Using a Peak Flow Meter

A peak flow meter measures how fast you breathe out or push air out of your lungs. This tells you how well you are controlling your asthma. Check your peak flow as needed and as often as instructed by your doctor. For instance, it may be once a day. Or it may be only when you think your symptoms are getting worse.

• Move the marker to 0. Or move it to the lowest number on the scale.
• Stand upright. Don't slouch. If you can't stand, sit up straight. Make sure you are in the same position each time you test.

• If you have gum or food in your mouth, remove it.
• Slowly take in a deep breath.
• While holding your breath, put the mouthpiece in your mouth, between your teeth. Close your lips tightly around it. Check that your tongue does not block the opening.
• Blow into the mouthpiece once, as hard and as fast as you can.

• Take the meter out of your mouth.
• Look at the marker. It will have moved along the numbered scale. Write this number down.
• Move the marker back to 0, or to the lowest number on the scale.
• Repeat the test 2 more times.
• Write down your readings each time. Take them with you when you see your doctor.

Your personal best is your highest peak flow number during 2 weeks when you don't have symptoms. The American Lung Association advises repeating the steps above 3 times, preferably at the same time each day. Record the highest number. Your other peak flow results are compared with your personal best. This helps you and your doctor know how you are doing on days when you have symptoms. This includes when you are using an Asthma Action Plan as directed by your doctor. To find your personal best:

• Step 1. Check your peak flow 2 to 3 times a day for 2 weeks at the same time each day, if possible. Do this when you are not having any asthma symptoms.
• Step 2. Write down your peak flow readings and your personal best.