What pulmonary function test finding may suggest vocal cord dysfunction in a patient with exercise-induced asthma?

The finding that suggests vocal cord dysfunction in a patient experiencing exercise-induced asthma is the flattening of the inspiratory portion of the flow volume loop. Vocal cord dysfunction can mimic asthma symptoms and is characterized by paradoxical movement of the vocal cords, which leads to abnormal airflow patterns—especially during inhalation.

When the inspiratory phase of the flow volume loop is flattened, it indicates a restriction in airflow primarily during inhalation, which is a hallmark of vocal cord dysfunction. This is distinctly different from typical asthma, where you may see a reduction in both the inspiratory and expiratory flows, but particularly marked changes in expiratory flow, especially in obstructive patterns.

The other choices do not correlate with the expected findings for vocal cord dysfunction. The decreased FEV1 with a normal FVC would suggest a restrictive pattern more consistent with pulmonary conditions like interstitial lung disease rather than vocal cord issues. Increased FEV1 with an expiratory wheeze aligns more with asthma or bronchospasm, indicating an obstructive pattern rather than vocal cord dysfunction. Lastly, a normal inspiratory phase does not suggest vocal cord dysfunction since the hallmark of this condition is the presence of abnormal inspiratory flow dynamics.