Atopic Dictionary
PEF is an acronym for "peak expiratory flow". It refers to the maximum flow of air during exhalation (after a prior deep inhalation). It is measured in liters per minute. It is usually measured with a handheld meter that looks like a mouthpiece, through which the person forcefully exhales (after a prior deep inhalation). PEF is commonly used to monitor asthma treatment.
