In a case of emaciated male patient with a smoking history, what respiratory function test result supports emphysema?

In the context of emphysema, a decreased FEV1/FVC ratio is significant because it indicates an obstructive pattern of lung disease. In patients with emphysema, the destruction of the alveolar walls leads to decreased elasticity and airflow limitation during expiration. As a result, the forced expiratory volume in one second (FEV1) is decreased more than the forced vital capacity (FVC), leading to a reduced FEV1/FVC ratio.

This ratio is critical in differentiating between obstructive and restrictive lung diseases; a ratio less than 70% typically indicates an obstructive disease like emphysema. In this scenario, the patient's smoking history also strengthens the likelihood of emphysema, as smoking is a major risk factor for the development of this condition.

While other results may present in patients with emphysema, such as high total lung capacity due to hyperinflation or a normal peak expiratory flow in certain cases, the distinct decrease in the FEV1/FVC ratio serves as a key diagnostic feature of emphysema.