What happens to the FEV1/FVC ratio after bronchodilator treatment in asthma?

Following bronchodilator treatment in asthma, the FEV1/FVC (Forced Expiratory Volume in one second to Forced Vital Capacity) ratio typically improves. This improvement is primarily due to bronchodilation, which helps to open up narrowed airways, allowing for better airflow during forced expiration.

In patients with asthma, the airflow limitation is often reversible, meaning that after the administration of a bronchodilator, practitioners usually observe an increase in FEV1 (the volume of air that can be forcibly exhaled in the first second) more significantly than any changes in FVC (the total volume of air that can be forcibly exhaled). As a result, the numerator of the ratio (FEV1) increases, leading to a comparatively higher FEV1/FVC ratio, which reflects an improvement in airway function.

In summary, bronchodilator treatment alleviates the bronchoconstriction associated with asthma, thereby enhancing airflow, which positively affects the FEV1/FVC ratio.