What is a Peak Flow Meter?

As part of your daily asthma self-management plan, your doctor may recommend that you use a hand-held device called a peak flow meter at home to monitor how well your lungs are working.

How to use a Peak Flow Meter

You use the peak flow meter by taking a deep breath in and then blowing the air out hard into the peak flow meter. The peak flow meter then gives you a peak flow number that tells you how fast you moved the air out.

You will need to find out your "personal best" peak flow number. You do this by recording your peak flow number every day for a few weeks until your asthma is under control. The highest number you get during that time is your personal best peak flow. Then you can compare future peak flow measurements to your personal best peak flow, and that will show if your asthma is staying under control.

Your doctor will tell you how and when to use your peak flow meter and how to use your medicines based on the results. You may be advised to use your peak flow meter each morning to keep track of how well you are breathing.

Your peak flow meter can help warn you of a possible asthma attack even before you notice symptoms. If your peak flow meter shows that your breathing is getting worse, you should follow your emergency asthma action plan.

Take your quick-relief or other medicines as your doctor directed. Then you can use the peak flow meter to see how your airways are responding to the medicine.

Ask your doctor about how you can take care of your asthma. You should know:

  • What things tend to make your asthma worse and how to avoid them
  • Early signs to watch for that mean your asthma is starting to get worse (like a drop in your peak flow number or an increase in symptoms)
  • How and when to use your peak flow meter
  • What medicines to take, how much to take, when to take them, and how to take them correctly
  • When to call or see your doctor
  • When you should get emergency treatment