Using a Peak Flow Meter

Using a Peak Flow Meter

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Using a Peak Flow Meter

Hand holding peak flow meter with marker set at bottom.

Woman with peak flow meter in mouth, blowing into it.

Hand holding peak flow meter with marker at number to look at.

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 often as instructed to do so by your health care provider. For example, it may be once a day or only when you think your symptoms are getting worse.

How to Use a Peak Flow Meter

Step 1:

  • Move the marker to 0, or to the lowest number on the scale.

  • Stand. (If you can’t stand, be sure to sit up straight.) Make sure you’re in the same position each time you test.

Step 2:

  • Take as deep a breath as you can.

  • Put the mouthpiece in your mouth, between your teeth. Close your lips tightly around it. Be sure your tongue does not block the opening.

  • Blow into the mouthpiece once, as hard and as fast as you can.

Step 3:

  • 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 and take the record with you when you see your health care provider.

Determining Your Personal Best

Your personal best is your highest peak flow number during 2 weeks when you do not have symptoms. Your other peak flow results are compared to your personal best. This helps you and your provider know how you are doing on days when you have symptoms. To find your personal best:

  • Step 1: Check your peak flow twice a day for 2 weeks. Do this when you are not having any asthma symptoms.

  • Step 2: Write down your peak flow readings and your personal best.