Peak flowmeters monitor a  human’s ability to breathe out air thus measuring the flow of air through the bronchi and determining the degree of obstruction in the air passages.

The maximum speed of expiration, or peak expiratory flow rate (PEFR or PEF) are higher when subjects/patients are well, and lower when the air passages are constricted. From monitoring the  changes in noted measured values,  both thepatients and doctors can determine lung functionality, how severe are the asthma symptoms and thus more able to discuss possible treatment options. Consult your local physician if you are interested in more information.