What is a key indicator of effective bronchodilation?

Improvement in peak expiratory flow rate (PEFR) is a key indicator of effective bronchodilation because PEFR measures the maximum speed of expiration and reflects airway function. When bronchodilation occurs, the airways widen, allowing for easier and faster airflow out of the lungs, which is directly represented in an increase in PEFR.

Higher PEFR values indicate that the muscles around the airways are relaxed and that there is less resistance in the bronchial tubes, facilitating better airflow during expiration. Monitoring PEFR can be particularly important in conditions such as asthma or chronic obstructive pulmonary disease (COPD), where airway obstruction is prominent.

The other options, while they may reflect certain physiological changes, do not provide a direct measure of bronchodilation. For example, an increased heart rate may occur due to the use of certain bronchodilators but does not indicate the effectiveness of bronchodilation itself. Similarly, decreased blood pressure is not typically associated with bronchodilation effects and may vary independently of airway opening. A reduction in respiratory rate might suggest improved respiratory function but does not provide as clear a measure of airway patency and flow as PEFR, which specifically illustrates how effective the bronchodilation has been in terms of lung function.