How to use your peak flow meter

Measuring your peak flow (Liters per second) can tell you and your health care provider how well you blow air out of your lungs. If your airways are narrowed and blocked due to asthma, your peak flow values drop.

You can check your peak flow at home. Here are the basic steps:

Many children under age 5 cannot use a peak flow meter very well. But some are able to. Start using peak flow meters before age 5 to get your child used to them.

To find your personal best peak flow number, take your peak flow each day for 2 to 3 weeks. Your asthma should be under control during this time. To find your personal best, take your peak flow as close to the following times of day as you can:

These times for taking your peak flow are only for finding your personal best.

Write down the number you get for each peak flow reading. The highest peak flow number you had during the 2 to 3 weeks is your personal best.

Ask your provider to help you fill out an asthma action plan. This plan should tell you when to call the provider for help and when to use medicines if your peak flow drops to a certain level.

Your personal best can change over time. Ask your provider when you should check for a new personal best.

Once you know your personal best, make taking your peak flow a habit. Take your peak flow:

Check to see which zone your peak flow number is in. Do what your provider told you to do when you are in that zone. This information should be in your action plan. If you use more than one peak flow meter (such as one at home and another one at school or work), be sure that all of them are the same brand.

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Review Date: 2/3/2024
Reviewed By: Frank D. Brodkey, MD, FCCM, Associate Professor, Section of Pulmonary and Critical Care Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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