If the FEV1/FVC ratio is less than 70%, what condition is likely present?

The FEV1/FVC ratio is a key indicator used in pulmonary function tests to assess lung function. FEV1 (Forced Expiratory Volume in one second) measures how much air a person can forcibly exhale in one second, while FVC (Forced Vital Capacity) measures the total volume of air that can be exhaled after taking a deep breath. A ratio of less than 70% typically indicates obstructive lung disease.

In obstructive lung diseases, such as asthma, chronic obstructive pulmonary disease (COPD), or emphysema, airflow is impeded during exhalation. This results in a lower FEV1 relative to the FVC, causing the ratio to drop below the normal threshold of 70%. The presence of this ratio suggests that the patient struggles to move air out of the lungs effectively, which is characteristic of disorders that obstruct the airways.

Restrictive lung diseases, on the other hand, typically cause a decrease in both FEV1 and FVC, but the FEV1/FVC ratio generally remains normal or even increased, as the reduction in lung volume affects both measurements similarly. Conditions that fall under restrictive lung disease include pulmonary fibrosis or pleural effusions.

Nonspecific lung disease and