How to Measure Your Peak Expiratory Flow
Set the meter to its lowest number: Step 1
Put the pointer on the gauge of the peak flow meter to 0 or the lowest number on the meter. In the photo, this is about 50.
Attach the mouthpiece: Step 2
Attach the mouthpiece to the peak flow meter. Some meters don't have a separate mouthpiece.
Take a deep breath: Step 3
While standing, take a deep breath.
Put the mouthpiece in your mouth: Step 4
Put the peak flow meter mouthpiece in your mouth, and close your lips tightly around the outside of the mouthpiece. Don't put your tongue inside the mouthpiece.
Breath out hard: Step 5
Breathe out as hard and as fast as you can for 1 or 2 seconds. A hard and fast breath usually produces a "huff" sound.
Check your number: Step 6
Check the number on the gauge, and write it down. This is your peak expiratory flow (PEF). In the photo, the PEF is about 180.
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