What is peak expiratory flow rate (PEFR)?

Peak expiratory flow rate (PEFR) measures the highest speed at which a person can exhale air from the lungs after taking a deep breath. It is commonly used to assess airflow limitation in conditions like asthma and chronic obstructive pulmonary disease (COPD). By determining the maximum flow rate achieved during exhalation, PEFR provides important information about the patency of the airways and helps in monitoring respiratory health.

In clinical practice, a peak flow meter is typically used to determine the PEFR, assisting both patients and healthcare providers in managing respiratory conditions effectively. This measurement is crucial because it can indicate changes in airway resistance and can help guide medication adjustments and treatment plans.

Understanding the other provided options highlights why they do not accurately define PEFR. The lowest point of airflow during breathing does not reflect the peak flow; rather, it describes a state of reduced airflow, often observed in respiratory distress. The total volume of air expelled from the lungs in one second refers to forced expiratory volume (FEV1), which assesses volume rather than flow speed. The average speed of airflow throughout normal breathing does not capture the maximum effort a person can exert during forced expiration, which is what PEFR represents. Therefore, defining PEFR specifically as the highest speed