A Peak Flow Meter (PFM) is a device used to measure the fastest speed in which you can blow air out of your lungs. During an asthma flare-up, the large airways in your lungs slowly begin to narrow. This will slow the speed of air leaving your lungs and can be measured by a PFM. This measurement is very important to you and your doctor in judging how well or how poorly your asthma is being controlled.
This handout is courtesy of CHKD.