symptomatology. Emphysema is characterized by airflow limitation and often presents with features such as increased total lung capacity, while interstitial lung disease would be expected to show restrictive patterns and varying degrees of DLCO reduction depending on the type and severity of the disease. Asthma, on the other hand, usually does not result in a decreased DLCO unless there are significant complications. It typically presents with a normal lung volume and a more reactive airways profile. Thus, considering the combination of