What would a significant decrease in FEV1 indicate in a PFT?

A significant decrease in FEV1, or forced expiratory volume in one second, indicates obstructive airway disease. In obstructive conditions such as asthma, chronic obstructive pulmonary disease (COPD), or bronchiectasis, there is an impediment to airflow during expiration. This reduced airflow results in a lower FEV1 measurement because the airways are narrowed or obstructed, making it difficult to exhale air efficiently within the first second of the forced expiratory maneuver.

In obstructive diseases, the FEV1 value is typically compared to the forced vital capacity (FVC), and the FEV1/FVC ratio is calculated. A lower FEV1/FVC ratio, especially when FEV1 is significantly decreased, confirms the presence of obstructive pathology.

In contrast, restrictive lung disease would show a decrease in both FEV1 and FVC, but the FEV1/FVC ratio might remain normal or be increased due to a relatively larger decline in FVC compared to FEV1. Normal lung function would be indicated by expected values of FEV1 and FVC with a normal ratio. Hyperresponsive airways refer to a heightened sensitivity of the bronchial passages, often associated with asthma but does not specifically correlate with a