Peak expiratory flow
(重定向自Peak flow)

![Normal values, shown on EU scale.[2]](/Images/godic/202502/01/Normal_values_for_peak_expiratory_flow_-_EU_scale2423.png")

The peak expiratory flow (PEF), also called peak expiratory flow rate (PEFR) is a person's maximum speed of expiration, as measured with a peak flow meter, a small, hand-held device used to monitor a person's ability to breathe out air. It measures the airflow through the bronchi and thus the degree of obstruction in the airways.