In a patient diagnosed with chronic bronchitis, which pulmonary function test finding is anticipated?

In chronic bronchitis, one of the main pathophysiological changes is airway inflammation and obstruction, primarily due to prolonged exposure to irritants such as smoking or environmental pollutants. This leads to a characteristic decrease in the forced expiratory volume in one second (FEV1).

FEV1 is a crucial measure in pulmonary function tests that quantifies the volume of air a patient can forcibly exhale in the first second of a forced breath. In chronic bronchitis, the increased mucus production and airway narrowing significantly impair airflow, particularly during expiration. As a result, patients show a reduced FEV1 value, which is a hallmark of the disease and reflects the obstructive nature of the condition.

In contrast, other choices, such as increased total lung capacity and decreased lung compliance, are not specific indicators of chronic bronchitis. While total lung capacity may be increased due to air trapping in some cases, it is the decreased FEV1 that directly corresponds to the obstructive pathology observed in chronic bronchitis. Lastly, increased diffusing capacity is typically not associated with chronic bronchitis, as that would suggest better gas exchange capabilities than what is present in obstructive lung diseases. Therefore, the decrease in FEV1 aligns closely with the typical presentation and physiology